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 int shutting_down;
30 
31 struct client	 clients[MAX_USERS];
32 
33 static struct tls	*ctx;
34 
35 static struct event e4, e6, imsgev, siginfo, sigusr2;
36 static int has_ipv6, has_siginfo;
37 
38 int connected_clients;
39 
40 static inline int matches(const char*, const char*);
41 
42 static inline void yield_read(int, struct client*, statefn);
43 static inline void yield_write(int, struct client*, statefn);
44 
45 static int	 check_path(struct client*, const char*, int*);
46 static void	 open_file(struct client*);
47 static void	 check_for_cgi(struct client*);
48 static void	 handle_handshake(int, short, void*);
49 static const char *strip_path(const char*, int);
50 static void	 fmt_sbuf(const char*, struct client*, const char*);
51 static int	 apply_block_return(struct client*);
52 static int	 apply_require_ca(struct client*);
53 static void	 handle_open_conn(int, short, void*);
54 static void	 handle_start_reply(int, short, void*);
55 static size_t	 host_nth(struct vhost*);
56 static void	 start_cgi(const char*, const char*, struct client*);
57 static void	 open_dir(struct client*);
58 static void	 redirect_canonical_dir(struct client*);
59 static void	 enter_handle_dirlist(int, short, void*);
60 static void	 handle_dirlist(int, short, void*);
61 static int 	 read_next_dir_entry(struct client*);
62 static void	 send_directory_listing(int, short, void*);
63 static void	 handle_cgi_reply(int, short, void*);
64 static void	 handle_copy(int, short, void*);
65 static void	 do_accept(int, short, void*);
66 static void	 handle_imsg_cgi_res(struct imsgbuf*, struct imsg*, size_t);
67 static void	 handle_imsg_fcgi_fd(struct imsgbuf*, struct imsg*, size_t);
68 static void	 handle_imsg_quit(struct imsgbuf*, struct imsg*, size_t);
69 static void	 handle_siginfo(int, short, void*);
70 
71 static imsg_handlerfn *handlers[] = {
72 	[IMSG_QUIT] = handle_imsg_quit,
73 	[IMSG_CGI_RES] = handle_imsg_cgi_res,
74 	[IMSG_FCGI_FD] = handle_imsg_fcgi_fd,
75 };
76 
77 static inline int
78 matches(const char *pattern, const char *path)
79 {
80 	if (*path == '/')
81 		path++;
82 	return !fnmatch(pattern, path, 0);
83 }
84 
85 static inline void
86 yield_read(int fd, struct client *c, statefn fn)
87 {
88 	event_once(fd, EV_READ, fn, c, NULL);
89 }
90 
91 static inline void
92 yield_write(int fd, struct client *c, statefn fn)
93 {
94 	event_once(fd, EV_WRITE, fn, c, NULL);
95 }
96 
97 const char *
98 vhost_lang(struct vhost *v, const char *path)
99 {
100 	struct location *loc;
101 
102 	if (v == NULL || path == NULL)
103 		return NULL;
104 
105 	loc = TAILQ_FIRST(&v->locations);
106 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
107 		if (loc->lang != NULL) {
108 			if (matches(loc->match, path))
109 				return loc->lang;
110 		}
111 	}
112 
113 	return TAILQ_FIRST(&v->locations)->lang;
114 }
115 
116 const char *
117 vhost_default_mime(struct vhost *v, const char *path)
118 {
119 	struct location *loc;
120 	const char *default_mime = "application/octet-stream";
121 
122 	if (v == NULL || path == NULL)
123 		return default_mime;
124 
125 	loc = TAILQ_FIRST(&v->locations);
126 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
127 		if (loc->default_mime != NULL) {
128 			if (matches(loc->match, path))
129 				return loc->default_mime;
130 		}
131 	}
132 
133 	loc = TAILQ_FIRST(&v->locations);
134 	if (loc->default_mime != NULL)
135 		return loc->default_mime;
136 	return default_mime;
137 }
138 
139 const char *
140 vhost_index(struct vhost *v, const char *path)
141 {
142 	struct location *loc;
143 	const char *index = "index.gmi";
144 
145 	if (v == NULL || path == NULL)
146 		return index;
147 
148 	loc = TAILQ_FIRST(&v->locations);
149 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
150 		if (loc->index != NULL) {
151 			if (matches(loc->match, path))
152 				return loc->index;
153 		}
154 	}
155 
156 	loc = TAILQ_FIRST(&v->locations);
157 	if (loc->index != NULL)
158 		return loc->index;
159 	return index;
160 }
161 
162 int
163 vhost_auto_index(struct vhost *v, const char *path)
164 {
165 	struct location *loc;
166 
167 	if (v == NULL || path == NULL)
168 		return 0;
169 
170 	loc = TAILQ_FIRST(&v->locations);
171 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
172 		if (loc->auto_index != 0) {
173 			if (matches(loc->match, path))
174 				return loc->auto_index == 1;
175 		}
176 	}
177 
178 	loc = TAILQ_FIRST(&v->locations);
179 	return loc->auto_index == 1;
180 }
181 
182 int
183 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
184 {
185 	struct location *loc;
186 
187 	if (v == NULL || path == NULL)
188 		return 0;
189 
190 	loc = TAILQ_FIRST(&v->locations);
191 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
192 		if (loc->block_code != 0) {
193 			if (matches(loc->match, path)) {
194 				*code = loc->block_code;
195 				*fmt = loc->block_fmt;
196 				return 1;
197 			}
198 		}
199 	}
200 
201 	loc = TAILQ_FIRST(&v->locations);
202 	*code = loc->block_code;
203 	*fmt = loc->block_fmt;
204 	return loc->block_code != 0;
205 }
206 
207 int
208 vhost_fastcgi(struct vhost *v, const char *path)
209 {
210 	struct location *loc;
211 
212 	if (v == NULL || path == NULL)
213 		return -1;
214 
215 	loc = TAILQ_FIRST(&v->locations);
216 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
217 		if (loc->fcgi != -1)
218 			if (matches(loc->match, path))
219 				return loc->fcgi;
220 	}
221 
222 	loc = TAILQ_FIRST(&v->locations);
223 	return loc->fcgi;
224 }
225 
226 int
227 vhost_dirfd(struct vhost *v, const char *path, size_t *retloc)
228 {
229 	struct location *loc;
230 	size_t		 l = 0;
231 
232 	if (v == NULL || path == NULL)
233 		return -1;
234 
235 	loc = TAILQ_FIRST(&v->locations);
236 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
237 		l++;
238 		if (loc->dirfd != -1)
239 			if (matches(loc->match, path)) {
240 				*retloc = l;
241 				return loc->dirfd;
242 			}
243 	}
244 
245 	*retloc = 0;
246 	loc = TAILQ_FIRST(&v->locations);
247 	return loc->dirfd;
248 }
249 
250 int
251 vhost_strip(struct vhost *v, const char *path)
252 {
253 	struct location *loc;
254 
255 	if (v == NULL || path == NULL)
256 		return 0;
257 
258 	loc = TAILQ_FIRST(&v->locations);
259 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
260 		if (loc->strip != 0) {
261 			if (matches(loc->match, path))
262 				return loc->strip;
263 		}
264 	}
265 
266 	loc = TAILQ_FIRST(&v->locations);
267 	return loc->strip;
268 }
269 
270 X509_STORE *
271 vhost_require_ca(struct vhost *v, const char *path)
272 {
273 	struct location *loc;
274 
275 	if (v == NULL || path == NULL)
276 		return NULL;
277 
278 	loc = TAILQ_FIRST(&v->locations);
279 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
280 		if (loc->reqca != NULL) {
281 			if (matches(loc->match, path))
282 				return loc->reqca;
283 		}
284 	}
285 
286 	loc = TAILQ_FIRST(&v->locations);
287 	return loc->reqca;
288 }
289 
290 int
291 vhost_disable_log(struct vhost *v, const char *path)
292 {
293 	struct location *loc;
294 
295 	if (v == NULL || path == NULL)
296 		return 0;
297 
298 	loc = TAILQ_FIRST(&v->locations);
299 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
300 		if (loc->disable_log && matches(loc->match, path))
301 				return 1;
302 	}
303 
304 	loc = TAILQ_FIRST(&v->locations);
305 	return loc->disable_log;
306 }
307 
308 static int
309 check_path(struct client *c, const char *path, int *fd)
310 {
311 	struct stat sb;
312 	const char *p;
313 	int dirfd, strip;
314 
315 	assert(path != NULL);
316 
317 	/*
318 	 * in send_dir we add an initial / (to be redirect-friendly),
319 	 * but here we want to skip it
320 	 */
321 	if (*path == '/')
322 		path++;
323 
324 	strip = vhost_strip(c->host, path);
325 	p = strip_path(path, strip);
326 
327 	if (*p == '/')
328 		p = p+1;
329 	if (*p == '\0')
330 		p = ".";
331 
332 	dirfd = vhost_dirfd(c->host, path, &c->loc);
333 	log_debug(c, "check_path: strip=%d path=%s original=%s",
334 	    strip, p, path);
335 	if (*fd == -1 && (*fd = openat(dirfd, p, O_RDONLY)) == -1)
336 		return FILE_MISSING;
337 
338 	if (fstat(*fd, &sb) == -1) {
339 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
340 		return FILE_MISSING;
341 	}
342 
343 	if (S_ISDIR(sb.st_mode))
344 		return FILE_DIRECTORY;
345 
346 	if (sb.st_mode & S_IXUSR)
347 		return FILE_EXECUTABLE;
348 
349 	return FILE_EXISTS;
350 }
351 
352 static void
353 open_file(struct client *c)
354 {
355 	switch (check_path(c, c->iri.path, &c->pfd)) {
356 	case FILE_EXECUTABLE:
357 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
358 			start_cgi(c->iri.path, "", c);
359 			return;
360 		}
361 
362 		/* fallthrough */
363 
364 	case FILE_EXISTS:
365 		c->next = handle_copy;
366 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
367 		return;
368 
369 	case FILE_DIRECTORY:
370 		open_dir(c);
371 		return;
372 
373 	case FILE_MISSING:
374 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
375 			check_for_cgi(c);
376 			return;
377 		}
378 		start_reply(c, NOT_FOUND, "not found");
379 		return;
380 
381 	default:
382 		/* unreachable */
383 		abort();
384 	}
385 }
386 
387 /*
388  * the inverse of this algorithm, i.e. starting from the start of the
389  * path + strlen(cgi), and checking if each component, should be
390  * faster.  But it's tedious to write.  This does the opposite: starts
391  * from the end and strip one component at a time, until either an
392  * executable is found or we emptied the path.
393  */
394 static void
395 check_for_cgi(struct client *c)
396 {
397 	char path[PATH_MAX];
398 	char *end;
399 
400 	strlcpy(path, c->iri.path, sizeof(path));
401 	end = strchr(path, '\0');
402 
403 	while (end > path) {
404 		/*
405 		 * go up one level.  UNIX paths are simple and POSIX
406 		 * dirname, with its ambiguities on if the given
407 		 * pointer is changed or not, gives me headaches.
408 		 */
409 		while (*end != '/')
410 			end--;
411 		*end = '\0';
412 
413 		switch (check_path(c, path, &c->pfd)) {
414 		case FILE_EXECUTABLE:
415 			start_cgi(path, end+1, c);
416 			return;
417 		case FILE_MISSING:
418 			break;
419 		default:
420 			goto err;
421 		}
422 
423 		*end = '/';
424 		end--;
425 	}
426 
427 err:
428 	start_reply(c, NOT_FOUND, "not found");
429 	return;
430 }
431 
432 void
433 mark_nonblock(int fd)
434 {
435 	int flags;
436 
437 	if ((flags = fcntl(fd, F_GETFL)) == -1)
438 		fatal("fcntl(F_GETFL): %s", strerror(errno));
439 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
440 		fatal("fcntl(F_SETFL): %s", strerror(errno));
441 }
442 
443 static void
444 handle_handshake(int fd, short ev, void *d)
445 {
446 	struct client *c = d;
447 	struct vhost *h;
448 	struct alist *a;
449 	const char *servname;
450 	const char *parse_err = "unknown error";
451 
452 	switch (tls_handshake(c->ctx)) {
453 	case 0:  /* success */
454 	case -1: /* already handshaked */
455 		break;
456 	case TLS_WANT_POLLIN:
457 		yield_read(fd, c, &handle_handshake);
458 		return;
459 	case TLS_WANT_POLLOUT:
460 		yield_write(fd, c, &handle_handshake);
461 		return;
462 	default:
463 		/* unreachable */
464 		abort();
465 	}
466 
467 	servname = tls_conn_servername(c->ctx);
468 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
469 		log_info(c, "puny_decode: %s", parse_err);
470 		goto err;
471 	}
472 
473 	TAILQ_FOREACH(h, &hosts, vhosts) {
474 		if (matches(h->domain, c->domain))
475 			goto found;
476 		TAILQ_FOREACH(a, &h->aliases, aliases) {
477 			if (matches(a->alias, c->domain))
478 				goto found;
479 		}
480 	}
481 
482 found:
483 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
484 	    servname != NULL ? servname : "(null)",
485 	    c->domain,
486 	    h != NULL ? h->domain : "(null)");
487 
488 	if (h != NULL) {
489 		c->host = h;
490 		handle_open_conn(fd, ev, c);
491 		return;
492 	}
493 
494 err:
495 	if (servname != NULL)
496 		strlcpy(c->req, servname, sizeof(c->req));
497 	else
498 		strlcpy(c->req, "null", sizeof(c->req));
499 
500 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
501 }
502 
503 static const char *
504 strip_path(const char *path, int strip)
505 {
506 	char *t;
507 
508 	while (strip > 0) {
509 		if ((t = strchr(path, '/')) == NULL) {
510 			path = strchr(path, '\0');
511 			break;
512 		}
513 		path = t;
514 		strip--;
515 	}
516 
517 	return path;
518 }
519 
520 static void
521 fmt_sbuf(const char *fmt, struct client *c, const char *path)
522 {
523 	size_t i;
524         char buf[32];
525 
526 	memset(buf, 0, sizeof(buf));
527 	for (i = 0; *fmt; ++fmt) {
528 		if (i == sizeof(buf)-1 || *fmt == '%') {
529 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
530 			memset(buf, 0, sizeof(buf));
531 			i = 0;
532 		}
533 
534 		if (*fmt != '%') {
535 			buf[i++] = *fmt;
536 			continue;
537 		}
538 
539 		switch (*++fmt) {
540 		case '%':
541 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
542 			break;
543 		case 'p':
544 			if (*path != '/')
545 				strlcat(c->sbuf, "/", sizeof(c->sbuf));
546 			strlcat(c->sbuf, path, sizeof(c->sbuf));
547 			break;
548 		case 'q':
549 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
550 			break;
551 		case 'P':
552 			snprintf(buf, sizeof(buf), "%d", conf.port);
553 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
554 			memset(buf, 0, sizeof(buf));
555 			break;
556 		case 'N':
557 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
558 			break;
559 		default:
560 			fatal("%s: unknown fmt specifier %c",
561 			    __func__, *fmt);
562 		}
563 	}
564 
565 	if (i != 0)
566 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
567 }
568 
569 /* 1 if a matching `block return' (and apply it), 0 otherwise */
570 static int
571 apply_block_return(struct client *c)
572 {
573 	const char *fmt, *path;
574 	int code;
575 
576 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
577 		return 0;
578 
579 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
580 	fmt_sbuf(fmt, c, path);
581 
582 	start_reply(c, code, c->sbuf);
583 	return 1;
584 }
585 
586 /* 1 if matching `fcgi' (and apply it), 0 otherwise */
587 static int
588 apply_fastcgi(struct client *c)
589 {
590 	int		 id;
591 	struct fcgi	*f;
592 
593 	if ((id = vhost_fastcgi(c->host, c->iri.path)) == -1)
594 		return 0;
595 
596 	switch ((f = &fcgi[id])->s) {
597 	case FCGI_OFF:
598 		f->s = FCGI_INFLIGHT;
599 		log_info(c, "opening fastcgi connection for (%s,%s,%s)",
600 		    f->path, f->port, f->prog);
601 		imsg_compose(&exibuf, IMSG_FCGI_REQ, 0, 0, -1,
602 		    &id, sizeof(id));
603 		imsg_flush(&exibuf);
604                 /* fallthrough */
605 	case FCGI_INFLIGHT:
606                 c->fcgi = id;
607 		break;
608 	case FCGI_READY:
609                 c->fcgi = id;
610 		send_fcgi_req(f, c);
611 		break;
612 	}
613 
614 	return 1;
615 }
616 
617 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
618 static int
619 apply_require_ca(struct client *c)
620 {
621 	X509_STORE	*store;
622 	const uint8_t	*cert;
623 	size_t		 len;
624 
625 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
626 		return 0;
627 
628 	if (!tls_peer_cert_provided(c->ctx)) {
629 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
630 		return 1;
631 	}
632 
633 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
634 	if (!validate_against_ca(store, cert, len)) {
635 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
636 		return 1;
637 	}
638 
639 	return 0;
640 }
641 
642 static void
643 handle_open_conn(int fd, short ev, void *d)
644 {
645 	struct client *c = d;
646 	const char *parse_err = "invalid request";
647 	char decoded[DOMAIN_NAME_LEN];
648 
649 	bzero(c->req, sizeof(c->req));
650 	bzero(&c->iri, sizeof(c->iri));
651 
652 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
653 	case -1:
654 		log_err(c, "tls_read: %s", tls_error(c->ctx));
655 		close_conn(fd, ev, c);
656 		return;
657 
658 	case TLS_WANT_POLLIN:
659 		yield_read(fd, c, &handle_open_conn);
660 		return;
661 
662 	case TLS_WANT_POLLOUT:
663 		yield_write(fd, c, &handle_open_conn);
664 		return;
665 	}
666 
667 	if (!trim_req_iri(c->req, &parse_err)
668 	    || !parse_iri(c->req, &c->iri, &parse_err)
669 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
670 		log_info(c, "iri parse error: %s", parse_err);
671 		start_reply(c, BAD_REQUEST, "invalid request");
672 		return;
673 	}
674 
675 	if (c->iri.port_no != conf.port
676 	    || strcmp(c->iri.schema, "gemini")
677 	    || strcmp(decoded, c->domain)) {
678 		start_reply(c, PROXY_REFUSED, "won't proxy request");
679 		return;
680 	}
681 
682 	if (apply_require_ca(c))
683 		return;
684 
685 	if (apply_block_return(c))
686 		return;
687 
688 	if (apply_fastcgi(c))
689 		return;
690 
691 	if (c->host->entrypoint != NULL) {
692 		c->loc = 0;
693 		start_cgi(c->host->entrypoint, c->iri.path, c);
694 		return;
695 	}
696 
697 	open_file(c);
698 }
699 
700 void
701 start_reply(struct client *c, int code, const char *meta)
702 {
703 	c->code = code;
704 	c->meta = meta;
705 	handle_start_reply(c->fd, 0, c);
706 }
707 
708 static void
709 handle_start_reply(int fd, short ev, void *d)
710 {
711 	struct client *c = d;
712 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
713 	const char *lang;
714 	size_t len;
715 
716 	lang = vhost_lang(c->host, c->iri.path);
717 
718 	snprintf(buf, sizeof(buf), "%d ", c->code);
719 	strlcat(buf, c->meta, sizeof(buf));
720 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
721 		strlcat(buf, "; lang=", sizeof(buf));
722 		strlcat(buf, lang, sizeof(buf));
723 	}
724 
725 	len = strlcat(buf, "\r\n", sizeof(buf));
726 	assert(len < sizeof(buf));
727 
728 	switch (tls_write(c->ctx, buf, len)) {
729 	case -1:
730 		close_conn(fd, ev, c);
731 		return;
732 	case TLS_WANT_POLLIN:
733 		yield_read(fd, c, &handle_start_reply);
734 		return;
735 	case TLS_WANT_POLLOUT:
736 		yield_write(fd, c, &handle_start_reply);
737 		return;
738 	}
739 
740 	if (!vhost_disable_log(c->host, c->iri.path))
741 		log_request(c, buf, sizeof(buf));
742 
743 	if (c->code != SUCCESS)
744 		close_conn(fd, ev, c);
745 	else
746 		c->next(fd, ev, c);
747 }
748 
749 static size_t
750 host_nth(struct vhost *h)
751 {
752 	struct vhost	*v;
753 	size_t		 i = 0;
754 
755 	TAILQ_FOREACH(v, &hosts, vhosts) {
756 		if (v == h)
757 			return i;
758 		i++;
759 	}
760 
761 	abort();
762 }
763 
764 static void
765 start_cgi(const char *spath, const char *relpath, struct client *c)
766 {
767 	char addr[NI_MAXHOST];
768 	const char *t;
769 	struct cgireq req;
770 	int e;
771 
772 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
773 	    addr, sizeof(addr),
774 	    NULL, 0,
775 	    NI_NUMERICHOST);
776 	if (e != 0)
777 		fatal("getnameinfo failed");
778 
779 	memset(&req, 0, sizeof(req));
780 
781 	memcpy(req.buf, c->req, sizeof(req.buf));
782 
783 	req.iri_schema_off = c->iri.schema - c->req;
784 	req.iri_host_off = c->iri.host - c->req;
785 	req.iri_port_off = c->iri.port - c->req;
786 	req.iri_path_off = c->iri.path - c->req;
787 	req.iri_query_off = c->iri.query - c->req;
788 	req.iri_fragment_off = c->iri.fragment - c->req;
789 
790 	req.iri_portno = c->iri.port_no;
791 
792 	strlcpy(req.spath, spath, sizeof(req.spath));
793 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
794 	strlcpy(req.addr, addr, sizeof(req.addr));
795 
796 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
797 		strlcpy(req.subject, t, sizeof(req.subject));
798 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
799 		strlcpy(req.issuer, t, sizeof(req.issuer));
800 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
801 		strlcpy(req.hash, t, sizeof(req.hash));
802 	if ((t = tls_conn_version(c->ctx)) != NULL)
803 		strlcpy(req.version, t, sizeof(req.version));
804 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
805 		strlcpy(req.cipher, t, sizeof(req.cipher));
806 
807 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
808 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
809 	req.notafter = tls_peer_cert_notafter(c->ctx);
810 
811 	req.host_off = host_nth(c->host);
812 	req.loc_off = c->loc;
813 
814 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
815 	imsg_flush(&exibuf);
816 
817 	close(c->pfd);
818 }
819 
820 static void
821 open_dir(struct client *c)
822 {
823 	size_t len;
824 	int dirfd, root;
825 	char *before_file;
826 
827 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
828 
829 	len = strlen(c->iri.path);
830 	if (len > 0 && !ends_with(c->iri.path, "/")) {
831 		redirect_canonical_dir(c);
832 		return;
833 	}
834 
835 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
836 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
837 	if (!ends_with(c->sbuf, "/"))
838 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
839 	before_file = strchr(c->sbuf, '\0');
840 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
841 	    sizeof(c->sbuf));
842 	if (len >= sizeof(c->sbuf)) {
843 		start_reply(c, TEMP_FAILURE, "internal server error");
844 		return;
845 	}
846 
847 	c->iri.path = c->sbuf;
848 
849 	/* close later unless we have to generate the dir listing */
850 	dirfd = c->pfd;
851 	c->pfd = -1;
852 
853 	switch (check_path(c, c->iri.path, &c->pfd)) {
854 	case FILE_EXECUTABLE:
855 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
856 			start_cgi(c->iri.path, "", c);
857 			break;
858 		}
859 
860 		/* fallthrough */
861 
862 	case FILE_EXISTS:
863 		c->next = handle_copy;
864 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
865 		break;
866 
867 	case FILE_DIRECTORY:
868 		start_reply(c, TEMP_REDIRECT, c->sbuf);
869 		break;
870 
871 	case FILE_MISSING:
872 		*before_file = '\0';
873 
874 		if (!vhost_auto_index(c->host, c->iri.path)) {
875 			start_reply(c, NOT_FOUND, "not found");
876 			break;
877 		}
878 
879 		c->next = enter_handle_dirlist;
880 
881 		c->dirlen = scandir_fd(dirfd, &c->dir,
882 		    root ? select_non_dotdot : select_non_dot,
883 		    alphasort);
884 		if (c->dirlen == -1) {
885 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
886 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
887 			start_reply(c, TEMP_FAILURE, "internal server error");
888 			return;
889 		}
890 		c->diroff = 0;
891 		c->off = 0;
892 
893                 start_reply(c, SUCCESS, "text/gemini");
894 		return;
895 
896 	default:
897 		/* unreachable */
898 		abort();
899 	}
900 
901 	close(dirfd);
902 }
903 
904 static void
905 redirect_canonical_dir(struct client *c)
906 {
907 	size_t len;
908 
909 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
910 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
911 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
912 
913 	if (len >= sizeof(c->sbuf)) {
914 		start_reply(c, TEMP_FAILURE, "internal server error");
915 		return;
916 	}
917 
918 	start_reply(c, TEMP_REDIRECT, c->sbuf);
919 }
920 
921 static void
922 enter_handle_dirlist(int fd, short ev, void *d)
923 {
924 	struct client *c = d;
925 	char b[PATH_MAX];
926 	size_t l;
927 
928 	strlcpy(b, c->iri.path, sizeof(b));
929 	l = snprintf(c->sbuf, sizeof(c->sbuf),
930 	    "# Index of %s\n\n", b);
931 	if (l >= sizeof(c->sbuf)) {
932 		/*
933 		 * This is impossible, given that we have enough space
934 		 * in c->sbuf to hold the ancilliary string plus the
935 		 * full path; but it wouldn't read nice without some
936 		 * error checking, and I'd like to avoid a strlen.
937 		 */
938 		close_conn(fd, ev, c);
939 		return;
940 	}
941 
942 	c->len = l;
943 	handle_dirlist(fd, ev, c);
944 }
945 
946 static void
947 handle_dirlist(int fd, short ev, void *d)
948 {
949 	struct client *c = d;
950 	ssize_t r;
951 
952 	while (c->len > 0) {
953 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
954 		case -1:
955 			close_conn(fd, ev, c);
956 			return;
957 		case TLS_WANT_POLLOUT:
958 			yield_read(fd, c, &handle_dirlist);
959 			return;
960 		case TLS_WANT_POLLIN:
961 			yield_write(fd, c, &handle_dirlist);
962 			return;
963 		default:
964 			c->off += r;
965 			c->len -= r;
966 		}
967 	}
968 
969 	send_directory_listing(fd, ev, c);
970 }
971 
972 static int
973 read_next_dir_entry(struct client *c)
974 {
975 	if (c->diroff == c->dirlen)
976 		return 0;
977 
978 	/* XXX: url escape */
979 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s\n",
980 	    c->dir[c->diroff]->d_name);
981 
982 	free(c->dir[c->diroff]);
983 	c->diroff++;
984 
985 	c->len = strlen(c->sbuf);
986 	c->off = 0;
987 	return 1;
988 }
989 
990 static void
991 send_directory_listing(int fd, short ev, void *d)
992 {
993 	struct client *c = d;
994 	ssize_t r;
995 
996 	while (1) {
997 		if (c->len == 0) {
998 			if (!read_next_dir_entry(c))
999 				goto end;
1000 		}
1001 
1002 		while (c->len > 0) {
1003 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
1004 			case -1:
1005 				goto end;
1006 
1007 			case TLS_WANT_POLLOUT:
1008 				yield_read(fd, c, &send_directory_listing);
1009 				return;
1010 
1011 			case TLS_WANT_POLLIN:
1012 				yield_write(fd, c, &send_directory_listing);
1013 				return;
1014 
1015 			default:
1016 				c->off += r;
1017 				c->len -= r;
1018 				break;
1019 			}
1020 		}
1021 	}
1022 
1023 end:
1024 	close_conn(fd, ev, d);
1025 }
1026 
1027 /* accumulate the meta line from the cgi script. */
1028 static void
1029 handle_cgi_reply(int fd, short ev, void *d)
1030 {
1031 	struct client *c = d;
1032 	void	*buf, *e;
1033 	size_t	 len;
1034 	ssize_t	 r;
1035 
1036 
1037 	buf = c->sbuf + c->len;
1038 	len = sizeof(c->sbuf) - c->len;
1039 
1040 	r = read(c->pfd, buf, len);
1041 	if (r == 0 || r == -1) {
1042 		start_reply(c, CGI_ERROR, "CGI error");
1043 		return;
1044 	}
1045 
1046 	c->len += r;
1047 
1048 	/* TODO: error if the CGI script don't reply correctly */
1049 	e = strchr(c->sbuf, '\n');
1050 	if (e != NULL || c->len == sizeof(c->sbuf)) {
1051 		log_request(c, c->sbuf, c->len);
1052 
1053 		c->off = 0;
1054 		handle_copy(fd, ev, c);
1055 		return;
1056 	}
1057 
1058 	yield_read(fd, c, &handle_cgi_reply);
1059 }
1060 
1061 static void
1062 handle_copy(int fd, short ev, void *d)
1063 {
1064 	struct client *c = d;
1065 	ssize_t r;
1066 
1067 	while (1) {
1068 		while (c->len > 0) {
1069 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
1070 			case -1:
1071 				goto end;
1072 
1073 			case TLS_WANT_POLLOUT:
1074 				yield_write(c->fd, c, &handle_copy);
1075 				return;
1076 
1077 			case TLS_WANT_POLLIN:
1078 				yield_read(c->fd, c, &handle_copy);
1079 				return;
1080 
1081 			default:
1082                                 c->off += r;
1083 				c->len -= r;
1084 				break;
1085 			}
1086 		}
1087 
1088 		switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
1089 		case 0:
1090 			goto end;
1091 		case -1:
1092 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
1093 				yield_read(c->pfd, c, &handle_copy);
1094 				return;
1095 			}
1096 			goto end;
1097 		default:
1098 			c->len = r;
1099 			c->off = 0;
1100 		}
1101 	}
1102 
1103 end:
1104 	close_conn(c->fd, ev, d);
1105 }
1106 
1107 void
1108 close_conn(int fd, short ev, void *d)
1109 {
1110 	struct client	*c = d;
1111 	struct mbuf	*mbuf;
1112 
1113 	switch (tls_close(c->ctx)) {
1114 	case TLS_WANT_POLLIN:
1115 		yield_read(c->fd, c, &close_conn);
1116 		return;
1117 	case TLS_WANT_POLLOUT:
1118 		yield_read(c->fd, c, &close_conn);
1119 		return;
1120 	}
1121 
1122 	connected_clients--;
1123 
1124 	while ((mbuf = TAILQ_FIRST(&c->mbufhead)) != NULL) {
1125 		TAILQ_REMOVE(&c->mbufhead, mbuf, mbufs);
1126 		free(mbuf);
1127 	}
1128 
1129 	tls_free(c->ctx);
1130 	c->ctx = NULL;
1131 
1132 	if (c->pfd != -1)
1133 		close(c->pfd);
1134 
1135 	if (c->dir != NULL)
1136 		free(c->dir);
1137 
1138 	close(c->fd);
1139 	c->fd = -1;
1140 }
1141 
1142 static void
1143 do_accept(int sock, short et, void *d)
1144 {
1145 	struct client *c;
1146 	struct sockaddr_storage addr;
1147 	struct sockaddr *saddr;
1148 	socklen_t len;
1149 	int i, fd;
1150 
1151 	(void)et;
1152 
1153 	saddr = (struct sockaddr*)&addr;
1154 	len = sizeof(addr);
1155 	if ((fd = accept(sock, saddr, &len)) == -1) {
1156 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1157 			return;
1158 		fatal("accept: %s", strerror(errno));
1159 	}
1160 
1161 	mark_nonblock(fd);
1162 
1163 	for (i = 0; i < MAX_USERS; ++i) {
1164 		c = &clients[i];
1165 		if (c->fd == -1) {
1166 			memset(c, 0, sizeof(*c));
1167 			c->id = i;
1168 			if (tls_accept_socket(ctx, &c->ctx, fd) == -1)
1169 				break; /* goodbye fd! */
1170 
1171 			c->fd = fd;
1172 			c->pfd = -1;
1173 			c->dir = NULL;
1174 			c->addr = addr;
1175 			c->fcgi = -1;
1176 
1177 			yield_read(fd, c, &handle_handshake);
1178 			connected_clients++;
1179 			return;
1180 		}
1181 	}
1182 
1183 	close(fd);
1184 }
1185 
1186 static struct client *
1187 client_by_id(int id)
1188 {
1189 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1190 		fatal("in client_by_id: invalid id %d", id);
1191 	return &clients[id];
1192 }
1193 
1194 struct client *
1195 try_client_by_id(int id)
1196 {
1197 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1198                 return NULL;
1199 	return &clients[id];
1200 }
1201 
1202 static void
1203 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1204 {
1205 	struct client *c;
1206 
1207 	c = client_by_id(imsg->hdr.peerid);
1208 
1209 	if ((c->pfd = imsg->fd) == -1)
1210 		start_reply(c, TEMP_FAILURE, "internal server error");
1211 	else
1212 		yield_read(c->pfd, c, &handle_cgi_reply);
1213 }
1214 
1215 static void
1216 handle_imsg_fcgi_fd(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1217 {
1218 	struct client	*c;
1219 	struct fcgi	*f;
1220 	int		 i, id;
1221 
1222 	id = imsg->hdr.peerid;
1223 	f = &fcgi[id];
1224 
1225 	if ((f->fd = imsg->fd) != -1) {
1226 		f->s = FCGI_READY;
1227 		event_set(&f->e, imsg->fd, EV_READ | EV_PERSIST, &handle_fcgi,
1228 		    &fcgi[id]);
1229 		event_add(&f->e, NULL);
1230 	} else {
1231 		f->s = FCGI_OFF;
1232 	}
1233 
1234 	for (i = 0; i < MAX_USERS; ++i) {
1235 		c = &clients[i];
1236 		if (c->fd == -1)
1237 			continue;
1238 		if (c->fcgi != id)
1239 			continue;
1240 
1241 		if (f->fd == -1) {
1242 			c->fcgi = -1;
1243 			start_reply(c, TEMP_FAILURE, "internal server error");
1244 		} else
1245 			send_fcgi_req(f, c);
1246 	}
1247 }
1248 
1249 static void
1250 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1251 {
1252 	size_t i;
1253 
1254 	(void)imsg;
1255 	(void)len;
1256 
1257 	/*
1258 	 * don't call event_loopbreak since we want to finish to
1259 	 * handle the ongoing connections.
1260 	 */
1261 
1262 	shutting_down = 1;
1263 
1264 	event_del(&e4);
1265 	if (has_ipv6)
1266 		event_del(&e6);
1267 	if (has_siginfo)
1268 		signal_del(&siginfo);
1269 	event_del(&imsgev);
1270 	signal_del(&sigusr2);
1271 
1272 	for (i = 0; i < FCGI_MAX; ++i) {
1273 		if (fcgi[i].path == NULL && fcgi[i].prog == NULL)
1274 			break;
1275 
1276 		if (!event_pending(&fcgi[i].e, EV_READ, NULL) ||
1277 		    fcgi[i].pending != 0)
1278 			continue;
1279 
1280 		fcgi_close_backend(&fcgi[i]);
1281 	}
1282 }
1283 
1284 static void
1285 handle_dispatch_imsg(int fd, short ev, void *d)
1286 {
1287 	struct imsgbuf *ibuf = d;
1288 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1289 }
1290 
1291 static void
1292 handle_siginfo(int fd, short ev, void *d)
1293 {
1294 	(void)fd;
1295 	(void)ev;
1296 	(void)d;
1297 
1298 	log_info(NULL, "%d connected clients", connected_clients);
1299 }
1300 
1301 void
1302 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1303 {
1304 	size_t i;
1305 
1306 	ctx = ctx_;
1307 
1308 	event_init();
1309 
1310 	memset(&clients, 0, sizeof(clients));
1311 	for (i = 0; i < MAX_USERS; ++i)
1312 		clients[i].fd = -1;
1313 
1314 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1315 	event_add(&e4, NULL);
1316 
1317 	if (sock6 != -1) {
1318 		has_ipv6 = 1;
1319 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1320 		event_add(&e6, NULL);
1321 	}
1322 
1323 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1324 	event_add(&imsgev, NULL);
1325 
1326 #ifdef SIGINFO
1327 	has_siginfo = 1;
1328 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1329 	signal_add(&siginfo, NULL);
1330 #endif
1331 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1332 	signal_add(&sigusr2, NULL);
1333 
1334 	sandbox_server_process();
1335 	event_dispatch();
1336 	_exit(0);
1337 }