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Date:: Thu Dec 24 15:48:39 2020 UTC
Message:: moving declarations to header file
Actions:: History | Blame | Raw File
1 /*
2  * Copyright (c) 2020 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/socket.h>
19 #include <sys/stat.h>
20 
21 #include <assert.h>
22 #include <err.h>
23 #include <errno.h>
24 #include <fcntl.h>
25 #include <limits.h>
26 #include <signal.h>
27 #include <string.h>
28 
29 #include "gmid.h"
30 
31 const char *dir, *cgi;
32 int dirfd;
33 int port;
34 int foreground;
35 int connected_clients;
36 
37 void
38 siginfo_handler(int sig)
39 {
40 	(void)sig;
41 }
42 
43 int
44 starts_with(const char *str, const char *prefix)
45 {
46 	size_t i;
47 
48 	for (i = 0; prefix[i] != '\0'; ++i)
49 		if (str[i] != prefix[i])
50 			return 0;
51 	return 1;
52 }
53 
54 char *
55 url_after_proto(char *url)
56 {
57 	char *s;
58 	const char *proto = "gemini:";
59 	const char *marker = "//";
60 
61 	/* a relative URL */
62 	if ((s = strstr(url, marker)) == NULL)
63 		return url;
64 
65 	/*
66 	 * if a protocol is not specified, gemini should be implied:
67 	 * this handles the case of //example.com
68 	 */
69 	if (s == url)
70 		return s + strlen(marker);
71 
72 	if (s - strlen(proto) != url)
73 		return NULL;
74 
75 	if (!starts_with(url, proto))
76 		return NULL;
77 
78 	return s + strlen(marker);
79 }
80 
81 char *
82 url_start_of_request(char *url)
83 {
84 	char *s, *t;
85 
86 	if ((s = url_after_proto(url)) == NULL)
87 		return NULL;
88 
89 	/* non-absolute URL */
90 	if (s == url)
91 		return s;
92 
93 	if ((t = strstr(s, "/")) == NULL)
94 		return s + strlen(s);
95 	return t;
96 }
97 
98 int
99 url_trim(struct client *c, char *url)
100 {
101 	const char *e = "\r\n";
102 	char *s;
103 
104 	if ((s = strstr(url, e)) == NULL)
105 		return 0;
106 	s[0] = '\0';
107 	s[1] = '\0';
108 
109 	if (s[2] != '\0') {
110 		LOGE(c, "%s", "request longer than 1024 bytes");
111 		return 0;
112 	}
113 
114 	return 1;
115 }
116 
117 char *
118 adjust_path(char *path)
119 {
120 	char *s, *query;
121 	size_t len;
122 
123 	if ((query = strchr(path, '?')) != NULL) {
124 		*query = '\0';
125 		query++;
126 	}
127 
128 	/* /.. -> / */
129 	len = strlen(path);
130 	if (len >= 3) {
131 		if (!strcmp(&path[len-3], "/..")) {
132 			path[len-2] = '\0';
133 		}
134 	}
135 
136 	/* if the path is only `..` trim out and exit */
137 	if (!strcmp(path, "..")) {
138 		path[0] = '\0';
139 		return query;
140 	}
141 
142 	/* remove every ../ in the path */
143 	while (1) {
144 		if ((s = strstr(path, "../")) == NULL)
145 			return query;
146 		memmove(s, s+3, strlen(s)+1);	/* copy also the \0 */
147 	}
148 }
149 
150 int
151 start_reply(struct pollfd *pfd, struct client *client, int code, const char *reason)
152 {
153 	char buf[1030] = {0}; 	/* status + ' ' + max reply len + \r\n\0 */
154 	int len;
155 	int ret;
156 
157 	client->code = code;
158 	client->meta = reason;
159 	client->state = S_INITIALIZING;
160 
161 	len = snprintf(buf, sizeof(buf), "%d %s\r\n", code, reason);
162 	assert(len < (int)sizeof(buf));
163 	ret = tls_write(client->ctx, buf, len);
164 	if (ret == TLS_WANT_POLLIN) {
165 		pfd->events = POLLIN;
166 		return 0;
167 	}
168 
169 	if (ret == TLS_WANT_POLLOUT) {
170 		pfd->events = POLLOUT;
171 		return 0;
172 	}
173 
174 	return 1;
175 }
176 
177 ssize_t
178 filesize(int fd)
179 {
180 	ssize_t len;
181 
182 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
183 		return -1;
184 	if (lseek(fd, 0, SEEK_SET) == -1)
185 		return -1;
186 	return len;
187 }
188 
189 const char *
190 path_ext(const char *path)
191 {
192 	const char *end;
193 
194 	end = path + strlen(path)-1; /* the last byte before the NUL */
195 	for (; end != path; --end) {
196 		if (*end == '.')
197 			return end+1;
198 		if (*end == '/')
199 			break;
200 	}
201 
202 	return NULL;
203 }
204 
205 const char *
206 mime(const char *path)
207 {
208 	const char *ext, *def = "application/octet-stream";
209 	struct etm *t;
210 
211 	if ((ext = path_ext(path)) == NULL)
212 		return def;
213 
214 	for (t = filetypes; t->mime != NULL; ++t)
215 		if (!strcmp(ext, t->ext))
216 			return t->mime;
217 
218 	return def;
219 }
220 
221 int
222 check_path(struct client *c, const char *path, int *fd)
223 {
224 	struct stat sb;
225 
226 	assert(path != NULL);
227 	if ((*fd = openat(dirfd, path,
228 		    O_RDONLY | O_NOFOLLOW | O_CLOEXEC)) == -1) {
229 		return FILE_MISSING;
230 	}
231 
232 	if (fstat(*fd, &sb) == -1) {
233 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
234 		return FILE_MISSING;
235 	}
236 
237 	if (S_ISDIR(sb.st_mode))
238 		return FILE_DIRECTORY;
239 
240 	if (sb.st_mode & S_IXUSR)
241 		return FILE_EXECUTABLE;
242 
243 	return FILE_EXISTS;
244 }
245 
246 /*
247  * the inverse of this algorithm, i.e. starting from the start of the
248  * path + strlen(cgi), and checking if each component, should be
249  * faster.  But it's tedious to write.  This does the opposite: starts
250  * from the end and strip one component at a time, until either an
251  * executable is found or we emptied the path.
252  */
253 int
254 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
255 {
256 	char *end;
257 	end = strchr(path, '\0');
258 
259 	/* NB: assume CGI is enabled and path matches cgi */
260 
261 	while (end > path) {
262 		/* go up one level.  UNIX paths are simple and POSIX
263 		 * dirname, with its ambiguities on if the given path
264 		 * is changed or not, gives me headaches. */
265 		while (*end != '/')
266 			end--;
267 		*end = '\0';
268 
269 		switch (check_path(c, path, &c->fd)) {
270 		case FILE_EXECUTABLE:
271 			return start_cgi(path, end+1, query, fds,c);
272 		case FILE_MISSING:
273 			break;
274 		default:
275 			goto err;
276 		}
277 
278 		*end = '/';
279 		end--;
280 	}
281 
282 err:
283 	if (!start_reply(fds, c, NOT_FOUND, "not found"))
284 		return 0;
285 	goodbye(fds, c);
286 	return 0;
287 }
288 
289 
290 int
291 open_file(char *path, char *query, struct pollfd *fds, struct client *c)
292 {
293 	char fpath[PATHBUF];
294 
295 	bzero(fpath, sizeof(fpath));
296 
297 	if (*path != '.')
298 		fpath[0] = '.';
299 	strlcat(fpath, path, PATHBUF);
300 
301 	switch (check_path(c, fpath, &c->fd)) {
302 	case FILE_EXECUTABLE:
303 		/* +2 to skip the ./ */
304 		if (cgi != NULL && starts_with(fpath+2, cgi))
305 			return start_cgi(fpath, "", query, fds, c);
306 
307 		/* fallthrough */
308 
309 	case FILE_EXISTS:
310 		if ((c->len = filesize(c->fd)) == -1) {
311 			LOGE(c, "failed to get file size for %s", fpath);
312 			goodbye(fds, c);
313 			return 0;
314 		}
315 
316 		if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
317 			    c->fd, 0)) == MAP_FAILED) {
318 			warn("mmap: %s", fpath);
319 			goodbye(fds, c);
320 			return 0;
321 		}
322 		c->i = c->buf;
323 		return start_reply(fds, c, SUCCESS, mime(fpath));
324 
325 	case FILE_DIRECTORY:
326 		LOGD(c, "%s is a directory, trying %s/index.gmi", fpath, fpath);
327 		close(c->fd);
328 		c->fd = -1;
329 		send_dir(fpath, fds, c);
330 		return 0;
331 
332 	case FILE_MISSING:
333 		if (cgi != NULL && starts_with(fpath+2, cgi))
334 			return check_for_cgi(fpath, query, fds, c);
335 
336 		if (!start_reply(fds, c, NOT_FOUND, "not found"))
337 			return 0;
338 		goodbye(fds, c);
339 		return 0;
340 
341 	default:
342 		/* unreachable */
343 		abort();
344 	}
345 }
346 
347 int
348 start_cgi(const char *spath, const char *relpath, const char *query,
349     struct pollfd *fds, struct client *c)
350 {
351 	pid_t pid;
352 	int p[2]; 		/* read end, write end */
353 
354 	if (pipe(p) == -1)
355 		goto err;
356 
357 	switch (pid = fork()) {
358 	case -1:
359 		goto err;
360 
361 	case 0: { 		/* child */
362 		char *ex, *requri, *portno;
363 		char addr[INET_ADDRSTRLEN];
364 		char *argv[] = { NULL, NULL, NULL };
365 
366 		spath++;
367 
368 		close(p[0]);
369 		if (dup2(p[1], 1) == -1)
370 			goto childerr;
371 
372 		if (inet_ntop(c->af, &c->addr, addr, sizeof(addr)) == NULL)
373 			goto childerr;
374 
375 		if (asprintf(&portno, "%d", port) == -1)
376 			goto childerr;
377 
378 		if (asprintf(&ex, "%s%s", dir, spath+1) == -1)
379 			goto childerr;
380 
381 		if (asprintf(&requri, "%s%s%s", spath,
382 		    *relpath == '\0' ? "" : "/",
383 		    relpath) == -1)
384 			goto childerr;
385 
386 		argv[0] = argv[1] = ex;
387 
388 		/* fix the env */
389 		SAFE_SETENV("GATEWAY_INTERFACE", "CGI/1.1");
390 		SAFE_SETENV("SERVER_SOFTWARE", "gmid");
391 		SAFE_SETENV("SERVER_PORT", portno);
392 		/* setenv("SERVER_NAME", "", 1); */
393 		SAFE_SETENV("SCRIPT_NAME", spath);
394 		SAFE_SETENV("SCRIPT_EXECUTABLE", ex);
395 		SAFE_SETENV("REQUEST_URI", requri);
396 		SAFE_SETENV("REQUEST_RELATIVE", relpath);
397 		SAFE_SETENV("QUERY_STRING", query);
398 		SAFE_SETENV("REMOTE_HOST", addr);
399 		SAFE_SETENV("REMOTE_ADDR", addr);
400 		SAFE_SETENV("DOCUMENT_ROOT", dir);
401 
402 		if (tls_peer_cert_provided(c->ctx)) {
403 			SAFE_SETENV("AUTH_TYPE", "Certificate");
404 			SAFE_SETENV("REMOTE_USER", tls_peer_cert_subject(c->ctx));
405 			SAFE_SETENV("TLS_CLIENT_ISSUER", tls_peer_cert_issuer(c->ctx));
406 			SAFE_SETENV("TLS_CLIENT_HASH", tls_peer_cert_hash(c->ctx));
407 		}
408 
409 		execvp(ex, argv);
410 		goto childerr;
411 	}
412 
413 	default:		/* parent */
414 		close(p[1]);
415 		close(c->fd);
416 		c->fd = p[0];
417 		c->child = pid;
418 		mark_nonblock(c->fd);
419 		c->state = S_SENDING;
420 		handle_cgi(fds, c);
421 		return 0;
422 	}
423 
424 err:
425 	if (!start_reply(fds, c, TEMP_FAILURE, "internal server error"))
426 		return 0;
427 	goodbye(fds, c);
428 	return 0;
429 
430 childerr:
431 	dprintf(p[1], "%d internal server error\r\n", TEMP_FAILURE);
432 	close(p[1]);
433 	_exit(1);
434 }
435 
436 void
437 cgi_setpoll_on_child(struct pollfd *fds, struct client *c)
438 {
439 	int fd;
440 
441 	if (c->waiting_on_child)
442 		return;
443 	c->waiting_on_child = 1;
444 
445 	fds->events = POLLIN;
446 
447 	fd = fds->fd;
448 	fds->fd = c->fd;
449 	c->fd = fd;
450 }
451 
452 void
453 cgi_setpoll_on_client(struct pollfd *fds, struct client *c)
454 {
455 	int fd;
456 
457 	if (!c->waiting_on_child)
458 		return;
459 	c->waiting_on_child = 0;
460 
461 	fd = fds->fd;
462 	fds->fd = c->fd;
463 	c->fd = fd;
464 }
465 
466 void
467 handle_cgi(struct pollfd *fds, struct client *c)
468 {
469 	ssize_t r;
470 
471 	/* ensure c->fd is the child and fds->fd the client */
472 	cgi_setpoll_on_client(fds, c);
473 
474 	while (1) {
475 		if (c->len == 0) {
476 			if ((r = read(c->fd, c->sbuf, sizeof(c->sbuf))) == 0)
477 				goto end;
478 			if (r == -1) {
479 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
480 					cgi_setpoll_on_child(fds, c);
481 					return;
482 				}
483                                 goto end;
484 			}
485 			c->len = r;
486 			c->off = 0;
487 		}
488 
489 		while (c->len > 0) {
490 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
491 			case -1:
492 				goto end;
493 
494 			case TLS_WANT_POLLOUT:
495 				fds->events = POLLOUT;
496 				return;
497 
498 			case TLS_WANT_POLLIN:
499 				fds->events = POLLIN;
500 				return;
501 
502 			default:
503                                 c->off += r;
504 				c->len -= r;
505 				break;
506 			}
507 		}
508 	}
509 
510 end:
511 	goodbye(fds, c);
512 }
513 
514 void
515 send_file(char *path, char *query, struct pollfd *fds, struct client *c)
516 {
517 	ssize_t ret, len;
518 
519 	if (c->fd == -1) {
520 		if (!open_file(path, query, fds, c))
521 			return;
522 		c->state = S_SENDING;
523 	}
524 
525 	len = (c->buf + c->len) - c->i;
526 
527 	while (len > 0) {
528 		switch (ret = tls_write(c->ctx, c->i, len)) {
529 		case -1:
530 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
531 			goodbye(fds, c);
532 			return;
533 
534 		case TLS_WANT_POLLIN:
535 			fds->events = POLLIN;
536 			return;
537 
538 		case TLS_WANT_POLLOUT:
539 			fds->events = POLLOUT;
540 			return;
541 
542 		default:
543 			c->i += ret;
544 			len -= ret;
545 			break;
546 		}
547 	}
548 
549 	goodbye(fds, c);
550 }
551 
552 void
553 send_dir(char *path, struct pollfd *fds, struct client *client)
554 {
555 	char fpath[PATHBUF];
556 	size_t len;
557 
558 	bzero(fpath, PATHBUF);
559 
560 	if (path[0] != '.')
561 		fpath[0] = '.';
562 
563 	/* this cannot fail since sizeof(fpath) > maxlen of path */
564 	strlcat(fpath, path, PATHBUF);
565 	len = strlen(fpath);
566 
567 	/* add a trailing / in case. */
568 	if (fpath[len-1] != '/') {
569 		fpath[len] = '/';
570 	}
571 
572 	strlcat(fpath, "index.gmi", sizeof(fpath));
573 
574 	send_file(fpath, NULL, fds, client);
575 }
576 
577 void
578 handle(struct pollfd *fds, struct client *client)
579 {
580 	char buf[GEMINI_URL_LEN];
581 	char *path;
582 	char *query;
583 
584 	switch (client->state) {
585 	case S_OPEN:
586 		bzero(buf, GEMINI_URL_LEN);
587 		switch (tls_read(client->ctx, buf, sizeof(buf)-1)) {
588 		case -1:
589 			LOGE(client, "tls_read: %s", tls_error(client->ctx));
590 			goodbye(fds, client);
591 			return;
592 
593 		case TLS_WANT_POLLIN:
594 			fds->events = POLLIN;
595 			return;
596 
597 		case TLS_WANT_POLLOUT:
598 			fds->events = POLLOUT;
599 			return;
600 		}
601 
602 		if (!url_trim(client, buf)) {
603 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
604 				return;
605 			goodbye(fds, client);
606 			return;
607 		}
608 
609 		if ((path = url_start_of_request(buf)) == NULL) {
610 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
611 				return;
612 			goodbye(fds, client);
613 			return;
614 		}
615 
616 		query = adjust_path(path);
617 		LOGI(client, "GET %s%s%s", path,
618 		    query ? "?" : "",
619 		    query ? query : "");
620 
621 		send_file(path, query, fds, client);
622 		break;
623 
624 	case S_INITIALIZING:
625 		if (!start_reply(fds, client, client->code, client->meta))
626 			return;
627 
628 		if (client->code != SUCCESS) {
629 			/* we don't need a body */
630 			goodbye(fds, client);
631 			return;
632 		}
633 
634 		client->state = S_SENDING;
635 
636 		/* fallthrough */
637 
638 	case S_SENDING:
639 		if (client->child != -1)
640 			handle_cgi(fds, client);
641 		else
642 			send_file(NULL, NULL, fds, client);
643 		break;
644 
645 	case S_CLOSING:
646 		goodbye(fds, client);
647 		break;
648 
649 	default:
650 		/* unreachable */
651 		abort();
652 	}
653 }
654 
655 void
656 mark_nonblock(int fd)
657 {
658 	int flags;
659 
660 	if ((flags = fcntl(fd, F_GETFL)) == -1)
661 		FATAL("fcntl(F_GETFL): %s", strerror(errno));
662 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
663 		FATAL("fcntl(F_SETFL): %s", strerror(errno));
664 }
665 
666 int
667 make_socket(int port, int family)
668 {
669 	int sock, v;
670 	struct sockaddr_in addr4;
671 	struct sockaddr_in6 addr6;
672 	struct sockaddr *addr;
673 	socklen_t len;
674 
675         switch (family) {
676 	case AF_INET:
677 		bzero(&addr4, sizeof(addr4));
678 		addr4.sin_family = family;
679 		addr4.sin_port = htons(port);
680 		addr4.sin_addr.s_addr = INADDR_ANY;
681 		addr = (struct sockaddr*)&addr4;
682 		len = sizeof(addr4);
683 		break;
684 
685 	case AF_INET6:
686 		bzero(&addr6, sizeof(addr6));
687 		addr6.sin6_family = AF_INET6;
688 		addr6.sin6_port = htons(port);
689 		addr6.sin6_addr = in6addr_any;
690 		addr = (struct sockaddr*)&addr6;
691 		len = sizeof(addr6);
692 		break;
693 
694 	default:
695 		/* unreachable */
696 		abort();
697 	}
698 
699 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
700 		FATAL("socket: %s", strerror(errno));
701 
702 	v = 1;
703 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
704 		FATAL("setsockopt(SO_REUSEADDR): %s", strerror(errno));
705 
706 	v = 1;
707 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
708 		FATAL("setsockopt(SO_REUSEPORT): %s", strerror(errno));
709 
710 	mark_nonblock(sock);
711 
712 	if (bind(sock, addr, len) == -1)
713 		FATAL("bind: %s", strerror(errno));
714 
715 	if (listen(sock, 16) == -1)
716 		FATAL("listen: %s", strerror(errno));
717 
718 	return sock;
719 }
720 
721 void
722 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
723 {
724 	int i, fd;
725 	struct sockaddr_in addr;
726 	socklen_t len;
727 
728 	len = sizeof(addr);
729 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
730 		if (errno == EWOULDBLOCK)
731 			return;
732 		FATAL("accept: %s", strerror(errno));
733 	}
734 
735 	mark_nonblock(fd);
736 
737 	for (i = 0; i < MAX_USERS; ++i) {
738 		if (fds[i].fd == -1) {
739 			bzero(&clients[i], sizeof(struct client));
740 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
741 				break; /* goodbye fd! */
742 
743 			fds[i].fd = fd;
744 			fds[i].events = POLLIN;
745 
746 			clients[i].state = S_OPEN;
747 			clients[i].fd = -1;
748 			clients[i].child = -1;
749 			clients[i].buf = MAP_FAILED;
750 			clients[i].af = AF_INET;
751 			clients[i].addr = addr.sin_addr;
752 
753 			connected_clients++;
754 			return;
755 		}
756 	}
757 
758 	close(fd);
759 }
760 
761 void
762 goodbye(struct pollfd *pfd, struct client *c)
763 {
764 	ssize_t ret;
765 
766 	c->state = S_CLOSING;
767 
768 	ret = tls_close(c->ctx);
769 	if (ret == TLS_WANT_POLLIN) {
770 		pfd->events = POLLIN;
771 		return;
772 	}
773 	if (ret == TLS_WANT_POLLOUT) {
774 		pfd->events = POLLOUT;
775 		return;
776 	}
777 
778 	connected_clients--;
779 
780 	tls_free(c->ctx);
781 	c->ctx = NULL;
782 
783 	if (c->buf != MAP_FAILED)
784 		munmap(c->buf, c->len);
785 
786 	if (c->fd != -1)
787 		close(c->fd);
788 
789 	close(pfd->fd);
790 	pfd->fd = -1;
791 }
792 
793 void
794 loop(struct tls *ctx, int sock)
795 {
796 	int i, todo;
797 	struct client clients[MAX_USERS];
798 	struct pollfd fds[MAX_USERS];
799 
800 	for (i = 0; i < MAX_USERS; ++i) {
801 		fds[i].fd = -1;
802 		fds[i].events = POLLIN;
803 		bzero(&clients[i], sizeof(struct client));
804 	}
805 
806 	fds[0].fd = sock;
807 
808 	for (;;) {
809 		if ((todo = poll(fds, MAX_USERS, INFTIM)) == -1) {
810 			if (errno == EINTR) {
811                                 warnx("connected clients: %d",
812 				    connected_clients);
813 				continue;
814 			}
815 			FATAL("poll: %s", strerror(errno));
816 		}
817 
818 		for (i = 0; i < MAX_USERS; i++) {
819 			assert(i < MAX_USERS);
820 
821 			if (fds[i].revents == 0)
822 				continue;
823 
824 			if (fds[i].revents & (POLLERR|POLLNVAL))
825 				FATAL("bad fd %d: %s", fds[i].fd,
826 				    strerror(errno));
827 
828 			if (fds[i].revents & POLLHUP) {
829 				/* fds[i] may be the fd of the stdin
830 				 * of a cgi script that has exited. */
831 				if (!clients[i].waiting_on_child) {
832 					goodbye(&fds[i], &clients[i]);
833 					continue;
834 				}
835 			}
836 
837 			todo--;
838 
839 			if (i == 0) { /* new client */
840 				do_accept(sock, ctx, fds, clients);
841 				continue;
842 			}
843 
844 			handle(&fds[i], &clients[i]);
845 		}
846 	}
847 }
848 
849 char *
850 absolutify_path(const char *path)
851 {
852 	char *wd, *r;
853 
854 	if (*path == '/')
855 		return strdup(path);
856 
857 	wd = getwd(NULL);
858 	if (asprintf(&r, "%s/%s", wd, path) == -1)
859 		err(1, "asprintf");
860 	free(wd);
861 	return r;
862 }
863 
864 void
865 usage(const char *me)
866 {
867 	fprintf(stderr,
868 	    "USAGE: %s [-h] [-c cert.pem] [-d docs] [-k key.pem] "
869 	    "[-l logfile] [-p port] [-x cgi-bin]\n",
870 	    me);
871 }
872 
873 int
874 main(int argc, char **argv)
875 {
876 	const char *cert = "cert.pem", *key = "key.pem";
877 	struct tls *ctx = NULL;
878 	struct tls_config *conf;
879 	int sock, ch;
880 
881 	signal(SIGPIPE, SIG_IGN);
882 	signal(SIGCHLD, SIG_IGN);
883 
884 #ifdef SIGINFO
885 	signal(SIGINFO, siginfo_handler);
886 #endif
887 	signal(SIGUSR2, siginfo_handler);
888 
889 	connected_clients = 0;
890 
891 	if ((dir = absolutify_path("docs")) == NULL)
892 		err(1, "absolutify_path");
893 
894 	cgi = NULL;
895 	port = 1965;
896 	foreground = 0;
897 
898 	while ((ch = getopt(argc, argv, "c:d:fhk:p:x:")) != -1) {
899 		switch (ch) {
900 		case 'c':
901 			cert = optarg;
902 			break;
903 
904 		case 'd':
905 			free((char*)dir);
906 			if ((dir = absolutify_path(optarg)) == NULL)
907 				err(1, "absolutify_path");
908 			break;
909 
910 		case 'f':
911 			foreground = 1;
912 			break;
913 
914 		case 'h':
915 			usage(*argv);
916 			return 0;
917 
918 		case 'k':
919 			key = optarg;
920 			break;
921 
922 		case 'p': {
923 			char *ep;
924 			long lval;
925 
926 			errno = 0;
927 			lval = strtol(optarg, &ep, 10);
928 			if (optarg[0] == '\0' || *ep != '\0')
929 				err(1, "not a number: %s", optarg);
930 			if (lval < 0 || lval > UINT16_MAX)
931 				err(1, "port number out of range: %s", optarg);
932 			port = lval;
933 			break;
934 		}
935 
936 		case 'x':
937 			cgi = optarg;
938 			break;
939 
940 		default:
941 			usage(*argv);
942 			return 1;
943 		}
944 	}
945 
946 	if ((conf = tls_config_new()) == NULL)
947 		err(1, "tls_config_new");
948 
949 	/* optionally accept client certs, but don't try to verify them */
950 	tls_config_verify_client_optional(conf);
951 	tls_config_insecure_noverifycert(conf);
952 
953 	if (tls_config_set_protocols(conf,
954 	    TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3) == -1)
955 		err(1, "tls_config_set_protocols");
956 
957 	if (tls_config_set_cert_file(conf, cert) == -1)
958 		err(1, "tls_config_set_cert_file: %s", cert);
959 
960 	if (tls_config_set_key_file(conf, key) == -1)
961 		err(1, "tls_config_set_key_file: %s", key);
962 
963 	if ((ctx = tls_server()) == NULL)
964 		err(1, "tls_server");
965 
966 	if (tls_configure(ctx, conf) == -1)
967 		errx(1, "tls_configure: %s", tls_error(ctx));
968 
969 	sock = make_socket(port, AF_INET);
970 
971 	if ((dirfd = open(dir, O_RDONLY | O_DIRECTORY)) == -1)
972 		err(1, "open: %s", dir);
973 
974 	if (!foreground && daemon(0, 1) == -1)
975 		exit(1);
976 
977 	if (cgi != NULL) {
978 		if (unveil(dir, "rx") == -1)
979 			err(1, "unveil");
980 		if (pledge("stdio rpath inet proc exec", NULL) == -1)
981 			err(1, "pledge");
982 	} else {
983 		if (unveil(dir, "r") == -1)
984 			err(1, "unveil");
985 		if (pledge("stdio rpath inet", NULL) == -1)
986 			err(1, "pledge");
987 	}
988 
989 	loop(ctx, sock);
990 
991 	close(sock);
992 	tls_free(ctx);
993 	tls_config_free(conf);
994 }