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 static struct tls	*ctx;
35 
36 static struct event e4, e6, imsgev, siginfo, sigusr2;
37 static int has_ipv6, has_siginfo;
38 
39 int connected_clients;
40 
41 static inline int matches(const char*, const char*);
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_fastcgi(struct client*);
51 static int	 apply_require_ca(struct client*);
52 static size_t	 host_nth(struct vhost*);
53 static void	 start_cgi(const char*, const char*, struct client*);
54 static void	 open_dir(struct client*);
55 static void	 redirect_canonical_dir(struct client*);
56 
57 static void	 client_tls_readcb(int, short, void *);
58 static void	 client_tls_writecb(int, short, void *);
59 
60 static void	 client_read(struct bufferevent *, void *);
61 void		 client_write(struct bufferevent *, void *);
62 static void	 client_error(struct bufferevent *, short, void *);
63 
64 static void	 client_close_ev(int, short, void *);
65 
66 static void	 cgi_read(struct bufferevent *, void *);
67 static void	 cgi_write(struct bufferevent *, void *);
68 static void	 cgi_error(struct bufferevent *, short, void *);
69 
70 static void	 do_accept(int, short, void*);
71 static struct client *client_by_id(int);
72 
73 static void	 handle_imsg_cgi_res(struct imsgbuf*, struct imsg*, size_t);
74 static void	 handle_imsg_fcgi_fd(struct imsgbuf*, struct imsg*, size_t);
75 static void	 handle_imsg_quit(struct imsgbuf*, struct imsg*, size_t);
76 static void	 handle_dispatch_imsg(int, short, void *);
77 static void	 handle_siginfo(int, short, void*);
78 
79 static imsg_handlerfn *handlers[] = {
80 	[IMSG_QUIT] = handle_imsg_quit,
81 	[IMSG_CGI_RES] = handle_imsg_cgi_res,
82 	[IMSG_FCGI_FD] = handle_imsg_fcgi_fd,
83 };
84 
85 static uint32_t server_client_id;
86 
87 struct client_tree_id clients;
88 
89 static inline int
90 matches(const char *pattern, const char *path)
91 {
92 	if (*path == '/')
93 		path++;
94 	return !fnmatch(pattern, path, 0);
95 }
96 
97 const char *
98 vhost_lang(struct vhost *v, const char *path)
99 {
100 	struct location *loc;
101 
102 	if (v == NULL || path == NULL)
103 		return NULL;
104 
105 	loc = TAILQ_FIRST(&v->locations);
106 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
107 		if (loc->lang != NULL) {
108 			if (matches(loc->match, path))
109 				return loc->lang;
110 		}
111 	}
112 
113 	return TAILQ_FIRST(&v->locations)->lang;
114 }
115 
116 const char *
117 vhost_default_mime(struct vhost *v, const char *path)
118 {
119 	struct location *loc;
120 	const char *default_mime = "application/octet-stream";
121 
122 	if (v == NULL || path == NULL)
123 		return default_mime;
124 
125 	loc = TAILQ_FIRST(&v->locations);
126 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
127 		if (loc->default_mime != NULL) {
128 			if (matches(loc->match, path))
129 				return loc->default_mime;
130 		}
131 	}
132 
133 	loc = TAILQ_FIRST(&v->locations);
134 	if (loc->default_mime != NULL)
135 		return loc->default_mime;
136 	return default_mime;
137 }
138 
139 const char *
140 vhost_index(struct vhost *v, const char *path)
141 {
142 	struct location *loc;
143 	const char *index = "index.gmi";
144 
145 	if (v == NULL || path == NULL)
146 		return index;
147 
148 	loc = TAILQ_FIRST(&v->locations);
149 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
150 		if (loc->index != NULL) {
151 			if (matches(loc->match, path))
152 				return loc->index;
153 		}
154 	}
155 
156 	loc = TAILQ_FIRST(&v->locations);
157 	if (loc->index != NULL)
158 		return loc->index;
159 	return index;
160 }
161 
162 int
163 vhost_auto_index(struct vhost *v, const char *path)
164 {
165 	struct location *loc;
166 
167 	if (v == NULL || path == NULL)
168 		return 0;
169 
170 	loc = TAILQ_FIRST(&v->locations);
171 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
172 		if (loc->auto_index != 0) {
173 			if (matches(loc->match, path))
174 				return loc->auto_index == 1;
175 		}
176 	}
177 
178 	loc = TAILQ_FIRST(&v->locations);
179 	return loc->auto_index == 1;
180 }
181 
182 int
183 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
184 {
185 	struct location *loc;
186 
187 	if (v == NULL || path == NULL)
188 		return 0;
189 
190 	loc = TAILQ_FIRST(&v->locations);
191 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
192 		if (loc->block_code != 0) {
193 			if (matches(loc->match, path)) {
194 				*code = loc->block_code;
195 				*fmt = loc->block_fmt;
196 				return 1;
197 			}
198 		}
199 	}
200 
201 	loc = TAILQ_FIRST(&v->locations);
202 	*code = loc->block_code;
203 	*fmt = loc->block_fmt;
204 	return loc->block_code != 0;
205 }
206 
207 int
208 vhost_fastcgi(struct vhost *v, const char *path)
209 {
210 	struct location *loc;
211 
212 	if (v == NULL || path == NULL)
213 		return -1;
214 
215 	loc = TAILQ_FIRST(&v->locations);
216 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
217 		if (loc->fcgi != -1)
218 			if (matches(loc->match, path))
219 				return loc->fcgi;
220 	}
221 
222 	loc = TAILQ_FIRST(&v->locations);
223 	return loc->fcgi;
224 }
225 
226 int
227 vhost_dirfd(struct vhost *v, const char *path, size_t *retloc)
228 {
229 	struct location *loc;
230 	size_t		 l = 0;
231 
232 	if (v == NULL || path == NULL)
233 		return -1;
234 
235 	loc = TAILQ_FIRST(&v->locations);
236 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
237 		l++;
238 		if (loc->dirfd != -1)
239 			if (matches(loc->match, path)) {
240 				*retloc = l;
241 				return loc->dirfd;
242 			}
243 	}
244 
245 	*retloc = 0;
246 	loc = TAILQ_FIRST(&v->locations);
247 	return loc->dirfd;
248 }
249 
250 int
251 vhost_strip(struct vhost *v, const char *path)
252 {
253 	struct location *loc;
254 
255 	if (v == NULL || path == NULL)
256 		return 0;
257 
258 	loc = TAILQ_FIRST(&v->locations);
259 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
260 		if (loc->strip != 0) {
261 			if (matches(loc->match, path))
262 				return loc->strip;
263 		}
264 	}
265 
266 	loc = TAILQ_FIRST(&v->locations);
267 	return loc->strip;
268 }
269 
270 X509_STORE *
271 vhost_require_ca(struct vhost *v, const char *path)
272 {
273 	struct location *loc;
274 
275 	if (v == NULL || path == NULL)
276 		return NULL;
277 
278 	loc = TAILQ_FIRST(&v->locations);
279 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
280 		if (loc->reqca != NULL) {
281 			if (matches(loc->match, path))
282 				return loc->reqca;
283 		}
284 	}
285 
286 	loc = TAILQ_FIRST(&v->locations);
287 	return loc->reqca;
288 }
289 
290 int
291 vhost_disable_log(struct vhost *v, const char *path)
292 {
293 	struct location *loc;
294 
295 	if (v == NULL || path == NULL)
296 		return 0;
297 
298 	loc = TAILQ_FIRST(&v->locations);
299 	while ((loc = TAILQ_NEXT(loc, locations)) != NULL) {
300 		if (loc->disable_log && matches(loc->match, path))
301 				return 1;
302 	}
303 
304 	loc = TAILQ_FIRST(&v->locations);
305 	return loc->disable_log;
306 }
307 
308 static int
309 check_path(struct client *c, const char *path, int *fd)
310 {
311 	struct stat sb;
312 	const char *p;
313 	int dirfd, strip;
314 
315 	assert(path != NULL);
316 
317 	/*
318 	 * in send_dir we add an initial / (to be redirect-friendly),
319 	 * but here we want to skip it
320 	 */
321 	if (*path == '/')
322 		path++;
323 
324 	strip = vhost_strip(c->host, path);
325 	p = strip_path(path, strip);
326 
327 	if (*p == '/')
328 		p = p+1;
329 	if (*p == '\0')
330 		p = ".";
331 
332 	dirfd = vhost_dirfd(c->host, path, &c->loc);
333 	log_debug(c, "check_path: strip=%d path=%s original=%s",
334 	    strip, p, path);
335 	if (*fd == -1 && (*fd = openat(dirfd, p, O_RDONLY)) == -1)
336 		return FILE_MISSING;
337 
338 	if (fstat(*fd, &sb) == -1) {
339 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
340 		return FILE_MISSING;
341 	}
342 
343 	if (S_ISDIR(sb.st_mode))
344 		return FILE_DIRECTORY;
345 
346 	if (sb.st_mode & S_IXUSR)
347 		return FILE_EXECUTABLE;
348 
349 	return FILE_EXISTS;
350 }
351 
352 static void
353 open_file(struct client *c)
354 {
355 	switch (check_path(c, c->iri.path, &c->pfd)) {
356 	case FILE_EXECUTABLE:
357 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
358 			start_cgi(c->iri.path, "", c);
359 			return;
360 		}
361 
362 		/* fallthrough */
363 
364 	case FILE_EXISTS:
365 		c->type = REQUEST_FILE;
366 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
367 		return;
368 
369 	case FILE_DIRECTORY:
370 		open_dir(c);
371 		return;
372 
373 	case FILE_MISSING:
374 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
375 			check_for_cgi(c);
376 			return;
377 		}
378 		start_reply(c, NOT_FOUND, "not found");
379 		return;
380 
381 	default:
382 		/* unreachable */
383 		abort();
384 	}
385 }
386 
387 /*
388  * the inverse of this algorithm, i.e. starting from the start of the
389  * path + strlen(cgi), and checking if each component, should be
390  * faster.  But it's tedious to write.  This does the opposite: starts
391  * from the end and strip one component at a time, until either an
392  * executable is found or we emptied the path.
393  */
394 static void
395 check_for_cgi(struct client *c)
396 {
397 	char path[PATH_MAX];
398 	char *end;
399 
400 	strlcpy(path, c->iri.path, sizeof(path));
401 	end = strchr(path, '\0');
402 
403 	while (end > path) {
404 		/*
405 		 * go up one level.  UNIX paths are simple and POSIX
406 		 * dirname, with its ambiguities on if the given
407 		 * pointer is changed or not, gives me headaches.
408 		 */
409 		while (*end != '/' && end > path)
410 			end--;
411 
412 		if (end == path)
413 			break;
414 
415 		*end = '\0';
416 
417 		switch (check_path(c, path, &c->pfd)) {
418 		case FILE_EXECUTABLE:
419 			start_cgi(path, end+1, c);
420 			return;
421 		case FILE_MISSING:
422 			break;
423 		default:
424 			goto err;
425 		}
426 
427 		*end = '/';
428 		end--;
429 	}
430 
431 err:
432 	start_reply(c, NOT_FOUND, "not found");
433 	return;
434 }
435 
436 void
437 mark_nonblock(int fd)
438 {
439 	int flags;
440 
441 	if ((flags = fcntl(fd, F_GETFL)) == -1)
442 		fatal("fcntl(F_GETFL): %s", strerror(errno));
443 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
444 		fatal("fcntl(F_SETFL): %s", strerror(errno));
445 }
446 
447 static void
448 handle_handshake(int fd, short ev, void *d)
449 {
450 	struct client *c = d;
451 	struct vhost *h;
452 	struct alist *a;
453 	const char *servname;
454 	const char *parse_err = "unknown error";
455 
456 	switch (tls_handshake(c->ctx)) {
457 	case 0:  /* success */
458 	case -1: /* already handshaked */
459 		break;
460 	case TLS_WANT_POLLIN:
461 		event_once(c->fd, EV_READ, handle_handshake, c, NULL);
462 		return;
463 	case TLS_WANT_POLLOUT:
464 		event_once(c->fd, EV_WRITE, handle_handshake, c, NULL);
465 		return;
466 	default:
467 		/* unreachable */
468 		abort();
469 	}
470 
471 	if ((servname = tls_conn_servername(c->ctx)) == NULL) {
472 		log_debug(c, "handshake: missing SNI");
473 		goto err;
474 	}
475 
476 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
477 		log_info(c, "puny_decode: %s", parse_err);
478 		goto err;
479 	}
480 
481 	TAILQ_FOREACH(h, &hosts, vhosts) {
482 		if (matches(h->domain, c->domain))
483 			goto found;
484 		TAILQ_FOREACH(a, &h->aliases, aliases) {
485 			if (matches(a->alias, c->domain))
486 				goto found;
487 		}
488 	}
489 
490 found:
491 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
492 	    servname != NULL ? servname : "(null)",
493 	    c->domain,
494 	    h != NULL ? h->domain : "(null)");
495 
496 	if (h != NULL) {
497 		c->host = h;
498 
499 		c->bev = bufferevent_new(fd, client_read, client_write,
500 		    client_error, c);
501 		if (c->bev == NULL)
502 			fatal("%s: failed to allocate client buffer: %s",
503 			    __func__, strerror(errno));
504 
505 		event_set(&c->bev->ev_read, c->fd, EV_READ,
506 		    client_tls_readcb, c->bev);
507 		event_set(&c->bev->ev_write, c->fd, EV_WRITE,
508 		    client_tls_writecb, c->bev);
509 
510 #if HAVE_LIBEVENT2
511 		evbuffer_unfreeze(c->bev->input, 0);
512 		evbuffer_unfreeze(c->bev->output, 1);
513 #endif
514 
515 		bufferevent_enable(c->bev, EV_READ);
516 
517 		return;
518 	}
519 
520 err:
521 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
522 }
523 
524 static const char *
525 strip_path(const char *path, int strip)
526 {
527 	char *t;
528 
529 	while (strip > 0) {
530 		if ((t = strchr(path, '/')) == NULL) {
531 			path = strchr(path, '\0');
532 			break;
533 		}
534 		path = t;
535 		strip--;
536 	}
537 
538 	return path;
539 }
540 
541 static void
542 fmt_sbuf(const char *fmt, struct client *c, const char *path)
543 {
544 	size_t i;
545         char buf[32];
546 
547 	memset(buf, 0, sizeof(buf));
548 	for (i = 0; *fmt; ++fmt) {
549 		if (i == sizeof(buf)-1 || *fmt == '%') {
550 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
551 			memset(buf, 0, sizeof(buf));
552 			i = 0;
553 		}
554 
555 		if (*fmt != '%') {
556 			buf[i++] = *fmt;
557 			continue;
558 		}
559 
560 		switch (*++fmt) {
561 		case '%':
562 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
563 			break;
564 		case 'p':
565 			if (*path != '/')
566 				strlcat(c->sbuf, "/", sizeof(c->sbuf));
567 			strlcat(c->sbuf, path, sizeof(c->sbuf));
568 			break;
569 		case 'q':
570 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
571 			break;
572 		case 'P':
573 			snprintf(buf, sizeof(buf), "%d", conf.port);
574 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
575 			memset(buf, 0, sizeof(buf));
576 			break;
577 		case 'N':
578 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
579 			break;
580 		default:
581 			fatal("%s: unknown fmt specifier %c",
582 			    __func__, *fmt);
583 		}
584 	}
585 
586 	if (i != 0)
587 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
588 }
589 
590 /* 1 if a matching `block return' (and apply it), 0 otherwise */
591 static int
592 apply_block_return(struct client *c)
593 {
594 	const char *fmt, *path;
595 	int code;
596 
597 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
598 		return 0;
599 
600 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
601 	fmt_sbuf(fmt, c, path);
602 
603 	start_reply(c, code, c->sbuf);
604 	return 1;
605 }
606 
607 /* 1 if matching `fcgi' (and apply it), 0 otherwise */
608 static int
609 apply_fastcgi(struct client *c)
610 {
611 	int		 id;
612 	struct fcgi	*f;
613 
614 	if ((id = vhost_fastcgi(c->host, c->iri.path)) == -1)
615 		return 0;
616 
617 	f = &fcgi[id];
618 
619 	log_debug(c, "opening fastcgi connection for (%s,%s,%s)",
620 	    f->path, f->port, f->prog);
621 
622 	imsg_compose(&exibuf, IMSG_FCGI_REQ, c->id, 0, -1,
623 	    &id, sizeof(id));
624 	imsg_flush(&exibuf);
625 	return 1;
626 }
627 
628 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
629 static int
630 apply_require_ca(struct client *c)
631 {
632 	X509_STORE	*store;
633 	const uint8_t	*cert;
634 	size_t		 len;
635 
636 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
637 		return 0;
638 
639 	if (!tls_peer_cert_provided(c->ctx)) {
640 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
641 		return 1;
642 	}
643 
644 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
645 	if (!validate_against_ca(store, cert, len)) {
646 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
647 		return 1;
648 	}
649 
650 	return 0;
651 }
652 
653 static size_t
654 host_nth(struct vhost *h)
655 {
656 	struct vhost	*v;
657 	size_t		 i = 0;
658 
659 	TAILQ_FOREACH(v, &hosts, vhosts) {
660 		if (v == h)
661 			return i;
662 		i++;
663 	}
664 
665 	abort();
666 }
667 
668 static void
669 start_cgi(const char *spath, const char *relpath, struct client *c)
670 {
671 	char addr[NI_MAXHOST];
672 	const char *t;
673 	struct cgireq req;
674 	int e;
675 
676 	c->type = REQUEST_CGI;
677 
678 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
679 	    addr, sizeof(addr),
680 	    NULL, 0,
681 	    NI_NUMERICHOST);
682 	if (e != 0)
683 		fatal("getnameinfo failed");
684 
685 	memset(&req, 0, sizeof(req));
686 
687 	memcpy(req.buf, c->req, sizeof(req.buf));
688 
689 	req.iri_schema_off = c->iri.schema - c->req;
690 	req.iri_host_off = c->iri.host - c->req;
691 	req.iri_port_off = c->iri.port - c->req;
692 	req.iri_path_off = c->iri.path - c->req;
693 	req.iri_query_off = c->iri.query - c->req;
694 	req.iri_fragment_off = c->iri.fragment - c->req;
695 
696 	req.iri_portno = c->iri.port_no;
697 
698 	strlcpy(req.spath, spath, sizeof(req.spath));
699 	strlcpy(req.relpath, relpath, sizeof(req.relpath));
700 	strlcpy(req.addr, addr, sizeof(req.addr));
701 
702 	if ((t = tls_peer_cert_subject(c->ctx)) != NULL)
703 		strlcpy(req.subject, t, sizeof(req.subject));
704 	if ((t = tls_peer_cert_issuer(c->ctx)) != NULL)
705 		strlcpy(req.issuer, t, sizeof(req.issuer));
706 	if ((t = tls_peer_cert_hash(c->ctx)) != NULL)
707 		strlcpy(req.hash, t, sizeof(req.hash));
708 	if ((t = tls_conn_version(c->ctx)) != NULL)
709 		strlcpy(req.version, t, sizeof(req.version));
710 	if ((t = tls_conn_cipher(c->ctx)) != NULL)
711 		strlcpy(req.cipher, t, sizeof(req.cipher));
712 
713 	req.cipher_strength = tls_conn_cipher_strength(c->ctx);
714 	req.notbefore = tls_peer_cert_notbefore(c->ctx);
715 	req.notafter = tls_peer_cert_notafter(c->ctx);
716 
717 	req.host_off = host_nth(c->host);
718 	req.loc_off = c->loc;
719 
720 	imsg_compose(&exibuf, IMSG_CGI_REQ, c->id, 0, -1, &req, sizeof(req));
721 	imsg_flush(&exibuf);
722 
723 	close(c->pfd);
724 }
725 
726 static void
727 open_dir(struct client *c)
728 {
729 	size_t len;
730 	int dirfd, root;
731 	char *before_file;
732 
733 	root = !strcmp(c->iri.path, "/") || *c->iri.path == '\0';
734 
735 	len = strlen(c->iri.path);
736 	if (len > 0 && !ends_with(c->iri.path, "/")) {
737 		redirect_canonical_dir(c);
738 		return;
739 	}
740 
741 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
742 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
743 	if (!ends_with(c->sbuf, "/"))
744 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
745 	before_file = strchr(c->sbuf, '\0');
746 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
747 	    sizeof(c->sbuf));
748 	if (len >= sizeof(c->sbuf)) {
749 		start_reply(c, TEMP_FAILURE, "internal server error");
750 		return;
751 	}
752 
753 	c->iri.path = c->sbuf;
754 
755 	/* close later unless we have to generate the dir listing */
756 	dirfd = c->pfd;
757 	c->pfd = -1;
758 
759 	switch (check_path(c, c->iri.path, &c->pfd)) {
760 	case FILE_EXECUTABLE:
761 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
762 			start_cgi(c->iri.path, "", c);
763 			break;
764 		}
765 
766 		/* fallthrough */
767 
768 	case FILE_EXISTS:
769 		c->type = REQUEST_FILE;
770 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
771 		break;
772 
773 	case FILE_DIRECTORY:
774 		start_reply(c, TEMP_REDIRECT, c->sbuf);
775 		break;
776 
777 	case FILE_MISSING:
778 		*before_file = '\0';
779 
780 		if (!vhost_auto_index(c->host, c->iri.path)) {
781 			start_reply(c, NOT_FOUND, "not found");
782 			break;
783 		}
784 
785 		c->type = REQUEST_DIR;
786 
787 		c->dirlen = scandir_fd(dirfd, &c->dir,
788 		    root ? select_non_dotdot : select_non_dot,
789 		    alphasort);
790 		if (c->dirlen == -1) {
791 			log_err(c, "scandir_fd(%d) (vhost:%s) %s: %s",
792 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
793 			start_reply(c, TEMP_FAILURE, "internal server error");
794 			return;
795 		}
796 		c->diroff = 0;
797 		c->off = 0;
798 
799                 start_reply(c, SUCCESS, "text/gemini");
800 		evbuffer_add_printf(EVBUFFER_OUTPUT(c->bev),
801 		    "# Index of %s\n\n", c->iri.path);
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 client_tls_readcb(int fd, short event, void *d)
831 {
832 	struct bufferevent	*bufev = d;
833 	struct client		*client = bufev->cbarg;
834 	ssize_t			 ret;
835 	size_t			 len;
836 	int			 what = EVBUFFER_READ;
837 	int			 howmuch = IBUF_READ_SIZE;
838 	char			 buf[IBUF_READ_SIZE];
839 
840 	if (event == EV_TIMEOUT) {
841 		what |= EVBUFFER_TIMEOUT;
842 		goto err;
843 	}
844 
845 	if (bufev->wm_read.high != 0)
846 		howmuch = MIN(sizeof(buf), bufev->wm_read.high);
847 
848 	switch (ret = tls_read(client->ctx, buf, howmuch)) {
849 	case TLS_WANT_POLLIN:
850 	case TLS_WANT_POLLOUT:
851 		goto retry;
852 	case -1:
853 		what |= EVBUFFER_ERROR;
854 		goto err;
855 	}
856 	len = ret;
857 
858 	if (len == 0) {
859 		what |= EVBUFFER_EOF;
860 		goto err;
861 	}
862 
863 	if (evbuffer_add(bufev->input, buf, len) == -1) {
864 		what |= EVBUFFER_ERROR;
865 		goto err;
866 	}
867 
868 	event_add(&bufev->ev_read, NULL);
869 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
870 		return;
871 	if (bufev->wm_read.high != 0 && len > bufev->wm_read.high) {
872 		/*
873 		 * here we could implement a read pressure policy.
874 		 */
875 	}
876 
877 	if (bufev->readcb != NULL)
878 		(*bufev->readcb)(bufev, bufev->cbarg);
879 
880 	return;
881 
882 retry:
883 	event_add(&bufev->ev_read, NULL);
884 	return;
885 
886 err:
887 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
888 }
889 
890 static void
891 client_tls_writecb(int fd, short event, void *d)
892 {
893 	struct bufferevent	*bufev = d;
894 	struct client		*client = bufev->cbarg;
895 	ssize_t			 ret;
896 	size_t			 len;
897 	short			 what = EVBUFFER_WRITE;
898 
899 	if (event == EV_TIMEOUT) {
900 		what |= EVBUFFER_TIMEOUT;
901 		goto err;
902 	}
903 
904 	if (EVBUFFER_LENGTH(bufev->output) != 0) {
905 		ret = tls_write(client->ctx,
906 		    EVBUFFER_DATA(bufev->output),
907 		    EVBUFFER_LENGTH(bufev->output));
908 		switch (ret) {
909 		case TLS_WANT_POLLIN:
910 		case TLS_WANT_POLLOUT:
911 			goto retry;
912 		case -1:
913 			what |= EVBUFFER_ERROR;
914 			goto err;
915 		}
916 		len = ret;
917 		evbuffer_drain(bufev->output, len);
918 	}
919 
920 	if (EVBUFFER_LENGTH(bufev->output) != 0)
921 		event_add(&bufev->ev_write, NULL);
922 
923 	if (bufev->writecb != NULL &&
924 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
925 		(*bufev->writecb)(bufev, bufev->cbarg);
926 	return;
927 
928 retry:
929 	event_add(&bufev->ev_write, NULL);
930 	return;
931 err:
932 	log_err(client, "tls error: %s", tls_error(client->ctx));
933 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
934 }
935 
936 static void
937 client_read(struct bufferevent *bev, void *d)
938 {
939 	struct client	*c = d;
940 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
941 	const char	*parse_err = "invalid request";
942 	char		 decoded[DOMAIN_NAME_LEN];
943 	size_t		 len;
944 
945 	bufferevent_disable(bev, EVBUFFER_READ);
946 
947 	/* max url len + \r\n */
948 	if (EVBUFFER_LENGTH(src) > 1024 + 2) {
949 		log_err(c, "too much data received");
950 		start_reply(c, BAD_REQUEST, "bad request");
951 		return;
952 	}
953 
954 	c->req = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
955 	if (c->req == NULL) {
956 		/* not enough data yet. */
957 		bufferevent_enable(bev, EVBUFFER_READ);
958 		return;
959 	}
960 
961 	if (!parse_iri(c->req, &c->iri, &parse_err) ||
962 	    !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
963 		log_err(c, "IRI parse error: %s", parse_err);
964 		start_reply(c, BAD_REQUEST, "bad request");
965 		return;
966 	}
967 
968 	if (c->iri.port_no != conf.port ||
969 	    strcmp(c->iri.schema, "gemini") ||
970 	    strcmp(decoded, c->domain)) {
971 		start_reply(c, PROXY_REFUSED, "won't proxy request");
972 		return;
973 	}
974 
975 	if (apply_require_ca(c) ||
976 	    apply_block_return(c)||
977 	    apply_fastcgi(c))
978 		return;
979 
980 	if (c->host->entrypoint != NULL) {
981 		c->loc = 0;
982 		start_cgi(c->host->entrypoint, c->iri.path, c);
983 		return;
984 	}
985 
986 	open_file(c);
987 }
988 
989 void
990 client_write(struct bufferevent *bev, void *d)
991 {
992 	struct client	*c = d;
993 	struct evbuffer	*out = EVBUFFER_OUTPUT(bev);
994 	char		 buf[BUFSIZ];
995 	ssize_t		 r;
996 
997 	switch (c->type) {
998 	case REQUEST_UNDECIDED:
999 		/*
1000 		 * Ignore spurious calls when we still don't have idea
1001 		 * what to do with the request.
1002 		 */
1003 		break;
1004 
1005 	case REQUEST_FILE:
1006 		if ((r = read(c->pfd, buf, sizeof(buf))) == -1) {
1007 			log_warn(c, "read: %s", strerror(errno));
1008 			client_error(bev, EVBUFFER_ERROR, c);
1009 			return;
1010 		} else if (r == 0) {
1011 			client_close(c);
1012 			return;
1013 		} else if (r != sizeof(buf))
1014 			c->type = REQUEST_DONE;
1015 		bufferevent_write(bev, buf, r);
1016 		break;
1017 
1018 	case REQUEST_DIR:
1019 		/* TODO: handle big big directories better */
1020 		for (c->diroff = 0; c->diroff < c->dirlen; ++c->diroff) {
1021 			evbuffer_add_printf(out, "=> %s\n",
1022 			    c->dir[c->diroff]->d_name);
1023 			free(c->dir[c->diroff]);
1024 		}
1025 		free(c->dir);
1026 		c->dir = NULL;
1027 
1028 		c->type = REQUEST_DONE;
1029 
1030 		event_add(&c->bev->ev_write, NULL);
1031 		break;
1032 
1033 	case REQUEST_CGI:
1034 	case REQUEST_FCGI:
1035 		/*
1036 		 *  Here we depend on on the cgi script or fastcgi
1037 		 *  connection to provide data.
1038 		 */
1039 		break;
1040 
1041 	case REQUEST_DONE:
1042 		if (EVBUFFER_LENGTH(out) == 0)
1043 			client_close(c);
1044 		break;
1045 	}
1046 }
1047 
1048 static void
1049 client_error(struct bufferevent *bev, short error, void *d)
1050 {
1051 	struct client	*c = d;
1052 
1053 	c->type = REQUEST_DONE;
1054 
1055 	if (error & EVBUFFER_TIMEOUT) {
1056 		log_warn(c, "timeout reached, "
1057 		    "forcefully closing the connection");
1058 		if (c->code == 0)
1059 			start_reply(c, BAD_REQUEST, "timeout");
1060 		else
1061 			client_close(c);
1062 		return;
1063 	}
1064 
1065 	if (error & EVBUFFER_EOF) {
1066 		client_close(c);
1067 		return;
1068 	}
1069 
1070 	log_err(c, "unknown bufferevent error: %s", strerror(errno));
1071 	client_close(c);
1072 }
1073 
1074 void
1075 start_reply(struct client *c, int code, const char *meta)
1076 {
1077 	struct evbuffer	*evb = EVBUFFER_OUTPUT(c->bev);
1078 	const char	*lang;
1079 	int		 r, rr;
1080 
1081 	bufferevent_enable(c->bev, EVBUFFER_WRITE);
1082 
1083 	c->code = code;
1084 	c->meta = meta;
1085 
1086 	r = evbuffer_add_printf(evb, "%d %s", code, meta);
1087 	if (r == -1)
1088 		goto err;
1089 
1090 	/* 2 digit status + space + 1024 max reply */
1091 	if (r > 1027)
1092 		goto overflow;
1093 
1094 	if (c->type != REQUEST_CGI &&
1095 	    c->type != REQUEST_FCGI &&
1096 	    !strcmp(meta, "text/gemini") &&
1097 	    (lang = vhost_lang(c->host, c->iri.path)) != NULL) {
1098                 rr = evbuffer_add_printf(evb, ";lang=%s", lang);
1099 		if (rr == -1)
1100 			goto err;
1101 		if (r + rr > 1027)
1102 			goto overflow;
1103 	}
1104 
1105 	bufferevent_write(c->bev, "\r\n", 2);
1106 
1107 	if (!vhost_disable_log(c->host, c->iri.path))
1108 		log_request(c, EVBUFFER_DATA(evb), EVBUFFER_LENGTH(evb));
1109 
1110 	if (code != 20 && IS_INTERNAL_REQUEST(c->type))
1111 		c->type = REQUEST_DONE;
1112 
1113 	return;
1114 
1115 err:
1116 	log_err(c, "evbuffer_add_printf error: no memory");
1117 	evbuffer_drain(evb, EVBUFFER_LENGTH(evb));
1118 	client_close(c);
1119 	return;
1120 
1121 overflow:
1122 	log_warn(c, "reply header overflow");
1123 	evbuffer_drain(evb, EVBUFFER_LENGTH(evb));
1124 	start_reply(c, TEMP_FAILURE, "internal error");
1125 }
1126 
1127 static void
1128 client_close_ev(int fd, short event, void *d)
1129 {
1130 	struct client	*c = d;
1131 
1132 	switch (tls_close(c->ctx)) {
1133 	case TLS_WANT_POLLIN:
1134 		event_once(c->fd, EV_READ, client_close_ev, c, NULL);
1135 		break;
1136 	case TLS_WANT_POLLOUT:
1137 		event_once(c->fd, EV_WRITE, client_close_ev, c, NULL);
1138 		break;
1139 	}
1140 
1141 	connected_clients--;
1142 
1143 	free(c->req);
1144 
1145 	tls_free(c->ctx);
1146 	c->ctx = NULL;
1147 
1148 	free(c->header);
1149 
1150 	if (c->pfd != -1)
1151 		close(c->pfd);
1152 
1153 	if (c->dir != NULL)
1154 		free(c->dir);
1155 
1156 	close(c->fd);
1157 	c->fd = -1;
1158 }
1159 
1160 void
1161 client_close(struct client *c)
1162 {
1163 	/*
1164 	 * We may end up calling client_close in various situations
1165 	 * and for the most unexpected reasons.  Therefore, we need to
1166 	 * ensure that everything is properly released once we reach
1167 	 * this point.
1168 	 */
1169 
1170 	SPLAY_REMOVE(client_tree_id, &clients, c);
1171 
1172 	if (c->cgibev != NULL) {
1173 		bufferevent_disable(c->cgibev, EVBUFFER_READ|EVBUFFER_WRITE);
1174 		bufferevent_free(c->cgibev);
1175 		c->cgibev = NULL;
1176 		close(c->pfd);
1177 		c->pfd = -1;
1178 	}
1179 
1180 	bufferevent_disable(c->bev, EVBUFFER_READ|EVBUFFER_WRITE);
1181 	bufferevent_free(c->bev);
1182 	c->bev = NULL;
1183 
1184 	client_close_ev(c->fd, 0, c);
1185 }
1186 
1187 static void
1188 cgi_read(struct bufferevent *bev, void *d)
1189 {
1190 	struct client	*client = d;
1191 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
1192 	char		*header;
1193 	size_t		 len;
1194 	int		 code;
1195 
1196 	/* intercept the header */
1197 	if (client->code == 0) {
1198 		header = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
1199 		if (header == NULL) {
1200 			/* max reply + \r\n */
1201 			if (EVBUFFER_LENGTH(src) > 1026) {
1202 				log_warn(client, "CGI script is trying to "
1203 				    "send a header too long.");
1204 				cgi_error(bev, EVBUFFER_READ, client);
1205 			}
1206 
1207 			/* wait a bit */
1208 			return;
1209 		}
1210 
1211 		if (len < 3 || len > 1029 ||
1212 		    !isdigit(header[0]) ||
1213 		    !isdigit(header[1]) ||
1214 		    !isspace(header[2])) {
1215 			free(header);
1216 			log_warn(client, "CGI script is trying to send a "
1217 			    "malformed header");
1218 			cgi_error(bev, EVBUFFER_READ, client);
1219 			return;
1220 		}
1221 
1222 		client->header = header;
1223 		code = (header[0] - '0') * 10 + (header[1] - '0');
1224 
1225 		if (code < 10 || code >= 70) {
1226 			log_warn(client, "CGI script is trying to send an "
1227 			    "invalid reply code (%d)", code);
1228 			cgi_error(bev, EVBUFFER_READ, client);
1229 			return;
1230 		}
1231 
1232 		start_reply(client, code, header + 3);
1233 
1234 		if (client->code < 20 || client->code > 29) {
1235 			cgi_error(client->cgibev, EVBUFFER_EOF, client);
1236 			return;
1237 		}
1238 	}
1239 
1240 	bufferevent_write_buffer(client->bev, src);
1241 }
1242 
1243 static void
1244 cgi_write(struct bufferevent *bev, void *d)
1245 {
1246 	/*
1247 	 * Never called.  We don't send data to a CGI script.
1248 	 */
1249 	abort();
1250 }
1251 
1252 static void
1253 cgi_error(struct bufferevent *bev, short error, void *d)
1254 {
1255 	struct client	*client = d;
1256 
1257 	if (error & EVBUFFER_ERROR)
1258 		log_err(client, "%s: evbuffer error (%x): %s",
1259 		    __func__, error, strerror(errno));
1260 
1261 	bufferevent_disable(bev, EVBUFFER_READ|EVBUFFER_WRITE);
1262 	bufferevent_free(bev);
1263 	client->cgibev = NULL;
1264 
1265 	close(client->pfd);
1266 	client->pfd = -1;
1267 
1268 	client->type = REQUEST_DONE;
1269 	if (client->code != 0)
1270 		client_write(client->bev, client);
1271 	else
1272 		start_reply(client, CGI_ERROR, "CGI error");
1273 }
1274 
1275 static void
1276 do_accept(int sock, short et, void *d)
1277 {
1278 	struct client *c;
1279 	struct sockaddr_storage addr;
1280 	struct sockaddr *saddr;
1281 	socklen_t len;
1282 	int fd;
1283 
1284 	saddr = (struct sockaddr*)&addr;
1285 	len = sizeof(addr);
1286 	if ((fd = accept(sock, saddr, &len)) == -1) {
1287 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1288 			return;
1289 		fatal("accept: %s", strerror(errno));
1290 	}
1291 
1292 	mark_nonblock(fd);
1293 
1294 	c = xcalloc(1, sizeof(*c));
1295 	c->id = ++server_client_id;
1296 	c->fd = fd;
1297 	c->pfd = -1;
1298 	c->addr = addr;
1299 
1300 	if (tls_accept_socket(ctx, &c->ctx, fd) == -1) {
1301 		log_warn(c, "failed to accept socket: %s", tls_error(c->ctx));
1302 		close(c->fd);
1303 		free(c);
1304 		return;
1305 	}
1306 
1307 	SPLAY_INSERT(client_tree_id, &clients, c);
1308 	event_once(c->fd, EV_READ|EV_WRITE, handle_handshake, c, NULL);
1309 	connected_clients++;
1310 }
1311 
1312 static struct client *
1313 client_by_id(int id)
1314 {
1315 	struct client *c;
1316 
1317 	if ((c = try_client_by_id(id)) == NULL)
1318 		fatal("in client_by_id: invalid id %d", id);
1319 	return c;
1320 }
1321 
1322 struct client *
1323 try_client_by_id(int id)
1324 {
1325 	struct client find;
1326 
1327 	find.id = id;
1328 	return SPLAY_FIND(client_tree_id, &clients, &find);
1329 }
1330 
1331 static void
1332 handle_imsg_cgi_res(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1333 {
1334 	struct client *c;
1335 
1336 	c = client_by_id(imsg->hdr.peerid);
1337 
1338 	if ((c->pfd = imsg->fd) == -1) {
1339 		start_reply(c, TEMP_FAILURE, "internal server error");
1340 		return;
1341 	}
1342 
1343 	c->type = REQUEST_CGI;
1344 
1345 	c->cgibev = bufferevent_new(c->pfd, cgi_read, cgi_write,
1346 	    cgi_error, c);
1347 
1348 	bufferevent_enable(c->cgibev, EV_READ);
1349 }
1350 
1351 static void
1352 handle_imsg_fcgi_fd(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1353 {
1354 	struct client	*c;
1355 	int		 id;
1356 
1357 	id = imsg->hdr.peerid;
1358 
1359 	if ((c = try_client_by_id(id)) == NULL) {
1360 		if (imsg->fd != -1)
1361 			close(imsg->fd);
1362 		return;
1363 	}
1364 
1365 	if ((c->pfd = imsg->fd) == -1) {
1366 		start_reply(c, CGI_ERROR, "CGI error");
1367 		return;
1368 	}
1369 
1370 	mark_nonblock(c->pfd);
1371 
1372 	c->cgibev = bufferevent_new(c->pfd, fcgi_read, fcgi_write,
1373 	    fcgi_error, c);
1374 	if (c->cgibev == NULL) {
1375 		start_reply(c, TEMP_FAILURE, "internal server error");
1376 		return;
1377 	}
1378 
1379 	bufferevent_enable(c->cgibev, EV_READ|EV_WRITE);
1380 	fcgi_req(c);
1381 }
1382 
1383 static void
1384 handle_imsg_quit(struct imsgbuf *ibuf, struct imsg *imsg, size_t len)
1385 {
1386 	/*
1387 	 * don't call event_loopbreak since we want to finish to
1388 	 * handle the ongoing connections.
1389 	 */
1390 
1391 	shutting_down = 1;
1392 
1393 	event_del(&e4);
1394 	if (has_ipv6)
1395 		event_del(&e6);
1396 	if (has_siginfo)
1397 		signal_del(&siginfo);
1398 	event_del(&imsgev);
1399 	signal_del(&sigusr2);
1400 }
1401 
1402 static void
1403 handle_dispatch_imsg(int fd, short ev, void *d)
1404 {
1405 	struct imsgbuf *ibuf = d;
1406 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
1407 }
1408 
1409 static void
1410 handle_siginfo(int fd, short ev, void *d)
1411 {
1412 	log_info(NULL, "%d connected clients", connected_clients);
1413 }
1414 
1415 void
1416 loop(struct tls *ctx_, int sock4, int sock6, struct imsgbuf *ibuf)
1417 {
1418 	ctx = ctx_;
1419 
1420 	SPLAY_INIT(&clients);
1421 
1422 	event_init();
1423 
1424 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, NULL);
1425 	event_add(&e4, NULL);
1426 
1427 	if (sock6 != -1) {
1428 		has_ipv6 = 1;
1429 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, NULL);
1430 		event_add(&e6, NULL);
1431 	}
1432 
1433 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
1434 	event_add(&imsgev, NULL);
1435 
1436 #ifdef SIGINFO
1437 	has_siginfo = 1;
1438 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1439 	signal_add(&siginfo, NULL);
1440 #endif
1441 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1442 	signal_add(&sigusr2, NULL);
1443 
1444 	sandbox_server_process();
1445 	event_dispatch();
1446 	_exit(0);
1447 }
1448 
1449 int
1450 client_tree_cmp(struct client *a, struct client *b)
1451 {
1452 	if (a->id == b->id)
1453 		return 0;
1454 	else if (a->id < b->id)
1455 		return -1;
1456 	else
1457 		return +1;
1458 }
1459 
1460 SPLAY_GENERATE(client_tree_id, client, entry, client_tree_cmp)