1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 /*
18  * Handles the data in ~/.telescope
19  *
20  * TODO: add some form of locking on the files
21  */
22 
23 #include "compat.h"
24 
25 #include <sys/stat.h>
26 #include <sys/types.h>
27 
28 #include <dirent.h>
29 #include <errno.h>
30 #include <fcntl.h>
31 #include <limits.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 
37 #include "pages.h"
38 #include "telescope.h"
39 
40 static void		 die(void) __attribute__((__noreturn__));
41 static void		 send_file(uint32_t, FILE *);
42 static void		 handle_get(struct imsg*, size_t);
43 static int		 select_non_dot(const struct dirent *);
44 static int		 select_non_dotdot(const struct dirent *);
45 static void		 handle_get_file(struct imsg*, size_t);
46 static void		 handle_quit(struct imsg*, size_t);
47 static void		 handle_bookmark_page(struct imsg*, size_t);
48 static void		 handle_save_cert(struct imsg*, size_t);
49 static void		 handle_update_cert(struct imsg*, size_t);
50 static void		 handle_file_open(struct imsg*, size_t);
51 static void		 handle_session_start(struct imsg*, size_t);
52 static void		 handle_session_tab(struct imsg*, size_t);
53 static void		 handle_session_tab_title(struct imsg*, size_t);
54 static void		 handle_session_end(struct imsg*, size_t);
55 static void		 handle_dispatch_imsg(int, short, void*);
56 static int		 fs_send_ui(int, uint32_t, int, const void *, uint16_t);
57 
58 static struct imsgev		*iev_ui;
59 static FILE			*session;
60 
61 static char	base_path[PATH_MAX];
62 static char	lockfile_path[PATH_MAX];
63 static char	bookmark_file[PATH_MAX];
64 static char	known_hosts_file[PATH_MAX], known_hosts_tmp[PATH_MAX];
65 static char	crashed_file[PATH_MAX];
66 
67 char	session_file[PATH_MAX];
68 
69 static imsg_handlerfn *handlers[] = {
70 	[IMSG_GET] = handle_get,
71 	[IMSG_GET_FILE] = handle_get_file,
72 	[IMSG_QUIT] = handle_quit,
73 	[IMSG_BOOKMARK_PAGE] = handle_bookmark_page,
74 	[IMSG_SAVE_CERT] = handle_save_cert,
75 	[IMSG_UPDATE_CERT] = handle_update_cert,
76 	[IMSG_FILE_OPEN] = handle_file_open,
77 	[IMSG_SESSION_START] = handle_session_start,
78 	[IMSG_SESSION_TAB] = handle_session_tab,
79 	[IMSG_SESSION_TAB_TITLE] = handle_session_tab_title,
80 	[IMSG_SESSION_END] = handle_session_end,
81 };
82 
83 static void __attribute__((__noreturn__))
84 die(void)
85 {
86 	abort(); 		/* TODO */
87 }
88 
89 static void
90 send_file(uint32_t peerid, FILE *f)
91 {
92 	ssize_t	 r;
93 	char	 buf[BUFSIZ];
94 
95 	for (;;) {
96 		r = fread(buf, 1, sizeof(buf), f);
97 		if (r != 0)
98 			fs_send_ui(IMSG_BUF, peerid, -1, buf, r);
99 		if (r != sizeof(buf))
100 			break;
101 	}
102 	fs_send_ui(IMSG_EOF, peerid, -1, NULL, 0);
103 	fclose(f);
104 }
105 
106 static void
107 handle_get(struct imsg *imsg, size_t datalen)
108 {
109 	const char	*bpath = "bookmarks.gmi";
110 	char		 path[PATH_MAX];
111 	FILE		*f;
112 	const char	*data, *p;
113 	size_t		 i;
114 	struct page {
115 		const char	*name;
116 		const char	*path;
117 		const uint8_t	*data;
118 		size_t		 len;
119 	} pages[] = {
120 		{"about",	NULL,	about_about,	about_about_len},
121 		{"blank",	NULL,	about_blank,	about_blank_len},
122 		{"bookmarks",	bpath,	bookmarks,	bookmarks_len},
123 		{"crash",	NULL,	about_crash,	about_crash_len},
124 		{"help",	NULL,	about_help,	about_help_len},
125 		{"license",	NULL,	about_license,	about_license_len},
126 		{"new",		NULL,	about_new,	about_new_len},
127 	}, *page = NULL;
128 
129 	data = imsg->data;
130 	if (data[datalen-1] != '\0') /* make sure it's NUL-terminated */
131 		die();
132 	if ((data = strchr(data, ':')) == NULL)
133 		goto notfound;
134 	data++;
135 
136 	for (i = 0; i < sizeof(pages)/sizeof(pages[0]); ++i)
137 		if (!strcmp(data, pages[i].name)) {
138 			page = &pages[i];
139 			break;
140 		}
141 
142 	if (page == NULL)
143 		goto notfound;
144 
145 	strlcpy(path, base_path, sizeof(path));
146 	strlcat(path, "/", sizeof(path));
147 	if (page->path != NULL)
148 		strlcat(path, page->path, sizeof(path));
149 	else {
150 		strlcat(path, "pages/about_", sizeof(path));
151 		strlcat(path, page->name, sizeof(path));
152 		strlcat(path, ".gmi", sizeof(path));
153 	}
154 
155 	if ((f = fopen(path, "r")) == NULL) {
156 		fs_send_ui(IMSG_BUF, imsg->hdr.peerid, -1,
157 		    page->data, page->len);
158 		fs_send_ui(IMSG_EOF, imsg->hdr.peerid, -1,
159 		    NULL, 0);
160 		return;
161 	}
162 
163 	send_file(imsg->hdr.peerid, f);
164 	return;
165 
166 notfound:
167 	p = "# not found!\n";
168 	fs_send_ui(IMSG_BUF, imsg->hdr.peerid, -1, p, strlen(p));
169 	fs_send_ui(IMSG_EOF, imsg->hdr.peerid, -1, NULL, 0);
170 }
171 
172 static inline void
173 send_hdr(uint32_t peerid, int code, const char *meta)
174 {
175 	fs_send_ui(IMSG_GOT_CODE, peerid, -1, &code, sizeof(code));
176 	fs_send_ui(IMSG_GOT_META, peerid, -1, meta, strlen(meta)+1);
177 }
178 
179 static inline void
180 send_errno(uint32_t peerid, int code, const char *str, int no)
181 {
182 	char *s;
183 
184 	if (asprintf(&s, "%s: %s", str, strerror(no)) == -1)
185 		s = NULL;
186 
187 	send_hdr(peerid, code, s == NULL ? str : s);
188 	free(s);
189 }
190 
191 static inline const char *
192 file_type(const char *path)
193 {
194 	struct mapping {
195 		const char	*ext;
196 		const char	*mime;
197 	} ms[] = {
198 		{"diff",	"text/x-patch"},
199 		{"gemini",	"text/gemini"},
200 		{"gmi",		"text/gemini"},
201 		{"markdown",	"text/plain"},
202 		{"md",		"text/plain"},
203 		{"patch",	"text/x-patch"},
204 		{"txt",		"text/plain"},
205 		{NULL, NULL},
206 	}, *m;
207 	char *dot;
208 
209 	if ((dot = strrchr(path, '.')) == NULL)
210 		return NULL;
211 
212 	dot++;
213 
214 	for (m = ms; m->ext != NULL; ++m)
215 		if (!strcmp(m->ext, dot))
216 			return m->mime;
217 
218 	return NULL;
219 }
220 
221 static int
222 select_non_dot(const struct dirent *d)
223 {
224 	return strcmp(d->d_name, ".");
225 }
226 
227 static int
228 select_non_dotdot(const struct dirent *d)
229 {
230 	return strcmp(d->d_name, ".") && strcmp(d->d_name, "..");
231 }
232 
233 static inline void
234 send_dir(uint32_t peerid, const char *path)
235 {
236 	struct dirent	**names;
237 	struct evbuffer	 *ev;
238 	char		 *s;
239 	int		(*selector)(const struct dirent *) = select_non_dot;
240 	int		  i, len, no;
241 
242 	if (!has_suffix(path, "/")) {
243 		if (asprintf(&s, "%s/", path) == -1)
244 			die();
245 		send_hdr(peerid, 30, s);
246 		free(s);
247 		return;
248 	}
249 
250 	if (!strcmp(path, "/"))
251 		selector = select_non_dotdot;
252 
253 	if ((ev = evbuffer_new()) == NULL ||
254 	    (len = scandir(path, &names, selector, alphasort)) == -1) {
255 		no = errno;
256 		evbuffer_free(ev);
257 		send_errno(peerid, 40, "failure reading the directory", no);
258 		return;
259 	}
260 
261 	evbuffer_add_printf(ev, "# Index of %s\n\n", path);
262 	for (i = 0; i < len; ++i) {
263 		evbuffer_add_printf(ev, "=> %s", names[i]->d_name);
264 		if (names[i]->d_type == DT_DIR)
265 			evbuffer_add(ev, "/", 1);
266 		evbuffer_add(ev, "\n", 1);
267 	}
268 
269 	send_hdr(peerid, 20, "text/gemini");
270 	fs_send_ui(IMSG_BUF, peerid, -1,
271 	    EVBUFFER_DATA(ev), EVBUFFER_LENGTH(ev));
272 	fs_send_ui(IMSG_EOF, peerid, -1, NULL, 0);
273 
274 	evbuffer_free(ev);
275 	free(names);
276 }
277 
278 static void
279 handle_get_file(struct imsg *imsg, size_t datalen)
280 {
281 	struct stat	 sb;
282 	FILE		*f;
283 	char		*data;
284 	const char	*meta = NULL;
285 
286 	data = imsg->data;
287 	data[datalen-1] = '\0';
288 
289 	if ((f = fopen(data, "r")) == NULL) {
290 		send_errno(imsg->hdr.peerid, 51, "can't open", errno);
291 		return;
292 	}
293 
294 	if (fstat(fileno(f), &sb) == -1) {
295 		send_errno(imsg->hdr.peerid, 40, "fstat", errno);
296 		return;
297 	}
298 
299 	if (S_ISDIR(sb.st_mode)) {
300 		fclose(f);
301 		send_dir(imsg->hdr.peerid, data);
302 		return;
303 	}
304 
305 	if ((meta = file_type(data)) == NULL) {
306 		fclose(f);
307 		send_hdr(imsg->hdr.peerid, 51,
308 		    "don't know how to visualize this file");
309 		return;
310 	}
311 
312 	send_hdr(imsg->hdr.peerid, 20, meta);
313 	send_file(imsg->hdr.peerid, f);
314 }
315 
316 static void
317 handle_quit(struct imsg *imsg, size_t datalen)
318 {
319 	if (!safe_mode)
320 		unlink(crashed_file);
321 
322 	event_loopbreak();
323 }
324 
325 static void
326 handle_bookmark_page(struct imsg *imsg, size_t datalen)
327 {
328 	char	*data;
329 	int	 res;
330 	FILE	*f;
331 
332 	data = imsg->data;
333 	if (data[datalen-1] != '\0')
334 		die();
335 
336 	if ((f = fopen(bookmark_file, "a")) == NULL) {
337 		res = errno;
338 		goto end;
339 	}
340 	fprintf(f, "=> %s\n", data);
341 	fclose(f);
342 
343 	res = 0;
344 end:
345 	fs_send_ui(IMSG_BOOKMARK_OK, 0, -1, &res, sizeof(res));
346 }
347 
348 static void
349 handle_save_cert(struct imsg *imsg, size_t datalen)
350 {
351 	struct tofu_entry	 e;
352 	FILE			*f;
353 	int			 res;
354 
355 	/* TODO: traverse the file to avoid duplications? */
356 
357 	if (datalen != sizeof(e))
358 		die();
359 	memcpy(&e, imsg->data, datalen);
360 
361 	if ((f = fopen(known_hosts_file, "a")) == NULL) {
362 		res = errno;
363 		goto end;
364 	}
365 	fprintf(f, "%s %s %d\n", e.domain, e.hash, e.verified);
366 	fclose(f);
367 
368 	res = 0;
369 end:
370 	fs_send_ui(IMSG_SAVE_CERT_OK, imsg->hdr.peerid, -1,
371 	    &res, sizeof(res));
372 }
373 
374 static void
375 handle_update_cert(struct imsg *imsg, size_t datalen)
376 {
377 	FILE	*tmp, *f;
378 	struct	 tofu_entry entry;
379 	char	 sfn[PATH_MAX], *line = NULL, *t;
380 	size_t	 l, linesize = 0;
381 	ssize_t	 linelen;
382 	int	 fd, e, res = 0;
383 
384 	if (datalen != sizeof(entry))
385 		die();
386 	memcpy(&entry, imsg->data, datalen);
387 
388 	strlcpy(sfn, known_hosts_tmp, sizeof(sfn));
389 	if ((fd = mkstemp(sfn)) == -1 ||
390 	    (tmp = fdopen(fd, "w")) == NULL) {
391 		if (fd != -1) {
392 			unlink(sfn);
393 			close(fd);
394 		}
395 		res = 0;
396 		goto end;
397 	}
398 
399 	if ((f = fopen(known_hosts_file, "r")) == NULL) {
400 		unlink(sfn);
401 		fclose(tmp);
402                 res = 0;
403 		goto end;
404 	}
405 
406 	l = strlen(entry.domain);
407 	while ((linelen = getline(&line, &linesize, f)) != -1) {
408 		if ((t = strstr(line, entry.domain)) != NULL &&
409 		    (line[l] == ' ' || line[l] == '\t'))
410 			continue;
411 		/* line has a trailing \n */
412 		fprintf(tmp, "%s", line);
413 	}
414 	fprintf(tmp, "%s %s %d\n", entry.domain, entry.hash, entry.verified);
415 
416 	free(line);
417 	e = ferror(tmp);
418 
419 	fclose(tmp);
420 	fclose(f);
421 
422 	if (e) {
423 		unlink(sfn);
424 		res = 0;
425 		goto end;
426 	}
427 
428 	res = rename(sfn, known_hosts_file) != -1;
429 
430 end:
431 	fs_send_ui(IMSG_UPDATE_CERT_OK, imsg->hdr.peerid, -1,
432 	    &res, sizeof(res));
433 }
434 
435 static void
436 handle_file_open(struct imsg *imsg, size_t datalen)
437 {
438 	char	*path, *e;
439 	int	 fd;
440 
441 	path = imsg->data;
442 	if (path[datalen-1] != '\0')
443 		die();
444 
445 	if ((fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0644)) == -1) {
446 		e = strerror(errno);
447 		fs_send_ui(IMSG_FILE_OPENED, imsg->hdr.peerid, -1,
448 		    e, strlen(e)+1);
449 	} else
450 		fs_send_ui(IMSG_FILE_OPENED, imsg->hdr.peerid, fd,
451 		    NULL, 0);
452 }
453 
454 static void
455 handle_session_start(struct imsg *imsg, size_t datalen)
456 {
457 	if (datalen != 0)
458 		die();
459 
460 	if ((session = fopen(session_file, "w")) == NULL)
461 		die();
462 }
463 
464 static void
465 handle_session_tab(struct imsg *imsg, size_t datalen)
466 {
467 	char		*url;
468 	uint32_t	 flags;
469 
470 	if (session == NULL)
471 		die();
472 
473 	flags = imsg->hdr.peerid;
474 	url = imsg->data;
475 	if (datalen == 0 || url[datalen-1] != '\0')
476 		die();
477 	fprintf(session, "%s", url);
478 
479 	if (flags & TAB_CURRENT)
480 		fprintf(session, " current ");
481 	else
482 		fprintf(session, " - ");
483 }
484 
485 static void
486 handle_session_tab_title(struct imsg *imsg, size_t datalen)
487 {
488 	const char	*title;
489 
490 	title = imsg->data;
491 	if (title == NULL) {
492 		datalen = 1;
493 		title = "";
494 	}
495 
496 	if (title[datalen-1] != '\0')
497 		die();
498 
499 	fprintf(session, "%s\n", title);
500 }
501 
502 static void
503 handle_session_end(struct imsg *imsg, size_t datalen)
504 {
505 	if (session == NULL)
506 		die();
507 	fclose(session);
508 	session = NULL;
509 }
510 
511 static void
512 handle_dispatch_imsg(int fd, short ev, void *d)
513 {
514 	struct imsgev	*iev = d;
515 	int		 e;
516 
517 	if (dispatch_imsg(iev, ev, handlers, sizeof(handlers)) == -1) {
518 		/*
519 		 * This should leave a ~/.telescope/crashed file to
520 		 * trigger about:crash on next run.  Unfortunately, if
521 		 * the main process dies the fs sticks around and
522 		 * doesn't notice that the fd was closed.  Why EV_READ
523 		 * is not triggered when a fd is closed on the other end?
524 		 */
525 		e = errno;
526 		if ((fd = open(crashed_file, O_CREAT|O_TRUNC|O_WRONLY, 0600))
527 		    == -1)
528 			err(1, "open");
529 		close(fd);
530 		errx(1, "connection closed: %s", strerror(e));
531 	}
532 }
533 
534 static int
535 fs_send_ui(int type, uint32_t peerid, int fd, const void *data,
536     uint16_t datalen)
537 {
538 	return imsg_compose_event(iev_ui, type, peerid, 0, fd,
539 	    data, datalen);
540 }
541 
542 int
543 fs_init(void)
544 {
545 	strlcpy(base_path, getenv("HOME"), sizeof(base_path));
546 	strlcat(base_path, "/.telescope", sizeof(base_path));
547 	mkdir(base_path, 0700);
548 
549 	strlcpy(lockfile_path, base_path, sizeof(lockfile_path));
550 	strlcat(lockfile_path, "/lock", sizeof(lockfile_path));
551 
552 	strlcpy(bookmark_file, base_path, sizeof(bookmark_file));
553 	strlcat(bookmark_file, "/bookmarks.gmi", sizeof(bookmark_file));
554 
555 	strlcpy(known_hosts_file, base_path, sizeof(known_hosts_file));
556 	strlcat(known_hosts_file, "/known_hosts", sizeof(known_hosts_file));
557 
558 	strlcpy(known_hosts_tmp, base_path, sizeof(known_hosts_tmp));
559 	strlcat(known_hosts_tmp, "/known_hosts.tmp.XXXXXXXXXX",
560 	    sizeof(known_hosts_file));
561 
562 	strlcpy(session_file, base_path, sizeof(session_file));
563 	strlcat(session_file, "/session", sizeof(session_file));
564 
565 	strlcpy(crashed_file, base_path, sizeof(crashed_file));
566 	strlcat(crashed_file, "/crashed", sizeof(crashed_file));
567 
568 	return 1;
569 }
570 
571 int
572 fs_main(void)
573 {
574 	setproctitle("fs");
575 
576 	fs_init();
577 
578 	event_init();
579 
580 	/* Setup pipe and event handler to the main process */
581 	if ((iev_ui = malloc(sizeof(*iev_ui))) == NULL)
582 		die();
583 	imsg_init(&iev_ui->ibuf, 3);
584 	iev_ui->handler = handle_dispatch_imsg;
585 	iev_ui->events = EV_READ;
586 	event_set(&iev_ui->ev, iev_ui->ibuf.fd, iev_ui->events,
587 	    iev_ui->handler, iev_ui);
588 	event_add(&iev_ui->ev, NULL);
589 
590 	sandbox_fs_process();
591 
592 	event_dispatch();
593 	return 0;
594 }
595 
596 
597 
598 /*
599  * Check if the last time telescope crashed.  The check is done by
600  * looking at `crashed_file': if it exists then last time we crashed.
601  * Then, while here, touch the file too.  During IMSG_QUIT we'll
602  * remove it.
603  */
604 int
605 last_time_crashed(void)
606 {
607 	int fd, crashed = 1;
608 
609 	if (safe_mode)
610 		return 0;
611 
612 	if (unlink(crashed_file) == -1 && errno == ENOENT)
613 		crashed = 0;
614 
615 	if ((fd = open(crashed_file, O_CREAT|O_WRONLY, 0600)) == -1)
616 		return crashed;
617 	close(fd);
618 
619 	return crashed;
620 }
621 
622 int
623 lock_session(void)
624 {
625 	struct flock	lock;
626 	int		fd;
627 
628 	if ((fd = open(lockfile_path, O_WRONLY|O_CREAT, 0600)) == -1)
629 		return -1;
630 
631 	lock.l_start = 0;
632 	lock.l_len = 0;
633 	lock.l_type = F_WRLCK;
634 	lock.l_whence = SEEK_SET;
635 
636 	if (fcntl(fd, F_SETLK, &lock) == -1) {
637 		close(fd);
638 		return -1;
639 	}
640 
641 	return fd;
642 }
643 
644 static int
645 parse_khost_line(char *line, char *tmp[3])
646 {
647 	char **ap;
648 
649 	for (ap = tmp; ap < &tmp[3] &&
650 	    (*ap = strsep(&line, " \t\n")) != NULL;) {
651 		if (**ap != '\0')
652 			ap++;
653 	}
654 
655 	return ap == &tmp[3] && *line == '\0';
656 }
657 
658 int
659 load_certs(struct ohash *h)
660 {
661 	char		*tmp[3], *line = NULL;
662 	const char	*errstr;
663 	size_t		 lineno = 0, linesize = 0;
664 	ssize_t		 linelen;
665 	FILE		*f;
666 	struct tofu_entry *e;
667 
668 	if ((f = fopen(known_hosts_file, "r")) == NULL)
669 		return 0;
670 
671 	while ((linelen = getline(&line, &linesize, f)) != -1) {
672 		if ((e = calloc(1, sizeof(*e))) == NULL)
673 			abort();
674 
675 		lineno++;
676 
677 		if (parse_khost_line(line, tmp)) {
678 			strlcpy(e->domain, tmp[0], sizeof(e->domain));
679 			strlcpy(e->hash, tmp[1], sizeof(e->hash));
680 
681 			e->verified = strtonum(tmp[2], 0, 1, &errstr);
682 			if (errstr != NULL)
683 				errx(1, "%s:%zu verification for %s is %s: %s",
684 				    known_hosts_file, lineno,
685 				    e->domain, errstr, tmp[2]);
686 			tofu_add(h, e);
687 		} else {
688 			warnx("%s:%zu invalid entry",
689 			    known_hosts_file, lineno);
690 			free(e);
691 		}
692 	}
693 
694 	free(line);
695 	return ferror(f);
696 }
697