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Date:: Thu Feb 4 13:23:15 2021 UTC
Message:: reload configuration on SIGHUP
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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 <limits.h>
27 #include <string.h>
28 
29 #include "gmid.h"
30 
31 int connected_clients;
32 
33 static int	 check_path(struct client*, const char*, int*);
34 static void	 open_file(struct pollfd*, struct client*);
35 static void	 load_file(struct pollfd*, struct client*);
36 static void	 check_for_cgi(struct pollfd*, struct client*);
37 static void	 handle_handshake(struct pollfd*, struct client*);
38 static void	 handle_open_conn(struct pollfd*, struct client*);
39 static void	 start_reply(struct pollfd*, struct client*, int, const char*);
40 static void	 handle_start_reply(struct pollfd*, struct client*);
41 static void	 start_cgi(const char*, const char*, struct pollfd*, struct client*);
42 static void	 send_file(struct pollfd*, struct client*);
43 static void	 open_dir(struct pollfd*, struct client*);
44 static void	 redirect_canonical_dir(struct pollfd*, struct client*);
45 static void	 enter_handle_dirlist(struct pollfd*, struct client*);
46 static void	 handle_dirlist(struct pollfd*, struct client*);
47 static int 	 read_next_dir_entry(struct client*);
48 static void	 send_directory_listing(struct pollfd*, struct client*);
49 static void	 cgi_poll_on_child(struct pollfd*, struct client*);
50 static void	 cgi_poll_on_client(struct pollfd*, struct client*);
51 static void	 handle_cgi_reply(struct pollfd*, struct client*);
52 static void	 handle_cgi(struct pollfd*, struct client*);
53 static void	 close_conn(struct pollfd*, struct client*);
54 static void	 do_accept(int, struct tls*, struct pollfd*, struct client*);
55 
56 const char *
57 vhost_lang(struct vhost *v, const char *path)
58 {
59 	struct location *loc;
60 
61 	if (v == NULL || path == NULL)
62 		return NULL;
63 
64 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
65 		if (!fnmatch(loc->match, path, 0)) {
66 			if (loc->lang != NULL)
67 				return loc->lang;
68 		}
69 	}
70 
71 	return v->locations[0].lang;
72 }
73 
74 const char *
75 vhost_default_mime(struct vhost *v, const char *path)
76 {
77 	struct location *loc;
78 	const char *default_mime = "application/octet-stream";
79 
80 	if (v == NULL || path == NULL)
81 		return default_mime;
82 
83 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
84 		if (!fnmatch(loc->match, path, 0)) {
85 			if (loc->default_mime != NULL)
86 				return loc->default_mime;
87 		}
88 	}
89 
90 	if (v->locations[0].default_mime != NULL)
91 		return v->locations[0].default_mime;
92 	return default_mime;
93 }
94 
95 const char *
96 vhost_index(struct vhost *v, const char *path)
97 {
98 	struct location *loc;
99 	const char *index = "index.gmi";
100 
101 	if (v == NULL || path == NULL)
102 		return index;
103 
104 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
105 		if (!fnmatch(loc->match, path, 0)) {
106 			if (loc->index != NULL)
107 				return loc->index;
108 		}
109 	}
110 
111 	if (v->locations[0].index != NULL)
112 		return v->locations[0].index;
113 	return index;
114 }
115 
116 int
117 vhost_auto_index(struct vhost *v, const char *path)
118 {
119 	struct location *loc;
120 
121 	if (v == NULL || path == NULL)
122 		return 0;
123 
124 	for (loc = v->locations; loc->match != NULL; ++loc) {
125 		if (!fnmatch(loc->match, path, 0)) {
126 			if (loc->auto_index != 0)
127 				return loc->auto_index == 1;
128 		}
129 	}
130 
131 	return v->locations[0].auto_index == 1;
132 }
133 
134 static int
135 check_path(struct client *c, const char *path, int *fd)
136 {
137 	struct stat sb;
138 	const char *p;
139 	int flags;
140 
141 	assert(path != NULL);
142 
143 	if (*path == '\0')
144 		p = ".";
145 	else if (*path == '/')
146 		/* in send_dir we add an initial / (to be
147 		 * redirect-friendly), but here we want to skip it */
148 		p = path+1;
149 	else
150 		p = path;
151 
152 	flags = O_RDONLY | O_NOFOLLOW;
153 
154 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
155 		return FILE_MISSING;
156 
157 	if (fstat(*fd, &sb) == -1) {
158 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
159 		return FILE_MISSING;
160 	}
161 
162 	if (S_ISDIR(sb.st_mode))
163 		return FILE_DIRECTORY;
164 
165 	if (sb.st_mode & S_IXUSR)
166 		return FILE_EXECUTABLE;
167 
168 	return FILE_EXISTS;
169 }
170 
171 static void
172 open_file(struct pollfd *fds, struct client *c)
173 {
174 	switch (check_path(c, c->iri.path, &c->fd)) {
175 	case FILE_EXECUTABLE:
176 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
177 			start_cgi(c->iri.path, "", fds, c);
178 			return;
179 		}
180 
181 		/* fallthrough */
182 
183 	case FILE_EXISTS:
184 		load_file(fds, c);
185 		return;
186 
187 	case FILE_DIRECTORY:
188 		open_dir(fds, c);
189 		return;
190 
191 	case FILE_MISSING:
192 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
193 			check_for_cgi(fds, c);
194 			return;
195 		}
196 		start_reply(fds, c, NOT_FOUND, "not found");
197 		return;
198 
199 	default:
200 		/* unreachable */
201 		abort();
202 	}
203 }
204 
205 static void
206 load_file(struct pollfd *fds, struct client *c)
207 {
208 	if ((c->len = filesize(c->fd)) == -1) {
209 		LOGE(c, "failed to get file size for %s: %s",
210 		    c->iri.path, strerror(errno));
211 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
212 		return;
213 	}
214 
215 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
216 		    c->fd, 0)) == MAP_FAILED) {
217 		LOGW(c, "mmap: %s: %s", c->iri.path, strerror(errno));
218 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
219 		return;
220 	}
221 	c->i = c->buf;
222 	c->next = send_file;
223 	start_reply(fds, c, SUCCESS, mime(c->host, c->iri.path));
224 }
225 
226 /*
227  * the inverse of this algorithm, i.e. starting from the start of the
228  * path + strlen(cgi), and checking if each component, should be
229  * faster.  But it's tedious to write.  This does the opposite: starts
230  * from the end and strip one component at a time, until either an
231  * executable is found or we emptied the path.
232  */
233 static void
234 check_for_cgi(struct pollfd *fds, struct client *c)
235 {
236 	char path[PATH_MAX];
237 	char *end;
238 
239 	strlcpy(path, c->iri.path, sizeof(path));
240 	end = strchr(path, '\0');
241 
242 	/* NB: assume CGI is enabled and path matches cgi */
243 
244 	while (end > path) {
245 		/* go up one level.  UNIX paths are simple and POSIX
246 		 * dirname, with its ambiguities on if the given path
247 		 * is changed or not, gives me headaches. */
248 		while (*end != '/')
249 			end--;
250 		*end = '\0';
251 
252 		switch (check_path(c, path, &c->fd)) {
253 		case FILE_EXECUTABLE:
254 			start_cgi(path, end+1, fds, c);
255 			return;
256 		case FILE_MISSING:
257 			break;
258 		default:
259 			goto err;
260 		}
261 
262 		*end = '/';
263 		end--;
264 	}
265 
266 err:
267 	start_reply(fds, c, NOT_FOUND, "not found");
268 	return;
269 }
270 
271 void
272 mark_nonblock(int fd)
273 {
274 	int flags;
275 
276 	if ((flags = fcntl(fd, F_GETFL)) == -1)
277 		fatal("fcntl(F_GETFL): %s", strerror(errno));
278 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
279 		fatal("fcntl(F_SETFL): %s", strerror(errno));
280 }
281 
282 static void
283 handle_handshake(struct pollfd *fds, struct client *c)
284 {
285 	struct vhost *h;
286 	const char *servname;
287 	const char *parse_err = "unknown error";
288 
289 	switch (tls_handshake(c->ctx)) {
290 	case 0:  /* success */
291 	case -1: /* already handshaked */
292 		break;
293 	case TLS_WANT_POLLIN:
294 		fds->events = POLLIN;
295 		return;
296 	case TLS_WANT_POLLOUT:
297 		fds->events = POLLOUT;
298 		return;
299 	default:
300 		/* unreachable */
301 		abort();
302 	}
303 
304 	servname = tls_conn_servername(c->ctx);
305 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
306 		LOGI(c, "%s", parse_err);
307 		goto err;
308 	}
309 
310 	for (h = hosts; h->domain != NULL; ++h) {
311 		if (!fnmatch(h->domain, c->domain, 0))
312 			break;
313 	}
314 
315 	/* LOGD(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"", */
316 	/*     servname != NULL ? servname : "(null)", */
317 	/*     c->domain, */
318 	/*     h->domain != NULL ? h->domain : "(null)"); */
319 
320 	if (h->domain != NULL) {
321 		c->host = h;
322 		c->state = handle_open_conn;
323 		c->state(fds, c);
324 		return;
325 	}
326 
327 err:
328 	if (servname != NULL)
329 		strncpy(c->req, servname, sizeof(c->req));
330 	else
331 		strncpy(c->req, "null", sizeof(c->req));
332 
333 	start_reply(fds, c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
334 }
335 
336 static void
337 handle_open_conn(struct pollfd *fds, struct client *c)
338 {
339 	const char *parse_err = "invalid request";
340 	char decoded[DOMAIN_NAME_LEN];
341 
342 	bzero(c->req, sizeof(c->req));
343 	bzero(&c->iri, sizeof(c->iri));
344 
345 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
346 	case -1:
347 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
348 		close_conn(fds, c);
349 		return;
350 
351 	case TLS_WANT_POLLIN:
352 		fds->events = POLLIN;
353 		return;
354 
355 	case TLS_WANT_POLLOUT:
356 		fds->events = POLLOUT;
357 		return;
358 	}
359 
360 	if (!trim_req_iri(c->req, &parse_err)
361 	    || !parse_iri(c->req, &c->iri, &parse_err)
362 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
363 		LOGI(c, "iri parse error: %s", parse_err);
364 		start_reply(fds, c, BAD_REQUEST, "invalid request");
365 		return;
366 	}
367 
368 	if (c->iri.port_no != conf.port
369 	    || strcmp(c->iri.schema, "gemini")
370 	    || strcmp(decoded, c->domain)) {
371 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
372 		return;
373 	}
374 
375 	open_file(fds, c);
376 }
377 
378 static void
379 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
380 {
381 	c->code = code;
382 	c->meta = meta;
383 	c->state = handle_start_reply;
384 	handle_start_reply(pfd, c);
385 }
386 
387 static void
388 handle_start_reply(struct pollfd *pfd, struct client *c)
389 {
390 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
391 	const char *lang;
392 	size_t len;
393 
394 	lang = vhost_lang(c->host, c->iri.path);
395 
396 	snprintf(buf, sizeof(buf), "%d ", c->code);
397 	strlcat(buf, c->meta, sizeof(buf));
398 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
399 		strlcat(buf, "; lang=", sizeof(buf));
400 		strlcat(buf, lang, sizeof(buf));
401 	}
402 
403 	len = strlcat(buf, "\r\n", sizeof(buf));
404 	assert(len < sizeof(buf));
405 
406 	switch (tls_write(c->ctx, buf, len)) {
407 	case -1:
408 		close_conn(pfd, c);
409 		return;
410 	case TLS_WANT_POLLIN:
411 		pfd->events = POLLIN;
412 		return;
413 	case TLS_WANT_POLLOUT:
414 		pfd->events = POLLOUT;
415 		return;
416 	}
417 
418 	log_request(c, buf, sizeof(buf));
419 
420 	/* we don't need a body */
421 	if (c->code != SUCCESS) {
422 		close_conn(pfd, c);
423 		return;
424 	}
425 
426 	/* advance the state machine */
427 	c->state = c->next;
428 	c->state(pfd, c);
429 }
430 
431 static void
432 start_cgi(const char *spath, const char *relpath,
433     struct pollfd *fds, struct client *c)
434 {
435 	char addr[NI_MAXHOST];
436 	const char *ruser, *cissuer, *chash;
437 	int e;
438 
439 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
440 	    addr, sizeof(addr),
441 	    NULL, 0,
442 	    NI_NUMERICHOST);
443 	if (e != 0)
444 		goto err;
445 
446 	if (tls_peer_cert_provided(c->ctx)) {
447 		ruser = tls_peer_cert_subject(c->ctx);
448 		cissuer = tls_peer_cert_issuer(c->ctx);
449 		chash = tls_peer_cert_hash(c->ctx);
450 	} else {
451 		ruser = NULL;
452 		cissuer = NULL;
453 		chash = NULL;
454 	}
455 
456 	if (!send_iri(exfd, &c->iri)
457 	    || !send_string(exfd, spath)
458 	    || !send_string(exfd, relpath)
459 	    || !send_string(exfd, addr)
460 	    || !send_string(exfd, ruser)
461 	    || !send_string(exfd, cissuer)
462 	    || !send_string(exfd, chash)
463 	    || !send_vhost(exfd, c->host))
464 		goto err;
465 
466 	close(c->fd);
467 	if ((c->fd = recv_fd(exfd)) == -1) {
468 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
469 		return;
470 	}
471 
472 	cgi_poll_on_child(fds, c);
473 	c->state = handle_cgi_reply;
474 	return;
475 
476 err:
477 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
478 	fatal("cannot talk to the executor process");
479 }
480 
481 static void
482 send_file(struct pollfd *fds, struct client *c)
483 {
484 	ssize_t ret, len;
485 
486 	len = (c->buf + c->len) - c->i;
487 
488 	while (len > 0) {
489 		switch (ret = tls_write(c->ctx, c->i, len)) {
490 		case -1:
491 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
492 			close_conn(fds, c);
493 			return;
494 
495 		case TLS_WANT_POLLIN:
496 			fds->events = POLLIN;
497 			return;
498 
499 		case TLS_WANT_POLLOUT:
500 			fds->events = POLLOUT;
501 			return;
502 
503 		default:
504 			c->i += ret;
505 			len -= ret;
506 			break;
507 		}
508 	}
509 
510 	close_conn(fds, c);
511 }
512 
513 static void
514 open_dir(struct pollfd *fds, struct client *c)
515 {
516 	size_t len;
517 	int dirfd;
518 	char *before_file;
519 
520 	len = strlen(c->iri.path);
521 	if (len > 0 && !ends_with(c->iri.path, "/")) {
522 		redirect_canonical_dir(fds, c);
523 		return;
524 	}
525 
526 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
527 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
528 	if (!ends_with(c->sbuf, "/"))
529 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
530 	before_file = strchr(c->sbuf, '\0');
531 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
532 	    sizeof(c->sbuf));
533 	if (len >= sizeof(c->sbuf)) {
534 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
535 		return;
536 	}
537 
538 	c->iri.path = c->sbuf;
539 
540 	/* close later unless we have to generate the dir listing */
541 	dirfd = c->fd;
542 	c->fd = -1;
543 
544 	switch (check_path(c, c->iri.path, &c->fd)) {
545 	case FILE_EXECUTABLE:
546 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
547 			start_cgi(c->iri.path, "", fds, c);
548 			break;
549 		}
550 
551 		/* fallthrough */
552 
553 	case FILE_EXISTS:
554                 load_file(fds, c);
555 		break;
556 
557 	case FILE_DIRECTORY:
558 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
559 		break;
560 
561 	case FILE_MISSING:
562 		*before_file = '\0';
563 
564 		if (!vhost_auto_index(c->host, c->iri.path)) {
565 			start_reply(fds, c, NOT_FOUND, "not found");
566 			break;
567 		}
568 
569 		c->fd = dirfd;
570 		c->next = enter_handle_dirlist;
571 
572 		if ((c->dir = fdopendir(c->fd)) == NULL) {
573 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
574 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
575 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
576 			return;
577 		}
578 		c->off = 0;
579 
580                 start_reply(fds, c, SUCCESS, "text/gemini");
581 		return;
582 
583 	default:
584 		/* unreachable */
585 		abort();
586 	}
587 
588 	close(dirfd);
589 }
590 
591 static void
592 redirect_canonical_dir(struct pollfd *fds, struct client *c)
593 {
594 	size_t len;
595 
596 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
597 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
598 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
599 
600 	if (len >= sizeof(c->sbuf)) {
601 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
602 		return;
603 	}
604 
605 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
606 }
607 
608 static void
609 enter_handle_dirlist(struct pollfd *fds, struct client *c)
610 {
611 	char b[PATH_MAX];
612 	size_t l;
613 
614 	strlcpy(b, c->iri.path, sizeof(b));
615 	l = snprintf(c->sbuf, sizeof(c->sbuf),
616 	    "# Index of %s\n\n", b);
617 	if (l >= sizeof(c->sbuf)) {
618 		/* this is impossible, given that we have enough space
619 		 * in c->sbuf to hold the ancilliary string plus the
620 		 * full path; but it wouldn't read nice without some
621 		 * error checking, and I'd like to avoid a strlen. */
622 		close_conn(fds, c);
623 		return;
624 	}
625 	c->len = l;
626 
627 	c->state = handle_dirlist;
628 	handle_dirlist(fds, c);
629 }
630 
631 static void
632 handle_dirlist(struct pollfd *fds, struct client *c)
633 {
634 	ssize_t r;
635 
636 	while (c->len > 0) {
637 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
638 		case -1:
639 			close_conn(fds, c);
640 			return;
641 		case TLS_WANT_POLLOUT:
642 			fds->events = POLLOUT;
643 			return;
644 		case TLS_WANT_POLLIN:
645 			fds->events = POLLIN;
646 			return;
647 		default:
648 			c->off += r;
649 			c->len -= r;
650 		}
651 	}
652 
653 	c->state = send_directory_listing;
654 	send_directory_listing(fds, c);
655 }
656 
657 static int
658 read_next_dir_entry(struct client *c)
659 {
660 	struct dirent *d;
661 
662 	do {
663 		errno = 0;
664 		if ((d = readdir(c->dir)) == NULL) {
665 			if (errno != 0)
666 				LOGE(c, "readdir: %s", strerror(errno));
667 			return 0;
668 		}
669 	} while (!strcmp(d->d_name, "."));
670 
671 	/* XXX: url escape */
672 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
673 	    d->d_name, d->d_name);
674 	c->len = strlen(c->sbuf);
675 	c->off = 0;
676 
677 	return 1;
678 }
679 
680 static void
681 send_directory_listing(struct pollfd *fds, struct client *c)
682 {
683 	ssize_t r;
684 
685 	while (1) {
686 		if (c->len == 0) {
687 			if (!read_next_dir_entry(c))
688 				goto end;
689 		}
690 
691 		while (c->len > 0) {
692 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
693 			case -1:
694 				goto end;
695 
696 			case TLS_WANT_POLLOUT:
697 				fds->events = POLLOUT;
698 				return;
699 
700 			case TLS_WANT_POLLIN:
701 				fds->events = POLLIN;
702 				return;
703 
704 			default:
705 				c->off += r;
706 				c->len -= r;
707 				break;
708 			}
709 		}
710 	}
711 
712 end:
713 	close_conn(fds, c);
714 }
715 
716 static inline void
717 cgi_poll_on_child(struct pollfd *fds, struct client *c)
718 {
719 	int fd;
720 
721 	if (c->waiting_on_child)
722 		return;
723 	c->waiting_on_child = 1;
724 
725 	fds->events = POLLIN;
726 
727 	fd = fds->fd;
728 	fds->fd = c->fd;
729 	c->fd = fd;
730 }
731 
732 static inline void
733 cgi_poll_on_client(struct pollfd *fds, struct client *c)
734 {
735 	int fd;
736 
737 	if (!c->waiting_on_child)
738 		return;
739 	c->waiting_on_child = 0;
740 
741 	fd = fds->fd;
742 	fds->fd = c->fd;
743 	c->fd = fd;
744 }
745 
746 /* accumulate the meta line from the cgi script. */
747 static void
748 handle_cgi_reply(struct pollfd *fds, struct client *c)
749 {
750 	void	*buf, *e;
751 	size_t	 len;
752 	ssize_t	 r;
753 
754 	buf = c->sbuf + c->len;
755 	len = sizeof(c->sbuf) - c->len;
756 
757 	/* we're polling on the child! */
758 	r = read(fds->fd, buf, len);
759 	if (r == 0 || r == -1) {
760 		cgi_poll_on_client(fds, c);
761 		start_reply(fds, c, CGI_ERROR, "CGI error");
762 		return;
763 	}
764 
765 	c->len += r;
766 
767 	/* TODO: error if the CGI script don't reply correctly */
768 	e = strchr(c->sbuf, '\n');
769 	if (e != NULL || c->len == sizeof(c->sbuf)) {
770 		log_request(c, c->sbuf, c->len);
771 
772 		c->off = 0;
773 		c->state = handle_cgi;
774 		c->state(fds, c);
775 		return;
776 	}
777 }
778 
779 static void
780 handle_cgi(struct pollfd *fds, struct client *c)
781 {
782 	ssize_t r;
783 
784 	/* ensure c->fd is the child and fds->fd the client */
785 	cgi_poll_on_client(fds, c);
786 
787 	while (1) {
788 		if (c->len == 0) {
789 			switch (r = read(c->fd, c->sbuf, sizeof(c->sbuf))) {
790 			case 0:
791 				goto end;
792 			case -1:
793 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
794 					cgi_poll_on_child(fds, c);
795 					return;
796 				}
797 				goto end;
798 			default:
799 				c->len = r;
800 				c->off = 0;
801 			}
802 		}
803 
804 		while (c->len > 0) {
805 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
806 			case -1:
807 				goto end;
808 
809 			case TLS_WANT_POLLOUT:
810 				fds->events = POLLOUT;
811 				return;
812 
813 			case TLS_WANT_POLLIN:
814 				fds->events = POLLIN;
815 				return;
816 
817 			default:
818                                 c->off += r;
819 				c->len -= r;
820 				break;
821 			}
822 		}
823 	}
824 
825 end:
826 	close_conn(fds, c);
827 }
828 
829 static void
830 close_conn(struct pollfd *pfd, struct client *c)
831 {
832 	c->state = close_conn;
833 
834 	switch (tls_close(c->ctx)) {
835 	case TLS_WANT_POLLIN:
836 		pfd->events = POLLIN;
837 		return;
838 	case TLS_WANT_POLLOUT:
839 		pfd->events = POLLOUT;
840 		return;
841 	}
842 
843 	connected_clients--;
844 
845 	tls_free(c->ctx);
846 	c->ctx = NULL;
847 
848 	if (c->buf != MAP_FAILED)
849 		munmap(c->buf, c->len);
850 
851 	if (c->fd != -1)
852 		close(c->fd);
853 
854 	if (c->dir != NULL)
855 		closedir(c->dir);
856 
857 	close(pfd->fd);
858 	pfd->fd = -1;
859 }
860 
861 static void
862 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
863 {
864 	int i, fd;
865 	struct sockaddr_storage addr;
866 	socklen_t len;
867 
868 	len = sizeof(addr);
869 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
870 		if (errno == EWOULDBLOCK)
871 			return;
872 		fatal("accept: %s", strerror(errno));
873 	}
874 
875 	mark_nonblock(fd);
876 
877 	for (i = 0; i < MAX_USERS; ++i) {
878 		if (fds[i].fd == -1) {
879 			bzero(&clients[i], sizeof(struct client));
880 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
881 				break; /* goodbye fd! */
882 
883 			fds[i].fd = fd;
884 			fds[i].events = POLLIN;
885 
886 			clients[i].state = handle_handshake;
887 			clients[i].next = send_file;
888 			clients[i].fd = -1;
889 			clients[i].waiting_on_child = 0;
890 			clients[i].buf = MAP_FAILED;
891 			clients[i].dir = NULL;
892 			clients[i].addr = addr;
893 
894 			connected_clients++;
895 			return;
896 		}
897 	}
898 
899 	close(fd);
900 }
901 
902 void
903 loop(struct tls *ctx, int sock4, int sock6)
904 {
905 	int i, n;
906 	struct client clients[MAX_USERS];
907 	struct pollfd fds[MAX_USERS];
908 
909 	for (i = 0; i < MAX_USERS; ++i) {
910 		fds[i].fd = -1;
911 		fds[i].events = POLLIN;
912 		bzero(&clients[i], sizeof(struct client));
913 	}
914 
915 	fds[0].fd = sock4;
916 	fds[1].fd = sock6;
917 
918 	for (;;) {
919 		if ((n = poll(fds, MAX_USERS, INFTIM)) == -1) {
920 			if (errno == EINTR) {
921 				fprintf(stderr, "connected clients: %d\n",
922 				    connected_clients);
923 			} else
924 				fatal("poll: %s", strerror(errno));
925 		}
926 
927 		for (i = 0; i < MAX_USERS && n > 0; i++) {
928 			if (fds[i].revents == 0)
929 				continue;
930 
931 			if (fds[i].revents & (POLLERR|POLLNVAL))
932 				fatal("bad fd %d: %s", fds[i].fd,
933 				    strerror(errno));
934 
935 			n--;
936 
937 			if (fds[i].revents & POLLHUP) {
938 				/* fds[i] may be the fd of the stdin
939 				 * of a cgi script that has exited. */
940 				if (!clients[i].waiting_on_child) {
941 					close_conn(&fds[i], &clients[i]);
942 					continue;
943 				}
944 			}
945 
946 			if (fds[i].fd == sock4)
947 				do_accept(sock4, ctx, fds, clients);
948 			else if (fds[i].fd == sock6)
949 				do_accept(sock6, ctx, fds, clients);
950 			else
951 				clients[i].state(&fds[i], &clients[i]);
952 		}
953 
954 		if (hupped) {
955 			if (connected_clients == 0)
956 				return;
957 
958 			fds[0].fd = -1;
959 			if (sock6 != -1)
960 				fds[1].fd = -1;
961 		}
962 	}
963 }