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 static void		 try_to_connect(int, short, void*);
56 
57 #if HAVE_ASR_RUN
58 static void		 query_done(struct asr_result*, void*);
59 static void		 async_conn_towards(struct req*);
60 #else
61 static void 		 blocking_conn_towards(struct req*);
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_raw(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_RAW]		= handle_get_raw,
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 phos_uri		 url;
101 	uint32_t		 id;
102 	int			 fd;
103 	struct tls		*ctx;
104 	char			 buf[1024];
105 	size_t			 off;
106 
107 	struct addrinfo		*servinfo, *p;
108 #if HAVE_ASR_RUN
109 	struct addrinfo		 hints;
110 	struct event_asr	*asrev;
111 #endif
112 
113 	TAILQ_ENTRY(req)	 reqs;
114 };
115 
116 static inline void
117 yield_r(struct req *req, statefn fn, struct timeval *tv)
118 {
119 	event_once(req->fd, EV_READ, fn, req, tv);
120 }
121 
122 static inline void
123 yield_w(struct req *req, statefn fn, struct timeval *tv)
124 {
125 	event_once(req->fd, EV_WRITE, fn, req, tv);
126 }
127 
128 static inline void
129 advance_buf(struct req *req, size_t len)
130 {
131 	assert(len <= req->off);
132 
133 	req->off -= len;
134 	memmove(req->buf, req->buf + len, req->off);
135 }
136 
137 static void __attribute__((__noreturn__))
138 die(void)
139 {
140 	abort(); 		/* TODO */
141 }
142 
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 again:
151 	if (req->p == NULL)
152 		goto err;
153 
154 	if (req->fd != -1) {
155 		if (getsockopt(req->fd, SOL_SOCKET, SO_ERROR, &error, &len) == -1)
156 			goto err;
157 		if (error != 0) {
158                         errno = error;
159                         goto err;
160 		}
161 		goto done;
162 	}
163 
164 	req->fd = socket(req->p->ai_family, req->p->ai_socktype, req->p->ai_protocol);
165 	if (req->fd == -1) {
166 		req->p = req->p->ai_next;
167 		goto again;
168 	} else {
169 		mark_nonblock(req->fd);
170 		if (connect(req->fd, req->p->ai_addr, req->p->ai_addrlen) == 0)
171 			goto done;
172 		yield_w(req, try_to_connect, NULL);
173 	}
174 	return;
175 
176 err:
177 	freeaddrinfo(req->servinfo);
178 	close_with_errf(req, "failed to connect to %s",
179 	    req->url.host);
180 	return;
181 
182 done:
183 	freeaddrinfo(req->servinfo);
184 	setup_tls(req);
185 }
186 
187 #if HAVE_ASR_RUN
188 static void
189 query_done(struct asr_result *res, void *d)
190 {
191 	struct req	*req = d;
192 
193 	req->asrev = NULL;
194 	if (res->ar_gai_errno != 0) {
195 		close_with_errf(req, "failed to resolve %s: %s",
196 		    req->url.host, gai_strerror(res->ar_gai_errno));
197 		return;
198 	}
199 
200 	req->fd = -1;
201 	req->servinfo = res->ar_addrinfo;
202 	req->p = res->ar_addrinfo;
203 	try_to_connect(0, 0, req);
204 }
205 
206 static void
207 async_conn_towards(struct req *req)
208 {
209 	struct asr_query	*q;
210 	const char		*proto = "1965";
211 
212 	if (*req->url.port != '\0')
213 		proto = req->url.port;
214 
215 	req->hints.ai_family = AF_UNSPEC;
216 	req->hints.ai_socktype = SOCK_STREAM;
217 	q = getaddrinfo_async(req->url.host, proto, &req->hints, NULL);
218 	req->asrev = event_asr_run(q, query_done, req);
219 }
220 #else
221 static void
222 blocking_conn_towards(struct req *req)
223 {
224 	struct addrinfo	 hints;
225 	struct phos_uri	*url = &req->url;
226 	int		 status;
227 	const char	*proto = "1965";
228 
229 	if (*url->port != '\0')
230 		proto = url->port;
231 
232 	memset(&hints, 0, sizeof(hints));
233 	hints.ai_family = AF_UNSPEC;
234 	hints.ai_socktype = SOCK_STREAM;
235 
236 	if ((status = getaddrinfo(url->host, proto, &hints, &req->servinfo))) {
237 		close_with_errf(req, "failed to resolve %s: %s",
238 		    url->host, gai_strerror(status));
239 		return;
240 	}
241 
242 	req->fd = -1;
243 	req->p = req->servinfo;
244 	try_to_connect(0, 0, req);
245 }
246 #endif
247 
248 static struct req *
249 req_by_id(uint32_t id)
250 {
251 	struct req *r;
252 
253 	if ((r = req_by_id_try(id)) == NULL)
254 		die();
255 	return r;
256 }
257 
258 static struct req *
259 req_by_id_try(uint32_t id)
260 {
261 	struct req *r;
262 
263 	TAILQ_FOREACH(r, &reqhead, reqs) {
264 		if (r->id == id)
265 			return r;
266 	}
267 
268 	return NULL;
269 }
270 
271 static void
272 close_conn(int fd, short ev, void *d)
273 {
274 	struct req	*req = d;
275 
276 #if HAVE_ASR_RUN
277 	if (req->asrev != NULL)
278 		event_asr_abort(req->asrev);
279 #endif
280 
281 	if (req->ctx != NULL) {
282 		switch (tls_close(req->ctx)) {
283 		case TLS_WANT_POLLIN:
284 			yield_r(req, close_conn, NULL);
285 			return;
286 		case TLS_WANT_POLLOUT:
287 			yield_w(req, close_conn, NULL);
288 			return;
289 		}
290 
291 		tls_free(req->ctx);
292 	}
293 
294 	TAILQ_REMOVE(&reqhead, req, reqs);
295 	if (req->fd != -1)
296 		close(req->fd);
297 	free(req);
298 }
299 
300 static void
301 close_with_err(struct req *req, const char *err)
302 {
303 	imsg_compose(ibuf, IMSG_ERR, req->id, 0, -1, err, strlen(err)+1);
304 	imsg_flush(ibuf);
305 	close_conn(0, 0, req);
306 }
307 
308 static void
309 close_with_errf(struct req *req, const char *fmt, ...)
310 {
311 	va_list	 ap;
312 	char	*s;
313 
314 	va_start(ap, fmt);
315 	if (vasprintf(&s, fmt, ap) == -1)
316 		abort();
317 	va_end(ap);
318 
319 	close_with_err(req, s);
320 	free(s);
321 }
322 
323 static void
324 setup_tls(struct req *req)
325 {
326 	if ((req->ctx = tls_client()) == NULL) {
327 		close_with_errf(req, "tls_client: %s", strerror(errno));
328 		return;
329 	}
330 	if (tls_configure(req->ctx, tlsconf) == -1) {
331 		close_with_errf(req, "tls_configure: %s", tls_error(req->ctx));
332 		return;
333 	}
334 	if (tls_connect_socket(req->ctx, req->fd, req->url.host) == -1) {
335 		close_with_errf(req, "tls_connect_socket: %s", tls_error(req->ctx));
336 		return;
337 	}
338 	yield_w(req, do_handshake, &timeout_for_handshake);
339 }
340 
341 static void
342 do_handshake(int fd, short ev, void *d)
343 {
344 	struct req	*req = d;
345 	const char	*hash;
346 
347 	if (ev == EV_TIMEOUT) {
348 		close_with_err(req, "Timeout loading page");
349 		return;
350 	}
351 
352 	switch (tls_handshake(req->ctx)) {
353 	case TLS_WANT_POLLIN:
354 		yield_r(req, do_handshake, NULL);
355 		return;
356 	case TLS_WANT_POLLOUT:
357 		yield_w(req, do_handshake, NULL);
358 		return;
359 	}
360 
361 	hash = tls_peer_cert_hash(req->ctx);
362 	if (hash == NULL) {
363 		close_with_errf(req, "handshake failed: %s", tls_error(req->ctx));
364 		return;
365 	}
366 	imsg_compose(ibuf, IMSG_CHECK_CERT, req->id, 0, -1, hash, strlen(hash)+1);
367 	imsg_flush(ibuf);
368 }
369 
370 static void
371 write_request(int fd, short ev, void *d)
372 {
373 	struct req	*req = d;
374 	ssize_t		 r;
375 	size_t		 len;
376 
377 	len = strlen(req->buf);
378 
379 	switch (r = tls_write(req->ctx, req->buf, len)) {
380 	case -1:
381 		close_with_errf(req, "tls_write: %s", tls_error(req->ctx));
382 		break;
383 	case TLS_WANT_POLLIN:
384 		yield_r(req, write_request, NULL);
385 		break;
386 	case TLS_WANT_POLLOUT:
387 		yield_w(req, write_request, NULL);
388 		break;
389 	default:
390 		/* assume r == len */
391 		(void)r;
392 		yield_r(req, read_reply, NULL);
393 		break;
394 	}
395 }
396 
397 static void
398 read_reply(int fd, short ev, void *d)
399 {
400 	struct req	*req = d;
401 	size_t		 len;
402 	ssize_t		 r;
403 	char		*buf;
404 
405 	buf = req->buf + req->off;
406 	len = sizeof(req->buf) - req->off;
407 
408 	switch (r = tls_read(req->ctx, buf, len)) {
409 	case -1:
410 		close_with_errf(req, "tls_read: %s", tls_error(req->ctx));
411 		break;
412 	case TLS_WANT_POLLIN:
413 		yield_r(req, read_reply, NULL);
414 		break;
415 	case TLS_WANT_POLLOUT:
416 		yield_w(req, read_reply, NULL);
417 		break;
418 	default:
419 		req->off += r;
420 
421 		if (memmem(req->buf, req->off, "\r\n", 2) != NULL)
422 			parse_reply(req);
423 		else if (req->off == sizeof(req->buf))
424 			close_with_err(req, "invalid response");
425 		else
426 			yield_r(req, read_reply, NULL);
427 		break;
428 	}
429 }
430 
431 static void
432 parse_reply(struct req *req)
433 {
434 	int	 code;
435 	char	*e;
436 	size_t	 len;
437 
438 	if (req->off < 4)
439 		goto err;
440 
441 	if (!isdigit(req->buf[0]) || !isdigit(req->buf[1]))
442 		goto err;
443 
444 	code = (req->buf[0] - '0')*10 + (req->buf[1] - '0');
445 
446 	if (!isspace(req->buf[2]))
447 		goto err;
448 
449 	advance_buf(req, 3);
450 	if ((e = memmem(req->buf, req->off, "\r\n", 2)) == NULL)
451 		goto err;
452 
453 	*e = '\0';
454 	e++;
455 	len = e - req->buf;
456 	imsg_compose(ibuf, IMSG_GOT_CODE, req->id, 0, -1, &code, sizeof(code));
457 	imsg_compose(ibuf, IMSG_GOT_META, req->id, 0, -1, req->buf, len);
458 	imsg_flush(ibuf);
459 
460 	if (20 <= code && code < 30)
461 		advance_buf(req, len+1); /* skip \n too */
462 	else
463 		close_conn(0, 0, req);
464 
465 	return;
466 
467 err:
468 	close_with_err(req, "malformed request");
469 }
470 
471 static void
472 copy_body(int fd, short ev, void *d)
473 {
474 	struct req	*req = d;
475 	ssize_t		 r;
476 
477 	for (;;) {
478 		if (req->off != 0) {
479 			imsg_compose(ibuf, IMSG_BUF, req->id, 0, -1,
480 			    req->buf, req->off);
481 			imsg_flush(ibuf);
482 			req->off = 0;
483 		}
484 
485 		switch (r = tls_read(req->ctx, req->buf, sizeof(req->buf))) {
486 		case TLS_WANT_POLLIN:
487 			yield_r(req, copy_body, NULL);
488 			return;
489 		case TLS_WANT_POLLOUT:
490 			yield_w(req, copy_body, NULL);
491 			return;
492 		case 0:
493 			imsg_compose(ibuf, IMSG_EOF, req->id, 0, -1, NULL, 0);
494 			imsg_flush(ibuf);
495 			close_conn(0, 0, req);
496 			return;
497 		default:
498 			req->off = r;
499 		}
500 	}
501 }
502 
503 static void
504 handle_get_raw(struct imsg *imsg, size_t datalen)
505 {
506 	struct req	*req;
507 	struct get_req	*r;
508 
509 	r = imsg->data;
510 
511 	if (datalen != sizeof(*r))
512 		die();
513 
514 	if ((req = calloc(1, sizeof(*req))) == NULL)
515 		die();
516 
517 	req->id = imsg->hdr.peerid;
518 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
519 
520 	strlcpy(req->url.host, r->host, sizeof(req->url.host));
521 	strlcpy(req->url.port, r->port, sizeof(req->url.port));
522 	strlcpy(req->buf, r->req, sizeof(req->buf));
523 
524 #if HAVE_ASR_RUN
525         async_conn_towards(req);
526 #else
527 	blocking_conn_towards(req);
528 #endif
529 }
530 
531 static void
532 handle_cert_status(struct imsg *imsg, size_t datalen)
533 {
534 	struct req	*req;
535 	int		 is_ok;
536 
537 	req = req_by_id(imsg->hdr.peerid);
538 
539 	if (datalen < sizeof(is_ok))
540 		die();
541 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
542 
543 	if (is_ok)
544 		yield_w(req, write_request, NULL);
545 	else
546 		close_conn(0, 0, req);
547 }
548 
549 static void
550 handle_proceed(struct imsg *imsg, size_t datalen)
551 {
552 	yield_r(req_by_id(imsg->hdr.peerid),
553 	    copy_body, NULL);
554 }
555 
556 static void
557 handle_stop(struct imsg *imsg, size_t datalen)
558 {
559 	struct req	*req;
560 
561 	if ((req = req_by_id_try(imsg->hdr.peerid)) == NULL)
562 		return;
563 	close_conn(0, 0, req);
564 }
565 
566 static void
567 handle_quit(struct imsg *imsg, size_t datalen)
568 {
569 	event_loopbreak();
570 }
571 
572 static void
573 handle_dispatch_imsg(int fd, short ev, void *d)
574 {
575 	struct imsgbuf	*ibuf = d;
576 	dispatch_imsg(ibuf, handlers, sizeof(handlers));
577 }
578 
579 int
580 client_main(struct imsgbuf *b)
581 {
582 	ibuf = b;
583 
584 	TAILQ_INIT(&reqhead);
585 
586 	if ((tlsconf = tls_config_new()) == NULL)
587 		die();
588 	tls_config_insecure_noverifycert(tlsconf);
589 	tls_config_insecure_noverifyname(tlsconf);
590 
591 	event_init();
592 
593 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, handle_dispatch_imsg, ibuf);
594 	event_add(&imsgev, NULL);
595 
596 	sandbox_network_process();
597 
598 	event_dispatch();
599 	return 0;
600 }