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 <ctype.h>
23 #include <errno.h>
24 #include <event.h>
25 #include <fcntl.h>
26 #include <fnmatch.h>
27 #include <limits.h>
28 #include <string.h>
29 
30 #define MIN(a, b)	((a) < (b) ? (a) : (b))
31 
32 int shutting_down;
33 
34 struct client	 clients[MAX_USERS];
35 
36 static struct tls	*ctx;
37 
38 static struct event e4, e6, imsgev, siginfo, sigusr2;
39 static int has_ipv6, has_siginfo;
40 
41 int connected_clients;
42 
43 static inline int matches(const char*, const char*);
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_fastcgi(struct client*);
53 static int	 apply_require_ca(struct client*);
54 static size_t	 host_nth(struct vhost*);
55 static void	 start_cgi(const char*, const char*, struct client*);
56 static void	 open_dir(struct client*);
57 static void	 redirect_canonical_dir(struct client*);
58 
59 static void	 client_tls_readcb(int, short, void *);
60 static void	 client_tls_writecb(int, short, void *);
61 
62 static void	 client_read(struct bufferevent *, void *);
63 void		 client_write(struct bufferevent *, void *);
64 static void	 client_error(struct bufferevent *, short, void *);
65 
66 static void	 client_close_ev(int, short, void *);
67 
68 static void	 cgi_read(struct bufferevent *, void *);
69 static void	 cgi_write(struct bufferevent *, void *);
70 static void	 cgi_error(struct bufferevent *, short, void *);
71 
72 static void	 do_accept(int, short, void*);
73 static struct client *client_by_id(int);
74 
75 static void	 handle_imsg_cgi_res(struct imsgbuf*, struct imsg*, size_t);
76 static void	 handle_imsg_fcgi_fd(struct imsgbuf*, struct imsg*, size_t);
77 static void	 handle_imsg_quit(struct imsgbuf*, struct imsg*, size_t);
78 static void	 handle_dispatch_imsg(int, short, void *);
79 static void	 handle_siginfo(int, short, void*);
80 
81 static imsg_handlerfn *handlers[] = {
82 	[IMSG_QUIT] = handle_imsg_quit,
83 	[IMSG_CGI_RES] = handle_imsg_cgi_res,
84 	[IMSG_FCGI_FD] = handle_imsg_fcgi_fd,
85 };
86 
87 static inline int
88 matches(const char *pattern, const char *path)
89 {
90 	if (*path == '/')
91 		path++;
92 	return !fnmatch(pattern, path, 0);
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 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 	if (*fd == -1 && (*fd = openat(dirfd, p, O_RDONLY)) == -1)
334 		return FILE_MISSING;
335 
336 	if (fstat(*fd, &sb) == -1) {
337 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
338 		return FILE_MISSING;
339 	}
340 
341 	if (S_ISDIR(sb.st_mode))
342 		return FILE_DIRECTORY;
343 
344 	if (sb.st_mode & S_IXUSR)
345 		return FILE_EXECUTABLE;
346 
347 	return FILE_EXISTS;
348 }
349 
350 static void
351 open_file(struct client *c)
352 {
353 	switch (check_path(c, c->iri.path, &c->pfd)) {
354 	case FILE_EXECUTABLE:
355 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
356 			start_cgi(c->iri.path, "", c);
357 			return;
358 		}
359 
360 		/* fallthrough */
361 
362 	case FILE_EXISTS:
363 		c->type = REQUEST_FILE;
364 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
365 		return;
366 
367 	case FILE_DIRECTORY:
368 		open_dir(c);
369 		return;
370 
371 	case FILE_MISSING:
372 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
373 			check_for_cgi(c);
374 			return;
375 		}
376 		start_reply(c, NOT_FOUND, "not found");
377 		return;
378 
379 	default:
380 		/* unreachable */
381 		abort();
382 	}
383 }
384 
385 /*
386  * the inverse of this algorithm, i.e. starting from the start of the
387  * path + strlen(cgi), and checking if each component, should be
388  * faster.  But it's tedious to write.  This does the opposite: starts
389  * from the end and strip one component at a time, until either an
390  * executable is found or we emptied the path.
391  */
392 static void
393 check_for_cgi(struct client *c)
394 {
395 	char path[PATH_MAX];
396 	char *end;
397 
398 	strlcpy(path, c->iri.path, sizeof(path));
399 	end = strchr(path, '\0');
400 
401 	while (end > path) {
402 		/*
403 		 * go up one level.  UNIX paths are simple and POSIX
404 		 * dirname, with its ambiguities on if the given
405 		 * pointer is changed or not, gives me headaches.
406 		 */
407 		while (*end != '/' && end > path)
408 			end--;
409 
410 		if (end == path)
411 			break;
412 
413 		*end = '\0';
414 
415 		switch (check_path(c, path, &c->pfd)) {
416 		case FILE_EXECUTABLE:
417 			start_cgi(path, end+1, c);
418 			return;
419 		case FILE_MISSING:
420 			break;
421 		default:
422 			goto err;
423 		}
424 
425 		*end = '/';
426 		end--;
427 	}
428 
429 err:
430 	start_reply(c, NOT_FOUND, "not found");
431 	return;
432 }
433 
434 void
435 mark_nonblock(int fd)
436 {
437 	int flags;
438 
439 	if ((flags = fcntl(fd, F_GETFL)) == -1)
440 		fatal("fcntl(F_GETFL): %s", strerror(errno));
441 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
442 		fatal("fcntl(F_SETFL): %s", strerror(errno));
443 }
444 
445 static void
446 handle_handshake(int fd, short ev, void *d)
447 {
448 	struct client *c = d;
449 	struct vhost *h;
450 	struct alist *a;
451 	const char *servname;
452 	const char *parse_err = "unknown error";
453 
454 	switch (tls_handshake(c->ctx)) {
455 	case 0:  /* success */
456 	case -1: /* already handshaked */
457 		break;
458 	case TLS_WANT_POLLIN:
459 		event_once(c->fd, EV_READ, handle_handshake, c, NULL);
460 		return;
461 	case TLS_WANT_POLLOUT:
462 		event_once(c->fd, EV_WRITE, handle_handshake, c, NULL);
463 		return;
464 	default:
465 		/* unreachable */
466 		abort();
467 	}
468 
469 	if ((servname = tls_conn_servername(c->ctx)) == NULL) {
470 		log_debug(c, "handshake: missing SNI");
471 		goto err;
472 	}
473 
474 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
475 		log_info(c, "puny_decode: %s", parse_err);
476 		goto err;
477 	}
478 
479 	TAILQ_FOREACH(h, &hosts, vhosts) {
480 		if (matches(h->domain, c->domain))
481 			goto found;
482 		TAILQ_FOREACH(a, &h->aliases, aliases) {
483 			if (matches(a->alias, c->domain))
484 				goto found;
485 		}
486 	}
487 
488 found:
489 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
490 	    servname != NULL ? servname : "(null)",
491 	    c->domain,
492 	    h != NULL ? h->domain : "(null)");
493 
494 	if (h != NULL) {
495 		c->host = h;
496 
497 		c->bev = bufferevent_new(fd, client_read, client_write,
498 		    client_error, c);
499 		if (c->bev == NULL)
500 			fatal("%s: failed to allocate client buffer: %s",
501 			    __func__, strerror(errno));
502 
503 		event_set(&c->bev->ev_read, c->fd, EV_READ,
504 		    client_tls_readcb, c->bev);
505 		event_set(&c->bev->ev_write, c->fd, EV_WRITE,
506 		    client_tls_writecb, c->bev);
507 
508 #if HAVE_LIBEVENT2
509 		evbuffer_unfreeze(c->bev->input, 0);
510 		evbuffer_unfreeze(c->bev->output, 1);
511 #endif
512 
513 		bufferevent_enable(c->bev, EV_READ);
514 
515 		return;
516 	}
517 
518 err:
519 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
520 }
521 
522 static const char *
523 strip_path(const char *path, int strip)
524 {
525 	char *t;
526 
527 	while (strip > 0) {
528 		if ((t = strchr(path, '/')) == NULL) {
529 			path = strchr(path, '\0');
530 			break;
531 		}
532 		path = t;
533 		strip--;
534 	}
535 
536 	return path;
537 }
538 
539 static void
540 fmt_sbuf(const char *fmt, struct client *c, const char *path)
541 {
542 	size_t i;
543         char buf[32];
544 
545 	memset(buf, 0, sizeof(buf));
546 	for (i = 0; *fmt; ++fmt) {
547 		if (i == sizeof(buf)-1 || *fmt == '%') {
548 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
549 			memset(buf, 0, sizeof(buf));
550 			i = 0;
551 		}
552 
553 		if (*fmt != '%') {
554 			buf[i++] = *fmt;
555 			continue;
556 		}
557 
558 		switch (*++fmt) {
559 		case '%':
560 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
561 			break;
562 		case 'p':
563 			if (*path != '/')
564 				strlcat(c->sbuf, "/", sizeof(c->sbuf));
565 			strlcat(c->sbuf, path, sizeof(c->sbuf));
566 			break;
567 		case 'q':
568 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
569 			break;
570 		case 'P':
571 			snprintf(buf, sizeof(buf), "%d", conf.port);
572 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
573 			memset(buf, 0, sizeof(buf));
574 			break;
575 		case 'N':
576 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
577 			break;
578 		default:
579 			fatal("%s: unknown fmt specifier %c",
580 			    __func__, *fmt);
581 		}
582 	}
583 
584 	if (i != 0)
585 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
586 }
587 
588 /* 1 if a matching `block return' (and apply it), 0 otherwise */
589 static int
590 apply_block_return(struct client *c)
591 {
592 	const char *fmt, *path;
593 	int code;
594 
595 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
596 		return 0;
597 
598 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
599 	fmt_sbuf(fmt, c, path);
600 
601 	start_reply(c, code, c->sbuf);
602 	return 1;
603 }
604 
605 /* 1 if matching `fcgi' (and apply it), 0 otherwise */
606 static int
607 apply_fastcgi(struct client *c)
608 {
609 	int		 id;
610 	struct fcgi	*f;
611 
612 	if ((id = vhost_fastcgi(c->host, c->iri.path)) == -1)
613 		return 0;
614 
615 	f = &fcgi[id];
616 
617 	log_debug(c, "opening fastcgi connection for (%s,%s,%s)",
618 	    f->path, f->port, f->prog);
619 
620 	imsg_compose(&exibuf, IMSG_FCGI_REQ, c->id, 0, -1,
621 	    &id, sizeof(id));
622 	imsg_flush(&exibuf);
623 	return 1;
624 }
625 
626 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
627 static int
628 apply_require_ca(struct client *c)
629 {
630 	X509_STORE	*store;
631 	const uint8_t	*cert;
632 	size_t		 len;
633 
634 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
635 		return 0;
636 
637 	if (!tls_peer_cert_provided(c->ctx)) {
638 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
639 		return 1;
640 	}
641 
642 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
643 	if (!validate_against_ca(store, cert, len)) {
644 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
645 		return 1;
646 	}
647 
648 	return 0;
649 }
650 
651 static size_t
652 host_nth(struct vhost *h)
653 {
654 	struct vhost	*v;
655 	size_t		 i = 0;
656 
657 	TAILQ_FOREACH(v, &hosts, vhosts) {
658 		if (v == h)
659 			return i;
660 		i++;
661 	}
662 
663 	abort();
664 }
665 
666 static void
667 start_cgi(const char *spath, const char *relpath, struct client *c)
668 {
669 	char addr[NI_MAXHOST];
670 	const char *t;
671 	struct cgireq req;
672 	int e;
673 
674 	c->type = REQUEST_CGI;
675 
676 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
677 	    addr, sizeof(addr),
678 	    NULL, 0,
679 	    NI_NUMERICHOST);
680 	if (e != 0)
681 		fatal("getnameinfo failed");
682 
683 	memset(&req, 0, sizeof(req));
684 
685 	memcpy(req.buf, c->req, sizeof(req.buf));
686 
687 	req.iri_schema_off = c->iri.schema - c->req;
688 	req.iri_host_off = c->iri.host - c->req;
689 	req.iri_port_off = c->iri.port - c->req;
690 	req.iri_path_off = c->iri.path - c->req;
691 	req.iri_query_off = c->iri.query - c->req;
692 	req.iri_fragment_off = c->iri.fragment - c->req;
693 
694 	req.iri_portno = c->iri.port_no;
695 
696 	strlcpy(req.spath, spath, sizeof(req.spath));
697 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
698 	strlcpy(req.addr, addr, sizeof(req.addr));
699 
700 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
701 		strlcpy(req.subject, t, sizeof(req.subject));
702 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
703 		strlcpy(req.issuer, t, sizeof(req.issuer));
704 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
705 		strlcpy(req.hash, t, sizeof(req.hash));
706 	if ((t = tls_conn_version(c->ctx)) != NULL)
707 		strlcpy(req.version, t, sizeof(req.version));
708 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
709 		strlcpy(req.cipher, t, sizeof(req.cipher));
710 
711 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
712 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
713 	req.notafter = tls_peer_cert_notafter(c->ctx);
714 
715 	req.host_off = host_nth(c->host);
716 	req.loc_off = c->loc;
717 
718 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
719 	imsg_flush(&exibuf);
720 
721 	close(c->pfd);
722 }
723 
724 static void
725 open_dir(struct client *c)
726 {
727 	size_t len;
728 	int dirfd, root;
729 	char *before_file;
730 
731 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
732 
733 	len = strlen(c->iri.path);
734 	if (len > 0 && !ends_with(c->iri.path, "/")) {
735 		redirect_canonical_dir(c);
736 		return;
737 	}
738 
739 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
740 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
741 	if (!ends_with(c->sbuf, "/"))
742 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
743 	before_file = strchr(c->sbuf, '\0');
744 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
745 	    sizeof(c->sbuf));
746 	if (len >= sizeof(c->sbuf)) {
747 		start_reply(c, TEMP_FAILURE, "internal server error");
748 		return;
749 	}
750 
751 	c->iri.path = c->sbuf;
752 
753 	/* close later unless we have to generate the dir listing */
754 	dirfd = c->pfd;
755 	c->pfd = -1;
756 
757 	switch (check_path(c, c->iri.path, &c->pfd)) {
758 	case FILE_EXECUTABLE:
759 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
760 			start_cgi(c->iri.path, "", c);
761 			break;
762 		}
763 
764 		/* fallthrough */
765 
766 	case FILE_EXISTS:
767 		c->type = REQUEST_FILE;
768 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
769 		break;
770 
771 	case FILE_DIRECTORY:
772 		start_reply(c, TEMP_REDIRECT, c->sbuf);
773 		break;
774 
775 	case FILE_MISSING:
776 		*before_file = '\0';
777 
778 		if (!vhost_auto_index(c->host, c->iri.path)) {
779 			start_reply(c, NOT_FOUND, "not found");
780 			break;
781 		}
782 
783 		c->type = REQUEST_DIR;
784 
785 		c->dirlen = scandir_fd(dirfd, &c->dir,
786 		    root ? select_non_dotdot : select_non_dot,
787 		    alphasort);
788 		if (c->dirlen == -1) {
789 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
790 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
791 			start_reply(c, TEMP_FAILURE, "internal server error");
792 			return;
793 		}
794 		c->diroff = 0;
795 		c->off = 0;
796 
797                 start_reply(c, SUCCESS, "text/gemini");
798 		evbuffer_add_printf(EVBUFFER_OUTPUT(c->bev),
799 		    "# Index of %s\n\n", c->iri.path);
800 		return;
801 
802 	default:
803 		/* unreachable */
804 		abort();
805 	}
806 
807 	close(dirfd);
808 }
809 
810 static void
811 redirect_canonical_dir(struct client *c)
812 {
813 	size_t len;
814 
815 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
816 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
817 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
818 
819 	if (len >= sizeof(c->sbuf)) {
820 		start_reply(c, TEMP_FAILURE, "internal server error");
821 		return;
822 	}
823 
824 	start_reply(c, TEMP_REDIRECT, c->sbuf);
825 }
826 
827 static void
828 client_tls_readcb(int fd, short event, void *d)
829 {
830 	struct bufferevent	*bufev = d;
831 	struct client		*client = bufev->cbarg;
832 	ssize_t			 ret;
833 	size_t			 len;
834 	int			 what = EVBUFFER_READ;
835 	int			 howmuch = IBUF_READ_SIZE;
836 	char			 buf[IBUF_READ_SIZE];
837 
838 	if (event == EV_TIMEOUT) {
839 		what |= EVBUFFER_TIMEOUT;
840 		goto err;
841 	}
842 
843 	if (bufev->wm_read.high != 0)
844 		howmuch = MIN(sizeof(buf), bufev->wm_read.high);
845 
846 	switch (ret = tls_read(client->ctx, buf, howmuch)) {
847 	case TLS_WANT_POLLIN:
848 	case TLS_WANT_POLLOUT:
849 		goto retry;
850 	case -1:
851 		what |= EVBUFFER_ERROR;
852 		goto err;
853 	}
854 	len = ret;
855 
856 	if (len == 0) {
857 		what |= EVBUFFER_EOF;
858 		goto err;
859 	}
860 
861 	if (evbuffer_add(bufev->input, buf, len) == -1) {
862 		what |= EVBUFFER_ERROR;
863 		goto err;
864 	}
865 
866 	event_add(&bufev->ev_read, NULL);
867 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
868 		return;
869 	if (bufev->wm_read.high != 0 && len > bufev->wm_read.high) {
870 		/*
871 		 * here we could implement a read pressure policy.
872 		 */
873 	}
874 
875 	if (bufev->readcb != NULL)
876 		(*bufev->readcb)(bufev, bufev->cbarg);
877 
878 	return;
879 
880 retry:
881 	event_add(&bufev->ev_read, NULL);
882 	return;
883 
884 err:
885 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
886 }
887 
888 static void
889 client_tls_writecb(int fd, short event, void *d)
890 {
891 	struct bufferevent	*bufev = d;
892 	struct client		*client = bufev->cbarg;
893 	ssize_t			 ret;
894 	size_t			 len;
895 	short			 what = EVBUFFER_WRITE;
896 
897 	if (event == EV_TIMEOUT) {
898 		what |= EVBUFFER_TIMEOUT;
899 		goto err;
900 	}
901 
902 	if (EVBUFFER_LENGTH(bufev->output) != 0) {
903 		ret = tls_write(client->ctx,
904 		    EVBUFFER_DATA(bufev->output),
905 		    EVBUFFER_LENGTH(bufev->output));
906 		switch (ret) {
907 		case TLS_WANT_POLLIN:
908 		case TLS_WANT_POLLOUT:
909 			goto retry;
910 		case -1:
911 			what |= EVBUFFER_ERROR;
912 			goto err;
913 		}
914 		len = ret;
915 		evbuffer_drain(bufev->output, len);
916 	}
917 
918 	if (EVBUFFER_LENGTH(bufev->output) != 0)
919 		event_add(&bufev->ev_write, NULL);
920 
921 	if (bufev->writecb != NULL &&
922 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
923 		(*bufev->writecb)(bufev, bufev->cbarg);
924 	return;
925 
926 retry:
927 	event_add(&bufev->ev_write, NULL);
928 	return;
929 err:
930 	log_err(client, "tls error: %s", tls_error(client->ctx));
931 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
932 }
933 
934 static void
935 client_read(struct bufferevent *bev, void *d)
936 {
937 	struct client	*c = d;
938 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
939 	const char	*parse_err = "invalid request";
940 	char		 decoded[DOMAIN_NAME_LEN];
941 	size_t		 len;
942 
943 	bufferevent_disable(bev, EVBUFFER_READ);
944 
945 	/* max url len + \r\n */
946 	if (EVBUFFER_LENGTH(src) > 1024 + 2) {
947 		log_err(c, "too much data received");
948 		start_reply(c, BAD_REQUEST, "bad request");
949 		return;
950 	}
951 
952 	c->req = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
953 	if (c->req == NULL) {
954 		/* not enough data yet. */
955 		bufferevent_enable(bev, EVBUFFER_READ);
956 		return;
957 	}
958 
959 	if (!parse_iri(c->req, &c->iri, &parse_err) ||
960 	    !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
961 		log_err(c, "IRI parse error: %s", parse_err);
962 		start_reply(c, BAD_REQUEST, "bad request");
963 		return;
964 	}
965 
966 	if (c->iri.port_no != conf.port ||
967 	    strcmp(c->iri.schema, "gemini") ||
968 	    strcmp(decoded, c->domain)) {
969 		start_reply(c, PROXY_REFUSED, "won't proxy request");
970 		return;
971 	}
972 
973 	if (apply_require_ca(c) ||
974 	    apply_block_return(c)||
975 	    apply_fastcgi(c))
976 		return;
977 
978 	if (c->host->entrypoint != NULL) {
979 		c->loc = 0;
980 		start_cgi(c->host->entrypoint, c->iri.path, c);
981 		return;
982 	}
983 
984 	open_file(c);
985 }
986 
987 void
988 client_write(struct bufferevent *bev, void *d)
989 {
990 	struct client	*c = d;
991 	struct evbuffer	*out = EVBUFFER_OUTPUT(bev);
992 	char		 buf[BUFSIZ];
993 	ssize_t		 r;
994 
995 	switch (c->type) {
996 	case REQUEST_UNDECIDED:
997 		/*
998 		 * Ignore spurious calls when we still don't have idea
999 		 * what to do with the request.
1000 		 */
1001 		break;
1002 
1003 	case REQUEST_FILE:
1004 		if ((r = read(c->pfd, buf, sizeof(buf))) == -1) {
1005 			log_warn(c, "read: %s", strerror(errno));
1006 			client_error(bev, EVBUFFER_ERROR, c);
1007 			return;
1008 		} else if (r == 0) {
1009 			client_close(c);
1010 			return;
1011 		} else if (r != sizeof(buf))
1012 			c->type = REQUEST_DONE;
1013 		bufferevent_write(bev, buf, r);
1014 		break;
1015 
1016 	case REQUEST_DIR:
1017 		/* TODO: handle big big directories better */
1018 		for (c->diroff = 0; c->diroff < c->dirlen; ++c->diroff) {
1019 			evbuffer_add_printf(out, "=> %s\n",
1020 			    c->dir[c->diroff]->d_name);
1021 			free(c->dir[c->diroff]);
1022 		}
1023 		free(c->dir);
1024 		c->dir = NULL;
1025 
1026 		c->type = REQUEST_DONE;
1027 
1028 		event_add(&c->bev->ev_write, NULL);
1029 		break;
1030 
1031 	case REQUEST_CGI:
1032 	case REQUEST_FCGI:
1033 		/*
1034 		 *  Here we depend on on the cgi script or fastcgi
1035 		 *  connection to provide data.
1036 		 */
1037 		break;
1038 
1039 	case REQUEST_DONE:
1040 		if (EVBUFFER_LENGTH(out) == 0)
1041 			client_close(c);
1042 		break;
1043 	}
1044 }
1045 
1046 static void
1047 client_error(struct bufferevent *bev, short error, void *d)
1048 {
1049 	struct client	*c = d;
1050 
1051 	c->type = REQUEST_DONE;
1052 
1053 	if (error & EVBUFFER_TIMEOUT) {
1054 		log_warn(c, "timeout reached, "
1055 		    "forcefully closing the connection");
1056 		if (c->code == 0)
1057 			start_reply(c, BAD_REQUEST, "timeout");
1058 		else
1059 			client_close(c);
1060 		return;
1061 	}
1062 
1063 	if (error & EVBUFFER_EOF) {
1064 		client_close(c);
1065 		return;
1066 	}
1067 
1068 	log_err(c, "unknown bufferevent error: %s", strerror(errno));
1069 	client_close(c);
1070 }
1071 
1072 void
1073 start_reply(struct client *c, int code, const char *meta)
1074 {
1075 	struct evbuffer	*evb = EVBUFFER_OUTPUT(c->bev);
1076 	const char	*lang;
1077 	int		 r, rr;
1078 
1079 	bufferevent_enable(c->bev, EVBUFFER_WRITE);
1080 
1081 	c->code = code;
1082 	c->meta = meta;
1083 
1084 	r = evbuffer_add_printf(evb, "%d %s", code, meta);
1085 	if (r == -1)
1086 		goto err;
1087 
1088 	/* 2 digit status + space + 1024 max reply */
1089 	if (r > 1027)
1090 		goto overflow;
1091 
1092 	if (c->type != REQUEST_CGI &&
1093 	    c->type != REQUEST_FCGI &&
1094 	    !strcmp(meta, "text/gemini") &&
1095 	    (lang = vhost_lang(c->host, c->iri.path)) != NULL) {
1096                 rr = evbuffer_add_printf(evb, ";lang=%s", lang);
1097 		if (rr == -1)
1098 			goto err;
1099 		if (r + rr > 1027)
1100 			goto overflow;
1101 	}
1102 
1103 	bufferevent_write(c->bev, "\r\n", 2);
1104 
1105 	if (!vhost_disable_log(c->host, c->iri.path))
1106 		log_request(c, EVBUFFER_DATA(evb), EVBUFFER_LENGTH(evb));
1107 
1108 	if (code != 20 && IS_INTERNAL_REQUEST(c->type))
1109 		c->type = REQUEST_DONE;
1110 
1111 	return;
1112 
1113 err:
1114 	log_err(c, "evbuffer_add_printf error: no memory");
1115 	evbuffer_drain(evb, EVBUFFER_LENGTH(evb));
1116 	client_close(c);
1117 	return;
1118 
1119 overflow:
1120 	log_warn(c, "reply header overflow");
1121 	evbuffer_drain(evb, EVBUFFER_LENGTH(evb));
1122 	start_reply(c, TEMP_FAILURE, "internal error");
1123 }
1124 
1125 static void
1126 client_close_ev(int fd, short event, void *d)
1127 {
1128 	struct client	*c = d;
1129 
1130 	switch (tls_close(c->ctx)) {
1131 	case TLS_WANT_POLLIN:
1132 		event_once(c->fd, EV_READ, client_close_ev, c, NULL);
1133 		break;
1134 	case TLS_WANT_POLLOUT:
1135 		event_once(c->fd, EV_WRITE, client_close_ev, c, NULL);
1136 		break;
1137 	}
1138 
1139 	connected_clients--;
1140 
1141 	free(c->req);
1142 
1143 	tls_free(c->ctx);
1144 	c->ctx = NULL;
1145 
1146 	free(c->header);
1147 
1148 	if (c->pfd != -1)
1149 		close(c->pfd);
1150 
1151 	if (c->dir != NULL)
1152 		free(c->dir);
1153 
1154 	close(c->fd);
1155 	c->fd = -1;
1156 }
1157 
1158 void
1159 client_close(struct client *c)
1160 {
1161 	/*
1162 	 * We may end up calling client_close in various situations
1163 	 * and for the most unexpected reasons.  Therefore, we need to
1164 	 * ensure that everything is properly released once we reach
1165 	 * this point.
1166 	 */
1167 
1168 	if (c->cgibev != NULL) {
1169 		bufferevent_disable(c->cgibev, EVBUFFER_READ|EVBUFFER_WRITE);
1170 		bufferevent_free(c->cgibev);
1171 		c->cgibev = NULL;
1172 		close(c->pfd);
1173 		c->pfd = -1;
1174 	}
1175 
1176 	bufferevent_disable(c->bev, EVBUFFER_READ|EVBUFFER_WRITE);
1177 	bufferevent_free(c->bev);
1178 	c->bev = NULL;
1179 
1180 	client_close_ev(c->fd, 0, c);
1181 }
1182 
1183 static void
1184 cgi_read(struct bufferevent *bev, void *d)
1185 {
1186 	struct client	*client = d;
1187 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
1188 	char		*header;
1189 	size_t		 len;
1190 	int		 code;
1191 
1192 	/* intercept the header */
1193 	if (client->code == 0) {
1194 		header = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
1195 		if (header == NULL) {
1196 			/* max reply + \r\n */
1197 			if (EVBUFFER_LENGTH(src) > 1026) {
1198 				log_warn(client, "CGI script is trying to "
1199 				    "send a header too long.");
1200 				cgi_error(bev, EVBUFFER_READ, client);
1201 			}
1202 
1203 			/* wait a bit */
1204 			return;
1205 		}
1206 
1207 		if (len < 3 || len > 1029 ||
1208 		    !isdigit(header[0]) ||
1209 		    !isdigit(header[1]) ||
1210 		    !isspace(header[2])) {
1211 			free(header);
1212 			log_warn(client, "CGI script is trying to send a "
1213 			    "malformed header");
1214 			cgi_error(bev, EVBUFFER_READ, client);
1215 			return;
1216 		}
1217 
1218 		client->header = header;
1219 		code = (header[0] - '0') * 10 + (header[1] - '0');
1220 
1221 		if (code < 10 || code >= 70) {
1222 			log_warn(client, "CGI script is trying to send an "
1223 			    "invalid reply code (%d)", code);
1224 			cgi_error(bev, EVBUFFER_READ, client);
1225 			return;
1226 		}
1227 
1228 		start_reply(client, code, header + 3);
1229 
1230 		if (client->code < 20 || client->code > 29) {
1231 			cgi_error(client->cgibev, EVBUFFER_EOF, client);
1232 			return;
1233 		}
1234 	}
1235 
1236 	bufferevent_write_buffer(client->bev, src);
1237 }
1238 
1239 static void
1240 cgi_write(struct bufferevent *bev, void *d)
1241 {
1242 	/*
1243 	 * Never called.  We don't send data to a CGI script.
1244 	 */
1245 	abort();
1246 }
1247 
1248 static void
1249 cgi_error(struct bufferevent *bev, short error, void *d)
1250 {
1251 	struct client	*client = d;
1252 
1253 	if (error & EVBUFFER_ERROR)
1254 		log_err(client, "%s: evbuffer error (%x): %s",
1255 		    __func__, error, strerror(errno));
1256 
1257 	bufferevent_disable(bev, EVBUFFER_READ|EVBUFFER_WRITE);
1258 	bufferevent_free(bev);
1259 	client->cgibev = NULL;
1260 
1261 	close(client->pfd);
1262 	client->pfd = -1;
1263 
1264 	client->type = REQUEST_DONE;
1265 	if (client->code != 0)
1266 		client_write(client->bev, client);
1267 	else
1268 		start_reply(client, CGI_ERROR, "CGI error");
1269 }
1270 
1271 static void
1272 do_accept(int sock, short et, void *d)
1273 {
1274 	struct client *c;
1275 	struct sockaddr_storage addr;
1276 	struct sockaddr *saddr;
1277 	socklen_t len;
1278 	int i, fd;
1279 
1280 	(void)et;
1281 
1282 	saddr = (struct sockaddr*)&addr;
1283 	len = sizeof(addr);
1284 	if ((fd = accept(sock, saddr, &len)) == -1) {
1285 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1286 			return;
1287 		fatal("accept: %s", strerror(errno));
1288 	}
1289 
1290 	mark_nonblock(fd);
1291 
1292 	for (i = 0; i < MAX_USERS; ++i) {
1293 		c = &clients[i];
1294 		if (c->fd == -1) {
1295 			memset(c, 0, sizeof(*c));
1296 			c->id = i;
1297 			if (tls_accept_socket(ctx, &c->ctx, fd) == -1)
1298 				break; /* goodbye fd! */
1299 
1300 			c->fd = fd;
1301 			c->pfd = -1;
1302 			c->dir = NULL;
1303 			c->addr = addr;
1304 
1305 			event_once(c->fd, EV_READ|EV_WRITE, handle_handshake,
1306 			    c, NULL);
1307 
1308 			connected_clients++;
1309 			return;
1310 		}
1311 	}
1312 
1313 	close(fd);
1314 }
1315 
1316 static struct client *
1317 client_by_id(int id)
1318 {
1319 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1320 		fatal("in client_by_id: invalid id %d", id);
1321 	return &clients[id];
1322 }
1323 
1324 struct client *
1325 try_client_by_id(int id)
1326 {
1327 	if ((size_t)id > sizeof(clients)/sizeof(clients[0]))
1328                 return NULL;
1329 	return &clients[id];
1330 }
1331 
1332 static void
1333 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1334 {
1335 	struct client *c;
1336 
1337 	c = client_by_id(imsg->hdr.peerid);
1338 
1339 	if ((c->pfd = imsg->fd) == -1) {
1340 		start_reply(c, TEMP_FAILURE, "internal server error");
1341 		return;
1342 	}
1343 
1344 	c->type = REQUEST_CGI;
1345 
1346 	c->cgibev = bufferevent_new(c->pfd, cgi_read, cgi_write,
1347 	    cgi_error, c);
1348 
1349 	bufferevent_enable(c->cgibev, EV_READ);
1350 }
1351 
1352 static void
1353 handle_imsg_fcgi_fd(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1354 {
1355 	struct client	*c;
1356 	int		 id;
1357 
1358 	id = imsg->hdr.peerid;
1359 
1360 	if ((c = try_client_by_id(id)) == NULL) {
1361 		if (imsg->fd != -1)
1362 			close(imsg->fd);
1363 		return;
1364 	}
1365 
1366 	if ((c->pfd = imsg->fd) == -1) {
1367 		start_reply(c, CGI_ERROR, "CGI error");
1368 		return;
1369 	}
1370 
1371 	mark_nonblock(c->pfd);
1372 
1373 	c->cgibev = bufferevent_new(c->pfd, fcgi_read, fcgi_write,
1374 	    fcgi_error, c);
1375 	if (c->cgibev == NULL) {
1376 		start_reply(c, TEMP_FAILURE, "internal server error");
1377 		return;
1378 	}
1379 
1380 	bufferevent_enable(c->cgibev, EV_READ|EV_WRITE);
1381 	fcgi_req(c);
1382 }
1383 
1384 static void
1385 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1386 {
1387 	(void)imsg;
1388 	(void)len;
1389 
1390 	/*
1391 	 * don't call event_loopbreak since we want to finish to
1392 	 * handle the ongoing connections.
1393 	 */
1394 
1395 	shutting_down = 1;
1396 
1397 	event_del(&e4);
1398 	if (has_ipv6)
1399 		event_del(&e6);
1400 	if (has_siginfo)
1401 		signal_del(&siginfo);
1402 	event_del(&imsgev);
1403 	signal_del(&sigusr2);
1404 }
1405 
1406 static void
1407 handle_dispatch_imsg(int fd, short ev, void *d)
1408 {
1409 	struct imsgbuf *ibuf = d;
1410 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1411 }
1412 
1413 static void
1414 handle_siginfo(int fd, short ev, void *d)
1415 {
1416 	(void)fd;
1417 	(void)ev;
1418 	(void)d;
1419 
1420 	log_info(NULL, "%d connected clients", connected_clients);
1421 }
1422 
1423 void
1424 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1425 {
1426 	size_t i;
1427 
1428 	ctx = ctx_;
1429 
1430 	event_init();
1431 
1432 	memset(&clients, 0, sizeof(clients));
1433 	for (i = 0; i < MAX_USERS; ++i)
1434 		clients[i].fd = -1;
1435 
1436 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1437 	event_add(&e4, NULL);
1438 
1439 	if (sock6 != -1) {
1440 		has_ipv6 = 1;
1441 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1442 		event_add(&e6, NULL);
1443 	}
1444 
1445 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1446 	event_add(&imsgev, NULL);
1447 
1448 #ifdef SIGINFO
1449 	has_siginfo = 1;
1450 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1451 	signal_add(&siginfo, NULL);
1452 #endif
1453 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1454 	signal_add(&sigusr2, NULL);
1455 
1456 	sandbox_server_process();
1457 	event_dispatch();
1458 	_exit(0);
1459 }