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 "gmid.h"
18 
19 #include <sys/stat.h>
20 
21 #include <netdb.h>
22 
23 #include <assert.h>
24 #include <errno.h>
25 #include <event.h>
26 #include <fcntl.h>
27 #include <fnmatch.h>
28 #include <limits.h>
29 #include <string.h>
30 
31 struct server {
32 	struct client	 clients[MAX_USERS];
33 	struct tls	*ctx;
34 };
35 
36 static struct event e4, e6, sighup, siginfo, sigusr2;
37 static int has_ipv6, has_siginfo;
38 
39 int connected_clients;
40 
41 static inline int matches(const char*, const char*);
42 
43 static inline void reschedule_read(int, struct client*, statefn);
44 static inline void reschedule_write(int, struct client*, statefn);
45 
46 static int	 check_path(struct client*, const char*, int*);
47 static void	 open_file(struct client*);
48 static void	 check_for_cgi(struct client*);
49 static void	 handle_handshake(int, short, void*);
50 static char	*strip_path(char*, int);
51 static void	 fmt_sbuf(const char*, struct client*, const char*);
52 static int	 apply_block_return(struct client*);
53 static int	 apply_require_ca(struct client*);
54 static void	 handle_open_conn(int, short, void*);
55 static void	 start_reply(struct client*, int, const char*);
56 static void	 handle_start_reply(int, short, void*);
57 static void	 start_cgi(const char*, const char*, struct client*);
58 static void	 open_dir(struct client*);
59 static void	 redirect_canonical_dir(struct client*);
60 static void	 enter_handle_dirlist(int, short, void*);
61 static void	 handle_dirlist(int, short, void*);
62 static int 	 read_next_dir_entry(struct client*);
63 static void	 send_directory_listing(int, short, void*);
64 static void	 handle_cgi_reply(int, short, void*);
65 static void	 handle_copy(int, short, void*);
66 static void	 close_conn(int, short, void*);
67 static void	 do_accept(int, short, void*);
68 static void	 handle_sighup(int, short, void*);
69 
70 static inline int
71 matches(const char *pattern, const char *path)
72 {
73 	if (*path == '/')
74 		path++;
75 	return !fnmatch(pattern, path, 0);
76 }
77 
78 static inline void
79 reschedule_read(int fd, struct client *c, statefn fn)
80 {
81 	event_once(fd, EV_READ, fn, c, NULL);
82 }
83 
84 static inline void
85 reschedule_write(int fd, struct client *c, statefn fn)
86 {
87 	event_once(fd, EV_WRITE, fn, c, NULL);
88 }
89 
90 const char *
91 vhost_lang(struct vhost *v, const char *path)
92 {
93 	struct location *loc;
94 
95 	if (v == NULL || path == NULL)
96 		return NULL;
97 
98 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
99 		if (loc->lang != NULL) {
100 			if (matches(loc->match, path))
101 				return loc->lang;
102 		}
103 	}
104 
105 	return v->locations[0].lang;
106 }
107 
108 const char *
109 vhost_default_mime(struct vhost *v, const char *path)
110 {
111 	struct location *loc;
112 	const char *default_mime = "application/octet-stream";
113 
114 	if (v == NULL || path == NULL)
115 		return default_mime;
116 
117 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
118 		if (loc->default_mime != NULL) {
119 			if (matches(loc->match, path))
120 				return loc->default_mime;
121 		}
122 	}
123 
124 	if (v->locations[0].default_mime != NULL)
125 		return v->locations[0].default_mime;
126 	return default_mime;
127 }
128 
129 const char *
130 vhost_index(struct vhost *v, const char *path)
131 {
132 	struct location *loc;
133 	const char *index = "index.gmi";
134 
135 	if (v == NULL || path == NULL)
136 		return index;
137 
138 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
139 		if (loc->index != NULL) {
140 			if (matches(loc->match, path))
141 				return loc->index;
142 		}
143 	}
144 
145 	if (v->locations[0].index != NULL)
146 		return v->locations[0].index;
147 	return index;
148 }
149 
150 int
151 vhost_auto_index(struct vhost *v, const char *path)
152 {
153 	struct location *loc;
154 
155 	if (v == NULL || path == NULL)
156 		return 0;
157 
158 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
159 		if (loc->auto_index != 0) {
160 			if (matches(loc->match, path))
161 				return loc->auto_index == 1;
162 		}
163 	}
164 
165 	return v->locations[0].auto_index == 1;
166 }
167 
168 int
169 vhost_block_return(struct vhost *v, const char *path, int *code, const char **fmt)
170 {
171 	struct location *loc;
172 
173 	if (v == NULL || path == NULL)
174 		return 0;
175 
176 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
177 		if (loc->block_code != 0) {
178 			if (matches(loc->match, path)) {
179 				*code = loc->block_code;
180 				*fmt = loc->block_fmt;
181 				return 1;
182 			}
183 		}
184 	}
185 
186 	*code = v->locations[0].block_code;
187 	*fmt = v->locations[0].block_fmt;
188 	return v->locations[0].block_code != 0;
189 }
190 
191 int
192 vhost_strip(struct vhost *v, const char *path)
193 {
194 	struct location *loc;
195 
196 	if (v == NULL || path == NULL)
197 		return 0;
198 
199 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
200 		if (loc->strip != 0) {
201 			if (matches(loc->match, path))
202 				return loc->strip;
203 		}
204 	}
205 
206 	return v->locations[0].strip;
207 }
208 
209 X509_STORE *
210 vhost_require_ca(struct vhost *v, const char *path)
211 {
212 	struct location *loc;
213 
214 	if (v == NULL || path == NULL)
215 		return NULL;
216 
217 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
218 		if (loc->reqca != NULL) {
219 			if (matches(loc->match, path))
220 				return loc->reqca;
221 		}
222 	}
223 
224 	return v->locations[0].reqca;
225 }
226 
227 int
228 vhost_disable_log(struct vhost *v, const char *path)
229 {
230 	struct location *loc;
231 
232 	if (v == NULL || path == NULL)
233 		return 0;
234 
235 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
236 		if (loc->disable_log && matches(loc->match, path))
237 				return 1;
238 	}
239 
240 	return v->locations[0].disable_log;
241 }
242 
243 static int
244 check_path(struct client *c, const char *path, int *fd)
245 {
246 	struct stat sb;
247 	const char *p;
248 	int flags;
249 
250 	assert(path != NULL);
251 
252 	if (*path == '\0')
253 		p = ".";
254 	else if (*path == '/')
255 		/* in send_dir we add an initial / (to be
256 		 * redirect-friendly), but here we want to skip it */
257 		p = path+1;
258 	else
259 		p = path;
260 
261 	flags = O_RDONLY | O_NOFOLLOW;
262 
263 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
264 		return FILE_MISSING;
265 
266 	if (fstat(*fd, &sb) == -1) {
267 		log_notice(c, "failed stat for %s: %s", path, strerror(errno));
268 		return FILE_MISSING;
269 	}
270 
271 	if (S_ISDIR(sb.st_mode))
272 		return FILE_DIRECTORY;
273 
274 	if (sb.st_mode & S_IXUSR)
275 		return FILE_EXECUTABLE;
276 
277 	return FILE_EXISTS;
278 }
279 
280 static void
281 open_file(struct client *c)
282 {
283 	switch (check_path(c, c->iri.path, &c->pfd)) {
284 	case FILE_EXECUTABLE:
285 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
286 			start_cgi(c->iri.path, "", c);
287 			return;
288 		}
289 
290 		/* fallthrough */
291 
292 	case FILE_EXISTS:
293 		c->next = handle_copy;
294 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
295 		return;
296 
297 	case FILE_DIRECTORY:
298 		open_dir(c);
299 		return;
300 
301 	case FILE_MISSING:
302 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
303 			check_for_cgi(c);
304 			return;
305 		}
306 		start_reply(c, NOT_FOUND, "not found");
307 		return;
308 
309 	default:
310 		/* unreachable */
311 		abort();
312 	}
313 }
314 
315 /*
316  * the inverse of this algorithm, i.e. starting from the start of the
317  * path + strlen(cgi), and checking if each component, should be
318  * faster.  But it's tedious to write.  This does the opposite: starts
319  * from the end and strip one component at a time, until either an
320  * executable is found or we emptied the path.
321  */
322 static void
323 check_for_cgi(struct client *c)
324 {
325 	char path[PATH_MAX];
326 	char *end;
327 
328 	strlcpy(path, c->iri.path, sizeof(path));
329 	end = strchr(path, '\0');
330 
331 	while (end > path) {
332 		/* go up one level.  UNIX paths are simple and POSIX
333 		 * dirname, with its ambiguities on if the given path
334 		 * is changed or not, gives me headaches. */
335 		while (*end != '/')
336 			end--;
337 		*end = '\0';
338 
339 		switch (check_path(c, path, &c->pfd)) {
340 		case FILE_EXECUTABLE:
341 			start_cgi(path, end+1, c);
342 			return;
343 		case FILE_MISSING:
344 			break;
345 		default:
346 			goto err;
347 		}
348 
349 		*end = '/';
350 		end--;
351 	}
352 
353 err:
354 	start_reply(c, NOT_FOUND, "not found");
355 	return;
356 }
357 
358 void
359 mark_nonblock(int fd)
360 {
361 	int flags;
362 
363 	if ((flags = fcntl(fd, F_GETFL)) == -1)
364 		fatal("fcntl(F_GETFL): %s", strerror(errno));
365 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
366 		fatal("fcntl(F_SETFL): %s", strerror(errno));
367 }
368 
369 static void
370 handle_handshake(int fd, short ev, void *d)
371 {
372 	struct client *c = d;
373 	struct vhost *h;
374 	const char *servname;
375 	const char *parse_err = "unknown error";
376 
377 	switch (tls_handshake(c->ctx)) {
378 	case 0:  /* success */
379 	case -1: /* already handshaked */
380 		break;
381 	case TLS_WANT_POLLIN:
382 		reschedule_read(fd, c, &handle_handshake);
383 		return;
384 	case TLS_WANT_POLLOUT:
385 		reschedule_write(fd, c, &handle_handshake);
386 		return;
387 	default:
388 		/* unreachable */
389 		abort();
390 	}
391 
392 	servname = tls_conn_servername(c->ctx);
393 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
394 		log_info(c, "puny_decode: %s", parse_err);
395 		goto err;
396 	}
397 
398 	for (h = hosts; h->domain != NULL; ++h) {
399 		if (matches(h->domain, c->domain))
400 			break;
401 	}
402 
403 	log_debug(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"",
404 	    servname != NULL ? servname : "(null)",
405 	    c->domain,
406 	    h->domain != NULL ? h->domain : "(null)");
407 
408 	if (h->domain != NULL) {
409 		c->host = h;
410 		handle_open_conn(fd, ev, c);
411 		return;
412 	}
413 
414 err:
415 	if (servname != NULL)
416 		strncpy(c->req, servname, sizeof(c->req));
417 	else
418 		strncpy(c->req, "null", sizeof(c->req));
419 
420 	start_reply(c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
421 }
422 
423 static char *
424 strip_path(char *path, int strip)
425 {
426 	char *t;
427 
428 	while (strip > 0) {
429 		if ((t = strchr(path, '/')) == NULL) {
430 			path = strchr(path, '\0');
431 			break;
432 		}
433 		path = t;
434 		strip--;
435 	}
436 
437 	return path;
438 }
439 
440 static void
441 fmt_sbuf(const char *fmt, struct client *c, const char *path)
442 {
443 	size_t i;
444         char buf[32];
445 
446 	memset(buf, 0, sizeof(buf));
447 	for (i = 0; *fmt; ++fmt) {
448 		if (i == sizeof(buf)-1 || *fmt == '%') {
449 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
450 			memset(buf, 0, sizeof(buf));
451 			i = 0;
452 		}
453 
454 		if (*fmt != '%') {
455 			buf[i++] = *fmt;
456 			continue;
457 		}
458 
459 		switch (*++fmt) {
460 		case '%':
461 			strlcat(c->sbuf, "%", sizeof(c->sbuf));
462 			break;
463 		case 'p':
464 			strlcat(c->sbuf, path, sizeof(c->sbuf));
465 			break;
466 		case 'q':
467 			strlcat(c->sbuf, c->iri.query, sizeof(c->sbuf));
468 			break;
469 		case 'P':
470 			snprintf(buf, sizeof(buf), "%d", conf.port);
471 			strlcat(c->sbuf, buf, sizeof(c->sbuf));
472 			memset(buf, 0, sizeof(buf));
473 			break;
474 		case 'N':
475 			strlcat(c->sbuf, c->domain, sizeof(c->sbuf));
476 			break;
477 		default:
478 			fatal("%s: unknown fmt specifier %c",
479 			    __func__, *fmt);
480 		}
481 	}
482 
483 	if (i != 0)
484 		strlcat(c->sbuf, buf, sizeof(c->sbuf));
485 }
486 
487 /* 1 if a matching `block return' (and apply it), 0 otherwise */
488 static int
489 apply_block_return(struct client *c)
490 {
491 	const char *fmt, *path;
492 	int code;
493 
494 	if (!vhost_block_return(c->host, c->iri.path, &code, &fmt))
495 		return 0;
496 
497 	path = strip_path(c->iri.path, vhost_strip(c->host, c->iri.path));
498 	fmt_sbuf(fmt, c, path);
499 
500 	start_reply(c, code, c->sbuf);
501 	return 1;
502 }
503 
504 /* 1 if matching `require client ca' fails (and apply it), 0 otherwise */
505 static int
506 apply_require_ca(struct client *c)
507 {
508 	X509_STORE	*store;
509 	const uint8_t	*cert;
510 	size_t		 len;
511 
512 	if ((store = vhost_require_ca(c->host, c->iri.path)) == NULL)
513 		return 0;
514 
515 	if (!tls_peer_cert_provided(c->ctx)) {
516 		start_reply(c, CLIENT_CERT_REQ, "client certificate required");
517 		return 1;
518 	}
519 
520 	cert = tls_peer_cert_chain_pem(c->ctx, &len);
521 	if (!validate_against_ca(store, cert, len)) {
522 		start_reply(c, CERT_NOT_AUTH, "certificate not authorised");
523 		return 1;
524 	}
525 
526 	return 0;
527 }
528 
529 static void
530 handle_open_conn(int fd, short ev, void *d)
531 {
532 	struct client *c = d;
533 	const char *parse_err = "invalid request";
534 	char decoded[DOMAIN_NAME_LEN];
535 
536 	bzero(c->req, sizeof(c->req));
537 	bzero(&c->iri, sizeof(c->iri));
538 
539 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
540 	case -1:
541 		log_err(c, "tls_read: %s", tls_error(c->ctx));
542 		close_conn(fd, ev, c);
543 		return;
544 
545 	case TLS_WANT_POLLIN:
546 		reschedule_read(fd, c, &handle_open_conn);
547 		return;
548 
549 	case TLS_WANT_POLLOUT:
550 		reschedule_write(fd, c, &handle_open_conn);
551 		return;
552 	}
553 
554 	if (!trim_req_iri(c->req, &parse_err)
555 	    || !parse_iri(c->req, &c->iri, &parse_err)
556 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
557 		log_info(c, "iri parse error: %s", parse_err);
558 		start_reply(c, BAD_REQUEST, "invalid request");
559 		return;
560 	}
561 
562 	if (c->iri.port_no != conf.port
563 	    || strcmp(c->iri.schema, "gemini")
564 	    || strcmp(decoded, c->domain)) {
565 		start_reply(c, PROXY_REFUSED, "won't proxy request");
566 		return;
567 	}
568 
569 	if (apply_require_ca(c))
570 		return;
571 
572 	if (apply_block_return(c))
573 		return;
574 
575 	if (c->host->entrypoint != NULL) {
576 		start_cgi(c->host->entrypoint, c->iri.path, c);
577 		return;
578 	}
579 
580 	open_file(c);
581 }
582 
583 static void
584 start_reply(struct client *c, int code, const char *meta)
585 {
586 	c->code = code;
587 	c->meta = meta;
588 	handle_start_reply(c->fd, 0, c);
589 }
590 
591 static void
592 handle_start_reply(int fd, short ev, void *d)
593 {
594 	struct client *c = d;
595 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
596 	const char *lang;
597 	size_t len;
598 
599 	lang = vhost_lang(c->host, c->iri.path);
600 
601 	snprintf(buf, sizeof(buf), "%d ", c->code);
602 	strlcat(buf, c->meta, sizeof(buf));
603 	if (!strcmp(c->meta, "text/gemini") && lang != NULL) {
604 		strlcat(buf, "; lang=", sizeof(buf));
605 		strlcat(buf, lang, sizeof(buf));
606 	}
607 
608 	len = strlcat(buf, "\r\n", sizeof(buf));
609 	assert(len < sizeof(buf));
610 
611 	switch (tls_write(c->ctx, buf, len)) {
612 	case -1:
613 		close_conn(fd, ev, c);
614 		return;
615 	case TLS_WANT_POLLIN:
616 		reschedule_read(fd, c, &handle_start_reply);
617 		return;
618 	case TLS_WANT_POLLOUT:
619 		reschedule_write(fd, c, &handle_start_reply);
620 		return;
621 	}
622 
623 	if (!vhost_disable_log(c->host, c->iri.path))
624 		log_request(c, buf, sizeof(buf));
625 
626 	if (c->code != SUCCESS)
627 		close_conn(fd, ev, c);
628 	else
629 		c->next(fd, ev, c);
630 }
631 
632 static void
633 start_cgi(const char *spath, const char *relpath, struct client *c)
634 {
635 	char addr[NI_MAXHOST];
636 	int e;
637 
638 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
639 	    addr, sizeof(addr),
640 	    NULL, 0,
641 	    NI_NUMERICHOST);
642 	if (e != 0)
643 		goto err;
644 
645 	if (!send_iri(exfd, &c->iri)
646 	    || !send_string(exfd, spath)
647 	    || !send_string(exfd, relpath)
648 	    || !send_string(exfd, addr)
649 	    || !send_string(exfd, tls_peer_cert_subject(c->ctx))
650 	    || !send_string(exfd, tls_peer_cert_issuer(c->ctx))
651 	    || !send_string(exfd, tls_peer_cert_hash(c->ctx))
652 	    || !send_time(exfd, tls_peer_cert_notbefore(c->ctx))
653 	    || !send_time(exfd, tls_peer_cert_notafter(c->ctx))
654 	    || !send_vhost(exfd, c->host))
655 		goto err;
656 
657 	close(c->pfd);
658 	if ((c->pfd = recv_fd(exfd)) == -1) {
659 		start_reply(c, TEMP_FAILURE, "internal server error");
660 		return;
661 	}
662 
663 	reschedule_read(c->pfd, c, &handle_cgi_reply);
664 	return;
665 
666 err:
667 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
668 	fatal("cannot talk to the executor process");
669 }
670 
671 static void
672 open_dir(struct client *c)
673 {
674 	size_t len;
675 	int dirfd;
676 	char *before_file;
677 
678 	len = strlen(c->iri.path);
679 	if (len > 0 && !ends_with(c->iri.path, "/")) {
680 		redirect_canonical_dir(c);
681 		return;
682 	}
683 
684 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
685 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
686 	if (!ends_with(c->sbuf, "/"))
687 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
688 	before_file = strchr(c->sbuf, '\0');
689 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
690 	    sizeof(c->sbuf));
691 	if (len >= sizeof(c->sbuf)) {
692 		start_reply(c, TEMP_FAILURE, "internal server error");
693 		return;
694 	}
695 
696 	c->iri.path = c->sbuf;
697 
698 	/* close later unless we have to generate the dir listing */
699 	dirfd = c->pfd;
700 	c->pfd = -1;
701 
702 	switch (check_path(c, c->iri.path, &c->pfd)) {
703 	case FILE_EXECUTABLE:
704 		if (c->host->cgi != NULL && matches(c->host->cgi, c->iri.path)) {
705 			start_cgi(c->iri.path, "", c);
706 			break;
707 		}
708 
709 		/* fallthrough */
710 
711 	case FILE_EXISTS:
712 		c->next = handle_copy;
713 		start_reply(c, SUCCESS, mime(c->host, c->iri.path));
714 		break;
715 
716 	case FILE_DIRECTORY:
717 		start_reply(c, TEMP_REDIRECT, c->sbuf);
718 		break;
719 
720 	case FILE_MISSING:
721 		*before_file = '\0';
722 
723 		if (!vhost_auto_index(c->host, c->iri.path)) {
724 			start_reply(c, NOT_FOUND, "not found");
725 			break;
726 		}
727 
728 		c->pfd = dirfd;
729 		c->next = enter_handle_dirlist;
730 
731 		if ((c->dir = fdopendir(c->pfd)) == NULL) {
732 			log_err(c, "fdopendir(%d) (vhost:%s) %s: %s",
733 			    c->pfd, c->host->domain, c->iri.path, strerror(errno));
734 			start_reply(c, TEMP_FAILURE, "internal server error");
735 			return;
736 		}
737 		c->off = 0;
738 
739                 start_reply(c, SUCCESS, "text/gemini");
740 		return;
741 
742 	default:
743 		/* unreachable */
744 		abort();
745 	}
746 
747 	close(dirfd);
748 }
749 
750 static void
751 redirect_canonical_dir(struct client *c)
752 {
753 	size_t len;
754 
755 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
756 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
757 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
758 
759 	if (len >= sizeof(c->sbuf)) {
760 		start_reply(c, TEMP_FAILURE, "internal server error");
761 		return;
762 	}
763 
764 	start_reply(c, TEMP_REDIRECT, c->sbuf);
765 }
766 
767 static void
768 enter_handle_dirlist(int fd, short ev, void *d)
769 {
770 	struct client *c = d;
771 	char b[PATH_MAX];
772 	size_t l;
773 
774 	strlcpy(b, c->iri.path, sizeof(b));
775 	l = snprintf(c->sbuf, sizeof(c->sbuf),
776 	    "# Index of %s\n\n", b);
777 	if (l >= sizeof(c->sbuf)) {
778 		/* this is impossible, given that we have enough space
779 		 * in c->sbuf to hold the ancilliary string plus the
780 		 * full path; but it wouldn't read nice without some
781 		 * error checking, and I'd like to avoid a strlen. */
782 		close_conn(fd, ev, c);
783 		return;
784 	}
785 
786 	c->len = l;
787 	handle_dirlist(fd, ev, c);
788 }
789 
790 static void
791 handle_dirlist(int fd, short ev, void *d)
792 {
793 	struct client *c = d;
794 	ssize_t r;
795 
796 	while (c->len > 0) {
797 		switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
798 		case -1:
799 			close_conn(fd, ev, c);
800 			return;
801 		case TLS_WANT_POLLOUT:
802 			reschedule_read(fd, c, &handle_dirlist);
803 			return;
804 		case TLS_WANT_POLLIN:
805 			reschedule_write(fd, c, &handle_dirlist);
806 			return;
807 		default:
808 			c->off += r;
809 			c->len -= r;
810 		}
811 	}
812 
813 	send_directory_listing(fd, ev, c);
814 }
815 
816 static int
817 read_next_dir_entry(struct client *c)
818 {
819 	struct dirent *d;
820 
821 	do {
822 		errno = 0;
823 		if ((d = readdir(c->dir)) == NULL) {
824 			if (errno != 0)
825 				log_err(c, "readdir: %s", strerror(errno));
826 			return 0;
827 		}
828 	} while (!strcmp(d->d_name, "."));
829 
830 	/* XXX: url escape */
831 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
832 	    d->d_name, d->d_name);
833 	c->len = strlen(c->sbuf);
834 	c->off = 0;
835 
836 	return 1;
837 }
838 
839 static void
840 send_directory_listing(int fd, short ev, void *d)
841 {
842 	struct client *c = d;
843 	ssize_t r;
844 
845 	while (1) {
846 		if (c->len == 0) {
847 			if (!read_next_dir_entry(c))
848 				goto end;
849 		}
850 
851 		while (c->len > 0) {
852 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
853 			case -1:
854 				goto end;
855 
856 			case TLS_WANT_POLLOUT:
857 				reschedule_read(fd, c, &send_directory_listing);
858 				return;
859 
860 			case TLS_WANT_POLLIN:
861 				reschedule_write(fd, c, &send_directory_listing);
862 				return;
863 
864 			default:
865 				c->off += r;
866 				c->len -= r;
867 				break;
868 			}
869 		}
870 	}
871 
872 end:
873 	close_conn(fd, ev, d);
874 }
875 
876 /* accumulate the meta line from the cgi script. */
877 static void
878 handle_cgi_reply(int fd, short ev, void *d)
879 {
880 	struct client *c = d;
881 	void	*buf, *e;
882 	size_t	 len;
883 	ssize_t	 r;
884 
885 
886 	buf = c->sbuf + c->len;
887 	len = sizeof(c->sbuf) - c->len;
888 
889 	r = read(c->pfd, buf, len);
890 	if (r == 0 || r == -1) {
891 		start_reply(c, CGI_ERROR, "CGI error");
892 		return;
893 	}
894 
895 	c->len += r;
896 
897 	/* TODO: error if the CGI script don't reply correctly */
898 	e = strchr(c->sbuf, '\n');
899 	if (e != NULL || c->len == sizeof(c->sbuf)) {
900 		log_request(c, c->sbuf, c->len);
901 
902 		c->off = 0;
903 		handle_copy(fd, ev, c);
904 		return;
905 	}
906 
907 	reschedule_read(fd, c, &handle_cgi_reply);
908 }
909 
910 static void
911 handle_copy(int fd, short ev, void *d)
912 {
913 	struct client *c = d;
914 	ssize_t r;
915 
916 	while (1) {
917 		while (c->len > 0) {
918 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
919 			case -1:
920 				goto end;
921 
922 			case TLS_WANT_POLLOUT:
923 				reschedule_write(c->fd, c, &handle_copy);
924 				return;
925 
926 			case TLS_WANT_POLLIN:
927 				reschedule_read(c->fd, c, &handle_copy);
928 				return;
929 
930 			default:
931                                 c->off += r;
932 				c->len -= r;
933 				break;
934 			}
935 		}
936 
937 		switch (r = read(c->pfd, c->sbuf, sizeof(c->sbuf))) {
938 		case 0:
939 			goto end;
940 		case -1:
941 			if (errno == EAGAIN || errno == EWOULDBLOCK) {
942 				reschedule_read(c->pfd, c, &handle_copy);
943 				return;
944 			}
945 			goto end;
946 		default:
947 			c->len = r;
948 			c->off = 0;
949 		}
950 	}
951 
952 end:
953 	close_conn(c->fd, ev, d);
954 }
955 
956 static void
957 close_conn(int fd, short ev, void *d)
958 {
959 	struct client *c = d;
960 
961 	switch (tls_close(c->ctx)) {
962 	case TLS_WANT_POLLIN:
963 		reschedule_read(fd, c, &close_conn);
964 		return;
965 	case TLS_WANT_POLLOUT:
966 		reschedule_read(fd, c, &close_conn);
967 		return;
968 	}
969 
970 	connected_clients--;
971 
972 	tls_free(c->ctx);
973 	c->ctx = NULL;
974 
975 	if (c->pfd != -1)
976 		close(c->pfd);
977 
978 	if (c->dir != NULL)
979 		closedir(c->dir);
980 
981 	close(c->fd);
982 	c->fd = -1;
983 }
984 
985 static void
986 do_accept(int sock, short et, void *d)
987 {
988 	struct client *c;
989 	struct server *s = d;
990 	struct sockaddr_storage addr;
991 	struct sockaddr *saddr;
992 	socklen_t len;
993 	int i, fd;
994 
995 	(void)et;
996 
997 
998 	saddr = (struct sockaddr*)&addr;
999 	len = sizeof(addr);
1000 	if ((fd = accept(sock, saddr, &len)) == -1) {
1001 		if (errno == EWOULDBLOCK || errno == EAGAIN)
1002 			return;
1003 		fatal("accept: %s", strerror(errno));
1004 	}
1005 
1006 	mark_nonblock(fd);
1007 
1008 	for (i = 0; i < MAX_USERS; ++i) {
1009 		c = &s->clients[i];
1010 		if (c->fd == -1) {
1011 			memset(c, 0, sizeof(*c));
1012 			if (tls_accept_socket(s->ctx, &c->ctx, fd) == -1)
1013 				break; /* goodbye fd! */
1014 
1015 			c->fd = fd;
1016 			c->pfd = -1;
1017 			c->dir = NULL;
1018 			c->addr = addr;
1019 
1020 			reschedule_read(fd, c, &handle_handshake);
1021 			connected_clients++;
1022 			return;
1023 		}
1024 	}
1025 
1026 	close(fd);
1027 }
1028 
1029 static void
1030 handle_sighup(int fd, short ev, void *d)
1031 {
1032 	(void)fd;
1033 	(void)ev;
1034 
1035 	event_del(&e4);
1036 	if (has_ipv6)
1037 		event_del(&e6);
1038 	if (has_siginfo)
1039 		signal_del(&siginfo);
1040 	signal_del(&sigusr2);
1041 	signal_del(&sighup);
1042 }
1043 
1044 static void
1045 handle_siginfo(int fd, short ev, void *d)
1046 {
1047 	(void)fd;
1048 	(void)ev;
1049 	(void)d;
1050 
1051 	log_info(NULL, "%d connected clients", connected_clients);
1052 }
1053 
1054 void
1055 loop(struct tls *ctx, int sock4, int sock6)
1056 {
1057 	struct server server;
1058 	size_t i;
1059 
1060 	event_init();
1061 
1062 	memset(&server, 0, sizeof(server));
1063 	for (i = 0; i < MAX_USERS; ++i)
1064 		server.clients[i].fd = -1;
1065 
1066 	event_set(&e4, sock4, EV_READ | EV_PERSIST, &do_accept, &server);
1067 	event_add(&e4, NULL);
1068 
1069 	if (sock6 != -1) {
1070 		has_ipv6 = 1;
1071 		event_set(&e6, sock6, EV_READ | EV_PERSIST, &do_accept, &server);
1072 		event_add(&e6, NULL);
1073 	}
1074 
1075 	signal_set(&sighup, SIGHUP, &handle_sighup, NULL);
1076 	signal_add(&sighup, NULL);
1077 
1078 #ifdef SIGINFO
1079 	has_siginfo = 1;
1080 	signal_set(&siginfo, SIGINFO, &handle_siginfo, NULL);
1081 	signal_add(&siginfo, NULL);
1082 #endif
1083 	signal_set(&sigusr2, SIGUSR2, &handle_siginfo, NULL);
1084 	signal_add(&sigusr2, NULL);
1085 
1086 	server.ctx = ctx;
1087 
1088 	sandbox();
1089 	event_dispatch();
1090 	_exit(0);
1091 }