1/*
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 * The main loop for the interactive session (client side).
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 *
13 *
14 * Copyright (c) 1999 Theo de Raadt. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 *
36 *
37 * SSH2 support added by Markus Friedl.
38 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved.
39 *
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
42 * are met:
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
50 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
51 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
52 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
53 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
54 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
55 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
56 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
57 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
58 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
59 */
60
61#include "includes.h"
62RCSID("$OpenBSD: clientloop.c,v 1.112 2003/06/28 16:23:06 deraadt Exp $");
63
64#include "ssh.h"
65#include "ssh1.h"
66#include "ssh2.h"
67#include "xmalloc.h"
68#include "packet.h"
69#include "buffer.h"
70#include "compat.h"
71#include "channels.h"
72#include "dispatch.h"
73#include "buffer.h"
74#include "bufaux.h"
75#include "key.h"
76#include "kex.h"
77#include "log.h"
78#include "readconf.h"
79#include "clientloop.h"
80#include "authfd.h"
81#include "atomicio.h"
82#include "sshtty.h"
83#include "misc.h"
84#include "readpass.h"
85
86/* import options */
87extern Options options;
88
89/* Flag indicating that stdin should be redirected from /dev/null. */
90extern int stdin_null_flag;
91
92/*
93 * Name of the host we are connecting to. This is the name given on the
94 * command line, or the HostName specified for the user-supplied name in a
95 * configuration file.
96 */
97extern char *host;
98
99/*
100 * Flag to indicate that we have received a window change signal which has
101 * not yet been processed. This will cause a message indicating the new
102 * window size to be sent to the server a little later. This is volatile
103 * because this is updated in a signal handler.
104 */
105static volatile sig_atomic_t received_window_change_signal = 0;
106static volatile sig_atomic_t received_signal = 0;
107
108/* Flag indicating whether the user\'s terminal is in non-blocking mode. */
109static int in_non_blocking_mode = 0;
110
111/* Common data for the client loop code. */
112static int quit_pending; /* Set to non-zero to quit the client loop. */
113static int escape_char; /* Escape character. */
114static int escape_pending; /* Last character was the escape character */
115static int last_was_cr; /* Last character was a newline. */
116static int exit_status; /* Used to store the exit status of the command. */
117static int stdin_eof; /* EOF has been encountered on standard error. */
118static Buffer stdin_buffer; /* Buffer for stdin data. */
119static Buffer stdout_buffer; /* Buffer for stdout data. */
120static Buffer stderr_buffer; /* Buffer for stderr data. */
121static u_long stdin_bytes, stdout_bytes, stderr_bytes;
122static u_int buffer_high;/* Soft max buffer size. */
123static int connection_in; /* Connection to server (input). */
124static int connection_out; /* Connection to server (output). */
125static int need_rekeying; /* Set to non-zero if rekeying is requested. */
126static int session_closed = 0; /* In SSH2: login session closed. */
127
128static void client_init_dispatch(void);
129int session_ident = -1;
130
131/*XXX*/
132extern Kex *xxx_kex;
133
134/* Restores stdin to blocking mode. */
135
136static void
137leave_non_blocking(void)
138{
139 if (in_non_blocking_mode) {
140 (void) fcntl(fileno(stdin), F_SETFL, 0);
141 in_non_blocking_mode = 0;
142 fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
143 }
144}
145
146/* Puts stdin terminal in non-blocking mode. */
147
148static void
149enter_non_blocking(void)
150{
151 in_non_blocking_mode = 1;
152 (void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
153 fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
154}
155
156/*
157 * Signal handler for the window change signal (SIGWINCH). This just sets a
158 * flag indicating that the window has changed.
159 */
160
161static void
162window_change_handler(int sig)
163{
164 received_window_change_signal = 1;
165 signal(SIGWINCH, window_change_handler);
166}
167
168/*
169 * Signal handler for signals that cause the program to terminate. These
170 * signals must be trapped to restore terminal modes.
171 */
172
173static void
174signal_handler(int sig)
175{
176 received_signal = sig;
177 quit_pending = 1;
178}
179
180/*
181 * Returns current time in seconds from Jan 1, 1970 with the maximum
182 * available resolution.
183 */
184
185static double
186get_current_time(void)
187{
188 struct timeval tv;
189 gettimeofday(&tv, NULL);
190 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
191}
192
193/*
194 * This is called when the interactive is entered. This checks if there is
195 * an EOF coming on stdin. We must check this explicitly, as select() does
196 * not appear to wake up when redirecting from /dev/null.
197 */
198
199static void
200client_check_initial_eof_on_stdin(void)
201{
202 int len;
203 char buf[1];
204
205 /*
206 * If standard input is to be "redirected from /dev/null", we simply
207 * mark that we have seen an EOF and send an EOF message to the
208 * server. Otherwise, we try to read a single character; it appears
209 * that for some files, such /dev/null, select() never wakes up for
210 * read for this descriptor, which means that we never get EOF. This
211 * way we will get the EOF if stdin comes from /dev/null or similar.
212 */
213 if (stdin_null_flag) {
214 /* Fake EOF on stdin. */
215 debug("Sending eof.");
216 stdin_eof = 1;
217 packet_start(SSH_CMSG_EOF);
218 packet_send();
219 } else {
220 enter_non_blocking();
221
222 /* Check for immediate EOF on stdin. */
223 len = read(fileno(stdin), buf, 1);
224 if (len == 0) {
225 /* EOF. Record that we have seen it and send EOF to server. */
226 debug("Sending eof.");
227 stdin_eof = 1;
228 packet_start(SSH_CMSG_EOF);
229 packet_send();
230 } else if (len > 0) {
231 /*
232 * Got data. We must store the data in the buffer,
233 * and also process it as an escape character if
234 * appropriate.
235 */
236 if ((u_char) buf[0] == escape_char)
237 escape_pending = 1;
238 else
239 buffer_append(&stdin_buffer, buf, 1);
240 }
241 leave_non_blocking();
242 }
243}
244
245
246/*
247 * Make packets from buffered stdin data, and buffer them for sending to the
248 * connection.
249 */
250
251static void
252client_make_packets_from_stdin_data(void)
253{
254 u_int len;
255
256 /* Send buffered stdin data to the server. */
257 while (buffer_len(&stdin_buffer) > 0 &&
258 packet_not_very_much_data_to_write()) {
259 len = buffer_len(&stdin_buffer);
260 /* Keep the packets at reasonable size. */
261 if (len > packet_get_maxsize())
262 len = packet_get_maxsize();
263 packet_start(SSH_CMSG_STDIN_DATA);
264 packet_put_string(buffer_ptr(&stdin_buffer), len);
265 packet_send();
266 buffer_consume(&stdin_buffer, len);
267 stdin_bytes += len;
268 /* If we have a pending EOF, send it now. */
269 if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
270 packet_start(SSH_CMSG_EOF);
271 packet_send();
272 }
273 }
274}
275
276/*
277 * Checks if the client window has changed, and sends a packet about it to
278 * the server if so. The actual change is detected elsewhere (by a software
279 * interrupt on Unix); this just checks the flag and sends a message if
280 * appropriate.
281 */
282
283static void
284client_check_window_change(void)
285{
286 struct winsize ws;
287
288 if (! received_window_change_signal)
289 return;
290 /** XXX race */
291 received_window_change_signal = 0;
292
293 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
294 return;
295
296 debug2("client_check_window_change: changed");
297
298 if (compat20) {
299 channel_request_start(session_ident, "window-change", 0);
300 packet_put_int(ws.ws_col);
301 packet_put_int(ws.ws_row);
302 packet_put_int(ws.ws_xpixel);
303 packet_put_int(ws.ws_ypixel);
304 packet_send();
305 } else {
306 packet_start(SSH_CMSG_WINDOW_SIZE);
307 packet_put_int(ws.ws_row);
308 packet_put_int(ws.ws_col);
309 packet_put_int(ws.ws_xpixel);
310 packet_put_int(ws.ws_ypixel);
311 packet_send();
312 }
313}
314
315/*
316 * Waits until the client can do something (some data becomes available on
317 * one of the file descriptors).
318 */
319
320static void
321client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
322 int *maxfdp, int *nallocp, int rekeying)
323{
324 /* Add any selections by the channel mechanism. */
325 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, rekeying);
326
327 if (!compat20) {
328 /* Read from the connection, unless our buffers are full. */
329 if (buffer_len(&stdout_buffer) < buffer_high &&
330 buffer_len(&stderr_buffer) < buffer_high &&
331 channel_not_very_much_buffered_data())
332 FD_SET(connection_in, *readsetp);
333 /*
334 * Read from stdin, unless we have seen EOF or have very much
335 * buffered data to send to the server.
336 */
337 if (!stdin_eof && packet_not_very_much_data_to_write())
338 FD_SET(fileno(stdin), *readsetp);
339
340 /* Select stdout/stderr if have data in buffer. */
341 if (buffer_len(&stdout_buffer) > 0)
342 FD_SET(fileno(stdout), *writesetp);
343 if (buffer_len(&stderr_buffer) > 0)
344 FD_SET(fileno(stderr), *writesetp);
345 } else {
346 /* channel_prepare_select could have closed the last channel */
347 if (session_closed && !channel_still_open() &&
348 !packet_have_data_to_write()) {
349 /* clear mask since we did not call select() */
350 memset(*readsetp, 0, *nallocp);
351 memset(*writesetp, 0, *nallocp);
352 return;
353 } else {
354 FD_SET(connection_in, *readsetp);
355 }
356 }
357
358 /* Select server connection if have data to write to the server. */
359 if (packet_have_data_to_write())
360 FD_SET(connection_out, *writesetp);
361
362 /*
363 * Wait for something to happen. This will suspend the process until
364 * some selected descriptor can be read, written, or has some other
365 * event pending. Note: if you want to implement SSH_MSG_IGNORE
366 * messages to fool traffic analysis, this might be the place to do
367 * it: just have a random timeout for the select, and send a random
368 * SSH_MSG_IGNORE packet when the timeout expires.
369 */
370
371 if (select((*maxfdp)+1, *readsetp, *writesetp, NULL, NULL) < 0) {
372 char buf[100];
373
374 /*
375 * We have to clear the select masks, because we return.
376 * We have to return, because the mainloop checks for the flags
377 * set by the signal handlers.
378 */
379 memset(*readsetp, 0, *nallocp);
380 memset(*writesetp, 0, *nallocp);
381
382 if (errno == EINTR)
383 return;
384 /* Note: we might still have data in the buffers. */
385 snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
386 buffer_append(&stderr_buffer, buf, strlen(buf));
387 quit_pending = 1;
388 }
389}
390
391static void
392client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
393{
394 struct winsize oldws, newws;
395
396 /* Flush stdout and stderr buffers. */
397 if (buffer_len(bout) > 0)
398 atomicio(vwrite, fileno(stdout), buffer_ptr(bout), buffer_len(bout));
399 if (buffer_len(berr) > 0)
400 atomicio(vwrite, fileno(stderr), buffer_ptr(berr), buffer_len(berr));
401
402 leave_raw_mode();
403
404 /*
405 * Free (and clear) the buffer to reduce the amount of data that gets
406 * written to swap.
407 */
408 buffer_free(bin);
409 buffer_free(bout);
410 buffer_free(berr);
411
412 /* Save old window size. */
413 ioctl(fileno(stdin), TIOCGWINSZ, &oldws);
414
415 /* Send the suspend signal to the program itself. */
416 kill(getpid(), SIGTSTP);
417
418 /* Check if the window size has changed. */
419 if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
420 (oldws.ws_row != newws.ws_row ||
421 oldws.ws_col != newws.ws_col ||
422 oldws.ws_xpixel != newws.ws_xpixel ||
423 oldws.ws_ypixel != newws.ws_ypixel))
424 received_window_change_signal = 1;
425
426 /* OK, we have been continued by the user. Reinitialize buffers. */
427 buffer_init(bin);
428 buffer_init(bout);
429 buffer_init(berr);
430
431 enter_raw_mode();
432}
433
434static void
435client_process_net_input(fd_set * readset)
436{
437 int len;
438 char buf[8192];
439
440 /*
441 * Read input from the server, and add any such data to the buffer of
442 * the packet subsystem.
443 */
444 if (FD_ISSET(connection_in, readset)) {
445 /* Read as much as possible. */
446 len = read(connection_in, buf, sizeof(buf));
447 if (len == 0) {
448 /* Received EOF. The remote host has closed the connection. */
449 snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n",
450 host);
451 buffer_append(&stderr_buffer, buf, strlen(buf));
452 quit_pending = 1;
453 return;
454 }
455 /*
456 * There is a kernel bug on Solaris that causes select to
457 * sometimes wake up even though there is no data available.
458 */
459 if (len < 0 && (errno == EAGAIN || errno == EINTR))
460 len = 0;
461
462 if (len < 0) {
463 /* An error has encountered. Perhaps there is a network problem. */
464 snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n",
465 host, strerror(errno));
466 buffer_append(&stderr_buffer, buf, strlen(buf));
467 quit_pending = 1;
468 return;
469 }
470 packet_process_incoming(buf, len);
471 }
472}
473
474static void
475process_cmdline(void)
476{
477 void (*handler)(int);
478 char *s, *cmd;
479 u_short fwd_port, fwd_host_port;
480 char buf[1024], sfwd_port[6], sfwd_host_port[6];
481 int local = 0;
482
483 leave_raw_mode();
484 handler = signal(SIGINT, SIG_IGN);
485 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
486 if (s == NULL)
487 goto out;
488 while (*s && isspace(*s))
489 s++;
490 if (*s == 0)
491 goto out;
492 if (strlen(s) < 2 || s[0] != '-' || !(s[1] == 'L' || s[1] == 'R')) {
493 logit("Invalid command.");
494 goto out;
495 }
496 if (s[1] == 'L')
497 local = 1;
498 if (!local && !compat20) {
499 logit("Not supported for SSH protocol version 1.");
500 goto out;
501 }
502 s += 2;
503 while (*s && isspace(*s))
504 s++;
505
506 if (sscanf(s, "%5[0-9]:%255[^:]:%5[0-9]",
507 sfwd_port, buf, sfwd_host_port) != 3 &&
508 sscanf(s, "%5[0-9]/%255[^/]/%5[0-9]",
509 sfwd_port, buf, sfwd_host_port) != 3) {
510 logit("Bad forwarding specification.");
511 goto out;
512 }
513 if ((fwd_port = a2port(sfwd_port)) == 0 ||
514 (fwd_host_port = a2port(sfwd_host_port)) == 0) {
515 logit("Bad forwarding port(s).");
516 goto out;
517 }
518 if (local) {
519 if (channel_setup_local_fwd_listener(fwd_port, buf,
520 fwd_host_port, options.gateway_ports) < 0) {
521 logit("Port forwarding failed.");
522 goto out;
523 }
524 } else
525 channel_request_remote_forwarding(fwd_port, buf,
526 fwd_host_port);
527 logit("Forwarding port.");
528out:
529 signal(SIGINT, handler);
530 enter_raw_mode();
531 if (cmd)
532 xfree(cmd);
533}
534
535/* process the characters one by one */
536static int
537process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
538{
539 char string[1024];
540 pid_t pid;
541 int bytes = 0;
542 u_int i;
543 u_char ch;
544 char *s;
545
546 for (i = 0; i < len; i++) {
547 /* Get one character at a time. */
548 ch = buf[i];
549
550 if (escape_pending) {
551 /* We have previously seen an escape character. */
552 /* Clear the flag now. */
553 escape_pending = 0;
554
555 /* Process the escaped character. */
556 switch (ch) {
557 case '.':
558 /* Terminate the connection. */
559 snprintf(string, sizeof string, "%c.\r\n", escape_char);
560 buffer_append(berr, string, strlen(string));
561
562 quit_pending = 1;
563 return -1;
564
565 case 'Z' - 64:
566 /* Suspend the program. */
567 /* Print a message to that effect to the user. */
568 snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
569 buffer_append(berr, string, strlen(string));
570
571 /* Restore terminal modes and suspend. */
572 client_suspend_self(bin, bout, berr);
573
574 /* We have been continued. */
575 continue;
576
577 case 'B':
578 if (compat20) {
579 snprintf(string, sizeof string,
580 "%cB\r\n", escape_char);
581 buffer_append(berr, string,
582 strlen(string));
583 channel_request_start(session_ident,
584 "break", 0);
585 packet_put_int(1000);
586 packet_send();
587 }
588 continue;
589
590 case 'R':
591 if (compat20) {
592 if (datafellows & SSH_BUG_NOREKEY)
593 logit("Server does not support re-keying");
594 else
595 need_rekeying = 1;
596 }
597 continue;
598
599 case '&':
600 /*
601 * Detach the program (continue to serve connections,
602 * but put in background and no more new connections).
603 */
604 /* Restore tty modes. */
605 leave_raw_mode();
606
607 /* Stop listening for new connections. */
608 channel_stop_listening();
609
610 snprintf(string, sizeof string,
611 "%c& [backgrounded]\n", escape_char);
612 buffer_append(berr, string, strlen(string));
613
614 /* Fork into background. */
615 pid = fork();
616 if (pid < 0) {
617 error("fork: %.100s", strerror(errno));
618 continue;
619 }
620 if (pid != 0) { /* This is the parent. */
621 /* The parent just exits. */
622 exit(0);
623 }
624 /* The child continues serving connections. */
625 if (compat20) {
626 buffer_append(bin, "\004", 1);
627 /* fake EOF on stdin */
628 return -1;
629 } else if (!stdin_eof) {
630 /*
631 * Sending SSH_CMSG_EOF alone does not always appear
632 * to be enough. So we try to send an EOF character
633 * first.
634 */
635 packet_start(SSH_CMSG_STDIN_DATA);
636 packet_put_string("\004", 1);
637 packet_send();
638 /* Close stdin. */
639 stdin_eof = 1;
640 if (buffer_len(bin) == 0) {
641 packet_start(SSH_CMSG_EOF);
642 packet_send();
643 }
644 }
645 continue;
646
647 case '?':
648 snprintf(string, sizeof string,
649"%c?\r\n\
650Supported escape sequences:\r\n\
651%c. - terminate connection\r\n\
652%cB - send a BREAK to the remote system\r\n\
653%cC - open a command line\r\n\
654%cR - Request rekey (SSH protocol 2 only)\r\n\
655%c^Z - suspend ssh\r\n\
656%c# - list forwarded connections\r\n\
657%c& - background ssh (when waiting for connections to terminate)\r\n\
658%c? - this message\r\n\
659%c%c - send the escape character by typing it twice\r\n\
660(Note that escapes are only recognized immediately after newline.)\r\n",
661 escape_char, escape_char, escape_char, escape_char,
662 escape_char, escape_char, escape_char, escape_char,
663 escape_char, escape_char, escape_char);
664 buffer_append(berr, string, strlen(string));
665 continue;
666
667 case '#':
668 snprintf(string, sizeof string, "%c#\r\n", escape_char);
669 buffer_append(berr, string, strlen(string));
670 s = channel_open_message();
671 buffer_append(berr, s, strlen(s));
672 xfree(s);
673 continue;
674
675 case 'C':
676 process_cmdline();
677 continue;
678
679 default:
680 if (ch != escape_char) {
681 buffer_put_char(bin, escape_char);
682 bytes++;
683 }
684 /* Escaped characters fall through here */
685 break;
686 }
687 } else {
688 /*
689 * The previous character was not an escape char. Check if this
690 * is an escape.
691 */
692 if (last_was_cr && ch == escape_char) {
693 /* It is. Set the flag and continue to next character. */
694 escape_pending = 1;
695 continue;
696 }
697 }
698
699 /*
700 * Normal character. Record whether it was a newline,
701 * and append it to the buffer.
702 */
703 last_was_cr = (ch == '\r' || ch == '\n');
704 buffer_put_char(bin, ch);
705 bytes++;
706 }
707 return bytes;
708}
709
710static void
711client_process_input(fd_set * readset)
712{
713 int len;
714 char buf[8192];
715
716 /* Read input from stdin. */
717 if (FD_ISSET(fileno(stdin), readset)) {
718 /* Read as much as possible. */
719 len = read(fileno(stdin), buf, sizeof(buf));
720 if (len < 0 && (errno == EAGAIN || errno == EINTR))
721 return; /* we'll try again later */
722 if (len <= 0) {
723 /*
724 * Received EOF or error. They are treated
725 * similarly, except that an error message is printed
726 * if it was an error condition.
727 */
728 if (len < 0) {
729 snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno));
730 buffer_append(&stderr_buffer, buf, strlen(buf));
731 }
732 /* Mark that we have seen EOF. */
733 stdin_eof = 1;
734 /*
735 * Send an EOF message to the server unless there is
736 * data in the buffer. If there is data in the
737 * buffer, no message will be sent now. Code
738 * elsewhere will send the EOF when the buffer
739 * becomes empty if stdin_eof is set.
740 */
741 if (buffer_len(&stdin_buffer) == 0) {
742 packet_start(SSH_CMSG_EOF);
743 packet_send();
744 }
745 } else if (escape_char == SSH_ESCAPECHAR_NONE) {
746 /*
747 * Normal successful read, and no escape character.
748 * Just append the data to buffer.
749 */
750 buffer_append(&stdin_buffer, buf, len);
751 } else {
752 /*
753 * Normal, successful read. But we have an escape character
754 * and have to process the characters one by one.
755 */
756 if (process_escapes(&stdin_buffer, &stdout_buffer,
757 &stderr_buffer, buf, len) == -1)
758 return;
759 }
760 }
761}
762
763static void
764client_process_output(fd_set * writeset)
765{
766 int len;
767 char buf[100];
768
769 /* Write buffered output to stdout. */
770 if (FD_ISSET(fileno(stdout), writeset)) {
771 /* Write as much data as possible. */
772 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
773 buffer_len(&stdout_buffer));
774 if (len <= 0) {
775 if (errno == EINTR || errno == EAGAIN)
776 len = 0;
777 else {
778 /*
779 * An error or EOF was encountered. Put an
780 * error message to stderr buffer.
781 */
782 snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno));
783 buffer_append(&stderr_buffer, buf, strlen(buf));
784 quit_pending = 1;
785 return;
786 }
787 }
788 /* Consume printed data from the buffer. */
789 buffer_consume(&stdout_buffer, len);
790 stdout_bytes += len;
791 }
792 /* Write buffered output to stderr. */
793 if (FD_ISSET(fileno(stderr), writeset)) {
794 /* Write as much data as possible. */
795 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
796 buffer_len(&stderr_buffer));
797 if (len <= 0) {
798 if (errno == EINTR || errno == EAGAIN)
799 len = 0;
800 else {
801 /* EOF or error, but can't even print error message. */
802 quit_pending = 1;
803 return;
804 }
805 }
806 /* Consume printed characters from the buffer. */
807 buffer_consume(&stderr_buffer, len);
808 stderr_bytes += len;
809 }
810}
811
812/*
813 * Get packets from the connection input buffer, and process them as long as
814 * there are packets available.
815 *
816 * Any unknown packets received during the actual
817 * session cause the session to terminate. This is
818 * intended to make debugging easier since no
819 * confirmations are sent. Any compatible protocol
820 * extensions must be negotiated during the
821 * preparatory phase.
822 */
823
824static void
825client_process_buffered_input_packets(void)
826{
827 dispatch_run(DISPATCH_NONBLOCK, &quit_pending, compat20 ? xxx_kex : NULL);
828}
829
830/* scan buf[] for '~' before sending data to the peer */
831
832static int
833simple_escape_filter(Channel *c, char *buf, int len)
834{
835 /* XXX we assume c->extended is writeable */
836 return process_escapes(&c->input, &c->output, &c->extended, buf, len);
837}
838
839static void
840client_channel_closed(int id, void *arg)
841{
842 if (id != session_ident)
843 error("client_channel_closed: id %d != session_ident %d",
844 id, session_ident);
845 channel_cancel_cleanup(id);
846 session_closed = 1;
847 if (in_raw_mode())
848 leave_raw_mode();
849}
850
851/*
852 * Implements the interactive session with the server. This is called after
853 * the user has been authenticated, and a command has been started on the
854 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character
855 * used as an escape character for terminating or suspending the session.
856 */
857
858int
859client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
860{
861 fd_set *readset = NULL, *writeset = NULL;
862 double start_time, total_time;
863 int max_fd = 0, max_fd2 = 0, len, rekeying = 0, nalloc = 0;
864 char buf[100];
865
866 debug("Entering interactive session.");
867
868 start_time = get_current_time();
869
870 /* Initialize variables. */
871 escape_pending = 0;
872 last_was_cr = 1;
873 exit_status = -1;
874 stdin_eof = 0;
875 buffer_high = 64 * 1024;
876 connection_in = packet_get_connection_in();
877 connection_out = packet_get_connection_out();
878 max_fd = MAX(connection_in, connection_out);
879
880 if (!compat20) {
881 /* enable nonblocking unless tty */
882 if (!isatty(fileno(stdin)))
883 set_nonblock(fileno(stdin));
884 if (!isatty(fileno(stdout)))
885 set_nonblock(fileno(stdout));
886 if (!isatty(fileno(stderr)))
887 set_nonblock(fileno(stderr));
888 max_fd = MAX(max_fd, fileno(stdin));
889 max_fd = MAX(max_fd, fileno(stdout));
890 max_fd = MAX(max_fd, fileno(stderr));
891 }
892 stdin_bytes = 0;
893 stdout_bytes = 0;
894 stderr_bytes = 0;
895 quit_pending = 0;
896 escape_char = escape_char_arg;
897
898 /* Initialize buffers. */
899 buffer_init(&stdin_buffer);
900 buffer_init(&stdout_buffer);
901 buffer_init(&stderr_buffer);
902
903 client_init_dispatch();
904
905 /*
906 * Set signal handlers, (e.g. to restore non-blocking mode)
907 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
908 */
909 if (signal(SIGINT, SIG_IGN) != SIG_IGN)
910 signal(SIGINT, signal_handler);
911 if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
912 signal(SIGQUIT, signal_handler);
913 if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
914 signal(SIGTERM, signal_handler);
915 if (have_pty)
916 signal(SIGWINCH, window_change_handler);
917
918 if (have_pty)
919 enter_raw_mode();
920
921 if (compat20) {
922 session_ident = ssh2_chan_id;
923 if (escape_char != SSH_ESCAPECHAR_NONE)
924 channel_register_filter(session_ident,
925 simple_escape_filter);
926 if (session_ident != -1)
927 channel_register_cleanup(session_ident,
928 client_channel_closed);
929 } else {
930 /* Check if we should immediately send eof on stdin. */
931 client_check_initial_eof_on_stdin();
932 }
933
934 /* Main loop of the client for the interactive session mode. */
935 while (!quit_pending) {
936
937 /* Process buffered packets sent by the server. */
938 client_process_buffered_input_packets();
939
940 if (compat20 && session_closed && !channel_still_open())
941 break;
942
943 rekeying = (xxx_kex != NULL && !xxx_kex->done);
944
945 if (rekeying) {
946 debug("rekeying in progress");
947 } else {
948 /*
949 * Make packets of buffered stdin data, and buffer
950 * them for sending to the server.
951 */
952 if (!compat20)
953 client_make_packets_from_stdin_data();
954
955 /*
956 * Make packets from buffered channel data, and
957 * enqueue them for sending to the server.
958 */
959 if (packet_not_very_much_data_to_write())
960 channel_output_poll();
961
962 /*
963 * Check if the window size has changed, and buffer a
964 * message about it to the server if so.
965 */
966 client_check_window_change();
967
968 if (quit_pending)
969 break;
970 }
971 /*
972 * Wait until we have something to do (something becomes
973 * available on one of the descriptors).
974 */
975 max_fd2 = max_fd;
976 client_wait_until_can_do_something(&readset, &writeset,
977 &max_fd2, &nalloc, rekeying);
978
979 if (quit_pending)
980 break;
981
982 /* Do channel operations unless rekeying in progress. */
983 if (!rekeying) {
984 channel_after_select(readset, writeset);
985 if (need_rekeying || packet_need_rekeying()) {
986 debug("need rekeying");
987 xxx_kex->done = 0;
988 kex_send_kexinit(xxx_kex);
989 need_rekeying = 0;
990 }
991 }
992
993 /* Buffer input from the connection. */
994 client_process_net_input(readset);
995
996 if (quit_pending)
997 break;
998
999 if (!compat20) {
1000 /* Buffer data from stdin */
1001 client_process_input(readset);
1002 /*
1003 * Process output to stdout and stderr. Output to
1004 * the connection is processed elsewhere (above).
1005 */
1006 client_process_output(writeset);
1007 }
1008
1009 /* Send as much buffered packet data as possible to the sender. */
1010 if (FD_ISSET(connection_out, writeset))
1011 packet_write_poll();
1012 }
1013 if (readset)
1014 xfree(readset);
1015 if (writeset)
1016 xfree(writeset);
1017
1018 /* Terminate the session. */
1019
1020 /* Stop watching for window change. */
1021 if (have_pty)
1022 signal(SIGWINCH, SIG_DFL);
1023
1024 channel_free_all();
1025
1026 if (have_pty)
1027 leave_raw_mode();
1028
1029 /* restore blocking io */
1030 if (!isatty(fileno(stdin)))
1031 unset_nonblock(fileno(stdin));
1032 if (!isatty(fileno(stdout)))
1033 unset_nonblock(fileno(stdout));
1034 if (!isatty(fileno(stderr)))
1035 unset_nonblock(fileno(stderr));
1036
1037 if (received_signal) {
1038 if (in_non_blocking_mode) /* XXX */
1039 leave_non_blocking();
1040 fatal("Killed by signal %d.", (int) received_signal);
1041 }
1042
1043 /*
1044 * In interactive mode (with pseudo tty) display a message indicating
1045 * that the connection has been closed.
1046 */
1047 if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
1048 snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host);
1049 buffer_append(&stderr_buffer, buf, strlen(buf));
1050 }
1051
1052 /* Output any buffered data for stdout. */
1053 while (buffer_len(&stdout_buffer) > 0) {
1054 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
1055 buffer_len(&stdout_buffer));
1056 if (len <= 0) {
1057 error("Write failed flushing stdout buffer.");
1058 break;
1059 }
1060 buffer_consume(&stdout_buffer, len);
1061 stdout_bytes += len;
1062 }
1063
1064 /* Output any buffered data for stderr. */
1065 while (buffer_len(&stderr_buffer) > 0) {
1066 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
1067 buffer_len(&stderr_buffer));
1068 if (len <= 0) {
1069 error("Write failed flushing stderr buffer.");
1070 break;
1071 }
1072 buffer_consume(&stderr_buffer, len);
1073 stderr_bytes += len;
1074 }
1075
1076 /* Clear and free any buffers. */
1077 memset(buf, 0, sizeof(buf));
1078 buffer_free(&stdin_buffer);
1079 buffer_free(&stdout_buffer);
1080 buffer_free(&stderr_buffer);
1081
1082 /* Report bytes transferred, and transfer rates. */
1083 total_time = get_current_time() - start_time;
1084 debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
1085 stdin_bytes, stdout_bytes, stderr_bytes, total_time);
1086 if (total_time > 0)
1087 debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
1088 stdin_bytes / total_time, stdout_bytes / total_time,
1089 stderr_bytes / total_time);
1090
1091 /* Return the exit status of the program. */
1092 debug("Exit status %d", exit_status);
1093 return exit_status;
1094}
1095
1096/*********/
1097
1098static void
1099client_input_stdout_data(int type, u_int32_t seq, void *ctxt)
1100{
1101 u_int data_len;
1102 char *data = packet_get_string(&data_len);
1103 packet_check_eom();
1104 buffer_append(&stdout_buffer, data, data_len);
1105 memset(data, 0, data_len);
1106 xfree(data);
1107}
1108static void
1109client_input_stderr_data(int type, u_int32_t seq, void *ctxt)
1110{
1111 u_int data_len;
1112 char *data = packet_get_string(&data_len);
1113 packet_check_eom();
1114 buffer_append(&stderr_buffer, data, data_len);
1115 memset(data, 0, data_len);
1116 xfree(data);
1117}
1118static void
1119client_input_exit_status(int type, u_int32_t seq, void *ctxt)
1120{
1121 exit_status = packet_get_int();
1122 packet_check_eom();
1123 /* Acknowledge the exit. */
1124 packet_start(SSH_CMSG_EXIT_CONFIRMATION);
1125 packet_send();
1126 /*
1127 * Must wait for packet to be sent since we are
1128 * exiting the loop.
1129 */
1130 packet_write_wait();
1131 /* Flag that we want to exit. */
1132 quit_pending = 1;
1133}
1134
1135static Channel *
1136client_request_forwarded_tcpip(const char *request_type, int rchan)
1137{
1138 Channel *c = NULL;
1139 char *listen_address, *originator_address;
1140 int listen_port, originator_port;
1141 int sock;
1142
1143 /* Get rest of the packet */
1144 listen_address = packet_get_string(NULL);
1145 listen_port = packet_get_int();
1146 originator_address = packet_get_string(NULL);
1147 originator_port = packet_get_int();
1148 packet_check_eom();
1149
1150 debug("client_request_forwarded_tcpip: listen %s port %d, originator %s port %d",
1151 listen_address, listen_port, originator_address, originator_port);
1152
1153 sock = channel_connect_by_listen_address(listen_port);
1154 if (sock < 0) {
1155 xfree(originator_address);
1156 xfree(listen_address);
1157 return NULL;
1158 }
1159 c = channel_new("forwarded-tcpip",
1160 SSH_CHANNEL_CONNECTING, sock, sock, -1,
1161 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
1162 originator_address, 1);
1163 xfree(originator_address);
1164 xfree(listen_address);
1165 return c;
1166}
1167
1168static Channel *
1169client_request_x11(const char *request_type, int rchan)
1170{
1171 Channel *c = NULL;
1172 char *originator;
1173 int originator_port;
1174 int sock;
1175
1176 if (!options.forward_x11) {
1177 error("Warning: ssh server tried X11 forwarding.");
1178 error("Warning: this is probably a break in attempt by a malicious server.");
1179 return NULL;
1180 }
1181 originator = packet_get_string(NULL);
1182 if (datafellows & SSH_BUG_X11FWD) {
1183 debug2("buggy server: x11 request w/o originator_port");
1184 originator_port = 0;
1185 } else {
1186 originator_port = packet_get_int();
1187 }
1188 packet_check_eom();
1189 /* XXX check permission */
1190 debug("client_request_x11: request from %s %d", originator,
1191 originator_port);
1192 xfree(originator);
1193 sock = x11_connect_display();
1194 if (sock < 0)
1195 return NULL;
1196 c = channel_new("x11",
1197 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1198 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1199 c->force_drain = 1;
1200 return c;
1201}
1202
1203static Channel *
1204client_request_agent(const char *request_type, int rchan)
1205{
1206 Channel *c = NULL;
1207 int sock;
1208
1209 if (!options.forward_agent) {
1210 error("Warning: ssh server tried agent forwarding.");
1211 error("Warning: this is probably a break in attempt by a malicious server.");
1212 return NULL;
1213 }
1214 sock = ssh_get_authentication_socket();
1215 if (sock < 0)
1216 return NULL;
1217 c = channel_new("authentication agent connection",
1218 SSH_CHANNEL_OPEN, sock, sock, -1,
1219 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
1220 "authentication agent connection", 1);
1221 c->force_drain = 1;
1222 return c;
1223}
1224
1225/* XXXX move to generic input handler */
1226static void
1227client_input_channel_open(int type, u_int32_t seq, void *ctxt)
1228{
1229 Channel *c = NULL;
1230 char *ctype;
1231 int rchan;
1232 u_int rmaxpack, rwindow, len;
1233
1234 ctype = packet_get_string(&len);
1235 rchan = packet_get_int();
1236 rwindow = packet_get_int();
1237 rmaxpack = packet_get_int();
1238
1239 debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1240 ctype, rchan, rwindow, rmaxpack);
1241
1242 if (strcmp(ctype, "forwarded-tcpip") == 0) {
1243 c = client_request_forwarded_tcpip(ctype, rchan);
1244 } else if (strcmp(ctype, "x11") == 0) {
1245 c = client_request_x11(ctype, rchan);
1246 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1247 c = client_request_agent(ctype, rchan);
1248 }
1249/* XXX duplicate : */
1250 if (c != NULL) {
1251 debug("confirm %s", ctype);
1252 c->remote_id = rchan;
1253 c->remote_window = rwindow;
1254 c->remote_maxpacket = rmaxpack;
1255 if (c->type != SSH_CHANNEL_CONNECTING) {
1256 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1257 packet_put_int(c->remote_id);
1258 packet_put_int(c->self);
1259 packet_put_int(c->local_window);
1260 packet_put_int(c->local_maxpacket);
1261 packet_send();
1262 }
1263 } else {
1264 debug("failure %s", ctype);
1265 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1266 packet_put_int(rchan);
1267 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1268 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1269 packet_put_cstring("open failed");
1270 packet_put_cstring("");
1271 }
1272 packet_send();
1273 }
1274 xfree(ctype);
1275}
1276static void
1277client_input_channel_req(int type, u_int32_t seq, void *ctxt)
1278{
1279 Channel *c = NULL;
1280 int id, reply, success = 0;
1281 char *rtype;
1282
1283 id = packet_get_int();
1284 rtype = packet_get_string(NULL);
1285 reply = packet_get_char();
1286
1287 debug("client_input_channel_req: channel %d rtype %s reply %d",
1288 id, rtype, reply);
1289
1290 if (session_ident == -1) {
1291 error("client_input_channel_req: no channel %d", session_ident);
1292 } else if (id != session_ident) {
1293 error("client_input_channel_req: channel %d: wrong channel: %d",
1294 session_ident, id);
1295 }
1296 c = channel_lookup(id);
1297 if (c == NULL) {
1298 error("client_input_channel_req: channel %d: unknown channel", id);
1299 } else if (strcmp(rtype, "exit-status") == 0) {
1300 success = 1;
1301 exit_status = packet_get_int();
1302 packet_check_eom();
1303 }
1304 if (reply) {
1305 packet_start(success ?
1306 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1307 packet_put_int(c->remote_id);
1308 packet_send();
1309 }
1310 xfree(rtype);
1311}
1312static void
1313client_input_global_request(int type, u_int32_t seq, void *ctxt)
1314{
1315 char *rtype;
1316 int want_reply;
1317 int success = 0;
1318
1319 rtype = packet_get_string(NULL);
1320 want_reply = packet_get_char();
1321 debug("client_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1322 if (want_reply) {
1323 packet_start(success ?
1324 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1325 packet_send();
1326 packet_write_wait();
1327 }
1328 xfree(rtype);
1329}
1330
1331static void
1332client_init_dispatch_20(void)
1333{
1334 dispatch_init(&dispatch_protocol_error);
1335
1336 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1337 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1338 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1339 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1340 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
1341 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1342 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1343 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
1344 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1345 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
1346
1347 /* rekeying */
1348 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1349
1350 /* global request reply messages */
1351 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
1352 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
1353}
1354static void
1355client_init_dispatch_13(void)
1356{
1357 dispatch_init(NULL);
1358 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1359 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1360 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1361 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1362 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1363 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1364 dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
1365 dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
1366 dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);
1367
1368 dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
1369 &auth_input_open_request : &deny_input_open);
1370 dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
1371 &x11_input_open : &deny_input_open);
1372}
1373static void
1374client_init_dispatch_15(void)
1375{
1376 client_init_dispatch_13();
1377 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1378 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
1379}
1380static void
1381client_init_dispatch(void)
1382{
1383 if (compat20)
1384 client_init_dispatch_20();
1385 else if (compat13)
1386 client_init_dispatch_13();
1387 else
1388 client_init_dispatch_15();
1389}
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 * The main loop for the interactive session (client side).
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 *
13 *
14 * Copyright (c) 1999 Theo de Raadt. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 *
36 *
37 * SSH2 support added by Markus Friedl.
38 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved.
39 *
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
42 * are met:
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
50 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
51 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
52 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
53 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
54 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
55 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
56 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
57 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
58 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
59 */
60
61#include "includes.h"
62RCSID("$OpenBSD: clientloop.c,v 1.112 2003/06/28 16:23:06 deraadt Exp $");
63
64#include "ssh.h"
65#include "ssh1.h"
66#include "ssh2.h"
67#include "xmalloc.h"
68#include "packet.h"
69#include "buffer.h"
70#include "compat.h"
71#include "channels.h"
72#include "dispatch.h"
73#include "buffer.h"
74#include "bufaux.h"
75#include "key.h"
76#include "kex.h"
77#include "log.h"
78#include "readconf.h"
79#include "clientloop.h"
80#include "authfd.h"
81#include "atomicio.h"
82#include "sshtty.h"
83#include "misc.h"
84#include "readpass.h"
85
86/* import options */
87extern Options options;
88
89/* Flag indicating that stdin should be redirected from /dev/null. */
90extern int stdin_null_flag;
91
92/*
93 * Name of the host we are connecting to. This is the name given on the
94 * command line, or the HostName specified for the user-supplied name in a
95 * configuration file.
96 */
97extern char *host;
98
99/*
100 * Flag to indicate that we have received a window change signal which has
101 * not yet been processed. This will cause a message indicating the new
102 * window size to be sent to the server a little later. This is volatile
103 * because this is updated in a signal handler.
104 */
105static volatile sig_atomic_t received_window_change_signal = 0;
106static volatile sig_atomic_t received_signal = 0;
107
108/* Flag indicating whether the user\'s terminal is in non-blocking mode. */
109static int in_non_blocking_mode = 0;
110
111/* Common data for the client loop code. */
112static int quit_pending; /* Set to non-zero to quit the client loop. */
113static int escape_char; /* Escape character. */
114static int escape_pending; /* Last character was the escape character */
115static int last_was_cr; /* Last character was a newline. */
116static int exit_status; /* Used to store the exit status of the command. */
117static int stdin_eof; /* EOF has been encountered on standard error. */
118static Buffer stdin_buffer; /* Buffer for stdin data. */
119static Buffer stdout_buffer; /* Buffer for stdout data. */
120static Buffer stderr_buffer; /* Buffer for stderr data. */
121static u_long stdin_bytes, stdout_bytes, stderr_bytes;
122static u_int buffer_high;/* Soft max buffer size. */
123static int connection_in; /* Connection to server (input). */
124static int connection_out; /* Connection to server (output). */
125static int need_rekeying; /* Set to non-zero if rekeying is requested. */
126static int session_closed = 0; /* In SSH2: login session closed. */
127
128static void client_init_dispatch(void);
129int session_ident = -1;
130
131/*XXX*/
132extern Kex *xxx_kex;
133
134/* Restores stdin to blocking mode. */
135
136static void
137leave_non_blocking(void)
138{
139 if (in_non_blocking_mode) {
140 (void) fcntl(fileno(stdin), F_SETFL, 0);
141 in_non_blocking_mode = 0;
142 fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
143 }
144}
145
146/* Puts stdin terminal in non-blocking mode. */
147
148static void
149enter_non_blocking(void)
150{
151 in_non_blocking_mode = 1;
152 (void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
153 fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
154}
155
156/*
157 * Signal handler for the window change signal (SIGWINCH). This just sets a
158 * flag indicating that the window has changed.
159 */
160
161static void
162window_change_handler(int sig)
163{
164 received_window_change_signal = 1;
165 signal(SIGWINCH, window_change_handler);
166}
167
168/*
169 * Signal handler for signals that cause the program to terminate. These
170 * signals must be trapped to restore terminal modes.
171 */
172
173static void
174signal_handler(int sig)
175{
176 received_signal = sig;
177 quit_pending = 1;
178}
179
180/*
181 * Returns current time in seconds from Jan 1, 1970 with the maximum
182 * available resolution.
183 */
184
185static double
186get_current_time(void)
187{
188 struct timeval tv;
189 gettimeofday(&tv, NULL);
190 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
191}
192
193/*
194 * This is called when the interactive is entered. This checks if there is
195 * an EOF coming on stdin. We must check this explicitly, as select() does
196 * not appear to wake up when redirecting from /dev/null.
197 */
198
199static void
200client_check_initial_eof_on_stdin(void)
201{
202 int len;
203 char buf[1];
204
205 /*
206 * If standard input is to be "redirected from /dev/null", we simply
207 * mark that we have seen an EOF and send an EOF message to the
208 * server. Otherwise, we try to read a single character; it appears
209 * that for some files, such /dev/null, select() never wakes up for
210 * read for this descriptor, which means that we never get EOF. This
211 * way we will get the EOF if stdin comes from /dev/null or similar.
212 */
213 if (stdin_null_flag) {
214 /* Fake EOF on stdin. */
215 debug("Sending eof.");
216 stdin_eof = 1;
217 packet_start(SSH_CMSG_EOF);
218 packet_send();
219 } else {
220 enter_non_blocking();
221
222 /* Check for immediate EOF on stdin. */
223 len = read(fileno(stdin), buf, 1);
224 if (len == 0) {
225 /* EOF. Record that we have seen it and send EOF to server. */
226 debug("Sending eof.");
227 stdin_eof = 1;
228 packet_start(SSH_CMSG_EOF);
229 packet_send();
230 } else if (len > 0) {
231 /*
232 * Got data. We must store the data in the buffer,
233 * and also process it as an escape character if
234 * appropriate.
235 */
236 if ((u_char) buf[0] == escape_char)
237 escape_pending = 1;
238 else
239 buffer_append(&stdin_buffer, buf, 1);
240 }
241 leave_non_blocking();
242 }
243}
244
245
246/*
247 * Make packets from buffered stdin data, and buffer them for sending to the
248 * connection.
249 */
250
251static void
252client_make_packets_from_stdin_data(void)
253{
254 u_int len;
255
256 /* Send buffered stdin data to the server. */
257 while (buffer_len(&stdin_buffer) > 0 &&
258 packet_not_very_much_data_to_write()) {
259 len = buffer_len(&stdin_buffer);
260 /* Keep the packets at reasonable size. */
261 if (len > packet_get_maxsize())
262 len = packet_get_maxsize();
263 packet_start(SSH_CMSG_STDIN_DATA);
264 packet_put_string(buffer_ptr(&stdin_buffer), len);
265 packet_send();
266 buffer_consume(&stdin_buffer, len);
267 stdin_bytes += len;
268 /* If we have a pending EOF, send it now. */
269 if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
270 packet_start(SSH_CMSG_EOF);
271 packet_send();
272 }
273 }
274}
275
276/*
277 * Checks if the client window has changed, and sends a packet about it to
278 * the server if so. The actual change is detected elsewhere (by a software
279 * interrupt on Unix); this just checks the flag and sends a message if
280 * appropriate.
281 */
282
283static void
284client_check_window_change(void)
285{
286 struct winsize ws;
287
288 if (! received_window_change_signal)
289 return;
290 /** XXX race */
291 received_window_change_signal = 0;
292
293 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
294 return;
295
296 debug2("client_check_window_change: changed");
297
298 if (compat20) {
299 channel_request_start(session_ident, "window-change", 0);
300 packet_put_int(ws.ws_col);
301 packet_put_int(ws.ws_row);
302 packet_put_int(ws.ws_xpixel);
303 packet_put_int(ws.ws_ypixel);
304 packet_send();
305 } else {
306 packet_start(SSH_CMSG_WINDOW_SIZE);
307 packet_put_int(ws.ws_row);
308 packet_put_int(ws.ws_col);
309 packet_put_int(ws.ws_xpixel);
310 packet_put_int(ws.ws_ypixel);
311 packet_send();
312 }
313}
314
315/*
316 * Waits until the client can do something (some data becomes available on
317 * one of the file descriptors).
318 */
319
320static void
321client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
322 int *maxfdp, int *nallocp, int rekeying)
323{
324 /* Add any selections by the channel mechanism. */
325 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, rekeying);
326
327 if (!compat20) {
328 /* Read from the connection, unless our buffers are full. */
329 if (buffer_len(&stdout_buffer) < buffer_high &&
330 buffer_len(&stderr_buffer) < buffer_high &&
331 channel_not_very_much_buffered_data())
332 FD_SET(connection_in, *readsetp);
333 /*
334 * Read from stdin, unless we have seen EOF or have very much
335 * buffered data to send to the server.
336 */
337 if (!stdin_eof && packet_not_very_much_data_to_write())
338 FD_SET(fileno(stdin), *readsetp);
339
340 /* Select stdout/stderr if have data in buffer. */
341 if (buffer_len(&stdout_buffer) > 0)
342 FD_SET(fileno(stdout), *writesetp);
343 if (buffer_len(&stderr_buffer) > 0)
344 FD_SET(fileno(stderr), *writesetp);
345 } else {
346 /* channel_prepare_select could have closed the last channel */
347 if (session_closed && !channel_still_open() &&
348 !packet_have_data_to_write()) {
349 /* clear mask since we did not call select() */
350 memset(*readsetp, 0, *nallocp);
351 memset(*writesetp, 0, *nallocp);
352 return;
353 } else {
354 FD_SET(connection_in, *readsetp);
355 }
356 }
357
358 /* Select server connection if have data to write to the server. */
359 if (packet_have_data_to_write())
360 FD_SET(connection_out, *writesetp);
361
362 /*
363 * Wait for something to happen. This will suspend the process until
364 * some selected descriptor can be read, written, or has some other
365 * event pending. Note: if you want to implement SSH_MSG_IGNORE
366 * messages to fool traffic analysis, this might be the place to do
367 * it: just have a random timeout for the select, and send a random
368 * SSH_MSG_IGNORE packet when the timeout expires.
369 */
370
371 if (select((*maxfdp)+1, *readsetp, *writesetp, NULL, NULL) < 0) {
372 char buf[100];
373
374 /*
375 * We have to clear the select masks, because we return.
376 * We have to return, because the mainloop checks for the flags
377 * set by the signal handlers.
378 */
379 memset(*readsetp, 0, *nallocp);
380 memset(*writesetp, 0, *nallocp);
381
382 if (errno == EINTR)
383 return;
384 /* Note: we might still have data in the buffers. */
385 snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
386 buffer_append(&stderr_buffer, buf, strlen(buf));
387 quit_pending = 1;
388 }
389}
390
391static void
392client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
393{
394 struct winsize oldws, newws;
395
396 /* Flush stdout and stderr buffers. */
397 if (buffer_len(bout) > 0)
398 atomicio(vwrite, fileno(stdout), buffer_ptr(bout), buffer_len(bout));
399 if (buffer_len(berr) > 0)
400 atomicio(vwrite, fileno(stderr), buffer_ptr(berr), buffer_len(berr));
401
402 leave_raw_mode();
403
404 /*
405 * Free (and clear) the buffer to reduce the amount of data that gets
406 * written to swap.
407 */
408 buffer_free(bin);
409 buffer_free(bout);
410 buffer_free(berr);
411
412 /* Save old window size. */
413 ioctl(fileno(stdin), TIOCGWINSZ, &oldws);
414
415 /* Send the suspend signal to the program itself. */
416 kill(getpid(), SIGTSTP);
417
418 /* Check if the window size has changed. */
419 if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
420 (oldws.ws_row != newws.ws_row ||
421 oldws.ws_col != newws.ws_col ||
422 oldws.ws_xpixel != newws.ws_xpixel ||
423 oldws.ws_ypixel != newws.ws_ypixel))
424 received_window_change_signal = 1;
425
426 /* OK, we have been continued by the user. Reinitialize buffers. */
427 buffer_init(bin);
428 buffer_init(bout);
429 buffer_init(berr);
430
431 enter_raw_mode();
432}
433
434static void
435client_process_net_input(fd_set * readset)
436{
437 int len;
438 char buf[8192];
439
440 /*
441 * Read input from the server, and add any such data to the buffer of
442 * the packet subsystem.
443 */
444 if (FD_ISSET(connection_in, readset)) {
445 /* Read as much as possible. */
446 len = read(connection_in, buf, sizeof(buf));
447 if (len == 0) {
448 /* Received EOF. The remote host has closed the connection. */
449 snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n",
450 host);
451 buffer_append(&stderr_buffer, buf, strlen(buf));
452 quit_pending = 1;
453 return;
454 }
455 /*
456 * There is a kernel bug on Solaris that causes select to
457 * sometimes wake up even though there is no data available.
458 */
459 if (len < 0 && (errno == EAGAIN || errno == EINTR))
460 len = 0;
461
462 if (len < 0) {
463 /* An error has encountered. Perhaps there is a network problem. */
464 snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n",
465 host, strerror(errno));
466 buffer_append(&stderr_buffer, buf, strlen(buf));
467 quit_pending = 1;
468 return;
469 }
470 packet_process_incoming(buf, len);
471 }
472}
473
474static void
475process_cmdline(void)
476{
477 void (*handler)(int);
478 char *s, *cmd;
479 u_short fwd_port, fwd_host_port;
480 char buf[1024], sfwd_port[6], sfwd_host_port[6];
481 int local = 0;
482
483 leave_raw_mode();
484 handler = signal(SIGINT, SIG_IGN);
485 cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
486 if (s == NULL)
487 goto out;
488 while (*s && isspace(*s))
489 s++;
490 if (*s == 0)
491 goto out;
492 if (strlen(s) < 2 || s[0] != '-' || !(s[1] == 'L' || s[1] == 'R')) {
493 logit("Invalid command.");
494 goto out;
495 }
496 if (s[1] == 'L')
497 local = 1;
498 if (!local && !compat20) {
499 logit("Not supported for SSH protocol version 1.");
500 goto out;
501 }
502 s += 2;
503 while (*s && isspace(*s))
504 s++;
505
506 if (sscanf(s, "%5[0-9]:%255[^:]:%5[0-9]",
507 sfwd_port, buf, sfwd_host_port) != 3 &&
508 sscanf(s, "%5[0-9]/%255[^/]/%5[0-9]",
509 sfwd_port, buf, sfwd_host_port) != 3) {
510 logit("Bad forwarding specification.");
511 goto out;
512 }
513 if ((fwd_port = a2port(sfwd_port)) == 0 ||
514 (fwd_host_port = a2port(sfwd_host_port)) == 0) {
515 logit("Bad forwarding port(s).");
516 goto out;
517 }
518 if (local) {
519 if (channel_setup_local_fwd_listener(fwd_port, buf,
520 fwd_host_port, options.gateway_ports) < 0) {
521 logit("Port forwarding failed.");
522 goto out;
523 }
524 } else
525 channel_request_remote_forwarding(fwd_port, buf,
526 fwd_host_port);
527 logit("Forwarding port.");
528out:
529 signal(SIGINT, handler);
530 enter_raw_mode();
531 if (cmd)
532 xfree(cmd);
533}
534
535/* process the characters one by one */
536static int
537process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
538{
539 char string[1024];
540 pid_t pid;
541 int bytes = 0;
542 u_int i;
543 u_char ch;
544 char *s;
545
546 for (i = 0; i < len; i++) {
547 /* Get one character at a time. */
548 ch = buf[i];
549
550 if (escape_pending) {
551 /* We have previously seen an escape character. */
552 /* Clear the flag now. */
553 escape_pending = 0;
554
555 /* Process the escaped character. */
556 switch (ch) {
557 case '.':
558 /* Terminate the connection. */
559 snprintf(string, sizeof string, "%c.\r\n", escape_char);
560 buffer_append(berr, string, strlen(string));
561
562 quit_pending = 1;
563 return -1;
564
565 case 'Z' - 64:
566 /* Suspend the program. */
567 /* Print a message to that effect to the user. */
568 snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
569 buffer_append(berr, string, strlen(string));
570
571 /* Restore terminal modes and suspend. */
572 client_suspend_self(bin, bout, berr);
573
574 /* We have been continued. */
575 continue;
576
577 case 'B':
578 if (compat20) {
579 snprintf(string, sizeof string,
580 "%cB\r\n", escape_char);
581 buffer_append(berr, string,
582 strlen(string));
583 channel_request_start(session_ident,
584 "break", 0);
585 packet_put_int(1000);
586 packet_send();
587 }
588 continue;
589
590 case 'R':
591 if (compat20) {
592 if (datafellows & SSH_BUG_NOREKEY)
593 logit("Server does not support re-keying");
594 else
595 need_rekeying = 1;
596 }
597 continue;
598
599 case '&':
600 /*
601 * Detach the program (continue to serve connections,
602 * but put in background and no more new connections).
603 */
604 /* Restore tty modes. */
605 leave_raw_mode();
606
607 /* Stop listening for new connections. */
608 channel_stop_listening();
609
610 snprintf(string, sizeof string,
611 "%c& [backgrounded]\n", escape_char);
612 buffer_append(berr, string, strlen(string));
613
614 /* Fork into background. */
615 pid = fork();
616 if (pid < 0) {
617 error("fork: %.100s", strerror(errno));
618 continue;
619 }
620 if (pid != 0) { /* This is the parent. */
621 /* The parent just exits. */
622 exit(0);
623 }
624 /* The child continues serving connections. */
625 if (compat20) {
626 buffer_append(bin, "\004", 1);
627 /* fake EOF on stdin */
628 return -1;
629 } else if (!stdin_eof) {
630 /*
631 * Sending SSH_CMSG_EOF alone does not always appear
632 * to be enough. So we try to send an EOF character
633 * first.
634 */
635 packet_start(SSH_CMSG_STDIN_DATA);
636 packet_put_string("\004", 1);
637 packet_send();
638 /* Close stdin. */
639 stdin_eof = 1;
640 if (buffer_len(bin) == 0) {
641 packet_start(SSH_CMSG_EOF);
642 packet_send();
643 }
644 }
645 continue;
646
647 case '?':
648 snprintf(string, sizeof string,
649"%c?\r\n\
650Supported escape sequences:\r\n\
651%c. - terminate connection\r\n\
652%cB - send a BREAK to the remote system\r\n\
653%cC - open a command line\r\n\
654%cR - Request rekey (SSH protocol 2 only)\r\n\
655%c^Z - suspend ssh\r\n\
656%c# - list forwarded connections\r\n\
657%c& - background ssh (when waiting for connections to terminate)\r\n\
658%c? - this message\r\n\
659%c%c - send the escape character by typing it twice\r\n\
660(Note that escapes are only recognized immediately after newline.)\r\n",
661 escape_char, escape_char, escape_char, escape_char,
662 escape_char, escape_char, escape_char, escape_char,
663 escape_char, escape_char, escape_char);
664 buffer_append(berr, string, strlen(string));
665 continue;
666
667 case '#':
668 snprintf(string, sizeof string, "%c#\r\n", escape_char);
669 buffer_append(berr, string, strlen(string));
670 s = channel_open_message();
671 buffer_append(berr, s, strlen(s));
672 xfree(s);
673 continue;
674
675 case 'C':
676 process_cmdline();
677 continue;
678
679 default:
680 if (ch != escape_char) {
681 buffer_put_char(bin, escape_char);
682 bytes++;
683 }
684 /* Escaped characters fall through here */
685 break;
686 }
687 } else {
688 /*
689 * The previous character was not an escape char. Check if this
690 * is an escape.
691 */
692 if (last_was_cr && ch == escape_char) {
693 /* It is. Set the flag and continue to next character. */
694 escape_pending = 1;
695 continue;
696 }
697 }
698
699 /*
700 * Normal character. Record whether it was a newline,
701 * and append it to the buffer.
702 */
703 last_was_cr = (ch == '\r' || ch == '\n');
704 buffer_put_char(bin, ch);
705 bytes++;
706 }
707 return bytes;
708}
709
710static void
711client_process_input(fd_set * readset)
712{
713 int len;
714 char buf[8192];
715
716 /* Read input from stdin. */
717 if (FD_ISSET(fileno(stdin), readset)) {
718 /* Read as much as possible. */
719 len = read(fileno(stdin), buf, sizeof(buf));
720 if (len < 0 && (errno == EAGAIN || errno == EINTR))
721 return; /* we'll try again later */
722 if (len <= 0) {
723 /*
724 * Received EOF or error. They are treated
725 * similarly, except that an error message is printed
726 * if it was an error condition.
727 */
728 if (len < 0) {
729 snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno));
730 buffer_append(&stderr_buffer, buf, strlen(buf));
731 }
732 /* Mark that we have seen EOF. */
733 stdin_eof = 1;
734 /*
735 * Send an EOF message to the server unless there is
736 * data in the buffer. If there is data in the
737 * buffer, no message will be sent now. Code
738 * elsewhere will send the EOF when the buffer
739 * becomes empty if stdin_eof is set.
740 */
741 if (buffer_len(&stdin_buffer) == 0) {
742 packet_start(SSH_CMSG_EOF);
743 packet_send();
744 }
745 } else if (escape_char == SSH_ESCAPECHAR_NONE) {
746 /*
747 * Normal successful read, and no escape character.
748 * Just append the data to buffer.
749 */
750 buffer_append(&stdin_buffer, buf, len);
751 } else {
752 /*
753 * Normal, successful read. But we have an escape character
754 * and have to process the characters one by one.
755 */
756 if (process_escapes(&stdin_buffer, &stdout_buffer,
757 &stderr_buffer, buf, len) == -1)
758 return;
759 }
760 }
761}
762
763static void
764client_process_output(fd_set * writeset)
765{
766 int len;
767 char buf[100];
768
769 /* Write buffered output to stdout. */
770 if (FD_ISSET(fileno(stdout), writeset)) {
771 /* Write as much data as possible. */
772 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
773 buffer_len(&stdout_buffer));
774 if (len <= 0) {
775 if (errno == EINTR || errno == EAGAIN)
776 len = 0;
777 else {
778 /*
779 * An error or EOF was encountered. Put an
780 * error message to stderr buffer.
781 */
782 snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno));
783 buffer_append(&stderr_buffer, buf, strlen(buf));
784 quit_pending = 1;
785 return;
786 }
787 }
788 /* Consume printed data from the buffer. */
789 buffer_consume(&stdout_buffer, len);
790 stdout_bytes += len;
791 }
792 /* Write buffered output to stderr. */
793 if (FD_ISSET(fileno(stderr), writeset)) {
794 /* Write as much data as possible. */
795 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
796 buffer_len(&stderr_buffer));
797 if (len <= 0) {
798 if (errno == EINTR || errno == EAGAIN)
799 len = 0;
800 else {
801 /* EOF or error, but can't even print error message. */
802 quit_pending = 1;
803 return;
804 }
805 }
806 /* Consume printed characters from the buffer. */
807 buffer_consume(&stderr_buffer, len);
808 stderr_bytes += len;
809 }
810}
811
812/*
813 * Get packets from the connection input buffer, and process them as long as
814 * there are packets available.
815 *
816 * Any unknown packets received during the actual
817 * session cause the session to terminate. This is
818 * intended to make debugging easier since no
819 * confirmations are sent. Any compatible protocol
820 * extensions must be negotiated during the
821 * preparatory phase.
822 */
823
824static void
825client_process_buffered_input_packets(void)
826{
827 dispatch_run(DISPATCH_NONBLOCK, &quit_pending, compat20 ? xxx_kex : NULL);
828}
829
830/* scan buf[] for '~' before sending data to the peer */
831
832static int
833simple_escape_filter(Channel *c, char *buf, int len)
834{
835 /* XXX we assume c->extended is writeable */
836 return process_escapes(&c->input, &c->output, &c->extended, buf, len);
837}
838
839static void
840client_channel_closed(int id, void *arg)
841{
842 if (id != session_ident)
843 error("client_channel_closed: id %d != session_ident %d",
844 id, session_ident);
845 channel_cancel_cleanup(id);
846 session_closed = 1;
847 if (in_raw_mode())
848 leave_raw_mode();
849}
850
851/*
852 * Implements the interactive session with the server. This is called after
853 * the user has been authenticated, and a command has been started on the
854 * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character
855 * used as an escape character for terminating or suspending the session.
856 */
857
858int
859client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
860{
861 fd_set *readset = NULL, *writeset = NULL;
862 double start_time, total_time;
863 int max_fd = 0, max_fd2 = 0, len, rekeying = 0, nalloc = 0;
864 char buf[100];
865
866 debug("Entering interactive session.");
867
868 start_time = get_current_time();
869
870 /* Initialize variables. */
871 escape_pending = 0;
872 last_was_cr = 1;
873 exit_status = -1;
874 stdin_eof = 0;
875 buffer_high = 64 * 1024;
876 connection_in = packet_get_connection_in();
877 connection_out = packet_get_connection_out();
878 max_fd = MAX(connection_in, connection_out);
879
880 if (!compat20) {
881 /* enable nonblocking unless tty */
882 if (!isatty(fileno(stdin)))
883 set_nonblock(fileno(stdin));
884 if (!isatty(fileno(stdout)))
885 set_nonblock(fileno(stdout));
886 if (!isatty(fileno(stderr)))
887 set_nonblock(fileno(stderr));
888 max_fd = MAX(max_fd, fileno(stdin));
889 max_fd = MAX(max_fd, fileno(stdout));
890 max_fd = MAX(max_fd, fileno(stderr));
891 }
892 stdin_bytes = 0;
893 stdout_bytes = 0;
894 stderr_bytes = 0;
895 quit_pending = 0;
896 escape_char = escape_char_arg;
897
898 /* Initialize buffers. */
899 buffer_init(&stdin_buffer);
900 buffer_init(&stdout_buffer);
901 buffer_init(&stderr_buffer);
902
903 client_init_dispatch();
904
905 /*
906 * Set signal handlers, (e.g. to restore non-blocking mode)
907 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
908 */
909 if (signal(SIGINT, SIG_IGN) != SIG_IGN)
910 signal(SIGINT, signal_handler);
911 if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
912 signal(SIGQUIT, signal_handler);
913 if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
914 signal(SIGTERM, signal_handler);
915 if (have_pty)
916 signal(SIGWINCH, window_change_handler);
917
918 if (have_pty)
919 enter_raw_mode();
920
921 if (compat20) {
922 session_ident = ssh2_chan_id;
923 if (escape_char != SSH_ESCAPECHAR_NONE)
924 channel_register_filter(session_ident,
925 simple_escape_filter);
926 if (session_ident != -1)
927 channel_register_cleanup(session_ident,
928 client_channel_closed);
929 } else {
930 /* Check if we should immediately send eof on stdin. */
931 client_check_initial_eof_on_stdin();
932 }
933
934 /* Main loop of the client for the interactive session mode. */
935 while (!quit_pending) {
936
937 /* Process buffered packets sent by the server. */
938 client_process_buffered_input_packets();
939
940 if (compat20 && session_closed && !channel_still_open())
941 break;
942
943 rekeying = (xxx_kex != NULL && !xxx_kex->done);
944
945 if (rekeying) {
946 debug("rekeying in progress");
947 } else {
948 /*
949 * Make packets of buffered stdin data, and buffer
950 * them for sending to the server.
951 */
952 if (!compat20)
953 client_make_packets_from_stdin_data();
954
955 /*
956 * Make packets from buffered channel data, and
957 * enqueue them for sending to the server.
958 */
959 if (packet_not_very_much_data_to_write())
960 channel_output_poll();
961
962 /*
963 * Check if the window size has changed, and buffer a
964 * message about it to the server if so.
965 */
966 client_check_window_change();
967
968 if (quit_pending)
969 break;
970 }
971 /*
972 * Wait until we have something to do (something becomes
973 * available on one of the descriptors).
974 */
975 max_fd2 = max_fd;
976 client_wait_until_can_do_something(&readset, &writeset,
977 &max_fd2, &nalloc, rekeying);
978
979 if (quit_pending)
980 break;
981
982 /* Do channel operations unless rekeying in progress. */
983 if (!rekeying) {
984 channel_after_select(readset, writeset);
985 if (need_rekeying || packet_need_rekeying()) {
986 debug("need rekeying");
987 xxx_kex->done = 0;
988 kex_send_kexinit(xxx_kex);
989 need_rekeying = 0;
990 }
991 }
992
993 /* Buffer input from the connection. */
994 client_process_net_input(readset);
995
996 if (quit_pending)
997 break;
998
999 if (!compat20) {
1000 /* Buffer data from stdin */
1001 client_process_input(readset);
1002 /*
1003 * Process output to stdout and stderr. Output to
1004 * the connection is processed elsewhere (above).
1005 */
1006 client_process_output(writeset);
1007 }
1008
1009 /* Send as much buffered packet data as possible to the sender. */
1010 if (FD_ISSET(connection_out, writeset))
1011 packet_write_poll();
1012 }
1013 if (readset)
1014 xfree(readset);
1015 if (writeset)
1016 xfree(writeset);
1017
1018 /* Terminate the session. */
1019
1020 /* Stop watching for window change. */
1021 if (have_pty)
1022 signal(SIGWINCH, SIG_DFL);
1023
1024 channel_free_all();
1025
1026 if (have_pty)
1027 leave_raw_mode();
1028
1029 /* restore blocking io */
1030 if (!isatty(fileno(stdin)))
1031 unset_nonblock(fileno(stdin));
1032 if (!isatty(fileno(stdout)))
1033 unset_nonblock(fileno(stdout));
1034 if (!isatty(fileno(stderr)))
1035 unset_nonblock(fileno(stderr));
1036
1037 if (received_signal) {
1038 if (in_non_blocking_mode) /* XXX */
1039 leave_non_blocking();
1040 fatal("Killed by signal %d.", (int) received_signal);
1041 }
1042
1043 /*
1044 * In interactive mode (with pseudo tty) display a message indicating
1045 * that the connection has been closed.
1046 */
1047 if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
1048 snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host);
1049 buffer_append(&stderr_buffer, buf, strlen(buf));
1050 }
1051
1052 /* Output any buffered data for stdout. */
1053 while (buffer_len(&stdout_buffer) > 0) {
1054 len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
1055 buffer_len(&stdout_buffer));
1056 if (len <= 0) {
1057 error("Write failed flushing stdout buffer.");
1058 break;
1059 }
1060 buffer_consume(&stdout_buffer, len);
1061 stdout_bytes += len;
1062 }
1063
1064 /* Output any buffered data for stderr. */
1065 while (buffer_len(&stderr_buffer) > 0) {
1066 len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
1067 buffer_len(&stderr_buffer));
1068 if (len <= 0) {
1069 error("Write failed flushing stderr buffer.");
1070 break;
1071 }
1072 buffer_consume(&stderr_buffer, len);
1073 stderr_bytes += len;
1074 }
1075
1076 /* Clear and free any buffers. */
1077 memset(buf, 0, sizeof(buf));
1078 buffer_free(&stdin_buffer);
1079 buffer_free(&stdout_buffer);
1080 buffer_free(&stderr_buffer);
1081
1082 /* Report bytes transferred, and transfer rates. */
1083 total_time = get_current_time() - start_time;
1084 debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
1085 stdin_bytes, stdout_bytes, stderr_bytes, total_time);
1086 if (total_time > 0)
1087 debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
1088 stdin_bytes / total_time, stdout_bytes / total_time,
1089 stderr_bytes / total_time);
1090
1091 /* Return the exit status of the program. */
1092 debug("Exit status %d", exit_status);
1093 return exit_status;
1094}
1095
1096/*********/
1097
1098static void
1099client_input_stdout_data(int type, u_int32_t seq, void *ctxt)
1100{
1101 u_int data_len;
1102 char *data = packet_get_string(&data_len);
1103 packet_check_eom();
1104 buffer_append(&stdout_buffer, data, data_len);
1105 memset(data, 0, data_len);
1106 xfree(data);
1107}
1108static void
1109client_input_stderr_data(int type, u_int32_t seq, void *ctxt)
1110{
1111 u_int data_len;
1112 char *data = packet_get_string(&data_len);
1113 packet_check_eom();
1114 buffer_append(&stderr_buffer, data, data_len);
1115 memset(data, 0, data_len);
1116 xfree(data);
1117}
1118static void
1119client_input_exit_status(int type, u_int32_t seq, void *ctxt)
1120{
1121 exit_status = packet_get_int();
1122 packet_check_eom();
1123 /* Acknowledge the exit. */
1124 packet_start(SSH_CMSG_EXIT_CONFIRMATION);
1125 packet_send();
1126 /*
1127 * Must wait for packet to be sent since we are
1128 * exiting the loop.
1129 */
1130 packet_write_wait();
1131 /* Flag that we want to exit. */
1132 quit_pending = 1;
1133}
1134
1135static Channel *
1136client_request_forwarded_tcpip(const char *request_type, int rchan)
1137{
1138 Channel *c = NULL;
1139 char *listen_address, *originator_address;
1140 int listen_port, originator_port;
1141 int sock;
1142
1143 /* Get rest of the packet */
1144 listen_address = packet_get_string(NULL);
1145 listen_port = packet_get_int();
1146 originator_address = packet_get_string(NULL);
1147 originator_port = packet_get_int();
1148 packet_check_eom();
1149
1150 debug("client_request_forwarded_tcpip: listen %s port %d, originator %s port %d",
1151 listen_address, listen_port, originator_address, originator_port);
1152
1153 sock = channel_connect_by_listen_address(listen_port);
1154 if (sock < 0) {
1155 xfree(originator_address);
1156 xfree(listen_address);
1157 return NULL;
1158 }
1159 c = channel_new("forwarded-tcpip",
1160 SSH_CHANNEL_CONNECTING, sock, sock, -1,
1161 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
1162 originator_address, 1);
1163 xfree(originator_address);
1164 xfree(listen_address);
1165 return c;
1166}
1167
1168static Channel *
1169client_request_x11(const char *request_type, int rchan)
1170{
1171 Channel *c = NULL;
1172 char *originator;
1173 int originator_port;
1174 int sock;
1175
1176 if (!options.forward_x11) {
1177 error("Warning: ssh server tried X11 forwarding.");
1178 error("Warning: this is probably a break in attempt by a malicious server.");
1179 return NULL;
1180 }
1181 originator = packet_get_string(NULL);
1182 if (datafellows & SSH_BUG_X11FWD) {
1183 debug2("buggy server: x11 request w/o originator_port");
1184 originator_port = 0;
1185 } else {
1186 originator_port = packet_get_int();
1187 }
1188 packet_check_eom();
1189 /* XXX check permission */
1190 debug("client_request_x11: request from %s %d", originator,
1191 originator_port);
1192 xfree(originator);
1193 sock = x11_connect_display();
1194 if (sock < 0)
1195 return NULL;
1196 c = channel_new("x11",
1197 SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1198 CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1199 c->force_drain = 1;
1200 return c;
1201}
1202
1203static Channel *
1204client_request_agent(const char *request_type, int rchan)
1205{
1206 Channel *c = NULL;
1207 int sock;
1208
1209 if (!options.forward_agent) {
1210 error("Warning: ssh server tried agent forwarding.");
1211 error("Warning: this is probably a break in attempt by a malicious server.");
1212 return NULL;
1213 }
1214 sock = ssh_get_authentication_socket();
1215 if (sock < 0)
1216 return NULL;
1217 c = channel_new("authentication agent connection",
1218 SSH_CHANNEL_OPEN, sock, sock, -1,
1219 CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_WINDOW_DEFAULT, 0,
1220 "authentication agent connection", 1);
1221 c->force_drain = 1;
1222 return c;
1223}
1224
1225/* XXXX move to generic input handler */
1226static void
1227client_input_channel_open(int type, u_int32_t seq, void *ctxt)
1228{
1229 Channel *c = NULL;
1230 char *ctype;
1231 int rchan;
1232 u_int rmaxpack, rwindow, len;
1233
1234 ctype = packet_get_string(&len);
1235 rchan = packet_get_int();
1236 rwindow = packet_get_int();
1237 rmaxpack = packet_get_int();
1238
1239 debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
1240 ctype, rchan, rwindow, rmaxpack);
1241
1242 if (strcmp(ctype, "forwarded-tcpip") == 0) {
1243 c = client_request_forwarded_tcpip(ctype, rchan);
1244 } else if (strcmp(ctype, "x11") == 0) {
1245 c = client_request_x11(ctype, rchan);
1246 } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
1247 c = client_request_agent(ctype, rchan);
1248 }
1249/* XXX duplicate : */
1250 if (c != NULL) {
1251 debug("confirm %s", ctype);
1252 c->remote_id = rchan;
1253 c->remote_window = rwindow;
1254 c->remote_maxpacket = rmaxpack;
1255 if (c->type != SSH_CHANNEL_CONNECTING) {
1256 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1257 packet_put_int(c->remote_id);
1258 packet_put_int(c->self);
1259 packet_put_int(c->local_window);
1260 packet_put_int(c->local_maxpacket);
1261 packet_send();
1262 }
1263 } else {
1264 debug("failure %s", ctype);
1265 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1266 packet_put_int(rchan);
1267 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1268 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1269 packet_put_cstring("open failed");
1270 packet_put_cstring("");
1271 }
1272 packet_send();
1273 }
1274 xfree(ctype);
1275}
1276static void
1277client_input_channel_req(int type, u_int32_t seq, void *ctxt)
1278{
1279 Channel *c = NULL;
1280 int id, reply, success = 0;
1281 char *rtype;
1282
1283 id = packet_get_int();
1284 rtype = packet_get_string(NULL);
1285 reply = packet_get_char();
1286
1287 debug("client_input_channel_req: channel %d rtype %s reply %d",
1288 id, rtype, reply);
1289
1290 if (session_ident == -1) {
1291 error("client_input_channel_req: no channel %d", session_ident);
1292 } else if (id != session_ident) {
1293 error("client_input_channel_req: channel %d: wrong channel: %d",
1294 session_ident, id);
1295 }
1296 c = channel_lookup(id);
1297 if (c == NULL) {
1298 error("client_input_channel_req: channel %d: unknown channel", id);
1299 } else if (strcmp(rtype, "exit-status") == 0) {
1300 success = 1;
1301 exit_status = packet_get_int();
1302 packet_check_eom();
1303 }
1304 if (reply) {
1305 packet_start(success ?
1306 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1307 packet_put_int(c->remote_id);
1308 packet_send();
1309 }
1310 xfree(rtype);
1311}
1312static void
1313client_input_global_request(int type, u_int32_t seq, void *ctxt)
1314{
1315 char *rtype;
1316 int want_reply;
1317 int success = 0;
1318
1319 rtype = packet_get_string(NULL);
1320 want_reply = packet_get_char();
1321 debug("client_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1322 if (want_reply) {
1323 packet_start(success ?
1324 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1325 packet_send();
1326 packet_write_wait();
1327 }
1328 xfree(rtype);
1329}
1330
1331static void
1332client_init_dispatch_20(void)
1333{
1334 dispatch_init(&dispatch_protocol_error);
1335
1336 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1337 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1338 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1339 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1340 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
1341 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1342 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1343 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
1344 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1345 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
1346
1347 /* rekeying */
1348 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1349
1350 /* global request reply messages */
1351 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
1352 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
1353}
1354static void
1355client_init_dispatch_13(void)
1356{
1357 dispatch_init(NULL);
1358 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1359 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1360 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1361 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1362 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1363 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1364 dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
1365 dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
1366 dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);
1367
1368 dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
1369 &auth_input_open_request : &deny_input_open);
1370 dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
1371 &x11_input_open : &deny_input_open);
1372}
1373static void
1374client_init_dispatch_15(void)
1375{
1376 client_init_dispatch_13();
1377 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1378 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
1379}
1380static void
1381client_init_dispatch(void)
1382{
1383 if (compat20)
1384 client_init_dispatch_20();
1385 else if (compat13)
1386 client_init_dispatch_13();
1387 else
1388 client_init_dispatch_15();
1389}