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 #define SAFE_SETENV(var, val) do {		\
60 		const char *_tmp = (val);	\
61 		if (_tmp == NULL)		\
62 			_tmp = "";		\
63 		setenv((var), _tmp, 1);		\
64 	} while(0)
65 
66 enum {
67 	S_OPEN,
68 	S_INITIALIZING,
69 	S_SENDING,
70 	S_CLOSING,
71 };
72 
73 struct client {
74 	struct tls	*ctx;
75 	int		 state;
76 	int		 code;
77 	const char	*meta;
78 	int		 fd, waiting_on_child;
79 	pid_t		 child;
80 	char		 sbuf[1024];	  /* static buffer */
81 	void		*buf, *i;	  /* mmap buffer */
82 	ssize_t		 len, off;	  /* mmap/static buffer  */
83 	int		 af;
84 	struct in_addr	 addr;
85 };
86 
87 enum {
88 	FILE_EXISTS,
89 	FILE_EXECUTABLE,
90 	FILE_DIRECTORY,
91 	FILE_MISSING,
92 };
93 
94 struct etm {			/* file extension to mime */
95 	const char	*mime;
96 	const char	*ext;
97 } filetypes[] = {
98 	{"application/pdf",	"pdf"},
99 
100 	{"image/gif",		"gif"},
101 	{"image/jpeg",		"jpg"},
102 	{"image/jpeg",		"jpeg"},
103 	{"image/png",		"png"},
104 	{"image/svg+xml",	"svg"},
105 
106 	{"text/gemini",		"gemini"},
107 	{"text/gemini",		"gmi"},
108 	{"text/markdown",	"markdown"},
109 	{"text/markdown",	"md"},
110 	{"text/plain",		"txt"},
111 	{"text/xml",		"xml"},
112 
113 	{NULL, NULL}
114 };
115 
116 #define LOG(c, fmt, ...)						\
117 	do {								\
118 		char buf[INET_ADDRSTRLEN];				\
119 		if (inet_ntop((c)->af, &(c)->addr, buf, sizeof(buf)) == NULL) \
120 			err(1, "inet_ntop");				\
121 		dprintf(logfd, "[%s] " fmt "\n", buf, __VA_ARGS__);	\
122 	} while (0)
123 
124 const char *dir, *cgi;
125 int dirfd, logfd;
126 int port;
127 int connected_clients;
128 
129 void		 siginfo_handler(int);
130 int		 starts_with(const char*, const char*);
131 
132 char		*url_after_proto(char*);
133 char		*url_start_of_request(char*);
134 int		 url_trim(struct client*, char*);
135 char		*adjust_path(char*);
136 ssize_t		 filesize(int);
137 
138 int		 start_reply(struct pollfd*, struct client*, int, const char*);
139 const char	*path_ext(const char*);
140 const char	*mime(const char*);
141 int		 check_path(const char*, int*);
142 int		 check_for_cgi(char *, char*, struct pollfd*, struct client*);
143 int		 open_file(char*, char*, struct pollfd*, struct client*);
144 int		 start_cgi(const char*, const char*, const char*, struct pollfd*, struct client*);
145 void		 cgi_setpoll_on_child(struct pollfd*, struct client*);
146 void		 cgi_setpoll_on_client(struct pollfd*, struct client*);
147 void		 handle_cgi(struct pollfd*, struct client*);
148 void		 send_file(char*, char*, struct pollfd*, struct client*);
149 void		 send_dir(char*, struct pollfd*, struct client*);
150 void		 handle(struct pollfd*, struct client*);
151 
152 void		 mark_nonblock(int);
153 int		 make_soket(int);
154 void		 do_accept(int, struct tls*, struct pollfd*, struct client*);
155 void		 goodbye(struct pollfd*, struct client*);
156 void		 loop(struct tls*, int);
157 
158 void		 usage(const char*);
159 
160 void
161 siginfo_handler(int sig)
162 {
163 	(void)sig;
164 }
165 
166 int
167 starts_with(const char *str, const char *prefix)
168 {
169 	size_t i;
170 
171 	for (i = 0; prefix[i] != '\0'; ++i)
172 		if (str[i] != prefix[i])
173 			return 0;
174 	return 1;
175 }
176 
177 char *
178 url_after_proto(char *url)
179 {
180 	char *s;
181 	const char *proto = "gemini:";
182 	const char *marker = "//";
183 
184 	/* a relative URL */
185 	if ((s = strstr(url, marker)) == NULL)
186 		return url;
187 
188 	/*
189 	 * if a protocol is not specified, gemini should be implied:
190 	 * this handles the case of //example.com
191 	 */
192 	if (s == url)
193 		return s + strlen(marker);
194 
195 	if (s - strlen(proto) != url)
196 		return NULL;
197 
198 	if (!starts_with(url, proto))
199 		return NULL;
200 
201 	return s + strlen(marker);
202 }
203 
204 char *
205 url_start_of_request(char *url)
206 {
207 	char *s, *t;
208 
209 	if ((s = url_after_proto(url)) == NULL)
210 		return NULL;
211 
212 	/* non-absolute URL */
213 	if (s == url)
214 		return s;
215 
216 	if ((t = strstr(s, "/")) == NULL)
217 		return s + strlen(s);
218 	return t;
219 }
220 
221 int
222 url_trim(struct client *c, char *url)
223 {
224 	const char *e = "\r\n";
225 	char *s;
226 
227 	if ((s = strstr(url, e)) == NULL)
228 		return 0;
229 	s[0] = '\0';
230 	s[1] = '\0';
231 
232 	if (s[2] != '\0') {
233 		LOG(c, "%s", "request longer than 1024 bytes\n");
234 		return 0;
235 	}
236 
237 	return 1;
238 }
239 
240 char *
241 adjust_path(char *path)
242 {
243 	char *s, *query;
244 	size_t len;
245 
246 	if ((query = strchr(path, '?')) != NULL) {
247 		*query = '\0';
248 		query++;
249 	}
250 
251 	/* /.. -> / */
252 	len = strlen(path);
253 	if (len >= 3) {
254 		if (!strcmp(&path[len-3], "/..")) {
255 			path[len-2] = '\0';
256 		}
257 	}
258 
259 	/* if the path is only `..` trim out and exit */
260 	if (!strcmp(path, "..")) {
261 		path[0] = '\0';
262 		return query;
263 	}
264 
265 	/* remove every ../ in the path */
266 	while (1) {
267 		if ((s = strstr(path, "../")) == NULL)
268 			return query;
269 		memmove(s, s+3, strlen(s)+1);	/* copy also the \0 */
270 	}
271 }
272 
273 int
274 start_reply(struct pollfd *pfd, struct client *client, int code, const char *reason)
275 {
276 	char buf[1030] = {0}; 	/* status + ' ' + max reply len + \r\n\0 */
277 	int len;
278 	int ret;
279 
280 	client->code = code;
281 	client->meta = reason;
282 	client->state = S_INITIALIZING;
283 
284 	len = snprintf(buf, sizeof(buf), "%d %s\r\n", code, reason);
285 	assert(len < (int)sizeof(buf));
286 	ret = tls_write(client->ctx, buf, len);
287 	if (ret == TLS_WANT_POLLIN) {
288 		pfd->events = POLLIN;
289 		return 0;
290 	}
291 
292 	if (ret == TLS_WANT_POLLOUT) {
293 		pfd->events = POLLOUT;
294 		return 0;
295 	}
296 
297 	return 1;
298 }
299 
300 ssize_t
301 filesize(int fd)
302 {
303 	ssize_t len;
304 
305 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
306 		return -1;
307 	if (lseek(fd, 0, SEEK_SET) == -1)
308 		return -1;
309 	return len;
310 }
311 
312 const char *
313 path_ext(const char *path)
314 {
315 	const char *end;
316 
317 	end = path + strlen(path)-1; /* the last byte before the NUL */
318 	for (; end != path; --end) {
319 		if (*end == '.')
320 			return end+1;
321 		if (*end == '/')
322 			break;
323 	}
324 
325 	return NULL;
326 }
327 
328 const char *
329 mime(const char *path)
330 {
331 	const char *ext, *def = "application/octet-stream";
332 	struct etm *t;
333 
334 	if ((ext = path_ext(path)) == NULL)
335 		return def;
336 
337 	for (t = filetypes; t->mime != NULL; ++t)
338 		if (!strcmp(ext, t->ext))
339 			return t->mime;
340 
341 	return def;
342 }
343 
344 int
345 check_path(const char *path, int *fd)
346 {
347 	struct stat sb;
348 
349 	assert(path != NULL);
350 	if ((*fd = openat(dirfd, path,
351 		    O_RDONLY | O_NOFOLLOW | O_CLOEXEC)) == -1) {
352 		return FILE_MISSING;
353 	}
354 
355 	if (fstat(*fd, &sb) == -1) {
356 		dprintf(logfd, "failed stat for %s\n", path);
357 		return FILE_MISSING;
358 	}
359 
360 	if (S_ISDIR(sb.st_mode))
361 		return FILE_DIRECTORY;
362 
363 	if (sb.st_mode & S_IXUSR)
364 		return FILE_EXECUTABLE;
365 
366 	return FILE_EXISTS;
367 }
368 
369 /*
370  * the inverse of this algorithm, i.e. starting from the start of the
371  * path + strlen(cgi), and checking if each component, should be
372  * faster.  But it's tedious to write.  This does the opposite: starts
373  * from the end and strip one component at a time, until either an
374  * executable is found or we emptied the path.
375  */
376 int
377 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
378 {
379 	char *end;
380 	end = strchr(path, '\0');
381 
382 	/* NB: assume CGI is enabled and path matches cgi */
383 
384 	while (end > path) {
385 		/* go up one level.  UNIX paths are simple and POSIX
386 		 * dirname, with its ambiguities on if the given path
387 		 * is changed or not, gives me headaches. */
388 		while (*end != '/')
389 			end--;
390 		*end = '\0';
391 
392 		switch (check_path(path, &c->fd)) {
393 		case FILE_EXECUTABLE:
394 			return start_cgi(path, end+1, query, fds,c);
395 		case FILE_MISSING:
396 			break;
397 		default:
398 			goto err;
399 		}
400 
401 		*end = '/';
402 		end--;
403 	}
404 
405 err:
406 	if (!start_reply(fds, c, NOT_FOUND, "not found"))
407 		return 0;
408 	goodbye(fds, c);
409 	return 0;
410 }
411 
412 
413 int
414 open_file(char *path, char *query, struct pollfd *fds, struct client *c)
415 {
416 	char fpath[PATHBUF];
417 
418 	bzero(fpath, sizeof(fpath));
419 
420 	if (*path != '.')
421 		fpath[0] = '.';
422 	strlcat(fpath, path, PATHBUF);
423 
424 	switch (check_path(fpath, &c->fd)) {
425 	case FILE_EXECUTABLE:
426 		/* +2 to skip the ./ */
427 		if (cgi != NULL && starts_with(fpath+2, cgi))
428 			return start_cgi(fpath, "", query, fds, c);
429 
430 		/* fallthrough */
431 
432 	case FILE_EXISTS:
433 		if ((c->len = filesize(c->fd)) == -1) {
434 			LOG(c, "failed to get file size for %s", fpath);
435 			goodbye(fds, c);
436 			return 0;
437 		}
438 
439 		if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
440 			    c->fd, 0)) == MAP_FAILED) {
441 			warn("mmap: %s", fpath);
442 			goodbye(fds, c);
443 			return 0;
444 		}
445 		c->i = c->buf;
446 		return start_reply(fds, c, SUCCESS, mime(fpath));
447 
448 	case FILE_DIRECTORY:
449 		LOG(c, "%s is a directory, trying %s/index.gmi", fpath, fpath);
450 		close(c->fd);
451 		c->fd = -1;
452 		send_dir(fpath, fds, c);
453 		return 0;
454 
455 	case FILE_MISSING:
456 		if (cgi != NULL && starts_with(fpath+2, cgi))
457 			return check_for_cgi(fpath, query, fds, c);
458 
459 		if (!start_reply(fds, c, NOT_FOUND, "not found"))
460 			return 0;
461 		goodbye(fds, c);
462 		return 0;
463 
464 	default:
465 		/* unreachable */
466 		abort();
467 	}
468 }
469 
470 int
471 start_cgi(const char *spath, const char *relpath, const char *query,
472     struct pollfd *fds, struct client *c)
473 {
474 	pid_t pid;
475 	int p[2]; 		/* read end, write end */
476 
477 	if (pipe(p) == -1)
478 		goto err;
479 
480 	switch (pid = fork()) {
481 	case -1:
482 		goto err;
483 
484 	case 0: { 		/* child */
485 		char *ex, *requri, *portno;
486 		char addr[INET_ADDRSTRLEN];
487 		char *argv[] = { NULL, NULL, NULL };
488 
489 		spath++;
490 
491 		close(p[0]);
492 		if (dup2(p[1], 1) == -1)
493 			goto childerr;
494 
495 		if (inet_ntop(c->af, &c->addr, addr, sizeof(addr)) == NULL)
496 			goto childerr;
497 
498 		if (asprintf(&portno, "%d", port) == -1)
499 			goto childerr;
500 
501 		if (asprintf(&ex, "%s%s", dir, spath+1) == -1)
502 			goto childerr;
503 
504 		if (asprintf(&requri, "%s%s%s", spath,
505 		    *relpath == '\0' ? "" : "/",
506 		    relpath) == -1)
507 			goto childerr;
508 
509 		argv[0] = argv[1] = ex;
510 
511 		/* fix the env */
512 		SAFE_SETENV("GATEWAY_INTERFACE", "CGI/1.1");
513 		SAFE_SETENV("SERVER_SOFTWARE", "gmid");
514 		SAFE_SETENV("SERVER_PORT", portno);
515 		/* setenv("SERVER_NAME", "", 1); */
516 		SAFE_SETENV("SCRIPT_NAME", spath);
517 		SAFE_SETENV("SCRIPT_EXECUTABLE", ex);
518 		SAFE_SETENV("REQUEST_URI", requri);
519 		SAFE_SETENV("REQUEST_RELATIVE", relpath);
520 		SAFE_SETENV("QUERY_STRING", query);
521 		SAFE_SETENV("REMOTE_HOST", addr);
522 		SAFE_SETENV("REMOTE_ADDR", addr);
523 		SAFE_SETENV("DOCUMENT_ROOT", dir);
524 
525 		if (tls_peer_cert_provided(c->ctx)) {
526 			SAFE_SETENV("AUTH_TYPE", "Certificate");
527 			SAFE_SETENV("REMOTE_USER", tls_peer_cert_subject(c->ctx));
528 			SAFE_SETENV("TLS_CLIENT_ISSUER", tls_peer_cert_issuer(c->ctx));
529 			SAFE_SETENV("TLS_CLIENT_HASH", tls_peer_cert_hash(c->ctx));
530 		}
531 
532 		execvp(ex, argv);
533 		goto childerr;
534 	}
535 
536 	default:		/* parent */
537 		close(p[1]);
538 		close(c->fd);
539 		c->fd = p[0];
540 		c->child = pid;
541 		mark_nonblock(c->fd);
542 		c->state = S_SENDING;
543 		handle_cgi(fds, c);
544 		return 0;
545 	}
546 
547 err:
548 	if (!start_reply(fds, c, TEMP_FAILURE, "internal server error"))
549 		return 0;
550 	goodbye(fds, c);
551 	return 0;
552 
553 childerr:
554 	dprintf(p[1], "%d internal server error\r\n", TEMP_FAILURE);
555 	close(p[1]);
556 	_exit(1);
557 }
558 
559 void
560 cgi_setpoll_on_child(struct pollfd *fds, struct client *c)
561 {
562 	int fd;
563 
564 	if (c->waiting_on_child)
565 		return;
566 	c->waiting_on_child = 1;
567 
568 	fds->events = POLLIN;
569 
570 	fd = fds->fd;
571 	fds->fd = c->fd;
572 	c->fd = fd;
573 }
574 
575 void
576 cgi_setpoll_on_client(struct pollfd *fds, struct client *c)
577 {
578 	int fd;
579 
580 	if (!c->waiting_on_child)
581 		return;
582 	c->waiting_on_child = 0;
583 
584 	fd = fds->fd;
585 	fds->fd = c->fd;
586 	c->fd = fd;
587 }
588 
589 void
590 handle_cgi(struct pollfd *fds, struct client *c)
591 {
592 	ssize_t r;
593 
594 	/* ensure c->fd is the child and fds->fd the client */
595 	cgi_setpoll_on_client(fds, c);
596 
597 	while (1) {
598 		if (c->len == 0) {
599 			if ((r = read(c->fd, c->sbuf, sizeof(c->sbuf))) == 0)
600 				goto end;
601 			if (r == -1) {
602 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
603 					cgi_setpoll_on_child(fds, c);
604 					return;
605 				}
606                                 goto end;
607 			}
608 			c->len = r;
609 			c->off = 0;
610 		}
611 
612 		while (c->len > 0) {
613 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
614 			case -1:
615 				goto end;
616 
617 			case TLS_WANT_POLLOUT:
618 				fds->events = POLLOUT;
619 				return;
620 
621 			case TLS_WANT_POLLIN:
622 				fds->events = POLLIN;
623 				return;
624 
625 			default:
626                                 c->off += r;
627 				c->len -= r;
628 				break;
629 			}
630 		}
631 	}
632 
633 end:
634 	goodbye(fds, c);
635 }
636 
637 void
638 send_file(char *path, char *query, struct pollfd *fds, struct client *c)
639 {
640 	ssize_t ret, len;
641 
642 	if (c->fd == -1) {
643 		if (!open_file(path, query, fds, c))
644 			return;
645 		c->state = S_SENDING;
646 	}
647 
648 	len = (c->buf + c->len) - c->i;
649 
650 	while (len > 0) {
651 		switch (ret = tls_write(c->ctx, c->i, len)) {
652 		case -1:
653 			LOG(c, "tls_write: %s", tls_error(c->ctx));
654 			goodbye(fds, c);
655 			return;
656 
657 		case TLS_WANT_POLLIN:
658 			fds->events = POLLIN;
659 			return;
660 
661 		case TLS_WANT_POLLOUT:
662 			fds->events = POLLOUT;
663 			return;
664 
665 		default:
666 			c->i += ret;
667 			len -= ret;
668 			break;
669 		}
670 	}
671 
672 	goodbye(fds, c);
673 }
674 
675 void
676 send_dir(char *path, struct pollfd *fds, struct client *client)
677 {
678 	char fpath[PATHBUF];
679 	size_t len;
680 
681 	bzero(fpath, PATHBUF);
682 
683 	if (path[0] != '.')
684 		fpath[0] = '.';
685 
686 	/* this cannot fail since sizeof(fpath) > maxlen of path */
687 	strlcat(fpath, path, PATHBUF);
688 	len = strlen(fpath);
689 
690 	/* add a trailing / in case. */
691 	if (fpath[len-1] != '/') {
692 		fpath[len] = '/';
693 	}
694 
695 	strlcat(fpath, "index.gmi", sizeof(fpath));
696 
697 	send_file(fpath, NULL, fds, client);
698 }
699 
700 void
701 handle(struct pollfd *fds, struct client *client)
702 {
703 	char buf[GEMINI_URL_LEN];
704 	char *path;
705 	char *query;
706 
707 	switch (client->state) {
708 	case S_OPEN:
709 		bzero(buf, GEMINI_URL_LEN);
710 		switch (tls_read(client->ctx, buf, sizeof(buf)-1)) {
711 		case -1:
712 			LOG(client, "tls_read: %s", tls_error(client->ctx));
713 			goodbye(fds, client);
714 			return;
715 
716 		case TLS_WANT_POLLIN:
717 			fds->events = POLLIN;
718 			return;
719 
720 		case TLS_WANT_POLLOUT:
721 			fds->events = POLLOUT;
722 			return;
723 		}
724 
725 		if (!url_trim(client, buf)) {
726 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
727 				return;
728 			goodbye(fds, client);
729 			return;
730 		}
731 
732 		if ((path = url_start_of_request(buf)) == NULL) {
733 			if (!start_reply(fds, client, BAD_REQUEST, "bad request"))
734 				return;
735 			goodbye(fds, client);
736 			return;
737 		}
738 
739 		query = adjust_path(path);
740 		LOG(client, "get %s%s%s", path,
741 		    query ? "?" : "",
742 		    query ? query : "");
743 
744 		send_file(path, query, fds, client);
745 		break;
746 
747 	case S_INITIALIZING:
748 		if (!start_reply(fds, client, client->code, client->meta))
749 			return;
750 
751 		if (client->code != SUCCESS) {
752 			/* we don't need a body */
753 			goodbye(fds, client);
754 			return;
755 		}
756 
757 		client->state = S_SENDING;
758 
759 		/* fallthrough */
760 
761 	case S_SENDING:
762 		if (client->child != -1)
763 			handle_cgi(fds, client);
764 		else
765 			send_file(NULL, NULL, fds, client);
766 		break;
767 
768 	case S_CLOSING:
769 		goodbye(fds, client);
770 		break;
771 
772 	default:
773 		/* unreachable */
774 		abort();
775 	}
776 }
777 
778 void
779 mark_nonblock(int fd)
780 {
781 	int flags;
782 
783 	if ((flags = fcntl(fd, F_GETFL)) == -1)
784 		err(1, "fcntl(F_GETFL)");
785 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
786 		err(1, "fcntl(F_SETFL)");
787 }
788 
789 int
790 make_socket(int port, int family)
791 {
792 	int sock, v;
793 	struct sockaddr_in addr4;
794 	struct sockaddr_in6 addr6;
795 	struct sockaddr *addr;
796 	socklen_t len;
797 
798         switch (family) {
799 	case AF_INET:
800 		bzero(&addr4, sizeof(addr4));
801 		addr4.sin_family = family;
802 		addr4.sin_port = htons(port);
803 		addr4.sin_addr.s_addr = INADDR_ANY;
804 		addr = (struct sockaddr*)&addr4;
805 		len = sizeof(addr4);
806 		break;
807 
808 	case AF_INET6:
809 		bzero(&addr6, sizeof(addr6));
810 		addr6.sin6_family = AF_INET6;
811 		addr6.sin6_port = htons(port);
812 		addr6.sin6_addr = in6addr_any;
813 		addr = (struct sockaddr*)&addr6;
814 		len = sizeof(addr6);
815 		break;
816 
817 	default:
818 		/* unreachable */
819 		abort();
820 	}
821 
822 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
823 		err(1, "socket");
824 
825 	v = 1;
826 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
827 		err(1, "setsockopt(SO_REUSEADDR)");
828 
829 	v = 1;
830 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
831 		err(1, "setsockopt(SO_REUSEPORT)");
832 
833 	mark_nonblock(sock);
834 
835 	if (bind(sock, addr, len) == -1)
836 		err(1, "bind");
837 
838 	if (listen(sock, 16) == -1)
839 		err(1, "listen");
840 
841 	return sock;
842 }
843 
844 void
845 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
846 {
847 	int i, fd;
848 	struct sockaddr_in addr;
849 	socklen_t len;
850 
851 	len = sizeof(addr);
852 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
853 		if (errno == EWOULDBLOCK)
854 			return;
855 		err(1, "accept");
856 	}
857 
858 	mark_nonblock(fd);
859 
860 	for (i = 0; i < MAX_USERS; ++i) {
861 		if (fds[i].fd == -1) {
862 			bzero(&clients[i], sizeof(struct client));
863 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
864 				break; /* goodbye fd! */
865 
866 			fds[i].fd = fd;
867 			fds[i].events = POLLIN;
868 
869 			clients[i].state = S_OPEN;
870 			clients[i].fd = -1;
871 			clients[i].child = -1;
872 			clients[i].buf = MAP_FAILED;
873 			clients[i].af = AF_INET;
874 			clients[i].addr = addr.sin_addr;
875 
876 			connected_clients++;
877 			return;
878 		}
879 	}
880 
881 	close(fd);
882 }
883 
884 void
885 goodbye(struct pollfd *pfd, struct client *c)
886 {
887 	ssize_t ret;
888 
889 	c->state = S_CLOSING;
890 
891 	ret = tls_close(c->ctx);
892 	if (ret == TLS_WANT_POLLIN) {
893 		pfd->events = POLLIN;
894 		return;
895 	}
896 	if (ret == TLS_WANT_POLLOUT) {
897 		pfd->events = POLLOUT;
898 		return;
899 	}
900 
901 	connected_clients--;
902 
903 	tls_free(c->ctx);
904 	c->ctx = NULL;
905 
906 	if (c->buf != MAP_FAILED)
907 		munmap(c->buf, c->len);
908 
909 	if (c->fd != -1)
910 		close(c->fd);
911 
912 	close(pfd->fd);
913 	pfd->fd = -1;
914 }
915 
916 void
917 loop(struct tls *ctx, int sock)
918 {
919 	int i, todo;
920 	struct client clients[MAX_USERS];
921 	struct pollfd fds[MAX_USERS];
922 
923 	for (i = 0; i < MAX_USERS; ++i) {
924 		fds[i].fd = -1;
925 		fds[i].events = POLLIN;
926 		bzero(&clients[i], sizeof(struct client));
927 	}
928 
929 	fds[0].fd = sock;
930 
931 	for (;;) {
932 		if ((todo = poll(fds, MAX_USERS, INFTIM)) == -1) {
933 			if (errno == EINTR) {
934                                 warnx("connected clients: %d", connected_clients);
935 				continue;
936 			}
937 			err(1, "poll");
938 		}
939 
940 		for (i = 0; i < MAX_USERS; i++) {
941 			assert(i < MAX_USERS);
942 
943 			if (fds[i].revents == 0)
944 				continue;
945 
946 			if (fds[i].revents & (POLLERR|POLLNVAL))
947 				err(1, "bad fd %d", fds[i].fd);
948 
949 			if (fds[i].revents & POLLHUP) {
950 				/* fds[i] may be the fd of the stdin
951 				 * of a cgi script that has exited. */
952 				if (!clients[i].waiting_on_child) {
953 					goodbye(&fds[i], &clients[i]);
954 					continue;
955 				}
956 			}
957 
958 			todo--;
959 
960 			if (i == 0) { /* new client */
961 				do_accept(sock, ctx, fds, clients);
962 				continue;
963 			}
964 
965 			handle(&fds[i], &clients[i]);
966 		}
967 	}
968 }
969 
970 void
971 usage(const char *me)
972 {
973 	fprintf(stderr,
974 	    "USAGE: %s [-h] [-c cert.pem] [-d docs] [-k key.pem] "
975 	    "[-l logfile] [-p port] [-x cgi-bin]\n",
976 	    me);
977 }
978 
979 int
980 main(int argc, char **argv)
981 {
982 	const char *cert = "cert.pem", *key = "key.pem";
983 	struct tls *ctx = NULL;
984 	struct tls_config *conf;
985 	int sock, ch;
986 
987 	signal(SIGPIPE, SIG_IGN);
988 	signal(SIGCHLD, SIG_IGN);
989 
990 #ifdef SIGINFO
991 	signal(SIGINFO, siginfo_handler);
992 #endif
993 	signal(SIGUSR2, siginfo_handler);
994 
995 	connected_clients = 0;
996 
997 	dir = "docs/";
998 	logfd = 2;		/* stderr */
999 	cgi = NULL;
1000 	port = 1965;
1001 
1002 	while ((ch = getopt(argc, argv, "c:d:hk:l:p:x:")) != -1) {
1003 		switch (ch) {
1004 		case 'c':
1005 			cert = optarg;
1006 			break;
1007 
1008 		case 'd':
1009 			dir = optarg;
1010 			break;
1011 
1012 		case 'h':
1013 			usage(*argv);
1014 			return 0;
1015 
1016 		case 'k':
1017 			key = optarg;
1018 			break;
1019 
1020 		case 'l':
1021 			/* open log file or create it with 644 */
1022 			if ((logfd = open(optarg, O_WRONLY | O_CREAT | O_CLOEXEC,
1023 					S_IRUSR | S_IWUSR | S_IRGRP | S_IWOTH)) == -1)
1024 				err(1, "%s", optarg);
1025 			break;
1026 
1027 		case 'p': {
1028 			char *ep;
1029 			long lval;
1030 
1031 			errno = 0;
1032 			lval = strtol(optarg, &ep, 10);
1033 			if (optarg[0] == '\0' || *ep != '\0')
1034 				err(1, "not a number: %s", optarg);
1035 			if (lval < 0 || lval > UINT16_MAX)
1036 				err(1, "port number out of range: %s", optarg);
1037 			port = lval;
1038 			break;
1039 		}
1040 
1041 		case 'x':
1042 			cgi = optarg;
1043 			break;
1044 
1045 		default:
1046 			usage(*argv);
1047 			return 1;
1048 		}
1049 	}
1050 
1051 	if ((conf = tls_config_new()) == NULL)
1052 		err(1, "tls_config_new");
1053 
1054 	/* optionally accept client certs, but don't try to verify them */
1055 	tls_config_verify_client_optional(conf);
1056 	tls_config_insecure_noverifycert(conf);
1057 
1058 	if (tls_config_set_protocols(conf,
1059 	    TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3) == -1)
1060 		err(1, "tls_config_set_protocols");
1061 
1062 	if (tls_config_set_cert_file(conf, cert) == -1)
1063 		err(1, "tls_config_set_cert_file: %s", cert);
1064 
1065 	if (tls_config_set_key_file(conf, key) == -1)
1066 		err(1, "tls_config_set_key_file: %s", key);
1067 
1068 	if ((ctx = tls_server()) == NULL)
1069 		err(1, "tls_server");
1070 
1071 	if (tls_configure(ctx, conf) == -1)
1072 		errx(1, "tls_configure: %s", tls_error(ctx));
1073 
1074 	sock = make_socket(port, AF_INET);
1075 
1076 	if ((dirfd = open(dir, O_RDONLY | O_DIRECTORY)) == -1)
1077 		err(1, "open: %s", dir);
1078 
1079 	if (cgi != NULL) {
1080 		if (unveil(dir, "rx") == -1)
1081 			err(1, "unveil");
1082 		if (pledge("stdio rpath inet proc exec", NULL) == -1)
1083 			err(1, "pledge");
1084 	} else {
1085 		if (unveil(dir, "r") == -1)
1086 			err(1, "unveil");
1087 		if (pledge("stdio rpath inet", NULL) == -1)
1088 			err(1, "pledge");
1089 	}
1090 
1091 	loop(ctx, sock);
1092 
1093 	close(sock);
1094 	tls_free(ctx);
1095 	tls_config_free(conf);
1096 }