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Date:: Wed Jan 27 15:06:15 2021 UTC
Message:: log info about SNI, punycode and matched vhost
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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 || path == 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 	if (v == NULL || path == NULL)
58 		return default_mime;
59 
60 	for (loc = v->locations; loc->match != NULL; ++loc) {
61 		if (!fnmatch(loc->match, path, 0)) {
62 			if (loc->default_mime != NULL)
63 				default_mime = loc->default_mime;
64 		}
65 	}
66 
67 	return default_mime;
68 }
69 
70 const char *
71 vhost_index(struct vhost *v, const char *path)
72 {
73 	struct location *loc;
74 	const char *index = "index.gmi";
75 
76 	if (v == NULL || path == NULL)
77 		return index;
78 
79 	for (loc = v->locations; loc->match != NULL; ++loc) {
80 		if (!fnmatch(loc->match, path, 0)) {
81 			if (loc->index != NULL)
82 				index = loc->index;
83 		}
84 	}
85 
86 	return index;
87 }
88 
89 int
90 vhost_auto_index(struct vhost *v, const char *path)
91 {
92 	struct location *loc;
93 	int auto_index = 0;
94 
95 	for (loc = v->locations; loc->match != NULL; ++loc) {
96 		if (!fnmatch(loc->match, path, 0)) {
97 			if (loc->auto_index)
98 				auto_index = loc->auto_index;
99 		}
100 	}
101 
102 	return auto_index == 1;
103 }
104 
105 int
106 check_path(struct client *c, const char *path, int *fd)
107 {
108 	struct stat sb;
109 	const char *p;
110 	int flags;
111 
112 	assert(path != NULL);
113 
114 	if (*path == '\0')
115 		p = ".";
116 	else if (*path == '/')
117 		/* in send_dir we add an initial / (to be
118 		 * redirect-friendly), but here we want to skip it */
119 		p = path+1;
120 	else
121 		p = path;
122 
123 	flags = O_RDONLY | O_NOFOLLOW;
124 
125 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
126 		return FILE_MISSING;
127 
128 	if (fstat(*fd, &sb) == -1) {
129 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
130 		return FILE_MISSING;
131 	}
132 
133 	if (S_ISDIR(sb.st_mode))
134 		return FILE_DIRECTORY;
135 
136 	if (sb.st_mode & S_IXUSR)
137 		return FILE_EXECUTABLE;
138 
139 	return FILE_EXISTS;
140 }
141 
142 void
143 open_file(struct pollfd *fds, struct client *c)
144 {
145 	switch (check_path(c, c->iri.path, &c->fd)) {
146 	case FILE_EXECUTABLE:
147 		if (starts_with(c->iri.path, c->host->cgi)) {
148 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
149 			return;
150 		}
151 
152 		/* fallthrough */
153 
154 	case FILE_EXISTS:
155 		load_file(fds, c);
156 		return;
157 
158 	case FILE_DIRECTORY:
159 		open_dir(fds, c);
160 		return;
161 
162 	case FILE_MISSING:
163 		if (c->host->cgi != NULL && starts_with(c->iri.path, c->host->cgi)) {
164 			check_for_cgi(c->iri.path, c->iri.query, fds, c);
165 			return;
166 		}
167 		start_reply(fds, c, NOT_FOUND, "not found");
168 		return;
169 
170 	default:
171 		/* unreachable */
172 		abort();
173 	}
174 }
175 
176 void
177 load_file(struct pollfd *fds, struct client *c)
178 {
179 	if ((c->len = filesize(c->fd)) == -1) {
180 		LOGE(c, "failed to get file size for %s", c->iri.path);
181 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
182 		return;
183 	}
184 
185 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
186 		    c->fd, 0)) == MAP_FAILED) {
187 		LOGW(c, "mmap: %s: %s", c->iri.path, strerror(errno));
188 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
189 		return;
190 	}
191 	c->i = c->buf;
192 	c->next = S_SENDING_FILE;
193 	start_reply(fds, c, SUCCESS, mime(c->host, c->iri.path));
194 }
195 
196 /*
197  * the inverse of this algorithm, i.e. starting from the start of the
198  * path + strlen(cgi), and checking if each component, should be
199  * faster.  But it's tedious to write.  This does the opposite: starts
200  * from the end and strip one component at a time, until either an
201  * executable is found or we emptied the path.
202  */
203 void
204 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
205 {
206 	char *end;
207 	end = strchr(path, '\0');
208 
209 	/* NB: assume CGI is enabled and path matches cgi */
210 
211 	while (end > path) {
212 		/* go up one level.  UNIX paths are simple and POSIX
213 		 * dirname, with its ambiguities on if the given path
214 		 * is changed or not, gives me headaches. */
215 		while (*end != '/')
216 			end--;
217 		*end = '\0';
218 
219 		switch (check_path(c, path, &c->fd)) {
220 		case FILE_EXECUTABLE:
221 			start_cgi(path, end+1, query, fds,c);
222 			return;
223 		case FILE_MISSING:
224 			break;
225 		default:
226 			goto err;
227 		}
228 
229 		*end = '/';
230 		end--;
231 	}
232 
233 err:
234 	start_reply(fds, c, NOT_FOUND, "not found");
235 	return;
236 }
237 
238 void
239 mark_nonblock(int fd)
240 {
241 	int flags;
242 
243 	if ((flags = fcntl(fd, F_GETFL)) == -1)
244 		fatal("fcntl(F_GETFL): %s", strerror(errno));
245 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
246 		fatal("fcntl(F_SETFL): %s", strerror(errno));
247 }
248 
249 void
250 handle_handshake(struct pollfd *fds, struct client *c)
251 {
252 	struct vhost *h;
253 	const char *servname;
254 
255 	switch (tls_handshake(c->ctx)) {
256 	case 0:  /* success */
257 	case -1: /* already handshaked */
258 		break;
259 	case TLS_WANT_POLLIN:
260 		fds->events = POLLIN;
261 		return;
262 	case TLS_WANT_POLLOUT:
263 		fds->events = POLLOUT;
264 		return;
265 	default:
266 		/* unreachable */
267 		abort();
268 	}
269 
270 	servname = tls_conn_servername(c->ctx);
271 	puny_decode(servname, c->domain, sizeof(c->domain));
272 
273 	for (h = hosts; h->domain != NULL; ++h) {
274 		if (!fnmatch(h->domain, c->domain, 0))
275 			break;
276 	}
277 
278 	LOGD(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
279 	    servname != NULL ? servname : "(null)",
280 	    c->domain,
281 	    h->domain != NULL ? h->domain : "(null)");
282 
283 	if (h->domain != NULL) {
284 		c->state = S_OPEN;
285 		c->host = h;
286 		handle_open_conn(fds, c);
287 		return;
288 	}
289 
290 	if (servname != NULL)
291 		strncpy(c->req, servname, sizeof(c->req));
292 	else
293 		strncpy(c->req, "null", sizeof(c->req));
294 
295 	start_reply(fds, c, BAD_REQUEST, "Wrong host or missing SNI");
296 }
297 
298 void
299 handle_open_conn(struct pollfd *fds, struct client *c)
300 {
301 	const char *parse_err = "invalid request";
302 	char decoded[DOMAIN_NAME_LEN];
303 
304 	bzero(c->req, sizeof(c->req));
305 	bzero(&c->iri, sizeof(c->iri));
306 
307 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
308 	case -1:
309 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
310 		close_conn(fds, c);
311 		return;
312 
313 	case TLS_WANT_POLLIN:
314 		fds->events = POLLIN;
315 		return;
316 
317 	case TLS_WANT_POLLOUT:
318 		fds->events = POLLOUT;
319 		return;
320 	}
321 
322 	if (!trim_req_iri(c->req, &parse_err)
323 	    || !parse_iri(c->req, &c->iri, &parse_err)) {
324 		LOGI(c, "iri parse error: %s", parse_err);
325 		start_reply(fds, c, BAD_REQUEST, "invalid request");
326 		return;
327 	}
328 
329 	puny_decode(c->iri.host, decoded, sizeof(decoded));
330 
331 	if (c->iri.port_no != conf.port
332 	    || strcmp(c->iri.schema, "gemini")
333 	    || strcmp(decoded, c->domain)) {
334 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
335 		return;
336 	}
337 
338 	open_file(fds, c);
339 }
340 
341 void
342 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
343 {
344 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
345 	const char *lang;
346 	size_t len;
347 
348 	c->code = code;
349 	c->meta = meta;
350 	c->state = S_INITIALIZING;
351 
352 	lang = vhost_lang(c->host, c->iri.path);
353 
354 	snprintf(buf, sizeof(buf), "%d ", code);
355 	strlcat(buf, meta, sizeof(buf));
356 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
357 		strlcat(buf, "; lang=", sizeof(buf));
358 		strlcat(buf, lang, sizeof(buf));
359 	}
360 
361 	len = strlcat(buf, "\r\n", sizeof(buf));
362 	assert(len < sizeof(buf));
363 
364 	switch (tls_write(c->ctx, buf, len)) {
365 	case -1:
366 		close_conn(pfd, c);
367 		return;
368 	case TLS_WANT_POLLIN:
369 		pfd->events = POLLIN;
370 		return;
371 	case TLS_WANT_POLLOUT:
372 		pfd->events = POLLOUT;
373 		return;
374 	}
375 
376 	log_request(c, buf, sizeof(buf));
377 
378 	/* we don't need a body */
379 	if (c->code != SUCCESS) {
380 		close_conn(pfd, c);
381 		return;
382 	}
383 
384 	/* advance the state machine */
385 	c->state = c->next;
386 	handle(pfd, c);
387 }
388 
389 void
390 start_cgi(const char *spath, const char *relpath, const char *query,
391     struct pollfd *fds, struct client *c)
392 {
393 	char addr[NI_MAXHOST];
394 	const char *ruser, *cissuer, *chash;
395 	int e;
396 
397 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
398 	    addr, sizeof(addr),
399 	    NULL, 0,
400 	    NI_NUMERICHOST);
401 	if (e != 0)
402 		goto err;
403 
404 	if (tls_peer_cert_provided(c->ctx)) {
405 		ruser = tls_peer_cert_subject(c->ctx);
406 		cissuer = tls_peer_cert_issuer(c->ctx);
407 		chash = tls_peer_cert_hash(c->ctx);
408 	} else {
409 		ruser = NULL;
410 		cissuer = NULL;
411 		chash = NULL;
412 	}
413 
414 	if (!send_string(exfd, spath)
415 	    || !send_string(exfd, relpath)
416 	    || !send_string(exfd, query)
417 	    || !send_string(exfd, addr)
418 	    || !send_string(exfd, ruser)
419 	    || !send_string(exfd, cissuer)
420 	    || !send_string(exfd, chash)
421 	    || !send_vhost(exfd, c->host))
422 		goto err;
423 
424 	close(c->fd);
425 	if ((c->fd = recv_fd(exfd)) == -1) {
426 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
427 		return;
428 	}
429 	c->state = S_SENDING_CGI;
430 	cgi_poll_on_child(fds, c);
431 	c->code = -1;
432 	/* handle_cgi(fds, c); */
433 	return;
434 
435 err:
436 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
437 	fatal("cannot talk to the executor process");
438 }
439 
440 void
441 send_file(struct pollfd *fds, struct client *c)
442 {
443 	ssize_t ret, len;
444 
445 	/* ensure the correct state */
446 	c->state = S_SENDING_FILE;
447 
448 	len = (c->buf + c->len) - c->i;
449 
450 	while (len > 0) {
451 		switch (ret = tls_write(c->ctx, c->i, len)) {
452 		case -1:
453 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
454 			close_conn(fds, c);
455 			return;
456 
457 		case TLS_WANT_POLLIN:
458 			fds->events = POLLIN;
459 			return;
460 
461 		case TLS_WANT_POLLOUT:
462 			fds->events = POLLOUT;
463 			return;
464 
465 		default:
466 			c->i += ret;
467 			len -= ret;
468 			break;
469 		}
470 	}
471 
472 	close_conn(fds, c);
473 }
474 
475 void
476 open_dir(struct pollfd *fds, struct client *c)
477 {
478 	size_t len;
479 	int dirfd;
480 	char *before_file;
481 
482 	len = strlen(c->iri.path);
483 	if (len > 0 && !ends_with(c->iri.path, "/")) {
484 		redirect_canonical_dir(fds, c);
485 		return;
486 	}
487 
488 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
489 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
490 	if (!ends_with(c->sbuf, "/"))
491 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
492 	before_file = strchr(c->sbuf, '\0');
493 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
494 	    sizeof(c->sbuf));
495 	if (len >= sizeof(c->sbuf)) {
496 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
497 		return;
498 	}
499 
500 	c->iri.path = c->sbuf;
501 
502 	/* close later unless we have to generate the dir listing */
503 	dirfd = c->fd;
504 	c->fd = -1;
505 
506 	switch (check_path(c, c->iri.path, &c->fd)) {
507 	case FILE_EXECUTABLE:
508 		if (starts_with(c->iri.path, c->host->cgi)) {
509 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
510 			break;
511 		}
512 
513 		/* fallthrough */
514 
515 	case FILE_EXISTS:
516                 load_file(fds, c);
517 		break;
518 
519 	case FILE_DIRECTORY:
520 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
521 		break;
522 
523 	case FILE_MISSING:
524 		*before_file = '\0';
525 
526 		if (!vhost_auto_index(c->host, c->iri.path)) {
527 			start_reply(fds, c, NOT_FOUND, "not found");
528 			break;
529 		}
530 
531 		c->fd = dirfd;
532 		c->next = S_SENDING_DIR;
533 
534 		if ((c->dir = fdopendir(c->fd)) == NULL) {
535 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
536 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
537 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
538 			return;
539 		}
540 		c->off = 0;
541 
542                 start_reply(fds, c, SUCCESS, "text/gemini");
543 		return;
544 
545 	default:
546 		/* unreachable */
547 		abort();
548 	}
549 
550 	close(dirfd);
551 }
552 
553 void
554 redirect_canonical_dir(struct pollfd *fds, struct client *c)
555 {
556 	size_t len;
557 
558 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
559 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
560 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
561 
562 	if (len >= sizeof(c->sbuf)) {
563 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
564 		return;
565 	}
566 
567 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
568 }
569 
570 int
571 read_next_dir_entry(struct client *c)
572 {
573 	struct dirent *d;
574 
575 	do {
576 		errno = 0;
577 		if ((d = readdir(c->dir)) == NULL) {
578 			if (errno != 0)
579 				LOGE(c, "readdir: %s", strerror(errno));
580 			return 0;
581 		}
582 	} while (!strcmp(d->d_name, "."));
583 
584 	/* XXX: url escape */
585 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
586 	    d->d_name, d->d_name);
587 	c->len = strlen(c->sbuf);
588 	c->off = 0;
589 
590 	return 1;
591 }
592 
593 void
594 send_directory_listing(struct pollfd *fds, struct client *c)
595 {
596 	ssize_t r;
597 
598 	while (1) {
599 		if (c->len == 0) {
600 			if (!read_next_dir_entry(c))
601 				goto end;
602 		}
603 
604 		while (c->len > 0) {
605 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
606 			case -1:
607 				goto end;
608 
609 			case TLS_WANT_POLLOUT:
610 				fds->events = POLLOUT;
611 				return;
612 
613 			case TLS_WANT_POLLIN:
614 				fds->events = POLLIN;
615 				return;
616 
617 			default:
618 				c->off += r;
619 				c->len -= r;
620 				break;
621 			}
622 		}
623 	}
624 
625 end:
626 	close_conn(fds, c);
627 }
628 
629 void
630 cgi_poll_on_child(struct pollfd *fds, struct client *c)
631 {
632 	int fd;
633 
634 	if (c->waiting_on_child)
635 		return;
636 	c->waiting_on_child = 1;
637 
638 	fds->events = POLLIN;
639 
640 	fd = fds->fd;
641 	fds->fd = c->fd;
642 	c->fd = fd;
643 }
644 
645 void
646 cgi_poll_on_client(struct pollfd *fds, struct client *c)
647 {
648 	int fd;
649 
650 	if (!c->waiting_on_child)
651 		return;
652 	c->waiting_on_child = 0;
653 
654 	fd = fds->fd;
655 	fds->fd = c->fd;
656 	c->fd = fd;
657 }
658 
659 /* handle the read from the child process.  Return like read(2) */
660 static ssize_t
661 read_from_cgi(struct client *c)
662 {
663 	void	*buf;
664 	size_t	 len;
665 	ssize_t	 r;
666 
667 	/* if we haven't read a whole response line, we want to
668 	 * continue reading. */
669 
670 	if (c->code == -1) {
671 		buf = c->sbuf + c->len;
672 		len = sizeof(c->sbuf) - c->len;
673 	} else {
674 		buf = c->sbuf;
675 		len = sizeof(c->sbuf);
676 	}
677 
678 	r = read(c->fd, buf, len);
679 	if (r == 0 || r == -1)
680 		return r;
681 
682 	c->len += r;
683 	c->off = 0;
684 
685 	if (c->code != -1)
686 		return r;
687 
688 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
689 		c->code = 0;
690 		log_request(c, c->sbuf, c->len);
691 	}
692 
693 	return r;
694 }
695 
696 void
697 handle_cgi(struct pollfd *fds, struct client *c)
698 {
699 	ssize_t r;
700 
701 	/* ensure c->fd is the child and fds->fd the client */
702 	cgi_poll_on_client(fds, c);
703 
704 	while (1) {
705 		if (c->code == -1 || c->len == 0) {
706 			switch (r = read_from_cgi(c)) {
707 			case 0:
708 				goto end;
709 
710 			case -1:
711 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
712 					cgi_poll_on_child(fds, c);
713 					return;
714 				}
715 				goto end;
716 			}
717 		}
718 
719 		if (c->code == -1) {
720 			cgi_poll_on_child(fds, c);
721 			return;
722 		}
723 
724 		while (c->len > 0) {
725 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
726 			case -1:
727 				goto end;
728 
729 			case TLS_WANT_POLLOUT:
730 				fds->events = POLLOUT;
731 				return;
732 
733 			case TLS_WANT_POLLIN:
734 				fds->events = POLLIN;
735 				return;
736 
737 			default:
738                                 c->off += r;
739 				c->len -= r;
740 				break;
741 			}
742 		}
743 	}
744 
745 end:
746 	close_conn(fds, c);
747 }
748 
749 void
750 close_conn(struct pollfd *pfd, struct client *c)
751 {
752 	c->state = S_CLOSING;
753 
754 	switch (tls_close(c->ctx)) {
755 	case TLS_WANT_POLLIN:
756 		pfd->events = POLLIN;
757 		return;
758 	case TLS_WANT_POLLOUT:
759 		pfd->events = POLLOUT;
760 		return;
761 	}
762 
763 	connected_clients--;
764 
765 	tls_free(c->ctx);
766 	c->ctx = NULL;
767 
768 	if (c->buf != MAP_FAILED)
769 		munmap(c->buf, c->len);
770 
771 	if (c->fd != -1)
772 		close(c->fd);
773 
774 	if (c->dir != NULL)
775 		closedir(c->dir);
776 
777 	close(pfd->fd);
778 	pfd->fd = -1;
779 }
780 
781 void
782 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
783 {
784 	int i, fd;
785 	struct sockaddr_storage addr;
786 	socklen_t len;
787 
788 	len = sizeof(addr);
789 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
790 		if (errno == EWOULDBLOCK)
791 			return;
792 		fatal("accept: %s", strerror(errno));
793 	}
794 
795 	mark_nonblock(fd);
796 
797 	for (i = 0; i < MAX_USERS; ++i) {
798 		if (fds[i].fd == -1) {
799 			bzero(&clients[i], sizeof(struct client));
800 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
801 				break; /* goodbye fd! */
802 
803 			fds[i].fd = fd;
804 			fds[i].events = POLLIN;
805 
806 			clients[i].state = S_HANDSHAKE;
807 			clients[i].next = S_SENDING_FILE;
808 			clients[i].fd = -1;
809 			clients[i].waiting_on_child = 0;
810 			clients[i].buf = MAP_FAILED;
811 			clients[i].dir = NULL;
812 			clients[i].addr = addr;
813 
814 			connected_clients++;
815 			return;
816 		}
817 	}
818 
819 	close(fd);
820 }
821 
822 void
823 handle(struct pollfd *fds, struct client *client)
824 {
825 	switch (client->state) {
826 	case S_HANDSHAKE:
827 		handle_handshake(fds, client);
828 		break;
829 
830 	case S_OPEN:
831                 handle_open_conn(fds, client);
832 		break;
833 
834 	case S_INITIALIZING:
835 		start_reply(fds, client, client->code, client->meta);
836                 break;
837 
838 	case S_SENDING_FILE:
839 		send_file(fds, client);
840 		break;
841 
842 	case S_SENDING_DIR:
843 		send_directory_listing(fds, client);
844 		break;
845 
846 	case S_SENDING_CGI:
847 		handle_cgi(fds, client);
848 		break;
849 
850 	case S_CLOSING:
851 		close_conn(fds, client);
852 		break;
853 
854 	default:
855 		/* unreachable */
856 		abort();
857 	}
858 }
859 
860 void
861 loop(struct tls *ctx, int sock4, int sock6)
862 {
863 	int i;
864 	struct client clients[MAX_USERS];
865 	struct pollfd fds[MAX_USERS];
866 
867 	connected_clients = 0;
868 
869 	for (i = 0; i < MAX_USERS; ++i) {
870 		fds[i].fd = -1;
871 		fds[i].events = POLLIN;
872 		bzero(&clients[i], sizeof(struct client));
873 	}
874 
875 	fds[0].fd = sock4;
876 	fds[1].fd = sock6;
877 
878 	for (;;) {
879 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
880 			if (errno == EINTR) {
881                                 fprintf(stderr, "connected clients: %d\n",
882 				    connected_clients);
883 				continue;
884 			}
885 			fatal("poll: %s", strerror(errno));
886 		}
887 
888 		for (i = 0; i < MAX_USERS; i++) {
889 			if (fds[i].revents == 0)
890 				continue;
891 
892 			if (fds[i].revents & (POLLERR|POLLNVAL))
893 				fatal("bad fd %d: %s", fds[i].fd,
894 				    strerror(errno));
895 
896 			if (fds[i].revents & POLLHUP) {
897 				/* fds[i] may be the fd of the stdin
898 				 * of a cgi script that has exited. */
899 				if (!clients[i].waiting_on_child) {
900 					close_conn(&fds[i], &clients[i]);
901 					continue;
902 				}
903 			}
904 
905 			if (fds[i].fd == sock4)
906 				do_accept(sock4, ctx, fds, clients);
907 			else if (fds[i].fd == sock6)
908 				do_accept(sock6, ctx, fds, clients);
909 			else
910 				handle(&fds[i], &clients[i]);
911 		}
912 	}
913 }