Line data Source code
1 : /* SPDX-License-Identifier: LGPL-2.1+ */
2 :
3 : #include <errno.h>
4 : #include <limits.h>
5 : #include <signal.h>
6 : #include <stddef.h>
7 : #include <stdint.h>
8 : #include <stdlib.h>
9 : #include <string.h>
10 : #include <sys/epoll.h>
11 : #include <sys/ioctl.h>
12 : #include <sys/time.h>
13 : #include <termios.h>
14 : #include <unistd.h>
15 :
16 : #include "sd-event.h"
17 :
18 : #include "alloc-util.h"
19 : #include "fd-util.h"
20 : #include "log.h"
21 : #include "macro.h"
22 : #include "ptyfwd.h"
23 : #include "terminal-util.h"
24 : #include "time-util.h"
25 :
26 : struct PTYForward {
27 : sd_event *event;
28 :
29 : int master;
30 :
31 : PTYForwardFlags flags;
32 :
33 : sd_event_source *stdin_event_source;
34 : sd_event_source *stdout_event_source;
35 : sd_event_source *master_event_source;
36 :
37 : sd_event_source *sigwinch_event_source;
38 :
39 : struct termios saved_stdin_attr;
40 : struct termios saved_stdout_attr;
41 :
42 : bool saved_stdin:1;
43 : bool saved_stdout:1;
44 :
45 : bool stdin_readable:1;
46 : bool stdin_hangup:1;
47 : bool stdout_writable:1;
48 : bool stdout_hangup:1;
49 : bool master_readable:1;
50 : bool master_writable:1;
51 : bool master_hangup:1;
52 :
53 : bool read_from_master:1;
54 :
55 : bool done:1;
56 : bool drain:1;
57 :
58 : bool last_char_set:1;
59 : char last_char;
60 :
61 : char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
62 : size_t in_buffer_full, out_buffer_full;
63 :
64 : usec_t escape_timestamp;
65 : unsigned escape_counter;
66 :
67 : PTYForwardHandler handler;
68 : void *userdata;
69 : };
70 :
71 : #define ESCAPE_USEC (1*USEC_PER_SEC)
72 :
73 0 : static void pty_forward_disconnect(PTYForward *f) {
74 :
75 0 : if (f) {
76 0 : f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
77 0 : f->stdout_event_source = sd_event_source_unref(f->stdout_event_source);
78 :
79 0 : f->master_event_source = sd_event_source_unref(f->master_event_source);
80 0 : f->sigwinch_event_source = sd_event_source_unref(f->sigwinch_event_source);
81 0 : f->event = sd_event_unref(f->event);
82 :
83 0 : if (f->saved_stdout)
84 0 : tcsetattr(STDOUT_FILENO, TCSANOW, &f->saved_stdout_attr);
85 0 : if (f->saved_stdin)
86 0 : tcsetattr(STDIN_FILENO, TCSANOW, &f->saved_stdin_attr);
87 :
88 0 : f->saved_stdout = f->saved_stdin = false;
89 : }
90 :
91 : /* STDIN/STDOUT should not be nonblocking normally, so let's unconditionally reset it */
92 0 : (void) fd_nonblock(STDIN_FILENO, false);
93 0 : (void) fd_nonblock(STDOUT_FILENO, false);
94 0 : }
95 :
96 0 : static int pty_forward_done(PTYForward *f, int rcode) {
97 0 : _cleanup_(sd_event_unrefp) sd_event *e = NULL;
98 0 : assert(f);
99 :
100 0 : if (f->done)
101 0 : return 0;
102 :
103 0 : e = sd_event_ref(f->event);
104 :
105 0 : f->done = true;
106 0 : pty_forward_disconnect(f);
107 :
108 0 : if (f->handler)
109 0 : return f->handler(f, rcode, f->userdata);
110 : else
111 0 : return sd_event_exit(e, rcode < 0 ? EXIT_FAILURE : rcode);
112 : }
113 :
114 0 : static bool look_for_escape(PTYForward *f, const char *buffer, size_t n) {
115 : const char *p;
116 :
117 0 : assert(f);
118 0 : assert(buffer);
119 0 : assert(n > 0);
120 :
121 0 : for (p = buffer; p < buffer + n; p++) {
122 :
123 : /* Check for ^] */
124 0 : if (*p == 0x1D) {
125 0 : usec_t nw = now(CLOCK_MONOTONIC);
126 :
127 0 : if (f->escape_counter == 0 || nw > f->escape_timestamp + ESCAPE_USEC) {
128 0 : f->escape_timestamp = nw;
129 0 : f->escape_counter = 1;
130 : } else {
131 0 : (f->escape_counter)++;
132 :
133 0 : if (f->escape_counter >= 3)
134 0 : return true;
135 : }
136 : } else {
137 0 : f->escape_timestamp = 0;
138 0 : f->escape_counter = 0;
139 : }
140 : }
141 :
142 0 : return false;
143 : }
144 :
145 0 : static bool ignore_vhangup(PTYForward *f) {
146 0 : assert(f);
147 :
148 0 : if (f->flags & PTY_FORWARD_IGNORE_VHANGUP)
149 0 : return true;
150 :
151 0 : if ((f->flags & PTY_FORWARD_IGNORE_INITIAL_VHANGUP) && !f->read_from_master)
152 0 : return true;
153 :
154 0 : return false;
155 : }
156 :
157 0 : static bool drained(PTYForward *f) {
158 0 : int q = 0;
159 :
160 0 : assert(f);
161 :
162 0 : if (f->out_buffer_full > 0)
163 0 : return false;
164 :
165 0 : if (f->master_readable)
166 0 : return false;
167 :
168 0 : if (ioctl(f->master, TIOCINQ, &q) < 0)
169 0 : log_debug_errno(errno, "TIOCINQ failed on master: %m");
170 0 : else if (q > 0)
171 0 : return false;
172 :
173 0 : if (ioctl(f->master, TIOCOUTQ, &q) < 0)
174 0 : log_debug_errno(errno, "TIOCOUTQ failed on master: %m");
175 0 : else if (q > 0)
176 0 : return false;
177 :
178 0 : return true;
179 : }
180 :
181 0 : static int shovel(PTYForward *f) {
182 : ssize_t k;
183 :
184 0 : assert(f);
185 :
186 0 : while ((f->stdin_readable && f->in_buffer_full <= 0) ||
187 0 : (f->master_writable && f->in_buffer_full > 0) ||
188 0 : (f->master_readable && f->out_buffer_full <= 0) ||
189 0 : (f->stdout_writable && f->out_buffer_full > 0)) {
190 :
191 0 : if (f->stdin_readable && f->in_buffer_full < LINE_MAX) {
192 :
193 0 : k = read(STDIN_FILENO, f->in_buffer + f->in_buffer_full, LINE_MAX - f->in_buffer_full);
194 0 : if (k < 0) {
195 :
196 0 : if (errno == EAGAIN)
197 0 : f->stdin_readable = false;
198 0 : else if (IN_SET(errno, EIO, EPIPE, ECONNRESET)) {
199 0 : f->stdin_readable = false;
200 0 : f->stdin_hangup = true;
201 :
202 0 : f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
203 : } else {
204 0 : log_error_errno(errno, "read(): %m");
205 0 : return pty_forward_done(f, -errno);
206 : }
207 0 : } else if (k == 0) {
208 : /* EOF on stdin */
209 0 : f->stdin_readable = false;
210 0 : f->stdin_hangup = true;
211 :
212 0 : f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
213 : } else {
214 : /* Check if ^] has been pressed three times within one second. If we get this we quite
215 : * immediately. */
216 0 : if (look_for_escape(f, f->in_buffer + f->in_buffer_full, k))
217 0 : return pty_forward_done(f, -ECANCELED);
218 :
219 0 : f->in_buffer_full += (size_t) k;
220 : }
221 : }
222 :
223 0 : if (f->master_writable && f->in_buffer_full > 0) {
224 :
225 0 : k = write(f->master, f->in_buffer, f->in_buffer_full);
226 0 : if (k < 0) {
227 :
228 0 : if (IN_SET(errno, EAGAIN, EIO))
229 0 : f->master_writable = false;
230 0 : else if (IN_SET(errno, EPIPE, ECONNRESET)) {
231 0 : f->master_writable = f->master_readable = false;
232 0 : f->master_hangup = true;
233 :
234 0 : f->master_event_source = sd_event_source_unref(f->master_event_source);
235 : } else {
236 0 : log_error_errno(errno, "write(): %m");
237 0 : return pty_forward_done(f, -errno);
238 : }
239 : } else {
240 0 : assert(f->in_buffer_full >= (size_t) k);
241 0 : memmove(f->in_buffer, f->in_buffer + k, f->in_buffer_full - k);
242 0 : f->in_buffer_full -= k;
243 : }
244 : }
245 :
246 0 : if (f->master_readable && f->out_buffer_full < LINE_MAX) {
247 :
248 0 : k = read(f->master, f->out_buffer + f->out_buffer_full, LINE_MAX - f->out_buffer_full);
249 0 : if (k < 0) {
250 :
251 : /* Note that EIO on the master device
252 : * might be caused by vhangup() or
253 : * temporary closing of everything on
254 : * the other side, we treat it like
255 : * EAGAIN here and try again, unless
256 : * ignore_vhangup is off. */
257 :
258 0 : if (errno == EAGAIN || (errno == EIO && ignore_vhangup(f)))
259 0 : f->master_readable = false;
260 0 : else if (IN_SET(errno, EPIPE, ECONNRESET, EIO)) {
261 0 : f->master_readable = f->master_writable = false;
262 0 : f->master_hangup = true;
263 :
264 0 : f->master_event_source = sd_event_source_unref(f->master_event_source);
265 : } else {
266 0 : log_error_errno(errno, "read(): %m");
267 0 : return pty_forward_done(f, -errno);
268 : }
269 : } else {
270 0 : f->read_from_master = true;
271 0 : f->out_buffer_full += (size_t) k;
272 : }
273 : }
274 :
275 0 : if (f->stdout_writable && f->out_buffer_full > 0) {
276 :
277 0 : k = write(STDOUT_FILENO, f->out_buffer, f->out_buffer_full);
278 0 : if (k < 0) {
279 :
280 0 : if (errno == EAGAIN)
281 0 : f->stdout_writable = false;
282 0 : else if (IN_SET(errno, EIO, EPIPE, ECONNRESET)) {
283 0 : f->stdout_writable = false;
284 0 : f->stdout_hangup = true;
285 0 : f->stdout_event_source = sd_event_source_unref(f->stdout_event_source);
286 : } else {
287 0 : log_error_errno(errno, "write(): %m");
288 0 : return pty_forward_done(f, -errno);
289 : }
290 :
291 : } else {
292 :
293 0 : if (k > 0) {
294 0 : f->last_char = f->out_buffer[k-1];
295 0 : f->last_char_set = true;
296 : }
297 :
298 0 : assert(f->out_buffer_full >= (size_t) k);
299 0 : memmove(f->out_buffer, f->out_buffer + k, f->out_buffer_full - k);
300 0 : f->out_buffer_full -= k;
301 : }
302 : }
303 : }
304 :
305 0 : if (f->stdin_hangup || f->stdout_hangup || f->master_hangup) {
306 : /* Exit the loop if any side hung up and if there's
307 : * nothing more to write or nothing we could write. */
308 :
309 0 : if ((f->out_buffer_full <= 0 || f->stdout_hangup) &&
310 0 : (f->in_buffer_full <= 0 || f->master_hangup))
311 0 : return pty_forward_done(f, 0);
312 : }
313 :
314 : /* If we were asked to drain, and there's nothing more to handle from the master, then call the callback
315 : * too. */
316 0 : if (f->drain && drained(f))
317 0 : return pty_forward_done(f, 0);
318 :
319 0 : return 0;
320 : }
321 :
322 0 : static int on_master_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
323 0 : PTYForward *f = userdata;
324 :
325 0 : assert(f);
326 0 : assert(e);
327 0 : assert(e == f->master_event_source);
328 0 : assert(fd >= 0);
329 0 : assert(fd == f->master);
330 :
331 0 : if (revents & (EPOLLIN|EPOLLHUP))
332 0 : f->master_readable = true;
333 :
334 0 : if (revents & (EPOLLOUT|EPOLLHUP))
335 0 : f->master_writable = true;
336 :
337 0 : return shovel(f);
338 : }
339 :
340 0 : static int on_stdin_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
341 0 : PTYForward *f = userdata;
342 :
343 0 : assert(f);
344 0 : assert(e);
345 0 : assert(e == f->stdin_event_source);
346 0 : assert(fd >= 0);
347 0 : assert(fd == STDIN_FILENO);
348 :
349 0 : if (revents & (EPOLLIN|EPOLLHUP))
350 0 : f->stdin_readable = true;
351 :
352 0 : return shovel(f);
353 : }
354 :
355 0 : static int on_stdout_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
356 0 : PTYForward *f = userdata;
357 :
358 0 : assert(f);
359 0 : assert(e);
360 0 : assert(e == f->stdout_event_source);
361 0 : assert(fd >= 0);
362 0 : assert(fd == STDOUT_FILENO);
363 :
364 0 : if (revents & (EPOLLOUT|EPOLLHUP))
365 0 : f->stdout_writable = true;
366 :
367 0 : return shovel(f);
368 : }
369 :
370 0 : static int on_sigwinch_event(sd_event_source *e, const struct signalfd_siginfo *si, void *userdata) {
371 0 : PTYForward *f = userdata;
372 : struct winsize ws;
373 :
374 0 : assert(f);
375 0 : assert(e);
376 0 : assert(e == f->sigwinch_event_source);
377 :
378 : /* The window size changed, let's forward that. */
379 0 : if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
380 0 : (void) ioctl(f->master, TIOCSWINSZ, &ws);
381 :
382 0 : return 0;
383 : }
384 :
385 0 : int pty_forward_new(
386 : sd_event *event,
387 : int master,
388 : PTYForwardFlags flags,
389 : PTYForward **ret) {
390 :
391 0 : _cleanup_(pty_forward_freep) PTYForward *f = NULL;
392 : struct winsize ws;
393 : int r;
394 :
395 0 : f = new(PTYForward, 1);
396 0 : if (!f)
397 0 : return -ENOMEM;
398 :
399 0 : *f = (struct PTYForward) {
400 : .flags = flags,
401 : .master = -1,
402 : };
403 :
404 0 : if (event)
405 0 : f->event = sd_event_ref(event);
406 : else {
407 0 : r = sd_event_default(&f->event);
408 0 : if (r < 0)
409 0 : return r;
410 : }
411 :
412 0 : if (!(flags & PTY_FORWARD_READ_ONLY)) {
413 0 : r = fd_nonblock(STDIN_FILENO, true);
414 0 : if (r < 0)
415 0 : return r;
416 :
417 0 : r = fd_nonblock(STDOUT_FILENO, true);
418 0 : if (r < 0)
419 0 : return r;
420 : }
421 :
422 0 : r = fd_nonblock(master, true);
423 0 : if (r < 0)
424 0 : return r;
425 :
426 0 : f->master = master;
427 :
428 0 : if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0) {
429 : /* If we can't get the resolution from the output fd, then use our internal, regular width/height,
430 : * i.e. something derived from $COLUMNS and $LINES if set. */
431 :
432 0 : ws = (struct winsize) {
433 0 : .ws_row = lines(),
434 0 : .ws_col = columns(),
435 : };
436 : }
437 :
438 0 : (void) ioctl(master, TIOCSWINSZ, &ws);
439 :
440 0 : if (!(flags & PTY_FORWARD_READ_ONLY)) {
441 0 : if (tcgetattr(STDIN_FILENO, &f->saved_stdin_attr) >= 0) {
442 : struct termios raw_stdin_attr;
443 :
444 0 : f->saved_stdin = true;
445 :
446 0 : raw_stdin_attr = f->saved_stdin_attr;
447 0 : cfmakeraw(&raw_stdin_attr);
448 0 : raw_stdin_attr.c_oflag = f->saved_stdin_attr.c_oflag;
449 0 : tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin_attr);
450 : }
451 :
452 0 : if (tcgetattr(STDOUT_FILENO, &f->saved_stdout_attr) >= 0) {
453 : struct termios raw_stdout_attr;
454 :
455 0 : f->saved_stdout = true;
456 :
457 0 : raw_stdout_attr = f->saved_stdout_attr;
458 0 : cfmakeraw(&raw_stdout_attr);
459 0 : raw_stdout_attr.c_iflag = f->saved_stdout_attr.c_iflag;
460 0 : raw_stdout_attr.c_lflag = f->saved_stdout_attr.c_lflag;
461 0 : tcsetattr(STDOUT_FILENO, TCSANOW, &raw_stdout_attr);
462 : }
463 :
464 0 : r = sd_event_add_io(f->event, &f->stdin_event_source, STDIN_FILENO, EPOLLIN|EPOLLET, on_stdin_event, f);
465 0 : if (r < 0 && r != -EPERM)
466 0 : return r;
467 :
468 0 : if (r >= 0)
469 0 : (void) sd_event_source_set_description(f->stdin_event_source, "ptyfwd-stdin");
470 : }
471 :
472 0 : r = sd_event_add_io(f->event, &f->stdout_event_source, STDOUT_FILENO, EPOLLOUT|EPOLLET, on_stdout_event, f);
473 0 : if (r == -EPERM)
474 : /* stdout without epoll support. Likely redirected to regular file. */
475 0 : f->stdout_writable = true;
476 0 : else if (r < 0)
477 0 : return r;
478 : else
479 0 : (void) sd_event_source_set_description(f->stdout_event_source, "ptyfwd-stdout");
480 :
481 0 : r = sd_event_add_io(f->event, &f->master_event_source, master, EPOLLIN|EPOLLOUT|EPOLLET, on_master_event, f);
482 0 : if (r < 0)
483 0 : return r;
484 :
485 0 : (void) sd_event_source_set_description(f->master_event_source, "ptyfwd-master");
486 :
487 0 : r = sd_event_add_signal(f->event, &f->sigwinch_event_source, SIGWINCH, on_sigwinch_event, f);
488 0 : if (r < 0)
489 0 : return r;
490 :
491 0 : (void) sd_event_source_set_description(f->sigwinch_event_source, "ptyfwd-sigwinch");
492 :
493 0 : *ret = TAKE_PTR(f);
494 :
495 0 : return 0;
496 : }
497 :
498 0 : PTYForward *pty_forward_free(PTYForward *f) {
499 0 : pty_forward_disconnect(f);
500 0 : return mfree(f);
501 : }
502 :
503 0 : int pty_forward_get_last_char(PTYForward *f, char *ch) {
504 0 : assert(f);
505 0 : assert(ch);
506 :
507 0 : if (!f->last_char_set)
508 0 : return -ENXIO;
509 :
510 0 : *ch = f->last_char;
511 0 : return 0;
512 : }
513 :
514 0 : int pty_forward_set_ignore_vhangup(PTYForward *f, bool b) {
515 : int r;
516 :
517 0 : assert(f);
518 :
519 0 : if (!!(f->flags & PTY_FORWARD_IGNORE_VHANGUP) == b)
520 0 : return 0;
521 :
522 0 : SET_FLAG(f->flags, PTY_FORWARD_IGNORE_VHANGUP, b);
523 :
524 0 : if (!ignore_vhangup(f)) {
525 :
526 : /* We shall now react to vhangup()s? Let's check
527 : * immediately if we might be in one */
528 :
529 0 : f->master_readable = true;
530 0 : r = shovel(f);
531 0 : if (r < 0)
532 0 : return r;
533 : }
534 :
535 0 : return 0;
536 : }
537 :
538 0 : bool pty_forward_get_ignore_vhangup(PTYForward *f) {
539 0 : assert(f);
540 :
541 0 : return !!(f->flags & PTY_FORWARD_IGNORE_VHANGUP);
542 : }
543 :
544 0 : bool pty_forward_is_done(PTYForward *f) {
545 0 : assert(f);
546 :
547 0 : return f->done;
548 : }
549 :
550 0 : void pty_forward_set_handler(PTYForward *f, PTYForwardHandler cb, void *userdata) {
551 0 : assert(f);
552 :
553 0 : f->handler = cb;
554 0 : f->userdata = userdata;
555 0 : }
556 :
557 0 : bool pty_forward_drain(PTYForward *f) {
558 0 : assert(f);
559 :
560 : /* Starts draining the forwarder. Specifically:
561 : *
562 : * - Returns true if there are no unprocessed bytes from the pty, false otherwise
563 : *
564 : * - Makes sure the handler function is called the next time the number of unprocessed bytes hits zero
565 : */
566 :
567 0 : f->drain = true;
568 0 : return drained(f);
569 : }
570 :
571 0 : int pty_forward_set_priority(PTYForward *f, int64_t priority) {
572 : int r;
573 0 : assert(f);
574 :
575 0 : r = sd_event_source_set_priority(f->stdin_event_source, priority);
576 0 : if (r < 0)
577 0 : return r;
578 :
579 0 : r = sd_event_source_set_priority(f->stdout_event_source, priority);
580 0 : if (r < 0)
581 0 : return r;
582 :
583 0 : r = sd_event_source_set_priority(f->master_event_source, priority);
584 0 : if (r < 0)
585 0 : return r;
586 :
587 0 : r = sd_event_source_set_priority(f->sigwinch_event_source, priority);
588 0 : if (r < 0)
589 0 : return r;
590 :
591 0 : return 0;
592 : }
593 :
594 0 : int pty_forward_set_width_height(PTYForward *f, unsigned width, unsigned height) {
595 : struct winsize ws;
596 :
597 0 : assert(f);
598 :
599 0 : if (width == (unsigned) -1 && height == (unsigned) -1)
600 0 : return 0; /* noop */
601 :
602 0 : if (width != (unsigned) -1 &&
603 0 : (width == 0 || width > USHRT_MAX))
604 0 : return -ERANGE;
605 :
606 0 : if (height != (unsigned) -1 &&
607 0 : (height == 0 || height > USHRT_MAX))
608 0 : return -ERANGE;
609 :
610 0 : if (width == (unsigned) -1 || height == (unsigned) -1) {
611 0 : if (ioctl(f->master, TIOCGWINSZ, &ws) < 0)
612 0 : return -errno;
613 :
614 0 : if (width != (unsigned) -1)
615 0 : ws.ws_col = width;
616 0 : if (height != (unsigned) -1)
617 0 : ws.ws_row = height;
618 : } else
619 0 : ws = (struct winsize) {
620 : .ws_row = height,
621 : .ws_col = width,
622 : };
623 :
624 0 : if (ioctl(f->master, TIOCSWINSZ, &ws) < 0)
625 0 : return -errno;
626 :
627 : /* Make sure we ignore SIGWINCH window size events from now on */
628 0 : f->sigwinch_event_source = sd_event_source_unref(f->sigwinch_event_source);
629 :
630 0 : return 0;
631 : }
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