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Date:: Sun Jan 24 18:53:26 2021 UTC
Message:: added support for location blocks
Actions:: History | Blame | Raw File
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 <sys/mman.h>
18 #include <sys/stat.h>
19 
20 #include <netdb.h>
21 
22 #include <assert.h>
23 #include <errno.h>
24 #include <fcntl.h>
25 #include <fnmatch.h>
26 #include <string.h>
27 
28 #include "gmid.h"
29 
30 int connected_clients;
31 
32 const char *
33 vhost_lang(struct vhost *v, const char *path)
34 {
35 	struct location *loc;
36 	const char *lang = NULL;
37 
38 	for (loc = v->locations; loc->match != NULL; ++loc) {
39 		if (!fnmatch(loc->match, path, 0)) {
40 			if (loc->lang != NULL)
41 				lang = loc->lang;
42 		}
43 	}
44 
45 	return lang;
46 }
47 
48 const char *
49 vhost_default_mime(struct vhost *v, const char *path)
50 {
51 	struct location *loc;
52 	const char *default_mime = "application/octet-stream";
53 
54 	for (loc = v->locations; loc->match != NULL; ++loc) {
55 		if (!fnmatch(loc->match, path, 0)) {
56 			if (loc->default_mime != NULL)
57 				default_mime = loc->default_mime;
58 		}
59 	}
60 
61 	return default_mime;
62 }
63 
64 const char *
65 vhost_index(struct vhost *v, const char *path)
66 {
67 	struct location *loc;
68 	const char *index = "index.gmi";
69 
70 	for (loc = v->locations; loc->match != NULL; ++loc) {
71 		if (!fnmatch(loc->match, path, 0)) {
72 			if (loc->index != NULL)
73 				index = loc->index;
74 		}
75 	}
76 
77 	return index;
78 }
79 
80 int
81 vhost_auto_index(struct vhost *v, const char *path)
82 {
83 	struct location *loc;
84 	int auto_index = 0;
85 
86 	for (loc = v->locations; loc->match != NULL; ++loc) {
87 		if (!fnmatch(loc->match, path, 0)) {
88 			if (loc->auto_index)
89 				auto_index = loc->auto_index;
90 		}
91 	}
92 
93 	return auto_index == 1;
94 }
95 
96 int
97 check_path(struct client *c, const char *path, int *fd)
98 {
99 	struct stat sb;
100 	const char *p;
101 	int flags;
102 
103 	assert(path != NULL);
104 
105 	if (*path == '\0')
106 		p = ".";
107 	else if (*path == '/')
108 		/* in send_dir we add an initial / (to be
109 		 * redirect-friendly), but here we want to skip it */
110 		p = path+1;
111 	else
112 		p = path;
113 
114 	flags = O_RDONLY | O_NOFOLLOW;
115 
116 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
117 		return FILE_MISSING;
118 
119 	if (fstat(*fd, &sb) == -1) {
120 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
121 		return FILE_MISSING;
122 	}
123 
124 	if (S_ISDIR(sb.st_mode))
125 		return FILE_DIRECTORY;
126 
127 	if (sb.st_mode & S_IXUSR)
128 		return FILE_EXECUTABLE;
129 
130 	return FILE_EXISTS;
131 }
132 
133 void
134 open_file(struct pollfd *fds, struct client *c)
135 {
136 	switch (check_path(c, c->iri.path, &c->fd)) {
137 	case FILE_EXECUTABLE:
138 		if (starts_with(c->iri.path, c->host->cgi)) {
139 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
140 			return;
141 		}
142 
143 		/* fallthrough */
144 
145 	case FILE_EXISTS:
146 		load_file(fds, c);
147 		return;
148 
149 	case FILE_DIRECTORY:
150 		open_dir(fds, c);
151 		return;
152 
153 	case FILE_MISSING:
154 		if (c->host->cgi != NULL && starts_with(c->iri.path, c->host->cgi)) {
155 			check_for_cgi(c->iri.path, c->iri.query, fds, c);
156 			return;
157 		}
158 		start_reply(fds, c, NOT_FOUND, "not found");
159 		return;
160 
161 	default:
162 		/* unreachable */
163 		abort();
164 	}
165 }
166 
167 void
168 load_file(struct pollfd *fds, struct client *c)
169 {
170 	if ((c->len = filesize(c->fd)) == -1) {
171 		LOGE(c, "failed to get file size for %s", c->iri.path);
172 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
173 		return;
174 	}
175 
176 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
177 		    c->fd, 0)) == MAP_FAILED) {
178 		LOGW(c, "mmap: %s: %s", c->iri.path, strerror(errno));
179 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
180 		return;
181 	}
182 	c->i = c->buf;
183 	c->next = S_SENDING_FILE;
184 	start_reply(fds, c, SUCCESS, mime(c->host, c->iri.path));
185 }
186 
187 /*
188  * the inverse of this algorithm, i.e. starting from the start of the
189  * path + strlen(cgi), and checking if each component, should be
190  * faster.  But it's tedious to write.  This does the opposite: starts
191  * from the end and strip one component at a time, until either an
192  * executable is found or we emptied the path.
193  */
194 void
195 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
196 {
197 	char *end;
198 	end = strchr(path, '\0');
199 
200 	/* NB: assume CGI is enabled and path matches cgi */
201 
202 	while (end > path) {
203 		/* go up one level.  UNIX paths are simple and POSIX
204 		 * dirname, with its ambiguities on if the given path
205 		 * is changed or not, gives me headaches. */
206 		while (*end != '/')
207 			end--;
208 		*end = '\0';
209 
210 		switch (check_path(c, path, &c->fd)) {
211 		case FILE_EXECUTABLE:
212 			start_cgi(path, end+1, query, fds,c);
213 			return;
214 		case FILE_MISSING:
215 			break;
216 		default:
217 			goto err;
218 		}
219 
220 		*end = '/';
221 		end--;
222 	}
223 
224 err:
225 	start_reply(fds, c, NOT_FOUND, "not found");
226 	return;
227 }
228 
229 void
230 mark_nonblock(int fd)
231 {
232 	int flags;
233 
234 	if ((flags = fcntl(fd, F_GETFL)) == -1)
235 		fatal("fcntl(F_GETFL): %s", strerror(errno));
236 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
237 		fatal("fcntl(F_SETFL): %s", strerror(errno));
238 }
239 
240 void
241 handle_handshake(struct pollfd *fds, struct client *c)
242 {
243 	struct vhost *h;
244 	const char *servname;
245 
246 	switch (tls_handshake(c->ctx)) {
247 	case 0:  /* success */
248 	case -1: /* already handshaked */
249 		break;
250 	case TLS_WANT_POLLIN:
251 		fds->events = POLLIN;
252 		return;
253 	case TLS_WANT_POLLOUT:
254 		fds->events = POLLOUT;
255 		return;
256 	default:
257 		/* unreachable */
258 		abort();
259 	}
260 
261 	servname = tls_conn_servername(c->ctx);
262 
263 	for (h = hosts; h->domain != NULL; ++h) {
264 		if (!strcmp(h->domain, "*"))
265 			break;
266 
267 		if (servname != NULL && !fnmatch(h->domain, servname, 0))
268 			break;
269 	}
270 
271 	if (h->domain != NULL) {
272 		c->state = S_OPEN;
273 		c->host = h;
274 		handle_open_conn(fds, c);
275 		return;
276 	}
277 
278 	if (servname != NULL)
279 		strncpy(c->req, servname, sizeof(c->req));
280 	else
281 		strncpy(c->req, "null", sizeof(c->req));
282 
283 	start_reply(fds, c, BAD_REQUEST, "Wrong host or missing SNI");
284 }
285 
286 void
287 handle_open_conn(struct pollfd *fds, struct client *c)
288 {
289 	const char *parse_err = "invalid request";
290 
291 	bzero(c->req, sizeof(c->req));
292 	bzero(&c->iri, sizeof(c->iri));
293 
294 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
295 	case -1:
296 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
297 		close_conn(fds, c);
298 		return;
299 
300 	case TLS_WANT_POLLIN:
301 		fds->events = POLLIN;
302 		return;
303 
304 	case TLS_WANT_POLLOUT:
305 		fds->events = POLLOUT;
306 		return;
307 	}
308 
309 	if (!trim_req_iri(c->req) || !parse_iri(c->req, &c->iri, &parse_err)) {
310 		start_reply(fds, c, BAD_REQUEST, parse_err);
311 		return;
312 	}
313 
314 	/* XXX: we should check that the SNI matches the requested host */
315 	if (strcmp(c->iri.schema, "gemini") || c->iri.port_no != conf.port) {
316 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
317 		return;
318 	}
319 
320 	open_file(fds, c);
321 }
322 
323 void
324 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
325 {
326 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
327 	const char *lang;
328 	size_t len;
329 
330 	c->code = code;
331 	c->meta = meta;
332 	c->state = S_INITIALIZING;
333 
334 	lang = vhost_lang(c->host, c->iri.path);
335 
336 	snprintf(buf, sizeof(buf), "%d ", code);
337 	strlcat(buf, meta, sizeof(buf));
338 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
339 		strlcat(buf, "; lang=", sizeof(buf));
340 		strlcat(buf, lang, sizeof(buf));
341 	}
342 
343 	len = strlcat(buf, "\r\n", sizeof(buf));
344 	assert(len < sizeof(buf));
345 
346 	switch (tls_write(c->ctx, buf, len)) {
347 	case -1:
348 		close_conn(pfd, c);
349 		return;
350 	case TLS_WANT_POLLIN:
351 		pfd->events = POLLIN;
352 		return;
353 	case TLS_WANT_POLLOUT:
354 		pfd->events = POLLOUT;
355 		return;
356 	}
357 
358 	log_request(c, buf, sizeof(buf));
359 
360 	/* we don't need a body */
361 	if (c->code != SUCCESS) {
362 		close_conn(pfd, c);
363 		return;
364 	}
365 
366 	/* advance the state machine */
367 	c->state = c->next;
368 	handle(pfd, c);
369 }
370 
371 void
372 start_cgi(const char *spath, const char *relpath, const char *query,
373     struct pollfd *fds, struct client *c)
374 {
375 	char addr[NI_MAXHOST];
376 	const char *ruser, *cissuer, *chash;
377 	int e;
378 
379 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
380 	    addr, sizeof(addr),
381 	    NULL, 0,
382 	    NI_NUMERICHOST);
383 	if (e != 0)
384 		goto err;
385 
386 	if (tls_peer_cert_provided(c->ctx)) {
387 		ruser = tls_peer_cert_subject(c->ctx);
388 		cissuer = tls_peer_cert_issuer(c->ctx);
389 		chash = tls_peer_cert_hash(c->ctx);
390 	} else {
391 		ruser = NULL;
392 		cissuer = NULL;
393 		chash = NULL;
394 	}
395 
396 	if (!send_string(exfd, spath)
397 	    || !send_string(exfd, relpath)
398 	    || !send_string(exfd, query)
399 	    || !send_string(exfd, addr)
400 	    || !send_string(exfd, ruser)
401 	    || !send_string(exfd, cissuer)
402 	    || !send_string(exfd, chash)
403 	    || !send_vhost(exfd, c->host))
404 		goto err;
405 
406 	close(c->fd);
407 	if ((c->fd = recv_fd(exfd)) == -1) {
408 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
409 		return;
410 	}
411 	c->state = S_SENDING_CGI;
412 	cgi_poll_on_child(fds, c);
413 	c->code = -1;
414 	/* handle_cgi(fds, c); */
415 	return;
416 
417 err:
418 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
419 	fatal("cannot talk to the executor process");
420 }
421 
422 void
423 send_file(struct pollfd *fds, struct client *c)
424 {
425 	ssize_t ret, len;
426 
427 	/* ensure the correct state */
428 	c->state = S_SENDING_FILE;
429 
430 	len = (c->buf + c->len) - c->i;
431 
432 	while (len > 0) {
433 		switch (ret = tls_write(c->ctx, c->i, len)) {
434 		case -1:
435 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
436 			close_conn(fds, c);
437 			return;
438 
439 		case TLS_WANT_POLLIN:
440 			fds->events = POLLIN;
441 			return;
442 
443 		case TLS_WANT_POLLOUT:
444 			fds->events = POLLOUT;
445 			return;
446 
447 		default:
448 			c->i += ret;
449 			len -= ret;
450 			break;
451 		}
452 	}
453 
454 	close_conn(fds, c);
455 }
456 
457 void
458 open_dir(struct pollfd *fds, struct client *c)
459 {
460 	size_t len;
461 	int dirfd;
462 	char *before_file;
463 
464 	len = strlen(c->iri.path);
465 	if (len > 0 && !ends_with(c->iri.path, "/")) {
466 		redirect_canonical_dir(fds, c);
467 		return;
468 	}
469 
470 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
471 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
472 	if (!ends_with(c->sbuf, "/"))
473 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
474 	before_file = strchr(c->sbuf, '\0');
475 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
476 	    sizeof(c->sbuf));
477 	if (len >= sizeof(c->sbuf)) {
478 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
479 		return;
480 	}
481 
482 	c->iri.path = c->sbuf;
483 
484 	/* close later unless we have to generate the dir listing */
485 	dirfd = c->fd;
486 	c->fd = -1;
487 
488 	switch (check_path(c, c->iri.path, &c->fd)) {
489 	case FILE_EXECUTABLE:
490 		if (starts_with(c->iri.path, c->host->cgi)) {
491 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
492 			break;
493 		}
494 
495 		/* fallthrough */
496 
497 	case FILE_EXISTS:
498                 load_file(fds, c);
499 		break;
500 
501 	case FILE_DIRECTORY:
502 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
503 		break;
504 
505 	case FILE_MISSING:
506 		*before_file = '\0';
507 
508 		if (!vhost_auto_index(c->host, c->iri.path)) {
509 			start_reply(fds, c, NOT_FOUND, "not found");
510 			break;
511 		}
512 
513 		c->fd = dirfd;
514 		c->next = S_SENDING_DIR;
515 
516 		if ((c->dir = fdopendir(c->fd)) == NULL) {
517 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
518 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
519 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
520 			return;
521 		}
522 		c->off = 0;
523 
524                 start_reply(fds, c, SUCCESS, "text/gemini");
525 		return;
526 
527 	default:
528 		/* unreachable */
529 		abort();
530 	}
531 
532 	close(dirfd);
533 }
534 
535 void
536 redirect_canonical_dir(struct pollfd *fds, struct client *c)
537 {
538 	size_t len;
539 
540 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
541 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
542 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
543 
544 	if (len >= sizeof(c->sbuf)) {
545 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
546 		return;
547 	}
548 
549 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
550 }
551 
552 int
553 read_next_dir_entry(struct client *c)
554 {
555 	struct dirent *d;
556 
557 	do {
558 		errno = 0;
559 		if ((d = readdir(c->dir)) == NULL) {
560 			if (errno != 0)
561 				LOGE(c, "readdir: %s", strerror(errno));
562 			return 0;
563 		}
564 	} while (!strcmp(d->d_name, "."));
565 
566 	/* XXX: url escape */
567 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
568 	    d->d_name, d->d_name);
569 	c->len = strlen(c->sbuf);
570 	c->off = 0;
571 
572 	return 1;
573 }
574 
575 void
576 send_directory_listing(struct pollfd *fds, struct client *c)
577 {
578 	ssize_t r;
579 
580 	while (1) {
581 		if (c->len == 0) {
582 			if (!read_next_dir_entry(c))
583 				goto end;
584 		}
585 
586 		while (c->len > 0) {
587 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
588 			case -1:
589 				goto end;
590 
591 			case TLS_WANT_POLLOUT:
592 				fds->events = POLLOUT;
593 				return;
594 
595 			case TLS_WANT_POLLIN:
596 				fds->events = POLLIN;
597 				return;
598 
599 			default:
600 				c->off += r;
601 				c->len -= r;
602 				break;
603 			}
604 		}
605 	}
606 
607 end:
608 	close_conn(fds, c);
609 }
610 
611 void
612 cgi_poll_on_child(struct pollfd *fds, struct client *c)
613 {
614 	int fd;
615 
616 	if (c->waiting_on_child)
617 		return;
618 	c->waiting_on_child = 1;
619 
620 	fds->events = POLLIN;
621 
622 	fd = fds->fd;
623 	fds->fd = c->fd;
624 	c->fd = fd;
625 }
626 
627 void
628 cgi_poll_on_client(struct pollfd *fds, struct client *c)
629 {
630 	int fd;
631 
632 	if (!c->waiting_on_child)
633 		return;
634 	c->waiting_on_child = 0;
635 
636 	fd = fds->fd;
637 	fds->fd = c->fd;
638 	c->fd = fd;
639 }
640 
641 /* handle the read from the child process.  Return like read(2) */
642 static ssize_t
643 read_from_cgi(struct client *c)
644 {
645 	void	*buf;
646 	size_t	 len;
647 	ssize_t	 r;
648 
649 	/* if we haven't read a whole response line, we want to
650 	 * continue reading. */
651 
652 	if (c->code == -1) {
653 		buf = c->sbuf + c->len;
654 		len = sizeof(c->sbuf) - c->len;
655 	} else {
656 		buf = c->sbuf;
657 		len = sizeof(c->sbuf);
658 	}
659 
660 	r = read(c->fd, buf, len);
661 	if (r == 0 || r == -1)
662 		return r;
663 
664 	c->len += r;
665 	c->off = 0;
666 
667 	if (c->code != -1)
668 		return r;
669 
670 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
671 		c->code = 0;
672 		log_request(c, c->sbuf, c->len);
673 	}
674 
675 	return r;
676 }
677 
678 void
679 handle_cgi(struct pollfd *fds, struct client *c)
680 {
681 	ssize_t r;
682 
683 	/* ensure c->fd is the child and fds->fd the client */
684 	cgi_poll_on_client(fds, c);
685 
686 	while (1) {
687 		if (c->code == -1 || c->len == 0) {
688 			switch (r = read_from_cgi(c)) {
689 			case 0:
690 				goto end;
691 
692 			case -1:
693 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
694 					cgi_poll_on_child(fds, c);
695 					return;
696 				}
697 				goto end;
698 			}
699 		}
700 
701 		if (c->code == -1) {
702 			cgi_poll_on_child(fds, c);
703 			return;
704 		}
705 
706 		while (c->len > 0) {
707 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
708 			case -1:
709 				goto end;
710 
711 			case TLS_WANT_POLLOUT:
712 				fds->events = POLLOUT;
713 				return;
714 
715 			case TLS_WANT_POLLIN:
716 				fds->events = POLLIN;
717 				return;
718 
719 			default:
720                                 c->off += r;
721 				c->len -= r;
722 				break;
723 			}
724 		}
725 	}
726 
727 end:
728 	close_conn(fds, c);
729 }
730 
731 void
732 close_conn(struct pollfd *pfd, struct client *c)
733 {
734 	c->state = S_CLOSING;
735 
736 	switch (tls_close(c->ctx)) {
737 	case TLS_WANT_POLLIN:
738 		pfd->events = POLLIN;
739 		return;
740 	case TLS_WANT_POLLOUT:
741 		pfd->events = POLLOUT;
742 		return;
743 	}
744 
745 	connected_clients--;
746 
747 	tls_free(c->ctx);
748 	c->ctx = NULL;
749 
750 	if (c->buf != MAP_FAILED)
751 		munmap(c->buf, c->len);
752 
753 	if (c->fd != -1)
754 		close(c->fd);
755 
756 	if (c->dir != NULL)
757 		closedir(c->dir);
758 
759 	close(pfd->fd);
760 	pfd->fd = -1;
761 }
762 
763 void
764 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
765 {
766 	int i, fd;
767 	struct sockaddr_storage addr;
768 	socklen_t len;
769 
770 	len = sizeof(addr);
771 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
772 		if (errno == EWOULDBLOCK)
773 			return;
774 		fatal("accept: %s", strerror(errno));
775 	}
776 
777 	mark_nonblock(fd);
778 
779 	for (i = 0; i < MAX_USERS; ++i) {
780 		if (fds[i].fd == -1) {
781 			bzero(&clients[i], sizeof(struct client));
782 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
783 				break; /* goodbye fd! */
784 
785 			fds[i].fd = fd;
786 			fds[i].events = POLLIN;
787 
788 			clients[i].state = S_HANDSHAKE;
789 			clients[i].next = S_SENDING_FILE;
790 			clients[i].fd = -1;
791 			clients[i].waiting_on_child = 0;
792 			clients[i].buf = MAP_FAILED;
793 			clients[i].dir = NULL;
794 			clients[i].addr = addr;
795 
796 			connected_clients++;
797 			return;
798 		}
799 	}
800 
801 	close(fd);
802 }
803 
804 void
805 handle(struct pollfd *fds, struct client *client)
806 {
807 	switch (client->state) {
808 	case S_HANDSHAKE:
809 		handle_handshake(fds, client);
810 		break;
811 
812 	case S_OPEN:
813                 handle_open_conn(fds, client);
814 		break;
815 
816 	case S_INITIALIZING:
817 		start_reply(fds, client, client->code, client->meta);
818                 break;
819 
820 	case S_SENDING_FILE:
821 		send_file(fds, client);
822 		break;
823 
824 	case S_SENDING_DIR:
825 		send_directory_listing(fds, client);
826 		break;
827 
828 	case S_SENDING_CGI:
829 		handle_cgi(fds, client);
830 		break;
831 
832 	case S_CLOSING:
833 		close_conn(fds, client);
834 		break;
835 
836 	default:
837 		/* unreachable */
838 		abort();
839 	}
840 }
841 
842 void
843 loop(struct tls *ctx, int sock4, int sock6)
844 {
845 	int i;
846 	struct client clients[MAX_USERS];
847 	struct pollfd fds[MAX_USERS];
848 
849 	connected_clients = 0;
850 
851 	for (i = 0; i < MAX_USERS; ++i) {
852 		fds[i].fd = -1;
853 		fds[i].events = POLLIN;
854 		bzero(&clients[i], sizeof(struct client));
855 	}
856 
857 	fds[0].fd = sock4;
858 	fds[1].fd = sock6;
859 
860 	for (;;) {
861 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
862 			if (errno == EINTR) {
863                                 fprintf(stderr, "connected clients: %d\n",
864 				    connected_clients);
865 				continue;
866 			}
867 			fatal("poll: %s", strerror(errno));
868 		}
869 
870 		for (i = 0; i < MAX_USERS; i++) {
871 			if (fds[i].revents == 0)
872 				continue;
873 
874 			if (fds[i].revents & (POLLERR|POLLNVAL))
875 				fatal("bad fd %d: %s", fds[i].fd,
876 				    strerror(errno));
877 
878 			if (fds[i].revents & POLLHUP) {
879 				/* fds[i] may be the fd of the stdin
880 				 * of a cgi script that has exited. */
881 				if (!clients[i].waiting_on_child) {
882 					close_conn(&fds[i], &clients[i]);
883 					continue;
884 				}
885 			}
886 
887 			if (fds[i].fd == sock4)
888 				do_accept(sock4, ctx, fds, clients);
889 			else if (fds[i].fd == sock6)
890 				do_accept(sock6, ctx, fds, clients);
891 			else
892 				handle(&fds[i], &clients[i]);
893 		}
894 	}
895 }