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1/* $OpenBSD: ttymodes.c,v 1.37 2026/02/14 00:18:34 jsg 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 <sys/types.h>
47
48#include <errno.h>
49#include <string.h>
50#include <termios.h>
51#include <stdarg.h>
52
53#include "packet.h"
54#include "log.h"
55#include "compat.h"
56#include "sshbuf.h"
57
58#define TTY_OP_END 0
59/*
60 * uint32 (u_int) follows speed.
61 */
62#define TTY_OP_ISPEED 128
63#define TTY_OP_OSPEED 129
64
65/*
66 * Converts POSIX speed_t to a baud rate. The values of the
67 * constants for speed_t are not themselves portable.
68 */
69static int
70speed_to_baud(speed_t speed)
71{
72 switch (speed) {
73 case B0:
74 return 0;
75 case B50:
76 return 50;
77 case B75:
78 return 75;
79 case B110:
80 return 110;
81 case B134:
82 return 134;
83 case B150:
84 return 150;
85 case B200:
86 return 200;
87 case B300:
88 return 300;
89 case B600:
90 return 600;
91 case B1200:
92 return 1200;
93 case B1800:
94 return 1800;
95 case B2400:
96 return 2400;
97 case B4800:
98 return 4800;
99 case B9600:
100 return 9600;
101
102#ifdef B19200
103 case B19200:
104 return 19200;
105#else /* B19200 */
106#ifdef EXTA
107 case EXTA:
108 return 19200;
109#endif /* EXTA */
110#endif /* B19200 */
111
112#ifdef B38400
113 case B38400:
114 return 38400;
115#else /* B38400 */
116#ifdef EXTB
117 case EXTB:
118 return 38400;
119#endif /* EXTB */
120#endif /* B38400 */
121
122#ifdef B7200
123 case B7200:
124 return 7200;
125#endif /* B7200 */
126#ifdef B14400
127 case B14400:
128 return 14400;
129#endif /* B14400 */
130#ifdef B28800
131 case B28800:
132 return 28800;
133#endif /* B28800 */
134#ifdef B57600
135 case B57600:
136 return 57600;
137#endif /* B57600 */
138#ifdef B76800
139 case B76800:
140 return 76800;
141#endif /* B76800 */
142#ifdef B115200
143 case B115200:
144 return 115200;
145#endif /* B115200 */
146#ifdef B230400
147 case B230400:
148 return 230400;
149#endif /* B230400 */
150 default:
151 return 9600;
152 }
153}
154
155/*
156 * Converts a numeric baud rate to a POSIX speed_t.
157 */
158static speed_t
159baud_to_speed(int baud)
160{
161 switch (baud) {
162 case 0:
163 return B0;
164 case 50:
165 return B50;
166 case 75:
167 return B75;
168 case 110:
169 return B110;
170 case 134:
171 return B134;
172 case 150:
173 return B150;
174 case 200:
175 return B200;
176 case 300:
177 return B300;
178 case 600:
179 return B600;
180 case 1200:
181 return B1200;
182 case 1800:
183 return B1800;
184 case 2400:
185 return B2400;
186 case 4800:
187 return B4800;
188 case 9600:
189 return B9600;
190
191#ifdef B19200
192 case 19200:
193 return B19200;
194#else /* B19200 */
195#ifdef EXTA
196 case 19200:
197 return EXTA;
198#endif /* EXTA */
199#endif /* B19200 */
200
201#ifdef B38400
202 case 38400:
203 return B38400;
204#else /* B38400 */
205#ifdef EXTB
206 case 38400:
207 return EXTB;
208#endif /* EXTB */
209#endif /* B38400 */
210
211#ifdef B7200
212 case 7200:
213 return B7200;
214#endif /* B7200 */
215#ifdef B14400
216 case 14400:
217 return B14400;
218#endif /* B14400 */
219#ifdef B28800
220 case 28800:
221 return B28800;
222#endif /* B28800 */
223#ifdef B57600
224 case 57600:
225 return B57600;
226#endif /* B57600 */
227#ifdef B76800
228 case 76800:
229 return B76800;
230#endif /* B76800 */
231#ifdef B115200
232 case 115200:
233 return B115200;
234#endif /* B115200 */
235#ifdef B230400
236 case 230400:
237 return B230400;
238#endif /* B230400 */
239 default:
240 return B9600;
241 }
242}
243
244/*
245 * Encodes terminal modes for the terminal referenced by fd
246 * or tiop in a portable manner, and appends the modes to a packet
247 * being constructed.
248 */
249void
250ssh_tty_make_modes(struct ssh *ssh, int fd, struct termios *tiop)
251{
252 struct termios tio;
253 struct sshbuf *buf;
254 int r, ibaud, obaud;
255
256 if ((buf = sshbuf_new()) == NULL)
257 fatal_f("sshbuf_new failed");
258
259 if (tiop == NULL) {
260 if (fd == -1) {
261 debug_f("no fd or tio");
262 goto end;
263 }
264 if (tcgetattr(fd, &tio) == -1) {
265 logit("tcgetattr: %.100s", strerror(errno));
266 goto end;
267 }
268 } else
269 tio = *tiop;
270
271 /* Store input and output baud rates. */
272 obaud = speed_to_baud(cfgetospeed(&tio));
273 ibaud = speed_to_baud(cfgetispeed(&tio));
274 if ((r = sshbuf_put_u8(buf, TTY_OP_OSPEED)) != 0 ||
275 (r = sshbuf_put_u32(buf, obaud)) != 0 ||
276 (r = sshbuf_put_u8(buf, TTY_OP_ISPEED)) != 0 ||
277 (r = sshbuf_put_u32(buf, ibaud)) != 0)
278 fatal_fr(r, "compose");
279
280 /* Store values of mode flags. */
281#define TTYCHAR(NAME, OP) \
282 if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
283 (r = sshbuf_put_u32(buf, tio.c_cc[NAME])) != 0) \
284 fatal_fr(r, "compose %s", #NAME);
285
286#define SSH_TTYMODE_IUTF8 42 /* for SSH_BUG_UTF8TTYMODE */
287
288#define TTYMODE(NAME, FIELD, OP) \
289 if (OP == SSH_TTYMODE_IUTF8 && (ssh->compat & SSH_BUG_UTF8TTYMODE)) { \
290 debug3_f("SSH_BUG_UTF8TTYMODE"); \
291 } else if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
292 (r = sshbuf_put_u32(buf, ((tio.FIELD & NAME) != 0))) != 0) \
293 fatal_fr(r, "compose %s", #NAME);
294
295#include "ttymodes.h"
296
297#undef TTYCHAR
298#undef TTYMODE
299
300end:
301 /* Mark end of mode data. */
302 if ((r = sshbuf_put_u8(buf, TTY_OP_END)) != 0 ||
303 (r = sshpkt_put_stringb(ssh, buf)) != 0)
304 fatal_fr(r, "compose end");
305 sshbuf_free(buf);
306}
307
308/*
309 * Decodes terminal modes for the terminal referenced by fd in a portable
310 * manner from a packet being read.
311 */
312void
313ssh_tty_parse_modes(struct ssh *ssh, int fd)
314{
315 struct termios tio;
316 struct sshbuf *buf;
317 const u_char *data;
318 u_char opcode;
319 u_int baud, u;
320 int r, failure = 0;
321 size_t len;
322
323 if ((r = sshpkt_get_string_direct(ssh, &data, &len)) != 0)
324 fatal_fr(r, "parse");
325 if (len == 0)
326 return;
327 if ((buf = sshbuf_from(data, len)) == NULL) {
328 error_f("sshbuf_from failed");
329 return;
330 }
331
332 /*
333 * Get old attributes for the terminal. We will modify these
334 * flags. I am hoping that if there are any machine-specific
335 * modes, they will initially have reasonable values.
336 */
337 if (tcgetattr(fd, &tio) == -1) {
338 logit("tcgetattr: %.100s", strerror(errno));
339 failure = -1;
340 }
341
342 while (sshbuf_len(buf) > 0) {
343 if ((r = sshbuf_get_u8(buf, &opcode)) != 0)
344 fatal_fr(r, "parse opcode");
345 switch (opcode) {
346 case TTY_OP_END:
347 goto set;
348
349 case TTY_OP_ISPEED:
350 if ((r = sshbuf_get_u32(buf, &baud)) != 0)
351 fatal_fr(r, "parse ispeed");
352 if (failure != -1 &&
353 cfsetispeed(&tio, baud_to_speed(baud)) == -1)
354 error("cfsetispeed failed for %d", baud);
355 break;
356
357 case TTY_OP_OSPEED:
358 if ((r = sshbuf_get_u32(buf, &baud)) != 0)
359 fatal_fr(r, "parse ospeed");
360 if (failure != -1 &&
361 cfsetospeed(&tio, baud_to_speed(baud)) == -1)
362 error("cfsetospeed failed for %d", baud);
363 break;
364
365#define TTYCHAR(NAME, OP) \
366 case OP: \
367 if ((r = sshbuf_get_u32(buf, &u)) != 0) \
368 fatal_fr(r, "parse %s", #NAME); \
369 tio.c_cc[NAME] = u; \
370 break;
371#define TTYMODE(NAME, FIELD, OP) \
372 case OP: \
373 if ((r = sshbuf_get_u32(buf, &u)) != 0) \
374 fatal_fr(r, "parse %s", #NAME); \
375 if (u) \
376 tio.FIELD |= NAME; \
377 else \
378 tio.FIELD &= ~NAME; \
379 break;
380
381#include "ttymodes.h"
382
383#undef TTYCHAR
384#undef TTYMODE
385
386 default:
387 debug("Ignoring unsupported tty mode opcode %d (0x%x)",
388 opcode, opcode);
389 /*
390 * SSH2:
391 * Opcodes 1 to 159 are defined to have a uint32
392 * argument.
393 * Opcodes 160 to 255 are undefined and cause parsing
394 * to stop.
395 */
396 if (opcode > 0 && opcode < 160) {
397 if ((r = sshbuf_get_u32(buf, NULL)) != 0)
398 fatal_fr(r, "parse arg");
399 break;
400 } else {
401 logit_f("unknown opcode %d", opcode);
402 goto set;
403 }
404 }
405 }
406
407set:
408 len = sshbuf_len(buf);
409 sshbuf_free(buf);
410 if (len > 0) {
411 logit_f("%zu bytes left", len);
412 return; /* Don't process bytes passed */
413 }
414 if (failure == -1)
415 return; /* Packet parsed ok but tcgetattr() failed */
416
417 /* Set the new modes for the terminal. */
418 if (tcsetattr(fd, TCSANOW, &tio) == -1)
419 logit("Setting tty modes failed: %.100s", strerror(errno));
420}