Daniel Erat | 748945e | 2015-08-11 09:22:30 -0600 | [diff] [blame] | 1 | This is libmicrohttpd-tutorial.info, produced by makeinfo version 4.13 |
| 2 | from libmicrohttpd-tutorial.texi. |
| 3 | |
| 4 | INFO-DIR-SECTION Software libraries |
| 5 | START-INFO-DIR-ENTRY |
| 6 | * libmicrohttpdtutorial: (libmicrohttpd). A tutorial for GNU libmicrohttpd. |
| 7 | END-INFO-DIR-ENTRY |
| 8 | |
| 9 | This tutorial documents GNU libmicrohttpd version 0.9.23, last |
| 10 | updated 17 November 2013. |
| 11 | |
| 12 | Copyright (c) 2008 Sebastian Gerhardt. |
| 13 | |
| 14 | Copyright (c) 2010, 2011, 2012, 2013 Christian Grothoff. |
| 15 | |
| 16 | Permission is granted to copy, distribute and/or modify this |
| 17 | document under the terms of the GNU Free Documentation License, |
| 18 | Version 1.3 or any later version published by the Free Software |
| 19 | Foundation; with no Invariant Sections, no Front-Cover Texts, and |
| 20 | no Back-Cover Texts. A copy of the license is included in the |
| 21 | section entitled "GNU Free Documentation License". |
| 22 | |
| 23 | |
| 24 | File: libmicrohttpd-tutorial.info, Node: Top, Next: Introduction, Up: (dir) |
| 25 | |
| 26 | A Tutorial for GNU libmicrohttpd |
| 27 | ******************************** |
| 28 | |
| 29 | This tutorial documents GNU libmicrohttpd version 0.9.23, last updated |
| 30 | 17 November 2013. |
| 31 | |
| 32 | Copyright (c) 2008 Sebastian Gerhardt. |
| 33 | |
| 34 | Copyright (c) 2010, 2011, 2012, 2013 Christian Grothoff. |
| 35 | |
| 36 | Permission is granted to copy, distribute and/or modify this |
| 37 | document under the terms of the GNU Free Documentation License, |
| 38 | Version 1.3 or any later version published by the Free Software |
| 39 | Foundation; with no Invariant Sections, no Front-Cover Texts, and |
| 40 | no Back-Cover Texts. A copy of the license is included in the |
| 41 | section entitled "GNU Free Documentation License". |
| 42 | |
| 43 | * Menu: |
| 44 | |
| 45 | * Introduction:: |
| 46 | * Hello browser example:: |
| 47 | * Exploring requests:: |
| 48 | * Response headers:: |
| 49 | * Supporting basic authentication:: |
| 50 | * Processing POST data:: |
| 51 | * Improved processing of POST data:: |
| 52 | * Session management:: |
| 53 | * Adding a layer of security:: |
| 54 | * Bibliography:: |
| 55 | * License text:: |
| 56 | * Example programs:: |
| 57 | |
| 58 | |
| 59 | File: libmicrohttpd-tutorial.info, Node: Introduction, Next: Hello browser example, Prev: Top, Up: Top |
| 60 | |
| 61 | 1 Introduction |
| 62 | ************** |
| 63 | |
| 64 | This tutorial is for developers who want to learn how they can add HTTP |
| 65 | serving capabilities to their applications with the _GNU libmicrohttpd_ |
| 66 | library, abbreviated _MHD_. The reader will learn how to implement |
| 67 | basic HTTP functions from simple executable sample programs that |
| 68 | implement various features. |
| 69 | |
| 70 | The text is supposed to be a supplement to the API reference manual |
| 71 | of _GNU libmicrohttpd_ and for that reason does not explain many of the |
| 72 | parameters. Therefore, the reader should always consult the manual to |
| 73 | find the exact meaning of the functions used in the tutorial. |
| 74 | Furthermore, the reader is encouraged to study the relevant _RFCs_, |
| 75 | which document the HTTP standard. |
| 76 | |
| 77 | _GNU libmicrohttpd_ is assumed to be already installed. This |
| 78 | tutorial is written for version 0.9.23. At the time being, this |
| 79 | tutorial has only been tested on _GNU/Linux_ machines even though |
| 80 | efforts were made not to rely on anything that would prevent the |
| 81 | samples from being built on similar systems. |
| 82 | |
| 83 | 1.1 History |
| 84 | =========== |
| 85 | |
| 86 | This tutorial was originally written by Sebastian Gerhardt for MHD |
| 87 | 0.4.0. It was slighly polished and updated to MHD 0.9.0 by Christian |
| 88 | Grothoff. |
| 89 | |
| 90 | |
| 91 | File: libmicrohttpd-tutorial.info, Node: Hello browser example, Next: Exploring requests, Prev: Introduction, Up: Top |
| 92 | |
| 93 | 2 Hello browser example |
| 94 | *********************** |
| 95 | |
| 96 | The most basic task for a HTTP server is to deliver a static text |
| 97 | message to any client connecting to it. Given that this is also easy |
| 98 | to implement, it is an excellent problem to start with. |
| 99 | |
| 100 | For now, the particular URI the client asks for shall have no effect |
| 101 | on the message that will be returned. In addition, the server shall end |
| 102 | the connection after the message has been sent so that the client will |
| 103 | know there is nothing more to expect. |
| 104 | |
| 105 | The C program `hellobrowser.c', which is to be found in the examples |
| 106 | section, does just that. If you are very eager, you can compile and |
| 107 | start it right away but it is advisable to type the lines in by |
| 108 | yourself as they will be discussed and explained in detail. |
| 109 | |
| 110 | After the necessary includes and the definition of the port which |
| 111 | our server should listen on |
| 112 | #include <sys/types.h> |
| 113 | #include <sys/select.h> |
| 114 | #include <sys/socket.h> |
| 115 | #include <microhttpd.h> |
| 116 | |
| 117 | #define PORT 8888 |
| 118 | |
| 119 | the desired behaviour of our server when HTTP request arrive has to be |
| 120 | implemented. We already have agreed that it should not care about the |
| 121 | particular details of the request, such as who is requesting what. The |
| 122 | server will respond merely with the same small HTML page to every |
| 123 | request. |
| 124 | |
| 125 | The function we are going to write now will be called by _GNU |
| 126 | libmicrohttpd_ every time an appropriate request comes in. While the |
| 127 | name of this callback function is arbitrary, its parameter list has to |
| 128 | follow a certain layout. So please, ignore the lot of parameters for |
| 129 | now, they will be explained at the point they are needed. We have to |
| 130 | use only one of them, `struct MHD_Connection *connection', for the |
| 131 | minimalistic functionality we want to archive at the moment. |
| 132 | |
| 133 | This parameter is set by the _libmicrohttpd_ daemon and holds the |
| 134 | necessary information to relate the call with a certain connection. |
| 135 | Keep in mind that a server might have to satisfy hundreds of concurrent |
| 136 | connections and we have to make sure that the correct data is sent to |
| 137 | the destined client. Therefore, this variable is a means to refer to a |
| 138 | particular connection if we ask the daemon to sent the reply. |
| 139 | |
| 140 | Talking about the reply, it is defined as a string right after the |
| 141 | function header |
| 142 | int answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 143 | const char *url, |
| 144 | const char *method, const char *version, |
| 145 | const char *upload_data, |
| 146 | size_t *upload_data_size, void **con_cls) |
| 147 | { |
| 148 | const char *page = "<html><body>Hello, browser!</body></html>"; |
| 149 | |
| 150 | HTTP is a rather strict protocol and the client would certainly |
| 151 | consider it "inappropriate" if we just sent the answer string "as is". |
| 152 | Instead, it has to be wrapped with additional information stored in |
| 153 | so-called headers and footers. Most of the work in this area is done |
| 154 | by the library for us--we just have to ask. Our reply string packed in |
| 155 | the necessary layers will be called a "response". To obtain such a |
| 156 | response we hand our data (the reply-string) and its size over to the |
| 157 | `MHD_create_response_from_buffer' function. The last two parameters |
| 158 | basically tell _MHD_ that we do not want it to dispose the message data |
| 159 | for us when it has been sent and there also needs no internal copy to |
| 160 | be done because the _constant_ string won't change anyway. |
| 161 | |
| 162 | struct MHD_Response *response; |
| 163 | int ret; |
| 164 | |
| 165 | response = MHD_create_response_from_buffer (strlen (page), |
| 166 | (void*) page, MHD_RESPMEM_PERSISTENT); |
| 167 | |
| 168 | Now that the the response has been laced up, it is ready for delivery |
| 169 | and can be queued for sending. This is done by passing it to another |
| 170 | _GNU libmicrohttpd_ function. As all our work was done in the scope of |
| 171 | one function, the recipient is without doubt the one associated with the |
| 172 | local variable `connection' and consequently this variable is given to |
| 173 | the queue function. Every HTTP response is accompanied by a status |
| 174 | code, here "OK", so that the client knows this response is the intended |
| 175 | result of his request and not due to some error or malfunction. |
| 176 | |
| 177 | Finally, the packet is destroyed and the return value from the queue |
| 178 | returned, already being set at this point to either MHD_YES or MHD_NO |
| 179 | in case of success or failure. |
| 180 | |
| 181 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 182 | MHD_destroy_response (response); |
| 183 | |
| 184 | return ret; |
| 185 | } |
| 186 | |
| 187 | With the primary task of our server implemented, we can start the |
| 188 | actual server daemon which will listen on `PORT' for connections. This |
| 189 | is done in the main function. |
| 190 | int main () |
| 191 | { |
| 192 | struct MHD_Daemon *daemon; |
| 193 | |
| 194 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 195 | &answer_to_connection, NULL, MHD_OPTION_END); |
| 196 | if (NULL == daemon) return 1; |
| 197 | |
| 198 | The first parameter is one of three possible modes of operation. Here |
| 199 | we want the daemon to run in a separate thread and to manage all |
| 200 | incoming connections in the same thread. This means that while |
| 201 | producing the response for one connection, the other connections will |
| 202 | be put on hold. In this example, where the reply is already known and |
| 203 | therefore the request is served quickly, this poses no problem. |
| 204 | |
| 205 | We will allow all clients to connect regardless of their name or |
| 206 | location, therefore we do not check them on connection and set the |
| 207 | forth and fifth parameter to NULL. |
| 208 | |
| 209 | Parameter six is the address of the function we want to be called |
| 210 | whenever a new connection has been established. Our |
| 211 | `answer_to_connection' knows best what the client wants and needs no |
| 212 | additional information (which could be passed via the next parameter) |
| 213 | so the next parameter is NULL. Likewise, we do not need to pass extra |
| 214 | options to the daemon so we just write the MHD_OPTION_END as the last |
| 215 | parameter. |
| 216 | |
| 217 | As the server daemon runs in the background in its own thread, the |
| 218 | execution flow in our main function will contine right after the call. |
| 219 | Because of this, we must delay the execution flow in the main thread or |
| 220 | else the program will terminate prematurely. We let it pause in a |
| 221 | processing-time friendly manner by waiting for the enter key to be |
| 222 | pressed. In the end, we stop the daemon so it can do its cleanup tasks. |
| 223 | getchar (); |
| 224 | |
| 225 | MHD_stop_daemon (daemon); |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | The first example is now complete. |
| 230 | |
| 231 | Compile it with |
| 232 | cc hellobrowser.c -o hellobrowser -I$PATH_TO_LIBMHD_INCLUDES |
| 233 | -L$PATH_TO_LIBMHD_LIBS -lmicrohttpd |
| 234 | with the two paths set accordingly and run it. |
| 235 | |
| 236 | Now open your favorite Internet browser and go to the address |
| 237 | `http://localhost:8888/', provided that 8888 is the port you chose. If |
| 238 | everything works as expected, the browser will present the message of |
| 239 | the static HTML page it got from our minimal server. |
| 240 | |
| 241 | Remarks |
| 242 | ======= |
| 243 | |
| 244 | To keep this first example as small as possible, some drastic shortcuts |
| 245 | were taken and are to be discussed now. |
| 246 | |
| 247 | Firstly, there is no distinction made between the kinds of requests |
| 248 | a client could send. We implied that the client sends a GET request, |
| 249 | that means, that he actually asked for some data. Even when it is not |
| 250 | intended to accept POST requests, a good server should at least |
| 251 | recognize that this request does not constitute a legal request and |
| 252 | answer with an error code. This can be easily implemented by checking |
| 253 | if the parameter `method' equals the string "GET" and returning a |
| 254 | `MHD_NO' if not so. |
| 255 | |
| 256 | Secondly, the above practice of queuing a response upon the first |
| 257 | call of the callback function brings with it some limitations. This is |
| 258 | because the content of the message body will not be received if a |
| 259 | response is queued in the first iteration. Furthermore, the connection |
| 260 | will be closed right after the response has been transferred then. |
| 261 | This is typically not what you want as it disables HTTP pipelining. |
| 262 | The correct approach is to simply not queue a message on the first |
| 263 | callback unless there is an error. The `void**' argument to the |
| 264 | callback provides a location for storing information about the history |
| 265 | of the connection; for the first call, the pointer will point to NULL. |
| 266 | A simplistic way to differenciate the first call from others is to check |
| 267 | if the pointer is NULL and set it to a non-NULL value during the first |
| 268 | call. |
| 269 | |
| 270 | Both of these issues you will find addressed in the official |
| 271 | `minimal_example.c' residing in the `src/examples' directory of the |
| 272 | _MHD_ package. The source code of this program should look very |
| 273 | familiar to you by now and easy to understand. |
| 274 | |
| 275 | For our example, the `must_copy' and `must_free' parameter at the |
| 276 | response construction function could be set to `MHD_NO'. In the usual |
| 277 | case, responses cannot be sent immediately after being queued. For |
| 278 | example, there might be other data on the system that needs to be sent |
| 279 | with a higher priority. Nevertheless, the queue function will return |
| 280 | successfully--raising the problem that the data we have pointed to may |
| 281 | be invalid by the time it is about being sent. This is not an issue |
| 282 | here because we can expect the `page' string, which is a constant |
| 283 | _string literal_ here, to be static. That means it will be present and |
| 284 | unchanged for as long as the program runs. For dynamic data, one could |
| 285 | choose to either have _MHD_ free the memory `page' points to itself |
| 286 | when it is not longer needed or, alternatively, have the library to |
| 287 | make and manage its own copy of it. |
| 288 | |
| 289 | Exercises |
| 290 | ========= |
| 291 | |
| 292 | * While the server is running, use a program like `telnet' or |
| 293 | `netcat' to connect to it. Try to form a valid HTTP 1.1 request |
| 294 | yourself like GET /dontcare HTTP/1.1 |
| 295 | Host: itsme |
| 296 | <enter> |
| 297 | and see what the server returns to you. |
| 298 | |
| 299 | * Also, try other requests, like POST, and see how our server does |
| 300 | not mind and why. How far in malforming a request can you go |
| 301 | before the builtin functionality of _MHD_ intervenes and an |
| 302 | altered response is sent? Make sure you read about the status |
| 303 | codes in the _RFC_. |
| 304 | |
| 305 | * Add the option `MHD_USE_PEDANTIC_CHECKS' to the start function of |
| 306 | the daemon in `main'. Mind the special format of the parameter |
| 307 | list here which is described in the manual. How indulgent is the |
| 308 | server now to your input? |
| 309 | |
| 310 | * Let the main function take a string as the first command line |
| 311 | argument and pass `argv[1]' to the `MHD_start_daemon' function as |
| 312 | the sixth parameter. The address of this string will be passed to |
| 313 | the callback function via the `cls' variable. Decorate the text |
| 314 | given at the command line when the server is started with proper |
| 315 | HTML tags and send it as the response instead of the former static |
| 316 | string. |
| 317 | |
| 318 | * _Demanding:_ Write a separate function returning a string |
| 319 | containing some useful information, for example, the time. Pass |
| 320 | the function's address as the sixth parameter and evaluate this |
| 321 | function on every request anew in `answer_to_connection'. Remember |
| 322 | to free the memory of the string every time after satisfying the |
| 323 | request. |
| 324 | |
| 325 | |
| 326 | |
| 327 | File: libmicrohttpd-tutorial.info, Node: Exploring requests, Next: Response headers, Prev: Hello browser example, Up: Top |
| 328 | |
| 329 | 3 Exploring requests |
| 330 | ******************** |
| 331 | |
| 332 | This chapter will deal with the information which the client sends to |
| 333 | the server at every request. We are going to examine the most useful |
| 334 | fields of such an request and print them out in a readable manner. This |
| 335 | could be useful for logging facilities. |
| 336 | |
| 337 | The starting point is the _hellobrowser_ program with the former |
| 338 | response removed. |
| 339 | |
| 340 | This time, we just want to collect information in the callback |
| 341 | function, thus we will just return MHD_NO after we have probed the |
| 342 | request. This way, the connection is closed without much ado by the |
| 343 | server. |
| 344 | |
| 345 | static int |
| 346 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 347 | const char *url, |
| 348 | const char *method, const char *version, |
| 349 | const char *upload_data, |
| 350 | size_t *upload_data_size, void **con_cls) |
| 351 | { |
| 352 | ... |
| 353 | return MHD_NO; |
| 354 | } |
| 355 | The ellipsis marks the position where the following instructions shall |
| 356 | be inserted. |
| 357 | |
| 358 | We begin with the most obvious information available to the server, |
| 359 | the request line. You should already have noted that a request consists |
| 360 | of a command (or "HTTP method") and a URI (e.g. a filename). It also |
| 361 | contains a string for the version of the protocol which can be found in |
| 362 | `version'. To call it a "new request" is justified because we return |
| 363 | only `MHD_NO', thus ensuring the function will not be called again for |
| 364 | this connection. |
| 365 | printf ("New %s request for %s using version %s\n", method, url, version); |
| 366 | The rest of the information is a bit more hidden. Nevertheless, there |
| 367 | is lot of it sent from common Internet browsers. It is stored in |
| 368 | "key-value" pairs and we want to list what we find in the header. As |
| 369 | there is no mandatory set of keys a client has to send, each key-value |
| 370 | pair is printed out one by one until there are no more left. We do this |
| 371 | by writing a separate function which will be called for each pair just |
| 372 | like the above function is called for each HTTP request. It can then |
| 373 | print out the content of this pair. |
| 374 | int print_out_key (void *cls, enum MHD_ValueKind kind, |
| 375 | const char *key, const char *value) |
| 376 | { |
| 377 | printf ("%s: %s\n", key, value); |
| 378 | return MHD_YES; |
| 379 | } |
| 380 | To start the iteration process that calls our new function for every |
| 381 | key, the line |
| 382 | MHD_get_connection_values (connection, MHD_HEADER_KIND, &print_out_key, NULL); |
| 383 | needs to be inserted in the connection callback function too. The |
| 384 | second parameter tells the function that we are only interested in keys |
| 385 | from the general HTTP header of the request. Our iterating function |
| 386 | `print_out_key' does not rely on any additional information to fulfill |
| 387 | its duties so the last parameter can be NULL. |
| 388 | |
| 389 | All in all, this constitutes the complete `logging.c' program for |
| 390 | this chapter which can be found in the `examples' section. |
| 391 | |
| 392 | Connecting with any modern Internet browser should yield a handful |
| 393 | of keys. You should try to interpret them with the aid of _RFC 2616_. |
| 394 | Especially worth mentioning is the "Host" key which is often used to |
| 395 | serve several different websites hosted under one single IP address but |
| 396 | reachable by different domain names (this is called virtual hosting). |
| 397 | |
| 398 | Conclusion |
| 399 | ========== |
| 400 | |
| 401 | The introduced capabilities to itemize the content of a simple GET |
| 402 | request--especially the URI--should already allow the server to satisfy |
| 403 | clients' requests for small specific resources (e.g. files) or even |
| 404 | induce alteration of server state. However, the latter is not |
| 405 | recommended as the GET method (including its header data) is by |
| 406 | convention considered a "safe" operation, which should not change the |
| 407 | server's state in a significant way. By convention, GET operations can |
| 408 | thus be performed by crawlers and other automatic software. Naturally |
| 409 | actions like searching for a passed string are fine. |
| 410 | |
| 411 | Of course, no transmission can occur while the return value is still |
| 412 | set to `MHD_NO' in the callback function. |
| 413 | |
| 414 | Exercises |
| 415 | ========= |
| 416 | |
| 417 | * By parsing the `url' string and delivering responses accordingly, |
| 418 | implement a small server for "virtual" files. When asked for |
| 419 | `/index.htm{l}', let the response consist of a HTML page |
| 420 | containing a link to `/another.html' page which is also to be |
| 421 | created "on the fly" in case of being requested. If neither of |
| 422 | these two pages are requested, `MHD_HTTP_NOT_FOUND' shall be |
| 423 | returned accompanied by an informative message. |
| 424 | |
| 425 | * A very interesting information has still been ignored by our |
| 426 | logger--the client's IP address. Implement a callback function static int on_client_connect (void *cls, |
| 427 | const struct sockaddr *addr, |
| 428 | socklen_t addrlen) |
| 429 | that prints out the IP address in an appropriate format. You |
| 430 | might want to use the POSIX function `inet_ntoa' but bear in mind |
| 431 | that `addr' is actually just a structure containing other |
| 432 | substructures and is _not_ the variable this function expects. |
| 433 | Make sure to return `MHD_YES' so that the library knows the client |
| 434 | is allowed to connect (and to then process the request). If one |
| 435 | wanted to limit access basing on IP addresses, this would be the |
| 436 | place to do it. The address of your `on_client_connect' function |
| 437 | must be passed as the third parameter to the `MHD_start_daemon' |
| 438 | call. |
| 439 | |
| 440 | |
| 441 | |
| 442 | File: libmicrohttpd-tutorial.info, Node: Response headers, Next: Supporting basic authentication, Prev: Exploring requests, Up: Top |
| 443 | |
| 444 | 4 Response headers |
| 445 | ****************** |
| 446 | |
| 447 | Now that we are able to inspect the incoming request in great detail, |
| 448 | this chapter discusses the means to enrich the outgoing responses |
| 449 | likewise. |
| 450 | |
| 451 | As you have learned in the _Hello, Browser_ chapter, some obligatory |
| 452 | header fields are added and set automatically for simple responses by |
| 453 | the library itself but if more advanced features are desired, |
| 454 | additional fields have to be created. One of the possible fields is |
| 455 | the content type field and an example will be developed around it. |
| 456 | This will lead to an application capable of correctly serving different |
| 457 | types of files. |
| 458 | |
| 459 | When we responded with HTML page packed in the static string |
| 460 | previously, the client had no choice but guessing about how to handle |
| 461 | the response, because the server had not told him. What if we had sent |
| 462 | a picture or a sound file? Would the message have been understood or |
| 463 | merely been displayed as an endless stream of random characters in the |
| 464 | browser? This is what the mime content types are for. The header of |
| 465 | the response is extended by certain information about how the data is |
| 466 | to be interpreted. |
| 467 | |
| 468 | To introduce the concept, a picture of the format _PNG_ will be sent |
| 469 | to the client and labeled accordingly with `image/png'. Once again, we |
| 470 | can base the new example on the `hellobrowser' program. |
| 471 | |
| 472 | #define FILENAME "picture.png" |
| 473 | #define MIMETYPE "image/png" |
| 474 | |
| 475 | static int |
| 476 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 477 | const char *url, |
| 478 | const char *method, const char *version, |
| 479 | const char *upload_data, |
| 480 | size_t *upload_data_size, void **con_cls) |
| 481 | { |
| 482 | unsigned char *buffer = NULL; |
| 483 | struct MHD_Response *response; |
| 484 | We want the program to open the file for reading and determine its |
| 485 | size: |
| 486 | int fd; |
| 487 | int ret; |
| 488 | struct stat sbuf; |
| 489 | |
| 490 | if (0 != strcmp (method, "GET")) |
| 491 | return MHD_NO; |
| 492 | if ( (-1 == (fd = open (FILENAME, O_RDONLY))) || |
| 493 | (0 != fstat (fd, &sbuf)) ) |
| 494 | { |
| 495 | /* error accessing file */ |
| 496 | /* ... (see below) */ |
| 497 | } |
| 498 | /* ... (see below) */ |
| 499 | When dealing with files, there is a lot that could go wrong on the |
| 500 | server side and if so, the client should be informed with |
| 501 | `MHD_HTTP_INTERNAL_SERVER_ERROR'. |
| 502 | |
| 503 | /* error accessing file */ |
| 504 | if (fd != -1) close (fd); |
| 505 | const char *errorstr = |
| 506 | "<html><body>An internal server error has occured!\ |
| 507 | </body></html>"; |
| 508 | response = |
| 509 | MHD_create_response_from_buffer (strlen (errorstr), |
| 510 | (void *) errorstr, |
| 511 | MHD_RESPMEM_PERSISTENT); |
| 512 | if (response) |
| 513 | { |
| 514 | ret = |
| 515 | MHD_queue_response (connection, MHD_HTTP_INTERNAL_SERVER_ERROR, |
| 516 | response); |
| 517 | MHD_destroy_response (response); |
| 518 | |
| 519 | return MHD_YES; |
| 520 | } |
| 521 | else |
| 522 | return MHD_NO; |
| 523 | if (!ret) |
| 524 | { |
| 525 | const char *errorstr = "<html><body>An internal server error has occured!\ |
| 526 | </body></html>"; |
| 527 | |
| 528 | if (buffer) free(buffer); |
| 529 | |
| 530 | response = MHD_create_response_from_buffer (strlen(errorstr), (void*) errorstr, |
| 531 | MHD_RESPMEM_PERSISTENT); |
| 532 | |
| 533 | if (response) |
| 534 | { |
| 535 | ret = MHD_queue_response (connection, |
| 536 | MHD_HTTP_INTERNAL_SERVER_ERROR, |
| 537 | response); |
| 538 | MHD_destroy_response (response); |
| 539 | |
| 540 | return MHD_YES; |
| 541 | } |
| 542 | else return MHD_NO; |
| 543 | } |
| 544 | Note that we nevertheless have to create a response object even for |
| 545 | sending a simple error code. Otherwise, the connection would just be |
| 546 | closed without comment, leaving the client curious about what has |
| 547 | happened. |
| 548 | |
| 549 | But in the case of success a response will be constructed directly |
| 550 | from the file descriptor: |
| 551 | |
| 552 | /* error accessing file */ |
| 553 | /* ... (see above) */ |
| 554 | } |
| 555 | |
| 556 | response = |
| 557 | MHD_create_response_from_fd_at_offset (sbuf.st_size, fd, 0); |
| 558 | MHD_add_response_header (response, "Content-Type", MIMETYPE); |
| 559 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 560 | MHD_destroy_response (response); |
| 561 | Note that the response object will take care of closing the file |
| 562 | desciptor for us. |
| 563 | |
| 564 | Up to this point, there was little new. The actual novelty is that |
| 565 | we enhance the header with the meta data about the content. Aware of |
| 566 | the field's name we want to add, it is as easy as that: |
| 567 | MHD_add_response_header(response, "Content-Type", MIMETYPE); |
| 568 | We do not have to append a colon expected by the protocol behind the |
| 569 | first field--_GNU libhttpdmicro_ will take care of this. |
| 570 | |
| 571 | The function finishes with the well-known lines |
| 572 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 573 | MHD_destroy_response (response); |
| 574 | return ret; |
| 575 | } |
| 576 | The complete program `responseheaders.c' is in the `examples' section |
| 577 | as usual. Find a _PNG_ file you like and save it to the directory the |
| 578 | example is run from under the name `picture.png'. You should find the |
| 579 | image displayed on your browser if everything worked well. |
| 580 | |
| 581 | Remarks |
| 582 | ======= |
| 583 | |
| 584 | The include file of the _MHD_ library comes with the header types |
| 585 | mentioned in _RFC 2616_ already defined as macros. Thus, we could have |
| 586 | written `MHD_HTTP_HEADER_CONTENT_TYPE' instead of `"Content-Type"' as |
| 587 | well. However, one is not limited to these standard headers and could |
| 588 | add custom response headers without violating the protocol. Whether, |
| 589 | and how, the client would react to these custom header is up to the |
| 590 | receiver. Likewise, the client is allowed to send custom request |
| 591 | headers to the server as well, opening up yet more possibilities how |
| 592 | client and server could communicate with each other. |
| 593 | |
| 594 | The method of creating the response from a file on disk only works |
| 595 | for static content. Serving dynamically created responses will be a |
| 596 | topic of a future chapter. |
| 597 | |
| 598 | Exercises |
| 599 | ========= |
| 600 | |
| 601 | * Remember that the original program was written under a few |
| 602 | assumptions--a static response using a local file being one of |
| 603 | them. In order to simulate a very large or hard to reach file that |
| 604 | cannot be provided instantly, postpone the queuing in the callback |
| 605 | with the `sleep' function for 30 seconds _if_ the file `/big.png' |
| 606 | is requested (but deliver the same as above). A request for |
| 607 | `/picture.png' should provide just the same but without any |
| 608 | artificial delays. |
| 609 | |
| 610 | Now start two instances of your browser (or even use two machines) |
| 611 | and see how the second client is put on hold while the first waits |
| 612 | for his request on the slow file to be fulfilled. |
| 613 | |
| 614 | Finally, change the sourcecode to use |
| 615 | `MHD_USE_THREAD_PER_CONNECTION' when the daemon is started and try |
| 616 | again. |
| 617 | |
| 618 | * Did you succeed in implementing the clock exercise yet? This time, |
| 619 | let the server save the program's start time `t' and implement a |
| 620 | response simulating a countdown that reaches 0 at `t+60'. |
| 621 | Returning a message saying on which point the countdown is, the |
| 622 | response should ultimately be to reply "Done" if the program has |
| 623 | been running long enough, |
| 624 | |
| 625 | An unofficial, but widely understood, response header line is |
| 626 | `Refresh: DELAY; url=URL' with the uppercase words substituted to |
| 627 | tell the client it should request the given resource after the |
| 628 | given delay again. Improve your program in that the browser (any |
| 629 | modern browser should work) automatically reconnects and asks for |
| 630 | the status again every 5 seconds or so. The URL would have to be |
| 631 | composed so that it begins with "http://", followed by the _URI_ |
| 632 | the server is reachable from the client's point of view. |
| 633 | |
| 634 | Maybe you want also to visualize the countdown as a status bar by |
| 635 | creating a `<table>' consisting of one row and `n' columns whose |
| 636 | fields contain small images of either a red or a green light. |
| 637 | |
| 638 | |
| 639 | |
| 640 | File: libmicrohttpd-tutorial.info, Node: Supporting basic authentication, Next: Processing POST data, Prev: Response headers, Up: Top |
| 641 | |
| 642 | 5 Supporting basic authentication |
| 643 | ********************************* |
| 644 | |
| 645 | With the small exception of IP address based access control, requests |
| 646 | from all connecting clients where served equally until now. This |
| 647 | chapter discusses a first method of client's authentication and its |
| 648 | limits. |
| 649 | |
| 650 | A very simple approach feasible with the means already discussed |
| 651 | would be to expect the password in the _URI_ string before granting |
| 652 | access to the secured areas. The password could be separated from the |
| 653 | actual resource identifier by a certain character, thus the request |
| 654 | line might look like |
| 655 | GET /picture.png?mypassword |
| 656 | In the rare situation where the client is customized enough and the |
| 657 | connection occurs through secured lines (e.g., a embedded device |
| 658 | directly attached to another via wire) and where the ability to embedd |
| 659 | a password in the URI or to pass on a URI with a password are desired, |
| 660 | this can be a reasonable choice. |
| 661 | |
| 662 | But when it is assumed that the user connecting does so with an |
| 663 | ordinary Internet browser, this implementation brings some problems |
| 664 | about. For example, the URI including the password stays in the address |
| 665 | field or at least in the history of the browser for anybody near enough |
| 666 | to see. It will also be inconvenient to add the password manually to |
| 667 | any new URI when the browser does not know how to compose this |
| 668 | automatically. |
| 669 | |
| 670 | At least the convenience issue can be addressed by employing the |
| 671 | simplest built-in password facilities of HTTP compliant browsers, hence |
| 672 | we want to start there. It will however turn out to have still severe |
| 673 | weaknesses in terms of security which need consideration. |
| 674 | |
| 675 | Before we will start implementing _Basic Authentication_ as |
| 676 | described in _RFC 2617_, we should finally abandon the bad practice of |
| 677 | responding every request the first time our callback is called for a |
| 678 | given connection. This is becoming more important now because the |
| 679 | client and the server will have to talk in a more bi-directional way |
| 680 | than before to |
| 681 | |
| 682 | But how can we tell whether the callback has been called before for |
| 683 | the particular connection? Initially, the pointer this parameter |
| 684 | references is set by _MHD_ in the callback. But it will also be |
| 685 | "remembered" on the next call (for the same connection). Thus, we will |
| 686 | generate no response until the parameter is non-null--implying the |
| 687 | callback was called before at least once. We do not need to share |
| 688 | information between different calls of the callback, so we can set the |
| 689 | parameter to any adress that is assured to be not null. The pointer to |
| 690 | the `connection' structure will be pointing to a legal address, so we |
| 691 | take this. |
| 692 | |
| 693 | The first time `answer_to_connection' is called, we will not even |
| 694 | look at the headers. |
| 695 | |
| 696 | static int |
| 697 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 698 | const char *url, const char *method, const char *version, |
| 699 | const char *upload_data, size_t *upload_data_size, |
| 700 | void **con_cls) |
| 701 | { |
| 702 | if (0 != strcmp(method, "GET")) return MHD_NO; |
| 703 | if (NULL == *con_cls) {*con_cls = connection; return MHD_YES;} |
| 704 | |
| 705 | ... |
| 706 | /* else respond accordingly */ |
| 707 | ... |
| 708 | } |
| 709 | Note how we lop off the connection on the first condition (no "GET" |
| 710 | request), but return asking for more on the other one with `MHD_YES'. |
| 711 | With this minor change, we can proceed to implement the actual |
| 712 | authentication process. |
| 713 | |
| 714 | Request for authentication |
| 715 | ========================== |
| 716 | |
| 717 | Let us assume we had only files not intended to be handed out without |
| 718 | the correct username/password, so every "GET" request will be |
| 719 | challenged. _RFC 2617_ describes how the server shall ask for |
| 720 | authentication by adding a _WWW-Authenticate_ response header with the |
| 721 | name of the _realm_ protected. MHD can generate and queue such a |
| 722 | failure response for you using the `MHD_queue_basic_auth_fail_response' |
| 723 | API. The only thing you need to do is construct a response with the |
| 724 | error page to be shown to the user if he aborts basic authentication. |
| 725 | But first, you should check if the proper credentials were already |
| 726 | supplied using the `MHD_basic_auth_get_username_password' call. |
| 727 | |
| 728 | Your code would then look like this: |
| 729 | static int |
| 730 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 731 | const char *url, const char *method, |
| 732 | const char *version, const char *upload_data, |
| 733 | size_t *upload_data_size, void **con_cls) |
| 734 | { |
| 735 | char *user; |
| 736 | char *pass; |
| 737 | int fail; |
| 738 | struct MHD_Response *response; |
| 739 | |
| 740 | if (0 != strcmp (method, MHD_HTTP_METHOD_GET)) |
| 741 | return MHD_NO; |
| 742 | if (NULL == *con_cls) |
| 743 | { |
| 744 | *con_cls = connection; |
| 745 | return MHD_YES; |
| 746 | } |
| 747 | pass = NULL; |
| 748 | user = MHD_basic_auth_get_username_password (connection, &pass); |
| 749 | fail = ( (user == NULL) || |
| 750 | (0 != strcmp (user, "root")) || |
| 751 | (0 != strcmp (pass, "pa$$w0rd") ) ); |
| 752 | if (user != NULL) free (user); |
| 753 | if (pass != NULL) free (pass); |
| 754 | if (fail) |
| 755 | { |
| 756 | const char *page = "<html><body>Go away.</body></html>"; |
| 757 | response = |
| 758 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 759 | MHD_RESPMEM_PERSISTENT); |
| 760 | ret = MHD_queue_basic_auth_fail_response (connection, |
| 761 | "my realm", |
| 762 | response); |
| 763 | } |
| 764 | else |
| 765 | { |
| 766 | const char *page = "<html><body>A secret.</body></html>"; |
| 767 | response = |
| 768 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 769 | MHD_RESPMEM_PERSISTENT); |
| 770 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 771 | } |
| 772 | MHD_destroy_response (response); |
| 773 | return ret; |
| 774 | } |
| 775 | |
| 776 | See the `examples' directory for the complete example file. |
| 777 | |
| 778 | Remarks |
| 779 | ======= |
| 780 | |
| 781 | For a proper server, the conditional statements leading to a return of |
| 782 | `MHD_NO' should yield a response with a more precise status code |
| 783 | instead of silently closing the connection. For example, failures of |
| 784 | memory allocation are best reported as _internal server error_ and |
| 785 | unexpected authentication methods as _400 bad request_. |
| 786 | |
| 787 | Exercises |
| 788 | ========= |
| 789 | |
| 790 | * Make the server respond to wrong credentials (but otherwise |
| 791 | well-formed requests) with the recommended _401 unauthorized_ |
| 792 | status code. If the client still does not authenticate correctly |
| 793 | within the same connection, close it and store the client's IP |
| 794 | address for a certain time. (It is OK to check for expiration not |
| 795 | until the main thread wakes up again on the next connection.) If |
| 796 | the client fails authenticating three times during this period, |
| 797 | add it to another list for which the `AcceptPolicyCallback' |
| 798 | function denies connection (temporally). |
| 799 | |
| 800 | * With the network utility `netcat' connect and log the response of |
| 801 | a "GET" request as you did in the exercise of the first example, |
| 802 | this time to a file. Now stop the server and let _netcat_ listen |
| 803 | on the same port the server used to listen on and have it fake |
| 804 | being the proper server by giving the file's content as the |
| 805 | response (e.g. `cat log | nc -l -p 8888'). Pretending to think |
| 806 | your were connecting to the actual server, browse to the |
| 807 | eavesdropper and give the correct credentials. |
| 808 | |
| 809 | Copy and paste the encoded string you see in `netcat''s output to |
| 810 | some of the Base64 decode tools available online and see how both |
| 811 | the user's name and password could be completely restored. |
| 812 | |
| 813 | |
| 814 | |
| 815 | File: libmicrohttpd-tutorial.info, Node: Processing POST data, Next: Improved processing of POST data, Prev: Supporting basic authentication, Up: Top |
| 816 | |
| 817 | 6 Processing POST data |
| 818 | ********************** |
| 819 | |
| 820 | The previous chapters already have demonstrated a variety of |
| 821 | possibilities to send information to the HTTP server, but it is not |
| 822 | recommended that the _GET_ method is used to alter the way the server |
| 823 | operates. To induce changes on the server, the _POST_ method is |
| 824 | preferred over and is much more powerful than _GET_ and will be |
| 825 | introduced in this chapter. |
| 826 | |
| 827 | We are going to write an application that asks for the visitor's |
| 828 | name and, after the user has posted it, composes an individual response |
| 829 | text. Even though it was not mandatory to use the _POST_ method here, |
| 830 | as there is no permanent change caused by the POST, it is an |
| 831 | illustrative example on how to share data between different functions |
| 832 | for the same connection. Furthermore, the reader should be able to |
| 833 | extend it easily. |
| 834 | |
| 835 | GET request |
| 836 | =========== |
| 837 | |
| 838 | When the first _GET_ request arrives, the server shall respond with a |
| 839 | HTML page containing an edit field for the name. |
| 840 | |
| 841 | const char* askpage = "<html><body>\ |
| 842 | What's your name, Sir?<br>\ |
| 843 | <form action=\"/namepost\" method=\"post\">\ |
| 844 | <input name=\"name\" type=\"text\"\ |
| 845 | <input type=\"submit\" value=\" Send \"></form>\ |
| 846 | </body></html>"; |
| 847 | The `action' entry is the _URI_ to be called by the browser when |
| 848 | posting, and the `name' will be used later to be sure it is the |
| 849 | editbox's content that has been posted. |
| 850 | |
| 851 | We also prepare the answer page, where the name is to be filled in |
| 852 | later, and an error page as the response for anything but proper _GET_ |
| 853 | and _POST_ requests: |
| 854 | |
| 855 | const char* greatingpage="<html><body><h1>Welcome, %s!</center></h1></body></html>"; |
| 856 | |
| 857 | const char* errorpage="<html><body>This doesn't seem to be right.</body></html>"; |
| 858 | Whenever we need to send a page, we use an extra function `int |
| 859 | send_page(struct MHD_Connection *connection, const char* page)' for |
| 860 | this, which does not contain anything new and whose implementation is |
| 861 | therefore not discussed further in the tutorial. |
| 862 | |
| 863 | POST request |
| 864 | ============ |
| 865 | |
| 866 | Posted data can be of arbitrary and considerable size; for example, if |
| 867 | a user uploads a big image to the server. Similar to the case of the |
| 868 | header fields, there may also be different streams of posted data, such |
| 869 | as one containing the text of an editbox and another the state of a |
| 870 | button. Likewise, we will have to register an iterator function that |
| 871 | is going to be called maybe several times not only if there are |
| 872 | different POSTs but also if one POST has only been received partly yet |
| 873 | and needs processing before another chunk can be received. |
| 874 | |
| 875 | Such an iterator function is called by a _postprocessor_, which must |
| 876 | be created upon arriving of the post request. We want the iterator |
| 877 | function to read the first post data which is tagged `name' and to |
| 878 | create an individual greeting string based on the template and the name. |
| 879 | But in order to pass this string to other functions and still be able |
| 880 | to differentiate different connections, we must first define a |
| 881 | structure to share the information, holding the most import entries. |
| 882 | |
| 883 | struct connection_info_struct |
| 884 | { |
| 885 | int connectiontype; |
| 886 | char *answerstring; |
| 887 | struct MHD_PostProcessor *postprocessor; |
| 888 | }; |
| 889 | With these information available to the iterator function, it is able |
| 890 | to fulfill its task. Once it has composed the greeting string, it |
| 891 | returns `MHD_NO' to inform the post processor that it does not need to |
| 892 | be called again. Note that this function does not handle processing of |
| 893 | data for the same `key'. If we were to expect that the name will be |
| 894 | posted in several chunks, we had to expand the namestring dynamically |
| 895 | as additional parts of it with the same `key' came in. But in this |
| 896 | example, the name is assumed to fit entirely inside one single packet. |
| 897 | |
| 898 | static int |
| 899 | iterate_post (void *coninfo_cls, enum MHD_ValueKind kind, const char *key, |
| 900 | const char *filename, const char *content_type, |
| 901 | const char *transfer_encoding, const char *data, |
| 902 | uint64_t off, size_t size) |
| 903 | { |
| 904 | struct connection_info_struct *con_info = coninfo_cls; |
| 905 | |
| 906 | if (0 == strcmp (key, "name")) |
| 907 | { |
| 908 | if ((size > 0) && (size <= MAXNAMESIZE)) |
| 909 | { |
| 910 | char *answerstring; |
| 911 | answerstring = malloc (MAXANSWERSIZE); |
| 912 | if (!answerstring) return MHD_NO; |
| 913 | |
| 914 | snprintf (answerstring, MAXANSWERSIZE, greatingpage, data); |
| 915 | con_info->answerstring = answerstring; |
| 916 | } |
| 917 | else con_info->answerstring = NULL; |
| 918 | |
| 919 | return MHD_NO; |
| 920 | } |
| 921 | |
| 922 | return MHD_YES; |
| 923 | } |
| 924 | Once a connection has been established, it can be terminated for many |
| 925 | reasons. As these reasons include unexpected events, we have to |
| 926 | register another function that cleans up any resources that might have |
| 927 | been allocated for that connection by us, namely the post processor and |
| 928 | the greetings string. This cleanup function must take into account that |
| 929 | it will also be called for finished requests other than _POST_ requests. |
| 930 | |
| 931 | void request_completed (void *cls, struct MHD_Connection *connection, |
| 932 | void **con_cls, |
| 933 | enum MHD_RequestTerminationCode toe) |
| 934 | { |
| 935 | struct connection_info_struct *con_info = *con_cls; |
| 936 | |
| 937 | if (NULL == con_info) return; |
| 938 | if (con_info->connectiontype == POST) |
| 939 | { |
| 940 | MHD_destroy_post_processor (con_info->postprocessor); |
| 941 | if (con_info->answerstring) free (con_info->answerstring); |
| 942 | } |
| 943 | |
| 944 | free (con_info); |
| 945 | *con_cls = NULL; |
| 946 | } |
| 947 | _GNU libmicrohttpd_ is informed that it shall call the above function |
| 948 | when the daemon is started in the main function. |
| 949 | |
| 950 | ... |
| 951 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 952 | &answer_to_connection, NULL, |
| 953 | MHD_OPTION_NOTIFY_COMPLETED, &request_completed, NULL, |
| 954 | MHD_OPTION_END); |
| 955 | ... |
| 956 | |
| 957 | Request handling |
| 958 | ================ |
| 959 | |
| 960 | With all other functions prepared, we can now discuss the actual |
| 961 | request handling. |
| 962 | |
| 963 | On the first iteration for a new request, we start by allocating a |
| 964 | new instance of a `struct connection_info_struct' structure, which will |
| 965 | store all necessary information for later iterations and other |
| 966 | functions. |
| 967 | |
| 968 | static int |
| 969 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 970 | const char *url, |
| 971 | const char *method, const char *version, |
| 972 | const char *upload_data, |
| 973 | size_t *upload_data_size, void **con_cls) |
| 974 | { |
| 975 | if(NULL == *con_cls) |
| 976 | { |
| 977 | struct connection_info_struct *con_info; |
| 978 | |
| 979 | con_info = malloc (sizeof (struct connection_info_struct)); |
| 980 | if (NULL == con_info) return MHD_NO; |
| 981 | con_info->answerstring = NULL; |
| 982 | If the new request is a _POST_, the postprocessor must be created now. |
| 983 | In addition, the type of the request is stored for convenience. |
| 984 | if (0 == strcmp (method, "POST")) |
| 985 | { |
| 986 | con_info->postprocessor |
| 987 | = MHD_create_post_processor (connection, POSTBUFFERSIZE, |
| 988 | iterate_post, (void*) con_info); |
| 989 | |
| 990 | if (NULL == con_info->postprocessor) |
| 991 | { |
| 992 | free (con_info); |
| 993 | return MHD_NO; |
| 994 | } |
| 995 | con_info->connectiontype = POST; |
| 996 | } |
| 997 | else con_info->connectiontype = GET; |
| 998 | The address of our structure will both serve as the indicator for |
| 999 | successive iterations and to remember the particular details about the |
| 1000 | connection. |
| 1001 | *con_cls = (void*) con_info; |
| 1002 | return MHD_YES; |
| 1003 | } |
| 1004 | The rest of the function will not be executed on the first iteration. |
| 1005 | A _GET_ request is easily satisfied by sending the question form. |
| 1006 | if (0 == strcmp (method, "GET")) |
| 1007 | { |
| 1008 | return send_page (connection, askpage); |
| 1009 | } |
| 1010 | In case of _POST_, we invoke the post processor for as long as data |
| 1011 | keeps incoming, setting `*upload_data_size' to zero in order to |
| 1012 | indicate that we have processed--or at least have considered--all of it. |
| 1013 | if (0 == strcmp (method, "POST")) |
| 1014 | { |
| 1015 | struct connection_info_struct *con_info = *con_cls; |
| 1016 | |
| 1017 | if (*upload_data_size != 0) |
| 1018 | { |
| 1019 | MHD_post_process (con_info->postprocessor, upload_data, |
| 1020 | *upload_data_size); |
| 1021 | *upload_data_size = 0; |
| 1022 | |
| 1023 | return MHD_YES; |
| 1024 | } |
| 1025 | else if (NULL != con_info->answerstring) |
| 1026 | return send_page (connection, con_info->answerstring); |
| 1027 | } |
| 1028 | Finally, if they are neither _GET_ nor _POST_ requests, the error page |
| 1029 | is returned. |
| 1030 | return send_page(connection, errorpage); |
| 1031 | } |
| 1032 | These were the important parts of the program `simplepost.c'. |
| 1033 | |
| 1034 | |
| 1035 | File: libmicrohttpd-tutorial.info, Node: Improved processing of POST data, Next: Session management, Prev: Processing POST data, Up: Top |
| 1036 | |
| 1037 | 7 Improved processing of POST data |
| 1038 | ********************************** |
| 1039 | |
| 1040 | The previous chapter introduced a way to upload data to the server, but |
| 1041 | the developed example program has some shortcomings, such as not being |
| 1042 | able to handle larger chunks of data. In this chapter, we are going to |
| 1043 | discuss a more advanced server program that allows clients to upload a |
| 1044 | file in order to have it stored on the server's filesystem. The server |
| 1045 | shall also watch and limit the number of clients concurrently |
| 1046 | uploading, responding with a proper busy message if necessary. |
| 1047 | |
| 1048 | Prepared answers |
| 1049 | ================ |
| 1050 | |
| 1051 | We choose to operate the server with the `SELECT_INTERNALLY' method. |
| 1052 | This makes it easier to synchronize the global states at the cost of |
| 1053 | possible delays for other connections if the processing of a request is |
| 1054 | too slow. One of these variables that needs to be shared for all |
| 1055 | connections is the total number of clients that are uploading. |
| 1056 | |
| 1057 | #define MAXCLIENTS 2 |
| 1058 | static unsigned int nr_of_uploading_clients = 0; |
| 1059 | If there are too many clients uploading, we want the server to respond |
| 1060 | to all requests with a busy message. |
| 1061 | const char* busypage = |
| 1062 | "<html><body>This server is busy, please try again later.</body></html>"; |
| 1063 | Otherwise, the server will send a _form_ that informs the user of the |
| 1064 | current number of uploading clients, and ask her to pick a file on her |
| 1065 | local filesystem which is to be uploaded. |
| 1066 | const char* askpage = "<html><body>\n\ |
| 1067 | Upload a file, please!<br>\n\ |
| 1068 | There are %u clients uploading at the moment.<br>\n\ |
| 1069 | <form action=\"/filepost\" method=\"post\" \ |
| 1070 | enctype=\"multipart/form-data\">\n\ |
| 1071 | <input name=\"file\" type=\"file\">\n\ |
| 1072 | <input type=\"submit\" value=\" Send \"></form>\n\ |
| 1073 | </body></html>"; |
| 1074 | If the upload has succeeded, the server will respond with a message |
| 1075 | saying so. |
| 1076 | const char* completepage = "<html><body>The upload has been completed.</body></html>"; |
| 1077 | We want the server to report internal errors, such as memory shortage |
| 1078 | or file access problems, adequately. |
| 1079 | const char* servererrorpage |
| 1080 | = "<html><body>An internal server error has occured.</body></html>"; |
| 1081 | const char* fileexistspage |
| 1082 | = "<html><body>This file already exists.</body></html>"; |
| 1083 | It would be tolerable to send all these responses undifferentiated |
| 1084 | with a `200 HTTP_OK' status code but in order to improve the `HTTP' |
| 1085 | conformance of our server a bit, we extend the `send_page' function so |
| 1086 | that it accepts individual status codes. |
| 1087 | |
| 1088 | static int |
| 1089 | send_page (struct MHD_Connection *connection, |
| 1090 | const char* page, int status_code) |
| 1091 | { |
| 1092 | int ret; |
| 1093 | struct MHD_Response *response; |
| 1094 | |
| 1095 | response = MHD_create_response_from_buffer (strlen (page), (void*) page, |
| 1096 | MHD_RESPMEM_MUST_COPY); |
| 1097 | if (!response) return MHD_NO; |
| 1098 | |
| 1099 | ret = MHD_queue_response (connection, status_code, response); |
| 1100 | MHD_destroy_response (response); |
| 1101 | |
| 1102 | return ret; |
| 1103 | } |
| 1104 | Note how we ask _MHD_ to make its own copy of the message data. The |
| 1105 | reason behind this will become clear later. |
| 1106 | |
| 1107 | Connection cycle |
| 1108 | ================ |
| 1109 | |
| 1110 | The decision whether the server is busy or not is made right at the |
| 1111 | beginning of the connection. To do that at this stage is especially |
| 1112 | important for _POST_ requests because if no response is queued at this |
| 1113 | point, and `MHD_YES' returned, _MHD_ will not sent any queued messages |
| 1114 | until a postprocessor has been created and the post iterator is called |
| 1115 | at least once. |
| 1116 | |
| 1117 | static int |
| 1118 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 1119 | const char *url, |
| 1120 | const char *method, const char *version, |
| 1121 | const char *upload_data, |
| 1122 | size_t *upload_data_size, void **con_cls) |
| 1123 | { |
| 1124 | if (NULL == *con_cls) |
| 1125 | { |
| 1126 | struct connection_info_struct *con_info; |
| 1127 | |
| 1128 | if (nr_of_uploading_clients >= MAXCLIENTS) |
| 1129 | return send_page(connection, busypage, MHD_HTTP_SERVICE_UNAVAILABLE); |
| 1130 | If the server is not busy, the `connection_info' structure is |
| 1131 | initialized as usual, with the addition of a filepointer for each |
| 1132 | connection. |
| 1133 | |
| 1134 | con_info = malloc (sizeof (struct connection_info_struct)); |
| 1135 | if (NULL == con_info) return MHD_NO; |
| 1136 | con_info->fp = 0; |
| 1137 | |
| 1138 | if (0 == strcmp (method, "POST")) |
| 1139 | { |
| 1140 | ... |
| 1141 | } |
| 1142 | else con_info->connectiontype = GET; |
| 1143 | |
| 1144 | *con_cls = (void*) con_info; |
| 1145 | |
| 1146 | return MHD_YES; |
| 1147 | } |
| 1148 | For _POST_ requests, the postprocessor is created and we register a |
| 1149 | new uploading client. From this point on, there are many possible |
| 1150 | places for errors to occur that make it necessary to interrupt the |
| 1151 | uploading process. We need a means of having the proper response |
| 1152 | message ready at all times. Therefore, the `connection_info' structure |
| 1153 | is extended to hold the most current response message so that whenever |
| 1154 | a response is sent, the client will get the most informative message. |
| 1155 | Here, the structure is initialized to "no error". |
| 1156 | if (0 == strcmp (method, "POST")) |
| 1157 | { |
| 1158 | con_info->postprocessor |
| 1159 | = MHD_create_post_processor (connection, POSTBUFFERSIZE, |
| 1160 | iterate_post, (void*) con_info); |
| 1161 | |
| 1162 | if (NULL == con_info->postprocessor) |
| 1163 | { |
| 1164 | free (con_info); |
| 1165 | return MHD_NO; |
| 1166 | } |
| 1167 | |
| 1168 | nr_of_uploading_clients++; |
| 1169 | |
| 1170 | con_info->connectiontype = POST; |
| 1171 | con_info->answercode = MHD_HTTP_OK; |
| 1172 | con_info->answerstring = completepage; |
| 1173 | } |
| 1174 | else con_info->connectiontype = GET; |
| 1175 | If the connection handler is called for the second time, _GET_ |
| 1176 | requests will be answered with the _form_. We can keep the buffer under |
| 1177 | function scope, because we asked _MHD_ to make its own copy of it for |
| 1178 | as long as it is needed. |
| 1179 | if (0 == strcmp (method, "GET")) |
| 1180 | { |
| 1181 | int ret; |
| 1182 | char buffer[1024]; |
| 1183 | |
| 1184 | sprintf (buffer, askpage, nr_of_uploading_clients); |
| 1185 | return send_page (connection, buffer, MHD_HTTP_OK); |
| 1186 | } |
| 1187 | The rest of the `answer_to_connection' function is very similar to the |
| 1188 | `simplepost.c' example, except the more flexible content of the |
| 1189 | responses. The _POST_ data is processed until there is none left and |
| 1190 | the execution falls through to return an error page if the connection |
| 1191 | constituted no expected request method. |
| 1192 | if (0 == strcmp (method, "POST")) |
| 1193 | { |
| 1194 | struct connection_info_struct *con_info = *con_cls; |
| 1195 | |
| 1196 | if (0 != *upload_data_size) |
| 1197 | { |
| 1198 | MHD_post_process (con_info->postprocessor, |
| 1199 | upload_data, *upload_data_size); |
| 1200 | *upload_data_size = 0; |
| 1201 | |
| 1202 | return MHD_YES; |
| 1203 | } |
| 1204 | else |
| 1205 | return send_page (connection, con_info->answerstring, |
| 1206 | con_info->answercode); |
| 1207 | } |
| 1208 | |
| 1209 | return send_page(connection, errorpage, MHD_HTTP_BAD_REQUEST); |
| 1210 | } |
| 1211 | |
| 1212 | Storing to data |
| 1213 | =============== |
| 1214 | |
| 1215 | Unlike the `simplepost.c' example, here it is to be expected that post |
| 1216 | iterator will be called several times now. This means that for any |
| 1217 | given connection (there might be several concurrent of them) the posted |
| 1218 | data has to be written to the correct file. That is why we store a file |
| 1219 | handle in every `connection_info', so that the it is preserved between |
| 1220 | successive iterations. |
| 1221 | static int |
| 1222 | iterate_post (void *coninfo_cls, enum MHD_ValueKind kind, |
| 1223 | const char *key, |
| 1224 | const char *filename, const char *content_type, |
| 1225 | const char *transfer_encoding, const char *data, |
| 1226 | uint64_t off, size_t size) |
| 1227 | { |
| 1228 | struct connection_info_struct *con_info = coninfo_cls; |
| 1229 | Because the following actions depend heavily on correct file |
| 1230 | processing, which might be error prone, we default to reporting |
| 1231 | internal errors in case anything will go wrong. |
| 1232 | |
| 1233 | con_info->answerstring = servererrorpage; |
| 1234 | con_info->answercode = MHD_HTTP_INTERNAL_SERVER_ERROR; |
| 1235 | In the "askpage" _form_, we told the client to label its post data |
| 1236 | with the "file" key. Anything else would be an error. |
| 1237 | |
| 1238 | if (0 != strcmp (key, "file")) return MHD_NO; |
| 1239 | If the iterator is called for the first time, no file will have been |
| 1240 | opened yet. The `filename' string contains the name of the file |
| 1241 | (without any paths) the user selected on his system. We want to take |
| 1242 | this as the name the file will be stored on the server and make sure no |
| 1243 | file of that name exists (or is being uploaded) before we create one |
| 1244 | (note that the code below technically contains a race between the two |
| 1245 | "fopen" calls, but we will overlook this for portability sake). |
| 1246 | if (!con_info->fp) |
| 1247 | { |
| 1248 | if (NULL != (fp = fopen (filename, "rb")) ) |
| 1249 | { |
| 1250 | fclose (fp); |
| 1251 | con_info->answerstring = fileexistspage; |
| 1252 | con_info->answercode = MHD_HTTP_FORBIDDEN; |
| 1253 | return MHD_NO; |
| 1254 | } |
| 1255 | |
| 1256 | con_info->fp = fopen (filename, "ab"); |
| 1257 | if (!con_info->fp) return MHD_NO; |
| 1258 | } |
| 1259 | Occasionally, the iterator function will be called even when there are |
| 1260 | 0 new bytes to process. The server only needs to write data to the file |
| 1261 | if there is some. |
| 1262 | if (size > 0) |
| 1263 | { |
| 1264 | if (!fwrite (data, size, sizeof(char), con_info->fp)) |
| 1265 | return MHD_NO; |
| 1266 | } |
| 1267 | If this point has been reached, everything worked well for this |
| 1268 | iteration and the response can be set to success again. If the upload |
| 1269 | has finished, this iterator function will not be called again. |
| 1270 | con_info->answerstring = completepage; |
| 1271 | con_info->answercode = MHD_HTTP_OK; |
| 1272 | |
| 1273 | return MHD_YES; |
| 1274 | } |
| 1275 | The new client was registered when the postprocessor was created. |
| 1276 | Likewise, we unregister the client on destroying the postprocessor when |
| 1277 | the request is completed. |
| 1278 | void request_completed (void *cls, struct MHD_Connection *connection, |
| 1279 | void **con_cls, |
| 1280 | enum MHD_RequestTerminationCode toe) |
| 1281 | { |
| 1282 | struct connection_info_struct *con_info = *con_cls; |
| 1283 | |
| 1284 | if (NULL == con_info) return; |
| 1285 | |
| 1286 | if (con_info->connectiontype == POST) |
| 1287 | { |
| 1288 | if (NULL != con_info->postprocessor) |
| 1289 | { |
| 1290 | MHD_destroy_post_processor (con_info->postprocessor); |
| 1291 | nr_of_uploading_clients--; |
| 1292 | } |
| 1293 | |
| 1294 | if (con_info->fp) fclose (con_info->fp); |
| 1295 | } |
| 1296 | |
| 1297 | free (con_info); |
| 1298 | *con_cls = NULL; |
| 1299 | } |
| 1300 | This is essentially the whole example `largepost.c'. |
| 1301 | |
| 1302 | Remarks |
| 1303 | ======= |
| 1304 | |
| 1305 | Now that the clients are able to create files on the server, security |
| 1306 | aspects are becoming even more important than before. Aside from proper |
| 1307 | client authentication, the server should always make sure explicitly |
| 1308 | that no files will be created outside of a dedicated upload directory. |
| 1309 | In particular, filenames must be checked to not contain strings like |
| 1310 | "../". |
| 1311 | |
| 1312 | |
| 1313 | File: libmicrohttpd-tutorial.info, Node: Session management, Next: Adding a layer of security, Prev: Improved processing of POST data, Up: Top |
| 1314 | |
| 1315 | 8 Session management |
| 1316 | ******************** |
| 1317 | |
| 1318 | This chapter discusses how one should manage sessions, that is, share |
| 1319 | state between multiple HTTP requests from the same user. We use a |
| 1320 | simple example where the user submits multiple forms and the server is |
| 1321 | supposed to accumulate state from all of these forms. Naturally, as |
| 1322 | this is a network protocol, our session mechanism must support having |
| 1323 | many users with many concurrent sessions at the same time. |
| 1324 | |
| 1325 | In order to track users, we use a simple session cookie. A session |
| 1326 | cookie expires when the user closes the browser. Changing from session |
| 1327 | cookies to persistent cookies only requires adding an expiration time |
| 1328 | to the cookie. The server creates a fresh session cookie whenever a |
| 1329 | request without a cookie is received, or if the supplied session cookie |
| 1330 | is not known to the server. |
| 1331 | |
| 1332 | Looking up the cookie |
| 1333 | ===================== |
| 1334 | |
| 1335 | Since MHD parses the HTTP cookie header for us, looking up an existing |
| 1336 | cookie is straightforward: |
| 1337 | |
| 1338 | FIXME. |
| 1339 | |
| 1340 | Here, FIXME is the name we chose for our session cookie. |
| 1341 | |
| 1342 | Setting the cookie header |
| 1343 | ========================= |
| 1344 | |
| 1345 | MHD requires the user to provide the full cookie format string in order |
| 1346 | to set cookies. In order to generate a unique cookie, our example |
| 1347 | creates a random 64-character text string to be used as the value of |
| 1348 | the cookie: |
| 1349 | |
| 1350 | FIXME. |
| 1351 | |
| 1352 | Given this cookie value, we can then set the cookie header in our |
| 1353 | HTTP response as follows: |
| 1354 | |
| 1355 | FIXME. |
| 1356 | |
| 1357 | Remark: Session expiration |
| 1358 | ========================== |
| 1359 | |
| 1360 | It is of course possible that clients stop their interaction with the |
| 1361 | server at any time. In order to avoid using too much storage, the |
| 1362 | server must thus discard inactive sessions at some point. Our example |
| 1363 | implements this by discarding inactive sessions after a certain amount |
| 1364 | of time. Alternatively, the implementation may limit the total number |
| 1365 | of active sessions. Which bounds are used for idle sessions or the |
| 1366 | total number of sessions obviously depends largely on the type of the |
| 1367 | application and available server resources. |
| 1368 | |
| 1369 | Example code |
| 1370 | ============ |
| 1371 | |
| 1372 | A sample application implementing a website with multiple forms (which |
| 1373 | are dynamically created using values from previous POST requests from |
| 1374 | the same session) is available as the example `sessions.c'. |
| 1375 | |
| 1376 | Note that the example uses a simple, $O(n)$ linked list traversal to |
| 1377 | look up sessions and to expire old sessions. Using a hash table and a |
| 1378 | heap would be more appropriate if a large number of concurrent sessions |
| 1379 | is expected. |
| 1380 | |
| 1381 | Remarks |
| 1382 | ======= |
| 1383 | |
| 1384 | Naturally, it is quite conceivable to store session data in a database |
| 1385 | instead of in memory. Still, having mechanisms to expire data |
| 1386 | associated with long-time idle sessions (where the business process has |
| 1387 | still not finished) is likely a good idea. |
| 1388 | |
| 1389 | |
| 1390 | File: libmicrohttpd-tutorial.info, Node: Adding a layer of security, Next: Bibliography, Prev: Session management, Up: Top |
| 1391 | |
| 1392 | 9 Adding a layer of security |
| 1393 | **************************** |
| 1394 | |
| 1395 | We left the basic authentication chapter with the unsatisfactory |
| 1396 | conclusion that any traffic, including the credentials, could be |
| 1397 | intercepted by anyone between the browser client and the server. |
| 1398 | Protecting the data while it is sent over unsecured lines will be the |
| 1399 | goal of this chapter. |
| 1400 | |
| 1401 | Since version 0.4, the _MHD_ library includes support for encrypting |
| 1402 | the traffic by employing SSL/TSL. If _GNU libmicrohttpd_ has been |
| 1403 | configured to support these, encryption and decryption can be applied |
| 1404 | transparently on the data being sent, with only minimal changes to the |
| 1405 | actual source code of the example. |
| 1406 | |
| 1407 | Preparation |
| 1408 | =========== |
| 1409 | |
| 1410 | First, a private key for the server will be generated. With this key, |
| 1411 | the server will later be able to authenticate itself to the |
| 1412 | client--preventing anyone else from stealing the password by faking its |
| 1413 | identity. The _OpenSSL_ suite, which is available on many operating |
| 1414 | systems, can generate such a key. For the scope of this tutorial, we |
| 1415 | will be content with a 1024 bit key: |
| 1416 | > openssl genrsa -out server.key 1024 |
| 1417 | In addition to the key, a certificate describing the server in human |
| 1418 | readable tokens is also needed. This certificate will be attested with |
| 1419 | our aforementioned key. In this way, we obtain a self-signed |
| 1420 | certificate, valid for one year. |
| 1421 | |
| 1422 | > openssl req -days 365 -out server.pem -new -x509 -key server.key |
| 1423 | To avoid unnecessary error messages in the browser, the certificate |
| 1424 | needs to have a name that matches the _URI_, for example, "localhost" |
| 1425 | or the domain. If you plan to have a publicly reachable server, you |
| 1426 | will need to ask a trusted third party, called _Certificate Authority_, |
| 1427 | or _CA_, to attest the certificate for you. This way, any visitor can |
| 1428 | make sure the server's identity is real. |
| 1429 | |
| 1430 | Whether the server's certificate is signed by us or a third party, |
| 1431 | once it has been accepted by the client, both sides will be |
| 1432 | communicating over encrypted channels. From this point on, it is the |
| 1433 | client's turn to authenticate itself. But this has already been |
| 1434 | implemented in the basic authentication scheme. |
| 1435 | |
| 1436 | Changing the source code |
| 1437 | ======================== |
| 1438 | |
| 1439 | We merely have to extend the server program so that it loads the two |
| 1440 | files into memory, |
| 1441 | |
| 1442 | int |
| 1443 | main () |
| 1444 | { |
| 1445 | struct MHD_Daemon *daemon; |
| 1446 | char *key_pem; |
| 1447 | char *cert_pem; |
| 1448 | |
| 1449 | key_pem = load_file (SERVERKEYFILE); |
| 1450 | cert_pem = load_file (SERVERCERTFILE); |
| 1451 | |
| 1452 | if ((key_pem == NULL) || (cert_pem == NULL)) |
| 1453 | { |
| 1454 | printf ("The key/certificate files could not be read.\n"); |
| 1455 | return 1; |
| 1456 | } |
| 1457 | and then we point the _MHD_ daemon to it upon initalization. |
| 1458 | |
| 1459 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_SSL, |
| 1460 | PORT, NULL, NULL, |
| 1461 | &answer_to_connection, NULL, |
| 1462 | MHD_OPTION_HTTPS_MEM_KEY, key_pem, |
| 1463 | MHD_OPTION_HTTPS_MEM_CERT, cert_pem, |
| 1464 | MHD_OPTION_END); |
| 1465 | |
| 1466 | if (NULL == daemon) |
| 1467 | { |
| 1468 | printf ("%s\n", cert_pem); |
| 1469 | |
| 1470 | free (key_pem); |
| 1471 | free (cert_pem); |
| 1472 | |
| 1473 | return 1; |
| 1474 | } |
| 1475 | The rest consists of little new besides some additional memory |
| 1476 | cleanups. |
| 1477 | |
| 1478 | getchar (); |
| 1479 | |
| 1480 | MHD_stop_daemon (daemon); |
| 1481 | free (key_pem); |
| 1482 | free (cert_pem); |
| 1483 | |
| 1484 | return 0; |
| 1485 | } |
| 1486 | The rather unexciting file loader can be found in the complete example |
| 1487 | `tlsauthentication.c'. |
| 1488 | |
| 1489 | Remarks |
| 1490 | ======= |
| 1491 | |
| 1492 | * While the standard _HTTP_ port is 80, it is 443 for _HTTPS_. The |
| 1493 | common internet browsers assume standard _HTTP_ if they are asked |
| 1494 | to access other ports than these. Therefore, you will have to type |
| 1495 | `https://localhost:8888' explicitly when you test the example, or |
| 1496 | the browser will not know how to handle the answer properly. |
| 1497 | |
| 1498 | * The remaining weak point is the question how the server will be |
| 1499 | trusted initially. Either a _CA_ signs the certificate or the |
| 1500 | client obtains the key over secure means. Anyway, the clients have |
| 1501 | to be aware (or configured) that they should not accept |
| 1502 | certificates of unknown origin. |
| 1503 | |
| 1504 | * The introduced method of certificates makes it mandatory to set an |
| 1505 | expiration date--making it less feasible to hardcode certificates |
| 1506 | in embedded devices. |
| 1507 | |
| 1508 | * The cryptographic facilities consume memory space and computing |
| 1509 | time. For this reason, websites usually consists both of |
| 1510 | uncritically _HTTP_ parts and secured _HTTPS_. |
| 1511 | |
| 1512 | |
| 1513 | Client authentication |
| 1514 | ===================== |
| 1515 | |
| 1516 | You can also use MHD to authenticate the client via SSL/TLS certificates |
| 1517 | (as an alternative to using the password-based Basic or Digest |
| 1518 | authentication). To do this, you will need to link your application |
| 1519 | against _gnutls_. Next, when you start the MHD daemon, you must |
| 1520 | specify the root CA that you're willing to trust: |
| 1521 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_SSL, |
| 1522 | PORT, NULL, NULL, |
| 1523 | &answer_to_connection, NULL, |
| 1524 | MHD_OPTION_HTTPS_MEM_KEY, key_pem, |
| 1525 | MHD_OPTION_HTTPS_MEM_CERT, cert_pem, |
| 1526 | MHD_OPTION_HTTPS_MEM_TRUST, root_ca_pem, |
| 1527 | MHD_OPTION_END); |
| 1528 | |
| 1529 | With this, you can then obtain client certificates for each session. |
| 1530 | In order to obtain the identity of the client, you first need to obtain |
| 1531 | the raw GnuTLS session handle from _MHD_ using |
| 1532 | `MHD_get_connection_info'. |
| 1533 | |
| 1534 | #include <gnutls/gnutls.h> |
| 1535 | #include <gnutls/x509.h> |
| 1536 | |
| 1537 | gnutls_session_t tls_session; |
| 1538 | union MHD_ConnectionInfo *ci; |
| 1539 | |
| 1540 | ci = MHD_get_connection_info (connection, |
| 1541 | MHD_CONNECTION_INFO_GNUTLS_SESSION); |
| 1542 | tls_session = ci->tls_session; |
| 1543 | |
| 1544 | You can then extract the client certificate: |
| 1545 | |
| 1546 | /** |
| 1547 | * Get the client's certificate |
| 1548 | * |
| 1549 | * @param tls_session the TLS session |
| 1550 | * @return NULL if no valid client certificate could be found, a pointer |
| 1551 | * to the certificate if found |
| 1552 | */ |
| 1553 | static gnutls_x509_crt_t |
| 1554 | get_client_certificate (gnutls_session_t tls_session) |
| 1555 | { |
| 1556 | unsigned int listsize; |
| 1557 | const gnutls_datum_t * pcert; |
| 1558 | gnutls_certificate_status_t client_cert_status; |
| 1559 | gnutls_x509_crt_t client_cert; |
| 1560 | |
| 1561 | if (tls_session == NULL) |
| 1562 | return NULL; |
| 1563 | if (gnutls_certificate_verify_peers2(tls_session, |
| 1564 | &client_cert_status)) |
| 1565 | return NULL; |
| 1566 | pcert = gnutls_certificate_get_peers(tls_session, |
| 1567 | &listsize); |
| 1568 | if ( (pcert == NULL) || |
| 1569 | (listsize == 0)) |
| 1570 | { |
| 1571 | fprintf (stderr, |
| 1572 | "Failed to retrieve client certificate chain\n"); |
| 1573 | return NULL; |
| 1574 | } |
| 1575 | if (gnutls_x509_crt_init(&client_cert)) |
| 1576 | { |
| 1577 | fprintf (stderr, |
| 1578 | "Failed to initialize client certificate\n"); |
| 1579 | return NULL; |
| 1580 | } |
| 1581 | /* Note that by passing values between 0 and listsize here, you |
| 1582 | can get access to the CA's certs */ |
| 1583 | if (gnutls_x509_crt_import(client_cert, |
| 1584 | &pcert[0], |
| 1585 | GNUTLS_X509_FMT_DER)) |
| 1586 | { |
| 1587 | fprintf (stderr, |
| 1588 | "Failed to import client certificate\n"); |
| 1589 | gnutls_x509_crt_deinit(client_cert); |
| 1590 | return NULL; |
| 1591 | } |
| 1592 | return client_cert; |
| 1593 | } |
| 1594 | |
| 1595 | Using the client certificate, you can then get the client's |
| 1596 | distinguished name and alternative names: |
| 1597 | |
| 1598 | /** |
| 1599 | * Get the distinguished name from the client's certificate |
| 1600 | * |
| 1601 | * @param client_cert the client certificate |
| 1602 | * @return NULL if no dn or certificate could be found, a pointer |
| 1603 | * to the dn if found |
| 1604 | */ |
| 1605 | char * |
| 1606 | cert_auth_get_dn(gnutls_x509_crt_c client_cert) |
| 1607 | { |
| 1608 | char* buf; |
| 1609 | size_t lbuf; |
| 1610 | |
| 1611 | lbuf = 0; |
| 1612 | gnutls_x509_crt_get_dn(client_cert, NULL, &lbuf); |
| 1613 | buf = malloc(lbuf); |
| 1614 | if (buf == NULL) |
| 1615 | { |
| 1616 | fprintf (stderr, |
| 1617 | "Failed to allocate memory for certificate dn\n"); |
| 1618 | return NULL; |
| 1619 | } |
| 1620 | gnutls_x509_crt_get_dn(client_cert, buf, &lbuf); |
| 1621 | return buf; |
| 1622 | } |
| 1623 | |
| 1624 | |
| 1625 | /** |
| 1626 | * Get the alternative name of specified type from the client's certificate |
| 1627 | * |
| 1628 | * @param client_cert the client certificate |
| 1629 | * @param nametype The requested name type |
| 1630 | * @param index The position of the alternative name if multiple names are |
| 1631 | * matching the requested type, 0 for the first matching name |
| 1632 | * @return NULL if no matching alternative name could be found, a pointer |
| 1633 | * to the alternative name if found |
| 1634 | */ |
| 1635 | char * |
| 1636 | MHD_cert_auth_get_alt_name(gnutls_x509_crt_t client_cert, |
| 1637 | int nametype, |
| 1638 | unsigned int index) |
| 1639 | { |
| 1640 | char* buf; |
| 1641 | size_t lbuf; |
| 1642 | unsigned int seq; |
| 1643 | unsigned int subseq; |
| 1644 | unsigned int type; |
| 1645 | int result; |
| 1646 | |
| 1647 | subseq = 0; |
| 1648 | for (seq=0;;seq++) |
| 1649 | { |
| 1650 | lbuf = 0; |
| 1651 | result = gnutls_x509_crt_get_subject_alt_name2(client_cert, seq, NULL, &lbuf, |
| 1652 | &type, NULL); |
| 1653 | if (result == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) |
| 1654 | return NULL; |
| 1655 | if (nametype != (int) type) |
| 1656 | continue; |
| 1657 | if (subseq == index) |
| 1658 | break; |
| 1659 | subseq++; |
| 1660 | } |
| 1661 | buf = malloc(lbuf); |
| 1662 | if (buf == NULL) |
| 1663 | { |
| 1664 | fprintf (stderr, |
| 1665 | "Failed to allocate memory for certificate alt name\n"); |
| 1666 | return NULL; |
| 1667 | } |
| 1668 | result = gnutls_x509_crt_get_subject_alt_name2(client_cert, |
| 1669 | seq, |
| 1670 | buf, |
| 1671 | &lbuf, |
| 1672 | NULL, NULL); |
| 1673 | if (result != nametype) |
| 1674 | { |
| 1675 | fprintf (stderr, |
| 1676 | "Unexpected return value from gnutls: %d\n", |
| 1677 | result); |
| 1678 | free (buf); |
| 1679 | return NULL; |
| 1680 | } |
| 1681 | return buf; |
| 1682 | } |
| 1683 | |
| 1684 | Finally, you should release the memory associated with the client |
| 1685 | certificate: |
| 1686 | |
| 1687 | gnutls_x509_crt_deinit (client_cert); |
| 1688 | |
| 1689 | Using TLS Server Name Indication (SNI) |
| 1690 | ====================================== |
| 1691 | |
| 1692 | SNI enables hosting multiple domains under one IP address with TLS. So |
| 1693 | SNI is the TLS-equivalent of virtual hosting. To use SNI with MHD, you |
| 1694 | need at least GnuTLS 3.0. The main change compared to the simple |
| 1695 | hosting of one domain is that you need to provide a callback instead of |
| 1696 | the key and certificate. For example, when you start the MHD daemon, |
| 1697 | you could do this: |
| 1698 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_SSL, |
| 1699 | PORT, NULL, NULL, |
| 1700 | &answer_to_connection, NULL, |
| 1701 | MHD_OPTION_HTTPS_CERT_CALLBACK, &sni_callback, |
| 1702 | MHD_OPTION_END); |
| 1703 | Here, `sni_callback' is the name of a function that you will have to |
| 1704 | implement to retrieve the X.509 certificate for an incoming connection. |
| 1705 | The callback has type `gnutls_certificate_retrieve_function2' and is |
| 1706 | documented in the GnuTLS API for the |
| 1707 | `gnutls_certificate_set_retrieve_function2' as follows: |
| 1708 | |
| 1709 | -- Function Pointer: int *gnutls_certificate_retrieve_function2 |
| 1710 | (gnutls_session_t, const gnutls_datum_t* req_ca_dn, int |
| 1711 | nreqs, const gnutls_pk_algorithm_t* pk_algos, int |
| 1712 | pk_algos_length, gnutls_pcert_st** pcert, unsigned int |
| 1713 | *pcert_length, gnutls_privkey_t * pkey) |
| 1714 | REQ_CA_CERT |
| 1715 | is only used in X.509 certificates. Contains a list with the |
| 1716 | CA names that the server considers trusted. Normally we |
| 1717 | should send a certificate that is signed by one of these CAs. |
| 1718 | These names are DER encoded. To get a more meaningful value |
| 1719 | use the function `gnutls_x509_rdn_get()'. |
| 1720 | |
| 1721 | PK_ALGOS |
| 1722 | contains a list with server’s acceptable signature |
| 1723 | algorithms. The certificate returned should support the |
| 1724 | server’s given algorithms. |
| 1725 | |
| 1726 | PCERT |
| 1727 | should contain a single certificate and public or a list of |
| 1728 | them. |
| 1729 | |
| 1730 | PCERT_LENGTH |
| 1731 | is the size of the previous list. |
| 1732 | |
| 1733 | PKEY |
| 1734 | is the private key. |
| 1735 | |
| 1736 | A possible implementation of this callback would look like this: |
| 1737 | |
| 1738 | struct Hosts |
| 1739 | { |
| 1740 | struct Hosts *next; |
| 1741 | const char *hostname; |
| 1742 | gnutls_pcert_st pcrt; |
| 1743 | gnutls_privkey_t key; |
| 1744 | }; |
| 1745 | |
| 1746 | static struct Hosts *hosts; |
| 1747 | |
| 1748 | int |
| 1749 | sni_callback (gnutls_session_t session, |
| 1750 | const gnutls_datum_t* req_ca_dn, |
| 1751 | int nreqs, |
| 1752 | const gnutls_pk_algorithm_t* pk_algos, |
| 1753 | int pk_algos_length, |
| 1754 | gnutls_pcert_st** pcert, |
| 1755 | unsigned int *pcert_length, |
| 1756 | gnutls_privkey_t * pkey) |
| 1757 | { |
| 1758 | char name[256]; |
| 1759 | size_t name_len; |
| 1760 | struct Hosts *host; |
| 1761 | unsigned int type; |
| 1762 | |
| 1763 | name_len = sizeof (name); |
| 1764 | if (GNUTLS_E_SUCCESS != |
| 1765 | gnutls_server_name_get (session, |
| 1766 | name, |
| 1767 | &name_len, |
| 1768 | &type, |
| 1769 | 0 /* index */)) |
| 1770 | return -1; |
| 1771 | for (host = hosts; NULL != host; host = host->next) |
| 1772 | if (0 == strncmp (name, host->hostname, name_len)) |
| 1773 | break; |
| 1774 | if (NULL == host) |
| 1775 | { |
| 1776 | fprintf (stderr, |
| 1777 | "Need certificate for %.*s\n", |
| 1778 | (int) name_len, |
| 1779 | name); |
| 1780 | return -1; |
| 1781 | } |
| 1782 | fprintf (stderr, |
| 1783 | "Returning certificate for %.*s\n", |
| 1784 | (int) name_len, |
| 1785 | name); |
| 1786 | *pkey = host->key; |
| 1787 | *pcert_length = 1; |
| 1788 | *pcert = &host->pcrt; |
| 1789 | return 0; |
| 1790 | } |
| 1791 | |
| 1792 | Note that MHD cannot offer passing a closure or any other additional |
| 1793 | information to this callback, as the GnuTLS API unfortunately does not |
| 1794 | permit this at this point. |
| 1795 | |
| 1796 | The `hosts' list can be initialized by loading the private keys and |
| 1797 | X.509 certificats from disk as follows: |
| 1798 | |
| 1799 | static void |
| 1800 | load_keys(const char *hostname, |
| 1801 | const char *CERT_FILE, |
| 1802 | const char *KEY_FILE) |
| 1803 | { |
| 1804 | int ret; |
| 1805 | gnutls_datum_t data; |
| 1806 | struct Hosts *host; |
| 1807 | |
| 1808 | host = malloc (sizeof (struct Hosts)); |
| 1809 | host->hostname = hostname; |
| 1810 | host->next = hosts; |
| 1811 | hosts = host; |
| 1812 | |
| 1813 | ret = gnutls_load_file (CERT_FILE, &data); |
| 1814 | if (ret < 0) |
| 1815 | { |
| 1816 | fprintf (stderr, |
| 1817 | "*** Error loading certificate file %s.\n", |
| 1818 | CERT_FILE); |
| 1819 | exit(1); |
| 1820 | } |
| 1821 | ret = |
| 1822 | gnutls_pcert_import_x509_raw (&host->pcrt, &data, GNUTLS_X509_FMT_PEM, |
| 1823 | 0); |
| 1824 | if (ret < 0) |
| 1825 | { |
| 1826 | fprintf(stderr, |
| 1827 | "*** Error loading certificate file: %s\n", |
| 1828 | gnutls_strerror (ret)); |
| 1829 | exit(1); |
| 1830 | } |
| 1831 | gnutls_free (data.data); |
| 1832 | |
| 1833 | ret = gnutls_load_file (KEY_FILE, &data); |
| 1834 | if (ret < 0) |
| 1835 | { |
| 1836 | fprintf (stderr, |
| 1837 | "*** Error loading key file %s.\n", |
| 1838 | KEY_FILE); |
| 1839 | exit(1); |
| 1840 | } |
| 1841 | |
| 1842 | gnutls_privkey_init (&host->key); |
| 1843 | ret = |
| 1844 | gnutls_privkey_import_x509_raw (host->key, |
| 1845 | &data, GNUTLS_X509_FMT_PEM, |
| 1846 | NULL, 0); |
| 1847 | if (ret < 0) |
| 1848 | { |
| 1849 | fprintf (stderr, |
| 1850 | "*** Error loading key file: %s\n", |
| 1851 | gnutls_strerror (ret)); |
| 1852 | exit(1); |
| 1853 | } |
| 1854 | gnutls_free (data.data); |
| 1855 | } |
| 1856 | |
| 1857 | The code above was largely lifted from GnuTLS. You can find other |
| 1858 | methods for initializing certificates and keys in the GnuTLS manual and |
| 1859 | source code. |
| 1860 | |
| 1861 | |
| 1862 | File: libmicrohttpd-tutorial.info, Node: Bibliography, Next: License text, Prev: Adding a layer of security, Up: Top |
| 1863 | |
| 1864 | Appendix A Bibliography |
| 1865 | *********************** |
| 1866 | |
| 1867 | API reference |
| 1868 | ============= |
| 1869 | |
| 1870 | * The _GNU libmicrohttpd_ manual by Marco Maggi and Christian |
| 1871 | Grothoff 2008 `http://gnunet.org/libmicrohttpd/microhttpd.html' |
| 1872 | |
| 1873 | * All referenced RFCs can be found on the website of _The Internet |
| 1874 | Engineering Task Force_ `http://www.ietf.org/' |
| 1875 | |
| 1876 | * _RFC 2616_: Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and |
| 1877 | T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1", RFC |
| 1878 | 2016, January 1997. |
| 1879 | |
| 1880 | * _RFC 2617_: Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, |
| 1881 | S., Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: |
| 1882 | Basic and Digest Access Authentication", RFC 2617, June 1999. |
| 1883 | |
| 1884 | * A well-structured _HTML_ reference can be found on |
| 1885 | `http://www.echoecho.com/html.htm' |
| 1886 | |
| 1887 | For those readers understanding German or French, there is an |
| 1888 | excellent document both for learning _HTML_ and for reference, |
| 1889 | whose English version unfortunately has been discontinued. |
| 1890 | `http://de.selfhtml.org/' and `http://fr.selfhtml.org/' |
| 1891 | |
| 1892 | |
| 1893 | |
| 1894 | File: libmicrohttpd-tutorial.info, Node: License text, Next: Example programs, Prev: Bibliography, Up: Top |
| 1895 | |
| 1896 | Appendix B GNU Free Documentation License |
| 1897 | ***************************************** |
| 1898 | |
| 1899 | Version 1.3, 3 November 2008 |
| 1900 | |
| 1901 | Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. |
| 1902 | `http://fsf.org/' |
| 1903 | |
| 1904 | Everyone is permitted to copy and distribute verbatim copies |
| 1905 | of this license document, but changing it is not allowed. |
| 1906 | |
| 1907 | 0. PREAMBLE |
| 1908 | |
| 1909 | The purpose of this License is to make a manual, textbook, or other |
| 1910 | functional and useful document "free" in the sense of freedom: to |
| 1911 | assure everyone the effective freedom to copy and redistribute it, |
| 1912 | with or without modifying it, either commercially or |
| 1913 | noncommercially. Secondarily, this License preserves for the |
| 1914 | author and publisher a way to get credit for their work, while not |
| 1915 | being considered responsible for modifications made by others. |
| 1916 | |
| 1917 | This License is a kind of "copyleft", which means that derivative |
| 1918 | works of the document must themselves be free in the same sense. |
| 1919 | It complements the GNU General Public License, which is a copyleft |
| 1920 | license designed for free software. |
| 1921 | |
| 1922 | We have designed this License in order to use it for manuals for |
| 1923 | free software, because free software needs free documentation: a |
| 1924 | free program should come with manuals providing the same freedoms |
| 1925 | that the software does. But this License is not limited to |
| 1926 | software manuals; it can be used for any textual work, regardless |
| 1927 | of subject matter or whether it is published as a printed book. |
| 1928 | We recommend this License principally for works whose purpose is |
| 1929 | instruction or reference. |
| 1930 | |
| 1931 | 1. APPLICABILITY AND DEFINITIONS |
| 1932 | |
| 1933 | This License applies to any manual or other work, in any medium, |
| 1934 | that contains a notice placed by the copyright holder saying it |
| 1935 | can be distributed under the terms of this License. Such a notice |
| 1936 | grants a world-wide, royalty-free license, unlimited in duration, |
| 1937 | to use that work under the conditions stated herein. The |
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| 1939 | of the public is a licensee, and is addressed as "you". You |
| 1940 | accept the license if you copy, modify or distribute the work in a |
| 1941 | way requiring permission under copyright law. |
| 1942 | |
| 1943 | A "Modified Version" of the Document means any work containing the |
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| 1945 | modifications and/or translated into another language. |
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| 1947 | A "Secondary Section" is a named appendix or a front-matter section |
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| 2023 | 2. VERBATIM COPYING |
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| 2025 | You may copy and distribute the Document in any medium, either |
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| 2039 | 3. COPYING IN QUANTITY |
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| 2041 | If you publish printed copies (or copies in media that commonly |
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| 2055 | If the required texts for either cover are too voluminous to fit |
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| 2079 | 4. MODIFICATIONS |
| 2080 | |
| 2081 | You may copy and distribute a Modified Version of the Document |
| 2082 | under the conditions of sections 2 and 3 above, provided that you |
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| 2087 | things in the Modified Version: |
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| 2089 | A. Use in the Title Page (and on the covers, if any) a title |
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| 2121 | |
| 2122 | I. Preserve the section Entitled "History", Preserve its Title, |
| 2123 | and add to it an item stating at least the title, year, new |
| 2124 | authors, and publisher of the Modified Version as given on |
| 2125 | the Title Page. If there is no section Entitled "History" in |
| 2126 | the Document, create one stating the title, year, authors, |
| 2127 | and publisher of the Document as given on its Title Page, |
| 2128 | then add an item describing the Modified Version as stated in |
| 2129 | the previous sentence. |
| 2130 | |
| 2131 | J. Preserve the network location, if any, given in the Document |
| 2132 | for public access to a Transparent copy of the Document, and |
| 2133 | likewise the network locations given in the Document for |
| 2134 | previous versions it was based on. These may be placed in |
| 2135 | the "History" section. You may omit a network location for a |
| 2136 | work that was published at least four years before the |
| 2137 | Document itself, or if the original publisher of the version |
| 2138 | it refers to gives permission. |
| 2139 | |
| 2140 | K. For any section Entitled "Acknowledgements" or "Dedications", |
| 2141 | Preserve the Title of the section, and preserve in the |
| 2142 | section all the substance and tone of each of the contributor |
| 2143 | acknowledgements and/or dedications given therein. |
| 2144 | |
| 2145 | L. Preserve all the Invariant Sections of the Document, |
| 2146 | unaltered in their text and in their titles. Section numbers |
| 2147 | or the equivalent are not considered part of the section |
| 2148 | titles. |
| 2149 | |
| 2150 | M. Delete any section Entitled "Endorsements". Such a section |
| 2151 | may not be included in the Modified Version. |
| 2152 | |
| 2153 | N. Do not retitle any existing section to be Entitled |
| 2154 | "Endorsements" or to conflict in title with any Invariant |
| 2155 | Section. |
| 2156 | |
| 2157 | O. Preserve any Warranty Disclaimers. |
| 2158 | |
| 2159 | If the Modified Version includes new front-matter sections or |
| 2160 | appendices that qualify as Secondary Sections and contain no |
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| 2162 | designate some or all of these sections as invariant. To do this, |
| 2163 | add their titles to the list of Invariant Sections in the Modified |
| 2164 | Version's license notice. These titles must be distinct from any |
| 2165 | other section titles. |
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| 2167 | You may add a section Entitled "Endorsements", provided it contains |
| 2168 | nothing but endorsements of your Modified Version by various |
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| 2170 | has been approved by an organization as the authoritative |
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| 2173 | You may add a passage of up to five words as a Front-Cover Text, |
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| 2178 | Document already includes a cover text for the same cover, |
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| 2184 | The author(s) and publisher(s) of the Document do not by this |
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| 2187 | |
| 2188 | 5. COMBINING DOCUMENTS |
| 2189 | |
| 2190 | You may combine the Document with other documents released under |
| 2191 | this License, under the terms defined in section 4 above for |
| 2192 | modified versions, provided that you include in the combination |
| 2193 | all of the Invariant Sections of all of the original documents, |
| 2194 | unmodified, and list them all as Invariant Sections of your |
| 2195 | combined work in its license notice, and that you preserve all |
| 2196 | their Warranty Disclaimers. |
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| 2198 | The combined work need only contain one copy of this License, and |
| 2199 | multiple identical Invariant Sections may be replaced with a single |
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| 2204 | unique number. Make the same adjustment to the section titles in |
| 2205 | the list of Invariant Sections in the license notice of the |
| 2206 | combined work. |
| 2207 | |
| 2208 | In the combination, you must combine any sections Entitled |
| 2209 | "History" in the various original documents, forming one section |
| 2210 | Entitled "History"; likewise combine any sections Entitled |
| 2211 | "Acknowledgements", and any sections Entitled "Dedications". You |
| 2212 | must delete all sections Entitled "Endorsements." |
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| 2214 | 6. COLLECTIONS OF DOCUMENTS |
| 2215 | |
| 2216 | You may make a collection consisting of the Document and other |
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| 2218 | copies of this License in the various documents with a single copy |
| 2219 | that is included in the collection, provided that you follow the |
| 2220 | rules of this License for verbatim copying of each of the |
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| 2223 | You may extract a single document from such a collection, and |
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| 2226 | this License in all other respects regarding verbatim copying of |
| 2227 | that document. |
| 2228 | |
| 2229 | 7. AGGREGATION WITH INDEPENDENT WORKS |
| 2230 | |
| 2231 | A compilation of the Document or its derivatives with other |
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| 2234 | copyright resulting from the compilation is not used to limit the |
| 2235 | legal rights of the compilation's users beyond what the individual |
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| 2240 | If the Cover Text requirement of section 3 is applicable to these |
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| 2246 | the whole aggregate. |
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| 2248 | 8. TRANSLATION |
| 2249 | |
| 2250 | Translation is considered a kind of modification, so you may |
| 2251 | distribute translations of the Document under the terms of section |
| 2252 | 4. Replacing Invariant Sections with translations requires special |
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| 2254 | translations of some or all Invariant Sections in addition to the |
| 2255 | original versions of these Invariant Sections. You may include a |
| 2256 | translation of this License, and all the license notices in the |
| 2257 | Document, and any Warranty Disclaimers, provided that you also |
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| 2262 | prevail. |
| 2263 | |
| 2264 | If a section in the Document is Entitled "Acknowledgements", |
| 2265 | "Dedications", or "History", the requirement (section 4) to |
| 2266 | Preserve its Title (section 1) will typically require changing the |
| 2267 | actual title. |
| 2268 | |
| 2269 | 9. TERMINATION |
| 2270 | |
| 2271 | You may not copy, modify, sublicense, or distribute the Document |
| 2272 | except as expressly provided under this License. Any attempt |
| 2273 | otherwise to copy, modify, sublicense, or distribute it is void, |
| 2274 | and will automatically terminate your rights under this License. |
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| 2276 | However, if you cease all violation of this License, then your |
| 2277 | license from a particular copyright holder is reinstated (a) |
| 2278 | provisionally, unless and until the copyright holder explicitly |
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| 2283 | Moreover, your license from a particular copyright holder is |
| 2284 | reinstated permanently if the copyright holder notifies you of the |
| 2285 | violation by some reasonable means, this is the first time you have |
| 2286 | received notice of violation of this License (for any work) from |
| 2287 | that copyright holder, and you cure the violation prior to 30 days |
| 2288 | after your receipt of the notice. |
| 2289 | |
| 2290 | Termination of your rights under this section does not terminate |
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| 2293 | not permanently reinstated, receipt of a copy of some or all of |
| 2294 | the same material does not give you any rights to use it. |
| 2295 | |
| 2296 | 10. FUTURE REVISIONS OF THIS LICENSE |
| 2297 | |
| 2298 | The Free Software Foundation may publish new, revised versions of |
| 2299 | the GNU Free Documentation License from time to time. Such new |
| 2300 | versions will be similar in spirit to the present version, but may |
| 2301 | differ in detail to address new problems or concerns. See |
| 2302 | `http://www.gnu.org/copyleft/'. |
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| 2304 | Each version of the License is given a distinguishing version |
| 2305 | number. If the Document specifies that a particular numbered |
| 2306 | version of this License "or any later version" applies to it, you |
| 2307 | have the option of following the terms and conditions either of |
| 2308 | that specified version or of any later version that has been |
| 2309 | published (not as a draft) by the Free Software Foundation. If |
| 2310 | the Document does not specify a version number of this License, |
| 2311 | you may choose any version ever published (not as a draft) by the |
| 2312 | Free Software Foundation. If the Document specifies that a proxy |
| 2313 | can decide which future versions of this License can be used, that |
| 2314 | proxy's public statement of acceptance of a version permanently |
| 2315 | authorizes you to choose that version for the Document. |
| 2316 | |
| 2317 | 11. RELICENSING |
| 2318 | |
| 2319 | "Massive Multiauthor Collaboration Site" (or "MMC Site") means any |
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| 2323 | A "Massive Multiauthor Collaboration" (or "MMC") contained in the |
| 2324 | site means any set of copyrightable works thus published on the MMC |
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| 2327 | "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0 |
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| 2329 | corporation with a principal place of business in San Francisco, |
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| 2331 | published by that same organization. |
| 2332 | |
| 2333 | "Incorporate" means to publish or republish a Document, in whole or |
| 2334 | in part, as part of another Document. |
| 2335 | |
| 2336 | An MMC is "eligible for relicensing" if it is licensed under this |
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| 2338 | License somewhere other than this MMC, and subsequently |
| 2339 | incorporated in whole or in part into the MMC, (1) had no cover |
| 2340 | texts or invariant sections, and (2) were thus incorporated prior |
| 2341 | to November 1, 2008. |
| 2342 | |
| 2343 | The operator of an MMC Site may republish an MMC contained in the |
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| 2345 | 2009, provided the MMC is eligible for relicensing. |
| 2346 | |
| 2347 | |
| 2348 | ADDENDUM: How to use this License for your documents |
| 2349 | ==================================================== |
| 2350 | |
| 2351 | To use this License in a document you have written, include a copy of |
| 2352 | the License in the document and put the following copyright and license |
| 2353 | notices just after the title page: |
| 2354 | |
| 2355 | Copyright (C) YEAR YOUR NAME. |
| 2356 | Permission is granted to copy, distribute and/or modify this document |
| 2357 | under the terms of the GNU Free Documentation License, Version 1.3 |
| 2358 | or any later version published by the Free Software Foundation; |
| 2359 | with no Invariant Sections, no Front-Cover Texts, and no Back-Cover |
| 2360 | Texts. A copy of the license is included in the section entitled ``GNU |
| 2361 | Free Documentation License''. |
| 2362 | |
| 2363 | If you have Invariant Sections, Front-Cover Texts and Back-Cover |
| 2364 | Texts, replace the "with...Texts." line with this: |
| 2365 | |
| 2366 | with the Invariant Sections being LIST THEIR TITLES, with |
| 2367 | the Front-Cover Texts being LIST, and with the Back-Cover Texts |
| 2368 | being LIST. |
| 2369 | |
| 2370 | If you have Invariant Sections without Cover Texts, or some other |
| 2371 | combination of the three, merge those two alternatives to suit the |
| 2372 | situation. |
| 2373 | |
| 2374 | If your document contains nontrivial examples of program code, we |
| 2375 | recommend releasing these examples in parallel under your choice of |
| 2376 | free software license, such as the GNU General Public License, to |
| 2377 | permit their use in free software. |
| 2378 | |
| 2379 | |
| 2380 | File: libmicrohttpd-tutorial.info, Node: Example programs, Prev: License text, Up: Top |
| 2381 | |
| 2382 | Appendix C Example programs |
| 2383 | *************************** |
| 2384 | |
| 2385 | * Menu: |
| 2386 | |
| 2387 | * hellobrowser.c:: |
| 2388 | * logging.c:: |
| 2389 | * responseheaders.c:: |
| 2390 | * basicauthentication.c:: |
| 2391 | * simplepost.c:: |
| 2392 | * largepost.c:: |
| 2393 | * sessions.c:: |
| 2394 | * tlsauthentication.c:: |
| 2395 | |
| 2396 | |
| 2397 | File: libmicrohttpd-tutorial.info, Node: hellobrowser.c, Next: logging.c, Up: Example programs |
| 2398 | |
| 2399 | C.1 hellobrowser.c |
| 2400 | ================== |
| 2401 | |
| 2402 | /* Feel free to use this example code in any way |
| 2403 | you see fit (Public Domain) */ |
| 2404 | |
| 2405 | #include <sys/types.h> |
| 2406 | #ifndef _WIN32 |
| 2407 | #include <sys/select.h> |
| 2408 | #include <sys/socket.h> |
| 2409 | #else |
| 2410 | #include <winsock2.h> |
| 2411 | #endif |
| 2412 | #include <string.h> |
| 2413 | #include <microhttpd.h> |
| 2414 | #include <stdio.h> |
| 2415 | |
| 2416 | #define PORT 8888 |
| 2417 | |
| 2418 | static int |
| 2419 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 2420 | const char *url, const char *method, |
| 2421 | const char *version, const char *upload_data, |
| 2422 | size_t *upload_data_size, void **con_cls) |
| 2423 | { |
| 2424 | const char *page = "<html><body>Hello, browser!</body></html>"; |
| 2425 | struct MHD_Response *response; |
| 2426 | int ret; |
| 2427 | |
| 2428 | response = |
| 2429 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 2430 | MHD_RESPMEM_PERSISTENT); |
| 2431 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 2432 | MHD_destroy_response (response); |
| 2433 | |
| 2434 | return ret; |
| 2435 | } |
| 2436 | |
| 2437 | |
| 2438 | int |
| 2439 | main () |
| 2440 | { |
| 2441 | struct MHD_Daemon *daemon; |
| 2442 | |
| 2443 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 2444 | &answer_to_connection, NULL, MHD_OPTION_END); |
| 2445 | if (NULL == daemon) |
| 2446 | return 1; |
| 2447 | |
| 2448 | (void) getchar (); |
| 2449 | |
| 2450 | MHD_stop_daemon (daemon); |
| 2451 | return 0; |
| 2452 | } |
| 2453 | |
| 2454 | |
| 2455 | File: libmicrohttpd-tutorial.info, Node: logging.c, Next: responseheaders.c, Prev: hellobrowser.c, Up: Example programs |
| 2456 | |
| 2457 | C.2 logging.c |
| 2458 | ============= |
| 2459 | |
| 2460 | /* Feel free to use this example code in any way |
| 2461 | you see fit (Public Domain) */ |
| 2462 | |
| 2463 | #include <sys/types.h> |
| 2464 | #ifndef _WIN32 |
| 2465 | #include <sys/select.h> |
| 2466 | #include <sys/socket.h> |
| 2467 | #else |
| 2468 | #include <winsock2.h> |
| 2469 | #endif |
| 2470 | #include <microhttpd.h> |
| 2471 | #include <stdio.h> |
| 2472 | |
| 2473 | #define PORT 8888 |
| 2474 | |
| 2475 | |
| 2476 | static int |
| 2477 | print_out_key (void *cls, enum MHD_ValueKind kind, const char *key, |
| 2478 | const char *value) |
| 2479 | { |
| 2480 | printf ("%s: %s\n", key, value); |
| 2481 | return MHD_YES; |
| 2482 | } |
| 2483 | |
| 2484 | |
| 2485 | static int |
| 2486 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 2487 | const char *url, const char *method, |
| 2488 | const char *version, const char *upload_data, |
| 2489 | size_t *upload_data_size, void **con_cls) |
| 2490 | { |
| 2491 | printf ("New %s request for %s using version %s\n", method, url, version); |
| 2492 | |
| 2493 | MHD_get_connection_values (connection, MHD_HEADER_KIND, print_out_key, |
| 2494 | NULL); |
| 2495 | |
| 2496 | return MHD_NO; |
| 2497 | } |
| 2498 | |
| 2499 | |
| 2500 | int |
| 2501 | main () |
| 2502 | { |
| 2503 | struct MHD_Daemon *daemon; |
| 2504 | |
| 2505 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 2506 | &answer_to_connection, NULL, MHD_OPTION_END); |
| 2507 | if (NULL == daemon) |
| 2508 | return 1; |
| 2509 | |
| 2510 | (void) getchar (); |
| 2511 | |
| 2512 | MHD_stop_daemon (daemon); |
| 2513 | return 0; |
| 2514 | } |
| 2515 | |
| 2516 | |
| 2517 | File: libmicrohttpd-tutorial.info, Node: responseheaders.c, Next: basicauthentication.c, Prev: logging.c, Up: Example programs |
| 2518 | |
| 2519 | C.3 responseheaders.c |
| 2520 | ===================== |
| 2521 | |
| 2522 | /* Feel free to use this example code in any way |
| 2523 | you see fit (Public Domain) */ |
| 2524 | |
| 2525 | #include <sys/types.h> |
| 2526 | #ifndef _WIN32 |
| 2527 | #include <sys/select.h> |
| 2528 | #include <sys/socket.h> |
| 2529 | #else |
| 2530 | #include <winsock2.h> |
| 2531 | #endif |
| 2532 | #include <microhttpd.h> |
| 2533 | #include <time.h> |
| 2534 | #include <sys/stat.h> |
| 2535 | #include <fcntl.h> |
| 2536 | #include <string.h> |
| 2537 | #include <stdio.h> |
| 2538 | |
| 2539 | #define PORT 8888 |
| 2540 | #define FILENAME "picture.png" |
| 2541 | #define MIMETYPE "image/png" |
| 2542 | |
| 2543 | static int |
| 2544 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 2545 | const char *url, const char *method, |
| 2546 | const char *version, const char *upload_data, |
| 2547 | size_t *upload_data_size, void **con_cls) |
| 2548 | { |
| 2549 | struct MHD_Response *response; |
| 2550 | int fd; |
| 2551 | int ret; |
| 2552 | struct stat sbuf; |
| 2553 | |
| 2554 | if (0 != strcmp (method, "GET")) |
| 2555 | return MHD_NO; |
| 2556 | |
| 2557 | if ( (-1 == (fd = open (FILENAME, O_RDONLY))) || |
| 2558 | (0 != fstat (fd, &sbuf)) ) |
| 2559 | { |
| 2560 | /* error accessing file */ |
| 2561 | if (fd != -1) |
| 2562 | (void) close (fd); |
| 2563 | const char *errorstr = |
| 2564 | "<html><body>An internal server error has occured!\ |
| 2565 | </body></html>"; |
| 2566 | response = |
| 2567 | MHD_create_response_from_buffer (strlen (errorstr), |
| 2568 | (void *) errorstr, |
| 2569 | MHD_RESPMEM_PERSISTENT); |
| 2570 | if (NULL != response) |
| 2571 | { |
| 2572 | ret = |
| 2573 | MHD_queue_response (connection, MHD_HTTP_INTERNAL_SERVER_ERROR, |
| 2574 | response); |
| 2575 | MHD_destroy_response (response); |
| 2576 | |
| 2577 | return ret; |
| 2578 | } |
| 2579 | else |
| 2580 | return MHD_NO; |
| 2581 | } |
| 2582 | response = |
| 2583 | MHD_create_response_from_fd_at_offset (sbuf.st_size, fd, 0); |
| 2584 | MHD_add_response_header (response, "Content-Type", MIMETYPE); |
| 2585 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 2586 | MHD_destroy_response (response); |
| 2587 | |
| 2588 | return ret; |
| 2589 | } |
| 2590 | |
| 2591 | |
| 2592 | int |
| 2593 | main () |
| 2594 | { |
| 2595 | struct MHD_Daemon *daemon; |
| 2596 | |
| 2597 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 2598 | &answer_to_connection, NULL, MHD_OPTION_END); |
| 2599 | if (NULL == daemon) |
| 2600 | return 1; |
| 2601 | |
| 2602 | (void) getchar (); |
| 2603 | |
| 2604 | MHD_stop_daemon (daemon); |
| 2605 | |
| 2606 | return 0; |
| 2607 | } |
| 2608 | |
| 2609 | |
| 2610 | File: libmicrohttpd-tutorial.info, Node: basicauthentication.c, Next: simplepost.c, Prev: responseheaders.c, Up: Example programs |
| 2611 | |
| 2612 | C.4 basicauthentication.c |
| 2613 | ========================= |
| 2614 | |
| 2615 | /* Feel free to use this example code in any way |
| 2616 | you see fit (Public Domain) */ |
| 2617 | |
| 2618 | #include <sys/types.h> |
| 2619 | #ifndef _WIN32 |
| 2620 | #include <sys/select.h> |
| 2621 | #include <sys/socket.h> |
| 2622 | #else |
| 2623 | #include <winsock2.h> |
| 2624 | #endif |
| 2625 | #include <microhttpd.h> |
| 2626 | #include <time.h> |
| 2627 | #include <string.h> |
| 2628 | #include <stdlib.h> |
| 2629 | #include <stdio.h> |
| 2630 | |
| 2631 | #define PORT 8888 |
| 2632 | |
| 2633 | |
| 2634 | static int |
| 2635 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 2636 | const char *url, const char *method, |
| 2637 | const char *version, const char *upload_data, |
| 2638 | size_t *upload_data_size, void **con_cls) |
| 2639 | { |
| 2640 | char *user; |
| 2641 | char *pass; |
| 2642 | int fail; |
| 2643 | int ret; |
| 2644 | struct MHD_Response *response; |
| 2645 | |
| 2646 | if (0 != strcmp (method, "GET")) |
| 2647 | return MHD_NO; |
| 2648 | if (NULL == *con_cls) |
| 2649 | { |
| 2650 | *con_cls = connection; |
| 2651 | return MHD_YES; |
| 2652 | } |
| 2653 | pass = NULL; |
| 2654 | user = MHD_basic_auth_get_username_password (connection, &pass); |
| 2655 | fail = ( (user == NULL) || |
| 2656 | (0 != strcmp (user, "root")) || |
| 2657 | (0 != strcmp (pass, "pa$$w0rd") ) ); |
| 2658 | if (user != NULL) free (user); |
| 2659 | if (pass != NULL) free (pass); |
| 2660 | if (fail) |
| 2661 | { |
| 2662 | const char *page = "<html><body>Go away.</body></html>"; |
| 2663 | response = |
| 2664 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 2665 | MHD_RESPMEM_PERSISTENT); |
| 2666 | ret = MHD_queue_basic_auth_fail_response (connection, |
| 2667 | "my realm", |
| 2668 | response); |
| 2669 | } |
| 2670 | else |
| 2671 | { |
| 2672 | const char *page = "<html><body>A secret.</body></html>"; |
| 2673 | response = |
| 2674 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 2675 | MHD_RESPMEM_PERSISTENT); |
| 2676 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 2677 | } |
| 2678 | MHD_destroy_response (response); |
| 2679 | return ret; |
| 2680 | } |
| 2681 | |
| 2682 | |
| 2683 | int |
| 2684 | main () |
| 2685 | { |
| 2686 | struct MHD_Daemon *daemon; |
| 2687 | |
| 2688 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 2689 | &answer_to_connection, NULL, MHD_OPTION_END); |
| 2690 | if (NULL == daemon) |
| 2691 | return 1; |
| 2692 | |
| 2693 | (void) getchar (); |
| 2694 | |
| 2695 | MHD_stop_daemon (daemon); |
| 2696 | return 0; |
| 2697 | } |
| 2698 | |
| 2699 | |
| 2700 | File: libmicrohttpd-tutorial.info, Node: simplepost.c, Next: largepost.c, Prev: basicauthentication.c, Up: Example programs |
| 2701 | |
| 2702 | C.5 simplepost.c |
| 2703 | ================ |
| 2704 | |
| 2705 | /* Feel free to use this example code in any way |
| 2706 | you see fit (Public Domain) */ |
| 2707 | |
| 2708 | #include <sys/types.h> |
| 2709 | #ifndef _WIN32 |
| 2710 | #include <sys/select.h> |
| 2711 | #include <sys/socket.h> |
| 2712 | #else |
| 2713 | #include <winsock2.h> |
| 2714 | #endif |
| 2715 | #include <microhttpd.h> |
| 2716 | #include <stdio.h> |
| 2717 | #include <string.h> |
| 2718 | #include <stdlib.h> |
| 2719 | |
| 2720 | #define PORT 8888 |
| 2721 | #define POSTBUFFERSIZE 512 |
| 2722 | #define MAXNAMESIZE 20 |
| 2723 | #define MAXANSWERSIZE 512 |
| 2724 | |
| 2725 | #define GET 0 |
| 2726 | #define POST 1 |
| 2727 | |
| 2728 | struct connection_info_struct |
| 2729 | { |
| 2730 | int connectiontype; |
| 2731 | char *answerstring; |
| 2732 | struct MHD_PostProcessor *postprocessor; |
| 2733 | }; |
| 2734 | |
| 2735 | const char *askpage = "<html><body>\ |
| 2736 | What's your name, Sir?<br>\ |
| 2737 | <form action=\"/namepost\" method=\"post\">\ |
| 2738 | <input name=\"name\" type=\"text\"\ |
| 2739 | <input type=\"submit\" value=\" Send \"></form>\ |
| 2740 | </body></html>"; |
| 2741 | |
| 2742 | const char *greetingpage = |
| 2743 | "<html><body><h1>Welcome, %s!</center></h1></body></html>"; |
| 2744 | |
| 2745 | const char *errorpage = |
| 2746 | "<html><body>This doesn't seem to be right.</body></html>"; |
| 2747 | |
| 2748 | |
| 2749 | static int |
| 2750 | send_page (struct MHD_Connection *connection, const char *page) |
| 2751 | { |
| 2752 | int ret; |
| 2753 | struct MHD_Response *response; |
| 2754 | |
| 2755 | |
| 2756 | response = |
| 2757 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 2758 | MHD_RESPMEM_PERSISTENT); |
| 2759 | if (!response) |
| 2760 | return MHD_NO; |
| 2761 | |
| 2762 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 2763 | MHD_destroy_response (response); |
| 2764 | |
| 2765 | return ret; |
| 2766 | } |
| 2767 | |
| 2768 | |
| 2769 | static int |
| 2770 | iterate_post (void *coninfo_cls, enum MHD_ValueKind kind, const char *key, |
| 2771 | const char *filename, const char *content_type, |
| 2772 | const char *transfer_encoding, const char *data, uint64_t off, |
| 2773 | size_t size) |
| 2774 | { |
| 2775 | struct connection_info_struct *con_info = coninfo_cls; |
| 2776 | |
| 2777 | if (0 == strcmp (key, "name")) |
| 2778 | { |
| 2779 | if ((size > 0) && (size <= MAXNAMESIZE)) |
| 2780 | { |
| 2781 | char *answerstring; |
| 2782 | answerstring = malloc (MAXANSWERSIZE); |
| 2783 | if (!answerstring) |
| 2784 | return MHD_NO; |
| 2785 | |
| 2786 | snprintf (answerstring, MAXANSWERSIZE, greetingpage, data); |
| 2787 | con_info->answerstring = answerstring; |
| 2788 | } |
| 2789 | else |
| 2790 | con_info->answerstring = NULL; |
| 2791 | |
| 2792 | return MHD_NO; |
| 2793 | } |
| 2794 | |
| 2795 | return MHD_YES; |
| 2796 | } |
| 2797 | |
| 2798 | static void |
| 2799 | request_completed (void *cls, struct MHD_Connection *connection, |
| 2800 | void **con_cls, enum MHD_RequestTerminationCode toe) |
| 2801 | { |
| 2802 | struct connection_info_struct *con_info = *con_cls; |
| 2803 | |
| 2804 | if (NULL == con_info) |
| 2805 | return; |
| 2806 | |
| 2807 | if (con_info->connectiontype == POST) |
| 2808 | { |
| 2809 | MHD_destroy_post_processor (con_info->postprocessor); |
| 2810 | if (con_info->answerstring) |
| 2811 | free (con_info->answerstring); |
| 2812 | } |
| 2813 | |
| 2814 | free (con_info); |
| 2815 | *con_cls = NULL; |
| 2816 | } |
| 2817 | |
| 2818 | |
| 2819 | static int |
| 2820 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 2821 | const char *url, const char *method, |
| 2822 | const char *version, const char *upload_data, |
| 2823 | size_t *upload_data_size, void **con_cls) |
| 2824 | { |
| 2825 | if (NULL == *con_cls) |
| 2826 | { |
| 2827 | struct connection_info_struct *con_info; |
| 2828 | |
| 2829 | con_info = malloc (sizeof (struct connection_info_struct)); |
| 2830 | if (NULL == con_info) |
| 2831 | return MHD_NO; |
| 2832 | con_info->answerstring = NULL; |
| 2833 | |
| 2834 | if (0 == strcmp (method, "POST")) |
| 2835 | { |
| 2836 | con_info->postprocessor = |
| 2837 | MHD_create_post_processor (connection, POSTBUFFERSIZE, |
| 2838 | iterate_post, (void *) con_info); |
| 2839 | |
| 2840 | if (NULL == con_info->postprocessor) |
| 2841 | { |
| 2842 | free (con_info); |
| 2843 | return MHD_NO; |
| 2844 | } |
| 2845 | |
| 2846 | con_info->connectiontype = POST; |
| 2847 | } |
| 2848 | else |
| 2849 | con_info->connectiontype = GET; |
| 2850 | |
| 2851 | *con_cls = (void *) con_info; |
| 2852 | |
| 2853 | return MHD_YES; |
| 2854 | } |
| 2855 | |
| 2856 | if (0 == strcmp (method, "GET")) |
| 2857 | { |
| 2858 | return send_page (connection, askpage); |
| 2859 | } |
| 2860 | |
| 2861 | if (0 == strcmp (method, "POST")) |
| 2862 | { |
| 2863 | struct connection_info_struct *con_info = *con_cls; |
| 2864 | |
| 2865 | if (*upload_data_size != 0) |
| 2866 | { |
| 2867 | MHD_post_process (con_info->postprocessor, upload_data, |
| 2868 | *upload_data_size); |
| 2869 | *upload_data_size = 0; |
| 2870 | |
| 2871 | return MHD_YES; |
| 2872 | } |
| 2873 | else if (NULL != con_info->answerstring) |
| 2874 | return send_page (connection, con_info->answerstring); |
| 2875 | } |
| 2876 | |
| 2877 | return send_page (connection, errorpage); |
| 2878 | } |
| 2879 | |
| 2880 | int |
| 2881 | main () |
| 2882 | { |
| 2883 | struct MHD_Daemon *daemon; |
| 2884 | |
| 2885 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 2886 | &answer_to_connection, NULL, |
| 2887 | MHD_OPTION_NOTIFY_COMPLETED, request_completed, |
| 2888 | NULL, MHD_OPTION_END); |
| 2889 | if (NULL == daemon) |
| 2890 | return 1; |
| 2891 | |
| 2892 | (void) getchar (); |
| 2893 | |
| 2894 | MHD_stop_daemon (daemon); |
| 2895 | |
| 2896 | return 0; |
| 2897 | } |
| 2898 | |
| 2899 | |
| 2900 | File: libmicrohttpd-tutorial.info, Node: largepost.c, Next: sessions.c, Prev: simplepost.c, Up: Example programs |
| 2901 | |
| 2902 | C.6 largepost.c |
| 2903 | =============== |
| 2904 | |
| 2905 | /* Feel free to use this example code in any way |
| 2906 | you see fit (Public Domain) */ |
| 2907 | |
| 2908 | #include <sys/types.h> |
| 2909 | #ifndef _WIN32 |
| 2910 | #include <sys/select.h> |
| 2911 | #include <sys/socket.h> |
| 2912 | #else |
| 2913 | #include <winsock2.h> |
| 2914 | #endif |
| 2915 | #include <stdio.h> |
| 2916 | #include <stdlib.h> |
| 2917 | #include <string.h> |
| 2918 | #include <microhttpd.h> |
| 2919 | |
| 2920 | #define PORT 8888 |
| 2921 | #define POSTBUFFERSIZE 512 |
| 2922 | #define MAXCLIENTS 2 |
| 2923 | |
| 2924 | #define GET 0 |
| 2925 | #define POST 1 |
| 2926 | |
| 2927 | static unsigned int nr_of_uploading_clients = 0; |
| 2928 | |
| 2929 | struct connection_info_struct |
| 2930 | { |
| 2931 | int connectiontype; |
| 2932 | struct MHD_PostProcessor *postprocessor; |
| 2933 | FILE *fp; |
| 2934 | const char *answerstring; |
| 2935 | int answercode; |
| 2936 | }; |
| 2937 | |
| 2938 | const char *askpage = "<html><body>\n\ |
| 2939 | Upload a file, please!<br>\n\ |
| 2940 | There are %u clients uploading at the moment.<br>\n\ |
| 2941 | <form action=\"/filepost\" method=\"post\" enctype=\"multipart/form-data\">\n\ |
| 2942 | <input name=\"file\" type=\"file\">\n\ |
| 2943 | <input type=\"submit\" value=\" Send \"></form>\n\ |
| 2944 | </body></html>"; |
| 2945 | |
| 2946 | const char *busypage = |
| 2947 | "<html><body>This server is busy, please try again later.</body></html>"; |
| 2948 | |
| 2949 | const char *completepage = |
| 2950 | "<html><body>The upload has been completed.</body></html>"; |
| 2951 | |
| 2952 | const char *errorpage = |
| 2953 | "<html><body>This doesn't seem to be right.</body></html>"; |
| 2954 | const char *servererrorpage = |
| 2955 | "<html><body>An internal server error has occured.</body></html>"; |
| 2956 | const char *fileexistspage = |
| 2957 | "<html><body>This file already exists.</body></html>"; |
| 2958 | |
| 2959 | |
| 2960 | static int |
| 2961 | send_page (struct MHD_Connection *connection, const char *page, |
| 2962 | int status_code) |
| 2963 | { |
| 2964 | int ret; |
| 2965 | struct MHD_Response *response; |
| 2966 | |
| 2967 | response = |
| 2968 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 2969 | MHD_RESPMEM_MUST_COPY); |
| 2970 | if (!response) |
| 2971 | return MHD_NO; |
| 2972 | MHD_add_response_header (response, MHD_HTTP_HEADER_CONTENT_TYPE, "text/html"); |
| 2973 | ret = MHD_queue_response (connection, status_code, response); |
| 2974 | MHD_destroy_response (response); |
| 2975 | |
| 2976 | return ret; |
| 2977 | } |
| 2978 | |
| 2979 | |
| 2980 | static int |
| 2981 | iterate_post (void *coninfo_cls, enum MHD_ValueKind kind, const char *key, |
| 2982 | const char *filename, const char *content_type, |
| 2983 | const char *transfer_encoding, const char *data, uint64_t off, |
| 2984 | size_t size) |
| 2985 | { |
| 2986 | struct connection_info_struct *con_info = coninfo_cls; |
| 2987 | FILE *fp; |
| 2988 | |
| 2989 | con_info->answerstring = servererrorpage; |
| 2990 | con_info->answercode = MHD_HTTP_INTERNAL_SERVER_ERROR; |
| 2991 | |
| 2992 | if (0 != strcmp (key, "file")) |
| 2993 | return MHD_NO; |
| 2994 | |
| 2995 | if (!con_info->fp) |
| 2996 | { |
| 2997 | if (NULL != (fp = fopen (filename, "rb"))) |
| 2998 | { |
| 2999 | fclose (fp); |
| 3000 | con_info->answerstring = fileexistspage; |
| 3001 | con_info->answercode = MHD_HTTP_FORBIDDEN; |
| 3002 | return MHD_NO; |
| 3003 | } |
| 3004 | |
| 3005 | con_info->fp = fopen (filename, "ab"); |
| 3006 | if (!con_info->fp) |
| 3007 | return MHD_NO; |
| 3008 | } |
| 3009 | |
| 3010 | if (size > 0) |
| 3011 | { |
| 3012 | if (!fwrite (data, size, sizeof (char), con_info->fp)) |
| 3013 | return MHD_NO; |
| 3014 | } |
| 3015 | |
| 3016 | con_info->answerstring = completepage; |
| 3017 | con_info->answercode = MHD_HTTP_OK; |
| 3018 | |
| 3019 | return MHD_YES; |
| 3020 | } |
| 3021 | |
| 3022 | |
| 3023 | static void |
| 3024 | request_completed (void *cls, struct MHD_Connection *connection, |
| 3025 | void **con_cls, enum MHD_RequestTerminationCode toe) |
| 3026 | { |
| 3027 | struct connection_info_struct *con_info = *con_cls; |
| 3028 | |
| 3029 | if (NULL == con_info) |
| 3030 | return; |
| 3031 | |
| 3032 | if (con_info->connectiontype == POST) |
| 3033 | { |
| 3034 | if (NULL != con_info->postprocessor) |
| 3035 | { |
| 3036 | MHD_destroy_post_processor (con_info->postprocessor); |
| 3037 | nr_of_uploading_clients--; |
| 3038 | } |
| 3039 | |
| 3040 | if (con_info->fp) |
| 3041 | fclose (con_info->fp); |
| 3042 | } |
| 3043 | |
| 3044 | free (con_info); |
| 3045 | *con_cls = NULL; |
| 3046 | } |
| 3047 | |
| 3048 | |
| 3049 | static int |
| 3050 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 3051 | const char *url, const char *method, |
| 3052 | const char *version, const char *upload_data, |
| 3053 | size_t *upload_data_size, void **con_cls) |
| 3054 | { |
| 3055 | if (NULL == *con_cls) |
| 3056 | { |
| 3057 | struct connection_info_struct *con_info; |
| 3058 | |
| 3059 | if (nr_of_uploading_clients >= MAXCLIENTS) |
| 3060 | return send_page (connection, busypage, MHD_HTTP_SERVICE_UNAVAILABLE); |
| 3061 | |
| 3062 | con_info = malloc (sizeof (struct connection_info_struct)); |
| 3063 | if (NULL == con_info) |
| 3064 | return MHD_NO; |
| 3065 | |
| 3066 | con_info->fp = NULL; |
| 3067 | |
| 3068 | if (0 == strcmp (method, "POST")) |
| 3069 | { |
| 3070 | con_info->postprocessor = |
| 3071 | MHD_create_post_processor (connection, POSTBUFFERSIZE, |
| 3072 | iterate_post, (void *) con_info); |
| 3073 | |
| 3074 | if (NULL == con_info->postprocessor) |
| 3075 | { |
| 3076 | free (con_info); |
| 3077 | return MHD_NO; |
| 3078 | } |
| 3079 | |
| 3080 | nr_of_uploading_clients++; |
| 3081 | |
| 3082 | con_info->connectiontype = POST; |
| 3083 | con_info->answercode = MHD_HTTP_OK; |
| 3084 | con_info->answerstring = completepage; |
| 3085 | } |
| 3086 | else |
| 3087 | con_info->connectiontype = GET; |
| 3088 | |
| 3089 | *con_cls = (void *) con_info; |
| 3090 | |
| 3091 | return MHD_YES; |
| 3092 | } |
| 3093 | |
| 3094 | if (0 == strcmp (method, "GET")) |
| 3095 | { |
| 3096 | char buffer[1024]; |
| 3097 | |
| 3098 | snprintf (buffer, sizeof (buffer), askpage, nr_of_uploading_clients); |
| 3099 | return send_page (connection, buffer, MHD_HTTP_OK); |
| 3100 | } |
| 3101 | |
| 3102 | if (0 == strcmp (method, "POST")) |
| 3103 | { |
| 3104 | struct connection_info_struct *con_info = *con_cls; |
| 3105 | |
| 3106 | if (0 != *upload_data_size) |
| 3107 | { |
| 3108 | MHD_post_process (con_info->postprocessor, upload_data, |
| 3109 | *upload_data_size); |
| 3110 | *upload_data_size = 0; |
| 3111 | |
| 3112 | return MHD_YES; |
| 3113 | } |
| 3114 | else |
| 3115 | { |
| 3116 | if (NULL != con_info->fp) |
| 3117 | { |
| 3118 | fclose (con_info->fp); |
| 3119 | con_info->fp = NULL; |
| 3120 | } |
| 3121 | /* Now it is safe to open and inspect the file before calling send_page with a response */ |
| 3122 | return send_page (connection, con_info->answerstring, |
| 3123 | con_info->answercode); |
| 3124 | } |
| 3125 | |
| 3126 | } |
| 3127 | |
| 3128 | return send_page (connection, errorpage, MHD_HTTP_BAD_REQUEST); |
| 3129 | } |
| 3130 | |
| 3131 | |
| 3132 | int |
| 3133 | main () |
| 3134 | { |
| 3135 | struct MHD_Daemon *daemon; |
| 3136 | |
| 3137 | daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY, PORT, NULL, NULL, |
| 3138 | &answer_to_connection, NULL, |
| 3139 | MHD_OPTION_NOTIFY_COMPLETED, request_completed, |
| 3140 | NULL, MHD_OPTION_END); |
| 3141 | if (NULL == daemon) |
| 3142 | return 1; |
| 3143 | (void) getchar (); |
| 3144 | MHD_stop_daemon (daemon); |
| 3145 | return 0; |
| 3146 | } |
| 3147 | |
| 3148 | |
| 3149 | File: libmicrohttpd-tutorial.info, Node: sessions.c, Next: tlsauthentication.c, Prev: largepost.c, Up: Example programs |
| 3150 | |
| 3151 | C.7 sessions.c |
| 3152 | ============== |
| 3153 | |
| 3154 | /* Feel free to use this example code in any way |
| 3155 | you see fit (Public Domain) */ |
| 3156 | |
| 3157 | /* needed for asprintf */ |
| 3158 | #define _GNU_SOURCE |
| 3159 | |
| 3160 | #include <stdlib.h> |
| 3161 | #include <string.h> |
| 3162 | #include <stdio.h> |
| 3163 | #include <errno.h> |
| 3164 | #include <time.h> |
| 3165 | #include <microhttpd.h> |
| 3166 | |
| 3167 | #if defined _WIN32 && !defined(__MINGW64_VERSION_MAJOR) |
| 3168 | static int |
| 3169 | asprintf (char **resultp, const char *format, ...) |
| 3170 | { |
| 3171 | va_list argptr; |
| 3172 | char *result = NULL; |
| 3173 | int len = 0; |
| 3174 | |
| 3175 | if (format == NULL) |
| 3176 | return -1; |
| 3177 | |
| 3178 | va_start (argptr, format); |
| 3179 | |
| 3180 | len = _vscprintf ((char *) format, argptr); |
| 3181 | if (len >= 0) |
| 3182 | { |
| 3183 | len += 1; |
| 3184 | result = (char *) malloc (sizeof (char *) * len); |
| 3185 | if (result != NULL) |
| 3186 | { |
| 3187 | int len2 = _vscprintf ((char *) format, argptr); |
| 3188 | if (len2 != len - 1 || len2 <= 0) |
| 3189 | { |
| 3190 | free (result); |
| 3191 | result = NULL; |
| 3192 | len = -1; |
| 3193 | } |
| 3194 | else |
| 3195 | { |
| 3196 | len = len2; |
| 3197 | if (resultp) |
| 3198 | *resultp = result; |
| 3199 | } |
| 3200 | } |
| 3201 | } |
| 3202 | va_end (argptr); |
| 3203 | return len; |
| 3204 | } |
| 3205 | #endif |
| 3206 | |
| 3207 | /** |
| 3208 | * Invalid method page. |
| 3209 | */ |
| 3210 | #define METHOD_ERROR "<html><head><title>Illegal request</title></head><body>Go away.</body></html>" |
| 3211 | |
| 3212 | /** |
| 3213 | * Invalid URL page. |
| 3214 | */ |
| 3215 | #define NOT_FOUND_ERROR "<html><head><title>Not found</title></head><body>Go away.</body></html>" |
| 3216 | |
| 3217 | /** |
| 3218 | * Front page. (/) |
| 3219 | */ |
| 3220 | #define MAIN_PAGE "<html><head><title>Welcome</title></head><body><form action=\"/2\" method=\"post\">What is your name? <input type=\"text\" name=\"v1\" value=\"%s\" /><input type=\"submit\" value=\"Next\" /></body></html>" |
| 3221 | |
| 3222 | /** |
| 3223 | * Second page. (/2) |
| 3224 | */ |
| 3225 | #define SECOND_PAGE "<html><head><title>Tell me more</title></head><body><a href=\"/\">previous</a> <form action=\"/S\" method=\"post\">%s, what is your job? <input type=\"text\" name=\"v2\" value=\"%s\" /><input type=\"submit\" value=\"Next\" /></body></html>" |
| 3226 | |
| 3227 | /** |
| 3228 | * Second page (/S) |
| 3229 | */ |
| 3230 | #define SUBMIT_PAGE "<html><head><title>Ready to submit?</title></head><body><form action=\"/F\" method=\"post\"><a href=\"/2\">previous </a> <input type=\"hidden\" name=\"DONE\" value=\"yes\" /><input type=\"submit\" value=\"Submit\" /></body></html>" |
| 3231 | |
| 3232 | /** |
| 3233 | * Last page. |
| 3234 | */ |
| 3235 | #define LAST_PAGE "<html><head><title>Thank you</title></head><body>Thank you.</body></html>" |
| 3236 | |
| 3237 | /** |
| 3238 | * Name of our cookie. |
| 3239 | */ |
| 3240 | #define COOKIE_NAME "session" |
| 3241 | |
| 3242 | |
| 3243 | /** |
| 3244 | * State we keep for each user/session/browser. |
| 3245 | */ |
| 3246 | struct Session |
| 3247 | { |
| 3248 | /** |
| 3249 | * We keep all sessions in a linked list. |
| 3250 | */ |
| 3251 | struct Session *next; |
| 3252 | |
| 3253 | /** |
| 3254 | * Unique ID for this session. |
| 3255 | */ |
| 3256 | char sid[33]; |
| 3257 | |
| 3258 | /** |
| 3259 | * Reference counter giving the number of connections |
| 3260 | * currently using this session. |
| 3261 | */ |
| 3262 | unsigned int rc; |
| 3263 | |
| 3264 | /** |
| 3265 | * Time when this session was last active. |
| 3266 | */ |
| 3267 | time_t start; |
| 3268 | |
| 3269 | /** |
| 3270 | * String submitted via form. |
| 3271 | */ |
| 3272 | char value_1[64]; |
| 3273 | |
| 3274 | /** |
| 3275 | * Another value submitted via form. |
| 3276 | */ |
| 3277 | char value_2[64]; |
| 3278 | |
| 3279 | }; |
| 3280 | |
| 3281 | |
| 3282 | /** |
| 3283 | * Data kept per request. |
| 3284 | */ |
| 3285 | struct Request |
| 3286 | { |
| 3287 | |
| 3288 | /** |
| 3289 | * Associated session. |
| 3290 | */ |
| 3291 | struct Session *session; |
| 3292 | |
| 3293 | /** |
| 3294 | * Post processor handling form data (IF this is |
| 3295 | * a POST request). |
| 3296 | */ |
| 3297 | struct MHD_PostProcessor *pp; |
| 3298 | |
| 3299 | /** |
| 3300 | * URL to serve in response to this POST (if this request |
| 3301 | * was a 'POST') |
| 3302 | */ |
| 3303 | const char *post_url; |
| 3304 | |
| 3305 | }; |
| 3306 | |
| 3307 | |
| 3308 | /** |
| 3309 | * Linked list of all active sessions. Yes, O(n) but a |
| 3310 | * hash table would be overkill for a simple example... |
| 3311 | */ |
| 3312 | static struct Session *sessions; |
| 3313 | |
| 3314 | |
| 3315 | |
| 3316 | |
| 3317 | /** |
| 3318 | * Return the session handle for this connection, or |
| 3319 | * create one if this is a new user. |
| 3320 | */ |
| 3321 | static struct Session * |
| 3322 | get_session (struct MHD_Connection *connection) |
| 3323 | { |
| 3324 | struct Session *ret; |
| 3325 | const char *cookie; |
| 3326 | |
| 3327 | cookie = MHD_lookup_connection_value (connection, |
| 3328 | MHD_COOKIE_KIND, |
| 3329 | COOKIE_NAME); |
| 3330 | if (cookie != NULL) |
| 3331 | { |
| 3332 | /* find existing session */ |
| 3333 | ret = sessions; |
| 3334 | while (NULL != ret) |
| 3335 | { |
| 3336 | if (0 == strcmp (cookie, ret->sid)) |
| 3337 | break; |
| 3338 | ret = ret->next; |
| 3339 | } |
| 3340 | if (NULL != ret) |
| 3341 | { |
| 3342 | ret->rc++; |
| 3343 | return ret; |
| 3344 | } |
| 3345 | } |
| 3346 | /* create fresh session */ |
| 3347 | ret = calloc (1, sizeof (struct Session)); |
| 3348 | if (NULL == ret) |
| 3349 | { |
| 3350 | fprintf (stderr, "calloc error: %s\n", strerror (errno)); |
| 3351 | return NULL; |
| 3352 | } |
| 3353 | /* not a super-secure way to generate a random session ID, |
| 3354 | but should do for a simple example... */ |
| 3355 | snprintf (ret->sid, |
| 3356 | sizeof (ret->sid), |
| 3357 | "%X%X%X%X", |
| 3358 | (unsigned int) rand (), |
| 3359 | (unsigned int) rand (), |
| 3360 | (unsigned int) rand (), |
| 3361 | (unsigned int) rand ()); |
| 3362 | ret->rc++; |
| 3363 | ret->start = time (NULL); |
| 3364 | ret->next = sessions; |
| 3365 | sessions = ret; |
| 3366 | return ret; |
| 3367 | } |
| 3368 | |
| 3369 | |
| 3370 | /** |
| 3371 | * Type of handler that generates a reply. |
| 3372 | * |
| 3373 | * @param cls content for the page (handler-specific) |
| 3374 | * @param mime mime type to use |
| 3375 | * @param session session information |
| 3376 | * @param connection connection to process |
| 3377 | * @param MHD_YES on success, MHD_NO on failure |
| 3378 | */ |
| 3379 | typedef int (*PageHandler)(const void *cls, |
| 3380 | const char *mime, |
| 3381 | struct Session *session, |
| 3382 | struct MHD_Connection *connection); |
| 3383 | |
| 3384 | |
| 3385 | /** |
| 3386 | * Entry we generate for each page served. |
| 3387 | */ |
| 3388 | struct Page |
| 3389 | { |
| 3390 | /** |
| 3391 | * Acceptable URL for this page. |
| 3392 | */ |
| 3393 | const char *url; |
| 3394 | |
| 3395 | /** |
| 3396 | * Mime type to set for the page. |
| 3397 | */ |
| 3398 | const char *mime; |
| 3399 | |
| 3400 | /** |
| 3401 | * Handler to call to generate response. |
| 3402 | */ |
| 3403 | PageHandler handler; |
| 3404 | |
| 3405 | /** |
| 3406 | * Extra argument to handler. |
| 3407 | */ |
| 3408 | const void *handler_cls; |
| 3409 | }; |
| 3410 | |
| 3411 | |
| 3412 | /** |
| 3413 | * Add header to response to set a session cookie. |
| 3414 | * |
| 3415 | * @param session session to use |
| 3416 | * @param response response to modify |
| 3417 | */ |
| 3418 | static void |
| 3419 | add_session_cookie (struct Session *session, |
| 3420 | struct MHD_Response *response) |
| 3421 | { |
| 3422 | char cstr[256]; |
| 3423 | snprintf (cstr, |
| 3424 | sizeof (cstr), |
| 3425 | "%s=%s", |
| 3426 | COOKIE_NAME, |
| 3427 | session->sid); |
| 3428 | if (MHD_NO == |
| 3429 | MHD_add_response_header (response, |
| 3430 | MHD_HTTP_HEADER_SET_COOKIE, |
| 3431 | cstr)) |
| 3432 | { |
| 3433 | fprintf (stderr, |
| 3434 | "Failed to set session cookie header!\n"); |
| 3435 | } |
| 3436 | } |
| 3437 | |
| 3438 | |
| 3439 | /** |
| 3440 | * Handler that returns a simple static HTTP page that |
| 3441 | * is passed in via 'cls'. |
| 3442 | * |
| 3443 | * @param cls a 'const char *' with the HTML webpage to return |
| 3444 | * @param mime mime type to use |
| 3445 | * @param session session handle |
| 3446 | * @param connection connection to use |
| 3447 | */ |
| 3448 | static int |
| 3449 | serve_simple_form (const void *cls, |
| 3450 | const char *mime, |
| 3451 | struct Session *session, |
| 3452 | struct MHD_Connection *connection) |
| 3453 | { |
| 3454 | int ret; |
| 3455 | const char *form = cls; |
| 3456 | struct MHD_Response *response; |
| 3457 | |
| 3458 | /* return static form */ |
| 3459 | response = MHD_create_response_from_buffer (strlen (form), |
| 3460 | (void *) form, |
| 3461 | MHD_RESPMEM_PERSISTENT); |
| 3462 | add_session_cookie (session, response); |
| 3463 | MHD_add_response_header (response, |
| 3464 | MHD_HTTP_HEADER_CONTENT_ENCODING, |
| 3465 | mime); |
| 3466 | ret = MHD_queue_response (connection, |
| 3467 | MHD_HTTP_OK, |
| 3468 | response); |
| 3469 | MHD_destroy_response (response); |
| 3470 | return ret; |
| 3471 | } |
| 3472 | |
| 3473 | |
| 3474 | /** |
| 3475 | * Handler that adds the 'v1' value to the given HTML code. |
| 3476 | * |
| 3477 | * @param cls a 'const char *' with the HTML webpage to return |
| 3478 | * @param mime mime type to use |
| 3479 | * @param session session handle |
| 3480 | * @param connection connection to use |
| 3481 | */ |
| 3482 | static int |
| 3483 | fill_v1_form (const void *cls, |
| 3484 | const char *mime, |
| 3485 | struct Session *session, |
| 3486 | struct MHD_Connection *connection) |
| 3487 | { |
| 3488 | int ret; |
| 3489 | const char *form = cls; |
| 3490 | char *reply; |
| 3491 | struct MHD_Response *response; |
| 3492 | |
| 3493 | if (-1 == asprintf (&reply, |
| 3494 | form, |
| 3495 | session->value_1)) |
| 3496 | { |
| 3497 | /* oops */ |
| 3498 | return MHD_NO; |
| 3499 | } |
| 3500 | /* return static form */ |
| 3501 | response = MHD_create_response_from_buffer (strlen (reply), |
| 3502 | (void *) reply, |
| 3503 | MHD_RESPMEM_MUST_FREE); |
| 3504 | add_session_cookie (session, response); |
| 3505 | MHD_add_response_header (response, |
| 3506 | MHD_HTTP_HEADER_CONTENT_ENCODING, |
| 3507 | mime); |
| 3508 | ret = MHD_queue_response (connection, |
| 3509 | MHD_HTTP_OK, |
| 3510 | response); |
| 3511 | MHD_destroy_response (response); |
| 3512 | return ret; |
| 3513 | } |
| 3514 | |
| 3515 | |
| 3516 | /** |
| 3517 | * Handler that adds the 'v1' and 'v2' values to the given HTML code. |
| 3518 | * |
| 3519 | * @param cls a 'const char *' with the HTML webpage to return |
| 3520 | * @param mime mime type to use |
| 3521 | * @param session session handle |
| 3522 | * @param connection connection to use |
| 3523 | */ |
| 3524 | static int |
| 3525 | fill_v1_v2_form (const void *cls, |
| 3526 | const char *mime, |
| 3527 | struct Session *session, |
| 3528 | struct MHD_Connection *connection) |
| 3529 | { |
| 3530 | int ret; |
| 3531 | const char *form = cls; |
| 3532 | char *reply; |
| 3533 | struct MHD_Response *response; |
| 3534 | |
| 3535 | if (-1 == asprintf (&reply, |
| 3536 | form, |
| 3537 | session->value_1, |
| 3538 | session->value_2)) |
| 3539 | { |
| 3540 | /* oops */ |
| 3541 | return MHD_NO; |
| 3542 | } |
| 3543 | /* return static form */ |
| 3544 | response = MHD_create_response_from_buffer (strlen (reply), |
| 3545 | (void *) reply, |
| 3546 | MHD_RESPMEM_MUST_FREE); |
| 3547 | add_session_cookie (session, response); |
| 3548 | MHD_add_response_header (response, |
| 3549 | MHD_HTTP_HEADER_CONTENT_ENCODING, |
| 3550 | mime); |
| 3551 | ret = MHD_queue_response (connection, |
| 3552 | MHD_HTTP_OK, |
| 3553 | response); |
| 3554 | MHD_destroy_response (response); |
| 3555 | return ret; |
| 3556 | } |
| 3557 | |
| 3558 | |
| 3559 | /** |
| 3560 | * Handler used to generate a 404 reply. |
| 3561 | * |
| 3562 | * @param cls a 'const char *' with the HTML webpage to return |
| 3563 | * @param mime mime type to use |
| 3564 | * @param session session handle |
| 3565 | * @param connection connection to use |
| 3566 | */ |
| 3567 | static int |
| 3568 | not_found_page (const void *cls, |
| 3569 | const char *mime, |
| 3570 | struct Session *session, |
| 3571 | struct MHD_Connection *connection) |
| 3572 | { |
| 3573 | int ret; |
| 3574 | struct MHD_Response *response; |
| 3575 | |
| 3576 | /* unsupported HTTP method */ |
| 3577 | response = MHD_create_response_from_buffer (strlen (NOT_FOUND_ERROR), |
| 3578 | (void *) NOT_FOUND_ERROR, |
| 3579 | MHD_RESPMEM_PERSISTENT); |
| 3580 | ret = MHD_queue_response (connection, |
| 3581 | MHD_HTTP_NOT_FOUND, |
| 3582 | response); |
| 3583 | MHD_add_response_header (response, |
| 3584 | MHD_HTTP_HEADER_CONTENT_ENCODING, |
| 3585 | mime); |
| 3586 | MHD_destroy_response (response); |
| 3587 | return ret; |
| 3588 | } |
| 3589 | |
| 3590 | |
| 3591 | /** |
| 3592 | * List of all pages served by this HTTP server. |
| 3593 | */ |
| 3594 | static struct Page pages[] = |
| 3595 | { |
| 3596 | { "/", "text/html", &fill_v1_form, MAIN_PAGE }, |
| 3597 | { "/2", "text/html", &fill_v1_v2_form, SECOND_PAGE }, |
| 3598 | { "/S", "text/html", &serve_simple_form, SUBMIT_PAGE }, |
| 3599 | { "/F", "text/html", &serve_simple_form, LAST_PAGE }, |
| 3600 | { NULL, NULL, ¬_found_page, NULL } /* 404 */ |
| 3601 | }; |
| 3602 | |
| 3603 | |
| 3604 | |
| 3605 | /** |
| 3606 | * Iterator over key-value pairs where the value |
| 3607 | * maybe made available in increments and/or may |
| 3608 | * not be zero-terminated. Used for processing |
| 3609 | * POST data. |
| 3610 | * |
| 3611 | * @param cls user-specified closure |
| 3612 | * @param kind type of the value |
| 3613 | * @param key 0-terminated key for the value |
| 3614 | * @param filename name of the uploaded file, NULL if not known |
| 3615 | * @param content_type mime-type of the data, NULL if not known |
| 3616 | * @param transfer_encoding encoding of the data, NULL if not known |
| 3617 | * @param data pointer to size bytes of data at the |
| 3618 | * specified offset |
| 3619 | * @param off offset of data in the overall value |
| 3620 | * @param size number of bytes in data available |
| 3621 | * @return MHD_YES to continue iterating, |
| 3622 | * MHD_NO to abort the iteration |
| 3623 | */ |
| 3624 | static int |
| 3625 | post_iterator (void *cls, |
| 3626 | enum MHD_ValueKind kind, |
| 3627 | const char *key, |
| 3628 | const char *filename, |
| 3629 | const char *content_type, |
| 3630 | const char *transfer_encoding, |
| 3631 | const char *data, uint64_t off, size_t size) |
| 3632 | { |
| 3633 | struct Request *request = cls; |
| 3634 | struct Session *session = request->session; |
| 3635 | |
| 3636 | if (0 == strcmp ("DONE", key)) |
| 3637 | { |
| 3638 | fprintf (stdout, |
| 3639 | "Session `%s' submitted `%s', `%s'\n", |
| 3640 | session->sid, |
| 3641 | session->value_1, |
| 3642 | session->value_2); |
| 3643 | return MHD_YES; |
| 3644 | } |
| 3645 | if (0 == strcmp ("v1", key)) |
| 3646 | { |
| 3647 | if (size + off > sizeof(session->value_1)) |
| 3648 | size = sizeof (session->value_1) - off; |
| 3649 | memcpy (&session->value_1[off], |
| 3650 | data, |
| 3651 | size); |
| 3652 | if (size + off < sizeof (session->value_1)) |
| 3653 | session->value_1[size+off] = '\0'; |
| 3654 | return MHD_YES; |
| 3655 | } |
| 3656 | if (0 == strcmp ("v2", key)) |
| 3657 | { |
| 3658 | if (size + off > sizeof(session->value_2)) |
| 3659 | size = sizeof (session->value_2) - off; |
| 3660 | memcpy (&session->value_2[off], |
| 3661 | data, |
| 3662 | size); |
| 3663 | if (size + off < sizeof (session->value_2)) |
| 3664 | session->value_2[size+off] = '\0'; |
| 3665 | return MHD_YES; |
| 3666 | } |
| 3667 | fprintf (stderr, "Unsupported form value `%s'\n", key); |
| 3668 | return MHD_YES; |
| 3669 | } |
| 3670 | |
| 3671 | |
| 3672 | /** |
| 3673 | * Main MHD callback for handling requests. |
| 3674 | * |
| 3675 | * |
| 3676 | * @param cls argument given together with the function |
| 3677 | * pointer when the handler was registered with MHD |
| 3678 | * @param connection handle to connection which is being processed |
| 3679 | * @param url the requested url |
| 3680 | * @param method the HTTP method used ("GET", "PUT", etc.) |
| 3681 | * @param version the HTTP version string (i.e. "HTTP/1.1") |
| 3682 | * @param upload_data the data being uploaded (excluding HEADERS, |
| 3683 | * for a POST that fits into memory and that is encoded |
| 3684 | * with a supported encoding, the POST data will NOT be |
| 3685 | * given in upload_data and is instead available as |
| 3686 | * part of MHD_get_connection_values; very large POST |
| 3687 | * data *will* be made available incrementally in |
| 3688 | * upload_data) |
| 3689 | * @param upload_data_size set initially to the size of the |
| 3690 | * upload_data provided; the method must update this |
| 3691 | * value to the number of bytes NOT processed; |
| 3692 | * @param ptr pointer that the callback can set to some |
| 3693 | * address and that will be preserved by MHD for future |
| 3694 | * calls for this request; since the access handler may |
| 3695 | * be called many times (i.e., for a PUT/POST operation |
| 3696 | * with plenty of upload data) this allows the application |
| 3697 | * to easily associate some request-specific state. |
| 3698 | * If necessary, this state can be cleaned up in the |
| 3699 | * global "MHD_RequestCompleted" callback (which |
| 3700 | * can be set with the MHD_OPTION_NOTIFY_COMPLETED). |
| 3701 | * Initially, <tt>*con_cls</tt> will be NULL. |
| 3702 | * @return MHS_YES if the connection was handled successfully, |
| 3703 | * MHS_NO if the socket must be closed due to a serios |
| 3704 | * error while handling the request |
| 3705 | */ |
| 3706 | static int |
| 3707 | create_response (void *cls, |
| 3708 | struct MHD_Connection *connection, |
| 3709 | const char *url, |
| 3710 | const char *method, |
| 3711 | const char *version, |
| 3712 | const char *upload_data, |
| 3713 | size_t *upload_data_size, |
| 3714 | void **ptr) |
| 3715 | { |
| 3716 | struct MHD_Response *response; |
| 3717 | struct Request *request; |
| 3718 | struct Session *session; |
| 3719 | int ret; |
| 3720 | unsigned int i; |
| 3721 | |
| 3722 | request = *ptr; |
| 3723 | if (NULL == request) |
| 3724 | { |
| 3725 | request = calloc (1, sizeof (struct Request)); |
| 3726 | if (NULL == request) |
| 3727 | { |
| 3728 | fprintf (stderr, "calloc error: %s\n", strerror (errno)); |
| 3729 | return MHD_NO; |
| 3730 | } |
| 3731 | *ptr = request; |
| 3732 | if (0 == strcmp (method, MHD_HTTP_METHOD_POST)) |
| 3733 | { |
| 3734 | request->pp = MHD_create_post_processor (connection, 1024, |
| 3735 | &post_iterator, request); |
| 3736 | if (NULL == request->pp) |
| 3737 | { |
| 3738 | fprintf (stderr, "Failed to setup post processor for `%s'\n", |
| 3739 | url); |
| 3740 | return MHD_NO; /* internal error */ |
| 3741 | } |
| 3742 | } |
| 3743 | return MHD_YES; |
| 3744 | } |
| 3745 | if (NULL == request->session) |
| 3746 | { |
| 3747 | request->session = get_session (connection); |
| 3748 | if (NULL == request->session) |
| 3749 | { |
| 3750 | fprintf (stderr, "Failed to setup session for `%s'\n", |
| 3751 | url); |
| 3752 | return MHD_NO; /* internal error */ |
| 3753 | } |
| 3754 | } |
| 3755 | session = request->session; |
| 3756 | session->start = time (NULL); |
| 3757 | if (0 == strcmp (method, MHD_HTTP_METHOD_POST)) |
| 3758 | { |
| 3759 | /* evaluate POST data */ |
| 3760 | MHD_post_process (request->pp, |
| 3761 | upload_data, |
| 3762 | *upload_data_size); |
| 3763 | if (0 != *upload_data_size) |
| 3764 | { |
| 3765 | *upload_data_size = 0; |
| 3766 | return MHD_YES; |
| 3767 | } |
| 3768 | /* done with POST data, serve response */ |
| 3769 | MHD_destroy_post_processor (request->pp); |
| 3770 | request->pp = NULL; |
| 3771 | method = MHD_HTTP_METHOD_GET; /* fake 'GET' */ |
| 3772 | if (NULL != request->post_url) |
| 3773 | url = request->post_url; |
| 3774 | } |
| 3775 | |
| 3776 | if ( (0 == strcmp (method, MHD_HTTP_METHOD_GET)) || |
| 3777 | (0 == strcmp (method, MHD_HTTP_METHOD_HEAD)) ) |
| 3778 | { |
| 3779 | /* find out which page to serve */ |
| 3780 | i=0; |
| 3781 | while ( (pages[i].url != NULL) && |
| 3782 | (0 != strcmp (pages[i].url, url)) ) |
| 3783 | i++; |
| 3784 | ret = pages[i].handler (pages[i].handler_cls, |
| 3785 | pages[i].mime, |
| 3786 | session, connection); |
| 3787 | if (ret != MHD_YES) |
| 3788 | fprintf (stderr, "Failed to create page for `%s'\n", |
| 3789 | url); |
| 3790 | return ret; |
| 3791 | } |
| 3792 | /* unsupported HTTP method */ |
| 3793 | response = MHD_create_response_from_buffer (strlen (METHOD_ERROR), |
| 3794 | (void *) METHOD_ERROR, |
| 3795 | MHD_RESPMEM_PERSISTENT); |
| 3796 | ret = MHD_queue_response (connection, |
| 3797 | MHD_HTTP_METHOD_NOT_ACCEPTABLE, |
| 3798 | response); |
| 3799 | MHD_destroy_response (response); |
| 3800 | return ret; |
| 3801 | } |
| 3802 | |
| 3803 | |
| 3804 | /** |
| 3805 | * Callback called upon completion of a request. |
| 3806 | * Decrements session reference counter. |
| 3807 | * |
| 3808 | * @param cls not used |
| 3809 | * @param connection connection that completed |
| 3810 | * @param con_cls session handle |
| 3811 | * @param toe status code |
| 3812 | */ |
| 3813 | static void |
| 3814 | request_completed_callback (void *cls, |
| 3815 | struct MHD_Connection *connection, |
| 3816 | void **con_cls, |
| 3817 | enum MHD_RequestTerminationCode toe) |
| 3818 | { |
| 3819 | struct Request *request = *con_cls; |
| 3820 | |
| 3821 | if (NULL == request) |
| 3822 | return; |
| 3823 | if (NULL != request->session) |
| 3824 | request->session->rc--; |
| 3825 | if (NULL != request->pp) |
| 3826 | MHD_destroy_post_processor (request->pp); |
| 3827 | free (request); |
| 3828 | } |
| 3829 | |
| 3830 | |
| 3831 | /** |
| 3832 | * Clean up handles of sessions that have been idle for |
| 3833 | * too long. |
| 3834 | */ |
| 3835 | static void |
| 3836 | expire_sessions () |
| 3837 | { |
| 3838 | struct Session *pos; |
| 3839 | struct Session *prev; |
| 3840 | struct Session *next; |
| 3841 | time_t now; |
| 3842 | |
| 3843 | now = time (NULL); |
| 3844 | prev = NULL; |
| 3845 | pos = sessions; |
| 3846 | while (NULL != pos) |
| 3847 | { |
| 3848 | next = pos->next; |
| 3849 | if (now - pos->start > 60 * 60) |
| 3850 | { |
| 3851 | /* expire sessions after 1h */ |
| 3852 | if (NULL == prev) |
| 3853 | sessions = pos->next; |
| 3854 | else |
| 3855 | prev->next = next; |
| 3856 | free (pos); |
| 3857 | } |
| 3858 | else |
| 3859 | prev = pos; |
| 3860 | pos = next; |
| 3861 | } |
| 3862 | } |
| 3863 | |
| 3864 | |
| 3865 | /** |
| 3866 | * Call with the port number as the only argument. |
| 3867 | * Never terminates (other than by signals, such as CTRL-C). |
| 3868 | */ |
| 3869 | int |
| 3870 | main (int argc, char *const *argv) |
| 3871 | { |
| 3872 | struct MHD_Daemon *d; |
| 3873 | struct timeval tv; |
| 3874 | struct timeval *tvp; |
| 3875 | fd_set rs; |
| 3876 | fd_set ws; |
| 3877 | fd_set es; |
| 3878 | int max; |
| 3879 | MHD_UNSIGNED_LONG_LONG mhd_timeout; |
| 3880 | |
| 3881 | if (argc != 2) |
| 3882 | { |
| 3883 | printf ("%s PORT\n", argv[0]); |
| 3884 | return 1; |
| 3885 | } |
| 3886 | /* initialize PRNG */ |
| 3887 | srand ((unsigned int) time (NULL)); |
| 3888 | d = MHD_start_daemon (MHD_USE_DEBUG, |
| 3889 | atoi (argv[1]), |
| 3890 | NULL, NULL, |
| 3891 | &create_response, NULL, |
| 3892 | MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int) 15, |
| 3893 | MHD_OPTION_NOTIFY_COMPLETED, &request_completed_callback, NULL, |
| 3894 | MHD_OPTION_END); |
| 3895 | if (NULL == d) |
| 3896 | return 1; |
| 3897 | while (1) |
| 3898 | { |
| 3899 | expire_sessions (); |
| 3900 | max = 0; |
| 3901 | FD_ZERO (&rs); |
| 3902 | FD_ZERO (&ws); |
| 3903 | FD_ZERO (&es); |
| 3904 | if (MHD_YES != MHD_get_fdset (d, &rs, &ws, &es, &max)) |
| 3905 | break; /* fatal internal error */ |
| 3906 | if (MHD_get_timeout (d, &mhd_timeout) == MHD_YES) |
| 3907 | { |
| 3908 | tv.tv_sec = mhd_timeout / 1000; |
| 3909 | tv.tv_usec = (mhd_timeout - (tv.tv_sec * 1000)) * 1000; |
| 3910 | tvp = &tv; |
| 3911 | } |
| 3912 | else |
| 3913 | tvp = NULL; |
| 3914 | if (-1 == select (max + 1, &rs, &ws, &es, tvp)) |
| 3915 | { |
| 3916 | if (EINTR != errno) |
| 3917 | fprintf (stderr, |
| 3918 | "Aborting due to error during select: %s\n", |
| 3919 | strerror (errno)); |
| 3920 | break; |
| 3921 | } |
| 3922 | MHD_run (d); |
| 3923 | } |
| 3924 | MHD_stop_daemon (d); |
| 3925 | return 0; |
| 3926 | } |
| 3927 | |
| 3928 | |
| 3929 | File: libmicrohttpd-tutorial.info, Node: tlsauthentication.c, Prev: sessions.c, Up: Example programs |
| 3930 | |
| 3931 | C.8 tlsauthentication.c |
| 3932 | ======================= |
| 3933 | |
| 3934 | /* Feel free to use this example code in any way |
| 3935 | you see fit (Public Domain) */ |
| 3936 | |
| 3937 | #include <sys/types.h> |
| 3938 | #ifndef _WIN32 |
| 3939 | #include <sys/select.h> |
| 3940 | #include <sys/socket.h> |
| 3941 | #else |
| 3942 | #include <winsock2.h> |
| 3943 | #endif |
| 3944 | #include <microhttpd.h> |
| 3945 | #include <string.h> |
| 3946 | #include <stdio.h> |
| 3947 | #include <stdlib.h> |
| 3948 | |
| 3949 | #define PORT 8888 |
| 3950 | |
| 3951 | #define REALM "\"Maintenance\"" |
| 3952 | #define USER "a legitimate user" |
| 3953 | #define PASSWORD "and his password" |
| 3954 | |
| 3955 | #define SERVERKEYFILE "server.key" |
| 3956 | #define SERVERCERTFILE "server.pem" |
| 3957 | |
| 3958 | |
| 3959 | static char * |
| 3960 | string_to_base64 (const char *message) |
| 3961 | { |
| 3962 | const char *lookup = |
| 3963 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 3964 | unsigned long l; |
| 3965 | int i; |
| 3966 | char *tmp; |
| 3967 | size_t length = strlen (message); |
| 3968 | |
| 3969 | tmp = malloc (length * 2); |
| 3970 | if (NULL == tmp) |
| 3971 | return tmp; |
| 3972 | |
| 3973 | tmp[0] = 0; |
| 3974 | |
| 3975 | for (i = 0; i < length; i += 3) |
| 3976 | { |
| 3977 | l = (((unsigned long) message[i]) << 16) |
| 3978 | | (((i + 1) < length) ? (((unsigned long) message[i + 1]) << 8) : 0) |
| 3979 | | (((i + 2) < length) ? ((unsigned long) message[i + 2]) : 0); |
| 3980 | |
| 3981 | |
| 3982 | strncat (tmp, &lookup[(l >> 18) & 0x3F], 1); |
| 3983 | strncat (tmp, &lookup[(l >> 12) & 0x3F], 1); |
| 3984 | |
| 3985 | if (i + 1 < length) |
| 3986 | strncat (tmp, &lookup[(l >> 6) & 0x3F], 1); |
| 3987 | if (i + 2 < length) |
| 3988 | strncat (tmp, &lookup[l & 0x3F], 1); |
| 3989 | } |
| 3990 | |
| 3991 | if (length % 3) |
| 3992 | strncat (tmp, "===", 3 - length % 3); |
| 3993 | |
| 3994 | return tmp; |
| 3995 | } |
| 3996 | |
| 3997 | |
| 3998 | static long |
| 3999 | get_file_size (const char *filename) |
| 4000 | { |
| 4001 | FILE *fp; |
| 4002 | |
| 4003 | fp = fopen (filename, "rb"); |
| 4004 | if (fp) |
| 4005 | { |
| 4006 | long size; |
| 4007 | |
| 4008 | if ((0 != fseek (fp, 0, SEEK_END)) || (-1 == (size = ftell (fp)))) |
| 4009 | size = 0; |
| 4010 | |
| 4011 | fclose (fp); |
| 4012 | |
| 4013 | return size; |
| 4014 | } |
| 4015 | else |
| 4016 | return 0; |
| 4017 | } |
| 4018 | |
| 4019 | static char * |
| 4020 | load_file (const char *filename) |
| 4021 | { |
| 4022 | FILE *fp; |
| 4023 | char *buffer; |
| 4024 | long size; |
| 4025 | |
| 4026 | size = get_file_size (filename); |
| 4027 | if (size == 0) |
| 4028 | return NULL; |
| 4029 | |
| 4030 | fp = fopen (filename, "rb"); |
| 4031 | if (!fp) |
| 4032 | return NULL; |
| 4033 | |
| 4034 | buffer = malloc (size); |
| 4035 | if (!buffer) |
| 4036 | { |
| 4037 | fclose (fp); |
| 4038 | return NULL; |
| 4039 | } |
| 4040 | |
| 4041 | if (size != fread (buffer, 1, size, fp)) |
| 4042 | { |
| 4043 | free (buffer); |
| 4044 | buffer = NULL; |
| 4045 | } |
| 4046 | |
| 4047 | fclose (fp); |
| 4048 | return buffer; |
| 4049 | } |
| 4050 | |
| 4051 | static int |
| 4052 | ask_for_authentication (struct MHD_Connection *connection, const char *realm) |
| 4053 | { |
| 4054 | int ret; |
| 4055 | struct MHD_Response *response; |
| 4056 | char *headervalue; |
| 4057 | const char *strbase = "Basic realm="; |
| 4058 | |
| 4059 | response = MHD_create_response_from_buffer (0, NULL, |
| 4060 | MHD_RESPMEM_PERSISTENT); |
| 4061 | if (!response) |
| 4062 | return MHD_NO; |
| 4063 | |
| 4064 | headervalue = malloc (strlen (strbase) + strlen (realm) + 1); |
| 4065 | if (!headervalue) |
| 4066 | return MHD_NO; |
| 4067 | |
| 4068 | strcpy (headervalue, strbase); |
| 4069 | strcat (headervalue, realm); |
| 4070 | |
| 4071 | ret = MHD_add_response_header (response, "WWW-Authenticate", headervalue); |
| 4072 | free (headervalue); |
| 4073 | if (!ret) |
| 4074 | { |
| 4075 | MHD_destroy_response (response); |
| 4076 | return MHD_NO; |
| 4077 | } |
| 4078 | |
| 4079 | ret = MHD_queue_response (connection, MHD_HTTP_UNAUTHORIZED, response); |
| 4080 | |
| 4081 | MHD_destroy_response (response); |
| 4082 | |
| 4083 | return ret; |
| 4084 | } |
| 4085 | |
| 4086 | static int |
| 4087 | is_authenticated (struct MHD_Connection *connection, |
| 4088 | const char *username, const char *password) |
| 4089 | { |
| 4090 | const char *headervalue; |
| 4091 | char *expected_b64, *expected; |
| 4092 | const char *strbase = "Basic "; |
| 4093 | int authenticated; |
| 4094 | |
| 4095 | headervalue = |
| 4096 | MHD_lookup_connection_value (connection, MHD_HEADER_KIND, |
| 4097 | "Authorization"); |
| 4098 | if (NULL == headervalue) |
| 4099 | return 0; |
| 4100 | if (0 != strncmp (headervalue, strbase, strlen (strbase))) |
| 4101 | return 0; |
| 4102 | |
| 4103 | expected = malloc (strlen (username) + 1 + strlen (password) + 1); |
| 4104 | if (NULL == expected) |
| 4105 | return 0; |
| 4106 | |
| 4107 | strcpy (expected, username); |
| 4108 | strcat (expected, ":"); |
| 4109 | strcat (expected, password); |
| 4110 | |
| 4111 | expected_b64 = string_to_base64 (expected); |
| 4112 | free (expected); |
| 4113 | if (NULL == expected_b64) |
| 4114 | return 0; |
| 4115 | |
| 4116 | authenticated = |
| 4117 | (strcmp (headervalue + strlen (strbase), expected_b64) == 0); |
| 4118 | |
| 4119 | free (expected_b64); |
| 4120 | |
| 4121 | return authenticated; |
| 4122 | } |
| 4123 | |
| 4124 | |
| 4125 | static int |
| 4126 | secret_page (struct MHD_Connection *connection) |
| 4127 | { |
| 4128 | int ret; |
| 4129 | struct MHD_Response *response; |
| 4130 | const char *page = "<html><body>A secret.</body></html>"; |
| 4131 | |
| 4132 | response = |
| 4133 | MHD_create_response_from_buffer (strlen (page), (void *) page, |
| 4134 | MHD_RESPMEM_PERSISTENT); |
| 4135 | if (!response) |
| 4136 | return MHD_NO; |
| 4137 | |
| 4138 | ret = MHD_queue_response (connection, MHD_HTTP_OK, response); |
| 4139 | MHD_destroy_response (response); |
| 4140 | |
| 4141 | return ret; |
| 4142 | } |
| 4143 | |
| 4144 | |
| 4145 | static int |
| 4146 | answer_to_connection (void *cls, struct MHD_Connection *connection, |
| 4147 | const char *url, const char *method, |
| 4148 | const char *version, const char *upload_data, |
| 4149 | size_t *upload_data_size, void **con_cls) |
| 4150 | { |
| 4151 | if (0 != strcmp (method, "GET")) |
| 4152 | return MHD_NO; |
| 4153 | if (NULL == *con_cls) |
| 4154 | { |
| 4155 | *con_cls = connection; |
| 4156 | return MHD_YES; |
| 4157 | } |
| 4158 | |
| 4159 | if (!is_authenticated (connection, USER, PASSWORD)) |
| 4160 | return ask_for_authentication (connection, REALM); |
| 4161 | |
| 4162 | return secret_page (connection); |
| 4163 | } |
| 4164 | |
| 4165 | |
| 4166 | int |
| 4167 | main () |
| 4168 | { |
| 4169 | struct MHD_Daemon *daemon; |
| 4170 | char *key_pem; |
| 4171 | char *cert_pem; |
| 4172 | |
| 4173 | key_pem = load_file (SERVERKEYFILE); |
| 4174 | cert_pem = load_file (SERVERCERTFILE); |
| 4175 | |
| 4176 | if ((key_pem == NULL) || (cert_pem == NULL)) |
| 4177 | { |
| 4178 | printf ("The key/certificate files could not be read.\n"); |
| 4179 | return 1; |
| 4180 | } |
| 4181 | |
| 4182 | daemon = |
| 4183 | MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_SSL, PORT, NULL, |
| 4184 | NULL, &answer_to_connection, NULL, |
| 4185 | MHD_OPTION_HTTPS_MEM_KEY, key_pem, |
| 4186 | MHD_OPTION_HTTPS_MEM_CERT, cert_pem, MHD_OPTION_END); |
| 4187 | if (NULL == daemon) |
| 4188 | { |
| 4189 | printf ("%s\n", cert_pem); |
| 4190 | |
| 4191 | free (key_pem); |
| 4192 | free (cert_pem); |
| 4193 | |
| 4194 | return 1; |
| 4195 | } |
| 4196 | |
| 4197 | (void) getchar (); |
| 4198 | |
| 4199 | MHD_stop_daemon (daemon); |
| 4200 | free (key_pem); |
| 4201 | free (cert_pem); |
| 4202 | |
| 4203 | return 0; |
| 4204 | } |
| 4205 | |
| 4206 | |
| 4207 | |
| 4208 | Tag Table: |
| 4209 | Node: Top866 |
| 4210 | Node: Introduction1917 |
| 4211 | Node: Hello browser example3223 |
| 4212 | Node: Exploring requests14247 |
| 4213 | Node: Response headers19643 |
| 4214 | Node: Supporting basic authentication27522 |
| 4215 | Node: Processing POST data34913 |
| 4216 | Node: Improved processing of POST data43534 |
| 4217 | Node: Session management54177 |
| 4218 | Node: Adding a layer of security57072 |
| 4219 | Node: Bibliography71602 |
| 4220 | Node: License text72797 |
| 4221 | Node: Example programs97972 |
| 4222 | Node: hellobrowser.c98285 |
| 4223 | Node: logging.c99828 |
| 4224 | Node: responseheaders.c101411 |
| 4225 | Node: basicauthentication.c104035 |
| 4226 | Node: simplepost.c106574 |
| 4227 | Node: largepost.c112254 |
| 4228 | Node: sessions.c119619 |
| 4229 | Node: tlsauthentication.c141964 |
| 4230 | |
| 4231 | End Tag Table |