1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 /*
18  * TODO:
19  *  - move the various
20  *	imsg_compose(...);
21  *	imsg_flush(...);
22  *    to something more asynchronous
23  */
24 
25 #include <telescope.h>
26 
27 #include <sys/types.h>
28 #include <sys/socket.h>
29 
30 #include <netinet/in.h>
31 
32 #include <assert.h>
33 #include <ctype.h>
34 #include <errno.h>
35 #include <netdb.h>
36 #include <stdarg.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <tls.h>
41 #include <unistd.h>
42 
43 #if HAVE_ASR_RUN
44 # include <asr.h>
45 #endif
46 
47 static struct event		 imsgev;
48 static struct tls_config	*tlsconf;
49 static struct imsgbuf		*ibuf;
50 
51 struct req;
52 
53 static void		 die(void) __attribute__((__noreturn__));
54 
55 #if HAVE_ASR_RUN
56 static void		 try_to_connect(int, short, void*);
57 static void		 query_done(struct asr_result*, void*);
58 static void		 async_conn_towards(struct req*);
59 #else
60 static char		*xasprintf(const char*, ...);
61 static int 		 blocking_conn_towards(struct url*, char**);
62 #endif
63 
64 static void		 close_with_err(struct req*, const char*);
65 static void		 close_with_errf(struct req*, const char*, ...) __attribute__((format(printf, 2, 3)));
66 static struct req	*req_by_id(uint32_t);
67 static struct req	*req_by_id_try(uint32_t);
68 
69 static void		 setup_tls(struct req*);
70 static void		 do_handshake(int, short, void*);
71 static void		 write_request(int, short, void*);
72 static void		 read_reply(int, short, void*);
73 static void		 parse_reply(struct req*);
74 static void		 copy_body(int, short, void*);
75 
76 static void		 handle_get(struct imsg*, size_t);
77 static void		 handle_cert_status(struct imsg*, size_t);
78 static void		 handle_proceed(struct imsg*, size_t);
79 static void		 handle_stop(struct imsg*, size_t);
80 static void		 handle_quit(struct imsg*, size_t);
81 static void		 handle_dispatch_imsg(int, short, void*);
82 
83 /* TODO: making this customizable */
84 struct timeval timeout_for_handshake = { 5, 0 };
85 
86 static imsg_handlerfn *handlers[] = {
87 	[IMSG_GET] = handle_get,
88 	[IMSG_CERT_STATUS] = handle_cert_status,
89 	[IMSG_PROCEED] = handle_proceed,
90 	[IMSG_STOP] = handle_stop,
91 	[IMSG_QUIT] = handle_quit,
92 };
93 
94 typedef void (*statefn)(int, short, void*);
95 
96 TAILQ_HEAD(, req) reqhead;
97 /* a pending request */
98 struct req {
99 	struct event		 ev;
100 	struct url		 url;
101 	uint32_t		 id;
102 	int			 fd;
103 	struct tls		*ctx;
104 	char			 buf[1024];
105 	size_t			 off;
106 
107 #if HAVE_ASR_RUN
108 	struct addrinfo		 hints, *servinfo, *p;
109 	struct event_asr	*asrev;
110 #endif
111 
112 	TAILQ_ENTRY(req)	 reqs;
113 };
114 
115 static inline void
116 yield_r(struct req *req, statefn fn, struct timeval *tv)
117 {
118 	event_once(req->fd, EV_READ, fn, req, tv);
119 }
120 
121 static inline void
122 yield_w(struct req *req, statefn fn, struct timeval *tv)
123 {
124 	event_once(req->fd, EV_WRITE, fn, req, tv);
125 }
126 
127 static inline void
128 advance_buf(struct req *req, size_t len)
129 {
130 	assert(len <= req->off);
131 
132 	req->off -= len;
133 	memmove(req->buf, req->buf + len, req->off);
134 }
135 
136 static void __attribute__((__noreturn__))
137 die(void)
138 {
139 	abort(); 		/* TODO */
140 }
141 
142 #if HAVE_ASR_RUN
143 static void
144 try_to_connect(int fd, short ev, void *d)
145 {
146 	struct req	*req = d;
147 	int		 error = 0;
148 	socklen_t	 len = sizeof(error);
149 
150 	if (req->p == NULL)
151 		goto err;
152 
153 	if (req->fd != -1) {
154 		if (getsockopt(req->fd, SOL_SOCKET, SO_ERROR, &error, &len) == -1)
155 			goto err;
156 		if (error != 0) {
157                         errno = error;
158                         goto err;
159 		}
160 		goto done;
161 	}
162 
163 	req->fd = socket(req->p->ai_family, req->p->ai_socktype, req->p->ai_protocol);
164 	if (req->fd == -1)
165 		req->p = req->p->ai_next;
166 	else {
167 		mark_nonblock(req->fd);
168 		if (connect(req->fd, req->p->ai_addr, req->p->ai_addrlen) == 0)
169 			goto done;
170 	}
171 	try_to_connect(fd, ev, req);
172 	return;
173 
174 err:
175 	freeaddrinfo(req->servinfo);
176 	close_with_errf(req, "failed to connect to %s",
177 	    req->url.host);
178 	return;
179 
180 done:
181 	freeaddrinfo(req->servinfo);
182 	setup_tls(req);
183 }
184 
185 static void
186 query_done(struct asr_result *res, void *d)
187 {
188 	struct req	*req = d;
189 
190 	req->asrev = NULL;
191 	if (res->ar_gai_errno != 0) {
192 		close_with_errf(req, "failed to resolve %s: %s",
193 		    req->url.host, gai_strerror(res->ar_gai_errno));
194 		return;
195 	}
196 
197 	req->fd = -1;
198 	req->servinfo = res->ar_addrinfo;
199 	req->p = res->ar_addrinfo;
200 	try_to_connect(0, 0, req);
201 }
202 
203 static void
204 async_conn_towards(struct req *req)
205 {
206 	struct asr_query	*q;
207 	const char		*proto = "1965";
208 
209 	if (*req->url.port != '\0')
210 		proto = req->url.port;
211 
212 	req->hints.ai_family = AF_UNSPEC;
213 	req->hints.ai_socktype = SOCK_STREAM;
214 	q = getaddrinfo_async(req->url.host, proto, &req->hints, NULL);
215 	req->asrev = event_asr_run(q, query_done, req);
216 }
217 #else
218 static char *
219 xasprintf(const char *fmt, ...)
220 {
221 	va_list ap;
222 	char *s;
223 
224 	va_start(ap, fmt);
225 	if (vasprintf(&s, fmt, ap) == -1)
226 		s = NULL;
227 	va_end(ap);
228 
229 	return s;
230 }
231 
232 static int
233 blocking_conn_towards(struct url *url, char **err)
234 {
235 	struct addrinfo	 hints, *servinfo, *p;
236 	int		 status, sock;
237 	const char	*proto = "1965";
238 
239 	*err = NULL;
240 
241 	if (*url->port != '\0')
242 		proto = url->port;
243 
244 	memset(&hints, 0, sizeof(hints));
245 	hints.ai_family = AF_UNSPEC;
246 	hints.ai_socktype = SOCK_STREAM;
247 
248 	if ((status = getaddrinfo(url->host, proto, &hints, &servinfo))) {
249 		*err = xasprintf("failed to resolve %s: %s",
250 		    url->host, gai_strerror(status));
251 		return -1;
252 	}
253 
254 	sock = -1;
255 	for (p = servinfo; p != NULL; p = p->ai_next) {
256 		if ((sock = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1)
257 			continue;
258 		if (connect(sock, p->ai_addr, p->ai_addrlen) != -1)
259 			break;
260 		close(sock);
261 	}
262 
263 	if (sock == -1)
264 		*err = xasprintf("couldn't connect to %s", url->host);
265 	else
266 		mark_nonblock(sock);
267 
268 	freeaddrinfo(servinfo);
269 	return sock;
270 }
271 #endif
272 
273 static struct req *
274 req_by_id(uint32_t id)
275 {
276 	struct req *r;
277 
278 	if ((r = req_by_id_try(id)) == NULL)
279 		die();
280 	return r;
281 }
282 
283 static struct req *
284 req_by_id_try(uint32_t id)
285 {
286 	struct req *r;
287 
288 	TAILQ_FOREACH(r, &reqhead, reqs) {
289 		if (r->id == id)
290 			return r;
291 	}
292 
293 	return NULL;
294 }
295 
296 static void
297 close_conn(int fd, short ev, void *d)
298 {
299 	struct req	*req = d;
300 
301 #if HAVE_ASR_RUN
302 	if (req->asrev != NULL)
303 		event_asr_abort(req->asrev);
304 #endif
305 
306 	if (req->ctx != NULL) {
307 		switch (tls_close(req->ctx)) {
308 		case TLS_WANT_POLLIN:
309 			yield_r(req, close_conn, NULL);
310 			return;
311 		case TLS_WANT_POLLOUT:
312 			yield_w(req, close_conn, NULL);
313 			return;
314 		}
315 
316 		tls_free(req->ctx);
317 	}
318 
319 	TAILQ_REMOVE(&reqhead, req, reqs);
320 	if (req->fd != -1)
321 		close(req->fd);
322 	free(req);
323 }
324 
325 static void
326 close_with_err(struct req *req, const char *err)
327 {
328 	imsg_compose(ibuf, IMSG_ERR, req->id, 0, -1, err, strlen(err)+1);
329 	imsg_flush(ibuf);
330 	close_conn(0, 0, req);
331 }
332 
333 static void
334 close_with_errf(struct req *req, const char *fmt, ...)
335 {
336 	va_list	 ap;
337 	char	*s;
338 
339 	va_start(ap, fmt);
340 	if (vasprintf(&s, fmt, ap) == -1)
341 		abort();
342 	va_end(ap);
343 
344 	close_with_err(req, s);
345 	free(s);
346 }
347 
348 static void
349 setup_tls(struct req *req)
350 {
351 	if ((req->ctx = tls_client()) == NULL) {
352 		close_with_errf(req, "tls_client: %s", strerror(errno));
353 		return;
354 	}
355 	if (tls_configure(req->ctx, tlsconf) == -1) {
356 		close_with_errf(req, "tls_configure: %s", tls_error(req->ctx));
357 		return;
358 	}
359 	if (tls_connect_socket(req->ctx, req->fd, req->url.host) == -1) {
360 		close_with_errf(req, "tls_connect_socket: %s", tls_error(req->ctx));
361 		return;
362 	}
363 	yield_w(req, do_handshake, &timeout_for_handshake);
364 }
365 
366 static void
367 do_handshake(int fd, short ev, void *d)
368 {
369 	struct req	*req = d;
370 	const char	*hash;
371 
372 	if (ev == EV_TIMEOUT) {
373 		close_with_err(req, "Timeout loading page");
374 		return;
375 	}
376 
377 	switch (tls_handshake(req->ctx)) {
378 	case TLS_WANT_POLLIN:
379 		yield_r(req, do_handshake, NULL);
380 		return;
381 	case TLS_WANT_POLLOUT:
382 		yield_w(req, do_handshake, NULL);
383 		return;
384 	}
385 
386 	hash = tls_peer_cert_hash(req->ctx);
387 	if (hash == NULL) {
388 		close_with_errf(req, "handshake failed: %s", tls_error(req->ctx));
389 		return;
390 	}
391 	imsg_compose(ibuf, IMSG_CHECK_CERT, req->id, 0, -1, hash, strlen(hash)+1);
392 	imsg_flush(ibuf);
393 }
394 
395 static void
396 write_request(int fd, short ev, void *d)
397 {
398 	struct req	*req = d;
399 	ssize_t		 r;
400 	size_t		 len;
401 	char		 buf[1024];
402 
403 	strlcpy(buf, "gemini://", sizeof(buf));
404 	strlcat(buf, req->url.host, sizeof(buf));
405 	strlcat(buf, "/", sizeof(buf));
406 	strlcat(buf, req->url.path, sizeof(buf));
407 
408 	if (req->url.query[0] != '\0') {
409 		strlcat(buf, "?", sizeof(buf));
410 		strlcat(buf, req->url.query, sizeof(buf));
411 	}
412 
413 	len = strlcat(buf, "\r\n", sizeof(buf));
414 
415 	assert(len <= sizeof(buf));
416 
417 	switch (r = tls_write(req->ctx, buf, len)) {
418 	case -1:
419 		close_with_errf(req, "tls_write: %s", tls_error(req->ctx));
420 		break;
421 	case TLS_WANT_POLLIN:
422 		yield_r(req, write_request, NULL);
423 		break;
424 	case TLS_WANT_POLLOUT:
425 		yield_w(req, write_request, NULL);
426 		break;
427 	default:
428 		/* assume r == len */
429 		(void)r;
430 		yield_r(req, read_reply, NULL);
431 		break;
432 	}
433 }
434 
435 static void
436 read_reply(int fd, short ev, void *d)
437 {
438 	struct req	*req = d;
439 	size_t		 len;
440 	ssize_t		 r;
441 	char		*buf;
442 
443 	buf = req->buf + req->off;
444 	len = sizeof(req->buf) - req->off;
445 
446 	switch (r = tls_read(req->ctx, buf, len)) {
447 	case -1:
448 		close_with_errf(req, "tls_read: %s", tls_error(req->ctx));
449 		break;
450 	case TLS_WANT_POLLIN:
451 		yield_r(req, read_reply, NULL);
452 		break;
453 	case TLS_WANT_POLLOUT:
454 		yield_w(req, read_reply, NULL);
455 		break;
456 	default:
457 		req->off += r;
458 
459 		/* TODO: really watch for \r\n not \n alone */
460 		if (memmem(req->buf, req->off, "\r\n", 2) != NULL)
461 			parse_reply(req);
462 		else if (req->off == sizeof(req->buf))
463 			close_with_err(req, "invalid response");
464 		else
465 			yield_r(req, read_reply, NULL);
466 		break;
467 	}
468 }
469 
470 static void
471 parse_reply(struct req *req)
472 {
473 	int	 code;
474 	char	*e;
475 	size_t	 len;
476 
477 	if (req->off < 4)
478 		goto err;
479 
480 	if (!isdigit(req->buf[0]) || !isdigit(req->buf[1]))
481 		goto err;
482 
483 	code = (req->buf[0] - '0')*10 + (req->buf[1] - '0');
484 
485 	if (!isspace(req->buf[2]))
486 		goto err;
487 
488 	advance_buf(req, 3);
489 	if ((e = memmem(req->buf, req->off, "\r\n", 2)) == NULL)
490 		goto err;
491 
492 	*e = '\0';
493 	e++;
494 	len = e - req->buf;
495 	imsg_compose(ibuf, IMSG_GOT_CODE, req->id, 0, -1, &code, sizeof(code));
496 	imsg_compose(ibuf, IMSG_GOT_META, req->id, 0, -1,
497 	    req->buf, len);
498 	imsg_flush(ibuf);
499 
500 	if (code != 20)
501 		close_conn(0, 0, req);
502 	advance_buf(req, len+1); /* skip \n too */
503 
504 	return;
505 
506 err:
507 	close_with_err(req, "malformed request");
508 }
509 
510 static void
511 copy_body(int fd, short ev, void *d)
512 {
513 	struct req	*req = d;
514 	ssize_t		 r;
515 
516 	for (;;) {
517 		if (req->off != 0) {
518 			imsg_compose(ibuf, IMSG_BUF, req->id, 0, -1,
519 			    req->buf, req->off);
520 			imsg_flush(ibuf);
521 			req->off = 0;
522 		}
523 
524 		switch (r = tls_read(req->ctx, req->buf, sizeof(req->buf))) {
525 		case TLS_WANT_POLLIN:
526 			yield_r(req, copy_body, NULL);
527 			return;
528 		case TLS_WANT_POLLOUT:
529 			yield_w(req, copy_body, NULL);
530 			return;
531 		case 0:
532 			imsg_compose(ibuf, IMSG_EOF, req->id, 0, -1, NULL, 0);
533 			imsg_flush(ibuf);
534 			close_conn(0, 0, req);
535 			return;
536 		default:
537 			req->off = r;
538 		}
539 	}
540 }
541 
542 static void
543 handle_get(struct imsg *imsg, size_t datalen)
544 {
545 	struct req	*req;
546 	const char	*e;
547 	char		*data;
548 
549 	data = imsg->data;
550 
551 	if (data[datalen-1] != '\0')
552 		die();
553 
554 	if ((req = calloc(1, sizeof(*req))) == NULL)
555 		die();
556 
557 	req->id = imsg->hdr.peerid;
558 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
559 
560         if (!url_parse(imsg->data, &req->url, &e)) {
561 		close_with_err(req, e);
562 		return;
563 	}
564 
565 #if HAVE_ASR_RUN
566         async_conn_towards(req);
567 #else
568 	{
569 		char *e = NULL;
570 
571 		if ((req->fd = blocking_conn_towards(&req->url, &err)) == -1) {
572 			close_with_err(req, err);
573 			free(err);
574 		}
575 		setup_tls(req);
576 	}
577 #endif
578 }
579 
580 static void
581 handle_cert_status(struct imsg *imsg, size_t datalen)
582 {
583 	struct req	*req;
584 	int		 is_ok;
585 
586 	req = req_by_id(imsg->hdr.peerid);
587 
588 	if (datalen < sizeof(is_ok))
589 		die();
590 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
591 
592 	if (is_ok)
593 		yield_w(req, write_request, NULL);
594 	else
595 		close_conn(0, 0, req);
596 }
597 
598 static void
599 handle_proceed(struct imsg *imsg, size_t datalen)
600 {
601 	yield_r(req_by_id(imsg->hdr.peerid),
602 	    copy_body, NULL);
603 }
604 
605 static void
606 handle_stop(struct imsg *imsg, size_t datalen)
607 {
608 	struct req	*req;
609 
610 	if ((req = req_by_id_try(imsg->hdr.peerid)) == NULL)
611 		return;
612 	close_conn(0, 0, req);
613 }
614 
615 static void
616 handle_quit(struct imsg *imsg, size_t datalen)
617 {
618 	event_loopbreak();
619 }
620 
621 static void
622 handle_dispatch_imsg(int fd, short ev, void *d)
623 {
624 	struct imsgbuf	*ibuf = d;
625 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
626 }
627 
628 int
629 client_main(struct imsgbuf *b)
630 {
631 	ibuf = b;
632 
633 	TAILQ_INIT(&reqhead);
634 
635 	if ((tlsconf = tls_config_new()) == NULL)
636 		die();
637 	tls_config_insecure_noverifycert(tlsconf);
638 
639 	event_init();
640 
641 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
642 	event_add(&imsgev, NULL);
643 
644 	sandbox_network_process();
645 
646 	event_dispatch();
647 	return 0;
648 }