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1 /* $OpenBSD: ttymodes.c,v 1.30 2016/05/04 14:22:33 markus Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
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 /*
15  * SSH2 tty modes support by Kevin Steves.
16  * Copyright (c) 2001 Kevin Steves.  All rights reserved.
17  *
18  * Redistribution and use in source and binary forms, with or without
19  * modification, are permitted provided that the following conditions
20  * are met:
21  * 1. Redistributions of source code must retain the above copyright
22  *    notice, this list of conditions and the following disclaimer.
23  * 2. Redistributions in binary form must reproduce the above copyright
24  *    notice, this list of conditions and the following disclaimer in the
25  *    documentation and/or other materials provided with the distribution.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Encoding and decoding of terminal modes in a portable way.
41  * Much of the format is defined in ttymodes.h; it is included multiple times
42  * into this file with the appropriate macro definitions to generate the
43  * suitable code.
44  */
45 
46 #include "includes.h"
47 
48 #include <sys/types.h>
49 
50 #include <errno.h>
51 #include <string.h>
52 #include <termios.h>
53 #include <stdarg.h>
54 
55 #include "packet.h"
56 #include "log.h"
57 #include "compat.h"
58 #include "buffer.h"
59 
60 #define TTY_OP_END		0
61 /*
62  * uint32 (u_int) follows speed in SSH1 and SSH2
63  */
64 #define TTY_OP_ISPEED_PROTO1	192
65 #define TTY_OP_OSPEED_PROTO1	193
66 #define TTY_OP_ISPEED_PROTO2	128
67 #define TTY_OP_OSPEED_PROTO2	129
68 
69 /*
70  * Converts POSIX speed_t to a baud rate.  The values of the
71  * constants for speed_t are not themselves portable.
72  */
73 static int
speed_to_baud(speed_t speed)74 speed_to_baud(speed_t speed)
75 {
76 	switch (speed) {
77 	case B0:
78 		return 0;
79 	case B50:
80 		return 50;
81 	case B75:
82 		return 75;
83 	case B110:
84 		return 110;
85 	case B134:
86 		return 134;
87 	case B150:
88 		return 150;
89 	case B200:
90 		return 200;
91 	case B300:
92 		return 300;
93 	case B600:
94 		return 600;
95 	case B1200:
96 		return 1200;
97 	case B1800:
98 		return 1800;
99 	case B2400:
100 		return 2400;
101 	case B4800:
102 		return 4800;
103 	case B9600:
104 		return 9600;
105 
106 #ifdef B19200
107 	case B19200:
108 		return 19200;
109 #else /* B19200 */
110 #ifdef EXTA
111 	case EXTA:
112 		return 19200;
113 #endif /* EXTA */
114 #endif /* B19200 */
115 
116 #ifdef B38400
117 	case B38400:
118 		return 38400;
119 #else /* B38400 */
120 #ifdef EXTB
121 	case EXTB:
122 		return 38400;
123 #endif /* EXTB */
124 #endif /* B38400 */
125 
126 #ifdef B7200
127 	case B7200:
128 		return 7200;
129 #endif /* B7200 */
130 #ifdef B14400
131 	case B14400:
132 		return 14400;
133 #endif /* B14400 */
134 #ifdef B28800
135 	case B28800:
136 		return 28800;
137 #endif /* B28800 */
138 #ifdef B57600
139 	case B57600:
140 		return 57600;
141 #endif /* B57600 */
142 #ifdef B76800
143 	case B76800:
144 		return 76800;
145 #endif /* B76800 */
146 #ifdef B115200
147 	case B115200:
148 		return 115200;
149 #endif /* B115200 */
150 #ifdef B230400
151 	case B230400:
152 		return 230400;
153 #endif /* B230400 */
154 	default:
155 		return 9600;
156 	}
157 }
158 
159 /*
160  * Converts a numeric baud rate to a POSIX speed_t.
161  */
162 static speed_t
baud_to_speed(int baud)163 baud_to_speed(int baud)
164 {
165 	switch (baud) {
166 	case 0:
167 		return B0;
168 	case 50:
169 		return B50;
170 	case 75:
171 		return B75;
172 	case 110:
173 		return B110;
174 	case 134:
175 		return B134;
176 	case 150:
177 		return B150;
178 	case 200:
179 		return B200;
180 	case 300:
181 		return B300;
182 	case 600:
183 		return B600;
184 	case 1200:
185 		return B1200;
186 	case 1800:
187 		return B1800;
188 	case 2400:
189 		return B2400;
190 	case 4800:
191 		return B4800;
192 	case 9600:
193 		return B9600;
194 
195 #ifdef B19200
196 	case 19200:
197 		return B19200;
198 #else /* B19200 */
199 #ifdef EXTA
200 	case 19200:
201 		return EXTA;
202 #endif /* EXTA */
203 #endif /* B19200 */
204 
205 #ifdef B38400
206 	case 38400:
207 		return B38400;
208 #else /* B38400 */
209 #ifdef EXTB
210 	case 38400:
211 		return EXTB;
212 #endif /* EXTB */
213 #endif /* B38400 */
214 
215 #ifdef B7200
216 	case 7200:
217 		return B7200;
218 #endif /* B7200 */
219 #ifdef B14400
220 	case 14400:
221 		return B14400;
222 #endif /* B14400 */
223 #ifdef B28800
224 	case 28800:
225 		return B28800;
226 #endif /* B28800 */
227 #ifdef B57600
228 	case 57600:
229 		return B57600;
230 #endif /* B57600 */
231 #ifdef B76800
232 	case 76800:
233 		return B76800;
234 #endif /* B76800 */
235 #ifdef B115200
236 	case 115200:
237 		return B115200;
238 #endif /* B115200 */
239 #ifdef B230400
240 	case 230400:
241 		return B230400;
242 #endif /* B230400 */
243 	default:
244 		return B9600;
245 	}
246 }
247 
248 /*
249  * Encode a special character into SSH line format.
250  */
251 static u_int
special_char_encode(cc_t c)252 special_char_encode(cc_t c)
253 {
254 #ifdef _POSIX_VDISABLE
255 	if (c == _POSIX_VDISABLE)
256 		return 255;
257 #endif /* _POSIX_VDISABLE */
258 	return c;
259 }
260 
261 /*
262  * Decode a special character from SSH line format.
263  */
264 static cc_t
special_char_decode(u_int c)265 special_char_decode(u_int c)
266 {
267 #ifdef _POSIX_VDISABLE
268 	if (c == 255)
269 		return _POSIX_VDISABLE;
270 #endif /* _POSIX_VDISABLE */
271 	return c;
272 }
273 
274 /*
275  * Encodes terminal modes for the terminal referenced by fd
276  * or tiop in a portable manner, and appends the modes to a packet
277  * being constructed.
278  */
279 void
tty_make_modes(int fd,struct termios * tiop)280 tty_make_modes(int fd, struct termios *tiop)
281 {
282 	struct termios tio;
283 	int baud;
284 	Buffer buf;
285 	int tty_op_ospeed, tty_op_ispeed;
286 	void (*put_arg)(Buffer *, u_int);
287 
288 	buffer_init(&buf);
289 	if (compat20) {
290 		tty_op_ospeed = TTY_OP_OSPEED_PROTO2;
291 		tty_op_ispeed = TTY_OP_ISPEED_PROTO2;
292 		put_arg = buffer_put_int;
293 	} else {
294 		tty_op_ospeed = TTY_OP_OSPEED_PROTO1;
295 		tty_op_ispeed = TTY_OP_ISPEED_PROTO1;
296 		put_arg = (void (*)(Buffer *, u_int)) buffer_put_char;
297 	}
298 
299 	if (tiop == NULL) {
300 		if (fd == -1) {
301 			debug("tty_make_modes: no fd or tio");
302 			goto end;
303 		}
304 		if (tcgetattr(fd, &tio) == -1) {
305 			logit("tcgetattr: %.100s", strerror(errno));
306 			goto end;
307 		}
308 	} else
309 		tio = *tiop;
310 
311 	/* Store input and output baud rates. */
312 	baud = speed_to_baud(cfgetospeed(&tio));
313 	buffer_put_char(&buf, tty_op_ospeed);
314 	buffer_put_int(&buf, baud);
315 	baud = speed_to_baud(cfgetispeed(&tio));
316 	buffer_put_char(&buf, tty_op_ispeed);
317 	buffer_put_int(&buf, baud);
318 
319 	/* Store values of mode flags. */
320 #define TTYCHAR(NAME, OP) \
321 	buffer_put_char(&buf, OP); \
322 	put_arg(&buf, special_char_encode(tio.c_cc[NAME]));
323 
324 #define TTYMODE(NAME, FIELD, OP) \
325 	buffer_put_char(&buf, OP); \
326 	put_arg(&buf, ((tio.FIELD & NAME) != 0));
327 
328 #include "ttymodes.h"
329 
330 #undef TTYCHAR
331 #undef TTYMODE
332 
333 end:
334 	/* Mark end of mode data. */
335 	buffer_put_char(&buf, TTY_OP_END);
336 	if (compat20)
337 		packet_put_string(buffer_ptr(&buf), buffer_len(&buf));
338 	else
339 		packet_put_raw(buffer_ptr(&buf), buffer_len(&buf));
340 	buffer_free(&buf);
341 }
342 
343 /*
344  * Decodes terminal modes for the terminal referenced by fd in a portable
345  * manner from a packet being read.
346  */
347 void
tty_parse_modes(int fd,int * n_bytes_ptr)348 tty_parse_modes(int fd, int *n_bytes_ptr)
349 {
350 	struct termios tio;
351 	int opcode, baud;
352 	int n_bytes = 0;
353 	int failure = 0;
354 	u_int (*get_arg)(void);
355 	int arg_size;
356 
357 	if (compat20) {
358 		*n_bytes_ptr = packet_get_int();
359 		if (*n_bytes_ptr == 0)
360 			return;
361 		get_arg = packet_get_int;
362 		arg_size = 4;
363 	} else {
364 		get_arg = packet_get_char;
365 		arg_size = 1;
366 	}
367 
368 	/*
369 	 * Get old attributes for the terminal.  We will modify these
370 	 * flags. I am hoping that if there are any machine-specific
371 	 * modes, they will initially have reasonable values.
372 	 */
373 	if (tcgetattr(fd, &tio) == -1) {
374 		logit("tcgetattr: %.100s", strerror(errno));
375 		failure = -1;
376 	}
377 
378 	for (;;) {
379 		n_bytes += 1;
380 		opcode = packet_get_char();
381 		switch (opcode) {
382 		case TTY_OP_END:
383 			goto set;
384 
385 		/* XXX: future conflict possible */
386 		case TTY_OP_ISPEED_PROTO1:
387 		case TTY_OP_ISPEED_PROTO2:
388 			n_bytes += 4;
389 			baud = packet_get_int();
390 			if (failure != -1 &&
391 			    cfsetispeed(&tio, baud_to_speed(baud)) == -1)
392 				error("cfsetispeed failed for %d", baud);
393 			break;
394 
395 		/* XXX: future conflict possible */
396 		case TTY_OP_OSPEED_PROTO1:
397 		case TTY_OP_OSPEED_PROTO2:
398 			n_bytes += 4;
399 			baud = packet_get_int();
400 			if (failure != -1 &&
401 			    cfsetospeed(&tio, baud_to_speed(baud)) == -1)
402 				error("cfsetospeed failed for %d", baud);
403 			break;
404 
405 #define TTYCHAR(NAME, OP) \
406 	case OP: \
407 	  n_bytes += arg_size; \
408 	  tio.c_cc[NAME] = special_char_decode(get_arg()); \
409 	  break;
410 #define TTYMODE(NAME, FIELD, OP) \
411 	case OP: \
412 	  n_bytes += arg_size; \
413 	  if (get_arg()) \
414 	    tio.FIELD |= NAME; \
415 	  else \
416 	    tio.FIELD &= ~NAME;	\
417 	  break;
418 
419 #include "ttymodes.h"
420 
421 #undef TTYCHAR
422 #undef TTYMODE
423 
424 		default:
425 			debug("Ignoring unsupported tty mode opcode %d (0x%x)",
426 			    opcode, opcode);
427 			if (!compat20) {
428 				/*
429 				 * SSH1:
430 				 * Opcodes 1 to 127 are defined to have
431 				 * a one-byte argument.
432 				 * Opcodes 128 to 159 are defined to have
433 				 * an integer argument.
434 				 */
435 				if (opcode > 0 && opcode < 128) {
436 					n_bytes += 1;
437 					(void) packet_get_char();
438 					break;
439 				} else if (opcode >= 128 && opcode < 160) {
440 					n_bytes += 4;
441 					(void) packet_get_int();
442 					break;
443 				} else {
444 					/*
445 					 * It is a truly undefined opcode (160 to 255).
446 					 * We have no idea about its arguments.  So we
447 					 * must stop parsing.  Note that some data
448 					 * may be left in the packet; hopefully there
449 					 * is nothing more coming after the mode data.
450 					 */
451 					logit("parse_tty_modes: unknown opcode %d",
452 					    opcode);
453 					goto set;
454 				}
455 			} else {
456 				/*
457 				 * SSH2:
458 				 * Opcodes 1 to 159 are defined to have
459 				 * a uint32 argument.
460 				 * Opcodes 160 to 255 are undefined and
461 				 * cause parsing to stop.
462 				 */
463 				if (opcode > 0 && opcode < 160) {
464 					n_bytes += 4;
465 					(void) packet_get_int();
466 					break;
467 				} else {
468 					logit("parse_tty_modes: unknown opcode %d",
469 					    opcode);
470 					goto set;
471 				}
472 			}
473 		}
474 	}
475 
476 set:
477 	if (*n_bytes_ptr != n_bytes) {
478 		*n_bytes_ptr = n_bytes;
479 		logit("parse_tty_modes: n_bytes_ptr != n_bytes: %d %d",
480 		    *n_bytes_ptr, n_bytes);
481 		return;		/* Don't process bytes passed */
482 	}
483 	if (failure == -1)
484 		return;		/* Packet parsed ok but tcgetattr() failed */
485 
486 	/* Set the new modes for the terminal. */
487 	if (tcsetattr(fd, TCSANOW, &tio) == -1)
488 		logit("Setting tty modes failed: %.100s", strerror(errno));
489 }
490