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 <event.h>
25 #include <fcntl.h>
26 #include <fnmatch.h>
27 #include <limits.h>
28 #include <string.h>
29 
30 #include "gmid.h"
31 
32 struct server {
33 	struct client	 clients[MAX_USERS];
34 	struct tls	*ctx;
35 };
36 
37 struct server_events {
38 	struct event	e4;
39 	int		has_ipv6;
40 	struct event	e6;
41 	struct event	sighup;
42 };
43 
44 int connected_clients;
45 
46 static inline void reschedule_read(int, struct client*, statefn);
47 static inline void reschedule_write(int, struct client*, statefn);
48 
49 static int	 check_path(struct client*, const char*, int*);
50 static void	 open_file(struct client*);
51 static void	 load_file(struct client*);
52 static void	 check_for_cgi(struct client*);
53 static void	 handle_handshake(int, short, void*);
54 static char	*strip_path(char*, int);
55 static void	 fmt_sbuf(const char*, struct client*, const char*);
56 static int	 apply_block_return(struct client*);
57 static void	 handle_open_conn(int, short, void*);
58 static void	 start_reply(struct client*, int, const char*);
59 static void	 handle_start_reply(int, short, void*);
60 static void	 start_cgi(const char*, const char*, struct client*);
61 static void	 send_file(int, short, void*);
62 static void	 open_dir(struct client*);
63 static void	 redirect_canonical_dir(struct client*);
64 static void	 enter_handle_dirlist(int, short, void*);
65 static void	 handle_dirlist(int, short, void*);
66 static int 	 read_next_dir_entry(struct client*);
67 static void	 send_directory_listing(int, short, void*);
68 static void	 handle_cgi_reply(int, short, void*);
69 static void	 handle_cgi(int, short, void*);
70 static void	 close_conn(int, short, void*);
71 static void	 do_accept(int, short, void*);
72 static void	 handle_sighup(int, short, void*);
73 
74 static inline void
75 reschedule_read(int fd, struct client *c, statefn fn)
76 {
77 	event_once(fd, EV_READ, fn, c, NULL);
78 }
79 
80 void
81 reschedule_write(int fd, struct client *c, statefn fn)
82 {
83 	event_once(fd, EV_WRITE, fn, c, NULL);
84 }
85 
86 const char *
87 vhost_lang(struct vhost *v, const char *path)
88 {
89 	struct location *loc;
90 
91 	if (v == NULL || path == NULL)
92 		return NULL;
93 
94 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
95 		if (loc->lang != NULL) {
96 			if (!fnmatch(loc->match, path, 0))
97 				return loc->lang;
98 		}
99 	}
100 
101 	return v->locations[0].lang;
102 }
103 
104 const char *
105 vhost_default_mime(struct vhost *v, const char *path)
106 {
107 	struct location *loc;
108 	const char *default_mime = "application/octet-stream";
109 
110 	if (v == NULL || path == NULL)
111 		return default_mime;
112 
113 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
114 		if (loc->default_mime != NULL) {
115 			if (!fnmatch(loc->match, path, 0))
116 				return loc->default_mime;
117 		}
118 	}
119 
120 	if (v->locations[0].default_mime != NULL)
121 		return v->locations[0].default_mime;
122 	return default_mime;
123 }
124 
125 const char *
126 vhost_index(struct vhost *v, const char *path)
127 {
128 	struct location *loc;
129 	const char *index = "index.gmi";
130 
131 	if (v == NULL || path == NULL)
132 		return index;
133 
134 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
135 		if (loc->index != NULL) {
136 			if (!fnmatch(loc->match, path, 0))
137 				return loc->index;
138 		}
139 	}
140 
141 	if (v->locations[0].index != NULL)
142 		return v->locations[0].index;
143 	return index;
144 }
145 
146 int
147 vhost_auto_index(struct vhost *v, const char *path)
148 {
149 	struct location *loc;
150 
151 	if (v == NULL || path == NULL)
152 		return 0;
153 
154 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
155 		if (loc->auto_index != 0) {
156 			if (!fnmatch(loc->match, path, 0))
157 				return loc->auto_index == 1;
158 		}
159 	}
160 
161 	return v->locations[0].auto_index == 1;
162 }
163 
164 int
165 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
166 {
167 	struct location *loc;
168 
169 	if (v == NULL || path == NULL)
170 		return 0;
171 
172 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
173 		if (loc->block_code != 0) {
174 			if (!fnmatch(loc->match, path, 0)) {
175 				*code = loc->block_code;
176 				*fmt = loc->block_fmt;
177 				return 1;
178 			}
179 		}
180 	}
181 
182 	*code = v->locations[0].block_code;
183 	*fmt = v->locations[0].block_fmt;
184 	return v->locations[0].block_code != 0;
185 }
186 
187 int
188 vhost_strip(struct vhost *v, const char *path)
189 {
190 	struct location *loc;
191 
192 	if (v == NULL || path == NULL)
193 		return 0;
194 
195 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
196 		if (loc->strip != 0) {
197 			if (!fnmatch(loc->match, path, 0))
198 				return loc->strip;
199 		}
200 	}
201 
202 	return v->locations[0].strip;
203 }
204 
205 static int
206 check_path(struct client *c, const char *path, int *fd)
207 {
208 	struct stat sb;
209 	const char *p;
210 	int flags;
211 
212 	assert(path != NULL);
213 
214 	if (*path == '\0')
215 		p = ".";
216 	else if (*path == '/')
217 		/* in send_dir we add an initial / (to be
218 		 * redirect-friendly), but here we want to skip it */
219 		p = path+1;
220 	else
221 		p = path;
222 
223 	flags = O_RDONLY | O_NOFOLLOW;
224 
225 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
226 		return FILE_MISSING;
227 
228 	if (fstat(*fd, &sb) == -1) {
229 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
230 		return FILE_MISSING;
231 	}
232 
233 	if (S_ISDIR(sb.st_mode))
234 		return FILE_DIRECTORY;
235 
236 	if (sb.st_mode & S_IXUSR)
237 		return FILE_EXECUTABLE;
238 
239 	return FILE_EXISTS;
240 }
241 
242 static void
243 open_file(struct client *c)
244 {
245 	switch (check_path(c, c->iri.path, &c->pfd)) {
246 	case FILE_EXECUTABLE:
247 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
248 			start_cgi(c->iri.path, "", c);
249 			return;
250 		}
251 
252 		/* fallthrough */
253 
254 	case FILE_EXISTS:
255 		load_file(c);
256 		return;
257 
258 	case FILE_DIRECTORY:
259 		open_dir(c);
260 		return;
261 
262 	case FILE_MISSING:
263 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
264 			check_for_cgi(c);
265 			return;
266 		}
267 		start_reply(c, NOT_FOUND, "not found");
268 		return;
269 
270 	default:
271 		/* unreachable */
272 		abort();
273 	}
274 }
275 
276 static void
277 load_file(struct client *c)
278 {
279 	if ((c->len = filesize(c->pfd)) == -1) {
280 		log_err(c, "failed to get file size for %s: %s",
281 		    c->iri.path, strerror(errno));
282 		start_reply(c, TEMP_FAILURE, "internal server error");
283 		return;
284 	}
285 
286 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
287 		    c->pfd, 0)) == MAP_FAILED) {
288 		log_err(c, "mmap: %s: %s", c->iri.path, strerror(errno));
289 		start_reply(c, TEMP_FAILURE, "internal server error");
290 		return;
291 	}
292 	c->i = c->buf;
293 	c->next = send_file;
294 	start_reply(c, SUCCESS, mime(c->host, c->iri.path));
295 }
296 
297 /*
298  * the inverse of this algorithm, i.e. starting from the start of the
299  * path + strlen(cgi), and checking if each component, should be
300  * faster.  But it's tedious to write.  This does the opposite: starts
301  * from the end and strip one component at a time, until either an
302  * executable is found or we emptied the path.
303  */
304 static void
305 check_for_cgi(struct client *c)
306 {
307 	char path[PATH_MAX];
308 	char *end;
309 
310 	strlcpy(path, c->iri.path, sizeof(path));
311 	end = strchr(path, '\0');
312 
313 	while (end > path) {
314 		/* go up one level.  UNIX paths are simple and POSIX
315 		 * dirname, with its ambiguities on if the given path
316 		 * is changed or not, gives me headaches. */
317 		while (*end != '/')
318 			end--;
319 		*end = '\0';
320 
321 		switch (check_path(c, path, &c->pfd)) {
322 		case FILE_EXECUTABLE:
323 			start_cgi(path, end+1, c);
324 			return;
325 		case FILE_MISSING:
326 			break;
327 		default:
328 			goto err;
329 		}
330 
331 		*end = '/';
332 		end--;
333 	}
334 
335 err:
336 	start_reply(c, NOT_FOUND, "not found");
337 	return;
338 }
339 
340 void
341 mark_nonblock(int fd)
342 {
343 	int flags;
344 
345 	if ((flags = fcntl(fd, F_GETFL)) == -1)
346 		fatal("fcntl(F_GETFL): %s", strerror(errno));
347 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
348 		fatal("fcntl(F_SETFL): %s", strerror(errno));
349 }
350 
351 static void
352 handle_handshake(int fd, short ev, void *d)
353 {
354 	struct client *c = d;
355 	struct vhost *h;
356 	const char *servname;
357 	const char *parse_err = "unknown error";
358 
359 	switch (tls_handshake(c->ctx)) {
360 	case 0:  /* success */
361 	case -1: /* already handshaked */
362 		break;
363 	case TLS_WANT_POLLIN:
364 		reschedule_read(fd, c, &handle_handshake);
365 		return;
366 	case TLS_WANT_POLLOUT:
367 		reschedule_write(fd, c, &handle_handshake);
368 		return;
369 	default:
370 		/* unreachable */
371 		abort();
372 	}
373 
374 	servname = tls_conn_servername(c->ctx);
375 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
376 		log_info(c, "puny_decode: %s", parse_err);
377 		goto err;
378 	}
379 
380 	for (h = hosts; h->domain != NULL; ++h) {
381 		if (!fnmatch(h->domain, c->domain, 0))
382 			break;
383 	}
384 
385 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
386 	    servname != NULL ? servname : "(null)",
387 	    c->domain,
388 	    h->domain != NULL ? h->domain : "(null)");
389 
390 	if (h->domain != NULL) {
391 		c->host = h;
392 		handle_open_conn(fd, ev, c);
393 		return;
394 	}
395 
396 err:
397 	if (servname != NULL)
398 		strncpy(c->req, servname, sizeof(c->req));
399 	else
400 		strncpy(c->req, "null", sizeof(c->req));
401 
402 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
403 }
404 
405 static char *
406 strip_path(char *path, int strip)
407 {
408 	char *t;
409 
410 	while (strip > 0) {
411 		if ((t = strchr(path, '/')) == NULL) {
412 			path = strchr(path, '\0');
413 			break;
414 		}
415 		path = t;
416 		strip--;
417 	}
418 
419 	return path;
420 }
421 
422 static void
423 fmt_sbuf(const char *fmt, struct client *c, const char *path)
424 {
425 	size_t i;
426         char buf[32];
427 
428 	memset(buf, 0, sizeof(buf));
429 	for (i = 0; *fmt; ++fmt) {
430 		if (i == sizeof(buf)-1 || *fmt == '%') {
431 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
432 			memset(buf, 0, sizeof(buf));
433 			i = 0;
434 		}
435 
436 		if (*fmt != '%') {
437 			buf[i++] = *fmt;
438 			continue;
439 		}
440 
441 		switch (*++fmt) {
442 		case '%':
443 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
444 			break;
445 		case 'p':
446 			strlcat(c->sbuf, path, sizeof(c->sbuf));
447 			break;
448 		case 'q':
449 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
450 			break;
451 		case 'P':
452 			snprintf(buf, sizeof(buf), "%d", conf.port);
453 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
454 			memset(buf, 0, sizeof(buf));
455 			break;
456 		case 'N':
457 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
458 			break;
459 		default:
460 			fatal("%s: unknown fmt specifier %c",
461 			    __func__, *fmt);
462 		}
463 	}
464 
465 	if (i != 0)
466 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
467 }
468 
469 /* 1 if a matching `block return' (and apply it), 0 otherwise */
470 static int
471 apply_block_return(struct client *c)
472 {
473 	const char *fmt, *path;
474 	int code;
475 
476 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
477 		return 0;
478 
479 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
480 	fmt_sbuf(fmt, c, path);
481 
482 	start_reply(c, code, c->sbuf);
483 	return 1;
484 }
485 
486 static void
487 handle_open_conn(int fd, short ev, void *d)
488 {
489 	struct client *c = d;
490 	const char *parse_err = "invalid request";
491 	char decoded[DOMAIN_NAME_LEN];
492 
493 	bzero(c->req, sizeof(c->req));
494 	bzero(&c->iri, sizeof(c->iri));
495 
496 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
497 	case -1:
498 		log_err(c, "tls_read: %s", tls_error(c->ctx));
499 		close_conn(fd, ev, c);
500 		return;
501 
502 	case TLS_WANT_POLLIN:
503 		reschedule_read(fd, c, &handle_open_conn);
504 		return;
505 
506 	case TLS_WANT_POLLOUT:
507 		reschedule_write(fd, c, &handle_open_conn);
508 		return;
509 	}
510 
511 	if (!trim_req_iri(c->req, &parse_err)
512 	    || !parse_iri(c->req, &c->iri, &parse_err)
513 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
514 		log_info(c, "iri parse error: %s", parse_err);
515 		start_reply(c, BAD_REQUEST, "invalid request");
516 		return;
517 	}
518 
519 	if (c->iri.port_no != conf.port
520 	    || strcmp(c->iri.schema, "gemini")
521 	    || strcmp(decoded, c->domain)) {
522 		start_reply(c, PROXY_REFUSED, "won't proxy request");
523 		return;
524 	}
525 
526 	if (apply_block_return(c))
527 		return;
528 
529 	if (c->host->entrypoint != NULL) {
530 		start_cgi(c->host->entrypoint, c->iri.path, c);
531 		return;
532 	}
533 
534 	open_file(c);
535 }
536 
537 static void
538 start_reply(struct client *c, int code, const char *meta)
539 {
540 	c->code = code;
541 	c->meta = meta;
542 	handle_start_reply(c->fd, 0, c);
543 }
544 
545 static void
546 handle_start_reply(int fd, short ev, void *d)
547 {
548 	struct client *c = d;
549 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
550 	const char *lang;
551 	size_t len;
552 
553 	lang = vhost_lang(c->host, c->iri.path);
554 
555 	snprintf(buf, sizeof(buf), "%d ", c->code);
556 	strlcat(buf, c->meta, sizeof(buf));
557 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
558 		strlcat(buf, "; lang=", sizeof(buf));
559 		strlcat(buf, lang, sizeof(buf));
560 	}
561 
562 	len = strlcat(buf, "\r\n", sizeof(buf));
563 	assert(len < sizeof(buf));
564 
565 	switch (tls_write(c->ctx, buf, len)) {
566 	case -1:
567 		close_conn(fd, ev, c);
568 		return;
569 	case TLS_WANT_POLLIN:
570 		reschedule_read(fd, c, &handle_start_reply);
571 		return;
572 	case TLS_WANT_POLLOUT:
573 		reschedule_write(fd, c, &handle_start_reply);
574 		return;
575 	}
576 
577 	log_request(c, buf, sizeof(buf));
578 
579 	if (c->code != SUCCESS)
580 		close_conn(fd, ev, c);
581 	else
582 		c->next(fd, ev, c);
583 }
584 
585 static void
586 start_cgi(const char *spath, const char *relpath, struct client *c)
587 {
588 	char addr[NI_MAXHOST];
589 	int e;
590 
591 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
592 	    addr, sizeof(addr),
593 	    NULL, 0,
594 	    NI_NUMERICHOST);
595 	if (e != 0)
596 		goto err;
597 
598 	if (!send_iri(exfd, &c->iri)
599 	    || !send_string(exfd, spath)
600 	    || !send_string(exfd, relpath)
601 	    || !send_string(exfd, addr)
602 	    || !send_string(exfd, tls_peer_cert_subject(c->ctx))
603 	    || !send_string(exfd, tls_peer_cert_issuer(c->ctx))
604 	    || !send_string(exfd, tls_peer_cert_hash(c->ctx))
605 	    || !send_time(exfd, tls_peer_cert_notbefore(c->ctx))
606 	    || !send_time(exfd, tls_peer_cert_notafter(c->ctx))
607 	    || !send_vhost(exfd, c->host))
608 		goto err;
609 
610 	close(c->pfd);
611 	if ((c->pfd = recv_fd(exfd)) == -1) {
612 		start_reply(c, TEMP_FAILURE, "internal server error");
613 		return;
614 	}
615 
616 	reschedule_read(c->pfd, c, &handle_cgi_reply);
617 	return;
618 
619 err:
620 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
621 	fatal("cannot talk to the executor process");
622 }
623 
624 static void
625 send_file(int fd, short ev, void *d)
626 {
627 	struct client *c = d;
628 	ssize_t ret, len;
629 
630 	len = (c->buf + c->len) - c->i;
631 
632 	while (len > 0) {
633 		switch (ret = tls_write(c->ctx, c->i, len)) {
634 		case -1:
635 			log_err(c, "tls_write: %s", tls_error(c->ctx));
636 			close_conn(fd, ev, c);
637 			return;
638 
639 		case TLS_WANT_POLLIN:
640 			reschedule_read(fd, c, &send_file);
641 			return;
642 
643 		case TLS_WANT_POLLOUT:
644 			reschedule_write(fd, c, &send_file);
645 			return;
646 
647 		default:
648 			c->i += ret;
649 			len -= ret;
650 			break;
651 		}
652 	}
653 
654 	close_conn(fd, ev, c);
655 }
656 
657 static void
658 open_dir(struct client *c)
659 {
660 	size_t len;
661 	int dirfd;
662 	char *before_file;
663 
664 	len = strlen(c->iri.path);
665 	if (len > 0 && !ends_with(c->iri.path, "/")) {
666 		redirect_canonical_dir(c);
667 		return;
668 	}
669 
670 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
671 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
672 	if (!ends_with(c->sbuf, "/"))
673 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
674 	before_file = strchr(c->sbuf, '\0');
675 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
676 	    sizeof(c->sbuf));
677 	if (len >= sizeof(c->sbuf)) {
678 		start_reply(c, TEMP_FAILURE, "internal server error");
679 		return;
680 	}
681 
682 	c->iri.path = c->sbuf;
683 
684 	/* close later unless we have to generate the dir listing */
685 	dirfd = c->pfd;
686 	c->pfd = -1;
687 
688 	switch (check_path(c, c->iri.path, &c->pfd)) {
689 	case FILE_EXECUTABLE:
690 		if (c->host->cgi != NULL && !fnmatch(c->host->cgi, c->iri.path, 0)) {
691 			start_cgi(c->iri.path, "", c);
692 			break;
693 		}
694 
695 		/* fallthrough */
696 
697 	case FILE_EXISTS:
698                 load_file(c);
699 		break;
700 
701 	case FILE_DIRECTORY:
702 		start_reply(c, TEMP_REDIRECT, c->sbuf);
703 		break;
704 
705 	case FILE_MISSING:
706 		*before_file = '\0';
707 
708 		if (!vhost_auto_index(c->host, c->iri.path)) {
709 			start_reply(c, NOT_FOUND, "not found");
710 			break;
711 		}
712 
713 		c->pfd = dirfd;
714 		c->next = enter_handle_dirlist;
715 
716 		if ((c->dir = fdopendir(c->pfd)) == NULL) {
717 			log_err(c, "fdopendir(%d) (vhost:%s) %s: %s",
718 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
719 			start_reply(c, TEMP_FAILURE, "internal server error");
720 			return;
721 		}
722 		c->off = 0;
723 
724                 start_reply(c, SUCCESS, "text/gemini");
725 		return;
726 
727 	default:
728 		/* unreachable */
729 		abort();
730 	}
731 
732 	close(dirfd);
733 }
734 
735 static void
736 redirect_canonical_dir(struct client *c)
737 {
738 	size_t len;
739 
740 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
741 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
742 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
743 
744 	if (len >= sizeof(c->sbuf)) {
745 		start_reply(c, TEMP_FAILURE, "internal server error");
746 		return;
747 	}
748 
749 	start_reply(c, TEMP_REDIRECT, c->sbuf);
750 }
751 
752 static void
753 enter_handle_dirlist(int fd, short ev, void *d)
754 {
755 	struct client *c = d;
756 	char b[PATH_MAX];
757 	size_t l;
758 
759 	strlcpy(b, c->iri.path, sizeof(b));
760 	l = snprintf(c->sbuf, sizeof(c->sbuf),
761 	    "# Index of %s\n\n", b);
762 	if (l >= sizeof(c->sbuf)) {
763 		/* this is impossible, given that we have enough space
764 		 * in c->sbuf to hold the ancilliary string plus the
765 		 * full path; but it wouldn't read nice without some
766 		 * error checking, and I'd like to avoid a strlen. */
767 		close_conn(fd, ev, c);
768 		return;
769 	}
770 
771 	c->len = l;
772 	handle_dirlist(fd, ev, c);
773 }
774 
775 static void
776 handle_dirlist(int fd, short ev, void *d)
777 {
778 	struct client *c = d;
779 	ssize_t r;
780 
781 	while (c->len > 0) {
782 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
783 		case -1:
784 			close_conn(fd, ev, c);
785 			return;
786 		case TLS_WANT_POLLOUT:
787 			reschedule_read(fd, c, &handle_dirlist);
788 			return;
789 		case TLS_WANT_POLLIN:
790 			reschedule_write(fd, c, &handle_dirlist);
791 			return;
792 		default:
793 			c->off += r;
794 			c->len -= r;
795 		}
796 	}
797 
798 	send_directory_listing(fd, ev, c);
799 }
800 
801 static int
802 read_next_dir_entry(struct client *c)
803 {
804 	struct dirent *d;
805 
806 	do {
807 		errno = 0;
808 		if ((d = readdir(c->dir)) == NULL) {
809 			if (errno != 0)
810 				log_err(c, "readdir: %s", strerror(errno));
811 			return 0;
812 		}
813 	} while (!strcmp(d->d_name, "."));
814 
815 	/* XXX: url escape */
816 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
817 	    d->d_name, d->d_name);
818 	c->len = strlen(c->sbuf);
819 	c->off = 0;
820 
821 	return 1;
822 }
823 
824 static void
825 send_directory_listing(int fd, short ev, void *d)
826 {
827 	struct client *c = d;
828 	ssize_t r;
829 
830 	while (1) {
831 		if (c->len == 0) {
832 			if (!read_next_dir_entry(c))
833 				goto end;
834 		}
835 
836 		while (c->len > 0) {
837 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
838 			case -1:
839 				goto end;
840 
841 			case TLS_WANT_POLLOUT:
842 				reschedule_read(fd, c, &send_directory_listing);
843 				return;
844 
845 			case TLS_WANT_POLLIN:
846 				reschedule_write(fd, c, &send_directory_listing);
847 				return;
848 
849 			default:
850 				c->off += r;
851 				c->len -= r;
852 				break;
853 			}
854 		}
855 	}
856 
857 end:
858 	close_conn(fd, ev, d);
859 }
860 
861 /* accumulate the meta line from the cgi script. */
862 static void
863 handle_cgi_reply(int fd, short ev, void *d)
864 {
865 	struct client *c = d;
866 	void	*buf, *e;
867 	size_t	 len;
868 	ssize_t	 r;
869 
870 
871 	buf = c->sbuf + c->len;
872 	len = sizeof(c->sbuf) - c->len;
873 
874 	r = read(c->pfd, buf, len);
875 	if (r == 0 || r == -1) {
876 		start_reply(c, CGI_ERROR, "CGI error");
877 		return;
878 	}
879 
880 	c->len += r;
881 
882 	/* TODO: error if the CGI script don't reply correctly */
883 	e = strchr(c->sbuf, '\n');
884 	if (e != NULL || c->len == sizeof(c->sbuf)) {
885 		log_request(c, c->sbuf, c->len);
886 
887 		c->off = 0;
888 		handle_cgi(fd, ev, c);
889 		return;
890 	}
891 
892 	reschedule_read(fd, c, &handle_cgi_reply);
893 }
894 
895 static void
896 handle_cgi(int fd, short ev, void *d)
897 {
898 	struct client *c = d;
899 	ssize_t r;
900 
901 	while (1) {
902 		if (c->len == 0) {
903 			switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
904 			case 0:
905 				goto end;
906 			case -1:
907 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
908 					reschedule_read(c->pfd, c, &handle_cgi);
909 					return;
910 				}
911 				goto end;
912 			default:
913 				c->len = r;
914 				c->off = 0;
915 			}
916 		}
917 
918 		while (c->len > 0) {
919 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
920 			case -1:
921 				goto end;
922 
923 			case TLS_WANT_POLLOUT:
924 				reschedule_read(c->fd, c, &handle_cgi);
925 				return;
926 
927 			case TLS_WANT_POLLIN:
928 				reschedule_write(c->fd, c, &handle_cgi);
929 				return;
930 
931 			default:
932                                 c->off += r;
933 				c->len -= r;
934 				break;
935 			}
936 		}
937 	}
938 
939 end:
940 	close_conn(c->fd, ev, d);
941 }
942 
943 static void
944 close_conn(int fd, short ev, void *d)
945 {
946 	struct client *c = d;
947 
948 	switch (tls_close(c->ctx)) {
949 	case TLS_WANT_POLLIN:
950 		reschedule_read(fd, c, &close_conn);
951 		return;
952 	case TLS_WANT_POLLOUT:
953 		reschedule_read(fd, c, &close_conn);
954 		return;
955 	}
956 
957 	connected_clients--;
958 
959 	tls_free(c->ctx);
960 	c->ctx = NULL;
961 
962 	if (c->buf != MAP_FAILED)
963 		munmap(c->buf, c->len);
964 
965 	if (c->pfd != -1)
966 		close(c->pfd);
967 
968 	if (c->dir != NULL)
969 		closedir(c->dir);
970 
971 	close(c->fd);
972 	c->fd = -1;
973 }
974 
975 static void
976 do_accept(int sock, short et, void *d)
977 {
978 	struct client *c;
979 	struct server *s = d;
980 	struct sockaddr_storage addr;
981 	struct sockaddr *saddr;
982 	socklen_t len;
983 	int i, fd;
984 
985 	(void)et;
986 
987 
988 	saddr = (struct sockaddr*)&addr;
989 	len = sizeof(addr);
990 	if ((fd = accept4(sock, saddr, &len, SOCK_NONBLOCK)) == -1) {
991 		if (errno == EWOULDBLOCK || errno == EAGAIN)
992 			return;
993 		fatal("accept: %s", strerror(errno));
994 	}
995 
996 	for (i = 0; i < MAX_USERS; ++i) {
997 		c = &s->clients[i];
998 		if (c->fd == -1) {
999 			memset(c, 0, sizeof(*c));
1000 			if (tls_accept_socket(s->ctx, &c->ctx, fd) == -1)
1001 				break; /* goodbye fd! */
1002 
1003 			c->fd = fd;
1004 			c->pfd = -1;
1005 			c->buf = MAP_FAILED;
1006 			c->dir = NULL;
1007 			c->addr = addr;
1008 
1009 			reschedule_read(fd, c, &handle_handshake);
1010 			connected_clients++;
1011 			return;
1012 		}
1013 	}
1014 
1015 	close(fd);
1016 }
1017 
1018 static void
1019 handle_sighup(int fd, short ev, void *d)
1020 {
1021 	struct server_events *events = d;
1022 
1023 	(void)fd;
1024 	(void)ev;
1025 
1026 	event_del(&events->e4);
1027 	if (events->has_ipv6)
1028 		event_del(&events->e6);
1029 	signal_del(&events->sighup);
1030 }
1031 
1032 static void
1033 handle_siginfo(int fd, short ev, void *d)
1034 {
1035 	(void)fd;
1036 	(void)ev;
1037 	(void)d;
1038 
1039 	log_info(NULL, "%d connected clients", connected_clients);
1040 }
1041 
1042 void
1043 loop(struct tls *ctx, int sock4, int sock6)
1044 {
1045 	struct server_events events;
1046 	struct server server;
1047 	struct event info;
1048 	size_t i;
1049 
1050 	event_init();
1051 
1052 	memset(&events, 0, sizeof(events));
1053 	memset(&server, 0, sizeof(server));
1054 	for (i = 0; i < MAX_USERS; ++i)
1055 		server.clients[i].fd = -1;
1056 
1057 	event_set(&events.e4, sock4, EV_READ | EV_PERSIST, &do_accept, &server);
1058 	event_add(&events.e4, NULL);
1059 
1060 	if (sock6 != -1) {
1061 		events.has_ipv6 = 1;
1062 		event_set(&events.e6, sock6, EV_READ | EV_PERSIST, &do_accept, &server);
1063 		event_add(&events.e6, NULL);
1064 	}
1065 
1066 	signal_set(&events.sighup, SIGHUP, &handle_sighup, &events);
1067 	signal_add(&events.sighup, NULL);
1068 
1069 #ifdef SIGINFO
1070 	signal_set(&info, SIGINFO, &handle_siginfo, NULL);
1071 	signal_add(&info, NULL);
1072 #endif
1073 	signal_set(&info, SIGUSR2, &handle_siginfo, NULL);
1074 	signal_add(&info, NULL);
1075 
1076 	server.ctx = ctx;
1077 
1078 	sandbox();
1079 	event_dispatch();
1080 	_exit(0);
1081 }