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 != '/' && end > path)
410 			end--;
411 
412 		if (end == path)
413 			break;
414 
415 		*end = '\0';
416 
417 		switch (check_path(c, path, &c->pfd)) {
418 		case FILE_EXECUTABLE:
419 			start_cgi(path, end+1, c);
420 			return;
421 		case FILE_MISSING:
422 			break;
423 		default:
424 			goto err;
425 		}
426 
427 		*end = '/';
428 		end--;
429 	}
430 
431 err:
432 	start_reply(c, NOT_FOUND, "not found");
433 	return;
434 }
435 
436 void
437 mark_nonblock(int fd)
438 {
439 	int flags;
440 
441 	if ((flags = fcntl(fd, F_GETFL)) == -1)
442 		fatal("fcntl(F_GETFL): %s", strerror(errno));
443 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
444 		fatal("fcntl(F_SETFL): %s", strerror(errno));
445 }
446 
447 static void
448 handle_handshake(int fd, short ev, void *d)
449 {
450 	struct client *c = d;
451 	struct vhost *h;
452 	struct alist *a;
453 	const char *servname;
454 	const char *parse_err = "unknown error";
455 
456 	switch (tls_handshake(c->ctx)) {
457 	case 0:  /* success */
458 	case -1: /* already handshaked */
459 		break;
460 	case TLS_WANT_POLLIN:
461 		yield_read(fd, c, &handle_handshake);
462 		return;
463 	case TLS_WANT_POLLOUT:
464 		yield_write(fd, c, &handle_handshake);
465 		return;
466 	default:
467 		/* unreachable */
468 		abort();
469 	}
470 
471 	if ((servname = tls_conn_servername(c->ctx)) == NULL) {
472 		log_debug(c, "handshake: missing SNI");
473 		goto err;
474 	}
475 
476 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
477 		log_info(c, "puny_decode: %s", parse_err);
478 		goto err;
479 	}
480 
481 	TAILQ_FOREACH(h, &hosts, vhosts) {
482 		if (matches(h->domain, c->domain))
483 			goto found;
484 		TAILQ_FOREACH(a, &h->aliases, aliases) {
485 			if (matches(a->alias, c->domain))
486 				goto found;
487 		}
488 	}
489 
490 found:
491 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
492 	    servname != NULL ? servname : "(null)",
493 	    c->domain,
494 	    h != NULL ? h->domain : "(null)");
495 
496 	if (h != NULL) {
497 		c->host = h;
498 		handle_open_conn(fd, ev, c);
499 		return;
500 	}
501 
502 err:
503 	if (servname != NULL)
504 		strlcpy(c->req, servname, sizeof(c->req));
505 	else
506 		strlcpy(c->req, "null", sizeof(c->req));
507 
508 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
509 }
510 
511 static const char *
512 strip_path(const char *path, int strip)
513 {
514 	char *t;
515 
516 	while (strip > 0) {
517 		if ((t = strchr(path, '/')) == NULL) {
518 			path = strchr(path, '\0');
519 			break;
520 		}
521 		path = t;
522 		strip--;
523 	}
524 
525 	return path;
526 }
527 
528 static void
529 fmt_sbuf(const char *fmt, struct client *c, const char *path)
530 {
531 	size_t i;
532         char buf[32];
533 
534 	memset(buf, 0, sizeof(buf));
535 	for (i = 0; *fmt; ++fmt) {
536 		if (i == sizeof(buf)-1 || *fmt == '%') {
537 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
538 			memset(buf, 0, sizeof(buf));
539 			i = 0;
540 		}
541 
542 		if (*fmt != '%') {
543 			buf[i++] = *fmt;
544 			continue;
545 		}
546 
547 		switch (*++fmt) {
548 		case '%':
549 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
550 			break;
551 		case 'p':
552 			if (*path != '/')
553 				strlcat(c->sbuf, "/", sizeof(c->sbuf));
554 			strlcat(c->sbuf, path, sizeof(c->sbuf));
555 			break;
556 		case 'q':
557 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
558 			break;
559 		case 'P':
560 			snprintf(buf, sizeof(buf), "%d", conf.port);
561 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
562 			memset(buf, 0, sizeof(buf));
563 			break;
564 		case 'N':
565 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
566 			break;
567 		default:
568 			fatal("%s: unknown fmt specifier %c",
569 			    __func__, *fmt);
570 		}
571 	}
572 
573 	if (i != 0)
574 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
575 }
576 
577 /* 1 if a matching `block return' (and apply it), 0 otherwise */
578 static int
579 apply_block_return(struct client *c)
580 {
581 	const char *fmt, *path;
582 	int code;
583 
584 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
585 		return 0;
586 
587 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
588 	fmt_sbuf(fmt, c, path);
589 
590 	start_reply(c, code, c->sbuf);
591 	return 1;
592 }
593 
594 /* 1 if matching `fcgi' (and apply it), 0 otherwise */
595 static int
596 apply_fastcgi(struct client *c)
597 {
598 	int		 id;
599 	struct fcgi	*f;
600 
601 	if ((id = vhost_fastcgi(c->host, c->iri.path)) == -1)
602 		return 0;
603 
604 	switch ((f = &fcgi[id])->s) {
605 	case FCGI_OFF:
606 		f->s = FCGI_INFLIGHT;
607 		log_info(c, "opening fastcgi connection for (%s,%s,%s)",
608 		    f->path, f->port, f->prog);
609 		imsg_compose(&exibuf, IMSG_FCGI_REQ, 0, 0, -1,
610 		    &id, sizeof(id));
611 		imsg_flush(&exibuf);
612                 /* fallthrough */
613 	case FCGI_INFLIGHT:
614                 c->fcgi = id;
615 		break;
616 	case FCGI_READY:
617                 c->fcgi = id;
618 		fcgi_req(f, c);
619 		break;
620 	}
621 
622 	return 1;
623 }
624 
625 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
626 static int
627 apply_require_ca(struct client *c)
628 {
629 	X509_STORE	*store;
630 	const uint8_t	*cert;
631 	size_t		 len;
632 
633 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
634 		return 0;
635 
636 	if (!tls_peer_cert_provided(c->ctx)) {
637 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
638 		return 1;
639 	}
640 
641 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
642 	if (!validate_against_ca(store, cert, len)) {
643 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
644 		return 1;
645 	}
646 
647 	return 0;
648 }
649 
650 static void
651 handle_open_conn(int fd, short ev, void *d)
652 {
653 	struct client *c = d;
654 	const char *parse_err = "invalid request";
655 	char decoded[DOMAIN_NAME_LEN];
656 
657 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
658 	case -1:
659 		log_err(c, "tls_read: %s", tls_error(c->ctx));
660 		close_conn(fd, ev, c);
661 		return;
662 
663 	case TLS_WANT_POLLIN:
664 		yield_read(fd, c, &handle_open_conn);
665 		return;
666 
667 	case TLS_WANT_POLLOUT:
668 		yield_write(fd, c, &handle_open_conn);
669 		return;
670 	}
671 
672 	if (!trim_req_iri(c->req, &parse_err) ||
673 	    !parse_iri(c->req, &c->iri, &parse_err) ||
674 	    !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
675 		log_info(c, "iri parse error: %s", parse_err);
676 		start_reply(c, BAD_REQUEST, "invalid request");
677 		return;
678 	}
679 
680 	if (c->iri.port_no != conf.port ||
681 	    strcmp(c->iri.schema, "gemini") ||
682 	    strcmp(decoded, c->domain)) {
683 		start_reply(c, PROXY_REFUSED, "won't proxy request");
684 		return;
685 	}
686 
687 	if (apply_require_ca(c))
688 		return;
689 
690 	if (apply_block_return(c))
691 		return;
692 
693 	if (apply_fastcgi(c))
694 		return;
695 
696 	if (c->host->entrypoint != NULL) {
697 		c->loc = 0;
698 		start_cgi(c->host->entrypoint, c->iri.path, c);
699 		return;
700 	}
701 
702 	open_file(c);
703 }
704 
705 void
706 start_reply(struct client *c, int code, const char *meta)
707 {
708 	c->code = code;
709 	c->meta = meta;
710 	handle_start_reply(c->fd, 0, c);
711 }
712 
713 static void
714 handle_start_reply(int fd, short ev, void *d)
715 {
716 	struct client *c = d;
717 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
718 	const char *lang;
719 	size_t len;
720 
721 	lang = vhost_lang(c->host, c->iri.path);
722 
723 	snprintf(buf, sizeof(buf), "%d ", c->code);
724 	strlcat(buf, c->meta, sizeof(buf));
725 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
726 		strlcat(buf, "; lang=", sizeof(buf));
727 		strlcat(buf, lang, sizeof(buf));
728 	}
729 
730 	len = strlcat(buf, "\r\n", sizeof(buf));
731 	assert(len < sizeof(buf));
732 
733 	switch (tls_write(c->ctx, buf, len)) {
734 	case -1:
735 		close_conn(fd, ev, c);
736 		return;
737 	case TLS_WANT_POLLIN:
738 		yield_read(fd, c, &handle_start_reply);
739 		return;
740 	case TLS_WANT_POLLOUT:
741 		yield_write(fd, c, &handle_start_reply);
742 		return;
743 	}
744 
745 	if (!vhost_disable_log(c->host, c->iri.path))
746 		log_request(c, buf, sizeof(buf));
747 
748 	if (c->code != SUCCESS)
749 		close_conn(fd, ev, c);
750 	else
751 		c->next(fd, ev, c);
752 }
753 
754 static size_t
755 host_nth(struct vhost *h)
756 {
757 	struct vhost	*v;
758 	size_t		 i = 0;
759 
760 	TAILQ_FOREACH(v, &hosts, vhosts) {
761 		if (v == h)
762 			return i;
763 		i++;
764 	}
765 
766 	abort();
767 }
768 
769 static void
770 start_cgi(const char *spath, const char *relpath, struct client *c)
771 {
772 	char addr[NI_MAXHOST];
773 	const char *t;
774 	struct cgireq req;
775 	int e;
776 
777 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
778 	    addr, sizeof(addr),
779 	    NULL, 0,
780 	    NI_NUMERICHOST);
781 	if (e != 0)
782 		fatal("getnameinfo failed");
783 
784 	memset(&req, 0, sizeof(req));
785 
786 	memcpy(req.buf, c->req, sizeof(req.buf));
787 
788 	req.iri_schema_off = c->iri.schema - c->req;
789 	req.iri_host_off = c->iri.host - c->req;
790 	req.iri_port_off = c->iri.port - c->req;
791 	req.iri_path_off = c->iri.path - c->req;
792 	req.iri_query_off = c->iri.query - c->req;
793 	req.iri_fragment_off = c->iri.fragment - c->req;
794 
795 	req.iri_portno = c->iri.port_no;
796 
797 	strlcpy(req.spath, spath, sizeof(req.spath));
798 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
799 	strlcpy(req.addr, addr, sizeof(req.addr));
800 
801 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
802 		strlcpy(req.subject, t, sizeof(req.subject));
803 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
804 		strlcpy(req.issuer, t, sizeof(req.issuer));
805 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
806 		strlcpy(req.hash, t, sizeof(req.hash));
807 	if ((t = tls_conn_version(c->ctx)) != NULL)
808 		strlcpy(req.version, t, sizeof(req.version));
809 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
810 		strlcpy(req.cipher, t, sizeof(req.cipher));
811 
812 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
813 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
814 	req.notafter = tls_peer_cert_notafter(c->ctx);
815 
816 	req.host_off = host_nth(c->host);
817 	req.loc_off = c->loc;
818 
819 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
820 	imsg_flush(&exibuf);
821 
822 	close(c->pfd);
823 }
824 
825 static void
826 open_dir(struct client *c)
827 {
828 	size_t len;
829 	int dirfd, root;
830 	char *before_file;
831 
832 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
833 
834 	len = strlen(c->iri.path);
835 	if (len > 0 && !ends_with(c->iri.path, "/")) {
836 		redirect_canonical_dir(c);
837 		return;
838 	}
839 
840 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
841 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
842 	if (!ends_with(c->sbuf, "/"))
843 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
844 	before_file = strchr(c->sbuf, '\0');
845 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
846 	    sizeof(c->sbuf));
847 	if (len >= sizeof(c->sbuf)) {
848 		start_reply(c, TEMP_FAILURE, "internal server error");
849 		return;
850 	}
851 
852 	c->iri.path = c->sbuf;
853 
854 	/* close later unless we have to generate the dir listing */
855 	dirfd = c->pfd;
856 	c->pfd = -1;
857 
858 	switch (check_path(c, c->iri.path, &c->pfd)) {
859 	case FILE_EXECUTABLE:
860 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
861 			start_cgi(c->iri.path, "", c);
862 			break;
863 		}
864 
865 		/* fallthrough */
866 
867 	case FILE_EXISTS:
868 		c->next = handle_copy;
869 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
870 		break;
871 
872 	case FILE_DIRECTORY:
873 		start_reply(c, TEMP_REDIRECT, c->sbuf);
874 		break;
875 
876 	case FILE_MISSING:
877 		*before_file = '\0';
878 
879 		if (!vhost_auto_index(c->host, c->iri.path)) {
880 			start_reply(c, NOT_FOUND, "not found");
881 			break;
882 		}
883 
884 		c->next = enter_handle_dirlist;
885 
886 		c->dirlen = scandir_fd(dirfd, &c->dir,
887 		    root ? select_non_dotdot : select_non_dot,
888 		    alphasort);
889 		if (c->dirlen == -1) {
890 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
891 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
892 			start_reply(c, TEMP_FAILURE, "internal server error");
893 			return;
894 		}
895 		c->diroff = 0;
896 		c->off = 0;
897 
898                 start_reply(c, SUCCESS, "text/gemini");
899 		return;
900 
901 	default:
902 		/* unreachable */
903 		abort();
904 	}
905 
906 	close(dirfd);
907 }
908 
909 static void
910 redirect_canonical_dir(struct client *c)
911 {
912 	size_t len;
913 
914 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
915 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
916 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
917 
918 	if (len >= sizeof(c->sbuf)) {
919 		start_reply(c, TEMP_FAILURE, "internal server error");
920 		return;
921 	}
922 
923 	start_reply(c, TEMP_REDIRECT, c->sbuf);
924 }
925 
926 static void
927 enter_handle_dirlist(int fd, short ev, void *d)
928 {
929 	struct client *c = d;
930 	char b[PATH_MAX];
931 	size_t l;
932 
933 	strlcpy(b, c->iri.path, sizeof(b));
934 	l = snprintf(c->sbuf, sizeof(c->sbuf),
935 	    "# Index of %s\n\n", b);
936 	if (l >= sizeof(c->sbuf)) {
937 		/*
938 		 * This is impossible, given that we have enough space
939 		 * in c->sbuf to hold the ancilliary string plus the
940 		 * full path; but it wouldn't read nice without some
941 		 * error checking, and I'd like to avoid a strlen.
942 		 */
943 		close_conn(fd, ev, c);
944 		return;
945 	}
946 
947 	c->len = l;
948 	handle_dirlist(fd, ev, c);
949 }
950 
951 static void
952 handle_dirlist(int fd, short ev, void *d)
953 {
954 	struct client *c = d;
955 	ssize_t r;
956 
957 	while (c->len > 0) {
958 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
959 		case -1:
960 			close_conn(fd, ev, c);
961 			return;
962 		case TLS_WANT_POLLOUT:
963 			yield_read(fd, c, &handle_dirlist);
964 			return;
965 		case TLS_WANT_POLLIN:
966 			yield_write(fd, c, &handle_dirlist);
967 			return;
968 		default:
969 			c->off += r;
970 			c->len -= r;
971 		}
972 	}
973 
974 	send_directory_listing(fd, ev, c);
975 }
976 
977 static int
978 read_next_dir_entry(struct client *c)
979 {
980 	if (c->diroff == c->dirlen)
981 		return 0;
982 
983 	/* XXX: url escape */
984 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s\n",
985 	    c->dir[c->diroff]->d_name);
986 
987 	free(c->dir[c->diroff]);
988 	c->diroff++;
989 
990 	c->len = strlen(c->sbuf);
991 	c->off = 0;
992 	return 1;
993 }
994 
995 static void
996 send_directory_listing(int fd, short ev, void *d)
997 {
998 	struct client *c = d;
999 	ssize_t r;
1000 
1001 	while (1) {
1002 		if (c->len == 0) {
1003 			if (!read_next_dir_entry(c))
1004 				goto end;
1005 		}
1006 
1007 		while (c->len > 0) {
1008 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
1009 			case -1:
1010 				goto end;
1011 
1012 			case TLS_WANT_POLLOUT:
1013 				yield_read(fd, c, &send_directory_listing);
1014 				return;
1015 
1016 			case TLS_WANT_POLLIN:
1017 				yield_write(fd, c, &send_directory_listing);
1018 				return;
1019 
1020 			default:
1021 				c->off += r;
1022 				c->len -= r;
1023 				break;
1024 			}
1025 		}
1026 	}
1027 
1028 end:
1029 	close_conn(fd, ev, d);
1030 }
1031 
1032 /* accumulate the meta line from the cgi script. */
1033 static void
1034 handle_cgi_reply(int fd, short ev, void *d)
1035 {
1036 	struct client *c = d;
1037 	void	*buf, *e;
1038 	size_t	 len;
1039 	ssize_t	 r;
1040 
1041 
1042 	buf = c->sbuf + c->len;
1043 	len = sizeof(c->sbuf) - c->len;
1044 
1045 	r = read(c->pfd, buf, len);
1046 	if (r == 0 || r == -1) {
1047 		start_reply(c, CGI_ERROR, "CGI error");
1048 		return;
1049 	}
1050 
1051 	c->len += r;
1052 
1053 	/* TODO: error if the CGI script don't reply correctly */
1054 	e = strchr(c->sbuf, '\n');
1055 	if (e != NULL || c->len == sizeof(c->sbuf)) {
1056 		log_request(c, c->sbuf, c->len);
1057 
1058 		c->off = 0;
1059 		handle_copy(fd, ev, c);
1060 		return;
1061 	}
1062 
1063 	yield_read(fd, c, &handle_cgi_reply);
1064 }
1065 
1066 static void
1067 handle_copy(int fd, short ev, void *d)
1068 {
1069 	struct client *c = d;
1070 	ssize_t r;
1071 
1072 	while (1) {
1073 		while (c->len > 0) {
1074 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
1075 			case -1:
1076 				goto end;
1077 
1078 			case TLS_WANT_POLLOUT:
1079 				yield_write(c->fd, c, &handle_copy);
1080 				return;
1081 
1082 			case TLS_WANT_POLLIN:
1083 				yield_read(c->fd, c, &handle_copy);
1084 				return;
1085 
1086 			default:
1087                                 c->off += r;
1088 				c->len -= r;
1089 				break;
1090 			}
1091 		}
1092 
1093 		switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
1094 		case 0:
1095 			goto end;
1096 		case -1:
1097 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
1098 				yield_read(c->pfd, c, &handle_copy);
1099 				return;
1100 			}
1101 			goto end;
1102 		default:
1103 			c->len = r;
1104 			c->off = 0;
1105 		}
1106 	}
1107 
1108 end:
1109 	close_conn(c->fd, ev, d);
1110 }
1111 
1112 void
1113 close_conn(int fd, short ev, void *d)
1114 {
1115 	struct client	*c = d;
1116 	struct mbuf	*mbuf;
1117 
1118 	switch (tls_close(c->ctx)) {
1119 	case TLS_WANT_POLLIN:
1120 		yield_read(c->fd, c, &close_conn);
1121 		return;
1122 	case TLS_WANT_POLLOUT:
1123 		yield_read(c->fd, c, &close_conn);
1124 		return;
1125 	}
1126 
1127 	connected_clients--;
1128 
1129 	while ((mbuf = TAILQ_FIRST(&c->mbufhead)) != NULL) {
1130 		TAILQ_REMOVE(&c->mbufhead, mbuf, mbufs);
1131 		free(mbuf);
1132 	}
1133 
1134 	tls_free(c->ctx);
1135 	c->ctx = NULL;
1136 
1137 	if (c->pfd != -1)
1138 		close(c->pfd);
1139 
1140 	if (c->dir != NULL)
1141 		free(c->dir);
1142 
1143 	close(c->fd);
1144 	c->fd = -1;
1145 }
1146 
1147 static void
1148 do_accept(int sock, short et, void *d)
1149 {
1150 	struct client *c;
1151 	struct sockaddr_storage addr;
1152 	struct sockaddr *saddr;
1153 	socklen_t len;
1154 	int i, fd;
1155 
1156 	(void)et;
1157 
1158 	saddr = (struct sockaddr*)&addr;
1159 	len = sizeof(addr);
1160 	if ((fd = accept(sock, saddr, &len)) == -1) {
1161 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1162 			return;
1163 		fatal("accept: %s", strerror(errno));
1164 	}
1165 
1166 	mark_nonblock(fd);
1167 
1168 	for (i = 0; i < MAX_USERS; ++i) {
1169 		c = &clients[i];
1170 		if (c->fd == -1) {
1171 			memset(c, 0, sizeof(*c));
1172 			c->id = i;
1173 			if (tls_accept_socket(ctx, &c->ctx, fd) == -1)
1174 				break; /* goodbye fd! */
1175 
1176 			c->fd = fd;
1177 			c->pfd = -1;
1178 			c->dir = NULL;
1179 			c->addr = addr;
1180 			c->fcgi = -1;
1181 
1182 			TAILQ_INIT(&c->mbufhead);
1183 
1184 			yield_read(fd, c, &handle_handshake);
1185 			connected_clients++;
1186 			return;
1187 		}
1188 	}
1189 
1190 	close(fd);
1191 }
1192 
1193 static struct client *
1194 client_by_id(int id)
1195 {
1196 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1197 		fatal("in client_by_id: invalid id %d", id);
1198 	return &clients[id];
1199 }
1200 
1201 struct client *
1202 try_client_by_id(int id)
1203 {
1204 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1205                 return NULL;
1206 	return &clients[id];
1207 }
1208 
1209 static void
1210 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1211 {
1212 	struct client *c;
1213 
1214 	c = client_by_id(imsg->hdr.peerid);
1215 
1216 	if ((c->pfd = imsg->fd) == -1)
1217 		start_reply(c, TEMP_FAILURE, "internal server error");
1218 	else
1219 		yield_read(c->pfd, c, &handle_cgi_reply);
1220 }
1221 
1222 static void
1223 handle_imsg_fcgi_fd(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1224 {
1225 	struct client	*c;
1226 	struct fcgi	*f;
1227 	int		 i, id;
1228 
1229 	id = imsg->hdr.peerid;
1230 	f = &fcgi[id];
1231 
1232 	if ((f->fd = imsg->fd) == -1)
1233 		f->s = FCGI_OFF;
1234 	else {
1235 		mark_nonblock(f->fd);
1236 
1237 		f->s = FCGI_READY;
1238 
1239 		f->bev = bufferevent_new(f->fd, fcgi_read, fcgi_write,
1240 		    fcgi_error, f);
1241 		if (f->bev == NULL) {
1242 			close(f->fd);
1243 			log_err(NULL, "%s: failed to allocate client buffer",
1244 			    __func__);
1245 			f->s = FCGI_OFF;
1246 		}
1247 
1248 		bufferevent_enable(f->bev, EV_READ|EV_WRITE);
1249 	}
1250 
1251 	for (i = 0; i < MAX_USERS; ++i) {
1252 		c = &clients[i];
1253 		if (c->fd == -1)
1254 			continue;
1255 		if (c->fcgi != id)
1256 			continue;
1257 
1258 		if (f->s == FCGI_OFF) {
1259 			c->fcgi = -1;
1260 			start_reply(c, TEMP_FAILURE, "internal server error");
1261 		} else
1262 			fcgi_req(f, c);
1263 	}
1264 }
1265 
1266 static void
1267 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1268 {
1269 	size_t i;
1270 
1271 	(void)imsg;
1272 	(void)len;
1273 
1274 	/*
1275 	 * don't call event_loopbreak since we want to finish to
1276 	 * handle the ongoing connections.
1277 	 */
1278 
1279 	shutting_down = 1;
1280 
1281 	event_del(&e4);
1282 	if (has_ipv6)
1283 		event_del(&e6);
1284 	if (has_siginfo)
1285 		signal_del(&siginfo);
1286 	event_del(&imsgev);
1287 	signal_del(&sigusr2);
1288 
1289 	for (i = 0; i < FCGI_MAX; ++i) {
1290 		if (fcgi[i].path == NULL && fcgi[i].prog == NULL)
1291 			break;
1292 
1293 		if (fcgi[i].bev == NULL || fcgi[i].pending != 0)
1294 			continue;
1295 
1296 		fcgi_close_backend(&fcgi[i]);
1297 	}
1298 }
1299 
1300 static void
1301 handle_dispatch_imsg(int fd, short ev, void *d)
1302 {
1303 	struct imsgbuf *ibuf = d;
1304 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1305 }
1306 
1307 static void
1308 handle_siginfo(int fd, short ev, void *d)
1309 {
1310 	(void)fd;
1311 	(void)ev;
1312 	(void)d;
1313 
1314 	log_info(NULL, "%d connected clients", connected_clients);
1315 }
1316 
1317 void
1318 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1319 {
1320 	size_t i;
1321 
1322 	ctx = ctx_;
1323 
1324 	event_init();
1325 
1326 	memset(&clients, 0, sizeof(clients));
1327 	for (i = 0; i < MAX_USERS; ++i)
1328 		clients[i].fd = -1;
1329 
1330 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1331 	event_add(&e4, NULL);
1332 
1333 	if (sock6 != -1) {
1334 		has_ipv6 = 1;
1335 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1336 		event_add(&e6, NULL);
1337 	}
1338 
1339 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1340 	event_add(&imsgev, NULL);
1341 
1342 #ifdef SIGINFO
1343 	has_siginfo = 1;
1344 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1345 	signal_add(&siginfo, NULL);
1346 #endif
1347 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1348 	signal_add(&sigusr2, NULL);
1349 
1350 	sandbox_server_process();
1351 	event_dispatch();
1352 	_exit(0);
1353 }