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