clientloop.c

   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  * SSH2 support added by Markus Friedl.
  16  */
  17
  18 #include "includes.h"
  19 RCSID("$Id$");
  20
  21 #include "xmalloc.h"
  22 #include "ssh.h"
  23 #include "packet.h"
  24 #include "buffer.h"
  25 #include "authfd.h"
  26 #include "readconf.h"
  27
  28 #include "ssh2.h"
  29 #include "compat.h"
  30 #include "channels.h"
  31 #include "dispatch.h"
  32
  33
  34 /* Flag indicating that stdin should be redirected from /dev/null. */
  35 extern int stdin_null_flag;
  36
  37 /*
  38  * Name of the host we are connecting to.  This is the name given on the
  39  * command line, or the HostName specified for the user-supplied name in a
  40  * configuration file.
  41  */
  42 extern char *host;
  43
  44 /*
  45  * Flag to indicate that we have received a window change signal which has
  46  * not yet been processed.  This will cause a message indicating the new
  47  * window size to be sent to the server a little later.  This is volatile
  48  * because this is updated in a signal handler.
  49  */
  50 static volatile int received_window_change_signal = 0;
  51
  52 /* Terminal modes, as saved by enter_raw_mode. */
  53 static struct termios saved_tio;
  54
  55 /*
  56  * Flag indicating whether we are in raw mode.  This is used by
  57  * enter_raw_mode and leave_raw_mode.
  58  */
  59 static int in_raw_mode = 0;
  60
  61 /* Flag indicating whether the user\'s terminal is in non-blocking mode. */
  62 static int in_non_blocking_mode = 0;
  63
  64 /* Common data for the client loop code. */
  65 static int escape_pending;      /* Last character was the escape character */
  66 static int last_was_cr;         /* Last character was a newline. */
  67 static int exit_status;         /* Used to store the exit status of the command. */
  68 static int stdin_eof;           /* EOF has been encountered on standard error. */
  69 static Buffer stdin_buffer;     /* Buffer for stdin data. */
  70 static Buffer stdout_buffer;    /* Buffer for stdout data. */
  71 static Buffer stderr_buffer;    /* Buffer for stderr data. */
  72 static unsigned int buffer_high;/* Soft max buffer size. */
  73 static int max_fd;              /* Maximum file descriptor number in select(). */
  74 static int connection_in;       /* Connection to server (input). */
  75 static int connection_out;      /* Connection to server (output). */
  76 static unsigned long stdin_bytes, stdout_bytes, stderr_bytes;
  77 static int quit_pending;        /* Set to non-zero to quit the client loop. */
  78 static int escape_char;         /* Escape character. */
  79
  80
  81 void    client_init_dispatch(void);
  82 int     session_ident = -1;
  83
  84 /* Returns the user\'s terminal to normal mode if it had been put in raw mode. */
  85
  86 void
  87 leave_raw_mode()
  88 {
  89         if (!in_raw_mode)
  90                 return;
  91         in_raw_mode = 0;
  92         if (tcsetattr(fileno(stdin), TCSADRAIN, &saved_tio) < 0)
  93                 perror("tcsetattr");
  94
  95         fatal_remove_cleanup((void (*) (void *)) leave_raw_mode, NULL);
  96 }
  97
  98 /* Puts the user\'s terminal in raw mode. */
  99
 100 void
 101 enter_raw_mode()
 102 {
 103         struct termios tio;
 104
 105         if (tcgetattr(fileno(stdin), &tio) < 0)
 106                 perror("tcgetattr");
 107         saved_tio = tio;
 108         tio.c_iflag |= IGNPAR;
 109         tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
 110         tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
 111 #ifdef IEXTEN
 112         tio.c_lflag &= ~IEXTEN;
 113 #endif                          /* IEXTEN */
 114         tio.c_oflag &= ~OPOST;
 115         tio.c_cc[VMIN] = 1;
 116         tio.c_cc[VTIME] = 0;
 117         if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) < 0)
 118                 perror("tcsetattr");
 119         in_raw_mode = 1;
 120
 121         fatal_add_cleanup((void (*) (void *)) leave_raw_mode, NULL);
 122 }
 123
 124 /* Restores stdin to blocking mode. */
 125
 126 void
 127 leave_non_blocking()
 128 {
 129         if (in_non_blocking_mode) {
 130                 (void) fcntl(fileno(stdin), F_SETFL, 0);
 131                 in_non_blocking_mode = 0;
 132                 fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
 133         }
 134 }
 135
 136 /* Puts stdin terminal in non-blocking mode. */
 137
 138 void
 139 enter_non_blocking()
 140 {
 141         in_non_blocking_mode = 1;
 142         (void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
 143         fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
 144 }
 145
 146 /*
 147  * Signal handler for the window change signal (SIGWINCH).  This just sets a
 148  * flag indicating that the window has changed.
 149  */
 150
 151 void
 152 window_change_handler(int sig)
 153 {
 154         received_window_change_signal = 1;
 155         signal(SIGWINCH, window_change_handler);
 156 }
 157
 158 /*
 159  * Signal handler for signals that cause the program to terminate.  These
 160  * signals must be trapped to restore terminal modes.
 161  */
 162
 163 void
 164 signal_handler(int sig)
 165 {
 166         if (in_raw_mode)
 167                 leave_raw_mode();
 168         if (in_non_blocking_mode)
 169                 leave_non_blocking();
 170         channel_stop_listening();
 171         packet_close();
 172         fatal("Killed by signal %d.", sig);
 173 }
 174
 175 /*
 176  * Returns current time in seconds from Jan 1, 1970 with the maximum
 177  * available resolution.
 178  */
 179
 180 double
 181 get_current_time()
 182 {
 183         struct timeval tv;
 184         gettimeofday(&tv, NULL);
 185         return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
 186 }
 187
 188 /*
 189  * This is called when the interactive is entered.  This checks if there is
 190  * an EOF coming on stdin.  We must check this explicitly, as select() does
 191  * not appear to wake up when redirecting from /dev/null.
 192  */
 193
 194 void
 195 client_check_initial_eof_on_stdin()
 196 {
 197         int len;
 198         char buf[1];
 199
 200         /*
 201          * If standard input is to be "redirected from /dev/null", we simply
 202          * mark that we have seen an EOF and send an EOF message to the
 203          * server. Otherwise, we try to read a single character; it appears
 204          * that for some files, such /dev/null, select() never wakes up for
 205          * read for this descriptor, which means that we never get EOF.  This
 206          * way we will get the EOF if stdin comes from /dev/null or similar.
 207          */
 208         if (stdin_null_flag) {
 209                 /* Fake EOF on stdin. */
 210                 debug("Sending eof.");
 211                 stdin_eof = 1;
 212                 packet_start(SSH_CMSG_EOF);
 213                 packet_send();
 214         } else {
 215                 enter_non_blocking();
 216
 217                 /* Check for immediate EOF on stdin. */
 218                 len = read(fileno(stdin), buf, 1);
 219                 if (len == 0) {
 220                         /* EOF.  Record that we have seen it and send EOF to server. */
 221                         debug("Sending eof.");
 222                         stdin_eof = 1;
 223                         packet_start(SSH_CMSG_EOF);
 224                         packet_send();
 225                 } else if (len > 0) {
 226                         /*
 227                          * Got data.  We must store the data in the buffer,
 228                          * and also process it as an escape character if
 229                          * appropriate.
 230                          */
 231                         if ((unsigned char) buf[0] == escape_char)
 232                                 escape_pending = 1;
 233                         else {
 234                                 buffer_append(&stdin_buffer, buf, 1);
 235                                 stdin_bytes += 1;
 236                         }
 237                 }
 238                 leave_non_blocking();
 239         }
 240 }
 241
 242
 243 /*
 244  * Make packets from buffered stdin data, and buffer them for sending to the
 245  * connection.
 246  */
 247
 248 void
 249 client_make_packets_from_stdin_data()
 250 {
 251         unsigned int len;
 252
 253         /* Send buffered stdin data to the server. */
 254         while (buffer_len(&stdin_buffer) > 0 &&
 255                packet_not_very_much_data_to_write()) {
 256                 len = buffer_len(&stdin_buffer);
 257                 /* Keep the packets at reasonable size. */
 258                 if (len > packet_get_maxsize())
 259                         len = packet_get_maxsize();
 260                 packet_start(SSH_CMSG_STDIN_DATA);
 261                 packet_put_string(buffer_ptr(&stdin_buffer), len);
 262                 packet_send();
 263                 buffer_consume(&stdin_buffer, len);
 264                 /* If we have a pending EOF, send it now. */
 265                 if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
 266                         packet_start(SSH_CMSG_EOF);
 267                         packet_send();
 268                 }
 269         }
 270 }
 271
 272 /*
 273  * Checks if the client window has changed, and sends a packet about it to
 274  * the server if so.  The actual change is detected elsewhere (by a software
 275  * interrupt on Unix); this just checks the flag and sends a message if
 276  * appropriate.
 277  */
 278
 279 void
 280 client_check_window_change()
 281 {
 282         struct winsize ws;
 283
 284         if (! received_window_change_signal)
 285                 return;
 286         /** XXX race */
 287         received_window_change_signal = 0;
 288
 289         if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 290                 return;
 291
 292         debug("client_check_window_change: changed");
 293
 294         if (compat20) {
 295                 channel_request_start(session_ident, "window-change", 0);
 296                 packet_put_int(ws.ws_col);
 297                 packet_put_int(ws.ws_row);
 298                 packet_put_int(ws.ws_xpixel);
 299                 packet_put_int(ws.ws_ypixel);
 300                 packet_send();
 301         } else {
 302                 packet_start(SSH_CMSG_WINDOW_SIZE);
 303                 packet_put_int(ws.ws_row);
 304                 packet_put_int(ws.ws_col);
 305                 packet_put_int(ws.ws_xpixel);
 306                 packet_put_int(ws.ws_ypixel);
 307                 packet_send();
 308         }
 309 }
 310
 311 /*
 312  * Waits until the client can do something (some data becomes available on
 313  * one of the file descriptors).
 314  */
 315
 316 void
 317 client_wait_until_can_do_something(fd_set * readset, fd_set * writeset)
 318 {
 319         /*debug("client_wait_until_can_do_something"); */
 320
 321         /* Initialize select masks. */
 322         FD_ZERO(readset);
 323         FD_ZERO(writeset);
 324
 325         if (!compat20) {
 326                 /* Read from the connection, unless our buffers are full. */
 327                 if (buffer_len(&stdout_buffer) < buffer_high &&
 328                     buffer_len(&stderr_buffer) < buffer_high &&
 329                     channel_not_very_much_buffered_data())
 330                         FD_SET(connection_in, readset);
 331                 /*
 332                  * Read from stdin, unless we have seen EOF or have very much
 333                  * buffered data to send to the server.
 334                  */
 335                 if (!stdin_eof && packet_not_very_much_data_to_write())
 336                         FD_SET(fileno(stdin), readset);
 337
 338                 /* Select stdout/stderr if have data in buffer. */
 339                 if (buffer_len(&stdout_buffer) > 0)
 340                         FD_SET(fileno(stdout), writeset);
 341                 if (buffer_len(&stderr_buffer) > 0)
 342                         FD_SET(fileno(stderr), writeset);
 343         } else {
 344                 FD_SET(connection_in, readset);
 345         }
 346
 347         /* Add any selections by the channel mechanism. */
 348         channel_prepare_select(readset, writeset);
 349
 350         /* Select server connection if have data to write to the server. */
 351         if (packet_have_data_to_write())
 352                 FD_SET(connection_out, writeset);
 353
 354 /* move UP XXX */
 355         /* Update maximum file descriptor number, if appropriate. */
 356         if (channel_max_fd() > max_fd)
 357                 max_fd = channel_max_fd();
 358
 359         /*
 360          * Wait for something to happen.  This will suspend the process until
 361          * some selected descriptor can be read, written, or has some other
 362          * event pending. Note: if you want to implement SSH_MSG_IGNORE
 363          * messages to fool traffic analysis, this might be the place to do
 364          * it: just have a random timeout for the select, and send a random
 365          * SSH_MSG_IGNORE packet when the timeout expires.
 366          */
 367
 368         if (select(max_fd + 1, readset, writeset, NULL, NULL) < 0) {
 369                 char buf[100];
 370                 /* Some systems fail to clear these automatically. */
 371                 FD_ZERO(readset);
 372                 FD_ZERO(writeset);
 373                 if (errno == EINTR)
 374                         return;
 375                 /* Note: we might still have data in the buffers. */
 376                 snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
 377                 buffer_append(&stderr_buffer, buf, strlen(buf));
 378                 stderr_bytes += strlen(buf);
 379                 quit_pending = 1;
 380         }
 381 }
 382
 383 void
 384 client_suspend_self()
 385 {
 386         struct winsize oldws, newws;
 387
 388         /* Flush stdout and stderr buffers. */
 389         if (buffer_len(&stdout_buffer) > 0)
 390                 atomicio(write, fileno(stdout), buffer_ptr(&stdout_buffer),
 391                     buffer_len(&stdout_buffer));
 392         if (buffer_len(&stderr_buffer) > 0)
 393                 atomicio(write, fileno(stderr), buffer_ptr(&stderr_buffer),
 394                     buffer_len(&stderr_buffer));
 395
 396         leave_raw_mode();
 397
 398         /*
 399          * Free (and clear) the buffer to reduce the amount of data that gets
 400          * written to swap.
 401          */
 402         buffer_free(&stdin_buffer);
 403         buffer_free(&stdout_buffer);
 404         buffer_free(&stderr_buffer);
 405
 406         /* Save old window size. */
 407         ioctl(fileno(stdin), TIOCGWINSZ, &oldws);
 408
 409         /* Send the suspend signal to the program itself. */
 410         kill(getpid(), SIGTSTP);
 411
 412         /* Check if the window size has changed. */
 413         if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
 414             (oldws.ws_row != newws.ws_row ||
 415              oldws.ws_col != newws.ws_col ||
 416              oldws.ws_xpixel != newws.ws_xpixel ||
 417              oldws.ws_ypixel != newws.ws_ypixel))
 418                 received_window_change_signal = 1;
 419
 420         /* OK, we have been continued by the user. Reinitialize buffers. */
 421         buffer_init(&stdin_buffer);
 422         buffer_init(&stdout_buffer);
 423         buffer_init(&stderr_buffer);
 424
 425         enter_raw_mode();
 426 }
 427
 428 void
 429 client_process_net_input(fd_set * readset)
 430 {
 431         int len;
 432         char buf[8192];
 433
 434         /*
 435          * Read input from the server, and add any such data to the buffer of
 436          * the packet subsystem.
 437          */
 438         if (FD_ISSET(connection_in, readset)) {
 439                 /* Read as much as possible. */
 440                 len = read(connection_in, buf, sizeof(buf));
 441 /*debug("read connection_in len %d", len); XXX */
 442                 if (len == 0) {
 443                         /* Received EOF.  The remote host has closed the connection. */
 444                         snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n",
 445                                  host);
 446                         buffer_append(&stderr_buffer, buf, strlen(buf));
 447                         stderr_bytes += strlen(buf);
 448                         quit_pending = 1;
 449                         return;
 450                 }
 451                 /*
 452                  * There is a kernel bug on Solaris that causes select to
 453                  * sometimes wake up even though there is no data available.
 454                  */
 455                 if (len < 0 && errno == EAGAIN)
 456                         len = 0;
 457
 458                 if (len < 0) {
 459                         /* An error has encountered.  Perhaps there is a network problem. */
 460                         snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n",
 461                                  host, strerror(errno));
 462                         buffer_append(&stderr_buffer, buf, strlen(buf));
 463                         stderr_bytes += strlen(buf);
 464                         quit_pending = 1;
 465                         return;
 466                 }
 467                 packet_process_incoming(buf, len);
 468         }
 469 }
 470
 471 void
 472 client_process_input(fd_set * readset)
 473 {
 474         int len, pid;
 475         char buf[8192], *s;
 476
 477         /* Read input from stdin. */
 478         if (FD_ISSET(fileno(stdin), readset)) {
 479                 /* Read as much as possible. */
 480                 len = read(fileno(stdin), buf, sizeof(buf));
 481                 if (len <= 0) {
 482                         /*
 483                          * Received EOF or error.  They are treated
 484                          * similarly, except that an error message is printed
 485                          * if it was an error condition.
 486                          */
 487                         if (len < 0) {
 488                                 snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno));
 489                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 490                                 stderr_bytes += strlen(buf);
 491                         }
 492                         /* Mark that we have seen EOF. */
 493                         stdin_eof = 1;
 494                         /*
 495                          * Send an EOF message to the server unless there is
 496                          * data in the buffer.  If there is data in the
 497                          * buffer, no message will be sent now.  Code
 498                          * elsewhere will send the EOF when the buffer
 499                          * becomes empty if stdin_eof is set.
 500                          */
 501                         if (buffer_len(&stdin_buffer) == 0) {
 502                                 packet_start(SSH_CMSG_EOF);
 503                                 packet_send();
 504                         }
 505                 } else if (escape_char == -1) {
 506                         /*
 507                          * Normal successful read, and no escape character.
 508                          * Just append the data to buffer.
 509                          */
 510                         buffer_append(&stdin_buffer, buf, len);
 511                         stdin_bytes += len;
 512                 } else {
 513                         /*
 514                          * Normal, successful read.  But we have an escape character
 515                          * and have to process the characters one by one.
 516                          */
 517                         unsigned int i;
 518                         for (i = 0; i < len; i++) {
 519                                 unsigned char ch;
 520                                 /* Get one character at a time. */
 521                                 ch = buf[i];
 522
 523                                 if (escape_pending) {
 524                                         /* We have previously seen an escape character. */
 525                                         /* Clear the flag now. */
 526                                         escape_pending = 0;
 527                                         /* Process the escaped character. */
 528                                         switch (ch) {
 529                                         case '.':
 530                                                 /* Terminate the connection. */
 531                                                 snprintf(buf, sizeof buf, "%c.\r\n", escape_char);
 532                                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 533                                                 stderr_bytes += strlen(buf);
 534                                                 quit_pending = 1;
 535                                                 return;
 536
 537                                         case 'Z' - 64:
 538                                                 /* Suspend the program. */
 539                                                 /* Print a message to that effect to the user. */
 540                                                 snprintf(buf, sizeof buf, "%c^Z\r\n", escape_char);
 541                                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 542                                                 stderr_bytes += strlen(buf);
 543
 544                                                 /* Restore terminal modes and suspend. */
 545                                                 client_suspend_self();
 546
 547                                                 /* We have been continued. */
 548                                                 continue;
 549
 550                                         case '&':
 551                                                 /*
 552                                                  * Detach the program (continue to serve connections,
 553                                                  * but put in background and no more new connections).
 554                                                  */
 555                                                 if (!stdin_eof) {
 556                                                         /*
 557                                                          * Sending SSH_CMSG_EOF alone does not always appear
 558                                                          * to be enough.  So we try to send an EOF character
 559                                                          * first.
 560                                                          */
 561                                                         packet_start(SSH_CMSG_STDIN_DATA);
 562                                                         packet_put_string("\004", 1);
 563                                                         packet_send();
 564                                                         /* Close stdin. */
 565                                                         stdin_eof = 1;
 566                                                         if (buffer_len(&stdin_buffer) == 0) {
 567                                                                 packet_start(SSH_CMSG_EOF);
 568                                                                 packet_send();
 569                                                         }
 570                                                 }
 571                                                 /* Restore tty modes. */
 572                                                 leave_raw_mode();
 573
 574                                                 /* Stop listening for new connections. */
 575                                                 channel_stop_listening();
 576
 577                                                 printf("%c& [backgrounded]\n", escape_char);
 578
 579                                                 /* Fork into background. */
 580                                                 pid = fork();
 581                                                 if (pid < 0) {
 582                                                         error("fork: %.100s", strerror(errno));
 583                                                         continue;
 584                                                 }
 585                                                 if (pid != 0) { /* This is the parent. */
 586                                                         /* The parent just exits. */
 587                                                         exit(0);
 588                                                 }
 589                                                 /* The child continues serving connections. */
 590                                                 continue;
 591
 592                                         case '?':
 593                                                 snprintf(buf, sizeof buf,
 594 "%c?\r\n\
 595 Supported escape sequences:\r\n\
 596 ~.  - terminate connection\r\n\
 597 ~^Z - suspend ssh\r\n\
 598 ~#  - list forwarded connections\r\n\
 599 ~&  - background ssh (when waiting for connections to terminate)\r\n\
 600 ~?  - this message\r\n\
 601 ~~  - send the escape character by typing it twice\r\n\
 602 (Note that escapes are only recognized immediately after newline.)\r\n",
 603                                                          escape_char);
 604                                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 605                                                 continue;
 606
 607                                         case '#':
 608                                                 snprintf(buf, sizeof buf, "%c#\r\n", escape_char);
 609                                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 610                                                 s = channel_open_message();
 611                                                 buffer_append(&stderr_buffer, s, strlen(s));
 612                                                 xfree(s);
 613                                                 continue;
 614
 615                                         default:
 616                                                 if (ch != escape_char) {
 617                                                         /*
 618                                                          * Escape character followed by non-special character.
 619                                                          * Append both to the input buffer.
 620                                                          */
 621                                                         buf[0] = escape_char;
 622                                                         buf[1] = ch;
 623                                                         buffer_append(&stdin_buffer, buf, 2);
 624                                                         stdin_bytes += 2;
 625                                                         continue;
 626                                                 }
 627                                                 /*
 628                                                  * Note that escape character typed twice
 629                                                  * falls through here; the latter gets processed
 630                                                  * as a normal character below.
 631                                                  */
 632                                                 break;
 633                                         }
 634                                 } else {
 635                                         /*
 636                                          * The previous character was not an escape char. Check if this
 637                                          * is an escape.
 638                                          */
 639                                         if (last_was_cr && ch == escape_char) {
 640                                                 /* It is. Set the flag and continue to next character. */
 641                                                 escape_pending = 1;
 642                                                 continue;
 643                                         }
 644                                 }
 645
 646                                 /*
 647                                  * Normal character.  Record whether it was a newline,
 648                                  * and append it to the buffer.
 649                                  */
 650                                 last_was_cr = (ch == '\r' || ch == '\n');
 651                                 buf[0] = ch;
 652                                 buffer_append(&stdin_buffer, buf, 1);
 653                                 stdin_bytes += 1;
 654                                 continue;
 655                         }
 656                 }
 657         }
 658 }
 659
 660 void
 661 client_process_output(fd_set * writeset)
 662 {
 663         int len;
 664         char buf[100];
 665
 666         /* Write buffered output to stdout. */
 667         if (FD_ISSET(fileno(stdout), writeset)) {
 668                 /* Write as much data as possible. */
 669                 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
 670                     buffer_len(&stdout_buffer));
 671                 if (len <= 0) {
 672                         if (errno == EAGAIN)
 673                                 len = 0;
 674                         else {
 675                                 /*
 676                                  * An error or EOF was encountered.  Put an
 677                                  * error message to stderr buffer.
 678                                  */
 679                                 snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno));
 680                                 buffer_append(&stderr_buffer, buf, strlen(buf));
 681                                 stderr_bytes += strlen(buf);
 682                                 quit_pending = 1;
 683                                 return;
 684                         }
 685                 }
 686                 /* Consume printed data from the buffer. */
 687                 buffer_consume(&stdout_buffer, len);
 688         }
 689         /* Write buffered output to stderr. */
 690         if (FD_ISSET(fileno(stderr), writeset)) {
 691                 /* Write as much data as possible. */
 692                 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
 693                     buffer_len(&stderr_buffer));
 694                 if (len <= 0) {
 695                         if (errno == EAGAIN)
 696                                 len = 0;
 697                         else {
 698                                 /* EOF or error, but can't even print error message. */
 699                                 quit_pending = 1;
 700                                 return;
 701                         }
 702                 }
 703                 /* Consume printed characters from the buffer. */
 704                 buffer_consume(&stderr_buffer, len);
 705         }
 706 }
 707
 708 /*
 709  * Get packets from the connection input buffer, and process them as long as
 710  * there are packets available.
 711  *
 712  * Any unknown packets received during the actual
 713  * session cause the session to terminate.  This is
 714  * intended to make debugging easier since no
 715  * confirmations are sent.  Any compatible protocol
 716  * extensions must be negotiated during the
 717  * preparatory phase.
 718  */
 719
 720 void
 721 client_process_buffered_input_packets()
 722 {
 723         dispatch_run(DISPATCH_NONBLOCK, &quit_pending);
 724 }
 725
 726 /*
 727  * Implements the interactive session with the server.  This is called after
 728  * the user has been authenticated, and a command has been started on the
 729  * remote host.  If escape_char != -1, it is the character used as an escape
 730  * character for terminating or suspending the session.
 731  */
 732
 733 int
 734 client_loop(int have_pty, int escape_char_arg)
 735 {
 736         extern Options options;
 737         double start_time, total_time;
 738         int len;
 739         char buf[100];
 740
 741         debug("Entering interactive session.");
 742
 743         start_time = get_current_time();
 744
 745         /* Initialize variables. */
 746         escape_pending = 0;
 747         last_was_cr = 1;
 748         exit_status = -1;
 749         stdin_eof = 0;
 750         buffer_high = 64 * 1024;
 751         connection_in = packet_get_connection_in();
 752         connection_out = packet_get_connection_out();
 753         max_fd = connection_in;
 754         if (connection_out > max_fd)
 755                 max_fd = connection_out;
 756         stdin_bytes = 0;
 757         stdout_bytes = 0;
 758         stderr_bytes = 0;
 759         quit_pending = 0;
 760         escape_char = escape_char_arg;
 761
 762         /* Initialize buffers. */
 763         buffer_init(&stdin_buffer);
 764         buffer_init(&stdout_buffer);
 765         buffer_init(&stderr_buffer);
 766
 767         client_init_dispatch();
 768
 769         /* Set signal handlers to restore non-blocking mode.  */
 770         signal(SIGINT, signal_handler);
 771         signal(SIGQUIT, signal_handler);
 772         signal(SIGTERM, signal_handler);
 773         signal(SIGPIPE, SIG_IGN);
 774         if (have_pty)
 775                 signal(SIGWINCH, window_change_handler);
 776
 777         if (have_pty)
 778                 enter_raw_mode();
 779
 780         /* Check if we should immediately send of on stdin. */
 781         if (!compat20)
 782                 client_check_initial_eof_on_stdin();
 783
 784         /* Main loop of the client for the interactive session mode. */
 785         while (!quit_pending) {
 786                 fd_set readset, writeset;
 787
 788                 /* Process buffered packets sent by the server. */
 789                 client_process_buffered_input_packets();
 790
 791                 if (compat20 && !channel_still_open()) {
 792                         debug("!channel_still_open.");
 793                         break;
 794                 }
 795
 796                 /*
 797                  * Make packets of buffered stdin data, and buffer them for
 798                  * sending to the server.
 799                  */
 800                 if (!compat20)
 801                         client_make_packets_from_stdin_data();
 802
 803                 /*
 804                  * Make packets from buffered channel data, and buffer them
 805                  * for sending to the server.
 806                  */
 807                 if (packet_not_very_much_data_to_write())
 808                         channel_output_poll();
 809
 810                 /*
 811                  * Check if the window size has changed, and buffer a message
 812                  * about it to the server if so.
 813                  */
 814                 client_check_window_change();
 815
 816                 if (quit_pending)
 817                         break;
 818
 819                 /*
 820                  * Wait until we have something to do (something becomes
 821                  * available on one of the descriptors).
 822                  */
 823                 client_wait_until_can_do_something(&readset, &writeset);
 824
 825                 if (quit_pending)
 826                         break;
 827
 828                 /* Do channel operations. */
 829                 channel_after_select(&readset, &writeset);
 830
 831                 /* Buffer input from the connection.  */
 832                 client_process_net_input(&readset);
 833
 834                 if (quit_pending)
 835                         break;
 836
 837                 if (!compat20) {
 838                         /* Buffer data from stdin */
 839                         client_process_input(&readset);
 840                         /*
 841                          * Process output to stdout and stderr.  Output to
 842                          * the connection is processed elsewhere (above).
 843                          */
 844                         client_process_output(&writeset);
 845                 }
 846
 847                 /* Send as much buffered packet data as possible to the sender. */
 848                 if (FD_ISSET(connection_out, &writeset))
 849                         packet_write_poll();
 850         }
 851
 852         /* Terminate the session. */
 853
 854         /* Stop watching for window change. */
 855         if (have_pty)
 856                 signal(SIGWINCH, SIG_DFL);
 857
 858         /* Stop listening for connections. */
 859         channel_stop_listening();
 860
 861         /*
 862          * In interactive mode (with pseudo tty) display a message indicating
 863          * that the connection has been closed.
 864          */
 865         if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
 866                 snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host);
 867                 buffer_append(&stderr_buffer, buf, strlen(buf));
 868                 stderr_bytes += strlen(buf);
 869         }
 870         /* Output any buffered data for stdout. */
 871         while (buffer_len(&stdout_buffer) > 0) {
 872                 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
 873                     buffer_len(&stdout_buffer));
 874                 if (len <= 0) {
 875                         error("Write failed flushing stdout buffer.");
 876                         break;
 877                 }
 878                 buffer_consume(&stdout_buffer, len);
 879         }
 880
 881         /* Output any buffered data for stderr. */
 882         while (buffer_len(&stderr_buffer) > 0) {
 883                 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
 884                     buffer_len(&stderr_buffer));
 885                 if (len <= 0) {
 886                         error("Write failed flushing stderr buffer.");
 887                         break;
 888                 }
 889                 buffer_consume(&stderr_buffer, len);
 890         }
 891
 892         if (have_pty)
 893                 leave_raw_mode();
 894
 895         /* Clear and free any buffers. */
 896         memset(buf, 0, sizeof(buf));
 897         buffer_free(&stdin_buffer);
 898         buffer_free(&stdout_buffer);
 899         buffer_free(&stderr_buffer);
 900
 901         /* Report bytes transferred, and transfer rates. */
 902         total_time = get_current_time() - start_time;
 903         debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
 904               stdin_bytes, stdout_bytes, stderr_bytes, total_time);
 905         if (total_time > 0)
 906                 debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
 907                       stdin_bytes / total_time, stdout_bytes / total_time,
 908                       stderr_bytes / total_time);
 909
 910         /* Return the exit status of the program. */
 911         debug("Exit status %d", exit_status);
 912         return exit_status;
 913 }
 914
 915 /*********/
 916
 917 void
 918 client_input_stdout_data(int type, int plen)
 919 {
 920         unsigned int data_len;
 921         char *data = packet_get_string(&data_len);
 922         packet_integrity_check(plen, 4 + data_len, type);
 923         buffer_append(&stdout_buffer, data, data_len);
 924         stdout_bytes += data_len;
 925         memset(data, 0, data_len);
 926         xfree(data);
 927 }
 928 void
 929 client_input_stderr_data(int type, int plen)
 930 {
 931         unsigned int data_len;
 932         char *data = packet_get_string(&data_len);
 933         packet_integrity_check(plen, 4 + data_len, type);
 934         buffer_append(&stderr_buffer, data, data_len);
 935         stdout_bytes += data_len;
 936         memset(data, 0, data_len);
 937         xfree(data);
 938 }
 939 void
 940 client_input_exit_status(int type, int plen)
 941 {
 942         packet_integrity_check(plen, 4, type);
 943         exit_status = packet_get_int();
 944         /* Acknowledge the exit. */
 945         packet_start(SSH_CMSG_EXIT_CONFIRMATION);
 946         packet_send();
 947         /*
 948          * Must wait for packet to be sent since we are
 949          * exiting the loop.
 950          */
 951         packet_write_wait();
 952         /* Flag that we want to exit. */
 953         quit_pending = 1;
 954 }
 955
 956 void
 957 client_init_dispatch_20()
 958 {
 959         dispatch_init(&dispatch_protocol_error);
 960         dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
 961         dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
 962         dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
 963         dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
 964         dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
 965         dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
 966         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
 967         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
 968 }
 969 void
 970 client_init_dispatch_13()
 971 {
 972         dispatch_init(NULL);
 973         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
 974         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
 975         dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
 976         dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
 977         dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
 978         dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
 979         dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
 980         dispatch_set(SSH_SMSG_AGENT_OPEN, &auth_input_open_request);
 981         dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
 982         dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
 983         dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);
 984         dispatch_set(SSH_SMSG_X11_OPEN, &x11_input_open);
 985 }
 986 void
 987 client_init_dispatch_15()
 988 {
 989         client_init_dispatch_13();
 990         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
 991         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
 992 }
 993 void
 994 client_init_dispatch()
 995 {
 996         if (compat20)
 997                 client_init_dispatch_20();
 998         else if (compat13)
 999                 client_init_dispatch_13();
1000         else
1001                 client_init_dispatch_15();
1002 }
1003
1004 void
1005 client_input_channel_req(int id, void *arg)
1006 {
1007         Channel *c = NULL;
1008         unsigned int len;
1009         int success = 0;
1010         int reply;
1011         char *rtype;
1012
1013         rtype = packet_get_string(&len);
1014         reply = packet_get_char();
1015
1016         log("session_input_channel_req: rtype %s reply %d", rtype, reply);
1017
1018         c = channel_lookup(id);
1019         if (c == NULL)
1020                 fatal("session_input_channel_req: channel %d: bad channel", id);
1021
1022         if (session_ident == -1) {
1023                 error("client_input_channel_req: no channel %d", id);
1024         } else if (id != session_ident) {
1025                 error("client_input_channel_req: bad channel %d != %d",
1026                     id, session_ident);
1027         } else if (strcmp(rtype, "exit-status") == 0) {
1028                 success = 1;
1029                 exit_status = packet_get_int();
1030         }
1031         if (reply) {
1032                 packet_start(success ?
1033                     SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1034                 packet_put_int(c->remote_id);
1035                 packet_send();
1036         }
1037         xfree(rtype);
1038 }
1039
1040 void
1041 client_set_session_ident(int id)
1042 {
1043         debug("client_set_session_ident: id %d", id);
1044         session_ident = id;
1045         channel_register_callback(id, SSH2_MSG_CHANNEL_REQUEST,
1046             client_input_channel_req, (void *)0);
1047 }