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Date:: Wed Jan 13 18:40:18 2021 UTC
Message:: track handshakes This alter the current state machine by adding S_HANDSHAKE as the initial state. There, we ensure we did the handshake and we check SNI. ATM we simply continue in S_OPEN, but later we can add virtual host checks there, and skip to S_INITIALIZING with an error state if the client is accessing a wrong host.
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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/stat.h>
19 
20 #include <assert.h>
21 #include <err.h>
22 #include <errno.h>
23 #include <fcntl.h>
24 #include <limits.h>
25 #include <netdb.h>
26 #include <signal.h>
27 #include <stdarg.h>
28 #include <string.h>
29 
30 #include "gmid.h"
31 
32 #define LOGE(c, fmt, ...) logs(LOG_ERR,    c, fmt, __VA_ARGS__)
33 #define LOGN(c, fmt, ...) logs(LOG_NOTICE, c, fmt, __VA_ARGS__)
34 #define LOGI(c, fmt, ...) logs(LOG_INFO,   c, fmt, __VA_ARGS__)
35 #define LOGD(c, fmt, ...) logs(LOG_DEBUG,  c, fmt, __VA_ARGS__)
36 
37 const char *dir, *cgi;
38 int dirfd;
39 int port;
40 int foreground;
41 int connected_clients;
42 
43 struct etm {			/* file extension to mime */
44 	const char	*mime;
45 	const char	*ext;
46 } filetypes[] = {
47 	{"application/pdf",	"pdf"},
48 
49 	{"image/gif",		"gif"},
50 	{"image/jpeg",		"jpg"},
51 	{"image/jpeg",		"jpeg"},
52 	{"image/png",		"png"},
53 	{"image/svg+xml",	"svg"},
54 
55 	{"text/gemini",		"gemini"},
56 	{"text/gemini",		"gmi"},
57 	{"text/markdown",	"markdown"},
58 	{"text/markdown",	"md"},
59 	{"text/plain",		"txt"},
60 	{"text/xml",		"xml"},
61 
62 	{NULL, NULL}
63 };
64 
65 static inline void
66 safe_setenv(const char *name, const char *val)
67 {
68 	if (val == NULL)
69 		val = "";
70 	setenv(name, val, 1);
71 }
72 
73 __attribute__ ((format (printf, 1, 2)))
74 __attribute__ ((__noreturn__))
75 static inline void
76 fatal(const char *fmt, ...)
77 {
78 	va_list ap;
79 
80 	va_start(ap, fmt);
81 
82 	if (foreground) {
83 		vfprintf(stderr, fmt, ap);
84 		fprintf(stderr, "\n");
85 	} else
86 		vsyslog(LOG_DAEMON | LOG_CRIT, fmt, ap);
87 
88 	va_end(ap);
89 	exit(1);
90 }
91 
92 __attribute__ ((format (printf, 3, 4)))
93 static inline void
94 logs(int priority, struct client *c,
95     const char *fmt, ...)
96 {
97 	char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
98 	char *fmted, *s;
99 	size_t len;
100 	int ec;
101 	va_list ap;
102 
103 	va_start(ap, fmt);
104 
105 	len = sizeof(c->addr);
106 	ec = getnameinfo((struct sockaddr*)&c->addr, len,
107 	    hbuf, sizeof(hbuf),
108 	    sbuf, sizeof(sbuf),
109 	    NI_NUMERICHOST | NI_NUMERICSERV);
110 	if (ec != 0)
111 		fatal("getnameinfo: %s", gai_strerror(ec));
112 
113 	if (vasprintf(&fmted, fmt, ap) == -1)
114 		fatal("vasprintf: %s", strerror(errno));
115 
116 	if (foreground)
117 		fprintf(stderr, "%s:%s %s\n", hbuf, sbuf, fmted);
118 	else {
119 		if (asprintf(&s, "%s:%s %s", hbuf, sbuf, fmted) == -1)
120 			fatal("asprintf: %s", strerror(errno));
121 		syslog(priority | LOG_DAEMON, "%s", s);
122 		free(s);
123 	}
124 
125 	free(fmted);
126 
127 	va_end(ap);
128 }
129 
130 void
131 sig_handler(int sig)
132 {
133 	(void)sig;
134 }
135 
136 int
137 starts_with(const char *str, const char *prefix)
138 {
139 	size_t i;
140 
141 	for (i = 0; prefix[i] != '\0'; ++i)
142 		if (str[i] != prefix[i])
143 			return 0;
144 	return 1;
145 }
146 
147 int
148 start_reply(struct pollfd *pfd, struct client *client, int code, const char *reason)
149 {
150 	char buf[1030] = {0}; 	/* status + ' ' + max reply len + \r\n\0 */
151 	int len;
152 	int ret;
153 
154 	client->code = code;
155 	client->meta = reason;
156 	client->state = S_INITIALIZING;
157 
158 	len = snprintf(buf, sizeof(buf), "%d %s\r\n", code, reason);
159 	assert(len < (int)sizeof(buf));
160 	ret = tls_write(client->ctx, buf, len);
161 	if (ret == TLS_WANT_POLLIN) {
162 		pfd->events = POLLIN;
163 		return 0;
164 	}
165 
166 	if (ret == TLS_WANT_POLLOUT) {
167 		pfd->events = POLLOUT;
168 		return 0;
169 	}
170 
171 	return 1;
172 }
173 
174 ssize_t
175 filesize(int fd)
176 {
177 	ssize_t len;
178 
179 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
180 		return -1;
181 	if (lseek(fd, 0, SEEK_SET) == -1)
182 		return -1;
183 	return len;
184 }
185 
186 const char *
187 path_ext(const char *path)
188 {
189 	const char *end;
190 
191 	end = path + strlen(path)-1; /* the last byte before the NUL */
192 	for (; end != path; --end) {
193 		if (*end == '.')
194 			return end+1;
195 		if (*end == '/')
196 			break;
197 	}
198 
199 	return NULL;
200 }
201 
202 const char *
203 mime(const char *path)
204 {
205 	const char *ext, *def = "application/octet-stream";
206 	struct etm *t;
207 
208 	if ((ext = path_ext(path)) == NULL)
209 		return def;
210 
211 	for (t = filetypes; t->mime != NULL; ++t)
212 		if (!strcmp(ext, t->ext))
213 			return t->mime;
214 
215 	return def;
216 }
217 
218 int
219 check_path(struct client *c, const char *path, int *fd)
220 {
221 	struct stat sb;
222 
223 	assert(path != NULL);
224 	if ((*fd = openat(dirfd, *path ? path : ".",
225 		    O_RDONLY | O_NOFOLLOW | O_CLOEXEC)) == -1) {
226 		return FILE_MISSING;
227 	}
228 
229 	if (fstat(*fd, &sb) == -1) {
230 		LOGN(c, "failed stat for %s: %s", path, strerror(errno));
231 		return FILE_MISSING;
232 	}
233 
234 	if (S_ISDIR(sb.st_mode))
235 		return FILE_DIRECTORY;
236 
237 	if (sb.st_mode & S_IXUSR)
238 		return FILE_EXECUTABLE;
239 
240 	return FILE_EXISTS;
241 }
242 
243 /*
244  * the inverse of this algorithm, i.e. starting from the start of the
245  * path + strlen(cgi), and checking if each component, should be
246  * faster.  But it's tedious to write.  This does the opposite: starts
247  * from the end and strip one component at a time, until either an
248  * executable is found or we emptied the path.
249  */
250 int
251 check_for_cgi(char *path, char *query, struct pollfd *fds, struct client *c)
252 {
253 	char *end;
254 	end = strchr(path, '\0');
255 
256 	/* NB: assume CGI is enabled and path matches cgi */
257 
258 	while (end > path) {
259 		/* go up one level.  UNIX paths are simple and POSIX
260 		 * dirname, with its ambiguities on if the given path
261 		 * is changed or not, gives me headaches. */
262 		while (*end != '/')
263 			end--;
264 		*end = '\0';
265 
266 		switch (check_path(c, path, &c->fd)) {
267 		case FILE_EXECUTABLE:
268 			return start_cgi(path, end+1, query, fds,c);
269 		case FILE_MISSING:
270 			break;
271 		default:
272 			goto err;
273 		}
274 
275 		*end = '/';
276 		end--;
277 	}
278 
279 err:
280 	if (!start_reply(fds, c, NOT_FOUND, "not found"))
281 		return 0;
282 	goodbye(fds, c);
283 	return 0;
284 }
285 
286 
287 int
288 open_file(char *fpath, char *query, struct pollfd *fds, struct client *c)
289 {
290 	switch (check_path(c, fpath, &c->fd)) {
291 	case FILE_EXECUTABLE:
292 		if (cgi != NULL && starts_with(fpath, cgi))
293 			return start_cgi(fpath, "", query, fds, c);
294 
295 		/* fallthrough */
296 
297 	case FILE_EXISTS:
298 		if ((c->len = filesize(c->fd)) == -1) {
299 			LOGE(c, "failed to get file size for %s", fpath);
300 			goodbye(fds, c);
301 			return 0;
302 		}
303 
304 		if ((c->buf = mmap(NULL, c->len, PROT_READ, MAP_PRIVATE,
305 			    c->fd, 0)) == MAP_FAILED) {
306 			warn("mmap: %s", fpath);
307 			goodbye(fds, c);
308 			return 0;
309 		}
310 		c->i = c->buf;
311 		return start_reply(fds, c, SUCCESS, mime(fpath));
312 
313 	case FILE_DIRECTORY:
314 		LOGD(c, "%s is a directory, trying %s/index.gmi", fpath, fpath);
315 		close(c->fd);
316 		c->fd = -1;
317 		send_dir(fpath, fds, c);
318 		return 0;
319 
320 	case FILE_MISSING:
321 		if (cgi != NULL && starts_with(fpath, cgi))
322 			return check_for_cgi(fpath, query, fds, c);
323 
324 		if (!start_reply(fds, c, NOT_FOUND, "not found"))
325 			return 0;
326 		goodbye(fds, c);
327 		return 0;
328 
329 	default:
330 		/* unreachable */
331 		abort();
332 	}
333 }
334 
335 int
336 start_cgi(const char *spath, const char *relpath, const char *query,
337     struct pollfd *fds, struct client *c)
338 {
339 	pid_t pid;
340 	int p[2]; 		/* read end, write end */
341 
342 	if (pipe(p) == -1)
343 		goto err;
344 
345 	switch (pid = fork()) {
346 	case -1:
347 		goto err;
348 
349 	case 0: { 		/* child */
350 		char *ex, *requri, *portno;
351 		char addr[NI_MAXHOST];
352 		char *argv[] = { NULL, NULL, NULL };
353 		int ec;
354 
355 		close(p[0]);
356 		if (dup2(p[1], 1) == -1)
357 			goto childerr;
358 
359 		if (inet_ntop(c->af, &c->addr, addr, sizeof(addr)) == NULL)
360 			goto childerr;
361 
362 		ec = getnameinfo((struct sockaddr*)&c->addr, sizeof(c->addr),
363 		    addr, sizeof(addr),
364 		    NULL, 0,
365 		    NI_NUMERICHOST | NI_NUMERICSERV);
366 		if (ec != 0)
367 			goto childerr;
368 
369 		if (asprintf(&portno, "%d", port) == -1)
370 			goto childerr;
371 
372 		if (asprintf(&ex, "%s/%s", dir, spath) == -1)
373 			goto childerr;
374 
375 		if (asprintf(&requri, "%s%s%s", spath,
376 		    *relpath == '\0' ? "" : "/",
377 		    relpath) == -1)
378 			goto childerr;
379 
380 		argv[0] = argv[1] = ex;
381 
382 		/* fix the env */
383 		safe_setenv("GATEWAY_INTERFACE", "CGI/1.1");
384 		safe_setenv("SERVER_SOFTWARE", "gmid");
385 		safe_setenv("SERVER_PORT", portno);
386 		/* setenv("SERVER_NAME", "", 1); */
387 		safe_setenv("SCRIPT_NAME", spath);
388 		safe_setenv("SCRIPT_EXECUTABLE", ex);
389 		safe_setenv("REQUEST_URI", requri);
390 		safe_setenv("REQUEST_RELATIVE", relpath);
391 		safe_setenv("QUERY_STRING", query);
392 		safe_setenv("REMOTE_HOST", addr);
393 		safe_setenv("REMOTE_ADDR", addr);
394 		safe_setenv("DOCUMENT_ROOT", dir);
395 
396 		if (tls_peer_cert_provided(c->ctx)) {
397 			safe_setenv("AUTH_TYPE", "Certificate");
398 			safe_setenv("REMOTE_USER", tls_peer_cert_subject(c->ctx));
399 			safe_setenv("TLS_CLIENT_ISSUER", tls_peer_cert_issuer(c->ctx));
400 			safe_setenv("TLS_CLIENT_HASH", tls_peer_cert_hash(c->ctx));
401 		}
402 
403 		execvp(ex, argv);
404 		goto childerr;
405 	}
406 
407 	default:		/* parent */
408 		close(p[1]);
409 		close(c->fd);
410 		c->fd = p[0];
411 		c->child = pid;
412 		mark_nonblock(c->fd);
413 		c->state = S_SENDING;
414 		handle_cgi(fds, c);
415 		return 0;
416 	}
417 
418 err:
419 	if (!start_reply(fds, c, TEMP_FAILURE, "internal server error"))
420 		return 0;
421 	goodbye(fds, c);
422 	return 0;
423 
424 childerr:
425 	dprintf(p[1], "%d internal server error\r\n", TEMP_FAILURE);
426 	close(p[1]);
427 	_exit(1);
428 }
429 
430 void
431 cgi_poll_on_child(struct pollfd *fds, struct client *c)
432 {
433 	int fd;
434 
435 	if (c->waiting_on_child)
436 		return;
437 	c->waiting_on_child = 1;
438 
439 	fds->events = POLLIN;
440 
441 	fd = fds->fd;
442 	fds->fd = c->fd;
443 	c->fd = fd;
444 }
445 
446 void
447 cgi_poll_on_client(struct pollfd *fds, struct client *c)
448 {
449 	int fd;
450 
451 	if (!c->waiting_on_child)
452 		return;
453 	c->waiting_on_child = 0;
454 
455 	fd = fds->fd;
456 	fds->fd = c->fd;
457 	c->fd = fd;
458 }
459 
460 void
461 handle_cgi(struct pollfd *fds, struct client *c)
462 {
463 	ssize_t r;
464 
465 	/* ensure c->fd is the child and fds->fd the client */
466 	cgi_poll_on_client(fds, c);
467 
468 	while (1) {
469 		if (c->len == 0) {
470 			if ((r = read(c->fd, c->sbuf, sizeof(c->sbuf))) == 0)
471 				goto end;
472 			if (r == -1) {
473 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
474 					cgi_poll_on_child(fds, c);
475 					return;
476 				}
477                                 goto end;
478 			}
479 			c->len = r;
480 			c->off = 0;
481 		}
482 
483 		while (c->len > 0) {
484 			switch (r = tls_write(c->ctx, c->sbuf + c->off, c->len)) {
485 			case -1:
486 				goto end;
487 
488 			case TLS_WANT_POLLOUT:
489 				fds->events = POLLOUT;
490 				return;
491 
492 			case TLS_WANT_POLLIN:
493 				fds->events = POLLIN;
494 				return;
495 
496 			default:
497                                 c->off += r;
498 				c->len -= r;
499 				break;
500 			}
501 		}
502 	}
503 
504 end:
505 	goodbye(fds, c);
506 }
507 
508 void
509 send_file(char *path, char *query, struct pollfd *fds, struct client *c)
510 {
511 	ssize_t ret, len;
512 
513 	if (c->fd == -1) {
514 		if (!open_file(path, query, fds, c))
515 			return;
516 		c->state = S_SENDING;
517 	}
518 
519 	len = (c->buf + c->len) - c->i;
520 
521 	while (len > 0) {
522 		switch (ret = tls_write(c->ctx, c->i, len)) {
523 		case -1:
524 			LOGE(c, "tls_write: %s", tls_error(c->ctx));
525 			goodbye(fds, c);
526 			return;
527 
528 		case TLS_WANT_POLLIN:
529 			fds->events = POLLIN;
530 			return;
531 
532 		case TLS_WANT_POLLOUT:
533 			fds->events = POLLOUT;
534 			return;
535 
536 		default:
537 			c->i += ret;
538 			len -= ret;
539 			break;
540 		}
541 	}
542 
543 	goodbye(fds, c);
544 }
545 
546 void
547 send_dir(char *path, struct pollfd *fds, struct client *client)
548 {
549 	char fpath[PATHBUF];
550 	size_t len;
551 
552 	bzero(fpath, PATHBUF);
553 
554 	if (path[0] != '.')
555 		fpath[0] = '.';
556 
557 	/* this cannot fail since sizeof(fpath) > maxlen of path */
558 	strlcat(fpath, path, PATHBUF);
559 	len = strlen(fpath);
560 
561 	/* add a trailing / in case. */
562 	if (fpath[len-1] != '/') {
563 		fpath[len] = '/';
564 	}
565 
566 	strlcat(fpath, "index.gmi", sizeof(fpath));
567 
568 	send_file(fpath, NULL, fds, client);
569 }
570 
571 void
572 handle_handshake(struct pollfd *fds, struct client *c)
573 {
574 	switch (tls_handshake(c->ctx)) {
575 	case 0:  /* success */
576 	case -1: /* already handshaked */
577 		break;
578 	case TLS_WANT_POLLIN:
579 		fds->events = POLLIN;
580 		return;
581 	case TLS_WANT_POLLOUT:
582 		fds->events = POLLOUT;
583 		return;
584 	default:
585 		/* unreachable */
586 		abort();
587 	}
588 
589 	/* TODO: check SNI here */
590 	logs(LOG_DEBUG, c, "client wanted to talk to: %s", tls_conn_servername(c->ctx));
591 
592 	c->state = S_OPEN;
593 	handle_open_conn(fds, c);
594 }
595 
596 void
597 handle_open_conn(struct pollfd *fds, struct client *c)
598 {
599 	char buf[GEMINI_URL_LEN];
600 	const char *parse_err = "invalid request";
601 	struct iri iri;
602 
603 	bzero(buf, sizeof(buf));
604 
605 	switch (tls_read(c->ctx, buf, sizeof(buf)-1)) {
606 	case -1:
607 		LOGE(c, "tls_read: %s", tls_error(c->ctx));
608 		goodbye(fds, c);
609 		return;
610 
611 	case TLS_WANT_POLLIN:
612 		fds->events = POLLIN;
613 		return;
614 
615 	case TLS_WANT_POLLOUT:
616 		fds->events = POLLOUT;
617 		return;
618 	}
619 
620 	if (!trim_req_iri(buf) || !parse_iri(buf, &iri, &parse_err)) {
621 		if (!start_reply(fds, c, BAD_REQUEST, parse_err))
622 			return;
623 		goodbye(fds, c);
624 		return;
625 	}
626 
627 	if (strcmp(iri.schema, "gemini")) {
628 		if (!start_reply(fds, c, PROXY_REFUSED, "won't proxy request"))
629 			return;
630 		goodbye(fds, c);
631 		return;
632 	}
633 
634 	LOGI(c, "GET %s%s%s",
635 		*iri.path ? iri.path : "/",
636 		*iri.query ? "?" : "",
637 		*iri.query ? iri.query : "");
638 
639 	send_file(iri.path, iri.query, fds, c);
640 }
641 
642 void
643 handle(struct pollfd *fds, struct client *client)
644 {
645 	switch (client->state) {
646 	case S_HANDSHAKE:
647 		handle_handshake(fds, client);
648 		break;
649 
650 	case S_OPEN:
651                 handle_open_conn(fds, client);
652 		break;
653 
654 	case S_INITIALIZING:
655 		if (!start_reply(fds, client, client->code, client->meta))
656 			return;
657 
658 		if (client->code != SUCCESS) {
659 			/* we don't need a body */
660 			goodbye(fds, client);
661 			return;
662 		}
663 
664 		client->state = S_SENDING;
665 
666 		/* fallthrough */
667 
668 	case S_SENDING:
669 		if (client->child != -1)
670 			handle_cgi(fds, client);
671 		else
672 			send_file(NULL, NULL, fds, client);
673 		break;
674 
675 	case S_CLOSING:
676 		goodbye(fds, client);
677 		break;
678 
679 	default:
680 		/* unreachable */
681 		abort();
682 	}
683 }
684 
685 void
686 mark_nonblock(int fd)
687 {
688 	int flags;
689 
690 	if ((flags = fcntl(fd, F_GETFL)) == -1)
691 		fatal("fcntl(F_GETFL): %s", strerror(errno));
692 	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
693 		fatal("fcntl(F_SETFL): %s", strerror(errno));
694 }
695 
696 int
697 make_socket(int port, int family)
698 {
699 	int sock, v;
700 	struct sockaddr_in addr4;
701 	struct sockaddr_in6 addr6;
702 	struct sockaddr *addr;
703 	socklen_t len;
704 
705         switch (family) {
706 	case AF_INET:
707 		bzero(&addr4, sizeof(addr4));
708 		addr4.sin_family = family;
709 		addr4.sin_port = htons(port);
710 		addr4.sin_addr.s_addr = INADDR_ANY;
711 		addr = (struct sockaddr*)&addr4;
712 		len = sizeof(addr4);
713 		break;
714 
715 	case AF_INET6:
716 		bzero(&addr6, sizeof(addr6));
717 		addr6.sin6_family = AF_INET6;
718 		addr6.sin6_port = htons(port);
719 		addr6.sin6_addr = in6addr_any;
720 		addr = (struct sockaddr*)&addr6;
721 		len = sizeof(addr6);
722 		break;
723 
724 	default:
725 		/* unreachable */
726 		abort();
727 	}
728 
729 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
730 		fatal("socket: %s", strerror(errno));
731 
732 	v = 1;
733 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
734 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
735 
736 	v = 1;
737 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
738 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
739 
740 	mark_nonblock(sock);
741 
742 	if (bind(sock, addr, len) == -1)
743 		fatal("bind: %s", strerror(errno));
744 
745 	if (listen(sock, 16) == -1)
746 		fatal("listen: %s", strerror(errno));
747 
748 	return sock;
749 }
750 
751 void
752 do_accept(int sock, struct tls *ctx, struct pollfd *fds, struct client *clients)
753 {
754 	int i, fd;
755 	struct sockaddr_storage addr;
756 	socklen_t len;
757 
758 	len = sizeof(addr);
759 	if ((fd = accept(sock, (struct sockaddr*)&addr, &len)) == -1) {
760 		if (errno == EWOULDBLOCK)
761 			return;
762 		fatal("accept: %s", strerror(errno));
763 	}
764 
765 	mark_nonblock(fd);
766 
767 	for (i = 0; i < MAX_USERS; ++i) {
768 		if (fds[i].fd == -1) {
769 			bzero(&clients[i], sizeof(struct client));
770 			if (tls_accept_socket(ctx, &clients[i].ctx, fd) == -1)
771 				break; /* goodbye fd! */
772 
773 			fds[i].fd = fd;
774 			fds[i].events = POLLIN;
775 
776 			clients[i].state = S_HANDSHAKE;
777 			clients[i].fd = -1;
778 			clients[i].child = -1;
779 			clients[i].buf = MAP_FAILED;
780 			clients[i].af = AF_INET;
781 			clients[i].addr = addr;
782 
783 			connected_clients++;
784 			return;
785 		}
786 	}
787 
788 	close(fd);
789 }
790 
791 void
792 goodbye(struct pollfd *pfd, struct client *c)
793 {
794 	ssize_t ret;
795 
796 	c->state = S_CLOSING;
797 
798 	ret = tls_close(c->ctx);
799 	if (ret == TLS_WANT_POLLIN) {
800 		pfd->events = POLLIN;
801 		return;
802 	}
803 	if (ret == TLS_WANT_POLLOUT) {
804 		pfd->events = POLLOUT;
805 		return;
806 	}
807 
808 	connected_clients--;
809 
810 	tls_free(c->ctx);
811 	c->ctx = NULL;
812 
813 	if (c->buf != MAP_FAILED)
814 		munmap(c->buf, c->len);
815 
816 	if (c->fd != -1)
817 		close(c->fd);
818 
819 	close(pfd->fd);
820 	pfd->fd = -1;
821 }
822 
823 void
824 loop(struct tls *ctx, int sock4, int sock6)
825 {
826 	int i;
827 	struct client clients[MAX_USERS];
828 	struct pollfd fds[MAX_USERS];
829 
830 	for (i = 0; i < MAX_USERS; ++i) {
831 		fds[i].fd = -1;
832 		fds[i].events = POLLIN;
833 		bzero(&clients[i], sizeof(struct client));
834 	}
835 
836 	fds[0].fd = sock4;
837 	fds[1].fd = sock6;
838 
839 	for (;;) {
840 		if (poll(fds, MAX_USERS, INFTIM) == -1) {
841 			if (errno == EINTR) {
842                                 warnx("connected clients: %d",
843 				    connected_clients);
844 				continue;
845 			}
846 			fatal("poll: %s", strerror(errno));
847 		}
848 
849 		for (i = 0; i < MAX_USERS; i++) {
850 			if (fds[i].revents == 0)
851 				continue;
852 
853 			if (fds[i].revents & (POLLERR|POLLNVAL))
854 				fatal("bad fd %d: %s", fds[i].fd,
855 				    strerror(errno));
856 
857 			if (fds[i].revents & POLLHUP) {
858 				/* fds[i] may be the fd of the stdin
859 				 * of a cgi script that has exited. */
860 				if (!clients[i].waiting_on_child) {
861 					goodbye(&fds[i], &clients[i]);
862 					continue;
863 				}
864 			}
865 
866 			if (fds[i].fd == sock4)
867 				do_accept(sock4, ctx, fds, clients);
868 			else if (fds[i].fd == sock6)
869 				do_accept(sock6, ctx, fds, clients);
870 			else
871 				handle(&fds[i], &clients[i]);
872 		}
873 	}
874 }
875 
876 char *
877 absolutify_path(const char *path)
878 {
879 	char *wd, *r;
880 
881 	if (*path == '/')
882 		return strdup(path);
883 
884 	wd = getwd(NULL);
885 	if (asprintf(&r, "%s/%s", wd, path) == -1)
886 		err(1, "asprintf");
887 	free(wd);
888 	return r;
889 }
890 
891 void
892 usage(const char *me)
893 {
894 	fprintf(stderr,
895 	    "USAGE: %s [-h] [-c cert.pem] [-d docs] [-k key.pem] "
896 	    "[-l logfile] [-p port] [-x cgi-bin]\n",
897 	    me);
898 }
899 
900 int
901 main(int argc, char **argv)
902 {
903 	const char *cert = "cert.pem", *key = "key.pem";
904 	struct tls *ctx = NULL;
905 	struct tls_config *conf;
906 	int sock4, sock6, enable_ipv6, ch;
907 	connected_clients = 0;
908 
909 	if ((dir = absolutify_path("docs")) == NULL)
910 		err(1, "absolutify_path");
911 
912 	cgi = NULL;
913 	port = 1965;
914 	foreground = 0;
915 	enable_ipv6 = 0;
916 
917 	while ((ch = getopt(argc, argv, "6c:d:fhk:p:x:")) != -1) {
918 		switch (ch) {
919 		case '6':
920 			enable_ipv6 = 1;
921 			break;
922 
923 		case 'c':
924 			cert = optarg;
925 			break;
926 
927 		case 'd':
928 			free((char*)dir);
929 			if ((dir = absolutify_path(optarg)) == NULL)
930 				err(1, "absolutify_path");
931 			break;
932 
933 		case 'f':
934 			foreground = 1;
935 			break;
936 
937 		case 'h':
938 			usage(*argv);
939 			return 0;
940 
941 		case 'k':
942 			key = optarg;
943 			break;
944 
945 		case 'p': {
946 			char *ep;
947 			long lval;
948 
949 			errno = 0;
950 			lval = strtol(optarg, &ep, 10);
951 			if (optarg[0] == '\0' || *ep != '\0')
952 				err(1, "not a number: %s", optarg);
953 			if (lval < 0 || lval > UINT16_MAX)
954 				err(1, "port number out of range: %s", optarg);
955 			port = lval;
956 			break;
957 		}
958 
959 		case 'x':
960 			cgi = optarg;
961 			break;
962 
963 		default:
964 			usage(*argv);
965 			return 1;
966 		}
967 	}
968 
969 	signal(SIGPIPE, SIG_IGN);
970 	signal(SIGCHLD, SIG_IGN);
971 
972 #ifdef SIGINFO
973 	signal(SIGINFO, sig_handler);
974 #endif
975 	signal(SIGUSR2, sig_handler);
976 
977 	if (!foreground)
978 		signal(SIGHUP, SIG_IGN);
979 
980 	if ((conf = tls_config_new()) == NULL)
981 		err(1, "tls_config_new");
982 
983 	/* optionally accept client certs, but don't try to verify them */
984 	tls_config_verify_client_optional(conf);
985 	tls_config_insecure_noverifycert(conf);
986 
987 	if (tls_config_set_protocols(conf,
988 	    TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3) == -1)
989 		err(1, "tls_config_set_protocols");
990 
991 	if (tls_config_set_cert_file(conf, cert) == -1)
992 		err(1, "tls_config_set_cert_file: %s", cert);
993 
994 	if (tls_config_set_key_file(conf, key) == -1)
995 		err(1, "tls_config_set_key_file: %s", key);
996 
997 	if ((ctx = tls_server()) == NULL)
998 		err(1, "tls_server");
999 
1000 	if (tls_configure(ctx, conf) == -1)
1001 		errx(1, "tls_configure: %s", tls_error(ctx));
1002 
1003 	sock4 = make_socket(port, AF_INET);
1004 	if (enable_ipv6)
1005 		sock6 = make_socket(port, AF_INET6);
1006 	else
1007 		sock6 = -1;
1008 
1009 	if ((dirfd = open(dir, O_RDONLY | O_DIRECTORY)) == -1)
1010 		err(1, "open: %s", dir);
1011 
1012 	if (!foreground && daemon(0, 1) == -1)
1013 		exit(1);
1014 
1015 	if (unveil(dir, "rx") == -1)
1016 		err(1, "unveil");
1017 
1018 	if (pledge("stdio rpath inet proc exec", NULL) == -1)
1019 		err(1, "pledge");
1020 
1021 	/* drop proc and exec if cgi isn't enabled */
1022 	if (cgi == NULL && pledge("stdio rpath inet", NULL) == -1)
1023 		err(1, "pledge");
1024 
1025 	loop(ctx, sock4, sock6);
1026 
1027 	close(sock4);
1028 	close(sock6);
1029 	tls_free(ctx);
1030 	tls_config_free(conf);
1031 
1032 	return 0;
1033 }