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Date:: Wed Jan 27 15:05:16 2021 UTC
Message:: trim_req_iri: set error string
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1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <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 	puny_decode(servname, c->domain, sizeof(c->domain));
266 
267 	for (h = hosts; h->domain != NULL; ++h) {
268 		if (!fnmatch(h->domain, c->domain, 0))
269 			break;
270 	}
271 
272 	if (h->domain != NULL) {
273 		c->state = S_OPEN;
274 		c->host = h;
275 		handle_open_conn(fds, c);
276 		return;
277 	}
278 
279 	if (servname != NULL)
280 		strncpy(c->req, servname, sizeof(c->req));
281 	else
282 		strncpy(c->req, "null", sizeof(c->req));
283 
284 	start_reply(fds, c, BAD_REQUEST, "Wrong host or missing SNI");
285 }
286 
287 void
288 handle_open_conn(struct pollfd *fds, struct client *c)
289 {
290 	const char *parse_err = "invalid request";
291 	char decoded[DOMAIN_NAME_LEN];
292 
293 	bzero(c->req, sizeof(c->req));
294 	bzero(&c->iri, sizeof(c->iri));
295 
296 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
297 	case -1:
298 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
299 		close_conn(fds, c);
300 		return;
301 
302 	case TLS_WANT_POLLIN:
303 		fds->events = POLLIN;
304 		return;
305 
306 	case TLS_WANT_POLLOUT:
307 		fds->events = POLLOUT;
308 		return;
309 	}
310 
311 	if (!trim_req_iri(c->req, &parse_err)
312 	    || !parse_iri(c->req, &c->iri, &parse_err)) {
313 		LOGI(c, "iri parse error: %s", parse_err);
314 		start_reply(fds, c, BAD_REQUEST, "invalid request");
315 		return;
316 	}
317 
318 	puny_decode(c->iri.host, decoded, sizeof(decoded));
319 
320 	if (c->iri.port_no != conf.port
321 	    || strcmp(c->iri.schema, "gemini")
322 	    || strcmp(decoded, c->domain)) {
323 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
324 		return;
325 	}
326 
327 	open_file(fds, c);
328 }
329 
330 void
331 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
332 {
333 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
334 	const char *lang;
335 	size_t len;
336 
337 	c->code = code;
338 	c->meta = meta;
339 	c->state = S_INITIALIZING;
340 
341 	lang = vhost_lang(c->host, c->iri.path);
342 
343 	snprintf(buf, sizeof(buf), "%d ", code);
344 	strlcat(buf, meta, sizeof(buf));
345 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
346 		strlcat(buf, "; lang=", sizeof(buf));
347 		strlcat(buf, lang, sizeof(buf));
348 	}
349 
350 	len = strlcat(buf, "\r\n", sizeof(buf));
351 	assert(len < sizeof(buf));
352 
353 	switch (tls_write(c->ctx, buf, len)) {
354 	case -1:
355 		close_conn(pfd, c);
356 		return;
357 	case TLS_WANT_POLLIN:
358 		pfd->events = POLLIN;
359 		return;
360 	case TLS_WANT_POLLOUT:
361 		pfd->events = POLLOUT;
362 		return;
363 	}
364 
365 	log_request(c, buf, sizeof(buf));
366 
367 	/* we don't need a body */
368 	if (c->code != SUCCESS) {
369 		close_conn(pfd, c);
370 		return;
371 	}
372 
373 	/* advance the state machine */
374 	c->state = c->next;
375 	handle(pfd, c);
376 }
377 
378 void
379 start_cgi(const char *spath, const char *relpath, const char *query,
380     struct pollfd *fds, struct client *c)
381 {
382 	char addr[NI_MAXHOST];
383 	const char *ruser, *cissuer, *chash;
384 	int e;
385 
386 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
387 	    addr, sizeof(addr),
388 	    NULL, 0,
389 	    NI_NUMERICHOST);
390 	if (e != 0)
391 		goto err;
392 
393 	if (tls_peer_cert_provided(c->ctx)) {
394 		ruser = tls_peer_cert_subject(c->ctx);
395 		cissuer = tls_peer_cert_issuer(c->ctx);
396 		chash = tls_peer_cert_hash(c->ctx);
397 	} else {
398 		ruser = NULL;
399 		cissuer = NULL;
400 		chash = NULL;
401 	}
402 
403 	if (!send_string(exfd, spath)
404 	    || !send_string(exfd, relpath)
405 	    || !send_string(exfd, query)
406 	    || !send_string(exfd, addr)
407 	    || !send_string(exfd, ruser)
408 	    || !send_string(exfd, cissuer)
409 	    || !send_string(exfd, chash)
410 	    || !send_vhost(exfd, c->host))
411 		goto err;
412 
413 	close(c->fd);
414 	if ((c->fd = recv_fd(exfd)) == -1) {
415 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
416 		return;
417 	}
418 	c->state = S_SENDING_CGI;
419 	cgi_poll_on_child(fds, c);
420 	c->code = -1;
421 	/* handle_cgi(fds, c); */
422 	return;
423 
424 err:
425 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
426 	fatal("cannot talk to the executor process");
427 }
428 
429 void
430 send_file(struct pollfd *fds, struct client *c)
431 {
432 	ssize_t ret, len;
433 
434 	/* ensure the correct state */
435 	c->state = S_SENDING_FILE;
436 
437 	len = (c->buf + c->len) - c->i;
438 
439 	while (len > 0) {
440 		switch (ret = tls_write(c->ctx, c->i, len)) {
441 		case -1:
442 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
443 			close_conn(fds, c);
444 			return;
445 
446 		case TLS_WANT_POLLIN:
447 			fds->events = POLLIN;
448 			return;
449 
450 		case TLS_WANT_POLLOUT:
451 			fds->events = POLLOUT;
452 			return;
453 
454 		default:
455 			c->i += ret;
456 			len -= ret;
457 			break;
458 		}
459 	}
460 
461 	close_conn(fds, c);
462 }
463 
464 void
465 open_dir(struct pollfd *fds, struct client *c)
466 {
467 	size_t len;
468 	int dirfd;
469 	char *before_file;
470 
471 	len = strlen(c->iri.path);
472 	if (len > 0 && !ends_with(c->iri.path, "/")) {
473 		redirect_canonical_dir(fds, c);
474 		return;
475 	}
476 
477 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
478 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
479 	if (!ends_with(c->sbuf, "/"))
480 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
481 	before_file = strchr(c->sbuf, '\0');
482 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
483 	    sizeof(c->sbuf));
484 	if (len >= sizeof(c->sbuf)) {
485 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
486 		return;
487 	}
488 
489 	c->iri.path = c->sbuf;
490 
491 	/* close later unless we have to generate the dir listing */
492 	dirfd = c->fd;
493 	c->fd = -1;
494 
495 	switch (check_path(c, c->iri.path, &c->fd)) {
496 	case FILE_EXECUTABLE:
497 		if (starts_with(c->iri.path, c->host->cgi)) {
498 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
499 			break;
500 		}
501 
502 		/* fallthrough */
503 
504 	case FILE_EXISTS:
505                 load_file(fds, c);
506 		break;
507 
508 	case FILE_DIRECTORY:
509 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
510 		break;
511 
512 	case FILE_MISSING:
513 		*before_file = '\0';
514 
515 		if (!vhost_auto_index(c->host, c->iri.path)) {
516 			start_reply(fds, c, NOT_FOUND, "not found");
517 			break;
518 		}
519 
520 		c->fd = dirfd;
521 		c->next = S_SENDING_DIR;
522 
523 		if ((c->dir = fdopendir(c->fd)) == NULL) {
524 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
525 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
526 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
527 			return;
528 		}
529 		c->off = 0;
530 
531                 start_reply(fds, c, SUCCESS, "text/gemini");
532 		return;
533 
534 	default:
535 		/* unreachable */
536 		abort();
537 	}
538 
539 	close(dirfd);
540 }
541 
542 void
543 redirect_canonical_dir(struct pollfd *fds, struct client *c)
544 {
545 	size_t len;
546 
547 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
548 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
549 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
550 
551 	if (len >= sizeof(c->sbuf)) {
552 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
553 		return;
554 	}
555 
556 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
557 }
558 
559 int
560 read_next_dir_entry(struct client *c)
561 {
562 	struct dirent *d;
563 
564 	do {
565 		errno = 0;
566 		if ((d = readdir(c->dir)) == NULL) {
567 			if (errno != 0)
568 				LOGE(c, "readdir: %s", strerror(errno));
569 			return 0;
570 		}
571 	} while (!strcmp(d->d_name, "."));
572 
573 	/* XXX: url escape */
574 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
575 	    d->d_name, d->d_name);
576 	c->len = strlen(c->sbuf);
577 	c->off = 0;
578 
579 	return 1;
580 }
581 
582 void
583 send_directory_listing(struct pollfd *fds, struct client *c)
584 {
585 	ssize_t r;
586 
587 	while (1) {
588 		if (c->len == 0) {
589 			if (!read_next_dir_entry(c))
590 				goto end;
591 		}
592 
593 		while (c->len > 0) {
594 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
595 			case -1:
596 				goto end;
597 
598 			case TLS_WANT_POLLOUT:
599 				fds->events = POLLOUT;
600 				return;
601 
602 			case TLS_WANT_POLLIN:
603 				fds->events = POLLIN;
604 				return;
605 
606 			default:
607 				c->off += r;
608 				c->len -= r;
609 				break;
610 			}
611 		}
612 	}
613 
614 end:
615 	close_conn(fds, c);
616 }
617 
618 void
619 cgi_poll_on_child(struct pollfd *fds, struct client *c)
620 {
621 	int fd;
622 
623 	if (c->waiting_on_child)
624 		return;
625 	c->waiting_on_child = 1;
626 
627 	fds->events = POLLIN;
628 
629 	fd = fds->fd;
630 	fds->fd = c->fd;
631 	c->fd = fd;
632 }
633 
634 void
635 cgi_poll_on_client(struct pollfd *fds, struct client *c)
636 {
637 	int fd;
638 
639 	if (!c->waiting_on_child)
640 		return;
641 	c->waiting_on_child = 0;
642 
643 	fd = fds->fd;
644 	fds->fd = c->fd;
645 	c->fd = fd;
646 }
647 
648 /* handle the read from the child process.  Return like read(2) */
649 static ssize_t
650 read_from_cgi(struct client *c)
651 {
652 	void	*buf;
653 	size_t	 len;
654 	ssize_t	 r;
655 
656 	/* if we haven't read a whole response line, we want to
657 	 * continue reading. */
658 
659 	if (c->code == -1) {
660 		buf = c->sbuf + c->len;
661 		len = sizeof(c->sbuf) - c->len;
662 	} else {
663 		buf = c->sbuf;
664 		len = sizeof(c->sbuf);
665 	}
666 
667 	r = read(c->fd, buf, len);
668 	if (r == 0 || r == -1)
669 		return r;
670 
671 	c->len += r;
672 	c->off = 0;
673 
674 	if (c->code != -1)
675 		return r;
676 
677 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
678 		c->code = 0;
679 		log_request(c, c->sbuf, c->len);
680 	}
681 
682 	return r;
683 }
684 
685 void
686 handle_cgi(struct pollfd *fds, struct client *c)
687 {
688 	ssize_t r;
689 
690 	/* ensure c->fd is the child and fds->fd the client */
691 	cgi_poll_on_client(fds, c);
692 
693 	while (1) {
694 		if (c->code == -1 || c->len == 0) {
695 			switch (r = read_from_cgi(c)) {
696 			case 0:
697 				goto end;
698 
699 			case -1:
700 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
701 					cgi_poll_on_child(fds, c);
702 					return;
703 				}
704 				goto end;
705 			}
706 		}
707 
708 		if (c->code == -1) {
709 			cgi_poll_on_child(fds, c);
710 			return;
711 		}
712 
713 		while (c->len > 0) {
714 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
715 			case -1:
716 				goto end;
717 
718 			case TLS_WANT_POLLOUT:
719 				fds->events = POLLOUT;
720 				return;
721 
722 			case TLS_WANT_POLLIN:
723 				fds->events = POLLIN;
724 				return;
725 
726 			default:
727                                 c->off += r;
728 				c->len -= r;
729 				break;
730 			}
731 		}
732 	}
733 
734 end:
735 	close_conn(fds, c);
736 }
737 
738 void
739 close_conn(struct pollfd *pfd, struct client *c)
740 {
741 	c->state = S_CLOSING;
742 
743 	switch (tls_close(c->ctx)) {
744 	case TLS_WANT_POLLIN:
745 		pfd->events = POLLIN;
746 		return;
747 	case TLS_WANT_POLLOUT:
748 		pfd->events = POLLOUT;
749 		return;
750 	}
751 
752 	connected_clients--;
753 
754 	tls_free(c->ctx);
755 	c->ctx = NULL;
756 
757 	if (c->buf != MAP_FAILED)
758 		munmap(c->buf, c->len);
759 
760 	if (c->fd != -1)
761 		close(c->fd);
762 
763 	if (c->dir != NULL)
764 		closedir(c->dir);
765 
766 	close(pfd->fd);
767 	pfd->fd = -1;
768 }
769 
770 void
771 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
772 {
773 	int i, fd;
774 	struct sockaddr_storage addr;
775 	socklen_t len;
776 
777 	len = sizeof(addr);
778 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
779 		if (errno == EWOULDBLOCK)
780 			return;
781 		fatal("accept: %s", strerror(errno));
782 	}
783 
784 	mark_nonblock(fd);
785 
786 	for (i = 0; i < MAX_USERS; ++i) {
787 		if (fds[i].fd == -1) {
788 			bzero(&clients[i], sizeof(struct client));
789 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
790 				break; /* goodbye fd! */
791 
792 			fds[i].fd = fd;
793 			fds[i].events = POLLIN;
794 
795 			clients[i].state = S_HANDSHAKE;
796 			clients[i].next = S_SENDING_FILE;
797 			clients[i].fd = -1;
798 			clients[i].waiting_on_child = 0;
799 			clients[i].buf = MAP_FAILED;
800 			clients[i].dir = NULL;
801 			clients[i].addr = addr;
802 
803 			connected_clients++;
804 			return;
805 		}
806 	}
807 
808 	close(fd);
809 }
810 
811 void
812 handle(struct pollfd *fds, struct client *client)
813 {
814 	switch (client->state) {
815 	case S_HANDSHAKE:
816 		handle_handshake(fds, client);
817 		break;
818 
819 	case S_OPEN:
820                 handle_open_conn(fds, client);
821 		break;
822 
823 	case S_INITIALIZING:
824 		start_reply(fds, client, client->code, client->meta);
825                 break;
826 
827 	case S_SENDING_FILE:
828 		send_file(fds, client);
829 		break;
830 
831 	case S_SENDING_DIR:
832 		send_directory_listing(fds, client);
833 		break;
834 
835 	case S_SENDING_CGI:
836 		handle_cgi(fds, client);
837 		break;
838 
839 	case S_CLOSING:
840 		close_conn(fds, client);
841 		break;
842 
843 	default:
844 		/* unreachable */
845 		abort();
846 	}
847 }
848 
849 void
850 loop(struct tls *ctx, int sock4, int sock6)
851 {
852 	int i;
853 	struct client clients[MAX_USERS];
854 	struct pollfd fds[MAX_USERS];
855 
856 	connected_clients = 0;
857 
858 	for (i = 0; i < MAX_USERS; ++i) {
859 		fds[i].fd = -1;
860 		fds[i].events = POLLIN;
861 		bzero(&clients[i], sizeof(struct client));
862 	}
863 
864 	fds[0].fd = sock4;
865 	fds[1].fd = sock6;
866 
867 	for (;;) {
868 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
869 			if (errno == EINTR) {
870                                 fprintf(stderr, "connected clients: %d\n",
871 				    connected_clients);
872 				continue;
873 			}
874 			fatal("poll: %s", strerror(errno));
875 		}
876 
877 		for (i = 0; i < MAX_USERS; i++) {
878 			if (fds[i].revents == 0)
879 				continue;
880 
881 			if (fds[i].revents & (POLLERR|POLLNVAL))
882 				fatal("bad fd %d: %s", fds[i].fd,
883 				    strerror(errno));
884 
885 			if (fds[i].revents & POLLHUP) {
886 				/* fds[i] may be the fd of the stdin
887 				 * of a cgi script that has exited. */
888 				if (!clients[i].waiting_on_child) {
889 					close_conn(&fds[i], &clients[i]);
890 					continue;
891 				}
892 			}
893 
894 			if (fds[i].fd == sock4)
895 				do_accept(sock4, ctx, fds, clients);
896 			else if (fds[i].fd == sock6)
897 				do_accept(sock6, ctx, fds, clients);
898 			else
899 				handle(&fds[i], &clients[i]);
900 		}
901 	}
902 }