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 static struct event		 imsgev;
44 static struct tls_config	*tlsconf;
45 static struct imsgbuf		*ibuf;
46 
47 struct req;
48 
49 static void		 die(void) __attribute__((__noreturn__));
50 static char		*xasprintf(const char*, ...);
51 static int 		 conn_towards(struct url*, char**);
52 
53 static void		 close_with_err(struct req*, const char*);
54 static void		 close_with_errf(struct req*, const char*, ...) __attribute__((format(printf, 2, 3)));
55 static struct req	*req_by_id(uint32_t);
56 static struct req	*req_by_id_try(uint32_t);
57 
58 static void		 do_handshake(int, short, void*);
59 static void		 write_request(int, short, void*);
60 static void		 read_reply(int, short, void*);
61 static void		 parse_reply(struct req*);
62 static void		 copy_body(int, short, void*);
63 
64 static void		 handle_get(struct imsg*, size_t);
65 static void		 handle_cert_status(struct imsg*, size_t);
66 static void		 handle_proceed(struct imsg*, size_t);
67 static void		 handle_stop(struct imsg*, size_t);
68 static void		 handle_quit(struct imsg*, size_t);
69 static void		 handle_dispatch_imsg(int, short, void*);
70 
71 /* TODO: making this customizable */
72 struct timeval timeout_for_handshake = { 5, 0 };
73 
74 static imsg_handlerfn *handlers[] = {
75 	[IMSG_GET] = handle_get,
76 	[IMSG_CERT_STATUS] = handle_cert_status,
77 	[IMSG_PROCEED] = handle_proceed,
78 	[IMSG_STOP] = handle_stop,
79 	[IMSG_QUIT] = handle_quit,
80 };
81 
82 typedef void (*statefn)(int, short, void*);
83 
84 TAILQ_HEAD(, req) reqhead;
85 /* a pending request */
86 struct req {
87 	struct event		 ev;
88 	struct url		 url;
89 	uint32_t		 id;
90 	int			 fd;
91 	struct tls		*ctx;
92 	char			 buf[1024];
93 	size_t			 off;
94 	TAILQ_ENTRY(req)	 reqs;
95 };
96 
97 static inline void
98 yield_r(struct req *req, statefn fn, struct timeval *tv)
99 {
100 	event_once(req->fd, EV_READ, fn, req, tv);
101 }
102 
103 static inline void
104 yield_w(struct req *req, statefn fn, struct timeval *tv)
105 {
106 	event_once(req->fd, EV_WRITE, fn, req, tv);
107 }
108 
109 static inline void
110 advance_buf(struct req *req, size_t len)
111 {
112 	assert(len <= req->off);
113 
114 	req->off -= len;
115 	memmove(req->buf, req->buf + len, req->off);
116 }
117 
118 static void __attribute__((__noreturn__))
119 die(void)
120 {
121 	abort(); 		/* TODO */
122 }
123 
124 static char *
125 xasprintf(const char *fmt, ...)
126 {
127 	va_list ap;
128 	char *s;
129 
130 	va_start(ap, fmt);
131 	if (vasprintf(&s, fmt, ap) == -1)
132 		s = NULL;
133 	va_end(ap);
134 
135 	return s;
136 }
137 
138 static int
139 conn_towards(struct url *url, char **err)
140 {
141 	struct addrinfo	 hints, *servinfo, *p;
142 	int		 status, sock;
143 	const char	*proto = "1965";
144 
145 	*err = NULL;
146 
147 	if (*url->port != '\0')
148 		proto = url->port;
149 
150 	memset(&hints, 0, sizeof(hints));
151 	hints.ai_family = AF_UNSPEC;
152 	hints.ai_socktype = SOCK_STREAM;
153 
154 	if ((status = getaddrinfo(url->host, proto, &hints, &servinfo))) {
155 		*err = xasprintf("failed to resolve %s: %s",
156 		    url->host, gai_strerror(status));
157 		return -1;
158 	}
159 
160 	sock = -1;
161 	for (p = servinfo; p != NULL; p = p->ai_next) {
162 		if ((sock = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1)
163 			continue;
164 		if (connect(sock, p->ai_addr, p->ai_addrlen) != -1)
165 			break;
166 		close(sock);
167 	}
168 
169 	if (sock == -1)
170 		*err = xasprintf("couldn't connect to %s", url->host);
171 	else
172 		mark_nonblock(sock);
173 
174 	freeaddrinfo(servinfo);
175 	return sock;
176 }
177 
178 static struct req *
179 req_by_id(uint32_t id)
180 {
181 	struct req *r;
182 
183 	if ((r = req_by_id_try(id)) == NULL)
184 		die();
185 	return r;
186 }
187 
188 static struct req *
189 req_by_id_try(uint32_t id)
190 {
191 	struct req *r;
192 
193 	TAILQ_FOREACH(r, &reqhead, reqs) {
194 		if (r->id == id)
195 			return r;
196 	}
197 
198 	return NULL;
199 }
200 
201 static void
202 close_conn(int fd, short ev, void *d)
203 {
204 	struct req	*req = d;
205 
206 	if (req->ctx != NULL) {
207 		switch (tls_close(req->ctx)) {
208 		case TLS_WANT_POLLIN:
209 			yield_r(req, close_conn, NULL);
210 			return;
211 		case TLS_WANT_POLLOUT:
212 			yield_w(req, close_conn, NULL);
213 			return;
214 		}
215 
216 		tls_free(req->ctx);
217 	}
218 
219 	TAILQ_REMOVE(&reqhead, req, reqs);
220 	if (req->fd != -1)
221 		close(req->fd);
222 	free(req);
223 }
224 
225 static void
226 close_with_err(struct req *req, const char *err)
227 {
228 	imsg_compose(ibuf, IMSG_ERR, req->id, 0, -1, err, strlen(err)+1);
229 	imsg_flush(ibuf);
230 	close_conn(0, 0, req);
231 }
232 
233 static void
234 close_with_errf(struct req *req, const char *fmt, ...)
235 {
236 	va_list	 ap;
237 	char	*s;
238 
239 	va_start(ap, fmt);
240 	if (vasprintf(&s, fmt, ap) == -1)
241 		abort();
242 	va_end(ap);
243 
244 	close_with_err(req, s);
245 	free(s);
246 }
247 
248 static void
249 do_handshake(int fd, short ev, void *d)
250 {
251 	struct req	*req = d;
252 	const char	*hash;
253 	char		*e;
254 
255 	if (ev == EV_TIMEOUT) {
256 		close_with_err(req, "Timeout loading page");
257 		return;
258 	}
259 
260 	switch (tls_handshake(req->ctx)) {
261 	case TLS_WANT_POLLIN:
262 		yield_r(req, do_handshake, NULL);
263 		return;
264 	case TLS_WANT_POLLOUT:
265 		yield_w(req, do_handshake, NULL);
266 		return;
267 	}
268 
269 	hash = tls_peer_cert_hash(req->ctx);
270 	if (hash == NULL) {
271 		close_with_errf(req, "handshake failed: %s", tls_error(req->ctx));
272 		return;
273 	}
274 	imsg_compose(ibuf, IMSG_CHECK_CERT, req->id, 0, -1, hash, strlen(hash)+1);
275 	imsg_flush(ibuf);
276 }
277 
278 static void
279 write_request(int fd, short ev, void *d)
280 {
281 	struct req	*req = d;
282 	ssize_t		 r;
283 	size_t		 len;
284 	char		 buf[1024];
285 
286 	strlcpy(buf, "gemini://", sizeof(buf));
287 	strlcat(buf, req->url.host, sizeof(buf));
288 	strlcat(buf, "/", sizeof(buf));
289 	strlcat(buf, req->url.path, sizeof(buf));
290 
291 	if (req->url.query[0] != '\0') {
292 		strlcat(buf, "?", sizeof(buf));
293 		strlcat(buf, req->url.query, sizeof(buf));
294 	}
295 
296 	len = strlcat(buf, "\r\n", sizeof(buf));
297 
298 	assert(len <= sizeof(buf));
299 
300 	switch (r = tls_write(req->ctx, buf, len)) {
301 	case -1:
302 		close_with_errf(req, "tls_write: %s", tls_error(req->ctx));
303 		break;
304 	case TLS_WANT_POLLIN:
305 		yield_r(req, write_request, NULL);
306 		break;
307 	case TLS_WANT_POLLOUT:
308 		yield_w(req, write_request, NULL);
309 		break;
310 	default:
311 		/* assume r == len */
312 		(void)r;
313 		yield_r(req, read_reply, NULL);
314 		break;
315 	}
316 }
317 
318 static void
319 read_reply(int fd, short ev, void *d)
320 {
321 	struct req	*req = d;
322 	size_t		 len;
323 	ssize_t		 r;
324 	char		*buf;
325 
326 	buf = req->buf + req->off;
327 	len = sizeof(req->buf) - req->off;
328 
329 	switch (r = tls_read(req->ctx, buf, len)) {
330 	case -1:
331 		close_with_errf(req, "tls_read: %s", tls_error(req->ctx));
332 		break;
333 	case TLS_WANT_POLLIN:
334 		yield_r(req, read_reply, NULL);
335 		break;
336 	case TLS_WANT_POLLOUT:
337 		yield_w(req, read_reply, NULL);
338 		break;
339 	default:
340 		req->off += r;
341 
342 		/* TODO: really watch for \r\n not \n alone */
343 		if (telescope_strnchr(req->buf, '\n', req->off) != NULL)
344 			parse_reply(req);
345 		else if (req->off == sizeof(req->buf))
346 			close_with_err(req, "invalid response");
347 		else
348 			yield_r(req, read_reply, NULL);
349 		break;
350 	}
351 }
352 
353 static void
354 parse_reply(struct req *req)
355 {
356 	int	 code;
357 	char	*e;
358 	size_t	 len;
359 
360 	if (req->off < 4)
361 		goto err;
362 
363 	if (!isdigit(req->buf[0]) || !isdigit(req->buf[1]))
364 		goto err;
365 
366 	code = (req->buf[0] - '0')*10 + (req->buf[1] - '0');
367 
368 	if (!isspace(req->buf[2]))
369 		goto err;
370 
371 	advance_buf(req, 3);
372 	if ((e = telescope_strnchr(req->buf, '\r', req->off)) == NULL)
373 		goto err;
374 
375 	*e = '\0';
376 	e++;
377 	len = e - req->buf;
378 	imsg_compose(ibuf, IMSG_GOT_CODE, req->id, 0, -1, &code, sizeof(code));
379 	imsg_compose(ibuf, IMSG_GOT_META, req->id, 0, -1,
380 	    req->buf, len);
381 	imsg_flush(ibuf);
382 
383 	if (code != 20)
384 		close_conn(0, 0, req);
385 	advance_buf(req, len+1); /* skip \n too */
386 
387 	return;
388 
389 err:
390 	close_with_err(req, "malformed request");
391 }
392 
393 static void
394 copy_body(int fd, short ev, void *d)
395 {
396 	struct req	*req = d;
397 	ssize_t		 r;
398 
399 	for (;;) {
400 		if (req->off != 0) {
401 			imsg_compose(ibuf, IMSG_BUF, req->id, 0, -1,
402 			    req->buf, req->off);
403 			imsg_flush(ibuf);
404 			req->off = 0;
405 		}
406 
407 		switch (r = tls_read(req->ctx, req->buf, sizeof(req->buf))) {
408 		case TLS_WANT_POLLIN:
409 			yield_r(req, copy_body, NULL);
410 			return;
411 		case TLS_WANT_POLLOUT:
412 			yield_w(req, copy_body, NULL);
413 			return;
414 		case 0:
415 			imsg_compose(ibuf, IMSG_EOF, req->id, 0, -1, NULL, 0);
416 			imsg_flush(ibuf);
417 			close_conn(0, 0, req);
418 			return;
419 		default:
420 			req->off = r;
421 		}
422 	}
423 }
424 
425 static void
426 handle_get(struct imsg *imsg, size_t datalen)
427 {
428 	struct req	*req;
429 	const char	*e;
430 	char		*data, *err = NULL;
431 
432 	data = imsg->data;
433 
434 	if (data[datalen-1] != '\0')
435 		die();
436 
437 	if ((req = calloc(1, sizeof(*req))) == NULL)
438 		die();
439 
440 	req->id = imsg->hdr.peerid;
441 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
442 
443         if (!url_parse(imsg->data, &req->url, &e)) {
444 		close_with_err(req, e);
445 		return;
446 	}
447 
448 	if ((req->fd = conn_towards(&req->url, &err)) == -1)
449 		goto err;
450 	if ((req->ctx = tls_client()) == NULL)
451 		goto err;
452 	if (tls_configure(req->ctx, tlsconf) == -1) {
453 		err = xasprintf("tls_configure: %s", tls_error(req->ctx));
454 		goto err;
455 	}
456 	if (tls_connect_socket(req->ctx, req->fd, req->url.host) == -1) {
457 		err = xasprintf("tls_connect_socket: %s", tls_error(req->ctx));
458 		goto err;
459 	}
460 
461 	yield_w(req, do_handshake, &timeout_for_handshake);
462 	return;
463 
464 err:
465         close_with_err(req, err);
466 	free(err);
467 }
468 
469 static void
470 handle_cert_status(struct imsg *imsg, size_t datalen)
471 {
472 	struct req	*req;
473 	int		 is_ok;
474 
475 	req = req_by_id(imsg->hdr.peerid);
476 
477 	if (datalen < sizeof(is_ok))
478 		die();
479 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
480 
481 	if (is_ok)
482 		yield_w(req, write_request, NULL);
483 	else
484 		close_conn(0, 0, req);
485 }
486 
487 static void
488 handle_proceed(struct imsg *imsg, size_t datalen)
489 {
490 	yield_r(req_by_id(imsg->hdr.peerid),
491 	    copy_body, NULL);
492 }
493 
494 static void
495 handle_stop(struct imsg *imsg, size_t datalen)
496 {
497 	struct req	*req;
498 
499 	if ((req = req_by_id_try(imsg->hdr.peerid)) == NULL)
500 		return;
501 	close_conn(0, 0, req);
502 }
503 
504 static void
505 handle_quit(struct imsg *imsg, size_t datalen)
506 {
507 	event_loopbreak();
508 }
509 
510 static void
511 handle_dispatch_imsg(int fd, short ev, void *d)
512 {
513 	struct imsgbuf	*ibuf = d;
514 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
515 }
516 
517 int
518 client_main(struct imsgbuf *b)
519 {
520 	ibuf = b;
521 
522 	TAILQ_INIT(&reqhead);
523 
524 	if ((tlsconf = tls_config_new()) == NULL)
525 		die();
526 	tls_config_insecure_noverifycert(tlsconf);
527 
528 	event_init();
529 
530 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
531 	event_add(&imsgev, NULL);
532 
533 	sandbox_network_process();
534 
535 	event_dispatch();
536 	return 0;
537 }