op public repos

Blob

Date:: Mon Jan 25 14:08:31 2021 UTC
Message:: rework the configless mode: change flags and generate certs
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 	if (v == NULL)
39 		return lang;
40 
41 	for (loc = v->locations; loc->match != NULL; ++loc) {
42 		if (!fnmatch(loc->match, path, 0)) {
43 			if (loc->lang != NULL)
44 				lang = loc->lang;
45 		}
46 	}
47 
48 	return lang;
49 }
50 
51 const char *
52 vhost_default_mime(struct vhost *v, const char *path)
53 {
54 	struct location *loc;
55 	const char *default_mime = "application/octet-stream";
56 
57 	for (loc = v->locations; loc->match != NULL; ++loc) {
58 		if (!fnmatch(loc->match, path, 0)) {
59 			if (loc->default_mime != NULL)
60 				default_mime = loc->default_mime;
61 		}
62 	}
63 
64 	return default_mime;
65 }
66 
67 const char *
68 vhost_index(struct vhost *v, const char *path)
69 {
70 	struct location *loc;
71 	const char *index = "index.gmi";
72 
73 	for (loc = v->locations; loc->match != NULL; ++loc) {
74 		if (!fnmatch(loc->match, path, 0)) {
75 			if (loc->index != NULL)
76 				index = loc->index;
77 		}
78 	}
79 
80 	return index;
81 }
82 
83 int
84 vhost_auto_index(struct vhost *v, const char *path)
85 {
86 	struct location *loc;
87 	int auto_index = 0;
88 
89 	for (loc = v->locations; loc->match != NULL; ++loc) {
90 		if (!fnmatch(loc->match, path, 0)) {
91 			if (loc->auto_index)
92 				auto_index = loc->auto_index;
93 		}
94 	}
95 
96 	return auto_index == 1;
97 }
98 
99 int
100 check_path(struct client *c, const char *path, int *fd)
101 {
102 	struct stat sb;
103 	const char *p;
104 	int flags;
105 
106 	assert(path != NULL);
107 
108 	if (*path == '\0')
109 		p = ".";
110 	else if (*path == '/')
111 		/* in send_dir we add an initial / (to be
112 		 * redirect-friendly), but here we want to skip it */
113 		p = path+1;
114 	else
115 		p = path;
116 
117 	flags = O_RDONLY | O_NOFOLLOW;
118 
119 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
120 		return FILE_MISSING;
121 
122 	if (fstat(*fd, &sb) == -1) {
123 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
124 		return FILE_MISSING;
125 	}
126 
127 	if (S_ISDIR(sb.st_mode))
128 		return FILE_DIRECTORY;
129 
130 	if (sb.st_mode & S_IXUSR)
131 		return FILE_EXECUTABLE;
132 
133 	return FILE_EXISTS;
134 }
135 
136 void
137 open_file(struct pollfd *fds, struct client *c)
138 {
139 	switch (check_path(c, c->iri.path, &c->fd)) {
140 	case FILE_EXECUTABLE:
141 		if (starts_with(c->iri.path, c->host->cgi)) {
142 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
143 			return;
144 		}
145 
146 		/* fallthrough */
147 
148 	case FILE_EXISTS:
149 		load_file(fds, c);
150 		return;
151 
152 	case FILE_DIRECTORY:
153 		open_dir(fds, c);
154 		return;
155 
156 	case FILE_MISSING:
157 		if (c->host->cgi != NULL && starts_with(c->iri.path, c->host->cgi)) {
158 			check_for_cgi(c->iri.path, c->iri.query, fds, c);
159 			return;
160 		}
161 		start_reply(fds, c, NOT_FOUND, "not found");
162 		return;
163 
164 	default:
165 		/* unreachable */
166 		abort();
167 	}
168 }
169 
170 void
171 load_file(struct pollfd *fds, struct client *c)
172 {
173 	if ((c->len = filesize(c->fd)) == -1) {
174 		LOGE(c, "failed to get file size for %s", c->iri.path);
175 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
176 		return;
177 	}
178 
179 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
180 		    c->fd, 0)) == MAP_FAILED) {
181 		LOGW(c, "mmap: %s: %s", c->iri.path, strerror(errno));
182 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
183 		return;
184 	}
185 	c->i = c->buf;
186 	c->next = S_SENDING_FILE;
187 	start_reply(fds, c, SUCCESS, mime(c->host, c->iri.path));
188 }
189 
190 /*
191  * the inverse of this algorithm, i.e. starting from the start of the
192  * path + strlen(cgi), and checking if each component, should be
193  * faster.  But it's tedious to write.  This does the opposite: starts
194  * from the end and strip one component at a time, until either an
195  * executable is found or we emptied the path.
196  */
197 void
198 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
199 {
200 	char *end;
201 	end = strchr(path, '\0');
202 
203 	/* NB: assume CGI is enabled and path matches cgi */
204 
205 	while (end > path) {
206 		/* go up one level.  UNIX paths are simple and POSIX
207 		 * dirname, with its ambiguities on if the given path
208 		 * is changed or not, gives me headaches. */
209 		while (*end != '/')
210 			end--;
211 		*end = '\0';
212 
213 		switch (check_path(c, path, &c->fd)) {
214 		case FILE_EXECUTABLE:
215 			start_cgi(path, end+1, query, fds,c);
216 			return;
217 		case FILE_MISSING:
218 			break;
219 		default:
220 			goto err;
221 		}
222 
223 		*end = '/';
224 		end--;
225 	}
226 
227 err:
228 	start_reply(fds, c, NOT_FOUND, "not found");
229 	return;
230 }
231 
232 void
233 mark_nonblock(int fd)
234 {
235 	int flags;
236 
237 	if ((flags = fcntl(fd, F_GETFL)) == -1)
238 		fatal("fcntl(F_GETFL): %s", strerror(errno));
239 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
240 		fatal("fcntl(F_SETFL): %s", strerror(errno));
241 }
242 
243 void
244 handle_handshake(struct pollfd *fds, struct client *c)
245 {
246 	struct vhost *h;
247 	const char *servname;
248 
249 	switch (tls_handshake(c->ctx)) {
250 	case 0:  /* success */
251 	case -1: /* already handshaked */
252 		break;
253 	case TLS_WANT_POLLIN:
254 		fds->events = POLLIN;
255 		return;
256 	case TLS_WANT_POLLOUT:
257 		fds->events = POLLOUT;
258 		return;
259 	default:
260 		/* unreachable */
261 		abort();
262 	}
263 
264 	servname = tls_conn_servername(c->ctx);
265 
266 	for (h = hosts; h->domain != NULL; ++h) {
267 		if (!strcmp(h->domain, "*"))
268 			break;
269 
270 		if (servname != NULL && !fnmatch(h->domain, servname, 0))
271 			break;
272 	}
273 
274 	if (h->domain != NULL) {
275 		c->state = S_OPEN;
276 		c->host = h;
277 		handle_open_conn(fds, c);
278 		return;
279 	}
280 
281 	if (servname != NULL)
282 		strncpy(c->req, servname, sizeof(c->req));
283 	else
284 		strncpy(c->req, "null", sizeof(c->req));
285 
286 	start_reply(fds, c, BAD_REQUEST, "Wrong host or missing SNI");
287 }
288 
289 void
290 handle_open_conn(struct pollfd *fds, struct client *c)
291 {
292 	const char *parse_err = "invalid request";
293 
294 	bzero(c->req, sizeof(c->req));
295 	bzero(&c->iri, sizeof(c->iri));
296 
297 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
298 	case -1:
299 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
300 		close_conn(fds, c);
301 		return;
302 
303 	case TLS_WANT_POLLIN:
304 		fds->events = POLLIN;
305 		return;
306 
307 	case TLS_WANT_POLLOUT:
308 		fds->events = POLLOUT;
309 		return;
310 	}
311 
312 	if (!trim_req_iri(c->req) || !parse_iri(c->req, &c->iri, &parse_err)) {
313 		start_reply(fds, c, BAD_REQUEST, parse_err);
314 		return;
315 	}
316 
317 	/* XXX: we should check that the SNI matches the requested host */
318 	if (strcmp(c->iri.schema, "gemini") || c->iri.port_no != conf.port) {
319 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
320 		return;
321 	}
322 
323 	open_file(fds, c);
324 }
325 
326 void
327 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
328 {
329 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
330 	const char *lang;
331 	size_t len;
332 
333 	c->code = code;
334 	c->meta = meta;
335 	c->state = S_INITIALIZING;
336 
337 	lang = vhost_lang(c->host, c->iri.path);
338 
339 	snprintf(buf, sizeof(buf), "%d ", code);
340 	strlcat(buf, meta, sizeof(buf));
341 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
342 		strlcat(buf, "; lang=", sizeof(buf));
343 		strlcat(buf, lang, sizeof(buf));
344 	}
345 
346 	len = strlcat(buf, "\r\n", sizeof(buf));
347 	assert(len < sizeof(buf));
348 
349 	switch (tls_write(c->ctx, buf, len)) {
350 	case -1:
351 		close_conn(pfd, c);
352 		return;
353 	case TLS_WANT_POLLIN:
354 		pfd->events = POLLIN;
355 		return;
356 	case TLS_WANT_POLLOUT:
357 		pfd->events = POLLOUT;
358 		return;
359 	}
360 
361 	log_request(c, buf, sizeof(buf));
362 
363 	/* we don't need a body */
364 	if (c->code != SUCCESS) {
365 		close_conn(pfd, c);
366 		return;
367 	}
368 
369 	/* advance the state machine */
370 	c->state = c->next;
371 	handle(pfd, c);
372 }
373 
374 void
375 start_cgi(const char *spath, const char *relpath, const char *query,
376     struct pollfd *fds, struct client *c)
377 {
378 	char addr[NI_MAXHOST];
379 	const char *ruser, *cissuer, *chash;
380 	int e;
381 
382 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
383 	    addr, sizeof(addr),
384 	    NULL, 0,
385 	    NI_NUMERICHOST);
386 	if (e != 0)
387 		goto err;
388 
389 	if (tls_peer_cert_provided(c->ctx)) {
390 		ruser = tls_peer_cert_subject(c->ctx);
391 		cissuer = tls_peer_cert_issuer(c->ctx);
392 		chash = tls_peer_cert_hash(c->ctx);
393 	} else {
394 		ruser = NULL;
395 		cissuer = NULL;
396 		chash = NULL;
397 	}
398 
399 	if (!send_string(exfd, spath)
400 	    || !send_string(exfd, relpath)
401 	    || !send_string(exfd, query)
402 	    || !send_string(exfd, addr)
403 	    || !send_string(exfd, ruser)
404 	    || !send_string(exfd, cissuer)
405 	    || !send_string(exfd, chash)
406 	    || !send_vhost(exfd, c->host))
407 		goto err;
408 
409 	close(c->fd);
410 	if ((c->fd = recv_fd(exfd)) == -1) {
411 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
412 		return;
413 	}
414 	c->state = S_SENDING_CGI;
415 	cgi_poll_on_child(fds, c);
416 	c->code = -1;
417 	/* handle_cgi(fds, c); */
418 	return;
419 
420 err:
421 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
422 	fatal("cannot talk to the executor process");
423 }
424 
425 void
426 send_file(struct pollfd *fds, struct client *c)
427 {
428 	ssize_t ret, len;
429 
430 	/* ensure the correct state */
431 	c->state = S_SENDING_FILE;
432 
433 	len = (c->buf + c->len) - c->i;
434 
435 	while (len > 0) {
436 		switch (ret = tls_write(c->ctx, c->i, len)) {
437 		case -1:
438 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
439 			close_conn(fds, c);
440 			return;
441 
442 		case TLS_WANT_POLLIN:
443 			fds->events = POLLIN;
444 			return;
445 
446 		case TLS_WANT_POLLOUT:
447 			fds->events = POLLOUT;
448 			return;
449 
450 		default:
451 			c->i += ret;
452 			len -= ret;
453 			break;
454 		}
455 	}
456 
457 	close_conn(fds, c);
458 }
459 
460 void
461 open_dir(struct pollfd *fds, struct client *c)
462 {
463 	size_t len;
464 	int dirfd;
465 	char *before_file;
466 
467 	len = strlen(c->iri.path);
468 	if (len > 0 && !ends_with(c->iri.path, "/")) {
469 		redirect_canonical_dir(fds, c);
470 		return;
471 	}
472 
473 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
474 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
475 	if (!ends_with(c->sbuf, "/"))
476 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
477 	before_file = strchr(c->sbuf, '\0');
478 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
479 	    sizeof(c->sbuf));
480 	if (len >= sizeof(c->sbuf)) {
481 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
482 		return;
483 	}
484 
485 	c->iri.path = c->sbuf;
486 
487 	/* close later unless we have to generate the dir listing */
488 	dirfd = c->fd;
489 	c->fd = -1;
490 
491 	switch (check_path(c, c->iri.path, &c->fd)) {
492 	case FILE_EXECUTABLE:
493 		if (starts_with(c->iri.path, c->host->cgi)) {
494 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
495 			break;
496 		}
497 
498 		/* fallthrough */
499 
500 	case FILE_EXISTS:
501                 load_file(fds, c);
502 		break;
503 
504 	case FILE_DIRECTORY:
505 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
506 		break;
507 
508 	case FILE_MISSING:
509 		*before_file = '\0';
510 
511 		if (!vhost_auto_index(c->host, c->iri.path)) {
512 			start_reply(fds, c, NOT_FOUND, "not found");
513 			break;
514 		}
515 
516 		c->fd = dirfd;
517 		c->next = S_SENDING_DIR;
518 
519 		if ((c->dir = fdopendir(c->fd)) == NULL) {
520 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
521 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
522 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
523 			return;
524 		}
525 		c->off = 0;
526 
527                 start_reply(fds, c, SUCCESS, "text/gemini");
528 		return;
529 
530 	default:
531 		/* unreachable */
532 		abort();
533 	}
534 
535 	close(dirfd);
536 }
537 
538 void
539 redirect_canonical_dir(struct pollfd *fds, struct client *c)
540 {
541 	size_t len;
542 
543 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
544 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
545 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
546 
547 	if (len >= sizeof(c->sbuf)) {
548 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
549 		return;
550 	}
551 
552 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
553 }
554 
555 int
556 read_next_dir_entry(struct client *c)
557 {
558 	struct dirent *d;
559 
560 	do {
561 		errno = 0;
562 		if ((d = readdir(c->dir)) == NULL) {
563 			if (errno != 0)
564 				LOGE(c, "readdir: %s", strerror(errno));
565 			return 0;
566 		}
567 	} while (!strcmp(d->d_name, "."));
568 
569 	/* XXX: url escape */
570 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
571 	    d->d_name, d->d_name);
572 	c->len = strlen(c->sbuf);
573 	c->off = 0;
574 
575 	return 1;
576 }
577 
578 void
579 send_directory_listing(struct pollfd *fds, struct client *c)
580 {
581 	ssize_t r;
582 
583 	while (1) {
584 		if (c->len == 0) {
585 			if (!read_next_dir_entry(c))
586 				goto end;
587 		}
588 
589 		while (c->len > 0) {
590 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
591 			case -1:
592 				goto end;
593 
594 			case TLS_WANT_POLLOUT:
595 				fds->events = POLLOUT;
596 				return;
597 
598 			case TLS_WANT_POLLIN:
599 				fds->events = POLLIN;
600 				return;
601 
602 			default:
603 				c->off += r;
604 				c->len -= r;
605 				break;
606 			}
607 		}
608 	}
609 
610 end:
611 	close_conn(fds, c);
612 }
613 
614 void
615 cgi_poll_on_child(struct pollfd *fds, struct client *c)
616 {
617 	int fd;
618 
619 	if (c->waiting_on_child)
620 		return;
621 	c->waiting_on_child = 1;
622 
623 	fds->events = POLLIN;
624 
625 	fd = fds->fd;
626 	fds->fd = c->fd;
627 	c->fd = fd;
628 }
629 
630 void
631 cgi_poll_on_client(struct pollfd *fds, struct client *c)
632 {
633 	int fd;
634 
635 	if (!c->waiting_on_child)
636 		return;
637 	c->waiting_on_child = 0;
638 
639 	fd = fds->fd;
640 	fds->fd = c->fd;
641 	c->fd = fd;
642 }
643 
644 /* handle the read from the child process.  Return like read(2) */
645 static ssize_t
646 read_from_cgi(struct client *c)
647 {
648 	void	*buf;
649 	size_t	 len;
650 	ssize_t	 r;
651 
652 	/* if we haven't read a whole response line, we want to
653 	 * continue reading. */
654 
655 	if (c->code == -1) {
656 		buf = c->sbuf + c->len;
657 		len = sizeof(c->sbuf) - c->len;
658 	} else {
659 		buf = c->sbuf;
660 		len = sizeof(c->sbuf);
661 	}
662 
663 	r = read(c->fd, buf, len);
664 	if (r == 0 || r == -1)
665 		return r;
666 
667 	c->len += r;
668 	c->off = 0;
669 
670 	if (c->code != -1)
671 		return r;
672 
673 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
674 		c->code = 0;
675 		log_request(c, c->sbuf, c->len);
676 	}
677 
678 	return r;
679 }
680 
681 void
682 handle_cgi(struct pollfd *fds, struct client *c)
683 {
684 	ssize_t r;
685 
686 	/* ensure c->fd is the child and fds->fd the client */
687 	cgi_poll_on_client(fds, c);
688 
689 	while (1) {
690 		if (c->code == -1 || c->len == 0) {
691 			switch (r = read_from_cgi(c)) {
692 			case 0:
693 				goto end;
694 
695 			case -1:
696 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
697 					cgi_poll_on_child(fds, c);
698 					return;
699 				}
700 				goto end;
701 			}
702 		}
703 
704 		if (c->code == -1) {
705 			cgi_poll_on_child(fds, c);
706 			return;
707 		}
708 
709 		while (c->len > 0) {
710 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
711 			case -1:
712 				goto end;
713 
714 			case TLS_WANT_POLLOUT:
715 				fds->events = POLLOUT;
716 				return;
717 
718 			case TLS_WANT_POLLIN:
719 				fds->events = POLLIN;
720 				return;
721 
722 			default:
723                                 c->off += r;
724 				c->len -= r;
725 				break;
726 			}
727 		}
728 	}
729 
730 end:
731 	close_conn(fds, c);
732 }
733 
734 void
735 close_conn(struct pollfd *pfd, struct client *c)
736 {
737 	c->state = S_CLOSING;
738 
739 	switch (tls_close(c->ctx)) {
740 	case TLS_WANT_POLLIN:
741 		pfd->events = POLLIN;
742 		return;
743 	case TLS_WANT_POLLOUT:
744 		pfd->events = POLLOUT;
745 		return;
746 	}
747 
748 	connected_clients--;
749 
750 	tls_free(c->ctx);
751 	c->ctx = NULL;
752 
753 	if (c->buf != MAP_FAILED)
754 		munmap(c->buf, c->len);
755 
756 	if (c->fd != -1)
757 		close(c->fd);
758 
759 	if (c->dir != NULL)
760 		closedir(c->dir);
761 
762 	close(pfd->fd);
763 	pfd->fd = -1;
764 }
765 
766 void
767 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
768 {
769 	int i, fd;
770 	struct sockaddr_storage addr;
771 	socklen_t len;
772 
773 	len = sizeof(addr);
774 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
775 		if (errno == EWOULDBLOCK)
776 			return;
777 		fatal("accept: %s", strerror(errno));
778 	}
779 
780 	mark_nonblock(fd);
781 
782 	for (i = 0; i < MAX_USERS; ++i) {
783 		if (fds[i].fd == -1) {
784 			bzero(&clients[i], sizeof(struct client));
785 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
786 				break; /* goodbye fd! */
787 
788 			fds[i].fd = fd;
789 			fds[i].events = POLLIN;
790 
791 			clients[i].state = S_HANDSHAKE;
792 			clients[i].next = S_SENDING_FILE;
793 			clients[i].fd = -1;
794 			clients[i].waiting_on_child = 0;
795 			clients[i].buf = MAP_FAILED;
796 			clients[i].dir = NULL;
797 			clients[i].addr = addr;
798 
799 			connected_clients++;
800 			return;
801 		}
802 	}
803 
804 	close(fd);
805 }
806 
807 void
808 handle(struct pollfd *fds, struct client *client)
809 {
810 	switch (client->state) {
811 	case S_HANDSHAKE:
812 		handle_handshake(fds, client);
813 		break;
814 
815 	case S_OPEN:
816                 handle_open_conn(fds, client);
817 		break;
818 
819 	case S_INITIALIZING:
820 		start_reply(fds, client, client->code, client->meta);
821                 break;
822 
823 	case S_SENDING_FILE:
824 		send_file(fds, client);
825 		break;
826 
827 	case S_SENDING_DIR:
828 		send_directory_listing(fds, client);
829 		break;
830 
831 	case S_SENDING_CGI:
832 		handle_cgi(fds, client);
833 		break;
834 
835 	case S_CLOSING:
836 		close_conn(fds, client);
837 		break;
838 
839 	default:
840 		/* unreachable */
841 		abort();
842 	}
843 }
844 
845 void
846 loop(struct tls *ctx, int sock4, int sock6)
847 {
848 	int i;
849 	struct client clients[MAX_USERS];
850 	struct pollfd fds[MAX_USERS];
851 
852 	connected_clients = 0;
853 
854 	for (i = 0; i < MAX_USERS; ++i) {
855 		fds[i].fd = -1;
856 		fds[i].events = POLLIN;
857 		bzero(&clients[i], sizeof(struct client));
858 	}
859 
860 	fds[0].fd = sock4;
861 	fds[1].fd = sock6;
862 
863 	for (;;) {
864 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
865 			if (errno == EINTR) {
866                                 fprintf(stderr, "connected clients: %d\n",
867 				    connected_clients);
868 				continue;
869 			}
870 			fatal("poll: %s", strerror(errno));
871 		}
872 
873 		for (i = 0; i < MAX_USERS; i++) {
874 			if (fds[i].revents == 0)
875 				continue;
876 
877 			if (fds[i].revents & (POLLERR|POLLNVAL))
878 				fatal("bad fd %d: %s", fds[i].fd,
879 				    strerror(errno));
880 
881 			if (fds[i].revents & POLLHUP) {
882 				/* fds[i] may be the fd of the stdin
883 				 * of a cgi script that has exited. */
884 				if (!clients[i].waiting_on_child) {
885 					close_conn(&fds[i], &clients[i]);
886 					continue;
887 				}
888 			}
889 
890 			if (fds[i].fd == sock4)
891 				do_accept(sock4, ctx, fds, clients);
892 			else if (fds[i].fd == sock6)
893 				do_accept(sock6, ctx, fds, clients);
894 			else
895 				handle(&fds[i], &clients[i]);
896 		}
897 	}
898 }