Annotation of src/usr.bin/ssh/clientloop.c, Revision 1.13
1.1 deraadt 1: /*
1.12 deraadt 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: */
1.1 deraadt 16:
17: #include "includes.h"
1.13 ! markus 18: RCSID("$Id: clientloop.c,v 1.12 1999/11/24 00:26:01 deraadt Exp $");
1.1 deraadt 19:
20: #include "xmalloc.h"
21: #include "ssh.h"
22: #include "packet.h"
23: #include "buffer.h"
24: #include "authfd.h"
1.8 markus 25: #include "readconf.h"
1.1 deraadt 26:
27: /* Flag indicating that stdin should be redirected from /dev/null. */
28: extern int stdin_null_flag;
29:
1.13 ! markus 30: /*
! 31: * Name of the host we are connecting to. This is the name given on the
! 32: * command line, or the HostName specified for the user-supplied name in a
! 33: * configuration file.
! 34: */
1.1 deraadt 35: extern char *host;
36:
1.13 ! markus 37: /*
! 38: * Flag to indicate that we have received a window change signal which has
! 39: * not yet been processed. This will cause a message indicating the new
! 40: * window size to be sent to the server a little later. This is volatile
! 41: * because this is updated in a signal handler.
! 42: */
1.1 deraadt 43: static volatile int received_window_change_signal = 0;
44:
45: /* Terminal modes, as saved by enter_raw_mode. */
46: static struct termios saved_tio;
47:
1.13 ! markus 48: /*
! 49: * Flag indicating whether we are in raw mode. This is used by
! 50: * enter_raw_mode and leave_raw_mode.
! 51: */
1.1 deraadt 52: static int in_raw_mode = 0;
53:
54: /* Flag indicating whether the user\'s terminal is in non-blocking mode. */
55: static int in_non_blocking_mode = 0;
56:
57: /* Common data for the client loop code. */
1.11 markus 58: static int escape_pending; /* Last character was the escape character */
59: static int last_was_cr; /* Last character was a newline. */
60: static int exit_status; /* Used to store the exit status of the command. */
61: static int stdin_eof; /* EOF has been encountered on standard error. */
62: static Buffer stdin_buffer; /* Buffer for stdin data. */
63: static Buffer stdout_buffer; /* Buffer for stdout data. */
64: static Buffer stderr_buffer; /* Buffer for stderr data. */
65: static unsigned int buffer_high;/* Soft max buffer size. */
66: static int max_fd; /* Maximum file descriptor number in select(). */
67: static int connection_in; /* Connection to server (input). */
68: static int connection_out; /* Connection to server (output). */
1.1 deraadt 69: static unsigned long stdin_bytes, stdout_bytes, stderr_bytes;
1.11 markus 70: static int quit_pending; /* Set to non-zero to quit the client loop. */
71: static int escape_char; /* Escape character. */
1.1 deraadt 72:
1.13 ! markus 73: /* Returns the user\'s terminal to normal mode if it had been put in raw mode. */
1.1 deraadt 74:
1.11 markus 75: void
76: leave_raw_mode()
1.1 deraadt 77: {
1.11 markus 78: if (!in_raw_mode)
79: return;
80: in_raw_mode = 0;
81: if (tcsetattr(fileno(stdin), TCSADRAIN, &saved_tio) < 0)
82: perror("tcsetattr");
1.1 deraadt 83:
1.11 markus 84: fatal_remove_cleanup((void (*) (void *)) leave_raw_mode, NULL);
1.1 deraadt 85: }
86:
87: /* Puts the user\'s terminal in raw mode. */
88:
1.11 markus 89: void
90: enter_raw_mode()
1.1 deraadt 91: {
1.11 markus 92: struct termios tio;
1.1 deraadt 93:
1.11 markus 94: if (tcgetattr(fileno(stdin), &tio) < 0)
95: perror("tcgetattr");
96: saved_tio = tio;
97: tio.c_iflag |= IGNPAR;
98: tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
99: tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
1.1 deraadt 100: #ifdef IEXTEN
1.11 markus 101: tio.c_lflag &= ~IEXTEN;
102: #endif /* IEXTEN */
103: tio.c_oflag &= ~OPOST;
104: tio.c_cc[VMIN] = 1;
105: tio.c_cc[VTIME] = 0;
106: if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) < 0)
107: perror("tcsetattr");
108: in_raw_mode = 1;
1.1 deraadt 109:
1.11 markus 110: fatal_add_cleanup((void (*) (void *)) leave_raw_mode, NULL);
111: }
1.1 deraadt 112:
113: /* Restores stdin to blocking mode. */
114:
1.11 markus 115: void
116: leave_non_blocking()
1.1 deraadt 117: {
1.11 markus 118: if (in_non_blocking_mode) {
119: (void) fcntl(fileno(stdin), F_SETFL, 0);
120: in_non_blocking_mode = 0;
121: fatal_remove_cleanup((void (*) (void *)) leave_non_blocking, NULL);
122: }
1.1 deraadt 123: }
124:
1.11 markus 125: /* Puts stdin terminal in non-blocking mode. */
126:
127: void
128: enter_non_blocking()
1.1 deraadt 129: {
1.11 markus 130: in_non_blocking_mode = 1;
131: (void) fcntl(fileno(stdin), F_SETFL, O_NONBLOCK);
132: fatal_add_cleanup((void (*) (void *)) leave_non_blocking, NULL);
1.1 deraadt 133: }
134:
1.13 ! markus 135: /*
! 136: * Signal handler for the window change signal (SIGWINCH). This just sets a
! 137: * flag indicating that the window has changed.
! 138: */
1.1 deraadt 139:
1.11 markus 140: void
141: window_change_handler(int sig)
1.1 deraadt 142: {
1.11 markus 143: received_window_change_signal = 1;
144: signal(SIGWINCH, window_change_handler);
1.1 deraadt 145: }
146:
1.13 ! markus 147: /*
! 148: * Signal handler for signals that cause the program to terminate. These
! 149: * signals must be trapped to restore terminal modes.
! 150: */
1.1 deraadt 151:
1.11 markus 152: void
153: signal_handler(int sig)
1.1 deraadt 154: {
1.11 markus 155: if (in_raw_mode)
156: leave_raw_mode();
157: if (in_non_blocking_mode)
158: leave_non_blocking();
159: channel_stop_listening();
160: packet_close();
161: fatal("Killed by signal %d.", sig);
1.1 deraadt 162: }
163:
1.13 ! markus 164: /*
! 165: * Returns current time in seconds from Jan 1, 1970 with the maximum
! 166: * available resolution.
! 167: */
1.1 deraadt 168:
1.11 markus 169: double
170: get_current_time()
1.1 deraadt 171: {
1.11 markus 172: struct timeval tv;
173: gettimeofday(&tv, NULL);
174: return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
1.1 deraadt 175: }
176:
1.13 ! markus 177: /*
! 178: * This is called when the interactive is entered. This checks if there is
! 179: * an EOF coming on stdin. We must check this explicitly, as select() does
! 180: * not appear to wake up when redirecting from /dev/null.
! 181: */
1.1 deraadt 182:
1.11 markus 183: void
184: client_check_initial_eof_on_stdin()
1.1 deraadt 185: {
1.11 markus 186: int len;
187: char buf[1];
1.1 deraadt 188:
1.13 ! markus 189: /*
! 190: * If standard input is to be "redirected from /dev/null", we simply
! 191: * mark that we have seen an EOF and send an EOF message to the
! 192: * server. Otherwise, we try to read a single character; it appears
! 193: * that for some files, such /dev/null, select() never wakes up for
! 194: * read for this descriptor, which means that we never get EOF. This
! 195: * way we will get the EOF if stdin comes from /dev/null or similar.
! 196: */
1.11 markus 197: if (stdin_null_flag) {
198: /* Fake EOF on stdin. */
199: debug("Sending eof.");
200: stdin_eof = 1;
201: packet_start(SSH_CMSG_EOF);
202: packet_send();
203: } else {
204: enter_non_blocking();
205:
206: /* Check for immediate EOF on stdin. */
207: len = read(fileno(stdin), buf, 1);
208: if (len == 0) {
1.13 ! markus 209: /* EOF. Record that we have seen it and send EOF to server. */
1.11 markus 210: debug("Sending eof.");
211: stdin_eof = 1;
212: packet_start(SSH_CMSG_EOF);
213: packet_send();
214: } else if (len > 0) {
1.13 ! markus 215: /*
! 216: * Got data. We must store the data in the buffer,
! 217: * and also process it as an escape character if
! 218: * appropriate.
! 219: */
1.11 markus 220: if ((unsigned char) buf[0] == escape_char)
221: escape_pending = 1;
222: else {
223: buffer_append(&stdin_buffer, buf, 1);
224: stdin_bytes += 1;
225: }
226: }
227: leave_non_blocking();
228: }
1.1 deraadt 229: }
230:
1.13 ! markus 231: /*
! 232: * Get packets from the connection input buffer, and process them as long as
! 233: * there are packets available.
! 234: */
1.1 deraadt 235:
1.11 markus 236: void
237: client_process_buffered_input_packets()
1.1 deraadt 238: {
1.11 markus 239: int type;
240: char *data;
241: unsigned int data_len;
242: int payload_len;
243:
244: /* Process any buffered packets from the server. */
245: while (!quit_pending &&
246: (type = packet_read_poll(&payload_len)) != SSH_MSG_NONE) {
247: switch (type) {
248:
249: case SSH_SMSG_STDOUT_DATA:
250: data = packet_get_string(&data_len);
251: packet_integrity_check(payload_len, 4 + data_len, type);
252: buffer_append(&stdout_buffer, data, data_len);
253: stdout_bytes += data_len;
254: memset(data, 0, data_len);
255: xfree(data);
256: break;
257:
258: case SSH_SMSG_STDERR_DATA:
259: data = packet_get_string(&data_len);
260: packet_integrity_check(payload_len, 4 + data_len, type);
261: buffer_append(&stderr_buffer, data, data_len);
262: stdout_bytes += data_len;
263: memset(data, 0, data_len);
264: xfree(data);
265: break;
266:
267: case SSH_SMSG_EXITSTATUS:
268: packet_integrity_check(payload_len, 4, type);
269: exit_status = packet_get_int();
270: /* Acknowledge the exit. */
271: packet_start(SSH_CMSG_EXIT_CONFIRMATION);
272: packet_send();
1.13 ! markus 273: /*
! 274: * Must wait for packet to be sent since we are
! 275: * exiting the loop.
! 276: */
1.11 markus 277: packet_write_wait();
278: /* Flag that we want to exit. */
279: quit_pending = 1;
280: break;
281:
282: case SSH_SMSG_X11_OPEN:
283: x11_input_open(payload_len);
284: break;
285:
286: case SSH_MSG_PORT_OPEN:
287: channel_input_port_open(payload_len);
288: break;
289:
290: case SSH_SMSG_AGENT_OPEN:
291: packet_integrity_check(payload_len, 4, type);
292: auth_input_open_request();
293: break;
294:
295: case SSH_MSG_CHANNEL_OPEN_CONFIRMATION:
296: packet_integrity_check(payload_len, 4 + 4, type);
297: channel_input_open_confirmation();
298: break;
299:
300: case SSH_MSG_CHANNEL_OPEN_FAILURE:
301: packet_integrity_check(payload_len, 4, type);
302: channel_input_open_failure();
303: break;
304:
305: case SSH_MSG_CHANNEL_DATA:
306: channel_input_data(payload_len);
307: break;
308:
309: case SSH_MSG_CHANNEL_CLOSE:
310: packet_integrity_check(payload_len, 4, type);
311: channel_input_close();
312: break;
313:
314: case SSH_MSG_CHANNEL_CLOSE_CONFIRMATION:
315: packet_integrity_check(payload_len, 4, type);
316: channel_input_close_confirmation();
317: break;
318:
319: default:
1.13 ! markus 320: /*
! 321: * Any unknown packets received during the actual
! 322: * session cause the session to terminate. This is
! 323: * intended to make debugging easier since no
! 324: * confirmations are sent. Any compatible protocol
! 325: * extensions must be negotiated during the
! 326: * preparatory phase.
! 327: */
1.11 markus 328: packet_disconnect("Protocol error during session: type %d",
329: type);
330: }
1.1 deraadt 331: }
332: }
333:
1.13 ! markus 334: /*
! 335: * Make packets from buffered stdin data, and buffer them for sending to the
! 336: * connection.
! 337: */
1.1 deraadt 338:
1.11 markus 339: void
340: client_make_packets_from_stdin_data()
1.1 deraadt 341: {
1.11 markus 342: unsigned int len;
1.1 deraadt 343:
1.11 markus 344: /* Send buffered stdin data to the server. */
345: while (buffer_len(&stdin_buffer) > 0 &&
346: packet_not_very_much_data_to_write()) {
347: len = buffer_len(&stdin_buffer);
348: /* Keep the packets at reasonable size. */
349: if (len > packet_get_maxsize())
350: len = packet_get_maxsize();
351: packet_start(SSH_CMSG_STDIN_DATA);
352: packet_put_string(buffer_ptr(&stdin_buffer), len);
353: packet_send();
354: buffer_consume(&stdin_buffer, len);
355: /* If we have a pending EOF, send it now. */
356: if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
357: packet_start(SSH_CMSG_EOF);
358: packet_send();
359: }
1.1 deraadt 360: }
361: }
362:
1.13 ! markus 363: /*
! 364: * Checks if the client window has changed, and sends a packet about it to
! 365: * the server if so. The actual change is detected elsewhere (by a software
! 366: * interrupt on Unix); this just checks the flag and sends a message if
! 367: * appropriate.
! 368: */
1.1 deraadt 369:
1.11 markus 370: void
371: client_check_window_change()
1.1 deraadt 372: {
1.11 markus 373: /* Send possible window change message to the server. */
374: if (received_window_change_signal) {
375: struct winsize ws;
376:
377: /* Clear the window change indicator. */
378: received_window_change_signal = 0;
379:
380: /* Read new window size. */
381: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) >= 0) {
382: /* Successful, send the packet now. */
383: packet_start(SSH_CMSG_WINDOW_SIZE);
384: packet_put_int(ws.ws_row);
385: packet_put_int(ws.ws_col);
386: packet_put_int(ws.ws_xpixel);
387: packet_put_int(ws.ws_ypixel);
388: packet_send();
389: }
1.1 deraadt 390: }
391: }
392:
1.13 ! markus 393: /*
! 394: * Waits until the client can do something (some data becomes available on
! 395: * one of the file descriptors).
! 396: */
1.1 deraadt 397:
1.11 markus 398: void
399: client_wait_until_can_do_something(fd_set * readset, fd_set * writeset)
400: {
401: /* Initialize select masks. */
402: FD_ZERO(readset);
403:
404: /* Read from the connection, unless our buffers are full. */
405: if (buffer_len(&stdout_buffer) < buffer_high &&
406: buffer_len(&stderr_buffer) < buffer_high &&
407: channel_not_very_much_buffered_data())
408: FD_SET(connection_in, readset);
409:
1.13 ! markus 410: /*
! 411: * Read from stdin, unless we have seen EOF or have very much
! 412: * buffered data to send to the server.
! 413: */
1.11 markus 414: if (!stdin_eof && packet_not_very_much_data_to_write())
415: FD_SET(fileno(stdin), readset);
416:
417: FD_ZERO(writeset);
418:
419: /* Add any selections by the channel mechanism. */
420: channel_prepare_select(readset, writeset);
421:
422: /* Select server connection if have data to write to the server. */
423: if (packet_have_data_to_write())
424: FD_SET(connection_out, writeset);
425:
426: /* Select stdout if have data in buffer. */
427: if (buffer_len(&stdout_buffer) > 0)
428: FD_SET(fileno(stdout), writeset);
429:
430: /* Select stderr if have data in buffer. */
431: if (buffer_len(&stderr_buffer) > 0)
432: FD_SET(fileno(stderr), writeset);
433:
434: /* Update maximum file descriptor number, if appropriate. */
435: if (channel_max_fd() > max_fd)
436: max_fd = channel_max_fd();
437:
1.13 ! markus 438: /*
! 439: * Wait for something to happen. This will suspend the process until
! 440: * some selected descriptor can be read, written, or has some other
! 441: * event pending. Note: if you want to implement SSH_MSG_IGNORE
! 442: * messages to fool traffic analysis, this might be the place to do
! 443: * it: just have a random timeout for the select, and send a random
! 444: * SSH_MSG_IGNORE packet when the timeout expires.
! 445: */
1.11 markus 446:
447: if (select(max_fd + 1, readset, writeset, NULL, NULL) < 0) {
448: char buf[100];
449: /* Some systems fail to clear these automatically. */
450: FD_ZERO(readset);
451: FD_ZERO(writeset);
452: if (errno == EINTR)
453: return;
454: /* Note: we might still have data in the buffers. */
455: snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
456: buffer_append(&stderr_buffer, buf, strlen(buf));
457: stderr_bytes += strlen(buf);
458: quit_pending = 1;
459: }
460: }
461:
462: void
463: client_suspend_self()
1.1 deraadt 464: {
1.11 markus 465: struct winsize oldws, newws;
466:
467: /* Flush stdout and stderr buffers. */
468: if (buffer_len(&stdout_buffer) > 0)
469: write(fileno(stdout),
470: buffer_ptr(&stdout_buffer),
471: buffer_len(&stdout_buffer));
472: if (buffer_len(&stderr_buffer) > 0)
473: write(fileno(stderr),
474: buffer_ptr(&stderr_buffer),
475: buffer_len(&stderr_buffer));
476:
477: leave_raw_mode();
478:
1.13 ! markus 479: /*
! 480: * Free (and clear) the buffer to reduce the amount of data that gets
! 481: * written to swap.
! 482: */
1.11 markus 483: buffer_free(&stdin_buffer);
484: buffer_free(&stdout_buffer);
485: buffer_free(&stderr_buffer);
486:
487: /* Save old window size. */
488: ioctl(fileno(stdin), TIOCGWINSZ, &oldws);
489:
490: /* Send the suspend signal to the program itself. */
491: kill(getpid(), SIGTSTP);
492:
493: /* Check if the window size has changed. */
494: if (ioctl(fileno(stdin), TIOCGWINSZ, &newws) >= 0 &&
495: (oldws.ws_row != newws.ws_row ||
496: oldws.ws_col != newws.ws_col ||
497: oldws.ws_xpixel != newws.ws_xpixel ||
498: oldws.ws_ypixel != newws.ws_ypixel))
499: received_window_change_signal = 1;
500:
501: /* OK, we have been continued by the user. Reinitialize buffers. */
502: buffer_init(&stdin_buffer);
503: buffer_init(&stdout_buffer);
504: buffer_init(&stderr_buffer);
505:
506: enter_raw_mode();
507: }
508:
509: void
510: client_process_input(fd_set * readset)
511: {
512: int len, pid;
513: char buf[8192], *s;
514:
1.13 ! markus 515: /*
! 516: * Read input from the server, and add any such data to the buffer of
! 517: * the packet subsystem.
! 518: */
1.11 markus 519: if (FD_ISSET(connection_in, readset)) {
520: /* Read as much as possible. */
521: len = read(connection_in, buf, sizeof(buf));
522: if (len == 0) {
523: /* Received EOF. The remote host has closed the connection. */
524: snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n",
525: host);
1.1 deraadt 526: buffer_append(&stderr_buffer, buf, strlen(buf));
527: stderr_bytes += strlen(buf);
528: quit_pending = 1;
529: return;
1.11 markus 530: }
1.13 ! markus 531: /*
! 532: * There is a kernel bug on Solaris that causes select to
! 533: * sometimes wake up even though there is no data available.
! 534: */
1.11 markus 535: if (len < 0 && errno == EAGAIN)
536: len = 0;
537:
538: if (len < 0) {
539: /* An error has encountered. Perhaps there is a network problem. */
540: snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n",
541: host, strerror(errno));
542: buffer_append(&stderr_buffer, buf, strlen(buf));
543: stderr_bytes += strlen(buf);
544: quit_pending = 1;
545: return;
546: }
547: packet_process_incoming(buf, len);
548: }
549: /* Read input from stdin. */
550: if (FD_ISSET(fileno(stdin), readset)) {
551: /* Read as much as possible. */
552: len = read(fileno(stdin), buf, sizeof(buf));
553: if (len <= 0) {
1.13 ! markus 554: /*
! 555: * Received EOF or error. They are treated
! 556: * similarly, except that an error message is printed
! 557: * if it was an error condition.
! 558: */
1.11 markus 559: if (len < 0) {
560: snprintf(buf, sizeof buf, "read: %.100s\r\n", strerror(errno));
561: buffer_append(&stderr_buffer, buf, strlen(buf));
562: stderr_bytes += strlen(buf);
563: }
564: /* Mark that we have seen EOF. */
565: stdin_eof = 1;
1.13 ! markus 566: /*
! 567: * Send an EOF message to the server unless there is
! 568: * data in the buffer. If there is data in the
! 569: * buffer, no message will be sent now. Code
! 570: * elsewhere will send the EOF when the buffer
! 571: * becomes empty if stdin_eof is set.
! 572: */
1.11 markus 573: if (buffer_len(&stdin_buffer) == 0) {
1.1 deraadt 574: packet_start(SSH_CMSG_EOF);
575: packet_send();
1.11 markus 576: }
577: } else if (escape_char == -1) {
1.13 ! markus 578: /*
! 579: * Normal successful read, and no escape character.
! 580: * Just append the data to buffer.
! 581: */
1.11 markus 582: buffer_append(&stdin_buffer, buf, len);
583: stdin_bytes += len;
584: } else {
1.13 ! markus 585: /*
! 586: * Normal, successful read. But we have an escape character
! 587: * and have to process the characters one by one.
! 588: */
1.11 markus 589: unsigned int i;
590: for (i = 0; i < len; i++) {
591: unsigned char ch;
592: /* Get one character at a time. */
593: ch = buf[i];
594:
595: if (escape_pending) {
596: /* We have previously seen an escape character. */
597: /* Clear the flag now. */
598: escape_pending = 0;
599: /* Process the escaped character. */
600: switch (ch) {
601: case '.':
602: /* Terminate the connection. */
603: snprintf(buf, sizeof buf, "%c.\r\n", escape_char);
604: buffer_append(&stderr_buffer, buf, strlen(buf));
605: stderr_bytes += strlen(buf);
606: quit_pending = 1;
607: return;
608:
609: case 'Z' - 64:
610: /* Suspend the program. */
611: /* Print a message to that effect to the user. */
612: snprintf(buf, sizeof buf, "%c^Z\r\n", escape_char);
613: buffer_append(&stderr_buffer, buf, strlen(buf));
614: stderr_bytes += strlen(buf);
615:
616: /* Restore terminal modes and suspend. */
617: client_suspend_self();
618:
619: /* We have been continued. */
620: continue;
621:
622: case '&':
1.13 ! markus 623: /*
! 624: * Detach the program (continue to serve connections,
! 625: * but put in background and no more new connections).
! 626: */
1.11 markus 627: if (!stdin_eof) {
1.13 ! markus 628: /*
! 629: * Sending SSH_CMSG_EOF alone does not always appear
! 630: * to be enough. So we try to send an EOF character
! 631: * first.
! 632: */
1.11 markus 633: packet_start(SSH_CMSG_STDIN_DATA);
634: packet_put_string("\004", 1);
635: packet_send();
636: /* Close stdin. */
637: stdin_eof = 1;
638: if (buffer_len(&stdin_buffer) == 0) {
639: packet_start(SSH_CMSG_EOF);
640: packet_send();
641: }
642: }
643: /* Restore tty modes. */
644: leave_raw_mode();
645:
646: /* Stop listening for new connections. */
647: channel_stop_listening();
648:
649: printf("%c& [backgrounded]\n", escape_char);
650:
651: /* Fork into background. */
652: pid = fork();
653: if (pid < 0) {
654: error("fork: %.100s", strerror(errno));
655: continue;
656: }
657: if (pid != 0) { /* This is the parent. */
658: /* The parent just exits. */
659: exit(0);
660: }
661: /* The child continues serving connections. */
662: continue;
663:
664: case '?':
665: snprintf(buf, sizeof buf,
666: "%c?\r\n\
1.1 deraadt 667: Supported escape sequences:\r\n\
668: ~. - terminate connection\r\n\
669: ~^Z - suspend ssh\r\n\
670: ~# - list forwarded connections\r\n\
671: ~& - background ssh (when waiting for connections to terminate)\r\n\
672: ~? - this message\r\n\
673: ~~ - send the escape character by typing it twice\r\n\
674: (Note that escapes are only recognized immediately after newline.)\r\n",
1.11 markus 675: escape_char);
676: buffer_append(&stderr_buffer, buf, strlen(buf));
677: continue;
678:
679: case '#':
680: snprintf(buf, sizeof buf, "%c#\r\n", escape_char);
681: buffer_append(&stderr_buffer, buf, strlen(buf));
682: s = channel_open_message();
683: buffer_append(&stderr_buffer, s, strlen(s));
684: xfree(s);
685: continue;
686:
687: default:
688: if (ch != escape_char) {
1.13 ! markus 689: /*
! 690: * Escape character followed by non-special character.
! 691: * Append both to the input buffer.
! 692: */
1.11 markus 693: buf[0] = escape_char;
694: buf[1] = ch;
695: buffer_append(&stdin_buffer, buf, 2);
696: stdin_bytes += 2;
697: continue;
698: }
1.13 ! markus 699: /*
! 700: * Note that escape character typed twice
! 701: * falls through here; the latter gets processed
! 702: * as a normal character below.
! 703: */
1.11 markus 704: break;
705: }
706: } else {
1.13 ! markus 707: /*
! 708: * The previous character was not an escape char. Check if this
! 709: * is an escape.
! 710: */
1.11 markus 711: if (last_was_cr && ch == escape_char) {
712: /* It is. Set the flag and continue to next character. */
713: escape_pending = 1;
714: continue;
715: }
716: }
717:
1.13 ! markus 718: /*
! 719: * Normal character. Record whether it was a newline,
! 720: * and append it to the buffer.
! 721: */
1.11 markus 722: last_was_cr = (ch == '\r' || ch == '\n');
723: buf[0] = ch;
724: buffer_append(&stdin_buffer, buf, 1);
725: stdin_bytes += 1;
726: continue;
727: }
728: }
729: }
730: }
731:
732: void
733: client_process_output(fd_set * writeset)
734: {
735: int len;
736: char buf[100];
1.1 deraadt 737:
1.11 markus 738: /* Write buffered output to stdout. */
739: if (FD_ISSET(fileno(stdout), writeset)) {
740: /* Write as much data as possible. */
741: len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
742: buffer_len(&stdout_buffer));
743: if (len <= 0) {
744: if (errno == EAGAIN)
745: len = 0;
746: else {
1.13 ! markus 747: /*
! 748: * An error or EOF was encountered. Put an
! 749: * error message to stderr buffer.
! 750: */
1.11 markus 751: snprintf(buf, sizeof buf, "write stdout: %.50s\r\n", strerror(errno));
752: buffer_append(&stderr_buffer, buf, strlen(buf));
753: stderr_bytes += strlen(buf);
754: quit_pending = 1;
755: return;
756: }
757: }
758: /* Consume printed data from the buffer. */
759: buffer_consume(&stdout_buffer, len);
760: }
761: /* Write buffered output to stderr. */
762: if (FD_ISSET(fileno(stderr), writeset)) {
763: /* Write as much data as possible. */
764: len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
765: buffer_len(&stderr_buffer));
766: if (len <= 0) {
767: if (errno == EAGAIN)
768: len = 0;
769: else {
1.13 ! markus 770: /* EOF or error, but can't even print error message. */
1.11 markus 771: quit_pending = 1;
772: return;
773: }
774: }
775: /* Consume printed characters from the buffer. */
776: buffer_consume(&stderr_buffer, len);
777: }
1.1 deraadt 778: }
779:
1.13 ! markus 780: /*
! 781: * Implements the interactive session with the server. This is called after
! 782: * the user has been authenticated, and a command has been started on the
! 783: * remote host. If escape_char != -1, it is the character used as an escape
! 784: * character for terminating or suspending the session.
! 785: */
1.1 deraadt 786:
1.11 markus 787: int
788: client_loop(int have_pty, int escape_char_arg)
1.1 deraadt 789: {
1.11 markus 790: extern Options options;
791: double start_time, total_time;
792: int len;
793: char buf[100];
794:
795: debug("Entering interactive session.");
796:
797: start_time = get_current_time();
798:
799: /* Initialize variables. */
800: escape_pending = 0;
801: last_was_cr = 1;
802: exit_status = -1;
803: stdin_eof = 0;
804: buffer_high = 64 * 1024;
805: connection_in = packet_get_connection_in();
806: connection_out = packet_get_connection_out();
807: max_fd = connection_in;
808: if (connection_out > max_fd)
809: max_fd = connection_out;
810: stdin_bytes = 0;
811: stdout_bytes = 0;
812: stderr_bytes = 0;
813: quit_pending = 0;
814: escape_char = escape_char_arg;
815:
816: /* Initialize buffers. */
817: buffer_init(&stdin_buffer);
818: buffer_init(&stdout_buffer);
819: buffer_init(&stderr_buffer);
820:
821: /* Set signal handlers to restore non-blocking mode. */
822: signal(SIGINT, signal_handler);
823: signal(SIGQUIT, signal_handler);
824: signal(SIGTERM, signal_handler);
825: signal(SIGPIPE, SIG_IGN);
826: if (have_pty)
827: signal(SIGWINCH, window_change_handler);
828:
829: if (have_pty)
830: enter_raw_mode();
831:
832: /* Check if we should immediately send of on stdin. */
833: client_check_initial_eof_on_stdin();
834:
835: /* Main loop of the client for the interactive session mode. */
836: while (!quit_pending) {
837: fd_set readset, writeset;
838:
1.13 ! markus 839: /* Process buffered packets sent by the server. */
1.11 markus 840: client_process_buffered_input_packets();
841:
1.13 ! markus 842: /*
! 843: * Make packets of buffered stdin data, and buffer them for
! 844: * sending to the server.
! 845: */
1.11 markus 846: client_make_packets_from_stdin_data();
847:
1.13 ! markus 848: /*
! 849: * Make packets from buffered channel data, and buffer them
! 850: * for sending to the server.
! 851: */
1.11 markus 852: if (packet_not_very_much_data_to_write())
853: channel_output_poll();
854:
1.13 ! markus 855: /*
! 856: * Check if the window size has changed, and buffer a message
! 857: * about it to the server if so.
! 858: */
1.11 markus 859: client_check_window_change();
860:
861: if (quit_pending)
862: break;
863:
1.13 ! markus 864: /*
! 865: * Wait until we have something to do (something becomes
! 866: * available on one of the descriptors).
! 867: */
1.11 markus 868: client_wait_until_can_do_something(&readset, &writeset);
869:
870: if (quit_pending)
871: break;
872:
873: /* Do channel operations. */
874: channel_after_select(&readset, &writeset);
875:
1.13 ! markus 876: /*
! 877: * Process input from the connection and from stdin. Buffer
! 878: * any data that is available.
! 879: */
1.11 markus 880: client_process_input(&readset);
881:
1.13 ! markus 882: /*
! 883: * Process output to stdout and stderr. Output to the
! 884: * connection is processed elsewhere (above).
! 885: */
1.11 markus 886: client_process_output(&writeset);
887:
1.13 ! markus 888: /* Send as much buffered packet data as possible to the sender. */
1.11 markus 889: if (FD_ISSET(connection_out, &writeset))
890: packet_write_poll();
891: }
892:
893: /* Terminate the session. */
894:
895: /* Stop watching for window change. */
896: if (have_pty)
897: signal(SIGWINCH, SIG_DFL);
898:
899: /* Stop listening for connections. */
900: channel_stop_listening();
901:
1.13 ! markus 902: /*
! 903: * In interactive mode (with pseudo tty) display a message indicating
! 904: * that the connection has been closed.
! 905: */
1.11 markus 906: if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
907: snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host);
908: buffer_append(&stderr_buffer, buf, strlen(buf));
909: stderr_bytes += strlen(buf);
910: }
911: /* Output any buffered data for stdout. */
912: while (buffer_len(&stdout_buffer) > 0) {
913: len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
914: buffer_len(&stdout_buffer));
915: if (len <= 0) {
916: error("Write failed flushing stdout buffer.");
917: break;
918: }
919: buffer_consume(&stdout_buffer, len);
920: }
921:
922: /* Output any buffered data for stderr. */
923: while (buffer_len(&stderr_buffer) > 0) {
924: len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
925: buffer_len(&stderr_buffer));
926: if (len <= 0) {
927: error("Write failed flushing stderr buffer.");
928: break;
929: }
930: buffer_consume(&stderr_buffer, len);
931: }
932:
933: if (have_pty)
934: leave_raw_mode();
935:
936: /* Clear and free any buffers. */
937: memset(buf, 0, sizeof(buf));
938: buffer_free(&stdin_buffer);
939: buffer_free(&stdout_buffer);
940: buffer_free(&stderr_buffer);
941:
942: /* Report bytes transferred, and transfer rates. */
943: total_time = get_current_time() - start_time;
944: debug("Transferred: stdin %lu, stdout %lu, stderr %lu bytes in %.1f seconds",
945: stdin_bytes, stdout_bytes, stderr_bytes, total_time);
946: if (total_time > 0)
947: debug("Bytes per second: stdin %.1f, stdout %.1f, stderr %.1f",
948: stdin_bytes / total_time, stdout_bytes / total_time,
949: stderr_bytes / total_time);
950:
951: /* Return the exit status of the program. */
952: debug("Exit status %d", exit_status);
953: return exit_status;
1.1 deraadt 954: }
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