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 
37 	if (v == NULL || path == NULL)
38 		return NULL;
39 
40 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
41 		if (!fnmatch(loc->match, path, 0)) {
42 			if (loc->lang != NULL)
43 				return loc->lang;
44 		}
45 	}
46 
47 	return v->locations[0].lang;
48 }
49 
50 const char *
51 vhost_default_mime(struct vhost *v, const char *path)
52 {
53 	struct location *loc;
54 	const char *default_mime = "application/octet-stream";
55 
56 	if (v == NULL || path == NULL)
57 		return default_mime;
58 
59 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
60 		if (!fnmatch(loc->match, path, 0)) {
61 			if (loc->default_mime != NULL)
62 				return loc->default_mime;
63 		}
64 	}
65 
66 	if (v->locations[0].default_mime != NULL)
67 		return v->locations[0].default_mime;
68 	return default_mime;
69 }
70 
71 const char *
72 vhost_index(struct vhost *v, const char *path)
73 {
74 	struct location *loc;
75 	const char *index = "index.gmi";
76 
77 	if (v == NULL || path == NULL)
78 		return index;
79 
80 	for (loc = &v->locations[1]; loc->match != NULL; ++loc) {
81 		if (!fnmatch(loc->match, path, 0)) {
82 			if (loc->index != NULL)
83 				return loc->index;
84 		}
85 	}
86 
87 	if (v->locations[0].index != NULL)
88 		return v->locations[0].index;
89 	return index;
90 }
91 
92 int
93 vhost_auto_index(struct vhost *v, const char *path)
94 {
95 	struct location *loc;
96 
97 	if (v == NULL || path == NULL)
98 		return 0;
99 
100 	for (loc = v->locations; loc->match != NULL; ++loc) {
101 		if (!fnmatch(loc->match, path, 0)) {
102 			if (loc->auto_index != 0)
103 				return loc->auto_index == 1;
104 		}
105 	}
106 
107 	return v->locations[0].auto_index == 1;
108 }
109 
110 int
111 check_path(struct client *c, const char *path, int *fd)
112 {
113 	struct stat sb;
114 	const char *p;
115 	int flags;
116 
117 	assert(path != NULL);
118 
119 	if (*path == '\0')
120 		p = ".";
121 	else if (*path == '/')
122 		/* in send_dir we add an initial / (to be
123 		 * redirect-friendly), but here we want to skip it */
124 		p = path+1;
125 	else
126 		p = path;
127 
128 	flags = O_RDONLY | O_NOFOLLOW;
129 
130 	if (*fd == -1 && (*fd = openat(c->host->dirfd, p, flags)) == -1)
131 		return FILE_MISSING;
132 
133 	if (fstat(*fd, &sb) == -1) {
134 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
135 		return FILE_MISSING;
136 	}
137 
138 	if (S_ISDIR(sb.st_mode))
139 		return FILE_DIRECTORY;
140 
141 	if (sb.st_mode & S_IXUSR)
142 		return FILE_EXECUTABLE;
143 
144 	return FILE_EXISTS;
145 }
146 
147 void
148 open_file(struct pollfd *fds, struct client *c)
149 {
150 	switch (check_path(c, c->iri.path, &c->fd)) {
151 	case FILE_EXECUTABLE:
152 		if (starts_with(c->iri.path, c->host->cgi)) {
153 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
154 			return;
155 		}
156 
157 		/* fallthrough */
158 
159 	case FILE_EXISTS:
160 		load_file(fds, c);
161 		return;
162 
163 	case FILE_DIRECTORY:
164 		open_dir(fds, c);
165 		return;
166 
167 	case FILE_MISSING:
168 		if (c->host->cgi != NULL && starts_with(c->iri.path, c->host->cgi)) {
169 			check_for_cgi(c->iri.path, c->iri.query, fds, c);
170 			return;
171 		}
172 		start_reply(fds, c, NOT_FOUND, "not found");
173 		return;
174 
175 	default:
176 		/* unreachable */
177 		abort();
178 	}
179 }
180 
181 void
182 load_file(struct pollfd *fds, struct client *c)
183 {
184 	if ((c->len = filesize(c->fd)) == -1) {
185 		LOGE(c, "failed to get file size for %s", c->iri.path);
186 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
187 		return;
188 	}
189 
190 	if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
191 		    c->fd, 0)) == MAP_FAILED) {
192 		LOGW(c, "mmap: %s: %s", c->iri.path, strerror(errno));
193 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
194 		return;
195 	}
196 	c->i = c->buf;
197 	c->next = S_SENDING_FILE;
198 	start_reply(fds, c, SUCCESS, mime(c->host, c->iri.path));
199 }
200 
201 /*
202  * the inverse of this algorithm, i.e. starting from the start of the
203  * path + strlen(cgi), and checking if each component, should be
204  * faster.  But it's tedious to write.  This does the opposite: starts
205  * from the end and strip one component at a time, until either an
206  * executable is found or we emptied the path.
207  */
208 void
209 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
210 {
211 	char *end;
212 	end = strchr(path, '\0');
213 
214 	/* NB: assume CGI is enabled and path matches cgi */
215 
216 	while (end > path) {
217 		/* go up one level.  UNIX paths are simple and POSIX
218 		 * dirname, with its ambiguities on if the given path
219 		 * is changed or not, gives me headaches. */
220 		while (*end != '/')
221 			end--;
222 		*end = '\0';
223 
224 		switch (check_path(c, path, &c->fd)) {
225 		case FILE_EXECUTABLE:
226 			start_cgi(path, end+1, query, fds,c);
227 			return;
228 		case FILE_MISSING:
229 			break;
230 		default:
231 			goto err;
232 		}
233 
234 		*end = '/';
235 		end--;
236 	}
237 
238 err:
239 	start_reply(fds, c, NOT_FOUND, "not found");
240 	return;
241 }
242 
243 void
244 mark_nonblock(int fd)
245 {
246 	int flags;
247 
248 	if ((flags = fcntl(fd, F_GETFL)) == -1)
249 		fatal("fcntl(F_GETFL): %s", strerror(errno));
250 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
251 		fatal("fcntl(F_SETFL): %s", strerror(errno));
252 }
253 
254 void
255 handle_handshake(struct pollfd *fds, struct client *c)
256 {
257 	struct vhost *h;
258 	const char *servname;
259 	const char *parse_err = "unknown error";
260 
261 	switch (tls_handshake(c->ctx)) {
262 	case 0:  /* success */
263 	case -1: /* already handshaked */
264 		break;
265 	case TLS_WANT_POLLIN:
266 		fds->events = POLLIN;
267 		return;
268 	case TLS_WANT_POLLOUT:
269 		fds->events = POLLOUT;
270 		return;
271 	default:
272 		/* unreachable */
273 		abort();
274 	}
275 
276 	servname = tls_conn_servername(c->ctx);
277 	if (!puny_decode(servname, c->domain, sizeof(c->domain), &parse_err)) {
278 		LOGI(c, "%s", parse_err);
279 		goto err;
280 	}
281 
282 	for (h = hosts; h->domain != NULL; ++h) {
283 		if (!fnmatch(h->domain, c->domain, 0))
284 			break;
285 	}
286 
287 	/* LOGD(c, "handshake: SNI: \"%s\"; decoded: \"%s\"; matched: \"%s\"", */
288 	/*     servname != NULL ? servname : "(null)", */
289 	/*     c->domain, */
290 	/*     h->domain != NULL ? h->domain : "(null)"); */
291 
292 	if (h->domain != NULL) {
293 		c->state = S_OPEN;
294 		c->host = h;
295 		handle_open_conn(fds, c);
296 		return;
297 	}
298 
299 err:
300 	if (servname != NULL)
301 		strncpy(c->req, servname, sizeof(c->req));
302 	else
303 		strncpy(c->req, "null", sizeof(c->req));
304 
305 	start_reply(fds, c, BAD_REQUEST, "Wrong/malformed host or missing SNI");
306 }
307 
308 void
309 handle_open_conn(struct pollfd *fds, struct client *c)
310 {
311 	const char *parse_err = "invalid request";
312 	char decoded[DOMAIN_NAME_LEN];
313 
314 	bzero(c->req, sizeof(c->req));
315 	bzero(&c->iri, sizeof(c->iri));
316 
317 	switch (tls_read(c->ctx, c->req, sizeof(c->req)-1)) {
318 	case -1:
319 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
320 		close_conn(fds, c);
321 		return;
322 
323 	case TLS_WANT_POLLIN:
324 		fds->events = POLLIN;
325 		return;
326 
327 	case TLS_WANT_POLLOUT:
328 		fds->events = POLLOUT;
329 		return;
330 	}
331 
332 	if (!trim_req_iri(c->req, &parse_err)
333 	    || !parse_iri(c->req, &c->iri, &parse_err)
334 	    || !puny_decode(c->iri.host, decoded, sizeof(decoded), &parse_err)) {
335 		LOGI(c, "iri parse error: %s", parse_err);
336 		start_reply(fds, c, BAD_REQUEST, "invalid request");
337 		return;
338 	}
339 
340 	if (c->iri.port_no != conf.port
341 	    || strcmp(c->iri.schema, "gemini")
342 	    || strcmp(decoded, c->domain)) {
343 		start_reply(fds, c, PROXY_REFUSED, "won't proxy request");
344 		return;
345 	}
346 
347 	open_file(fds, c);
348 }
349 
350 void
351 start_reply(struct pollfd *pfd, struct client *c, int code, const char *meta)
352 {
353 	char buf[1030];		/* status + ' ' + max reply len + \r\n\0 */
354 	const char *lang;
355 	size_t len;
356 
357 	c->code = code;
358 	c->meta = meta;
359 	c->state = S_INITIALIZING;
360 
361 	lang = vhost_lang(c->host, c->iri.path);
362 
363 	snprintf(buf, sizeof(buf), "%d ", code);
364 	strlcat(buf, meta, sizeof(buf));
365 	if (!strcmp(meta, "text/gemini") && lang != NULL) {
366 		strlcat(buf, "; lang=", sizeof(buf));
367 		strlcat(buf, lang, sizeof(buf));
368 	}
369 
370 	len = strlcat(buf, "\r\n", sizeof(buf));
371 	assert(len < sizeof(buf));
372 
373 	switch (tls_write(c->ctx, buf, len)) {
374 	case -1:
375 		close_conn(pfd, c);
376 		return;
377 	case TLS_WANT_POLLIN:
378 		pfd->events = POLLIN;
379 		return;
380 	case TLS_WANT_POLLOUT:
381 		pfd->events = POLLOUT;
382 		return;
383 	}
384 
385 	log_request(c, buf, sizeof(buf));
386 
387 	/* we don't need a body */
388 	if (c->code != SUCCESS) {
389 		close_conn(pfd, c);
390 		return;
391 	}
392 
393 	/* advance the state machine */
394 	c->state = c->next;
395 	handle(pfd, c);
396 }
397 
398 void
399 start_cgi(const char *spath, const char *relpath, const char *query,
400     struct pollfd *fds, struct client *c)
401 {
402 	char addr[NI_MAXHOST];
403 	const char *ruser, *cissuer, *chash;
404 	int e;
405 
406 	e = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
407 	    addr, sizeof(addr),
408 	    NULL, 0,
409 	    NI_NUMERICHOST);
410 	if (e != 0)
411 		goto err;
412 
413 	if (tls_peer_cert_provided(c->ctx)) {
414 		ruser = tls_peer_cert_subject(c->ctx);
415 		cissuer = tls_peer_cert_issuer(c->ctx);
416 		chash = tls_peer_cert_hash(c->ctx);
417 	} else {
418 		ruser = NULL;
419 		cissuer = NULL;
420 		chash = NULL;
421 	}
422 
423 	if (!send_string(exfd, spath)
424 	    || !send_string(exfd, relpath)
425 	    || !send_string(exfd, query)
426 	    || !send_string(exfd, addr)
427 	    || !send_string(exfd, ruser)
428 	    || !send_string(exfd, cissuer)
429 	    || !send_string(exfd, chash)
430 	    || !send_vhost(exfd, c->host))
431 		goto err;
432 
433 	close(c->fd);
434 	if ((c->fd = recv_fd(exfd)) == -1) {
435 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
436 		return;
437 	}
438 	c->state = S_SENDING_CGI;
439 	cgi_poll_on_child(fds, c);
440 	c->code = -1;
441 	/* handle_cgi(fds, c); */
442 	return;
443 
444 err:
445 	/* fatal("cannot talk to the executor process: %s", strerror(errno)); */
446 	fatal("cannot talk to the executor process");
447 }
448 
449 void
450 send_file(struct pollfd *fds, struct client *c)
451 {
452 	ssize_t ret, len;
453 
454 	/* ensure the correct state */
455 	c->state = S_SENDING_FILE;
456 
457 	len = (c->buf + c->len) - c->i;
458 
459 	while (len > 0) {
460 		switch (ret = tls_write(c->ctx, c->i, len)) {
461 		case -1:
462 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
463 			close_conn(fds, c);
464 			return;
465 
466 		case TLS_WANT_POLLIN:
467 			fds->events = POLLIN;
468 			return;
469 
470 		case TLS_WANT_POLLOUT:
471 			fds->events = POLLOUT;
472 			return;
473 
474 		default:
475 			c->i += ret;
476 			len -= ret;
477 			break;
478 		}
479 	}
480 
481 	close_conn(fds, c);
482 }
483 
484 void
485 open_dir(struct pollfd *fds, struct client *c)
486 {
487 	size_t len;
488 	int dirfd;
489 	char *before_file;
490 
491 	len = strlen(c->iri.path);
492 	if (len > 0 && !ends_with(c->iri.path, "/")) {
493 		redirect_canonical_dir(fds, c);
494 		return;
495 	}
496 
497 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
498 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
499 	if (!ends_with(c->sbuf, "/"))
500 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
501 	before_file = strchr(c->sbuf, '\0');
502 	len = strlcat(c->sbuf, vhost_index(c->host, c->iri.path),
503 	    sizeof(c->sbuf));
504 	if (len >= sizeof(c->sbuf)) {
505 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
506 		return;
507 	}
508 
509 	c->iri.path = c->sbuf;
510 
511 	/* close later unless we have to generate the dir listing */
512 	dirfd = c->fd;
513 	c->fd = -1;
514 
515 	switch (check_path(c, c->iri.path, &c->fd)) {
516 	case FILE_EXECUTABLE:
517 		if (starts_with(c->iri.path, c->host->cgi)) {
518 			start_cgi(c->iri.path, "", c->iri.query, fds, c);
519 			break;
520 		}
521 
522 		/* fallthrough */
523 
524 	case FILE_EXISTS:
525                 load_file(fds, c);
526 		break;
527 
528 	case FILE_DIRECTORY:
529 		start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
530 		break;
531 
532 	case FILE_MISSING:
533 		*before_file = '\0';
534 
535 		if (!vhost_auto_index(c->host, c->iri.path)) {
536 			start_reply(fds, c, NOT_FOUND, "not found");
537 			break;
538 		}
539 
540 		c->fd = dirfd;
541 		c->next = S_SENDING_DIR;
542 
543 		if ((c->dir = fdopendir(c->fd)) == NULL) {
544 			LOGE(c, "can't fdopendir(%d) (vhost:%s) %s: %s",
545 			    c->fd, c->host->domain, c->iri.path, strerror(errno));
546 			start_reply(fds, c, TEMP_FAILURE, "internal server error");
547 			return;
548 		}
549 		c->off = 0;
550 
551                 start_reply(fds, c, SUCCESS, "text/gemini");
552 		return;
553 
554 	default:
555 		/* unreachable */
556 		abort();
557 	}
558 
559 	close(dirfd);
560 }
561 
562 void
563 redirect_canonical_dir(struct pollfd *fds, struct client *c)
564 {
565 	size_t len;
566 
567 	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
568 	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
569 	len = strlcat(c->sbuf, "/", sizeof(c->sbuf));
570 
571 	if (len >= sizeof(c->sbuf)) {
572 		start_reply(fds, c, TEMP_FAILURE, "internal server error");
573 		return;
574 	}
575 
576 	start_reply(fds, c, TEMP_REDIRECT, c->sbuf);
577 }
578 
579 int
580 read_next_dir_entry(struct client *c)
581 {
582 	struct dirent *d;
583 
584 	do {
585 		errno = 0;
586 		if ((d = readdir(c->dir)) == NULL) {
587 			if (errno != 0)
588 				LOGE(c, "readdir: %s", strerror(errno));
589 			return 0;
590 		}
591 	} while (!strcmp(d->d_name, "."));
592 
593 	/* XXX: url escape */
594 	snprintf(c->sbuf, sizeof(c->sbuf), "=> %s %s\n",
595 	    d->d_name, d->d_name);
596 	c->len = strlen(c->sbuf);
597 	c->off = 0;
598 
599 	return 1;
600 }
601 
602 void
603 send_directory_listing(struct pollfd *fds, struct client *c)
604 {
605 	ssize_t r;
606 
607 	while (1) {
608 		if (c->len == 0) {
609 			if (!read_next_dir_entry(c))
610 				goto end;
611 		}
612 
613 		while (c->len > 0) {
614 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
615 			case -1:
616 				goto end;
617 
618 			case TLS_WANT_POLLOUT:
619 				fds->events = POLLOUT;
620 				return;
621 
622 			case TLS_WANT_POLLIN:
623 				fds->events = POLLIN;
624 				return;
625 
626 			default:
627 				c->off += r;
628 				c->len -= r;
629 				break;
630 			}
631 		}
632 	}
633 
634 end:
635 	close_conn(fds, c);
636 }
637 
638 void
639 cgi_poll_on_child(struct pollfd *fds, struct client *c)
640 {
641 	int fd;
642 
643 	if (c->waiting_on_child)
644 		return;
645 	c->waiting_on_child = 1;
646 
647 	fds->events = POLLIN;
648 
649 	fd = fds->fd;
650 	fds->fd = c->fd;
651 	c->fd = fd;
652 }
653 
654 void
655 cgi_poll_on_client(struct pollfd *fds, struct client *c)
656 {
657 	int fd;
658 
659 	if (!c->waiting_on_child)
660 		return;
661 	c->waiting_on_child = 0;
662 
663 	fd = fds->fd;
664 	fds->fd = c->fd;
665 	c->fd = fd;
666 }
667 
668 /* handle the read from the child process.  Return like read(2) */
669 static ssize_t
670 read_from_cgi(struct client *c)
671 {
672 	void	*buf;
673 	size_t	 len;
674 	ssize_t	 r;
675 
676 	/* if we haven't read a whole response line, we want to
677 	 * continue reading. */
678 
679 	if (c->code == -1) {
680 		buf = c->sbuf + c->len;
681 		len = sizeof(c->sbuf) - c->len;
682 	} else {
683 		buf = c->sbuf;
684 		len = sizeof(c->sbuf);
685 	}
686 
687 	r = read(c->fd, buf, len);
688 	if (r == 0 || r == -1)
689 		return r;
690 
691 	c->len += r;
692 	c->off = 0;
693 
694 	if (c->code != -1)
695 		return r;
696 
697 	if (strchr(c->sbuf, '\n') || c->len == sizeof(c->sbuf)) {
698 		c->code = 0;
699 		log_request(c, c->sbuf, c->len);
700 	}
701 
702 	return r;
703 }
704 
705 void
706 handle_cgi(struct pollfd *fds, struct client *c)
707 {
708 	ssize_t r;
709 
710 	/* ensure c->fd is the child and fds->fd the client */
711 	cgi_poll_on_client(fds, c);
712 
713 	while (1) {
714 		if (c->code == -1 || c->len == 0) {
715 			switch (r = read_from_cgi(c)) {
716 			case 0:
717 				goto end;
718 
719 			case -1:
720 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
721 					cgi_poll_on_child(fds, c);
722 					return;
723 				}
724 				goto end;
725 			}
726 		}
727 
728 		if (c->code == -1) {
729 			cgi_poll_on_child(fds, c);
730 			return;
731 		}
732 
733 		while (c->len > 0) {
734 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
735 			case -1:
736 				goto end;
737 
738 			case TLS_WANT_POLLOUT:
739 				fds->events = POLLOUT;
740 				return;
741 
742 			case TLS_WANT_POLLIN:
743 				fds->events = POLLIN;
744 				return;
745 
746 			default:
747                                 c->off += r;
748 				c->len -= r;
749 				break;
750 			}
751 		}
752 	}
753 
754 end:
755 	close_conn(fds, c);
756 }
757 
758 void
759 close_conn(struct pollfd *pfd, struct client *c)
760 {
761 	c->state = S_CLOSING;
762 
763 	switch (tls_close(c->ctx)) {
764 	case TLS_WANT_POLLIN:
765 		pfd->events = POLLIN;
766 		return;
767 	case TLS_WANT_POLLOUT:
768 		pfd->events = POLLOUT;
769 		return;
770 	}
771 
772 	connected_clients--;
773 
774 	tls_free(c->ctx);
775 	c->ctx = NULL;
776 
777 	if (c->buf != MAP_FAILED)
778 		munmap(c->buf, c->len);
779 
780 	if (c->fd != -1)
781 		close(c->fd);
782 
783 	if (c->dir != NULL)
784 		closedir(c->dir);
785 
786 	close(pfd->fd);
787 	pfd->fd = -1;
788 }
789 
790 void
791 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
792 {
793 	int i, fd;
794 	struct sockaddr_storage addr;
795 	socklen_t len;
796 
797 	len = sizeof(addr);
798 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
799 		if (errno == EWOULDBLOCK)
800 			return;
801 		fatal("accept: %s", strerror(errno));
802 	}
803 
804 	mark_nonblock(fd);
805 
806 	for (i = 0; i < MAX_USERS; ++i) {
807 		if (fds[i].fd == -1) {
808 			bzero(&clients[i], sizeof(struct client));
809 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
810 				break; /* goodbye fd! */
811 
812 			fds[i].fd = fd;
813 			fds[i].events = POLLIN;
814 
815 			clients[i].state = S_HANDSHAKE;
816 			clients[i].next = S_SENDING_FILE;
817 			clients[i].fd = -1;
818 			clients[i].waiting_on_child = 0;
819 			clients[i].buf = MAP_FAILED;
820 			clients[i].dir = NULL;
821 			clients[i].addr = addr;
822 
823 			connected_clients++;
824 			return;
825 		}
826 	}
827 
828 	close(fd);
829 }
830 
831 void
832 handle(struct pollfd *fds, struct client *client)
833 {
834 	switch (client->state) {
835 	case S_HANDSHAKE:
836 		handle_handshake(fds, client);
837 		break;
838 
839 	case S_OPEN:
840                 handle_open_conn(fds, client);
841 		break;
842 
843 	case S_INITIALIZING:
844 		start_reply(fds, client, client->code, client->meta);
845                 break;
846 
847 	case S_SENDING_FILE:
848 		send_file(fds, client);
849 		break;
850 
851 	case S_SENDING_DIR:
852 		send_directory_listing(fds, client);
853 		break;
854 
855 	case S_SENDING_CGI:
856 		handle_cgi(fds, client);
857 		break;
858 
859 	case S_CLOSING:
860 		close_conn(fds, client);
861 		break;
862 
863 	default:
864 		/* unreachable */
865 		abort();
866 	}
867 }
868 
869 void
870 loop(struct tls *ctx, int sock4, int sock6)
871 {
872 	int i;
873 	struct client clients[MAX_USERS];
874 	struct pollfd fds[MAX_USERS];
875 
876 	connected_clients = 0;
877 
878 	for (i = 0; i < MAX_USERS; ++i) {
879 		fds[i].fd = -1;
880 		fds[i].events = POLLIN;
881 		bzero(&clients[i], sizeof(struct client));
882 	}
883 
884 	fds[0].fd = sock4;
885 	fds[1].fd = sock6;
886 
887 	for (;;) {
888 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
889 			if (errno == EINTR) {
890                                 fprintf(stderr, "connected clients: %d\n",
891 				    connected_clients);
892 				continue;
893 			}
894 			fatal("poll: %s", strerror(errno));
895 		}
896 
897 		for (i = 0; i < MAX_USERS; i++) {
898 			if (fds[i].revents == 0)
899 				continue;
900 
901 			if (fds[i].revents & (POLLERR|POLLNVAL))
902 				fatal("bad fd %d: %s", fds[i].fd,
903 				    strerror(errno));
904 
905 			if (fds[i].revents & POLLHUP) {
906 				/* fds[i] may be the fd of the stdin
907 				 * of a cgi script that has exited. */
908 				if (!clients[i].waiting_on_child) {
909 					close_conn(&fds[i], &clients[i]);
910 					continue;
911 				}
912 			}
913 
914 			if (fds[i].fd == sock4)
915 				do_accept(sock4, ctx, fds, clients);
916 			else if (fds[i].fd == sock6)
917 				do_accept(sock6, ctx, fds, clients);
918 			else
919 				handle(&fds[i], &clients[i]);
920 		}
921 	}
922 }