summaryrefslogtreecommitdiffhomepage
path: root/cli-chansession.c
blob: d3b14bb3f8337f98e78812dbd5a0fea185e0c139 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
/*
 * Dropbear SSH
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * Copyright (c) 2004 by Mihnea Stoenescu
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#include "includes.h"
#include "packet.h"
#include "buffer.h"
#include "session.h"
#include "dbutil.h"
#include "channel.h"
#include "ssh.h"
#include "runopts.h"
#include "termcodes.h"
#include "chansession.h"
#include "agentfwd.h"

static void cli_closechansess(struct Channel *channel);
static int cli_initchansess(struct Channel *channel);
static void cli_chansessreq(struct Channel *channel);
static void send_chansess_pty_req(struct Channel *channel);
static void send_chansess_shell_req(struct Channel *channel);
static void cli_escape_handler(struct Channel *channel, unsigned char* buf, int *len);


static void cli_tty_setup();

const struct ChanType clichansess = {
	0, /* sepfds */
	"session", /* name */
	cli_initchansess, /* inithandler */
	NULL, /* checkclosehandler */
	cli_chansessreq, /* reqhandler */
	cli_closechansess, /* closehandler */
};

static void cli_chansessreq(struct Channel *channel) {

	unsigned char* type = NULL;
	int wantreply;

	TRACE(("enter cli_chansessreq"))

	type = buf_getstring(ses.payload, NULL);
	wantreply = buf_getbool(ses.payload);

	if (strcmp(type, "exit-status") == 0) {
		cli_ses.retval = buf_getint(ses.payload);
		TRACE(("got exit-status of '%d'", cli_ses.retval))
	} else if (strcmp(type, "exit-signal") == 0) {
		TRACE(("got exit-signal, ignoring it"))
	} else {
		TRACE(("unknown request '%s'", type))
		send_msg_channel_failure(channel);
		goto out;
	}
		
out:
	m_free(type);
}
	

/* If the main session goes, we close it up */
static void cli_closechansess(struct Channel *UNUSED(channel)) {

	/* This channel hasn't gone yet, so we have > 1 */
	if (ses.chancount > 1) {
		dropbear_log(LOG_INFO, "Waiting for other channels to close...");
	}

	cli_tty_cleanup(); /* Restore tty modes etc */

}

void cli_start_send_channel_request(struct Channel *channel, 
		unsigned char *type) {

	CHECKCLEARTOWRITE();
	buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
	buf_putint(ses.writepayload, channel->remotechan);

	buf_putstring(ses.writepayload, type, strlen(type));

}

/* Taken from OpenSSH's sshtty.c:
 * RCSID("OpenBSD: sshtty.c,v 1.5 2003/09/19 17:43:35 markus Exp "); */
static void cli_tty_setup() {

	struct termios tio;

	TRACE(("enter cli_pty_setup"))

	if (cli_ses.tty_raw_mode == 1) {
		TRACE(("leave cli_tty_setup: already in raw mode!"))
		return;
	}

	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
		dropbear_exit("Failed to set raw TTY mode");
	}

	/* make a copy */
	cli_ses.saved_tio = tio;

	tio.c_iflag |= IGNPAR;
	tio.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
#ifdef IUCLC
	tio.c_iflag &= ~IUCLC;
#endif
	tio.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
#ifdef IEXTEN
	tio.c_lflag &= ~IEXTEN;
#endif
	tio.c_oflag &= ~OPOST;
	tio.c_cc[VMIN] = 1;
	tio.c_cc[VTIME] = 0;
	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &tio) == -1) {
		dropbear_exit("Failed to set raw TTY mode");
	}

	cli_ses.tty_raw_mode = 1;
	TRACE(("leave cli_tty_setup"))
}

void cli_tty_cleanup() {

	TRACE(("enter cli_tty_cleanup"))

	if (cli_ses.tty_raw_mode == 0) {
		TRACE(("leave cli_tty_cleanup: not in raw mode"))
		return;
	}

	if (tcsetattr(STDIN_FILENO, TCSADRAIN, &cli_ses.saved_tio) == -1) {
		dropbear_log(LOG_WARNING, "Failed restoring TTY");
	} else {
		cli_ses.tty_raw_mode = 0; 
	}

	TRACE(("leave cli_tty_cleanup"))
}

static void put_termcodes() {

	struct termios tio;
	unsigned int sshcode;
	const struct TermCode *termcode;
	unsigned int value;
	unsigned int mapcode;

	unsigned int bufpos1, bufpos2;

	TRACE(("enter put_termcodes"))

	if (tcgetattr(STDIN_FILENO, &tio) == -1) {
		dropbear_log(LOG_WARNING, "Failed reading termmodes");
		buf_putint(ses.writepayload, 1); /* Just the terminator */
		buf_putbyte(ses.writepayload, 0); /* TTY_OP_END */
		return;
	}

	bufpos1 = ses.writepayload->pos;
	buf_putint(ses.writepayload, 0); /* A placeholder for the final length */

	/* As with Dropbear server, we ignore baud rates for now */
	for (sshcode = 1; sshcode < MAX_TERMCODE; sshcode++) {

		termcode = &termcodes[sshcode];
		mapcode = termcode->mapcode;

		switch (termcode->type) {

			case TERMCODE_NONE:
				continue;

			case TERMCODE_CONTROLCHAR:
				value = tio.c_cc[mapcode];
				break;

			case TERMCODE_INPUT:
				value = tio.c_iflag & mapcode;
				break;

			case TERMCODE_OUTPUT:
				value = tio.c_oflag & mapcode;
				break;

			case TERMCODE_LOCAL:
				value = tio.c_lflag & mapcode;
				break;

			case TERMCODE_CONTROL:
				value = tio.c_cflag & mapcode;
				break;

			default:
				continue;

		}

		/* If we reach here, we have something to say */
		buf_putbyte(ses.writepayload, sshcode);
		buf_putint(ses.writepayload, value);
	}

	buf_putbyte(ses.writepayload, 0); /* THE END, aka TTY_OP_END */

	/* Put the string length at the start of the buffer */
	bufpos2 = ses.writepayload->pos;

	buf_setpos(ses.writepayload, bufpos1); /* Jump back */
	buf_putint(ses.writepayload, bufpos2 - bufpos1 - 4); /* len(termcodes) */
	buf_setpos(ses.writepayload, bufpos2); /* Back where we were */

	TRACE(("leave put_termcodes"))
}

static void put_winsize() {

	struct winsize ws;

	if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0) {
		/* Some sane defaults */
		ws.ws_row = 25;
		ws.ws_col = 80;
		ws.ws_xpixel = 0;
		ws.ws_ypixel = 0;
	}

	buf_putint(ses.writepayload, ws.ws_col); /* Cols */
	buf_putint(ses.writepayload, ws.ws_row); /* Rows */
	buf_putint(ses.writepayload, ws.ws_xpixel); /* Width */
	buf_putint(ses.writepayload, ws.ws_ypixel); /* Height */

}

static void sigwinch_handler(int UNUSED(unused)) {

	cli_ses.winchange = 1;

}

void cli_chansess_winchange() {

	unsigned int i;
	struct Channel *channel = NULL;

	for (i = 0; i < ses.chansize; i++) {
		channel = ses.channels[i];
		if (channel != NULL && channel->type == &clichansess) {
			CHECKCLEARTOWRITE();
			buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_REQUEST);
			buf_putint(ses.writepayload, channel->remotechan);
			buf_putstring(ses.writepayload, "window-change", 13);
			buf_putbyte(ses.writepayload, 0); /* FALSE says the spec */
			put_winsize();
			encrypt_packet();
		}
	}
	cli_ses.winchange = 0;
}

static void send_chansess_pty_req(struct Channel *channel) {

	unsigned char* term = NULL;

	TRACE(("enter send_chansess_pty_req"))

	cli_start_send_channel_request(channel, "pty-req");

	/* Don't want replies */
	buf_putbyte(ses.writepayload, 0);

	/* Get the terminal */
	term = getenv("TERM");
	if (term == NULL) {
		term = "vt100"; /* Seems a safe default */
	}
	buf_putstring(ses.writepayload, term, strlen(term));

	/* Window size */
	put_winsize();

	/* Terminal mode encoding */
	put_termcodes();

	encrypt_packet();

	/* Set up a window-change handler */
	if (signal(SIGWINCH, sigwinch_handler) == SIG_ERR) {
		dropbear_exit("Signal error");
	}
	TRACE(("leave send_chansess_pty_req"))
}

static void send_chansess_shell_req(struct Channel *channel) {

	unsigned char* reqtype = NULL;

	TRACE(("enter send_chansess_shell_req"))

	if (cli_opts.cmd) {
		if (cli_opts.is_subsystem) {
			reqtype = "subsystem";
		} else {
			reqtype = "exec";
		}
	} else {
		reqtype = "shell";
	}

	cli_start_send_channel_request(channel, reqtype);

	/* XXX TODO */
	buf_putbyte(ses.writepayload, 0); /* Don't want replies */
	if (cli_opts.cmd) {
		buf_putstring(ses.writepayload, cli_opts.cmd, strlen(cli_opts.cmd));
	}

	encrypt_packet();
	TRACE(("leave send_chansess_shell_req"))
}

/* Shared for normal client channel and netcat-alike */
static int cli_init_stdpipe_sess(struct Channel *channel) {
	channel->writefd = STDOUT_FILENO;
	setnonblocking(STDOUT_FILENO);

	channel->readfd = STDIN_FILENO;
	setnonblocking(STDIN_FILENO);

	channel->errfd = STDERR_FILENO;
	setnonblocking(STDERR_FILENO);

	channel->extrabuf = cbuf_new(opts.recv_window);
	return 0;
}

static int cli_initchansess(struct Channel *channel) {

	cli_init_stdpipe_sess(channel);

#ifdef ENABLE_CLI_AGENTFWD
	if (cli_opts.agent_fwd) {
		cli_setup_agent(channel);
	}
#endif

	if (cli_opts.wantpty) {
		send_chansess_pty_req(channel);
	}

	send_chansess_shell_req(channel);

	if (cli_opts.wantpty) {
		cli_tty_setup();
		channel->read_mangler = cli_escape_handler;
		cli_ses.last_char = '\r';
	}	

	return 0; /* Success */
}

#ifdef ENABLE_CLI_NETCAT

static const struct ChanType cli_chan_netcat = {
	0, /* sepfds */
	"direct-tcpip",
	cli_init_stdpipe_sess, /* inithandler */
	NULL,
	NULL,
	cli_closechansess
};

void cli_send_netcat_request() {

	const unsigned char* source_host = "127.0.0.1";
	const int source_port = 22;

	cli_opts.wantpty = 0;

	if (send_msg_channel_open_init(STDIN_FILENO, &cli_chan_netcat) 
			== DROPBEAR_FAILURE) {
		dropbear_exit("Couldn't open initial channel");
	}

	buf_putstring(ses.writepayload, cli_opts.netcat_host, 
			strlen(cli_opts.netcat_host));
	buf_putint(ses.writepayload, cli_opts.netcat_port);

	/* originator ip - localhost is accurate enough */
	buf_putstring(ses.writepayload, source_host, strlen(source_host));
	buf_putint(ses.writepayload, source_port);

	encrypt_packet();
	TRACE(("leave cli_send_chansess_request"))
}
#endif

void cli_send_chansess_request() {

	TRACE(("enter cli_send_chansess_request"))

	if (send_msg_channel_open_init(STDIN_FILENO, &clichansess) 
			== DROPBEAR_FAILURE) {
		dropbear_exit("Couldn't open initial channel");
	}

	/* No special channel request data */
	encrypt_packet();
	TRACE(("leave cli_send_chansess_request"))

}

// returns 1 if the character should be consumed, 0 to pass through
static int
do_escape(unsigned char c) {
	switch (c) {
		case '.':
			dropbear_exit("Terminated");
			return 1;
			break;
		case 0x1a:
			// ctrl-z
			cli_tty_cleanup();
			kill(getpid(), SIGTSTP);
			// after continuation
			cli_tty_setup();
			cli_ses.winchange = 1;
			return 1;
			break;
	}
	return 0;
}

static
void cli_escape_handler(struct Channel* UNUSED(channel), unsigned char* buf, int *len) {
	char c;
	int skip_char = 0;

	// only handle escape characters if they are read one at a time. simplifies
	// the code and avoids nasty people putting ~. at the start of a line to paste 
	if (*len != 1) {
		cli_ses.last_char = 0x0;
		return;
	}

	c = buf[0];

	if (cli_ses.last_char == DROPBEAR_ESCAPE_CHAR) {
		skip_char = do_escape(c);
		cli_ses.last_char = 0x0;
	} else {
		if (c == DROPBEAR_ESCAPE_CHAR) {
			if (cli_ses.last_char == '\r') {
				cli_ses.last_char = DROPBEAR_ESCAPE_CHAR;
				skip_char = 1;
			} else {
				cli_ses.last_char = 0x0;
			}
		} else {
			cli_ses.last_char = c;
		}
	}

	if (skip_char) {
		*len = 0;
	}
}