Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame^] | 1 | /* |
| 2 | |
| 3 | clientloop.c |
| 4 | |
| 5 | Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | |
| 7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | All rights reserved |
| 9 | |
| 10 | |
| 11 | Created: Sat Sep 23 12:23:57 1995 ylo |
| 12 | |
| 13 | The main loop for the interactive session (client side). |
| 14 | |
| 15 | */ |
| 16 | |
| 17 | #include "includes.h" |
| 18 | RCSID("$Id: clientloop.c,v 1.1 1999/10/27 03:42:44 damien Exp $"); |
| 19 | |
| 20 | #include "xmalloc.h" |
| 21 | #include "ssh.h" |
| 22 | #include "packet.h" |
| 23 | #include "buffer.h" |
| 24 | #include "authfd.h" |
| 25 | |
| 26 | /* Flag indicating whether quiet mode is on. */ |
| 27 | extern int quiet_flag; |
| 28 | |
| 29 | /* Flag indicating that stdin should be redirected from /dev/null. */ |
| 30 | extern int stdin_null_flag; |
| 31 | |
| 32 | /* Name of the host we are connecting to. This is the name given on the |
| 33 | command line, or the HostName specified for the user-supplied name |
| 34 | in a configuration file. */ |
| 35 | extern char *host; |
| 36 | |
| 37 | /* Flag to indicate that we have received a window change signal which has |
| 38 | not yet been processed. This will cause a message indicating the new |
| 39 | window size to be sent to the server a little later. This is volatile |
| 40 | because this is updated in a signal handler. */ |
| 41 | static volatile int received_window_change_signal = 0; |
| 42 | |
| 43 | /* Terminal modes, as saved by enter_raw_mode. */ |
| 44 | static struct termios saved_tio; |
| 45 | |
| 46 | /* Flag indicating whether we are in raw mode. This is used by enter_raw_mode |
| 47 | and leave_raw_mode. */ |
| 48 | static int in_raw_mode = 0; |
| 49 | |
| 50 | /* Flag indicating whether the user\'s terminal is in non-blocking mode. */ |
| 51 | static int in_non_blocking_mode = 0; |
| 52 | |
| 53 | /* Common data for the client loop code. */ |
| 54 | static int escape_pending; /* Last character was the escape character */ |
| 55 | static int last_was_cr; /* Last character was a newline. */ |
| 56 | static int exit_status; /* Used to store the exit status of the command. */ |
| 57 | static int stdin_eof; /* EOF has been encountered on standard error. */ |
| 58 | static Buffer stdin_buffer; /* Buffer for stdin data. */ |
| 59 | static Buffer stdout_buffer; /* Buffer for stdout data. */ |
| 60 | static Buffer stderr_buffer; /* Buffer for stderr data. */ |
| 61 | static unsigned int buffer_high; /* Soft max buffer size. */ |
| 62 | static int max_fd; /* Maximum file descriptor number in select(). */ |
| 63 | static int connection_in; /* Connection to server (input). */ |
| 64 | static int connection_out; /* Connection to server (output). */ |
| 65 | static unsigned long stdin_bytes, stdout_bytes, stderr_bytes; |
| 66 | static int quit_pending; /* Set to non-zero to quit the client loop. */ |
| 67 | static int escape_char; /* Escape character. */ |
| 68 | |
| 69 | /* Returns the user\'s terminal to normal mode if it had been put in raw |
| 70 | mode. */ |
| 71 | |
| 72 | void leave_raw_mode() |
| 73 | { |
| 74 | if (!in_raw_mode) |
| 75 | return; |
| 76 | in_raw_mode = 0; |
| 77 | if (tcsetattr(fileno(stdin), TCSADRAIN, &saved_tio) < 0) |
| 78 | perror("tcsetattr"); |
| 79 | |
| 80 | fatal_remove_cleanup((void (*)(void *))leave_raw_mode, NULL); |
| 81 | } |
| 82 | |
| 83 | /* Puts the user\'s terminal in raw mode. */ |
| 84 | |
| 85 | void enter_raw_mode() |
| 86 | { |
| 87 | struct termios tio; |
| 88 | |
| 89 | if (tcgetattr(fileno(stdin), &tio) < 0) |
| 90 | perror("tcgetattr"); |
| 91 | saved_tio = tio; |
| 92 | tio.c_iflag |= IGNPAR; |
| 93 | tio.c_iflag &= ~(ISTRIP|INLCR|IGNCR|ICRNL|IXON|IXANY|IXOFF); |
| 94 | tio.c_lflag &= ~(ISIG|ICANON|ECHO|ECHOE|ECHOK|ECHONL); |
| 95 | #ifdef IEXTEN |
| 96 | tio.c_lflag &= ~IEXTEN; |
| 97 | #endif /* IEXTEN */ |
| 98 | tio.c_oflag &= ~OPOST; |
| 99 | tio.c_cc[VMIN] = 1; |
| 100 | tio.c_cc[VTIME] = 0; |
| 101 | if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) < 0) |
| 102 | perror("tcsetattr"); |
| 103 | in_raw_mode = 1; |
| 104 | |
| 105 | fatal_add_cleanup((void (*)(void *))leave_raw_mode, NULL); |
| 106 | } |
| 107 | |
| 108 | /* Puts stdin terminal in non-blocking mode. */ |
| 109 | |
| 110 | /* Restores stdin to blocking mode. */ |
| 111 | |
| 112 | void leave_non_blocking() |
| 113 | { |
| 114 | if (in_non_blocking_mode) |
| 115 | { |
| 116 | (void)fcntl(fileno(stdin), F_SETFL, 0); |
| 117 | in_non_blocking_mode = 0; |
| 118 | fatal_remove_cleanup((void (*)(void *))leave_non_blocking, NULL); |
| 119 | } |
| 120 | } |
| 121 | |
| 122 | void enter_non_blocking() |
| 123 | { |
| 124 | in_non_blocking_mode = 1; |
| 125 | (void)fcntl(fileno(stdin), F_SETFL, O_NONBLOCK); |
| 126 | fatal_add_cleanup((void (*)(void *))leave_non_blocking, NULL); |
| 127 | } |
| 128 | |
| 129 | /* Signal handler for the window change signal (SIGWINCH). This just |
| 130 | sets a flag indicating that the window has changed. */ |
| 131 | |
| 132 | void window_change_handler(int sig) |
| 133 | { |
| 134 | received_window_change_signal = 1; |
| 135 | signal(SIGWINCH, window_change_handler); |
| 136 | } |
| 137 | |
| 138 | /* Signal handler for signals that cause the program to terminate. These |
| 139 | signals must be trapped to restore terminal modes. */ |
| 140 | |
| 141 | void signal_handler(int sig) |
| 142 | { |
| 143 | if (in_raw_mode) |
| 144 | leave_raw_mode(); |
| 145 | if (in_non_blocking_mode) |
| 146 | leave_non_blocking(); |
| 147 | channel_stop_listening(); |
| 148 | packet_close(); |
| 149 | fatal("Killed by signal %d.", sig); |
| 150 | } |
| 151 | |
| 152 | /* Returns current time in seconds from Jan 1, 1970 with the maximum available |
| 153 | resolution. */ |
| 154 | |
| 155 | double get_current_time() |
| 156 | { |
| 157 | struct timeval tv; |
| 158 | gettimeofday(&tv, NULL); |
| 159 | return (double)tv.tv_sec + (double)tv.tv_usec / 1000000.0; |
| 160 | } |
| 161 | |
| 162 | /* This is called when the interactive is entered. This checks if there |
| 163 | is an EOF coming on stdin. We must check this explicitly, as select() |
| 164 | does not appear to wake up when redirecting from /dev/null. */ |
| 165 | |
| 166 | void client_check_initial_eof_on_stdin() |
| 167 | { |
| 168 | int len; |
| 169 | char buf[1]; |
| 170 | |
| 171 | /* If standard input is to be "redirected from /dev/null", we simply |
| 172 | mark that we have seen an EOF and send an EOF message to the server. |
| 173 | Otherwise, we try to read a single character; it appears that for some |
| 174 | files, such /dev/null, select() never wakes up for read for this |
| 175 | descriptor, which means that we never get EOF. This way we will get |
| 176 | the EOF if stdin comes from /dev/null or similar. */ |
| 177 | if (stdin_null_flag) |
| 178 | { |
| 179 | /* Fake EOF on stdin. */ |
| 180 | debug("Sending eof."); |
| 181 | stdin_eof = 1; |
| 182 | packet_start(SSH_CMSG_EOF); |
| 183 | packet_send(); |
| 184 | } |
| 185 | else |
| 186 | { |
| 187 | /* Enter non-blocking mode for stdin. */ |
| 188 | enter_non_blocking(); |
| 189 | |
| 190 | /* Check for immediate EOF on stdin. */ |
| 191 | len = read(fileno(stdin), buf, 1); |
| 192 | if (len == 0) |
| 193 | { |
| 194 | /* EOF. Record that we have seen it and send EOF to server. */ |
| 195 | debug("Sending eof."); |
| 196 | stdin_eof = 1; |
| 197 | packet_start(SSH_CMSG_EOF); |
| 198 | packet_send(); |
| 199 | } |
| 200 | else |
| 201 | if (len > 0) |
| 202 | { |
| 203 | /* Got data. We must store the data in the buffer, and also |
| 204 | process it as an escape character if appropriate. */ |
| 205 | if ((unsigned char)buf[0] == escape_char) |
| 206 | escape_pending = 1; |
| 207 | else |
| 208 | { |
| 209 | buffer_append(&stdin_buffer, buf, 1); |
| 210 | stdin_bytes += 1; |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | /* Leave non-blocking mode. */ |
| 215 | leave_non_blocking(); |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /* Get packets from the connection input buffer, and process them as long |
| 220 | as there are packets available. */ |
| 221 | |
| 222 | void client_process_buffered_input_packets() |
| 223 | { |
| 224 | int type; |
| 225 | char *data; |
| 226 | unsigned int data_len; |
| 227 | int payload_len; |
| 228 | |
| 229 | /* Process any buffered packets from the server. */ |
| 230 | while (!quit_pending && (type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) |
| 231 | { |
| 232 | switch (type) |
| 233 | { |
| 234 | |
| 235 | case SSH_SMSG_STDOUT_DATA: |
| 236 | data = packet_get_string(&data_len); |
| 237 | packet_integrity_check(payload_len, 4 + data_len, type); |
| 238 | buffer_append(&stdout_buffer, data, data_len); |
| 239 | stdout_bytes += data_len; |
| 240 | memset(data, 0, data_len); |
| 241 | xfree(data); |
| 242 | break; |
| 243 | |
| 244 | case SSH_SMSG_STDERR_DATA: |
| 245 | data = packet_get_string(&data_len); |
| 246 | packet_integrity_check(payload_len, 4 + data_len, type); |
| 247 | buffer_append(&stderr_buffer, data, data_len); |
| 248 | stdout_bytes += data_len; |
| 249 | memset(data, 0, data_len); |
| 250 | xfree(data); |
| 251 | break; |
| 252 | |
| 253 | case SSH_SMSG_EXITSTATUS: |
| 254 | packet_integrity_check(payload_len, 4, type); |
| 255 | exit_status = packet_get_int(); |
| 256 | /* Acknowledge the exit. */ |
| 257 | packet_start(SSH_CMSG_EXIT_CONFIRMATION); |
| 258 | packet_send(); |
| 259 | /* Must wait for packet to be sent since we are exiting the |
| 260 | loop. */ |
| 261 | packet_write_wait(); |
| 262 | /* Flag that we want to exit. */ |
| 263 | quit_pending = 1; |
| 264 | break; |
| 265 | |
| 266 | case SSH_SMSG_X11_OPEN: |
| 267 | x11_input_open(payload_len); |
| 268 | break; |
| 269 | |
| 270 | case SSH_MSG_PORT_OPEN: |
| 271 | channel_input_port_open(payload_len); |
| 272 | break; |
| 273 | |
| 274 | case SSH_SMSG_AGENT_OPEN: |
| 275 | packet_integrity_check(payload_len, 4, type); |
| 276 | auth_input_open_request(); |
| 277 | break; |
| 278 | |
| 279 | case SSH_MSG_CHANNEL_OPEN_CONFIRMATION: |
| 280 | packet_integrity_check(payload_len, 4 + 4, type); |
| 281 | channel_input_open_confirmation(); |
| 282 | break; |
| 283 | |
| 284 | case SSH_MSG_CHANNEL_OPEN_FAILURE: |
| 285 | packet_integrity_check(payload_len, 4, type); |
| 286 | channel_input_open_failure(); |
| 287 | break; |
| 288 | |
| 289 | case SSH_MSG_CHANNEL_DATA: |
| 290 | channel_input_data(payload_len); |
| 291 | break; |
| 292 | |
| 293 | case SSH_MSG_CHANNEL_CLOSE: |
| 294 | packet_integrity_check(payload_len, 4, type); |
| 295 | channel_input_close(); |
| 296 | break; |
| 297 | |
| 298 | case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION: |
| 299 | packet_integrity_check(payload_len, 4, type); |
| 300 | channel_input_close_confirmation(); |
| 301 | break; |
| 302 | |
| 303 | default: |
| 304 | /* Any unknown packets received during the actual session |
| 305 | cause the session to terminate. This is intended to make |
| 306 | debugging easier since no confirmations are sent. Any |
| 307 | compatible protocol extensions must be negotiated during |
| 308 | the preparatory phase. */ |
| 309 | packet_disconnect("Protocol error during session: type %d", |
| 310 | type); |
| 311 | } |
| 312 | } |
| 313 | } |
| 314 | |
| 315 | /* Make packets from buffered stdin data, and buffer them for sending to |
| 316 | the connection. */ |
| 317 | |
| 318 | void client_make_packets_from_stdin_data() |
| 319 | { |
| 320 | unsigned int len; |
| 321 | |
| 322 | /* Send buffered stdin data to the server. */ |
| 323 | while (buffer_len(&stdin_buffer) > 0 && |
| 324 | packet_not_very_much_data_to_write()) |
| 325 | { |
| 326 | len = buffer_len(&stdin_buffer); |
| 327 | if (len > 32768) |
| 328 | len = 32768; /* Keep the packets at reasonable size. */ |
| 329 | packet_start(SSH_CMSG_STDIN_DATA); |
| 330 | packet_put_string(buffer_ptr(&stdin_buffer), len); |
| 331 | packet_send(); |
| 332 | buffer_consume(&stdin_buffer, len); |
| 333 | /* If we have a pending EOF, send it now. */ |
| 334 | if (stdin_eof && buffer_len(&stdin_buffer) == 0) |
| 335 | { |
| 336 | packet_start(SSH_CMSG_EOF); |
| 337 | packet_send(); |
| 338 | } |
| 339 | } |
| 340 | } |
| 341 | |
| 342 | /* Checks if the client window has changed, and sends a packet about it to |
| 343 | the server if so. The actual change is detected elsewhere (by a software |
| 344 | interrupt on Unix); this just checks the flag and sends a message if |
| 345 | appropriate. */ |
| 346 | |
| 347 | void client_check_window_change() |
| 348 | { |
| 349 | /* Send possible window change message to the server. */ |
| 350 | if (received_window_change_signal) |
| 351 | { |
| 352 | struct winsize ws; |
| 353 | |
| 354 | /* Clear the window change indicator. */ |
| 355 | received_window_change_signal = 0; |
| 356 | |
| 357 | /* Read new window size. */ |
| 358 | if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) >= 0) |
| 359 | { |
| 360 | /* Successful, send the packet now. */ |
| 361 | packet_start(SSH_CMSG_WINDOW_SIZE); |
| 362 | packet_put_int(ws.ws_row); |
| 363 | packet_put_int(ws.ws_col); |
| 364 | packet_put_int(ws.ws_xpixel); |
| 365 | packet_put_int(ws.ws_ypixel); |
| 366 | packet_send(); |
| 367 | } |
| 368 | } |
| 369 | } |
| 370 | |
| 371 | /* Waits until the client can do something (some data becomes available on |
| 372 | one of the file descriptors). */ |
| 373 | |
| 374 | void client_wait_until_can_do_something(fd_set *readset, fd_set *writeset) |
| 375 | { |
| 376 | /* Initialize select masks. */ |
| 377 | FD_ZERO(readset); |
| 378 | |
| 379 | /* Read from the connection, unless our buffers are full. */ |
| 380 | if (buffer_len(&stdout_buffer) < buffer_high && |
| 381 | buffer_len(&stderr_buffer) < buffer_high && |
| 382 | channel_not_very_much_buffered_data()) |
| 383 | FD_SET(connection_in, readset); |
| 384 | |
| 385 | /* Read from stdin, unless we have seen EOF or have very much buffered |
| 386 | data to send to the server. */ |
| 387 | if (!stdin_eof && packet_not_very_much_data_to_write()) |
| 388 | FD_SET(fileno(stdin), readset); |
| 389 | |
| 390 | FD_ZERO(writeset); |
| 391 | |
| 392 | /* Add any selections by the channel mechanism. */ |
| 393 | channel_prepare_select(readset, writeset); |
| 394 | |
| 395 | /* Select server connection if have data to write to the server. */ |
| 396 | if (packet_have_data_to_write()) |
| 397 | FD_SET(connection_out, writeset); |
| 398 | |
| 399 | /* Select stdout if have data in buffer. */ |
| 400 | if (buffer_len(&stdout_buffer) > 0) |
| 401 | FD_SET(fileno(stdout), writeset); |
| 402 | |
| 403 | /* Select stderr if have data in buffer. */ |
| 404 | if (buffer_len(&stderr_buffer) > 0) |
| 405 | FD_SET(fileno(stderr), writeset); |
| 406 | |
| 407 | /* Update maximum file descriptor number, if appropriate. */ |
| 408 | if (channel_max_fd() > max_fd) |
| 409 | max_fd = channel_max_fd(); |
| 410 | |
| 411 | /* Wait for something to happen. This will suspend the process until |
| 412 | some selected descriptor can be read, written, or has some other |
| 413 | event pending. Note: if you want to implement SSH_MSG_IGNORE |
| 414 | messages to fool traffic analysis, this might be the place to do |
| 415 | it: just have a random timeout for the select, and send a random |
| 416 | SSH_MSG_IGNORE packet when the timeout expires. */ |
| 417 | if (select(max_fd + 1, readset, writeset, NULL, NULL) < 0) |
| 418 | { |
| 419 | char buf[100]; |
| 420 | /* Some systems fail to clear these automatically. */ |
| 421 | FD_ZERO(readset); |
| 422 | FD_ZERO(writeset); |
| 423 | if (errno == EINTR) |
| 424 | return; |
| 425 | /* Note: we might still have data in the buffers. */ |
| 426 | snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno)); |
| 427 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 428 | stderr_bytes += strlen(buf); |
| 429 | quit_pending = 1; |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | void client_suspend_self() |
| 434 | { |
| 435 | struct winsize oldws, newws; |
| 436 | |
| 437 | /* Flush stdout and stderr buffers. */ |
| 438 | if (buffer_len(&stdout_buffer) > 0) |
| 439 | write(fileno(stdout), |
| 440 | buffer_ptr(&stdout_buffer), |
| 441 | buffer_len(&stdout_buffer)); |
| 442 | if (buffer_len(&stderr_buffer) > 0) |
| 443 | write(fileno(stderr), |
| 444 | buffer_ptr(&stderr_buffer), |
| 445 | buffer_len(&stderr_buffer)); |
| 446 | |
| 447 | /* Leave raw mode. */ |
| 448 | leave_raw_mode(); |
| 449 | |
| 450 | /* Free (and clear) the buffer to reduce the |
| 451 | amount of data that gets written to swap. */ |
| 452 | buffer_free(&stdin_buffer); |
| 453 | buffer_free(&stdout_buffer); |
| 454 | buffer_free(&stderr_buffer); |
| 455 | |
| 456 | /* Save old window size. */ |
| 457 | ioctl(fileno(stdin), TIOCGWINSZ, &oldws); |
| 458 | |
| 459 | /* Send the suspend signal to the program |
| 460 | itself. */ |
| 461 | kill(getpid(), SIGTSTP); |
| 462 | |
| 463 | /* Check if the window size has changed. */ |
| 464 | if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 && |
| 465 | (oldws.ws_row != newws.ws_row || oldws.ws_col != newws.ws_col || |
| 466 | oldws.ws_xpixel != newws.ws_xpixel || |
| 467 | oldws.ws_ypixel != newws.ws_ypixel)) |
| 468 | received_window_change_signal = 1; |
| 469 | |
| 470 | /* OK, we have been continued by the user. |
| 471 | Reinitialize buffers. */ |
| 472 | buffer_init(&stdin_buffer); |
| 473 | buffer_init(&stdout_buffer); |
| 474 | buffer_init(&stderr_buffer); |
| 475 | |
| 476 | /* Re-enter raw mode. */ |
| 477 | enter_raw_mode(); |
| 478 | } |
| 479 | |
| 480 | void client_process_input(fd_set *readset) |
| 481 | { |
| 482 | int len, pid; |
| 483 | char buf[8192], *s; |
| 484 | |
| 485 | /* Read input from the server, and add any such data to the buffer of the |
| 486 | packet subsystem. */ |
| 487 | if (FD_ISSET(connection_in, readset)) |
| 488 | { |
| 489 | /* Read as much as possible. */ |
| 490 | len = read(connection_in, buf, sizeof(buf)); |
| 491 | if (len == 0) |
| 492 | { |
| 493 | /* Received EOF. The remote host has closed the connection. */ |
| 494 | snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n", |
| 495 | host); |
| 496 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 497 | stderr_bytes += strlen(buf); |
| 498 | quit_pending = 1; |
| 499 | return; |
| 500 | } |
| 501 | |
| 502 | /* There is a kernel bug on Solaris that causes select to sometimes |
| 503 | wake up even though there is no data available. */ |
| 504 | if (len < 0 && errno == EAGAIN) |
| 505 | len = 0; |
| 506 | |
| 507 | if (len < 0) |
| 508 | { |
| 509 | /* An error has encountered. Perhaps there is a network |
| 510 | problem. */ |
| 511 | snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n", |
| 512 | host, strerror(errno)); |
| 513 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 514 | stderr_bytes += strlen(buf); |
| 515 | quit_pending = 1; |
| 516 | return; |
| 517 | } |
| 518 | packet_process_incoming(buf, len); |
| 519 | } |
| 520 | |
| 521 | /* Read input from stdin. */ |
| 522 | if (FD_ISSET(fileno(stdin), readset)) |
| 523 | { |
| 524 | /* Read as much as possible. */ |
| 525 | len = read(fileno(stdin), buf, sizeof(buf)); |
| 526 | if (len <= 0) |
| 527 | { |
| 528 | /* Received EOF or error. They are treated similarly, |
| 529 | except that an error message is printed if it was |
| 530 | an error condition. */ |
| 531 | if (len < 0) |
| 532 | { |
| 533 | snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno)); |
| 534 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 535 | stderr_bytes += strlen(buf); |
| 536 | } |
| 537 | /* Mark that we have seen EOF. */ |
| 538 | stdin_eof = 1; |
| 539 | /* Send an EOF message to the server unless there is data |
| 540 | in the buffer. If there is data in the buffer, no message |
| 541 | will be sent now. Code elsewhere will send the EOF |
| 542 | when the buffer becomes empty if stdin_eof is set. */ |
| 543 | if (buffer_len(&stdin_buffer) == 0) |
| 544 | { |
| 545 | packet_start(SSH_CMSG_EOF); |
| 546 | packet_send(); |
| 547 | } |
| 548 | } |
| 549 | else |
| 550 | if (escape_char == -1) |
| 551 | { |
| 552 | /* Normal successful read, and no escape character. Just |
| 553 | append the data to buffer. */ |
| 554 | buffer_append(&stdin_buffer, buf, len); |
| 555 | stdin_bytes += len; |
| 556 | } |
| 557 | else |
| 558 | { |
| 559 | /* Normal, successful read. But we have an escape character |
| 560 | and have to process the characters one by one. */ |
| 561 | unsigned int i; |
| 562 | for (i = 0; i < len; i++) |
| 563 | { |
| 564 | unsigned char ch; |
| 565 | /* Get one character at a time. */ |
| 566 | ch = buf[i]; |
| 567 | |
| 568 | /* Check if we have a pending escape character. */ |
| 569 | if (escape_pending) |
| 570 | { |
| 571 | /* We have previously seen an escape character. */ |
| 572 | /* Clear the flag now. */ |
| 573 | escape_pending = 0; |
| 574 | /* Process the escaped character. */ |
| 575 | switch (ch) |
| 576 | { |
| 577 | case '.': |
| 578 | /* Terminate the connection. */ |
| 579 | snprintf(buf, sizeof buf, "%c.\r\n", escape_char); |
| 580 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 581 | stderr_bytes += strlen(buf); |
| 582 | quit_pending = 1; |
| 583 | return; |
| 584 | |
| 585 | case 'Z' - 64: |
| 586 | /* Suspend the program. */ |
| 587 | /* Print a message to that effect to the user. */ |
| 588 | snprintf(buf, sizeof buf, "%c^Z\r\n", escape_char); |
| 589 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 590 | stderr_bytes += strlen(buf); |
| 591 | |
| 592 | /* Restore terminal modes and suspend. */ |
| 593 | client_suspend_self(); |
| 594 | |
| 595 | /* We have been continued. */ |
| 596 | continue; |
| 597 | |
| 598 | case '&': |
| 599 | /* Detach the program (continue to serve connections, |
| 600 | but put in background and no more new |
| 601 | connections). */ |
| 602 | if (!stdin_eof) |
| 603 | { |
| 604 | /* Sending SSH_CMSG_EOF alone does not always |
| 605 | appear to be enough. So we try to send an |
| 606 | EOF character first. */ |
| 607 | packet_start(SSH_CMSG_STDIN_DATA); |
| 608 | packet_put_string("\004", 1); |
| 609 | packet_send(); |
| 610 | /* Close stdin. */ |
| 611 | stdin_eof = 1; |
| 612 | if (buffer_len(&stdin_buffer) == 0) |
| 613 | { |
| 614 | packet_start(SSH_CMSG_EOF); |
| 615 | packet_send(); |
| 616 | } |
| 617 | } |
| 618 | /* Restore tty modes. */ |
| 619 | leave_raw_mode(); |
| 620 | |
| 621 | /* Stop listening for new connections. */ |
| 622 | channel_stop_listening(); |
| 623 | |
| 624 | printf("%c& [backgrounded]\n", escape_char); |
| 625 | |
| 626 | /* Fork into background. */ |
| 627 | pid = fork(); |
| 628 | if (pid < 0) |
| 629 | { |
| 630 | error("fork: %.100s", strerror(errno)); |
| 631 | continue; |
| 632 | } |
| 633 | if (pid != 0) |
| 634 | { /* This is the parent. */ |
| 635 | /* The parent just exits. */ |
| 636 | exit(0); |
| 637 | } |
| 638 | |
| 639 | /* The child continues serving connections. */ |
| 640 | continue; |
| 641 | |
| 642 | case '?': |
| 643 | snprintf(buf, sizeof buf, "%c?\r\n\ |
| 644 | Supported escape sequences:\r\n\ |
| 645 | ~. - terminate connection\r\n\ |
| 646 | ~^Z - suspend ssh\r\n\ |
| 647 | ~# - list forwarded connections\r\n\ |
| 648 | ~& - background ssh (when waiting for connections to terminate)\r\n\ |
| 649 | ~? - this message\r\n\ |
| 650 | ~~ - send the escape character by typing it twice\r\n\ |
| 651 | (Note that escapes are only recognized immediately after newline.)\r\n", |
| 652 | escape_char); |
| 653 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 654 | continue; |
| 655 | |
| 656 | case '#': |
| 657 | snprintf(buf, sizeof buf, "%c#\r\n", escape_char); |
| 658 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 659 | s = channel_open_message(); |
| 660 | buffer_append(&stderr_buffer, s, strlen(s)); |
| 661 | xfree(s); |
| 662 | continue; |
| 663 | |
| 664 | default: |
| 665 | if (ch != escape_char) |
| 666 | { |
| 667 | /* Escape character followed by non-special |
| 668 | character. Append both to the input |
| 669 | buffer. */ |
| 670 | buf[0] = escape_char; |
| 671 | buf[1] = ch; |
| 672 | buffer_append(&stdin_buffer, buf, 2); |
| 673 | stdin_bytes += 2; |
| 674 | continue; |
| 675 | } |
| 676 | /* Note that escape character typed twice falls through |
| 677 | here; the latter gets processed as a normal |
| 678 | character below. */ |
| 679 | break; |
| 680 | } |
| 681 | } |
| 682 | else |
| 683 | { |
| 684 | /* The previous character was not an escape char. |
| 685 | Check if this is an escape. */ |
| 686 | if (last_was_cr && ch == escape_char) |
| 687 | { |
| 688 | /* It is. Set the flag and continue to next |
| 689 | character. */ |
| 690 | escape_pending = 1; |
| 691 | continue; |
| 692 | } |
| 693 | } |
| 694 | |
| 695 | /* Normal character. Record whether it was a newline, |
| 696 | and append it to the buffer. */ |
| 697 | last_was_cr = (ch == '\r' || ch == '\n'); |
| 698 | buf[0] = ch; |
| 699 | buffer_append(&stdin_buffer, buf, 1); |
| 700 | stdin_bytes += 1; |
| 701 | continue; |
| 702 | } |
| 703 | } |
| 704 | } |
| 705 | } |
| 706 | |
| 707 | void client_process_output(fd_set *writeset) |
| 708 | { |
| 709 | int len; |
| 710 | char buf[100]; |
| 711 | |
| 712 | /* Write buffered output to stdout. */ |
| 713 | if (FD_ISSET(fileno(stdout), writeset)) |
| 714 | { |
| 715 | /* Write as much data as possible. */ |
| 716 | len = write(fileno(stdout), buffer_ptr(&stdout_buffer), |
| 717 | buffer_len(&stdout_buffer)); |
| 718 | if (len <= 0) |
| 719 | { |
| 720 | if (errno == EAGAIN) |
| 721 | len = 0; |
| 722 | else |
| 723 | { |
| 724 | /* An error or EOF was encountered. Put an error message |
| 725 | to stderr buffer. */ |
| 726 | snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno)); |
| 727 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 728 | stderr_bytes += strlen(buf); |
| 729 | quit_pending = 1; |
| 730 | return; |
| 731 | } |
| 732 | } |
| 733 | /* Consume printed data from the buffer. */ |
| 734 | buffer_consume(&stdout_buffer, len); |
| 735 | } |
| 736 | |
| 737 | /* Write buffered output to stderr. */ |
| 738 | if (FD_ISSET(fileno(stderr), writeset)) |
| 739 | { |
| 740 | /* Write as much data as possible. */ |
| 741 | len = write(fileno(stderr), buffer_ptr(&stderr_buffer), |
| 742 | buffer_len(&stderr_buffer)); |
| 743 | if (len <= 0) { |
| 744 | if (errno == EAGAIN) |
| 745 | len = 0; |
| 746 | else |
| 747 | { |
| 748 | /* EOF or error, but can't even print error message. */ |
| 749 | quit_pending = 1; |
| 750 | return; |
| 751 | } |
| 752 | } |
| 753 | /* Consume printed characters from the buffer. */ |
| 754 | buffer_consume(&stderr_buffer, len); |
| 755 | } |
| 756 | } |
| 757 | |
| 758 | /* Implements the interactive session with the server. This is called |
| 759 | after the user has been authenticated, and a command has been |
| 760 | started on the remote host. If escape_char != -1, it is the character |
| 761 | used as an escape character for terminating or suspending the |
| 762 | session. */ |
| 763 | |
| 764 | int client_loop(int have_pty, int escape_char_arg) |
| 765 | { |
| 766 | double start_time, total_time; |
| 767 | int len; |
| 768 | char buf[100]; |
| 769 | |
| 770 | debug("Entering interactive session."); |
| 771 | |
| 772 | start_time = get_current_time(); |
| 773 | |
| 774 | /* Initialize variables. */ |
| 775 | escape_pending = 0; |
| 776 | last_was_cr = 1; |
| 777 | exit_status = -1; |
| 778 | stdin_eof = 0; |
| 779 | buffer_high = 64 * 1024; |
| 780 | connection_in = packet_get_connection_in(); |
| 781 | connection_out = packet_get_connection_out(); |
| 782 | max_fd = connection_in; |
| 783 | if (connection_out > max_fd) |
| 784 | max_fd = connection_out; |
| 785 | stdin_bytes = 0; |
| 786 | stdout_bytes = 0; |
| 787 | stderr_bytes = 0; |
| 788 | quit_pending = 0; |
| 789 | escape_char = escape_char_arg; |
| 790 | |
| 791 | /* Initialize buffers. */ |
| 792 | buffer_init(&stdin_buffer); |
| 793 | buffer_init(&stdout_buffer); |
| 794 | buffer_init(&stderr_buffer); |
| 795 | |
| 796 | /* Set signal handlers to restore non-blocking mode. */ |
| 797 | signal(SIGINT, signal_handler); |
| 798 | signal(SIGQUIT, signal_handler); |
| 799 | signal(SIGTERM, signal_handler); |
| 800 | signal(SIGPIPE, SIG_IGN); |
| 801 | if (have_pty) |
| 802 | signal(SIGWINCH, window_change_handler); |
| 803 | |
| 804 | /* Enter raw mode if have a pseudo terminal. */ |
| 805 | if (have_pty) |
| 806 | enter_raw_mode(); |
| 807 | |
| 808 | /* Check if we should immediately send of on stdin. */ |
| 809 | client_check_initial_eof_on_stdin(); |
| 810 | |
| 811 | /* Main loop of the client for the interactive session mode. */ |
| 812 | while (!quit_pending) |
| 813 | { |
| 814 | fd_set readset, writeset; |
| 815 | |
| 816 | /* Precess buffered packets sent by the server. */ |
| 817 | client_process_buffered_input_packets(); |
| 818 | |
| 819 | /* Make packets of buffered stdin data, and buffer them for sending |
| 820 | to the server. */ |
| 821 | client_make_packets_from_stdin_data(); |
| 822 | |
| 823 | /* Make packets from buffered channel data, and buffer them for sending |
| 824 | to the server. */ |
| 825 | if (packet_not_very_much_data_to_write()) |
| 826 | channel_output_poll(); |
| 827 | |
| 828 | /* Check if the window size has changed, and buffer a message about |
| 829 | it to the server if so. */ |
| 830 | client_check_window_change(); |
| 831 | |
| 832 | if (quit_pending) |
| 833 | break; |
| 834 | |
| 835 | /* Wait until we have something to do (something becomes available |
| 836 | on one of the descriptors). */ |
| 837 | client_wait_until_can_do_something(&readset, &writeset); |
| 838 | |
| 839 | if (quit_pending) |
| 840 | break; |
| 841 | |
| 842 | /* Do channel operations. */ |
| 843 | channel_after_select(&readset, &writeset); |
| 844 | |
| 845 | /* Process input from the connection and from stdin. Buffer any data |
| 846 | that is available. */ |
| 847 | client_process_input(&readset); |
| 848 | |
| 849 | /* Process output to stdout and stderr. Output to the connection |
| 850 | is processed elsewhere (above). */ |
| 851 | client_process_output(&writeset); |
| 852 | |
| 853 | /* Send as much buffered packet data as possible to the sender. */ |
| 854 | if (FD_ISSET(connection_out, &writeset)) |
| 855 | packet_write_poll(); |
| 856 | } |
| 857 | |
| 858 | /* Terminate the session. */ |
| 859 | |
| 860 | /* Stop watching for window change. */ |
| 861 | if (have_pty) |
| 862 | signal(SIGWINCH, SIG_DFL); |
| 863 | |
| 864 | /* Stop listening for connections. */ |
| 865 | channel_stop_listening(); |
| 866 | |
| 867 | /* In interactive mode (with pseudo tty) display a message indicating that |
| 868 | the connection has been closed. */ |
| 869 | if (have_pty && !quiet_flag) |
| 870 | { |
| 871 | snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host); |
| 872 | buffer_append(&stderr_buffer, buf, strlen(buf)); |
| 873 | stderr_bytes += strlen(buf); |
| 874 | } |
| 875 | |
| 876 | /* Output any buffered data for stdout. */ |
| 877 | while (buffer_len(&stdout_buffer) > 0) |
| 878 | { |
| 879 | len = write(fileno(stdout), buffer_ptr(&stdout_buffer), |
| 880 | buffer_len(&stdout_buffer)); |
| 881 | if (len <= 0) |
| 882 | { |
| 883 | error("Write failed flushing stdout buffer."); |
| 884 | break; |
| 885 | } |
| 886 | buffer_consume(&stdout_buffer, len); |
| 887 | } |
| 888 | |
| 889 | /* Output any buffered data for stderr. */ |
| 890 | while (buffer_len(&stderr_buffer) > 0) |
| 891 | { |
| 892 | len = write(fileno(stderr), buffer_ptr(&stderr_buffer), |
| 893 | buffer_len(&stderr_buffer)); |
| 894 | if (len <= 0) |
| 895 | { |
| 896 | error("Write failed flushing stderr buffer."); |
| 897 | break; |
| 898 | } |
| 899 | buffer_consume(&stderr_buffer, len); |
| 900 | } |
| 901 | |
| 902 | /* Leave raw mode. */ |
| 903 | if (have_pty) |
| 904 | leave_raw_mode(); |
| 905 | |
| 906 | /* Clear and free any buffers. */ |
| 907 | memset(buf, 0, sizeof(buf)); |
| 908 | buffer_free(&stdin_buffer); |
| 909 | buffer_free(&stdout_buffer); |
| 910 | buffer_free(&stderr_buffer); |
| 911 | |
| 912 | /* Report bytes transferred, and transfer rates. */ |
| 913 | total_time = get_current_time() - start_time; |
| 914 | debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds", |
| 915 | stdin_bytes, stdout_bytes, stderr_bytes, total_time); |
| 916 | if (total_time > 0) |
| 917 | debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f", |
| 918 | stdin_bytes / total_time, stdout_bytes / total_time, |
| 919 | stderr_bytes / total_time); |
| 920 | |
| 921 | /* Return the exit status of the program. */ |
| 922 | debug("Exit status %d", exit_status); |
| 923 | return exit_status; |
| 924 | } |