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Date:: Thu Apr 29 18:23:35 2021 UTC
Message:: added ``alias'' option to define hostname aliases for a server
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1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "gmid.h"
18 
19 #include <sys/stat.h>
20 
21 #include <assert.h>
22 #include <errno.h>
23 #include <event.h>
24 #include <fcntl.h>
25 #include <fnmatch.h>
26 #include <limits.h>
27 #include <string.h>
28 
29 static struct client	 clients[MAX_USERS];
30 static struct tls	*ctx;
31 
32 static struct event e4, e6, imsgev, siginfo, sigusr2;
33 static int has_ipv6, has_siginfo;
34 
35 int connected_clients;
36 
37 static inline int matches(const char*, const char*);
38 
39 static inline void yield_read(int, struct client*, statefn);
40 static inline void yield_write(int, struct client*, statefn);
41 
42 static int	 check_path(struct client*, const char*, int*);
43 static void	 open_file(struct client*);
44 static void	 check_for_cgi(struct client*);
45 static void	 handle_handshake(int, short, void*);
46 static char	*strip_path(char*, int);
47 static void	 fmt_sbuf(const char*, struct client*, const char*);
48 static int	 apply_block_return(struct client*);
49 static int	 apply_require_ca(struct client*);
50 static void	 handle_open_conn(int, short, void*);
51 static void	 start_reply(struct client*, int, const char*);
52 static void	 handle_start_reply(int, short, void*);
53 static size_t	 host_nth(struct vhost*);
54 static void	 start_cgi(const char*, const char*, struct client*);
55 static void	 open_dir(struct client*);
56 static void	 redirect_canonical_dir(struct client*);
57 static void	 enter_handle_dirlist(int, short, void*);
58 static void	 handle_dirlist(int, short, void*);
59 static int 	 read_next_dir_entry(struct client*);
60 static void	 send_directory_listing(int, short, void*);
61 static void	 handle_cgi_reply(int, short, void*);
62 static void	 handle_copy(int, short, void*);
63 static void	 close_conn(int, short, void*);
64 static void	 do_accept(int, short, void*);
65 struct client	*client_by_id(int);
66 static void	 handle_imsg_cgi_res(struct imsgbuf*, struct imsg*, size_t);
67 static void	 handle_imsg_quit(struct imsgbuf*, struct imsg*, size_t);
68 static void	 handle_siginfo(int, short, void*);
69 
70 static imsg_handlerfn *handlers[] = {
71 	[IMSG_QUIT] = handle_imsg_quit,
72 	[IMSG_CGI_RES] = handle_imsg_cgi_res,
73 };
74 
75 static inline int
76 matches(const char *pattern, const char *path)
77 {
78 	if (*path == '/')
79 		path++;
80 	return !fnmatch(pattern, path, 0);
81 }
82 
83 static inline void
84 yield_read(int fd, struct client *c, statefn fn)
85 {
86 	event_once(fd, EV_READ, fn, c, NULL);
87 }
88 
89 static inline void
90 yield_write(int fd, struct client *c, statefn fn)
91 {
92 	event_once(fd, EV_WRITE, fn, c, NULL);
93 }
94 
95 const char *
96 vhost_lang(struct vhost *v, const char *path)
97 {
98 	struct location *loc;
99 
100 	if (v == NULL || path == NULL)
101 		return NULL;
102 
103 	loc = TAILQ_FIRST(&v->locations);
104 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
105 		if (loc->lang != NULL) {
106 			if (matches(loc->match, path))
107 				return loc->lang;
108 		}
109 	}
110 
111 	return TAILQ_FIRST(&v->locations)->lang;
112 }
113 
114 const char *
115 vhost_default_mime(struct vhost *v, const char *path)
116 {
117 	struct location *loc;
118 	const char *default_mime = "application/octet-stream";
119 
120 	if (v == NULL || path == NULL)
121 		return default_mime;
122 
123 	loc = TAILQ_FIRST(&v->locations);
124 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
125 		if (loc->default_mime != NULL) {
126 			if (matches(loc->match, path))
127 				return loc->default_mime;
128 		}
129 	}
130 
131 	loc = TAILQ_FIRST(&v->locations);
132 	if (loc->default_mime != NULL)
133 		return loc->default_mime;
134 	return default_mime;
135 }
136 
137 const char *
138 vhost_index(struct vhost *v, const char *path)
139 {
140 	struct location *loc;
141 	const char *index = "index.gmi";
142 
143 	if (v == NULL || path == NULL)
144 		return index;
145 
146 	loc = TAILQ_FIRST(&v->locations);
147 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
148 		if (loc->index != NULL) {
149 			if (matches(loc->match, path))
150 				return loc->index;
151 		}
152 	}
153 
154 	loc = TAILQ_FIRST(&v->locations);
155 	if (loc->index != NULL)
156 		return loc->index;
157 	return index;
158 }
159 
160 int
161 vhost_auto_index(struct vhost *v, const char *path)
162 {
163 	struct location *loc;
164 
165 	if (v == NULL || path == NULL)
166 		return 0;
167 
168 	loc = TAILQ_FIRST(&v->locations);
169 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
170 		if (loc->auto_index != 0) {
171 			if (matches(loc->match, path))
172 				return loc->auto_index == 1;
173 		}
174 	}
175 
176 	loc = TAILQ_FIRST(&v->locations);
177 	return loc->auto_index == 1;
178 }
179 
180 int
181 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
182 {
183 	struct location *loc;
184 
185 	if (v == NULL || path == NULL)
186 		return 0;
187 
188 	loc = TAILQ_FIRST(&v->locations);
189 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
190 		if (loc->block_code != 0) {
191 			if (matches(loc->match, path)) {
192 				*code = loc->block_code;
193 				*fmt = loc->block_fmt;
194 				return 1;
195 			}
196 		}
197 	}
198 
199 	loc = TAILQ_FIRST(&v->locations);
200 	*code = loc->block_code;
201 	*fmt = loc->block_fmt;
202 	return loc->block_code != 0;
203 }
204 
205 int
206 vhost_strip(struct vhost *v, const char *path)
207 {
208 	struct location *loc;
209 
210 	if (v == NULL || path == NULL)
211 		return 0;
212 
213 	loc = TAILQ_FIRST(&v->locations);
214 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
215 		if (loc->strip != 0) {
216 			if (matches(loc->match, path))
217 				return loc->strip;
218 		}
219 	}
220 
221 	loc = TAILQ_FIRST(&v->locations);
222 	return loc->strip;
223 }
224 
225 X509_STORE *
226 vhost_require_ca(struct vhost *v, const char *path)
227 {
228 	struct location *loc;
229 
230 	if (v == NULL || path == NULL)
231 		return NULL;
232 
233 	loc = TAILQ_FIRST(&v->locations);
234 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
235 		if (loc->reqca != NULL) {
236 			if (matches(loc->match, path))
237 				return loc->reqca;
238 		}
239 	}
240 
241 	loc = TAILQ_FIRST(&v->locations);
242 	return loc->reqca;
243 }
244 
245 int
246 vhost_disable_log(struct vhost *v, const char *path)
247 {
248 	struct location *loc;
249 
250 	if (v == NULL || path == NULL)
251 		return 0;
252 
253 	loc = TAILQ_FIRST(&v->locations);
254 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
255 		if (loc->disable_log && matches(loc->match, path))
256 				return 1;
257 	}
258 
259 	loc = TAILQ_FIRST(&v->locations);
260 	return loc->disable_log;
261 }
262 
263 static int
264 check_path(struct client *c, const char *path, int *fd)
265 {
266 	struct stat sb;
267 	const char *p;
268 	int flags;
269 
270 	assert(path != NULL);
271 
272 	if (*path == '\0')
273 		p = ".";
274 	else if (*path == '/')
275 		/* in send_dir we add an initial / (to be
276 		 * redirect-friendly), but here we want to skip it */
277 		p = path+1;
278 	else
279 		p = path;
280 
281 	flags = O_RDONLY | O_NOFOLLOW;
282 
283 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
284 		return FILE_MISSING;
285 
286 	if (fstat(*fd, &sb) == -1) {
287 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
288 		return FILE_MISSING;
289 	}
290 
291 	if (S_ISDIR(sb.st_mode))
292 		return FILE_DIRECTORY;
293 
294 	if (sb.st_mode & S_IXUSR)
295 		return FILE_EXECUTABLE;
296 
297 	return FILE_EXISTS;
298 }
299 
300 static void
301 open_file(struct client *c)
302 {
303 	switch (check_path(c, c->iri.path, &c->pfd)) {
304 	case FILE_EXECUTABLE:
305 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
306 			start_cgi(c->iri.path, "", c);
307 			return;
308 		}
309 
310 		/* fallthrough */
311 
312 	case FILE_EXISTS:
313 		c->next = handle_copy;
314 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
315 		return;
316 
317 	case FILE_DIRECTORY:
318 		open_dir(c);
319 		return;
320 
321 	case FILE_MISSING:
322 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
323 			check_for_cgi(c);
324 			return;
325 		}
326 		start_reply(c, NOT_FOUND, "not found");
327 		return;
328 
329 	default:
330 		/* unreachable */
331 		abort();
332 	}
333 }
334 
335 /*
336  * the inverse of this algorithm, i.e. starting from the start of the
337  * path + strlen(cgi), and checking if each component, should be
338  * faster.  But it's tedious to write.  This does the opposite: starts
339  * from the end and strip one component at a time, until either an
340  * executable is found or we emptied the path.
341  */
342 static void
343 check_for_cgi(struct client *c)
344 {
345 	char path[PATH_MAX];
346 	char *end;
347 
348 	strlcpy(path, c->iri.path, sizeof(path));
349 	end = strchr(path, '\0');
350 
351 	while (end > path) {
352 		/* go up one level.  UNIX paths are simple and POSIX
353 		 * dirname, with its ambiguities on if the given path
354 		 * is changed or not, gives me headaches. */
355 		while (*end != '/')
356 			end--;
357 		*end = '\0';
358 
359 		switch (check_path(c, path, &c->pfd)) {
360 		case FILE_EXECUTABLE:
361 			start_cgi(path, end+1, c);
362 			return;
363 		case FILE_MISSING:
364 			break;
365 		default:
366 			goto err;
367 		}
368 
369 		*end = '/';
370 		end--;
371 	}
372 
373 err:
374 	start_reply(c, NOT_FOUND, "not found");
375 	return;
376 }
377 
378 void
379 mark_nonblock(int fd)
380 {
381 	int flags;
382 
383 	if ((flags = fcntl(fd, F_GETFL)) == -1)
384 		fatal("fcntl(F_GETFL): %s", strerror(errno));
385 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
386 		fatal("fcntl(F_SETFL): %s", strerror(errno));
387 }
388 
389 static void
390 handle_handshake(int fd, short ev, void *d)
391 {
392 	struct client *c = d;
393 	struct vhost *h;
394 	struct alist *a;
395 	const char *servname;
396 	const char *parse_err = "unknown error";
397 
398 	switch (tls_handshake(c->ctx)) {
399 	case 0:  /* success */
400 	case -1: /* already handshaked */
401 		break;
402 	case TLS_WANT_POLLIN:
403 		yield_read(fd, c, &handle_handshake);
404 		return;
405 	case TLS_WANT_POLLOUT:
406 		yield_write(fd, c, &handle_handshake);
407 		return;
408 	default:
409 		/* unreachable */
410 		abort();
411 	}
412 
413 	servname = tls_conn_servername(c->ctx);
414 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
415 		log_info(c, "puny_decode: %s", parse_err);
416 		goto err;
417 	}
418 
419 	TAILQ_FOREACH(h, &hosts, vhosts) {
420 		if (matches(h->domain, c->domain))
421 			goto found;
422 		TAILQ_FOREACH(a, &h->aliases, aliases) {
423 			if (matches(a->alias, c->domain))
424 				goto found;
425 		}
426 	}
427 
428 found:
429 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
430 	    servname != NULL ? servname : "(null)",
431 	    c->domain,
432 	    h != NULL ? h->domain : "(null)");
433 
434 	if (h != NULL) {
435 		c->host = h;
436 		handle_open_conn(fd, ev, c);
437 		return;
438 	}
439 
440 err:
441 	if (servname != NULL)
442 		strncpy(c->req, servname, sizeof(c->req));
443 	else
444 		strncpy(c->req, "null", sizeof(c->req));
445 
446 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
447 }
448 
449 static char *
450 strip_path(char *path, int strip)
451 {
452 	char *t;
453 
454 	while (strip > 0) {
455 		if ((t = strchr(path, '/')) == NULL) {
456 			path = strchr(path, '\0');
457 			break;
458 		}
459 		path = t;
460 		strip--;
461 	}
462 
463 	return path;
464 }
465 
466 static void
467 fmt_sbuf(const char *fmt, struct client *c, const char *path)
468 {
469 	size_t i;
470         char buf[32];
471 
472 	memset(buf, 0, sizeof(buf));
473 	for (i = 0; *fmt; ++fmt) {
474 		if (i == sizeof(buf)-1 || *fmt == '%') {
475 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
476 			memset(buf, 0, sizeof(buf));
477 			i = 0;
478 		}
479 
480 		if (*fmt != '%') {
481 			buf[i++] = *fmt;
482 			continue;
483 		}
484 
485 		switch (*++fmt) {
486 		case '%':
487 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
488 			break;
489 		case 'p':
490 			strlcat(c->sbuf, path, sizeof(c->sbuf));
491 			break;
492 		case 'q':
493 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
494 			break;
495 		case 'P':
496 			snprintf(buf, sizeof(buf), "%d", conf.port);
497 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
498 			memset(buf, 0, sizeof(buf));
499 			break;
500 		case 'N':
501 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
502 			break;
503 		default:
504 			fatal("%s: unknown fmt specifier %c",
505 			    __func__, *fmt);
506 		}
507 	}
508 
509 	if (i != 0)
510 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
511 }
512 
513 /* 1 if a matching `block return' (and apply it), 0 otherwise */
514 static int
515 apply_block_return(struct client *c)
516 {
517 	const char *fmt, *path;
518 	int code;
519 
520 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
521 		return 0;
522 
523 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
524 	fmt_sbuf(fmt, c, path);
525 
526 	start_reply(c, code, c->sbuf);
527 	return 1;
528 }
529 
530 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
531 static int
532 apply_require_ca(struct client *c)
533 {
534 	X509_STORE	*store;
535 	const uint8_t	*cert;
536 	size_t		 len;
537 
538 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
539 		return 0;
540 
541 	if (!tls_peer_cert_provided(c->ctx)) {
542 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
543 		return 1;
544 	}
545 
546 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
547 	if (!validate_against_ca(store, cert, len)) {
548 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
549 		return 1;
550 	}
551 
552 	return 0;
553 }
554 
555 static void
556 handle_open_conn(int fd, short ev, void *d)
557 {
558 	struct client *c = d;
559 	const char *parse_err = "invalid request";
560 	char decoded[DOMAIN_NAME_LEN];
561 
562 	bzero(c->req, sizeof(c->req));
563 	bzero(&c->iri, sizeof(c->iri));
564 
565 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
566 	case -1:
567 		log_err(c, "tls_read: %s", tls_error(c->ctx));
568 		close_conn(fd, ev, c);
569 		return;
570 
571 	case TLS_WANT_POLLIN:
572 		yield_read(fd, c, &handle_open_conn);
573 		return;
574 
575 	case TLS_WANT_POLLOUT:
576 		yield_write(fd, c, &handle_open_conn);
577 		return;
578 	}
579 
580 	if (!trim_req_iri(c->req, &parse_err)
581 	    || !parse_iri(c->req, &c->iri, &parse_err)
582 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
583 		log_info(c, "iri parse error: %s", parse_err);
584 		start_reply(c, BAD_REQUEST, "invalid request");
585 		return;
586 	}
587 
588 	if (c->iri.port_no != conf.port
589 	    || strcmp(c->iri.schema, "gemini")
590 	    || strcmp(decoded, c->domain)) {
591 		start_reply(c, PROXY_REFUSED, "won't proxy request");
592 		return;
593 	}
594 
595 	if (apply_require_ca(c))
596 		return;
597 
598 	if (apply_block_return(c))
599 		return;
600 
601 	if (c->host->entrypoint != NULL) {
602 		start_cgi(c->host->entrypoint, c->iri.path, c);
603 		return;
604 	}
605 
606 	open_file(c);
607 }
608 
609 static void
610 start_reply(struct client *c, int code, const char *meta)
611 {
612 	c->code = code;
613 	c->meta = meta;
614 	handle_start_reply(c->fd, 0, c);
615 }
616 
617 static void
618 handle_start_reply(int fd, short ev, void *d)
619 {
620 	struct client *c = d;
621 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
622 	const char *lang;
623 	size_t len;
624 
625 	lang = vhost_lang(c->host, c->iri.path);
626 
627 	snprintf(buf, sizeof(buf), "%d ", c->code);
628 	strlcat(buf, c->meta, sizeof(buf));
629 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
630 		strlcat(buf, "; lang=", sizeof(buf));
631 		strlcat(buf, lang, sizeof(buf));
632 	}
633 
634 	len = strlcat(buf, "\r\n", sizeof(buf));
635 	assert(len < sizeof(buf));
636 
637 	switch (tls_write(c->ctx, buf, len)) {
638 	case -1:
639 		close_conn(fd, ev, c);
640 		return;
641 	case TLS_WANT_POLLIN:
642 		yield_read(fd, c, &handle_start_reply);
643 		return;
644 	case TLS_WANT_POLLOUT:
645 		yield_write(fd, c, &handle_start_reply);
646 		return;
647 	}
648 
649 	if (!vhost_disable_log(c->host, c->iri.path))
650 		log_request(c, buf, sizeof(buf));
651 
652 	if (c->code != SUCCESS)
653 		close_conn(fd, ev, c);
654 	else
655 		c->next(fd, ev, c);
656 }
657 
658 static size_t
659 host_nth(struct vhost *h)
660 {
661 	struct vhost	*v;
662 	size_t		 i = 0;
663 
664 	TAILQ_FOREACH(v, &hosts, vhosts) {
665 		if (v == h)
666 			return i;
667 		i++;
668 	}
669 
670 	abort();
671 }
672 
673 static void
674 start_cgi(const char *spath, const char *relpath, struct client *c)
675 {
676 	char addr[NI_MAXHOST];
677 	const char *t;
678 	struct cgireq req;
679 	int e;
680 
681 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
682 	    addr, sizeof(addr),
683 	    NULL, 0,
684 	    NI_NUMERICHOST);
685 	if (e != 0)
686 		fatal("getnameinfo failed");
687 
688 	memset(&req, 0, sizeof(req));
689 
690 	memcpy(req.buf, c->req, sizeof(req.buf));
691 
692 	req.iri_schema_off = c->iri.schema - c->req;
693 	req.iri_host_off = c->iri.host - c->req;
694 	req.iri_port_off = c->iri.port - c->req;
695 	req.iri_path_off = c->iri.path - c->req;
696 	req.iri_query_off = c->iri.query - c->req;
697 	req.iri_fragment_off = c->iri.fragment - c->req;
698 
699 	req.iri_portno = c->iri.port_no;
700 
701 	strlcpy(req.spath, spath, sizeof(req.spath));
702 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
703 	strlcpy(req.addr, addr, sizeof(req.addr));
704 
705 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
706 		strlcpy(req.subject, t, sizeof(req.subject));
707 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
708 		strlcpy(req.issuer, t, sizeof(req.issuer));
709 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
710 		strlcpy(req.hash, t, sizeof(req.hash));
711 	if ((t = tls_conn_version(c->ctx)) != NULL)
712 		strlcpy(req.version, t, sizeof(req.version));
713 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
714 		strlcpy(req.cipher, t, sizeof(req.cipher));
715 
716 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
717 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
718 	req.notafter = tls_peer_cert_notafter(c->ctx);
719 
720 	req.host_off = host_nth(c->host);
721 
722 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
723 	imsg_flush(&exibuf);
724 
725 	close(c->pfd);
726 }
727 
728 static void
729 open_dir(struct client *c)
730 {
731 	size_t len;
732 	int dirfd, root;
733 	char *before_file;
734 
735 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
736 
737 	len = strlen(c->iri.path);
738 	if (len > 0 && !ends_with(c->iri.path, "/")) {
739 		redirect_canonical_dir(c);
740 		return;
741 	}
742 
743 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
744 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
745 	if (!ends_with(c->sbuf, "/"))
746 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
747 	before_file = strchr(c->sbuf, '\0');
748 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
749 	    sizeof(c->sbuf));
750 	if (len >= sizeof(c->sbuf)) {
751 		start_reply(c, TEMP_FAILURE, "internal server error");
752 		return;
753 	}
754 
755 	c->iri.path = c->sbuf;
756 
757 	/* close later unless we have to generate the dir listing */
758 	dirfd = c->pfd;
759 	c->pfd = -1;
760 
761 	switch (check_path(c, c->iri.path, &c->pfd)) {
762 	case FILE_EXECUTABLE:
763 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
764 			start_cgi(c->iri.path, "", c);
765 			break;
766 		}
767 
768 		/* fallthrough */
769 
770 	case FILE_EXISTS:
771 		c->next = handle_copy;
772 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
773 		break;
774 
775 	case FILE_DIRECTORY:
776 		start_reply(c, TEMP_REDIRECT, c->sbuf);
777 		break;
778 
779 	case FILE_MISSING:
780 		*before_file = '\0';
781 
782 		if (!vhost_auto_index(c->host, c->iri.path)) {
783 			start_reply(c, NOT_FOUND, "not found");
784 			break;
785 		}
786 
787 		c->next = enter_handle_dirlist;
788 
789 		c->dirlen = scandir_fd(dirfd, &c->dir,
790 		    root ? select_non_dotdot : select_non_dot,
791 		    alphasort);
792 		if (c->dirlen == -1) {
793 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
794 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
795 			start_reply(c, TEMP_FAILURE, "internal server error");
796 			return;
797 		}
798 		c->diroff = 0;
799 		c->off = 0;
800 
801                 start_reply(c, SUCCESS, "text/gemini");
802 		return;
803 
804 	default:
805 		/* unreachable */
806 		abort();
807 	}
808 
809 	close(dirfd);
810 }
811 
812 static void
813 redirect_canonical_dir(struct client *c)
814 {
815 	size_t len;
816 
817 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
818 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
819 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
820 
821 	if (len >= sizeof(c->sbuf)) {
822 		start_reply(c, TEMP_FAILURE, "internal server error");
823 		return;
824 	}
825 
826 	start_reply(c, TEMP_REDIRECT, c->sbuf);
827 }
828 
829 static void
830 enter_handle_dirlist(int fd, short ev, void *d)
831 {
832 	struct client *c = d;
833 	char b[PATH_MAX];
834 	size_t l;
835 
836 	strlcpy(b, c->iri.path, sizeof(b));
837 	l = snprintf(c->sbuf, sizeof(c->sbuf),
838 	    "# Index of %s\n\n", b);
839 	if (l >= sizeof(c->sbuf)) {
840 		/* this is impossible, given that we have enough space
841 		 * in c->sbuf to hold the ancilliary string plus the
842 		 * full path; but it wouldn't read nice without some
843 		 * error checking, and I'd like to avoid a strlen. */
844 		close_conn(fd, ev, c);
845 		return;
846 	}
847 
848 	c->len = l;
849 	handle_dirlist(fd, ev, c);
850 }
851 
852 static void
853 handle_dirlist(int fd, short ev, void *d)
854 {
855 	struct client *c = d;
856 	ssize_t r;
857 
858 	while (c->len > 0) {
859 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
860 		case -1:
861 			close_conn(fd, ev, c);
862 			return;
863 		case TLS_WANT_POLLOUT:
864 			yield_read(fd, c, &handle_dirlist);
865 			return;
866 		case TLS_WANT_POLLIN:
867 			yield_write(fd, c, &handle_dirlist);
868 			return;
869 		default:
870 			c->off += r;
871 			c->len -= r;
872 		}
873 	}
874 
875 	send_directory_listing(fd, ev, c);
876 }
877 
878 static int
879 read_next_dir_entry(struct client *c)
880 {
881 	if (c->diroff == c->dirlen)
882 		return 0;
883 
884 	/* XXX: url escape */
885 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s\n",
886 	    c->dir[c->diroff]->d_name);
887 
888 	free(c->dir[c->diroff]);
889 	c->diroff++;
890 
891 	c->len = strlen(c->sbuf);
892 	c->off = 0;
893 	return 1;
894 }
895 
896 static void
897 send_directory_listing(int fd, short ev, void *d)
898 {
899 	struct client *c = d;
900 	ssize_t r;
901 
902 	while (1) {
903 		if (c->len == 0) {
904 			if (!read_next_dir_entry(c))
905 				goto end;
906 		}
907 
908 		while (c->len > 0) {
909 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
910 			case -1:
911 				goto end;
912 
913 			case TLS_WANT_POLLOUT:
914 				yield_read(fd, c, &send_directory_listing);
915 				return;
916 
917 			case TLS_WANT_POLLIN:
918 				yield_write(fd, c, &send_directory_listing);
919 				return;
920 
921 			default:
922 				c->off += r;
923 				c->len -= r;
924 				break;
925 			}
926 		}
927 	}
928 
929 end:
930 	close_conn(fd, ev, d);
931 }
932 
933 /* accumulate the meta line from the cgi script. */
934 static void
935 handle_cgi_reply(int fd, short ev, void *d)
936 {
937 	struct client *c = d;
938 	void	*buf, *e;
939 	size_t	 len;
940 	ssize_t	 r;
941 
942 
943 	buf = c->sbuf + c->len;
944 	len = sizeof(c->sbuf) - c->len;
945 
946 	r = read(c->pfd, buf, len);
947 	if (r == 0 || r == -1) {
948 		start_reply(c, CGI_ERROR, "CGI error");
949 		return;
950 	}
951 
952 	c->len += r;
953 
954 	/* TODO: error if the CGI script don't reply correctly */
955 	e = strchr(c->sbuf, '\n');
956 	if (e != NULL || c->len == sizeof(c->sbuf)) {
957 		log_request(c, c->sbuf, c->len);
958 
959 		c->off = 0;
960 		handle_copy(fd, ev, c);
961 		return;
962 	}
963 
964 	yield_read(fd, c, &handle_cgi_reply);
965 }
966 
967 static void
968 handle_copy(int fd, short ev, void *d)
969 {
970 	struct client *c = d;
971 	ssize_t r;
972 
973 	while (1) {
974 		while (c->len > 0) {
975 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
976 			case -1:
977 				goto end;
978 
979 			case TLS_WANT_POLLOUT:
980 				yield_write(c->fd, c, &handle_copy);
981 				return;
982 
983 			case TLS_WANT_POLLIN:
984 				yield_read(c->fd, c, &handle_copy);
985 				return;
986 
987 			default:
988                                 c->off += r;
989 				c->len -= r;
990 				break;
991 			}
992 		}
993 
994 		switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
995 		case 0:
996 			goto end;
997 		case -1:
998 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
999 				yield_read(c->pfd, c, &handle_copy);
1000 				return;
1001 			}
1002 			goto end;
1003 		default:
1004 			c->len = r;
1005 			c->off = 0;
1006 		}
1007 	}
1008 
1009 end:
1010 	close_conn(c->fd, ev, d);
1011 }
1012 
1013 static void
1014 close_conn(int fd, short ev, void *d)
1015 {
1016 	struct client *c = d;
1017 
1018 	switch (tls_close(c->ctx)) {
1019 	case TLS_WANT_POLLIN:
1020 		yield_read(fd, c, &close_conn);
1021 		return;
1022 	case TLS_WANT_POLLOUT:
1023 		yield_read(fd, c, &close_conn);
1024 		return;
1025 	}
1026 
1027 	connected_clients--;
1028 
1029 	tls_free(c->ctx);
1030 	c->ctx = NULL;
1031 
1032 	if (c->pfd != -1)
1033 		close(c->pfd);
1034 
1035 	if (c->dir != NULL)
1036 		free(c->dir);
1037 
1038 	close(c->fd);
1039 	c->fd = -1;
1040 }
1041 
1042 static void
1043 do_accept(int sock, short et, void *d)
1044 {
1045 	struct client *c;
1046 	struct sockaddr_storage addr;
1047 	struct sockaddr *saddr;
1048 	socklen_t len;
1049 	int i, fd;
1050 
1051 	(void)et;
1052 
1053 	saddr = (struct sockaddr*)&addr;
1054 	len = sizeof(addr);
1055 	if ((fd = accept(sock, saddr, &len)) == -1) {
1056 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1057 			return;
1058 		fatal("accept: %s", strerror(errno));
1059 	}
1060 
1061 	mark_nonblock(fd);
1062 
1063 	for (i = 0; i < MAX_USERS; ++i) {
1064 		c = &clients[i];
1065 		if (c->fd == -1) {
1066 			memset(c, 0, sizeof(*c));
1067 			c->id = i;
1068 			if (tls_accept_socket(ctx, &c->ctx, fd) == -1)
1069 				break; /* goodbye fd! */
1070 
1071 			c->fd = fd;
1072 			c->pfd = -1;
1073 			c->dir = NULL;
1074 			c->addr = addr;
1075 
1076 			yield_read(fd, c, &handle_handshake);
1077 			connected_clients++;
1078 			return;
1079 		}
1080 	}
1081 
1082 	close(fd);
1083 }
1084 
1085 struct client *
1086 client_by_id(int id)
1087 {
1088 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1089 		fatal("in client_by_id: invalid id %d", id);
1090 	return &clients[id];
1091 }
1092 
1093 static void
1094 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1095 {
1096 	struct client *c;
1097 
1098 	c = client_by_id(imsg->hdr.peerid);
1099 
1100 	if ((c->pfd = imsg->fd) == -1)
1101 		start_reply(c, TEMP_FAILURE, "internal server error");
1102 	else
1103 		yield_read(c->pfd, c, &handle_cgi_reply);
1104 }
1105 
1106 static void
1107 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1108 {
1109 	(void)imsg;
1110 	(void)len;
1111 
1112 	/* don't call event_loopbreak since we want to finish to
1113 	 * handle the ongoing connections. */
1114 
1115 	event_del(&e4);
1116 	if (has_ipv6)
1117 		event_del(&e6);
1118 	if (has_siginfo)
1119 		signal_del(&siginfo);
1120 	event_del(&imsgev);
1121 	signal_del(&sigusr2);
1122 }
1123 
1124 static void
1125 handle_dispatch_imsg(int fd, short ev, void *d)
1126 {
1127 	struct imsgbuf *ibuf = d;
1128 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1129 }
1130 
1131 static void
1132 handle_siginfo(int fd, short ev, void *d)
1133 {
1134 	(void)fd;
1135 	(void)ev;
1136 	(void)d;
1137 
1138 	log_info(NULL, "%d connected clients", connected_clients);
1139 }
1140 
1141 void
1142 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1143 {
1144 	size_t i;
1145 
1146 	ctx = ctx_;
1147 
1148 	event_init();
1149 
1150 	memset(&clients, 0, sizeof(clients));
1151 	for (i = 0; i < MAX_USERS; ++i)
1152 		clients[i].fd = -1;
1153 
1154 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1155 	event_add(&e4, NULL);
1156 
1157 	if (sock6 != -1) {
1158 		has_ipv6 = 1;
1159 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1160 		event_add(&e6, NULL);
1161 	}
1162 
1163 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1164 	event_add(&imsgev, NULL);
1165 
1166 #ifdef SIGINFO
1167 	has_siginfo = 1;
1168 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1169 	signal_add(&siginfo, NULL);
1170 #endif
1171 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1172 	signal_add(&sigusr2, NULL);
1173 
1174 	sandbox_server_process();
1175 	event_dispatch();
1176 	_exit(0);
1177 }