Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 4 | * All rights reserved |
| 5 | * Created: Sun Sep 10 00:30:37 1995 ylo |
| 6 | * Server main loop for handling the interactive session. |
| 7 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 8 | |
| 9 | #include "includes.h" |
| 10 | #include "xmalloc.h" |
| 11 | #include "ssh.h" |
| 12 | #include "packet.h" |
| 13 | #include "buffer.h" |
| 14 | #include "servconf.h" |
| 15 | #include "pty.h" |
| 16 | |
| 17 | static Buffer stdin_buffer; /* Buffer for stdin data. */ |
| 18 | static Buffer stdout_buffer; /* Buffer for stdout data. */ |
| 19 | static Buffer stderr_buffer; /* Buffer for stderr data. */ |
| 20 | static int fdin; /* Descriptor for stdin (for writing) */ |
| 21 | static int fdout; /* Descriptor for stdout (for reading); |
| 22 | May be same number as fdin. */ |
| 23 | static int fderr; /* Descriptor for stderr. May be -1. */ |
| 24 | static long stdin_bytes = 0; /* Number of bytes written to stdin. */ |
| 25 | static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ |
| 26 | static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ |
| 27 | static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ |
| 28 | static int stdin_eof = 0; /* EOF message received from client. */ |
| 29 | static int fdout_eof = 0; /* EOF encountered reading from fdout. */ |
| 30 | static int fderr_eof = 0; /* EOF encountered readung from fderr. */ |
| 31 | static int connection_in; /* Connection to client (input). */ |
| 32 | static int connection_out; /* Connection to client (output). */ |
| 33 | static unsigned int buffer_high;/* "Soft" max buffer size. */ |
| 34 | static int max_fd; /* Max file descriptor number for select(). */ |
| 35 | |
| 36 | /* This SIGCHLD kludge is used to detect when the child exits. The server |
| 37 | will exit after that, as soon as forwarded connections have terminated. */ |
| 38 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 39 | static int child_pid; /* Pid of the child. */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 40 | static volatile int child_terminated; /* The child has terminated. */ |
| 41 | static volatile int child_wait_status; /* Status from wait(). */ |
| 42 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 43 | void |
| 44 | sigchld_handler(int sig) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 45 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 46 | int save_errno = errno; |
| 47 | int wait_pid; |
| 48 | debug("Received SIGCHLD."); |
| 49 | wait_pid = wait((int *) &child_wait_status); |
| 50 | if (wait_pid != -1) { |
| 51 | if (wait_pid != child_pid) |
| 52 | error("Strange, got SIGCHLD and wait returned pid %d but child is %d", |
| 53 | wait_pid, child_pid); |
| 54 | if (WIFEXITED(child_wait_status) || |
| 55 | WIFSIGNALED(child_wait_status)) |
| 56 | child_terminated = 1; |
| 57 | } |
| 58 | signal(SIGCHLD, sigchld_handler); |
| 59 | errno = save_errno; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 60 | } |
| 61 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 62 | /* |
| 63 | * Process any buffered packets that have been received from the client. |
| 64 | */ |
| 65 | void |
| 66 | process_buffered_input_packets() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 67 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 68 | int type; |
| 69 | char *data; |
| 70 | unsigned int data_len; |
| 71 | int row, col, xpixel, ypixel; |
| 72 | int payload_len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 73 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 74 | /* Process buffered packets from the client. */ |
| 75 | while ((type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) { |
| 76 | switch (type) { |
| 77 | case SSH_CMSG_STDIN_DATA: |
| 78 | /* Stdin data from the client. Append it to the buffer. */ |
| 79 | /* Ignore any data if the client has closed stdin. */ |
| 80 | if (fdin == -1) |
| 81 | break; |
| 82 | data = packet_get_string(&data_len); |
| 83 | packet_integrity_check(payload_len, (4 + data_len), type); |
| 84 | buffer_append(&stdin_buffer, data, data_len); |
| 85 | memset(data, 0, data_len); |
| 86 | xfree(data); |
| 87 | break; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 88 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 89 | case SSH_CMSG_EOF: |
| 90 | /* Eof from the client. The stdin descriptor to |
| 91 | the program will be closed when all buffered |
| 92 | data has drained. */ |
| 93 | debug("EOF received for stdin."); |
| 94 | packet_integrity_check(payload_len, 0, type); |
| 95 | stdin_eof = 1; |
| 96 | break; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 97 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 98 | case SSH_CMSG_WINDOW_SIZE: |
| 99 | debug("Window change received."); |
| 100 | packet_integrity_check(payload_len, 4 * 4, type); |
| 101 | row = packet_get_int(); |
| 102 | col = packet_get_int(); |
| 103 | xpixel = packet_get_int(); |
| 104 | ypixel = packet_get_int(); |
| 105 | if (fdin != -1) |
| 106 | pty_change_window_size(fdin, row, col, xpixel, ypixel); |
| 107 | break; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 108 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 109 | case SSH_MSG_PORT_OPEN: |
| 110 | debug("Received port open request."); |
| 111 | channel_input_port_open(payload_len); |
| 112 | break; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 113 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 114 | case SSH_MSG_CHANNEL_OPEN_CONFIRMATION: |
| 115 | debug("Received channel open confirmation."); |
| 116 | packet_integrity_check(payload_len, 4 + 4, type); |
| 117 | channel_input_open_confirmation(); |
| 118 | break; |
| 119 | |
| 120 | case SSH_MSG_CHANNEL_OPEN_FAILURE: |
| 121 | debug("Received channel open failure."); |
| 122 | packet_integrity_check(payload_len, 4, type); |
| 123 | channel_input_open_failure(); |
| 124 | break; |
| 125 | |
| 126 | case SSH_MSG_CHANNEL_DATA: |
| 127 | channel_input_data(payload_len); |
| 128 | break; |
| 129 | |
| 130 | case SSH_MSG_CHANNEL_CLOSE: |
| 131 | debug("Received channel close."); |
| 132 | packet_integrity_check(payload_len, 4, type); |
| 133 | channel_input_close(); |
| 134 | break; |
| 135 | |
| 136 | case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION: |
| 137 | debug("Received channel close confirmation."); |
| 138 | packet_integrity_check(payload_len, 4, type); |
| 139 | channel_input_close_confirmation(); |
| 140 | break; |
| 141 | |
| 142 | default: |
| 143 | /* In this phase, any unexpected messages cause a |
| 144 | protocol error. This is to ease debugging; |
| 145 | also, since no confirmations are sent messages, |
| 146 | unprocessed unknown messages could cause |
| 147 | strange problems. Any compatible protocol |
| 148 | extensions must be negotiated before entering |
| 149 | the interactive session. */ |
| 150 | packet_disconnect("Protocol error during session: type %d", |
| 151 | type); |
| 152 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 153 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 154 | } |
| 155 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 156 | /* |
| 157 | * Make packets from buffered stderr data, and buffer it for sending |
| 158 | * to the client. |
| 159 | */ |
| 160 | void |
| 161 | make_packets_from_stderr_data() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 162 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 163 | int len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 164 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 165 | /* Send buffered stderr data to the client. */ |
| 166 | while (buffer_len(&stderr_buffer) > 0 && |
| 167 | packet_not_very_much_data_to_write()) { |
| 168 | len = buffer_len(&stderr_buffer); |
| 169 | if (packet_is_interactive()) { |
| 170 | if (len > 512) |
| 171 | len = 512; |
| 172 | } else { |
| 173 | /* Keep the packets at reasonable size. */ |
| 174 | if (len > packet_get_maxsize()) |
| 175 | len = packet_get_maxsize(); |
| 176 | } |
| 177 | packet_start(SSH_SMSG_STDERR_DATA); |
| 178 | packet_put_string(buffer_ptr(&stderr_buffer), len); |
| 179 | packet_send(); |
| 180 | buffer_consume(&stderr_buffer, len); |
| 181 | stderr_bytes += len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 182 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 183 | } |
| 184 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 185 | /* |
| 186 | * Make packets from buffered stdout data, and buffer it for sending to the |
| 187 | * client. |
| 188 | */ |
| 189 | void |
| 190 | make_packets_from_stdout_data() |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 191 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 192 | int len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 193 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 194 | /* Send buffered stdout data to the client. */ |
| 195 | while (buffer_len(&stdout_buffer) > 0 && |
| 196 | packet_not_very_much_data_to_write()) { |
| 197 | len = buffer_len(&stdout_buffer); |
| 198 | if (packet_is_interactive()) { |
| 199 | if (len > 512) |
| 200 | len = 512; |
| 201 | } else { |
| 202 | /* Keep the packets at reasonable size. */ |
| 203 | if (len > packet_get_maxsize()) |
| 204 | len = packet_get_maxsize(); |
| 205 | } |
| 206 | packet_start(SSH_SMSG_STDOUT_DATA); |
| 207 | packet_put_string(buffer_ptr(&stdout_buffer), len); |
| 208 | packet_send(); |
| 209 | buffer_consume(&stdout_buffer, len); |
| 210 | stdout_bytes += len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 211 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 212 | } |
| 213 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 214 | /* |
| 215 | * Sleep in select() until we can do something. This will initialize the |
| 216 | * select masks. Upon return, the masks will indicate which descriptors |
| 217 | * have data or can accept data. Optionally, a maximum time can be specified |
| 218 | * for the duration of the wait (0 = infinite). |
| 219 | */ |
| 220 | void |
| 221 | wait_until_can_do_something(fd_set * readset, fd_set * writeset, |
| 222 | unsigned int max_time_milliseconds) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 223 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 224 | struct timeval tv, *tvp; |
| 225 | int ret; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 226 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 227 | /* When select fails we restart from here. */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 228 | retry_select: |
| 229 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 230 | /* Initialize select() masks. */ |
| 231 | FD_ZERO(readset); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 232 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 233 | /* Read packets from the client unless we have too much buffered |
| 234 | stdin or channel data. */ |
| 235 | if (buffer_len(&stdin_buffer) < 4096 && |
| 236 | channel_not_very_much_buffered_data()) |
| 237 | FD_SET(connection_in, readset); |
| 238 | |
| 239 | /* If there is not too much data already buffered going to the |
| 240 | client, try to get some more data from the program. */ |
| 241 | if (packet_not_very_much_data_to_write()) { |
| 242 | if (!fdout_eof) |
| 243 | FD_SET(fdout, readset); |
| 244 | if (!fderr_eof) |
| 245 | FD_SET(fderr, readset); |
| 246 | } |
| 247 | FD_ZERO(writeset); |
| 248 | |
| 249 | /* Set masks for channel descriptors. */ |
| 250 | channel_prepare_select(readset, writeset); |
| 251 | |
| 252 | /* If we have buffered packet data going to the client, mark that |
| 253 | descriptor. */ |
| 254 | if (packet_have_data_to_write()) |
| 255 | FD_SET(connection_out, writeset); |
| 256 | |
| 257 | /* If we have buffered data, try to write some of that data to the |
| 258 | program. */ |
| 259 | if (fdin != -1 && buffer_len(&stdin_buffer) > 0) |
| 260 | FD_SET(fdin, writeset); |
| 261 | |
| 262 | /* Update the maximum descriptor number if appropriate. */ |
| 263 | if (channel_max_fd() > max_fd) |
| 264 | max_fd = channel_max_fd(); |
| 265 | |
| 266 | /* If child has terminated and there is enough buffer space to |
| 267 | read from it, then read as much as is available and exit. */ |
| 268 | if (child_terminated && packet_not_very_much_data_to_write()) |
| 269 | if (max_time_milliseconds == 0) |
| 270 | max_time_milliseconds = 100; |
| 271 | |
| 272 | if (max_time_milliseconds == 0) |
| 273 | tvp = NULL; |
| 274 | else { |
| 275 | tv.tv_sec = max_time_milliseconds / 1000; |
| 276 | tv.tv_usec = 1000 * (max_time_milliseconds % 1000); |
| 277 | tvp = &tv; |
| 278 | } |
| 279 | |
| 280 | /* Wait for something to happen, or the timeout to expire. */ |
| 281 | ret = select(max_fd + 1, readset, writeset, NULL, tvp); |
| 282 | |
| 283 | if (ret < 0) { |
| 284 | if (errno != EINTR) |
| 285 | error("select: %.100s", strerror(errno)); |
| 286 | else |
| 287 | goto retry_select; |
| 288 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 289 | } |
| 290 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 291 | /* |
| 292 | * Processes input from the client and the program. Input data is stored |
| 293 | * in buffers and processed later. |
| 294 | */ |
| 295 | void |
| 296 | process_input(fd_set * readset) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 297 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 298 | int len; |
| 299 | char buf[16384]; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 300 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 301 | /* Read and buffer any input data from the client. */ |
| 302 | if (FD_ISSET(connection_in, readset)) { |
| 303 | len = read(connection_in, buf, sizeof(buf)); |
| 304 | if (len == 0) { |
| 305 | verbose("Connection closed by remote host."); |
| 306 | fatal_cleanup(); |
| 307 | } |
| 308 | /* There is a kernel bug on Solaris that causes select to |
| 309 | sometimes wake up even though there is no data |
| 310 | available. */ |
| 311 | if (len < 0 && errno == EAGAIN) |
| 312 | len = 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 313 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 314 | if (len < 0) { |
| 315 | verbose("Read error from remote host: %.100s", strerror(errno)); |
| 316 | fatal_cleanup(); |
| 317 | } |
| 318 | /* Buffer any received data. */ |
| 319 | packet_process_incoming(buf, len); |
| 320 | } |
| 321 | /* Read and buffer any available stdout data from the program. */ |
| 322 | if (!fdout_eof && FD_ISSET(fdout, readset)) { |
| 323 | len = read(fdout, buf, sizeof(buf)); |
| 324 | if (len <= 0) |
| 325 | fdout_eof = 1; |
| 326 | else { |
| 327 | buffer_append(&stdout_buffer, buf, len); |
| 328 | fdout_bytes += len; |
| 329 | } |
| 330 | } |
| 331 | /* Read and buffer any available stderr data from the program. */ |
| 332 | if (!fderr_eof && FD_ISSET(fderr, readset)) { |
| 333 | len = read(fderr, buf, sizeof(buf)); |
| 334 | if (len <= 0) |
| 335 | fderr_eof = 1; |
| 336 | else |
| 337 | buffer_append(&stderr_buffer, buf, len); |
| 338 | } |
| 339 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 340 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 341 | /* |
| 342 | * Sends data from internal buffers to client program stdin. |
| 343 | */ |
| 344 | void |
| 345 | process_output(fd_set * writeset) |
| 346 | { |
| 347 | int len; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 348 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 349 | /* Write buffered data to program stdin. */ |
| 350 | if (fdin != -1 && FD_ISSET(fdin, writeset)) { |
| 351 | len = write(fdin, buffer_ptr(&stdin_buffer), |
| 352 | buffer_len(&stdin_buffer)); |
| 353 | if (len <= 0) { |
| 354 | #ifdef USE_PIPES |
| 355 | close(fdin); |
| 356 | #else |
| 357 | if (fdout == -1) |
| 358 | close(fdin); |
| 359 | else |
| 360 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ |
| 361 | #endif |
| 362 | fdin = -1; |
| 363 | } else { |
| 364 | /* Successful write. Consume the data from the buffer. */ |
| 365 | buffer_consume(&stdin_buffer, len); |
| 366 | /* Update the count of bytes written to the program. */ |
| 367 | stdin_bytes += len; |
| 368 | } |
| 369 | } |
| 370 | /* Send any buffered packet data to the client. */ |
| 371 | if (FD_ISSET(connection_out, writeset)) |
| 372 | packet_write_poll(); |
| 373 | } |
| 374 | |
| 375 | /* |
| 376 | * Wait until all buffered output has been sent to the client. |
| 377 | * This is used when the program terminates. |
| 378 | */ |
| 379 | void |
| 380 | drain_output() |
| 381 | { |
| 382 | /* Send any buffered stdout data to the client. */ |
| 383 | if (buffer_len(&stdout_buffer) > 0) { |
| 384 | packet_start(SSH_SMSG_STDOUT_DATA); |
| 385 | packet_put_string(buffer_ptr(&stdout_buffer), |
| 386 | buffer_len(&stdout_buffer)); |
| 387 | packet_send(); |
| 388 | /* Update the count of sent bytes. */ |
| 389 | stdout_bytes += buffer_len(&stdout_buffer); |
| 390 | } |
| 391 | /* Send any buffered stderr data to the client. */ |
| 392 | if (buffer_len(&stderr_buffer) > 0) { |
| 393 | packet_start(SSH_SMSG_STDERR_DATA); |
| 394 | packet_put_string(buffer_ptr(&stderr_buffer), |
| 395 | buffer_len(&stderr_buffer)); |
| 396 | packet_send(); |
| 397 | /* Update the count of sent bytes. */ |
| 398 | stderr_bytes += buffer_len(&stderr_buffer); |
| 399 | } |
| 400 | /* Wait until all buffered data has been written to the client. */ |
| 401 | packet_write_wait(); |
| 402 | } |
| 403 | |
| 404 | /* |
| 405 | * Performs the interactive session. This handles data transmission between |
| 406 | * the client and the program. Note that the notion of stdin, stdout, and |
| 407 | * stderr in this function is sort of reversed: this function writes to |
| 408 | * stdin (of the child program), and reads from stdout and stderr (of the |
| 409 | * child program). |
| 410 | */ |
| 411 | void |
| 412 | server_loop(int pid, int fdin_arg, int fdout_arg, int fderr_arg) |
| 413 | { |
| 414 | int wait_status, wait_pid; /* Status and pid returned by wait(). */ |
| 415 | int waiting_termination = 0; /* Have displayed waiting close message. */ |
| 416 | unsigned int max_time_milliseconds; |
| 417 | unsigned int previous_stdout_buffer_bytes; |
| 418 | unsigned int stdout_buffer_bytes; |
| 419 | int type; |
| 420 | |
| 421 | debug("Entering interactive session."); |
| 422 | |
| 423 | /* Initialize the SIGCHLD kludge. */ |
| 424 | child_pid = pid; |
| 425 | child_terminated = 0; |
| 426 | signal(SIGCHLD, sigchld_handler); |
| 427 | |
| 428 | /* Initialize our global variables. */ |
| 429 | fdin = fdin_arg; |
| 430 | fdout = fdout_arg; |
| 431 | fderr = fderr_arg; |
| 432 | connection_in = packet_get_connection_in(); |
| 433 | connection_out = packet_get_connection_out(); |
| 434 | |
| 435 | previous_stdout_buffer_bytes = 0; |
| 436 | |
| 437 | /* Set approximate I/O buffer size. */ |
| 438 | if (packet_is_interactive()) |
| 439 | buffer_high = 4096; |
| 440 | else |
| 441 | buffer_high = 64 * 1024; |
| 442 | |
| 443 | /* Initialize max_fd to the maximum of the known file descriptors. */ |
| 444 | max_fd = fdin; |
| 445 | if (fdout > max_fd) |
| 446 | max_fd = fdout; |
| 447 | if (fderr != -1 && fderr > max_fd) |
| 448 | max_fd = fderr; |
| 449 | if (connection_in > max_fd) |
| 450 | max_fd = connection_in; |
| 451 | if (connection_out > max_fd) |
| 452 | max_fd = connection_out; |
| 453 | |
| 454 | /* Initialize Initialize buffers. */ |
| 455 | buffer_init(&stdin_buffer); |
| 456 | buffer_init(&stdout_buffer); |
| 457 | buffer_init(&stderr_buffer); |
| 458 | |
| 459 | /* If we have no separate fderr (which is the case when we have a |
| 460 | pty - there we cannot make difference between data sent to |
| 461 | stdout and stderr), indicate that we have seen an EOF from |
| 462 | stderr. This way we don\'t need to check the descriptor |
| 463 | everywhere. */ |
| 464 | if (fderr == -1) |
| 465 | fderr_eof = 1; |
| 466 | |
| 467 | /* Main loop of the server for the interactive session mode. */ |
| 468 | for (;;) { |
| 469 | fd_set readset, writeset; |
| 470 | |
| 471 | /* Process buffered packets from the client. */ |
| 472 | process_buffered_input_packets(); |
| 473 | |
| 474 | /* If we have received eof, and there is no more pending |
| 475 | input data, cause a real eof by closing fdin. */ |
| 476 | if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { |
| 477 | #ifdef USE_PIPES |
| 478 | close(fdin); |
| 479 | #else |
| 480 | if (fdout == -1) |
| 481 | close(fdin); |
| 482 | else |
| 483 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ |
| 484 | #endif |
| 485 | fdin = -1; |
| 486 | } |
| 487 | /* Make packets from buffered stderr data to send to the |
| 488 | client. */ |
| 489 | make_packets_from_stderr_data(); |
| 490 | |
| 491 | /* Make packets from buffered stdout data to send to the |
| 492 | client. If there is very little to send, this arranges |
| 493 | to not send them now, but to wait a short while to see |
| 494 | if we are getting more data. This is necessary, as some |
| 495 | systems wake up readers from a pty after each separate |
| 496 | character. */ |
| 497 | max_time_milliseconds = 0; |
| 498 | stdout_buffer_bytes = buffer_len(&stdout_buffer); |
| 499 | if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && |
| 500 | stdout_buffer_bytes != previous_stdout_buffer_bytes) { |
| 501 | /* try again after a while */ |
| 502 | max_time_milliseconds = 10; |
| 503 | } else { |
| 504 | /* Send it now. */ |
| 505 | make_packets_from_stdout_data(); |
| 506 | } |
| 507 | previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); |
| 508 | |
| 509 | /* Send channel data to the client. */ |
| 510 | if (packet_not_very_much_data_to_write()) |
| 511 | channel_output_poll(); |
| 512 | |
| 513 | /* Bail out of the loop if the program has closed its |
| 514 | output descriptors, and we have no more data to send to |
| 515 | the client, and there is no pending buffered data. */ |
| 516 | if (fdout_eof && fderr_eof && !packet_have_data_to_write() && |
| 517 | buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { |
| 518 | if (!channel_still_open()) |
| 519 | goto quit; |
| 520 | if (!waiting_termination) { |
| 521 | const char *s = "Waiting for forwarded connections to terminate...\r\n"; |
| 522 | char *cp; |
| 523 | waiting_termination = 1; |
| 524 | buffer_append(&stderr_buffer, s, strlen(s)); |
| 525 | |
| 526 | /* Display list of open channels. */ |
| 527 | cp = channel_open_message(); |
| 528 | buffer_append(&stderr_buffer, cp, strlen(cp)); |
| 529 | xfree(cp); |
| 530 | } |
| 531 | } |
| 532 | /* Sleep in select() until we can do something. */ |
| 533 | wait_until_can_do_something(&readset, &writeset, |
| 534 | max_time_milliseconds); |
| 535 | |
| 536 | /* Process any channel events. */ |
| 537 | channel_after_select(&readset, &writeset); |
| 538 | |
| 539 | /* Process input from the client and from program stdout/stderr. */ |
| 540 | process_input(&readset); |
| 541 | |
| 542 | /* Process output to the client and to program stdin. */ |
| 543 | process_output(&writeset); |
| 544 | } |
| 545 | |
| 546 | quit: |
| 547 | /* Cleanup and termination code. */ |
| 548 | |
| 549 | /* Wait until all output has been sent to the client. */ |
| 550 | drain_output(); |
| 551 | |
| 552 | debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", |
| 553 | stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); |
| 554 | |
| 555 | /* Free and clear the buffers. */ |
| 556 | buffer_free(&stdin_buffer); |
| 557 | buffer_free(&stdout_buffer); |
| 558 | buffer_free(&stderr_buffer); |
| 559 | |
| 560 | /* Close the file descriptors. */ |
| 561 | if (fdout != -1) |
| 562 | close(fdout); |
| 563 | fdout = -1; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 564 | fdout_eof = 1; |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 565 | if (fderr != -1) |
| 566 | close(fderr); |
| 567 | fderr = -1; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 568 | fderr_eof = 1; |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame^] | 569 | if (fdin != -1) |
| 570 | close(fdin); |
| 571 | fdin = -1; |
| 572 | |
| 573 | /* Stop listening for channels; this removes unix domain sockets. */ |
| 574 | channel_stop_listening(); |
| 575 | |
| 576 | /* Wait for the child to exit. Get its exit status. */ |
| 577 | wait_pid = wait(&wait_status); |
| 578 | if (wait_pid < 0) { |
| 579 | /* |
| 580 | * It is possible that the wait was handled by SIGCHLD |
| 581 | * handler. This may result in either: this call |
| 582 | * returning with EINTR, or: this call returning ECHILD. |
| 583 | */ |
| 584 | if (child_terminated) |
| 585 | wait_status = child_wait_status; |
| 586 | else |
| 587 | packet_disconnect("wait: %.100s", strerror(errno)); |
| 588 | } else { |
| 589 | /* Check if it matches the process we forked. */ |
| 590 | if (wait_pid != pid) |
| 591 | error("Strange, wait returned pid %d, expected %d", |
| 592 | wait_pid, pid); |
| 593 | } |
| 594 | |
| 595 | /* We no longer want our SIGCHLD handler to be called. */ |
| 596 | signal(SIGCHLD, SIG_DFL); |
| 597 | |
| 598 | /* Check if it exited normally. */ |
| 599 | if (WIFEXITED(wait_status)) { |
| 600 | /* Yes, normal exit. Get exit status and send it to the client. */ |
| 601 | debug("Command exited with status %d.", WEXITSTATUS(wait_status)); |
| 602 | packet_start(SSH_SMSG_EXITSTATUS); |
| 603 | packet_put_int(WEXITSTATUS(wait_status)); |
| 604 | packet_send(); |
| 605 | packet_write_wait(); |
| 606 | |
| 607 | /* Wait for exit confirmation. Note that there might be |
| 608 | other packets coming before it; however, the program |
| 609 | has already died so we just ignore them. The client is |
| 610 | supposed to respond with the confirmation when it |
| 611 | receives the exit status. */ |
| 612 | do { |
| 613 | int plen; |
| 614 | type = packet_read(&plen); |
| 615 | } |
| 616 | while (type != SSH_CMSG_EXIT_CONFIRMATION); |
| 617 | |
| 618 | debug("Received exit confirmation."); |
| 619 | return; |
| 620 | } |
| 621 | /* Check if the program terminated due to a signal. */ |
| 622 | if (WIFSIGNALED(wait_status)) |
| 623 | packet_disconnect("Command terminated on signal %d.", |
| 624 | WTERMSIG(wait_status)); |
| 625 | |
| 626 | /* Some weird exit cause. Just exit. */ |
| 627 | packet_disconnect("wait returned status %04x.", wait_status); |
| 628 | /* NOTREACHED */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 629 | } |