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 #include "gmid.h"
18 
19 #include <sys/stat.h>
20 
21 #include <assert.h>
22 #include <errno.h>
23 #include <event.h>
24 #include <fcntl.h>
25 #include <fnmatch.h>
26 #include <limits.h>
27 #include <string.h>
28 
29 static struct client	 clients[MAX_USERS];
30 static struct tls	*ctx;
31 
32 static struct event e4, e6, imsgev, siginfo, sigusr2;
33 static int has_ipv6, has_siginfo;
34 
35 int connected_clients;
36 
37 static inline int matches(const char*, const char*);
38 
39 static inline void yield_read(int, struct client*, statefn);
40 static inline void yield_write(int, struct client*, statefn);
41 
42 static int	 check_path(struct client*, const char*, int*);
43 static void	 open_file(struct client*);
44 static void	 check_for_cgi(struct client*);
45 static void	 handle_handshake(int, short, void*);
46 static char	*strip_path(char*, int);
47 static void	 fmt_sbuf(const char*, struct client*, const char*);
48 static int	 apply_block_return(struct client*);
49 static int	 apply_require_ca(struct client*);
50 static void	 handle_open_conn(int, short, void*);
51 static void	 start_reply(struct client*, int, const char*);
52 static void	 handle_start_reply(int, short, void*);
53 static size_t	 host_nth(struct vhost*);
54 static void	 start_cgi(const char*, const char*, struct client*);
55 static void	 open_dir(struct client*);
56 static void	 redirect_canonical_dir(struct client*);
57 static void	 enter_handle_dirlist(int, short, void*);
58 static void	 handle_dirlist(int, short, void*);
59 static int 	 read_next_dir_entry(struct client*);
60 static void	 send_directory_listing(int, short, void*);
61 static void	 handle_cgi_reply(int, short, void*);
62 static void	 handle_copy(int, short, void*);
63 static void	 close_conn(int, short, void*);
64 static void	 do_accept(int, short, void*);
65 struct client	*client_by_id(int);
66 static void	 handle_imsg_cgi_res(struct imsgbuf*, struct imsg*, size_t);
67 static void	 handle_imsg_quit(struct imsgbuf*, struct imsg*, size_t);
68 static void	 handle_siginfo(int, short, void*);
69 
70 static imsg_handlerfn *handlers[] = {
71 	[IMSG_QUIT] = handle_imsg_quit,
72 	[IMSG_CGI_RES] = handle_imsg_cgi_res,
73 };
74 
75 static inline int
76 matches(const char *pattern, const char *path)
77 {
78 	if (*path == '/')
79 		path++;
80 	return !fnmatch(pattern, path, 0);
81 }
82 
83 static inline void
84 yield_read(int fd, struct client *c, statefn fn)
85 {
86 	event_once(fd, EV_READ, fn, c, NULL);
87 }
88 
89 static inline void
90 yield_write(int fd, struct client *c, statefn fn)
91 {
92 	event_once(fd, EV_WRITE, fn, c, NULL);
93 }
94 
95 const char *
96 vhost_lang(struct vhost *v, const char *path)
97 {
98 	struct location *loc;
99 
100 	if (v == NULL || path == NULL)
101 		return NULL;
102 
103 	loc = TAILQ_FIRST(&v->locations);
104 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
105 		if (loc->lang != NULL) {
106 			if (matches(loc->match, path))
107 				return loc->lang;
108 		}
109 	}
110 
111 	return TAILQ_FIRST(&v->locations)->lang;
112 }
113 
114 const char *
115 vhost_default_mime(struct vhost *v, const char *path)
116 {
117 	struct location *loc;
118 	const char *default_mime = "application/octet-stream";
119 
120 	if (v == NULL || path == NULL)
121 		return default_mime;
122 
123 	loc = TAILQ_FIRST(&v->locations);
124 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
125 		if (loc->default_mime != NULL) {
126 			if (matches(loc->match, path))
127 				return loc->default_mime;
128 		}
129 	}
130 
131 	loc = TAILQ_FIRST(&v->locations);
132 	if (loc->default_mime != NULL)
133 		return loc->default_mime;
134 	return default_mime;
135 }
136 
137 const char *
138 vhost_index(struct vhost *v, const char *path)
139 {
140 	struct location *loc;
141 	const char *index = "index.gmi";
142 
143 	if (v == NULL || path == NULL)
144 		return index;
145 
146 	loc = TAILQ_FIRST(&v->locations);
147 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
148 		if (loc->index != NULL) {
149 			if (matches(loc->match, path))
150 				return loc->index;
151 		}
152 	}
153 
154 	loc = TAILQ_FIRST(&v->locations);
155 	if (loc->index != NULL)
156 		return loc->index;
157 	return index;
158 }
159 
160 int
161 vhost_auto_index(struct vhost *v, const char *path)
162 {
163 	struct location *loc;
164 
165 	if (v == NULL || path == NULL)
166 		return 0;
167 
168 	loc = TAILQ_FIRST(&v->locations);
169 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
170 		if (loc->auto_index != 0) {
171 			if (matches(loc->match, path))
172 				return loc->auto_index == 1;
173 		}
174 	}
175 
176 	loc = TAILQ_FIRST(&v->locations);
177 	return loc->auto_index == 1;
178 }
179 
180 int
181 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
182 {
183 	struct location *loc;
184 
185 	if (v == NULL || path == NULL)
186 		return 0;
187 
188 	loc = TAILQ_FIRST(&v->locations);
189 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
190 		if (loc->block_code != 0) {
191 			if (matches(loc->match, path)) {
192 				*code = loc->block_code;
193 				*fmt = loc->block_fmt;
194 				return 1;
195 			}
196 		}
197 	}
198 
199 	loc = TAILQ_FIRST(&v->locations);
200 	*code = loc->block_code;
201 	*fmt = loc->block_fmt;
202 	return loc->block_code != 0;
203 }
204 
205 int
206 vhost_dirfd(struct vhost *v, const char *path)
207 {
208 	struct location *loc;
209 
210 	if (v == NULL || path == NULL)
211 		return -1;
212 
213 	loc = TAILQ_FIRST(&v->locations);
214 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
215 		if (loc->dirfd != -1)
216 			if (matches(loc->match, path))
217 				return loc->dirfd;
218 	}
219 
220 	loc = TAILQ_FIRST(&v->locations);
221 	return loc->dirfd;
222 }
223 
224 int
225 vhost_strip(struct vhost *v, const char *path)
226 {
227 	struct location *loc;
228 
229 	if (v == NULL || path == NULL)
230 		return 0;
231 
232 	loc = TAILQ_FIRST(&v->locations);
233 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
234 		if (loc->strip != 0) {
235 			if (matches(loc->match, path))
236 				return loc->strip;
237 		}
238 	}
239 
240 	loc = TAILQ_FIRST(&v->locations);
241 	return loc->strip;
242 }
243 
244 X509_STORE *
245 vhost_require_ca(struct vhost *v, const char *path)
246 {
247 	struct location *loc;
248 
249 	if (v == NULL || path == NULL)
250 		return NULL;
251 
252 	loc = TAILQ_FIRST(&v->locations);
253 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
254 		if (loc->reqca != NULL) {
255 			if (matches(loc->match, path))
256 				return loc->reqca;
257 		}
258 	}
259 
260 	loc = TAILQ_FIRST(&v->locations);
261 	return loc->reqca;
262 }
263 
264 int
265 vhost_disable_log(struct vhost *v, const char *path)
266 {
267 	struct location *loc;
268 
269 	if (v == NULL || path == NULL)
270 		return 0;
271 
272 	loc = TAILQ_FIRST(&v->locations);
273 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
274 		if (loc->disable_log && matches(loc->match, path))
275 				return 1;
276 	}
277 
278 	loc = TAILQ_FIRST(&v->locations);
279 	return loc->disable_log;
280 }
281 
282 static int
283 check_path(struct client *c, const char *path, int *fd)
284 {
285 	struct stat sb;
286 	const char *p;
287 	int flags, dirfd, strip;
288 
289 	assert(path != NULL);
290 
291 	/*
292 	 * in send_dir we add an initial / (to be redirect-friendly),
293 	 * but here we want to skip it
294 	 */
295 	if (*path == '/')
296 		path++;
297 
298 	strip = vhost_strip(c->host, path);
299 	p = strip_path(path, strip);
300 
301 	if (*p == '/')
302 		p = p+1;
303 	if (*p == '\0')
304 		p = ".";
305 
306 	dirfd = vhost_dirfd(c->host, path);
307 	log_debug(c, "check_path: strip=%d path=%s original=%s",
308 	    strip, p, path);
309 	flags = O_RDONLY | O_NOFOLLOW;
310 	if (*fd == -1 && (*fd = openat(dirfd, p, flags)) == -1)
311 		return FILE_MISSING;
312 
313 	if (fstat(*fd, &sb) == -1) {
314 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
315 		return FILE_MISSING;
316 	}
317 
318 	if (S_ISDIR(sb.st_mode))
319 		return FILE_DIRECTORY;
320 
321 	if (sb.st_mode & S_IXUSR)
322 		return FILE_EXECUTABLE;
323 
324 	return FILE_EXISTS;
325 }
326 
327 static void
328 open_file(struct client *c)
329 {
330 	switch (check_path(c, c->iri.path, &c->pfd)) {
331 	case FILE_EXECUTABLE:
332 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
333 			start_cgi(c->iri.path, "", c);
334 			return;
335 		}
336 
337 		/* fallthrough */
338 
339 	case FILE_EXISTS:
340 		c->next = handle_copy;
341 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
342 		return;
343 
344 	case FILE_DIRECTORY:
345 		open_dir(c);
346 		return;
347 
348 	case FILE_MISSING:
349 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
350 			check_for_cgi(c);
351 			return;
352 		}
353 		start_reply(c, NOT_FOUND, "not found");
354 		return;
355 
356 	default:
357 		/* unreachable */
358 		abort();
359 	}
360 }
361 
362 /*
363  * the inverse of this algorithm, i.e. starting from the start of the
364  * path + strlen(cgi), and checking if each component, should be
365  * faster.  But it's tedious to write.  This does the opposite: starts
366  * from the end and strip one component at a time, until either an
367  * executable is found or we emptied the path.
368  */
369 static void
370 check_for_cgi(struct client *c)
371 {
372 	char path[PATH_MAX];
373 	char *end;
374 
375 	strlcpy(path, c->iri.path, sizeof(path));
376 	end = strchr(path, '\0');
377 
378 	while (end > path) {
379 		/* go up one level.  UNIX paths are simple and POSIX
380 		 * dirname, with its ambiguities on if the given path
381 		 * is changed or not, gives me headaches. */
382 		while (*end != '/')
383 			end--;
384 		*end = '\0';
385 
386 		switch (check_path(c, path, &c->pfd)) {
387 		case FILE_EXECUTABLE:
388 			start_cgi(path, end+1, c);
389 			return;
390 		case FILE_MISSING:
391 			break;
392 		default:
393 			goto err;
394 		}
395 
396 		*end = '/';
397 		end--;
398 	}
399 
400 err:
401 	start_reply(c, NOT_FOUND, "not found");
402 	return;
403 }
404 
405 void
406 mark_nonblock(int fd)
407 {
408 	int flags;
409 
410 	if ((flags = fcntl(fd, F_GETFL)) == -1)
411 		fatal("fcntl(F_GETFL): %s", strerror(errno));
412 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
413 		fatal("fcntl(F_SETFL): %s", strerror(errno));
414 }
415 
416 static void
417 handle_handshake(int fd, short ev, void *d)
418 {
419 	struct client *c = d;
420 	struct vhost *h;
421 	struct alist *a;
422 	const char *servname;
423 	const char *parse_err = "unknown error";
424 
425 	switch (tls_handshake(c->ctx)) {
426 	case 0:  /* success */
427 	case -1: /* already handshaked */
428 		break;
429 	case TLS_WANT_POLLIN:
430 		yield_read(fd, c, &handle_handshake);
431 		return;
432 	case TLS_WANT_POLLOUT:
433 		yield_write(fd, c, &handle_handshake);
434 		return;
435 	default:
436 		/* unreachable */
437 		abort();
438 	}
439 
440 	servname = tls_conn_servername(c->ctx);
441 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
442 		log_info(c, "puny_decode: %s", parse_err);
443 		goto err;
444 	}
445 
446 	TAILQ_FOREACH(h, &hosts, vhosts) {
447 		if (matches(h->domain, c->domain))
448 			goto found;
449 		TAILQ_FOREACH(a, &h->aliases, aliases) {
450 			if (matches(a->alias, c->domain))
451 				goto found;
452 		}
453 	}
454 
455 found:
456 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
457 	    servname != NULL ? servname : "(null)",
458 	    c->domain,
459 	    h != NULL ? h->domain : "(null)");
460 
461 	if (h != NULL) {
462 		c->host = h;
463 		handle_open_conn(fd, ev, c);
464 		return;
465 	}
466 
467 err:
468 	if (servname != NULL)
469 		strncpy(c->req, servname, sizeof(c->req));
470 	else
471 		strncpy(c->req, "null", sizeof(c->req));
472 
473 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
474 }
475 
476 static char *
477 strip_path(char *path, int strip)
478 {
479 	char *t;
480 
481 	while (strip > 0) {
482 		if ((t = strchr(path, '/')) == NULL) {
483 			path = strchr(path, '\0');
484 			break;
485 		}
486 		path = t;
487 		strip--;
488 	}
489 
490 	return path;
491 }
492 
493 static void
494 fmt_sbuf(const char *fmt, struct client *c, const char *path)
495 {
496 	size_t i;
497         char buf[32];
498 
499 	memset(buf, 0, sizeof(buf));
500 	for (i = 0; *fmt; ++fmt) {
501 		if (i == sizeof(buf)-1 || *fmt == '%') {
502 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
503 			memset(buf, 0, sizeof(buf));
504 			i = 0;
505 		}
506 
507 		if (*fmt != '%') {
508 			buf[i++] = *fmt;
509 			continue;
510 		}
511 
512 		switch (*++fmt) {
513 		case '%':
514 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
515 			break;
516 		case 'p':
517 			if (*path != '/')
518 				strlcat(c->sbuf, "/", sizeof(c->sbuf));
519 			strlcat(c->sbuf, path, sizeof(c->sbuf));
520 			break;
521 		case 'q':
522 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
523 			break;
524 		case 'P':
525 			snprintf(buf, sizeof(buf), "%d", conf.port);
526 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
527 			memset(buf, 0, sizeof(buf));
528 			break;
529 		case 'N':
530 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
531 			break;
532 		default:
533 			fatal("%s: unknown fmt specifier %c",
534 			    __func__, *fmt);
535 		}
536 	}
537 
538 	if (i != 0)
539 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
540 }
541 
542 /* 1 if a matching `block return' (and apply it), 0 otherwise */
543 static int
544 apply_block_return(struct client *c)
545 {
546 	const char *fmt, *path;
547 	int code;
548 
549 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
550 		return 0;
551 
552 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
553 	fmt_sbuf(fmt, c, path);
554 
555 	start_reply(c, code, c->sbuf);
556 	return 1;
557 }
558 
559 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
560 static int
561 apply_require_ca(struct client *c)
562 {
563 	X509_STORE	*store;
564 	const uint8_t	*cert;
565 	size_t		 len;
566 
567 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
568 		return 0;
569 
570 	if (!tls_peer_cert_provided(c->ctx)) {
571 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
572 		return 1;
573 	}
574 
575 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
576 	if (!validate_against_ca(store, cert, len)) {
577 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
578 		return 1;
579 	}
580 
581 	return 0;
582 }
583 
584 static void
585 handle_open_conn(int fd, short ev, void *d)
586 {
587 	struct client *c = d;
588 	const char *parse_err = "invalid request";
589 	char decoded[DOMAIN_NAME_LEN];
590 
591 	bzero(c->req, sizeof(c->req));
592 	bzero(&c->iri, sizeof(c->iri));
593 
594 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
595 	case -1:
596 		log_err(c, "tls_read: %s", tls_error(c->ctx));
597 		close_conn(fd, ev, c);
598 		return;
599 
600 	case TLS_WANT_POLLIN:
601 		yield_read(fd, c, &handle_open_conn);
602 		return;
603 
604 	case TLS_WANT_POLLOUT:
605 		yield_write(fd, c, &handle_open_conn);
606 		return;
607 	}
608 
609 	if (!trim_req_iri(c->req, &parse_err)
610 	    || !parse_iri(c->req, &c->iri, &parse_err)
611 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
612 		log_info(c, "iri parse error: %s", parse_err);
613 		start_reply(c, BAD_REQUEST, "invalid request");
614 		return;
615 	}
616 
617 	if (c->iri.port_no != conf.port
618 	    || strcmp(c->iri.schema, "gemini")
619 	    || strcmp(decoded, c->domain)) {
620 		start_reply(c, PROXY_REFUSED, "won't proxy request");
621 		return;
622 	}
623 
624 	if (apply_require_ca(c))
625 		return;
626 
627 	if (apply_block_return(c))
628 		return;
629 
630 	if (c->host->entrypoint != NULL) {
631 		start_cgi(c->host->entrypoint, c->iri.path, c);
632 		return;
633 	}
634 
635 	open_file(c);
636 }
637 
638 static void
639 start_reply(struct client *c, int code, const char *meta)
640 {
641 	c->code = code;
642 	c->meta = meta;
643 	handle_start_reply(c->fd, 0, c);
644 }
645 
646 static void
647 handle_start_reply(int fd, short ev, void *d)
648 {
649 	struct client *c = d;
650 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
651 	const char *lang;
652 	size_t len;
653 
654 	lang = vhost_lang(c->host, c->iri.path);
655 
656 	snprintf(buf, sizeof(buf), "%d ", c->code);
657 	strlcat(buf, c->meta, sizeof(buf));
658 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
659 		strlcat(buf, "; lang=", sizeof(buf));
660 		strlcat(buf, lang, sizeof(buf));
661 	}
662 
663 	len = strlcat(buf, "\r\n", sizeof(buf));
664 	assert(len < sizeof(buf));
665 
666 	switch (tls_write(c->ctx, buf, len)) {
667 	case -1:
668 		close_conn(fd, ev, c);
669 		return;
670 	case TLS_WANT_POLLIN:
671 		yield_read(fd, c, &handle_start_reply);
672 		return;
673 	case TLS_WANT_POLLOUT:
674 		yield_write(fd, c, &handle_start_reply);
675 		return;
676 	}
677 
678 	if (!vhost_disable_log(c->host, c->iri.path))
679 		log_request(c, buf, sizeof(buf));
680 
681 	if (c->code != SUCCESS)
682 		close_conn(fd, ev, c);
683 	else
684 		c->next(fd, ev, c);
685 }
686 
687 static size_t
688 host_nth(struct vhost *h)
689 {
690 	struct vhost	*v;
691 	size_t		 i = 0;
692 
693 	TAILQ_FOREACH(v, &hosts, vhosts) {
694 		if (v == h)
695 			return i;
696 		i++;
697 	}
698 
699 	abort();
700 }
701 
702 static void
703 start_cgi(const char *spath, const char *relpath, struct client *c)
704 {
705 	char addr[NI_MAXHOST];
706 	const char *t;
707 	struct cgireq req;
708 	int e;
709 
710 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
711 	    addr, sizeof(addr),
712 	    NULL, 0,
713 	    NI_NUMERICHOST);
714 	if (e != 0)
715 		fatal("getnameinfo failed");
716 
717 	memset(&req, 0, sizeof(req));
718 
719 	memcpy(req.buf, c->req, sizeof(req.buf));
720 
721 	req.iri_schema_off = c->iri.schema - c->req;
722 	req.iri_host_off = c->iri.host - c->req;
723 	req.iri_port_off = c->iri.port - c->req;
724 	req.iri_path_off = c->iri.path - c->req;
725 	req.iri_query_off = c->iri.query - c->req;
726 	req.iri_fragment_off = c->iri.fragment - c->req;
727 
728 	req.iri_portno = c->iri.port_no;
729 
730 	strlcpy(req.spath, spath, sizeof(req.spath));
731 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
732 	strlcpy(req.addr, addr, sizeof(req.addr));
733 
734 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
735 		strlcpy(req.subject, t, sizeof(req.subject));
736 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
737 		strlcpy(req.issuer, t, sizeof(req.issuer));
738 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
739 		strlcpy(req.hash, t, sizeof(req.hash));
740 	if ((t = tls_conn_version(c->ctx)) != NULL)
741 		strlcpy(req.version, t, sizeof(req.version));
742 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
743 		strlcpy(req.cipher, t, sizeof(req.cipher));
744 
745 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
746 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
747 	req.notafter = tls_peer_cert_notafter(c->ctx);
748 
749 	req.host_off = host_nth(c->host);
750 
751 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
752 	imsg_flush(&exibuf);
753 
754 	close(c->pfd);
755 }
756 
757 static void
758 open_dir(struct client *c)
759 {
760 	size_t len;
761 	int dirfd, root;
762 	char *before_file;
763 
764 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
765 
766 	len = strlen(c->iri.path);
767 	if (len > 0 && !ends_with(c->iri.path, "/")) {
768 		redirect_canonical_dir(c);
769 		return;
770 	}
771 
772 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
773 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
774 	if (!ends_with(c->sbuf, "/"))
775 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
776 	before_file = strchr(c->sbuf, '\0');
777 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
778 	    sizeof(c->sbuf));
779 	if (len >= sizeof(c->sbuf)) {
780 		start_reply(c, TEMP_FAILURE, "internal server error");
781 		return;
782 	}
783 
784 	c->iri.path = c->sbuf;
785 
786 	/* close later unless we have to generate the dir listing */
787 	dirfd = c->pfd;
788 	c->pfd = -1;
789 
790 	switch (check_path(c, c->iri.path, &c->pfd)) {
791 	case FILE_EXECUTABLE:
792 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
793 			start_cgi(c->iri.path, "", c);
794 			break;
795 		}
796 
797 		/* fallthrough */
798 
799 	case FILE_EXISTS:
800 		c->next = handle_copy;
801 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
802 		break;
803 
804 	case FILE_DIRECTORY:
805 		start_reply(c, TEMP_REDIRECT, c->sbuf);
806 		break;
807 
808 	case FILE_MISSING:
809 		*before_file = '\0';
810 
811 		if (!vhost_auto_index(c->host, c->iri.path)) {
812 			start_reply(c, NOT_FOUND, "not found");
813 			break;
814 		}
815 
816 		c->next = enter_handle_dirlist;
817 
818 		c->dirlen = scandir_fd(dirfd, &c->dir,
819 		    root ? select_non_dotdot : select_non_dot,
820 		    alphasort);
821 		if (c->dirlen == -1) {
822 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
823 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
824 			start_reply(c, TEMP_FAILURE, "internal server error");
825 			return;
826 		}
827 		c->diroff = 0;
828 		c->off = 0;
829 
830                 start_reply(c, SUCCESS, "text/gemini");
831 		return;
832 
833 	default:
834 		/* unreachable */
835 		abort();
836 	}
837 
838 	close(dirfd);
839 }
840 
841 static void
842 redirect_canonical_dir(struct client *c)
843 {
844 	size_t len;
845 
846 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
847 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
848 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
849 
850 	if (len >= sizeof(c->sbuf)) {
851 		start_reply(c, TEMP_FAILURE, "internal server error");
852 		return;
853 	}
854 
855 	start_reply(c, TEMP_REDIRECT, c->sbuf);
856 }
857 
858 static void
859 enter_handle_dirlist(int fd, short ev, void *d)
860 {
861 	struct client *c = d;
862 	char b[PATH_MAX];
863 	size_t l;
864 
865 	strlcpy(b, c->iri.path, sizeof(b));
866 	l = snprintf(c->sbuf, sizeof(c->sbuf),
867 	    "# Index of %s\n\n", b);
868 	if (l >= sizeof(c->sbuf)) {
869 		/* this is impossible, given that we have enough space
870 		 * in c->sbuf to hold the ancilliary string plus the
871 		 * full path; but it wouldn't read nice without some
872 		 * error checking, and I'd like to avoid a strlen. */
873 		close_conn(fd, ev, c);
874 		return;
875 	}
876 
877 	c->len = l;
878 	handle_dirlist(fd, ev, c);
879 }
880 
881 static void
882 handle_dirlist(int fd, short ev, void *d)
883 {
884 	struct client *c = d;
885 	ssize_t r;
886 
887 	while (c->len > 0) {
888 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
889 		case -1:
890 			close_conn(fd, ev, c);
891 			return;
892 		case TLS_WANT_POLLOUT:
893 			yield_read(fd, c, &handle_dirlist);
894 			return;
895 		case TLS_WANT_POLLIN:
896 			yield_write(fd, c, &handle_dirlist);
897 			return;
898 		default:
899 			c->off += r;
900 			c->len -= r;
901 		}
902 	}
903 
904 	send_directory_listing(fd, ev, c);
905 }
906 
907 static int
908 read_next_dir_entry(struct client *c)
909 {
910 	if (c->diroff == c->dirlen)
911 		return 0;
912 
913 	/* XXX: url escape */
914 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s\n",
915 	    c->dir[c->diroff]->d_name);
916 
917 	free(c->dir[c->diroff]);
918 	c->diroff++;
919 
920 	c->len = strlen(c->sbuf);
921 	c->off = 0;
922 	return 1;
923 }
924 
925 static void
926 send_directory_listing(int fd, short ev, void *d)
927 {
928 	struct client *c = d;
929 	ssize_t r;
930 
931 	while (1) {
932 		if (c->len == 0) {
933 			if (!read_next_dir_entry(c))
934 				goto end;
935 		}
936 
937 		while (c->len > 0) {
938 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
939 			case -1:
940 				goto end;
941 
942 			case TLS_WANT_POLLOUT:
943 				yield_read(fd, c, &send_directory_listing);
944 				return;
945 
946 			case TLS_WANT_POLLIN:
947 				yield_write(fd, c, &send_directory_listing);
948 				return;
949 
950 			default:
951 				c->off += r;
952 				c->len -= r;
953 				break;
954 			}
955 		}
956 	}
957 
958 end:
959 	close_conn(fd, ev, d);
960 }
961 
962 /* accumulate the meta line from the cgi script. */
963 static void
964 handle_cgi_reply(int fd, short ev, void *d)
965 {
966 	struct client *c = d;
967 	void	*buf, *e;
968 	size_t	 len;
969 	ssize_t	 r;
970 
971 
972 	buf = c->sbuf + c->len;
973 	len = sizeof(c->sbuf) - c->len;
974 
975 	r = read(c->pfd, buf, len);
976 	if (r == 0 || r == -1) {
977 		start_reply(c, CGI_ERROR, "CGI error");
978 		return;
979 	}
980 
981 	c->len += r;
982 
983 	/* TODO: error if the CGI script don't reply correctly */
984 	e = strchr(c->sbuf, '\n');
985 	if (e != NULL || c->len == sizeof(c->sbuf)) {
986 		log_request(c, c->sbuf, c->len);
987 
988 		c->off = 0;
989 		handle_copy(fd, ev, c);
990 		return;
991 	}
992 
993 	yield_read(fd, c, &handle_cgi_reply);
994 }
995 
996 static void
997 handle_copy(int fd, short ev, void *d)
998 {
999 	struct client *c = d;
1000 	ssize_t r;
1001 
1002 	while (1) {
1003 		while (c->len > 0) {
1004 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
1005 			case -1:
1006 				goto end;
1007 
1008 			case TLS_WANT_POLLOUT:
1009 				yield_write(c->fd, c, &handle_copy);
1010 				return;
1011 
1012 			case TLS_WANT_POLLIN:
1013 				yield_read(c->fd, c, &handle_copy);
1014 				return;
1015 
1016 			default:
1017                                 c->off += r;
1018 				c->len -= r;
1019 				break;
1020 			}
1021 		}
1022 
1023 		switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
1024 		case 0:
1025 			goto end;
1026 		case -1:
1027 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
1028 				yield_read(c->pfd, c, &handle_copy);
1029 				return;
1030 			}
1031 			goto end;
1032 		default:
1033 			c->len = r;
1034 			c->off = 0;
1035 		}
1036 	}
1037 
1038 end:
1039 	close_conn(c->fd, ev, d);
1040 }
1041 
1042 static void
1043 close_conn(int fd, short ev, void *d)
1044 {
1045 	struct client *c = d;
1046 
1047 	switch (tls_close(c->ctx)) {
1048 	case TLS_WANT_POLLIN:
1049 		yield_read(fd, c, &close_conn);
1050 		return;
1051 	case TLS_WANT_POLLOUT:
1052 		yield_read(fd, c, &close_conn);
1053 		return;
1054 	}
1055 
1056 	connected_clients--;
1057 
1058 	tls_free(c->ctx);
1059 	c->ctx = NULL;
1060 
1061 	if (c->pfd != -1)
1062 		close(c->pfd);
1063 
1064 	if (c->dir != NULL)
1065 		free(c->dir);
1066 
1067 	close(c->fd);
1068 	c->fd = -1;
1069 }
1070 
1071 static void
1072 do_accept(int sock, short et, void *d)
1073 {
1074 	struct client *c;
1075 	struct sockaddr_storage addr;
1076 	struct sockaddr *saddr;
1077 	socklen_t len;
1078 	int i, fd;
1079 
1080 	(void)et;
1081 
1082 	saddr = (struct sockaddr*)&addr;
1083 	len = sizeof(addr);
1084 	if ((fd = accept(sock, saddr, &len)) == -1) {
1085 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1086 			return;
1087 		fatal("accept: %s", strerror(errno));
1088 	}
1089 
1090 	mark_nonblock(fd);
1091 
1092 	for (i = 0; i < MAX_USERS; ++i) {
1093 		c = &clients[i];
1094 		if (c->fd == -1) {
1095 			memset(c, 0, sizeof(*c));
1096 			c->id = i;
1097 			if (tls_accept_socket(ctx, &c->ctx, fd) == -1)
1098 				break; /* goodbye fd! */
1099 
1100 			c->fd = fd;
1101 			c->pfd = -1;
1102 			c->dir = NULL;
1103 			c->addr = addr;
1104 
1105 			yield_read(fd, c, &handle_handshake);
1106 			connected_clients++;
1107 			return;
1108 		}
1109 	}
1110 
1111 	close(fd);
1112 }
1113 
1114 struct client *
1115 client_by_id(int id)
1116 {
1117 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1118 		fatal("in client_by_id: invalid id %d", id);
1119 	return &clients[id];
1120 }
1121 
1122 static void
1123 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1124 {
1125 	struct client *c;
1126 
1127 	c = client_by_id(imsg->hdr.peerid);
1128 
1129 	if ((c->pfd = imsg->fd) == -1)
1130 		start_reply(c, TEMP_FAILURE, "internal server error");
1131 	else
1132 		yield_read(c->pfd, c, &handle_cgi_reply);
1133 }
1134 
1135 static void
1136 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1137 {
1138 	(void)imsg;
1139 	(void)len;
1140 
1141 	/* don't call event_loopbreak since we want to finish to
1142 	 * handle the ongoing connections. */
1143 
1144 	event_del(&e4);
1145 	if (has_ipv6)
1146 		event_del(&e6);
1147 	if (has_siginfo)
1148 		signal_del(&siginfo);
1149 	event_del(&imsgev);
1150 	signal_del(&sigusr2);
1151 }
1152 
1153 static void
1154 handle_dispatch_imsg(int fd, short ev, void *d)
1155 {
1156 	struct imsgbuf *ibuf = d;
1157 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1158 }
1159 
1160 static void
1161 handle_siginfo(int fd, short ev, void *d)
1162 {
1163 	(void)fd;
1164 	(void)ev;
1165 	(void)d;
1166 
1167 	log_info(NULL, "%d connected clients", connected_clients);
1168 }
1169 
1170 void
1171 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1172 {
1173 	size_t i;
1174 
1175 	ctx = ctx_;
1176 
1177 	event_init();
1178 
1179 	memset(&clients, 0, sizeof(clients));
1180 	for (i = 0; i < MAX_USERS; ++i)
1181 		clients[i].fd = -1;
1182 
1183 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1184 	event_add(&e4, NULL);
1185 
1186 	if (sock6 != -1) {
1187 		has_ipv6 = 1;
1188 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1189 		event_add(&e6, NULL);
1190 	}
1191 
1192 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1193 	event_add(&imsgev, NULL);
1194 
1195 #ifdef SIGINFO
1196 	has_siginfo = 1;
1197 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1198 	signal_add(&siginfo, NULL);
1199 #endif
1200 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1201 	signal_add(&sigusr2, NULL);
1202 
1203 	sandbox_server_process();
1204 	event_dispatch();
1205 	_exit(0);
1206 }