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Date:: Wed Nov 18 08:34:42 2020 UTC
Message:: correctly handle also non absolute URLs
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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 <arpa/inet.h>
22 #include <netinet/in.h>
23 
24 #include <assert.h>
25 #include <err.h>
26 #include <errno.h>
27 #include <fcntl.h>
28 #include <poll.h>
29 #include <signal.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <tls.h>
34 #include <unistd.h>
35 
36 #ifndef __OpenBSD__
37 # define pledge(a, b) 0
38 # define unveil(a, b) 0
39 #endif /* __OpenBSD__ */
40 
41 #ifndef INFTIM
42 # define INFTIM -1
43 #endif /* INFTIM */
44 
45 #define GEMINI_URL_LEN (1024+3)	/* URL max len + \r\n + \0 */
46 
47 /* large enough to hold a copy of a gemini URL and still have extra room */
48 #define PATHBUF		2048
49 
50 #define SUCCESS		20
51 #define TEMP_FAILURE	40
52 #define NOT_FOUND	51
53 #define BAD_REQUEST	59
54 
55 #ifndef MAX_USERS
56 #define MAX_USERS	64
57 #endif
58 
59 enum {
60 	S_OPEN,
61 	S_INITIALIZING,
62 	S_SENDING,
63 	S_CLOSING,
64 };
65 
66 struct client {
67 	struct tls	*ctx;
68 	int		 state;
69 	int		 code;
70 	const char	*meta;
71 	int		 fd, waiting_on_child;
72 	pid_t		 child;
73 	char		 sbuf[1024];	  /* static buffer */
74 	void		*buf, *i;	  /* mmap buffer */
75 	ssize_t		 len, off;	  /* mmap/static buffer  */
76 	int		 af;
77 	struct in_addr	 addr;
78 };
79 
80 enum {
81 	FILE_EXISTS,
82 	FILE_EXECUTABLE,
83 	FILE_DIRECTORY,
84 	FILE_MISSING,
85 };
86 
87 struct etm {			/* file extension to mime */
88 	const char	*mime;
89 	const char	*ext;
90 } filetypes[] = {
91 	{"application/pdf",	"pdf"},
92 
93 	{"image/gif",		"gif"},
94 	{"image/jpeg",		"jpg"},
95 	{"image/jpeg",		"jpeg"},
96 	{"image/png",		"png"},
97 	{"image/svg+xml",	"svg"},
98 
99 	{"text/gemini",		"gemini"},
100 	{"text/gemini",		"gmi"},
101 	{"text/markdown",	"markdown"},
102 	{"text/markdown",	"md"},
103 	{"text/plain",		"txt"},
104 	{"text/xml",		"xml"},
105 
106 	{NULL, NULL}
107 };
108 
109 #define LOG(c, fmt, ...)						\
110 	do {								\
111 		char buf[INET_ADDRSTRLEN];				\
112 		if (inet_ntop((c)->af, &(c)->addr, buf, sizeof(buf)) == NULL) \
113 			err(1, "inet_ntop");				\
114 		dprintf(logfd, "[%s] " fmt "\n", buf, __VA_ARGS__);	\
115 	} while (0)
116 
117 const char *dir, *cgi;
118 int dirfd, logfd;
119 int port;
120 int connected_clients;
121 
122 void		 siginfo_handler(int);
123 int		 starts_with(const char*, const char*);
124 
125 char		*url_after_proto(char*);
126 char		*url_start_of_request(char*);
127 int		 url_trim(struct client*, char*);
128 char		*adjust_path(char*);
129 ssize_t		 filesize(int);
130 
131 int		 start_reply(struct pollfd*, struct client*, int, const char*);
132 const char	*path_ext(const char*);
133 const char	*mime(const char*);
134 int		 check_path(const char*, int*);
135 int		 check_for_cgi(char *, char*, struct pollfd*, struct client*);
136 int		 open_file(char*, char*, struct pollfd*, struct client*);
137 int		 start_cgi(const char*, const char*, const char*, struct pollfd*, struct client*);
138 void		 cgi_setpoll_on_child(struct pollfd*, struct client*);
139 void		 cgi_setpoll_on_client(struct pollfd*, struct client*);
140 void		 handle_cgi(struct pollfd*, struct client*);
141 void		 send_file(char*, char*, struct pollfd*, struct client*);
142 void		 send_dir(char*, struct pollfd*, struct client*);
143 void		 handle(struct pollfd*, struct client*);
144 
145 void		 mark_nonblock(int);
146 int		 make_soket(int);
147 void		 do_accept(int, struct tls*, struct pollfd*, struct client*);
148 void		 goodbye(struct pollfd*, struct client*);
149 void		 loop(struct tls*, int);
150 
151 void		 usage(const char*);
152 
153 void
154 siginfo_handler(int sig)
155 {
156 	(void)sig;
157 }
158 
159 int
160 starts_with(const char *str, const char *prefix)
161 {
162 	size_t i;
163 
164 	for (i = 0; prefix[i] != '\0'; ++i)
165 		if (str[i] != prefix[i])
166 			return 0;
167 	return 1;
168 }
169 
170 char *
171 url_after_proto(char *url)
172 {
173 	char *s;
174 	const char *proto = "gemini";
175 	const char *marker = "//";
176 
177 	/* a relative URL */
178 	if ((s = strstr(url, marker)) == NULL)
179 		return url;
180 
181 	/*
182 	 * if a protocol is not specified, gemini should be implied:
183 	 * this handles the case of //example.com
184 	 */
185 	if (s == url)
186 		return s + strlen(marker);
187 
188 	if (s - strlen(proto) != url)
189 		return NULL;
190 
191 	if (!starts_with(url, proto))
192 		return NULL;
193 
194 	return s + strlen(marker);
195 }
196 
197 char *
198 url_start_of_request(char *url)
199 {
200 	char *s, *t;
201 
202 	if ((s = url_after_proto(url)) == NULL)
203 		return NULL;
204 
205 	/* non-absolute URL */
206 	if (s == url)
207 		return s;
208 
209 	if ((t = strstr(s, "/")) == NULL)
210 		return s + strlen(s);
211 	return t;
212 }
213 
214 int
215 url_trim(struct client *c, char *url)
216 {
217 	const char *e = "\r\n";
218 	char *s;
219 
220 	if ((s = strstr(url, e)) == NULL)
221 		return 0;
222 	s[0] = '\0';
223 	s[1] = '\0';
224 
225 	if (s[2] != '\0') {
226 		LOG(c, "%s", "request longer than 1024 bytes\n");
227 		return 0;
228 	}
229 
230 	return 1;
231 }
232 
233 char *
234 adjust_path(char *path)
235 {
236 	char *s, *query;
237 	size_t len;
238 
239 	if ((query = strchr(path, '?')) != NULL) {
240 		*query = '\0';
241 		query++;
242 	}
243 
244 	/* /.. -> / */
245 	len = strlen(path);
246 	if (len >= 3) {
247 		if (!strcmp(&path[len-3], "/..")) {
248 			path[len-2] = '\0';
249 		}
250 	}
251 
252 	/* if the path is only `..` trim out and exit */
253 	if (!strcmp(path, "..")) {
254 		path[0] = '\0';
255 		return query;
256 	}
257 
258 	/* remove every ../ in the path */
259 	while (1) {
260 		if ((s = strstr(path, "../")) == NULL)
261 			return query;
262 		memmove(s, s+3, strlen(s)+1);	/* copy also the \0 */
263 	}
264 }
265 
266 int
267 start_reply(struct pollfd *pfd, struct client *client, int code, const char *reason)
268 {
269 	char buf[1030] = {0}; 	/* status + ' ' + max reply len + \r\n\0 */
270 	int len;
271 	int ret;
272 
273 	client->code = code;
274 	client->meta = reason;
275 	client->state = S_INITIALIZING;
276 
277 	len = snprintf(buf, sizeof(buf), "%d %s\r\n", code, reason);
278 	assert(len < (int)sizeof(buf));
279 	ret = tls_write(client->ctx, buf, len);
280 	if (ret == TLS_WANT_POLLIN) {
281 		pfd->events = POLLIN;
282 		return 0;
283 	}
284 
285 	if (ret == TLS_WANT_POLLOUT) {
286 		pfd->events = POLLOUT;
287 		return 0;
288 	}
289 
290 	return 1;
291 }
292 
293 ssize_t
294 filesize(int fd)
295 {
296 	ssize_t len;
297 
298 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
299 		return -1;
300 	if (lseek(fd, 0, SEEK_SET) == -1)
301 		return -1;
302 	return len;
303 }
304 
305 const char *
306 path_ext(const char *path)
307 {
308 	const char *end;
309 
310 	end = path + strlen(path)-1; /* the last byte before the NUL */
311 	for (; end != path; --end) {
312 		if (*end == '.')
313 			return end+1;
314 		if (*end == '/')
315 			break;
316 	}
317 
318 	return NULL;
319 }
320 
321 const char *
322 mime(const char *path)
323 {
324 	const char *ext, *def = "application/octet-stream";
325 	struct etm *t;
326 
327 	if ((ext = path_ext(path)) == NULL)
328 		return def;
329 
330 	for (t = filetypes; t->mime != NULL; ++t)
331 		if (!strcmp(ext, t->ext))
332 			return t->mime;
333 
334 	return def;
335 }
336 
337 int
338 check_path(const char *path, int *fd)
339 {
340 	struct stat sb;
341 
342 	assert(path != NULL);
343 	if ((*fd = openat(dirfd, path,
344 		    O_RDONLY | O_NOFOLLOW | O_CLOEXEC)) == -1) {
345 		return FILE_MISSING;
346 	}
347 
348 	if (fstat(*fd, &sb) == -1) {
349 		dprintf(logfd, "failed stat for %s\n", path);
350 		return FILE_MISSING;
351 	}
352 
353 	if (S_ISDIR(sb.st_mode))
354 		return FILE_DIRECTORY;
355 
356 	if (sb.st_mode & S_IXUSR)
357 		return FILE_EXECUTABLE;
358 
359 	return FILE_EXISTS;
360 }
361 
362 /*
363  * the inverse of this algorithm, i.e. starting from the start of the
364  * path + strlen(cgi), and checking if each component, should be
365  * faster.  But it's tedious to write.  This does the opposite: starts
366  * from the end and strip one component at a time, until either an
367  * executable is found or we emptied the path.
368  */
369 int
370 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
371 {
372 	char *end;
373 	end = strchr(path, '\0');
374 
375 	/* NB: assume CGI is enabled and path matches cgi */
376 
377 	while (end > path) {
378 		/* go up one level.  UNIX paths are simple and POSIX
379 		 * dirname, with its ambiguities on if the given path
380 		 * is changed or not, gives me headaches. */
381 		while (*end != '/')
382 			end--;
383 		*end = '\0';
384 
385 		switch (check_path(path, &c->fd)) {
386 		case FILE_EXECUTABLE:
387 			return start_cgi(path, end+1, query, fds,c);
388 		case FILE_MISSING:
389 			break;
390 		default:
391 			goto err;
392 		}
393 
394 		*end = '/';
395 		end--;
396 	}
397 
398 err:
399 	if (!start_reply(fds, c, NOT_FOUND, "not found"))
400 		return 0;
401 	goodbye(fds, c);
402 	return 0;
403 }
404 
405 
406 int
407 open_file(char *path, char *query, struct pollfd *fds, struct client *c)
408 {
409 	char fpath[PATHBUF];
410 
411 	bzero(fpath, sizeof(fpath));
412 
413 	if (*path != '.')
414 		fpath[0] = '.';
415 	strlcat(fpath, path, PATHBUF);
416 
417 	switch (check_path(fpath, &c->fd)) {
418 	case FILE_EXECUTABLE:
419 		/* +2 to skip the ./ */
420 		if (cgi != NULL && starts_with(fpath+2, cgi))
421 			return start_cgi(fpath, "", query, fds, c);
422 
423 		/* fallthrough */
424 
425 	case FILE_EXISTS:
426 		if ((c->len = filesize(c->fd)) == -1) {
427 			LOG(c, "failed to get file size for %s", fpath);
428 			goodbye(fds, c);
429 			return 0;
430 		}
431 
432 		if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
433 			    c->fd, 0)) == MAP_FAILED) {
434 			warn("mmap: %s", fpath);
435 			goodbye(fds, c);
436 			return 0;
437 		}
438 		c->i = c->buf;
439 		return start_reply(fds, c, SUCCESS, mime(fpath));
440 
441 	case FILE_DIRECTORY:
442 		LOG(c, "%s is a directory, trying %s/index.gmi", fpath, fpath);
443 		close(c->fd);
444 		c->fd = -1;
445 		send_dir(fpath, fds, c);
446 		return 0;
447 
448 	case FILE_MISSING:
449 		if (cgi != NULL && starts_with(fpath+2, cgi))
450 			return check_for_cgi(fpath, query, fds, c);
451 
452 		if (!start_reply(fds, c, NOT_FOUND, "not found"))
453 			return 0;
454 		goodbye(fds, c);
455 		return 0;
456 
457 	default:
458 		/* unreachable */
459 		abort();
460 	}
461 }
462 
463 int
464 start_cgi(const char *spath, const char *relpath, const char *query,
465     struct pollfd *fds, struct client *c)
466 {
467 	pid_t pid;
468 	int p[2]; 		/* read end, write end */
469 
470 	if (pipe(p) == -1)
471 		goto err;
472 
473 	switch (pid = fork()) {
474 	case -1:
475 		goto err;
476 
477 	case 0: { 		/* child */
478 		char *ex, *requri, *portno;
479 		char addr[INET_ADDRSTRLEN];
480 		char *argv[] = { NULL, NULL, NULL };
481 
482 		spath++;
483 
484 		close(p[0]);
485 		if (dup2(p[1], 1) == -1)
486 			goto childerr;
487 
488 		if (inet_ntop(c->af, &c->addr, addr, sizeof(addr)) == NULL)
489 			goto childerr;
490 
491 		if (asprintf(&portno, "%d", port) == -1)
492 			goto childerr;
493 
494 		if (asprintf(&ex, "%s%s", dir, spath+1) == -1)
495 			goto childerr;
496 
497 		if (asprintf(&requri, "%s%s%s", spath,
498 		    *relpath == '\0' ? "" : "/",
499 		    relpath) == -1)
500 			goto childerr;
501 
502 		argv[0] = argv[1] = ex;
503 
504 		/* fix the env */
505 		setenv("SERVER_SOFTWARE", "gmid", 1);
506 		setenv("SERVER_PORT", portno, 1);
507 		/* setenv("SERVER_NAME", "", 1); */
508 		setenv("SCRIPT_NAME", spath, 1);
509 		setenv("SCRIPT_EXECUTABLE", ex, 1);
510 		setenv("REQUEST_URI", requri, 1);
511 		setenv("REQUEST_RELATIVE", relpath, 1);
512 		if (query != NULL)
513 			setenv("QUERY_STRING", query, 1);
514 		setenv("REMOTE_HOST", addr, 1);
515 		setenv("DOCUMENT_ROOT", dir, 1);
516 
517 		execvp(ex, argv);
518 		goto childerr;
519 	}
520 
521 	default:		/* parent */
522 		close(p[1]);
523 		close(c->fd);
524 		c->fd = p[0];
525 		c->child = pid;
526 		mark_nonblock(c->fd);
527 		c->state = S_SENDING;
528 		handle_cgi(fds, c);
529 		return 0;
530 	}
531 
532 err:
533 	if (!start_reply(fds, c, TEMP_FAILURE, "internal server error"))
534 		return 0;
535 	goodbye(fds, c);
536 	return 0;
537 
538 childerr:
539 	dprintf(p[1], "%d internal server error\r\n", TEMP_FAILURE);
540 	close(p[1]);
541 	_exit(1);
542 }
543 
544 void
545 cgi_setpoll_on_child(struct pollfd *fds, struct client *c)
546 {
547 	int fd;
548 
549 	if (c->waiting_on_child)
550 		return;
551 	c->waiting_on_child = 1;
552 
553 	fds->events = POLLIN;
554 
555 	fd = fds->fd;
556 	fds->fd = c->fd;
557 	c->fd = fd;
558 }
559 
560 void
561 cgi_setpoll_on_client(struct pollfd *fds, struct client *c)
562 {
563 	int fd;
564 
565 	if (!c->waiting_on_child)
566 		return;
567 	c->waiting_on_child = 0;
568 
569 	fd = fds->fd;
570 	fds->fd = c->fd;
571 	c->fd = fd;
572 }
573 
574 void
575 handle_cgi(struct pollfd *fds, struct client *c)
576 {
577 	ssize_t r;
578 
579 	/* ensure c->fd is the child and fds->fd the client */
580 	cgi_setpoll_on_client(fds, c);
581 
582 	while (1) {
583 		if (c->len == 0) {
584 			if ((r = read(c->fd, c->sbuf, sizeof(c->sbuf))) == 0)
585 				goto end;
586 			if (r == -1) {
587 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
588 					cgi_setpoll_on_child(fds, c);
589 					return;
590 				}
591                                 goto end;
592 			}
593 			c->len = r;
594 			c->off = 0;
595 		}
596 
597 		while (c->len > 0) {
598 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
599 			case -1:
600 				goto end;
601 
602 			case TLS_WANT_POLLOUT:
603 				fds->events = POLLOUT;
604 				return;
605 
606 			case TLS_WANT_POLLIN:
607 				fds->events = POLLIN;
608 				return;
609 
610 			default:
611                                 c->off += r;
612 				c->len -= r;
613 				break;
614 			}
615 		}
616 	}
617 
618 end:
619 	goodbye(fds, c);
620 }
621 
622 void
623 send_file(char *path, char *query, struct pollfd *fds, struct client *c)
624 {
625 	ssize_t ret, len;
626 
627 	if (c->fd == -1) {
628 		if (!open_file(path, query, fds, c))
629 			return;
630 		c->state = S_SENDING;
631 	}
632 
633 	len = (c->buf + c->len) - c->i;
634 
635 	while (len > 0) {
636 		switch (ret = tls_write(c->ctx, c->i, len)) {
637 		case -1:
638 			LOG(c, "tls_write: %s", tls_error(c->ctx));
639 			goodbye(fds, c);
640 			return;
641 
642 		case TLS_WANT_POLLIN:
643 			fds->events = POLLIN;
644 			return;
645 
646 		case TLS_WANT_POLLOUT:
647 			fds->events = POLLOUT;
648 			return;
649 
650 		default:
651 			c->i += ret;
652 			len -= ret;
653 			break;
654 		}
655 	}
656 
657 	goodbye(fds, c);
658 }
659 
660 void
661 send_dir(char *path, struct pollfd *fds, struct client *client)
662 {
663 	char fpath[PATHBUF];
664 	size_t len;
665 
666 	bzero(fpath, PATHBUF);
667 
668 	if (path[0] != '.')
669 		fpath[0] = '.';
670 
671 	/* this cannot fail since sizeof(fpath) > maxlen of path */
672 	strlcat(fpath, path, PATHBUF);
673 	len = strlen(fpath);
674 
675 	/* add a trailing / in case. */
676 	if (fpath[len-1] != '/') {
677 		fpath[len] = '/';
678 	}
679 
680 	strlcat(fpath, "index.gmi", sizeof(fpath));
681 
682 	send_file(fpath, NULL, fds, client);
683 }
684 
685 void
686 handle(struct pollfd *fds, struct client *client)
687 {
688 	char buf[GEMINI_URL_LEN];
689 	char *path;
690 	char *query;
691 
692 	switch (client->state) {
693 	case S_OPEN:
694 		bzero(buf, GEMINI_URL_LEN);
695 		switch (tls_read(client->ctx, buf, sizeof(buf)-1)) {
696 		case -1:
697 			LOG(client, "tls_read: %s", tls_error(client->ctx));
698 			goodbye(fds, client);
699 			return;
700 
701 		case TLS_WANT_POLLIN:
702 			fds->events = POLLIN;
703 			return;
704 
705 		case TLS_WANT_POLLOUT:
706 			fds->events = POLLOUT;
707 			return;
708 		}
709 
710 		if (!url_trim(client, buf)) {
711 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
712 				return;
713 			goodbye(fds, client);
714 			return;
715 		}
716 
717 		if ((path = url_start_of_request(buf)) == NULL) {
718 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
719 				return;
720 			goodbye(fds, client);
721 			return;
722 		}
723 
724 		query = adjust_path(path);
725 		LOG(client, "get %s%s%s", path,
726 		    query ? "?" : "",
727 		    query ? query : "");
728 
729 		send_file(path, query, fds, client);
730 		break;
731 
732 	case S_INITIALIZING:
733 		if (!start_reply(fds, client, client->code, client->meta))
734 			return;
735 
736 		if (client->code != SUCCESS) {
737 			/* we don't need a body */
738 			goodbye(fds, client);
739 			return;
740 		}
741 
742 		client->state = S_SENDING;
743 
744 		/* fallthrough */
745 
746 	case S_SENDING:
747 		if (client->child != -1)
748 			handle_cgi(fds, client);
749 		else
750 			send_file(NULL, NULL, fds, client);
751 		break;
752 
753 	case S_CLOSING:
754 		goodbye(fds, client);
755 		break;
756 
757 	default:
758 		/* unreachable */
759 		abort();
760 	}
761 }
762 
763 void
764 mark_nonblock(int fd)
765 {
766 	int flags;
767 
768 	if ((flags = fcntl(fd, F_GETFL)) == -1)
769 		err(1, "fcntl(F_GETFL)");
770 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
771 		err(1, "fcntl(F_SETFL)");
772 }
773 
774 int
775 make_socket(int port, int family)
776 {
777 	int sock, v;
778 	struct sockaddr_in addr4;
779 	struct sockaddr_in6 addr6;
780 	struct sockaddr *addr;
781 	socklen_t len;
782 
783         switch (family) {
784 	case AF_INET:
785 		bzero(&addr4, sizeof(addr4));
786 		addr4.sin_family = family;
787 		addr4.sin_port = htons(port);
788 		addr4.sin_addr.s_addr = INADDR_ANY;
789 		addr = (struct sockaddr*)&addr4;
790 		len = sizeof(addr4);
791 		break;
792 
793 	case AF_INET6:
794 		bzero(&addr6, sizeof(addr6));
795 		addr6.sin6_family = AF_INET6;
796 		addr6.sin6_port = htons(port);
797 		addr6.sin6_addr = in6addr_any;
798 		addr = (struct sockaddr*)&addr6;
799 		len = sizeof(addr6);
800 		break;
801 
802 	default:
803 		/* unreachable */
804 		abort();
805 	}
806 
807 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
808 		err(1, "socket");
809 
810 	v = 1;
811 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
812 		err(1, "setsockopt(SO_REUSEADDR)");
813 
814 	v = 1;
815 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
816 		err(1, "setsockopt(SO_REUSEPORT)");
817 
818 	mark_nonblock(sock);
819 
820 	if (bind(sock, addr, len) == -1)
821 		err(1, "bind");
822 
823 	if (listen(sock, 16) == -1)
824 		err(1, "listen");
825 
826 	return sock;
827 }
828 
829 void
830 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
831 {
832 	int i, fd;
833 	struct sockaddr_in addr;
834 	socklen_t len;
835 
836 	len = sizeof(addr);
837 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
838 		if (errno == EWOULDBLOCK)
839 			return;
840 		err(1, "accept");
841 	}
842 
843 	mark_nonblock(fd);
844 
845 	for (i = 0; i < MAX_USERS; ++i) {
846 		if (fds[i].fd == -1) {
847 			bzero(&clients[i], sizeof(struct client));
848 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
849 				break; /* goodbye fd! */
850 
851 			fds[i].fd = fd;
852 			fds[i].events = POLLIN;
853 
854 			clients[i].state = S_OPEN;
855 			clients[i].fd = -1;
856 			clients[i].child = -1;
857 			clients[i].buf = MAP_FAILED;
858 			clients[i].af = AF_INET;
859 			clients[i].addr = addr.sin_addr;
860 
861 			connected_clients++;
862 			return;
863 		}
864 	}
865 
866 	close(fd);
867 }
868 
869 void
870 goodbye(struct pollfd *pfd, struct client *c)
871 {
872 	ssize_t ret;
873 
874 	c->state = S_CLOSING;
875 
876 	ret = tls_close(c->ctx);
877 	if (ret == TLS_WANT_POLLIN) {
878 		pfd->events = POLLIN;
879 		return;
880 	}
881 	if (ret == TLS_WANT_POLLOUT) {
882 		pfd->events = POLLOUT;
883 		return;
884 	}
885 
886 	connected_clients--;
887 
888 	tls_free(c->ctx);
889 	c->ctx = NULL;
890 
891 	if (c->buf != MAP_FAILED)
892 		munmap(c->buf, c->len);
893 
894 	if (c->fd != -1)
895 		close(c->fd);
896 
897 	close(pfd->fd);
898 	pfd->fd = -1;
899 }
900 
901 void
902 loop(struct tls *ctx, int sock)
903 {
904 	int i, todo;
905 	struct client clients[MAX_USERS];
906 	struct pollfd fds[MAX_USERS];
907 
908 	for (i = 0; i < MAX_USERS; ++i) {
909 		fds[i].fd = -1;
910 		fds[i].events = POLLIN;
911 		bzero(&clients[i], sizeof(struct client));
912 	}
913 
914 	fds[0].fd = sock;
915 
916 	for (;;) {
917 		if ((todo = poll(fds, MAX_USERS, INFTIM)) == -1) {
918 			if (errno == EINTR) {
919                                 warnx("connected clients: %d", connected_clients);
920 				continue;
921 			}
922 			err(1, "poll");
923 		}
924 
925 		for (i = 0; i < MAX_USERS; i++) {
926 			assert(i < MAX_USERS);
927 
928 			if (fds[i].revents == 0)
929 				continue;
930 
931 			if (fds[i].revents & (POLLERR|POLLNVAL))
932 				err(1, "bad fd %d", fds[i].fd);
933 
934 			if (fds[i].revents & POLLHUP) {
935 				/* fds[i] may be the fd of the stdin
936 				 * of a cgi script that has exited. */
937 				if (!clients[i].waiting_on_child) {
938 					goodbye(&fds[i], &clients[i]);
939 					continue;
940 				}
941 			}
942 
943 			todo--;
944 
945 			if (i == 0) { /* new client */
946 				do_accept(sock, ctx, fds, clients);
947 				continue;
948 			}
949 
950 			handle(&fds[i], &clients[i]);
951 		}
952 	}
953 }
954 
955 void
956 usage(const char *me)
957 {
958 	fprintf(stderr,
959 	    "USAGE: %s [-h] [-c cert.pem] [-d docs] [-k key.pem] "
960 	    "[-l logfile] [-p port] [-x cgi-bin]\n",
961 	    me);
962 }
963 
964 int
965 main(int argc, char **argv)
966 {
967 	const char *cert = "cert.pem", *key = "key.pem";
968 	struct tls *ctx = NULL;
969 	struct tls_config *conf;
970 	int sock, ch;
971 
972 	signal(SIGPIPE, SIG_IGN);
973 	signal(SIGCHLD, SIG_IGN);
974 
975 #ifdef SIGINFO
976 	signal(SIGINFO, siginfo_handler);
977 #endif
978 	signal(SIGUSR2, siginfo_handler);
979 
980 	connected_clients = 0;
981 
982 	dir = "docs/";
983 	logfd = 2;		/* stderr */
984 	cgi = NULL;
985 	port = 1965;
986 
987 	while ((ch = getopt(argc, argv, "c:d:hk:l:p:x:")) != -1) {
988 		switch (ch) {
989 		case 'c':
990 			cert = optarg;
991 			break;
992 
993 		case 'd':
994 			dir = optarg;
995 			break;
996 
997 		case 'h':
998 			usage(*argv);
999 			return 0;
1000 
1001 		case 'k':
1002 			key = optarg;
1003 			break;
1004 
1005 		case 'l':
1006 			/* open log file or create it with 644 */
1007 			if ((logfd = open(optarg, O_WRONLY | O_CREAT | O_CLOEXEC,
1008 					S_IRUSR | S_IWUSR | S_IRGRP | S_IWOTH)) == -1)
1009 				err(1, "%s", optarg);
1010 			break;
1011 
1012 		case 'p': {
1013 			char *ep;
1014 			long lval;
1015 
1016 			errno = 0;
1017 			lval = strtol(optarg, &ep, 10);
1018 			if (optarg[0] == '\0' || *ep != '\0')
1019 				err(1, "not a number: %s", optarg);
1020 			if (lval < 0 || lval > UINT16_MAX)
1021 				err(1, "port number out of range: %s", optarg);
1022 			port = lval;
1023 			break;
1024 		}
1025 
1026 		case 'x':
1027 			cgi = optarg;
1028 			break;
1029 
1030 		default:
1031 			usage(*argv);
1032 			return 1;
1033 		}
1034 	}
1035 
1036 	if ((conf = tls_config_new()) == NULL)
1037 		err(1, "tls_config_new");
1038 
1039 	if (tls_config_set_protocols(conf,
1040 	    TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3) == -1)
1041 		err(1, "tls_config_set_protocols");
1042 
1043 	if (tls_config_set_cert_file(conf, cert) == -1)
1044 		err(1, "tls_config_set_cert_file: %s", cert);
1045 
1046 	if (tls_config_set_key_file(conf, key) == -1)
1047 		err(1, "tls_config_set_key_file: %s", key);
1048 
1049 	if ((ctx = tls_server()) == NULL)
1050 		err(1, "tls_server");
1051 
1052 	if (tls_configure(ctx, conf) == -1)
1053 		errx(1, "tls_configure: %s", tls_error(ctx));
1054 
1055 	sock = make_socket(port, AF_INET);
1056 
1057 	if ((dirfd = open(dir, O_RDONLY | O_DIRECTORY)) == -1)
1058 		err(1, "open: %s", dir);
1059 
1060 	if (cgi != NULL) {
1061 		if (unveil(dir, "rx") == -1)
1062 			err(1, "unveil");
1063 		if (pledge("stdio rpath inet proc exec", NULL) == -1)
1064 			err(1, "pledge");
1065 	} else {
1066 		if (unveil(dir, "r") == -1)
1067 			err(1, "unveil");
1068 		if (pledge("stdio rpath inet", NULL) == -1)
1069 			err(1, "pledge");
1070 	}
1071 
1072 	loop(ctx, sock);
1073 
1074 	close(sock);
1075 	tls_free(ctx);
1076 	tls_config_free(conf);
1077 }