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Date:: Wed Jan 27 10:47:49 2021 UTC
Message:: initial punycode support
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 	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_iri(c->req, &c->iri, &parse_err)) {
312 		start_reply(fds, c, BAD_REQUEST, parse_err);
313 		return;
314 	}
315 
316 	puny_decode(c->iri.host, decoded, sizeof(decoded));
317 
318 	if (c->iri.port_no != conf.port
319 	    || strcmp(c->iri.schema, "gemini")
320 	    || strcmp(decoded, c->domain)) {
321 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
322 		return;
323 	}
324 
325 	open_file(fds, c);
326 }
327 
328 void
329 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
330 {
331 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
332 	const char *lang;
333 	size_t len;
334 
335 	c->code = code;
336 	c->meta = meta;
337 	c->state = S_INITIALIZING;
338 
339 	lang = vhost_lang(c->host, c->iri.path);
340 
341 	snprintf(buf, sizeof(buf), "%d ", code);
342 	strlcat(buf, meta, sizeof(buf));
343 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
344 		strlcat(buf, "; lang=", sizeof(buf));
345 		strlcat(buf, lang, sizeof(buf));
346 	}
347 
348 	len = strlcat(buf, "\r\n", sizeof(buf));
349 	assert(len < sizeof(buf));
350 
351 	switch (tls_write(c->ctx, buf, len)) {
352 	case -1:
353 		close_conn(pfd, c);
354 		return;
355 	case TLS_WANT_POLLIN:
356 		pfd->events = POLLIN;
357 		return;
358 	case TLS_WANT_POLLOUT:
359 		pfd->events = POLLOUT;
360 		return;
361 	}
362 
363 	log_request(c, buf, sizeof(buf));
364 
365 	/* we don't need a body */
366 	if (c->code != SUCCESS) {
367 		close_conn(pfd, c);
368 		return;
369 	}
370 
371 	/* advance the state machine */
372 	c->state = c->next;
373 	handle(pfd, c);
374 }
375 
376 void
377 start_cgi(const char *spath, const char *relpath, const char *query,
378     struct pollfd *fds, struct client *c)
379 {
380 	char addr[NI_MAXHOST];
381 	const char *ruser, *cissuer, *chash;
382 	int e;
383 
384 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
385 	    addr, sizeof(addr),
386 	    NULL, 0,
387 	    NI_NUMERICHOST);
388 	if (e != 0)
389 		goto err;
390 
391 	if (tls_peer_cert_provided(c->ctx)) {
392 		ruser = tls_peer_cert_subject(c->ctx);
393 		cissuer = tls_peer_cert_issuer(c->ctx);
394 		chash = tls_peer_cert_hash(c->ctx);
395 	} else {
396 		ruser = NULL;
397 		cissuer = NULL;
398 		chash = NULL;
399 	}
400 
401 	if (!send_string(exfd, spath)
402 	    || !send_string(exfd, relpath)
403 	    || !send_string(exfd, query)
404 	    || !send_string(exfd, addr)
405 	    || !send_string(exfd, ruser)
406 	    || !send_string(exfd, cissuer)
407 	    || !send_string(exfd, chash)
408 	    || !send_vhost(exfd, c->host))
409 		goto err;
410 
411 	close(c->fd);
412 	if ((c->fd = recv_fd(exfd)) == -1) {
413 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
414 		return;
415 	}
416 	c->state = S_SENDING_CGI;
417 	cgi_poll_on_child(fds, c);
418 	c->code = -1;
419 	/* handle_cgi(fds, c); */
420 	return;
421 
422 err:
423 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
424 	fatal("cannot talk to the executor process");
425 }
426 
427 void
428 send_file(struct pollfd *fds, struct client *c)
429 {
430 	ssize_t ret, len;
431 
432 	/* ensure the correct state */
433 	c->state = S_SENDING_FILE;
434 
435 	len = (c->buf + c->len) - c->i;
436 
437 	while (len > 0) {
438 		switch (ret = tls_write(c->ctx, c->i, len)) {
439 		case -1:
440 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
441 			close_conn(fds, c);
442 			return;
443 
444 		case TLS_WANT_POLLIN:
445 			fds->events = POLLIN;
446 			return;
447 
448 		case TLS_WANT_POLLOUT:
449 			fds->events = POLLOUT;
450 			return;
451 
452 		default:
453 			c->i += ret;
454 			len -= ret;
455 			break;
456 		}
457 	}
458 
459 	close_conn(fds, c);
460 }
461 
462 void
463 open_dir(struct pollfd *fds, struct client *c)
464 {
465 	size_t len;
466 	int dirfd;
467 	char *before_file;
468 
469 	len = strlen(c->iri.path);
470 	if (len > 0 && !ends_with(c->iri.path, "/")) {
471 		redirect_canonical_dir(fds, c);
472 		return;
473 	}
474 
475 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
476 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
477 	if (!ends_with(c->sbuf, "/"))
478 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
479 	before_file = strchr(c->sbuf, '\0');
480 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
481 	    sizeof(c->sbuf));
482 	if (len >= sizeof(c->sbuf)) {
483 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
484 		return;
485 	}
486 
487 	c->iri.path = c->sbuf;
488 
489 	/* close later unless we have to generate the dir listing */
490 	dirfd = c->fd;
491 	c->fd = -1;
492 
493 	switch (check_path(c, c->iri.path, &c->fd)) {
494 	case FILE_EXECUTABLE:
495 		if (starts_with(c->iri.path, c->host->cgi)) {
496 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
497 			break;
498 		}
499 
500 		/* fallthrough */
501 
502 	case FILE_EXISTS:
503                 load_file(fds, c);
504 		break;
505 
506 	case FILE_DIRECTORY:
507 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
508 		break;
509 
510 	case FILE_MISSING:
511 		*before_file = '\0';
512 
513 		if (!vhost_auto_index(c->host, c->iri.path)) {
514 			start_reply(fds, c, NOT_FOUND, "not found");
515 			break;
516 		}
517 
518 		c->fd = dirfd;
519 		c->next = S_SENDING_DIR;
520 
521 		if ((c->dir = fdopendir(c->fd)) == NULL) {
522 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
523 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
524 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
525 			return;
526 		}
527 		c->off = 0;
528 
529                 start_reply(fds, c, SUCCESS, "text/gemini");
530 		return;
531 
532 	default:
533 		/* unreachable */
534 		abort();
535 	}
536 
537 	close(dirfd);
538 }
539 
540 void
541 redirect_canonical_dir(struct pollfd *fds, struct client *c)
542 {
543 	size_t len;
544 
545 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
546 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
547 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
548 
549 	if (len >= sizeof(c->sbuf)) {
550 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
551 		return;
552 	}
553 
554 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
555 }
556 
557 int
558 read_next_dir_entry(struct client *c)
559 {
560 	struct dirent *d;
561 
562 	do {
563 		errno = 0;
564 		if ((d = readdir(c->dir)) == NULL) {
565 			if (errno != 0)
566 				LOGE(c, "readdir: %s", strerror(errno));
567 			return 0;
568 		}
569 	} while (!strcmp(d->d_name, "."));
570 
571 	/* XXX: url escape */
572 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
573 	    d->d_name, d->d_name);
574 	c->len = strlen(c->sbuf);
575 	c->off = 0;
576 
577 	return 1;
578 }
579 
580 void
581 send_directory_listing(struct pollfd *fds, struct client *c)
582 {
583 	ssize_t r;
584 
585 	while (1) {
586 		if (c->len == 0) {
587 			if (!read_next_dir_entry(c))
588 				goto end;
589 		}
590 
591 		while (c->len > 0) {
592 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
593 			case -1:
594 				goto end;
595 
596 			case TLS_WANT_POLLOUT:
597 				fds->events = POLLOUT;
598 				return;
599 
600 			case TLS_WANT_POLLIN:
601 				fds->events = POLLIN;
602 				return;
603 
604 			default:
605 				c->off += r;
606 				c->len -= r;
607 				break;
608 			}
609 		}
610 	}
611 
612 end:
613 	close_conn(fds, c);
614 }
615 
616 void
617 cgi_poll_on_child(struct pollfd *fds, struct client *c)
618 {
619 	int fd;
620 
621 	if (c->waiting_on_child)
622 		return;
623 	c->waiting_on_child = 1;
624 
625 	fds->events = POLLIN;
626 
627 	fd = fds->fd;
628 	fds->fd = c->fd;
629 	c->fd = fd;
630 }
631 
632 void
633 cgi_poll_on_client(struct pollfd *fds, struct client *c)
634 {
635 	int fd;
636 
637 	if (!c->waiting_on_child)
638 		return;
639 	c->waiting_on_child = 0;
640 
641 	fd = fds->fd;
642 	fds->fd = c->fd;
643 	c->fd = fd;
644 }
645 
646 /* handle the read from the child process.  Return like read(2) */
647 static ssize_t
648 read_from_cgi(struct client *c)
649 {
650 	void	*buf;
651 	size_t	 len;
652 	ssize_t	 r;
653 
654 	/* if we haven't read a whole response line, we want to
655 	 * continue reading. */
656 
657 	if (c->code == -1) {
658 		buf = c->sbuf + c->len;
659 		len = sizeof(c->sbuf) - c->len;
660 	} else {
661 		buf = c->sbuf;
662 		len = sizeof(c->sbuf);
663 	}
664 
665 	r = read(c->fd, buf, len);
666 	if (r == 0 || r == -1)
667 		return r;
668 
669 	c->len += r;
670 	c->off = 0;
671 
672 	if (c->code != -1)
673 		return r;
674 
675 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
676 		c->code = 0;
677 		log_request(c, c->sbuf, c->len);
678 	}
679 
680 	return r;
681 }
682 
683 void
684 handle_cgi(struct pollfd *fds, struct client *c)
685 {
686 	ssize_t r;
687 
688 	/* ensure c->fd is the child and fds->fd the client */
689 	cgi_poll_on_client(fds, c);
690 
691 	while (1) {
692 		if (c->code == -1 || c->len == 0) {
693 			switch (r = read_from_cgi(c)) {
694 			case 0:
695 				goto end;
696 
697 			case -1:
698 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
699 					cgi_poll_on_child(fds, c);
700 					return;
701 				}
702 				goto end;
703 			}
704 		}
705 
706 		if (c->code == -1) {
707 			cgi_poll_on_child(fds, c);
708 			return;
709 		}
710 
711 		while (c->len > 0) {
712 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
713 			case -1:
714 				goto end;
715 
716 			case TLS_WANT_POLLOUT:
717 				fds->events = POLLOUT;
718 				return;
719 
720 			case TLS_WANT_POLLIN:
721 				fds->events = POLLIN;
722 				return;
723 
724 			default:
725                                 c->off += r;
726 				c->len -= r;
727 				break;
728 			}
729 		}
730 	}
731 
732 end:
733 	close_conn(fds, c);
734 }
735 
736 void
737 close_conn(struct pollfd *pfd, struct client *c)
738 {
739 	c->state = S_CLOSING;
740 
741 	switch (tls_close(c->ctx)) {
742 	case TLS_WANT_POLLIN:
743 		pfd->events = POLLIN;
744 		return;
745 	case TLS_WANT_POLLOUT:
746 		pfd->events = POLLOUT;
747 		return;
748 	}
749 
750 	connected_clients--;
751 
752 	tls_free(c->ctx);
753 	c->ctx = NULL;
754 
755 	if (c->buf != MAP_FAILED)
756 		munmap(c->buf, c->len);
757 
758 	if (c->fd != -1)
759 		close(c->fd);
760 
761 	if (c->dir != NULL)
762 		closedir(c->dir);
763 
764 	close(pfd->fd);
765 	pfd->fd = -1;
766 }
767 
768 void
769 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
770 {
771 	int i, fd;
772 	struct sockaddr_storage addr;
773 	socklen_t len;
774 
775 	len = sizeof(addr);
776 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
777 		if (errno == EWOULDBLOCK)
778 			return;
779 		fatal("accept: %s", strerror(errno));
780 	}
781 
782 	mark_nonblock(fd);
783 
784 	for (i = 0; i < MAX_USERS; ++i) {
785 		if (fds[i].fd == -1) {
786 			bzero(&clients[i], sizeof(struct client));
787 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
788 				break; /* goodbye fd! */
789 
790 			fds[i].fd = fd;
791 			fds[i].events = POLLIN;
792 
793 			clients[i].state = S_HANDSHAKE;
794 			clients[i].next = S_SENDING_FILE;
795 			clients[i].fd = -1;
796 			clients[i].waiting_on_child = 0;
797 			clients[i].buf = MAP_FAILED;
798 			clients[i].dir = NULL;
799 			clients[i].addr = addr;
800 
801 			connected_clients++;
802 			return;
803 		}
804 	}
805 
806 	close(fd);
807 }
808 
809 void
810 handle(struct pollfd *fds, struct client *client)
811 {
812 	switch (client->state) {
813 	case S_HANDSHAKE:
814 		handle_handshake(fds, client);
815 		break;
816 
817 	case S_OPEN:
818                 handle_open_conn(fds, client);
819 		break;
820 
821 	case S_INITIALIZING:
822 		start_reply(fds, client, client->code, client->meta);
823                 break;
824 
825 	case S_SENDING_FILE:
826 		send_file(fds, client);
827 		break;
828 
829 	case S_SENDING_DIR:
830 		send_directory_listing(fds, client);
831 		break;
832 
833 	case S_SENDING_CGI:
834 		handle_cgi(fds, client);
835 		break;
836 
837 	case S_CLOSING:
838 		close_conn(fds, client);
839 		break;
840 
841 	default:
842 		/* unreachable */
843 		abort();
844 	}
845 }
846 
847 void
848 loop(struct tls *ctx, int sock4, int sock6)
849 {
850 	int i;
851 	struct client clients[MAX_USERS];
852 	struct pollfd fds[MAX_USERS];
853 
854 	connected_clients = 0;
855 
856 	for (i = 0; i < MAX_USERS; ++i) {
857 		fds[i].fd = -1;
858 		fds[i].events = POLLIN;
859 		bzero(&clients[i], sizeof(struct client));
860 	}
861 
862 	fds[0].fd = sock4;
863 	fds[1].fd = sock6;
864 
865 	for (;;) {
866 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
867 			if (errno == EINTR) {
868                                 fprintf(stderr, "connected clients: %d\n",
869 				    connected_clients);
870 				continue;
871 			}
872 			fatal("poll: %s", strerror(errno));
873 		}
874 
875 		for (i = 0; i < MAX_USERS; i++) {
876 			if (fds[i].revents == 0)
877 				continue;
878 
879 			if (fds[i].revents & (POLLERR|POLLNVAL))
880 				fatal("bad fd %d: %s", fds[i].fd,
881 				    strerror(errno));
882 
883 			if (fds[i].revents & POLLHUP) {
884 				/* fds[i] may be the fd of the stdin
885 				 * of a cgi script that has exited. */
886 				if (!clients[i].waiting_on_child) {
887 					close_conn(&fds[i], &clients[i]);
888 					continue;
889 				}
890 			}
891 
892 			if (fds[i].fd == sock4)
893 				do_accept(sock4, ctx, fds, clients);
894 			else if (fds[i].fd == sock6)
895 				do_accept(sock6, ctx, fds, clients);
896 			else
897 				handle(&fds[i], &clients[i]);
898 		}
899 	}
900 }