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Date:: Tue Jul 27 21:01:54 2021 UTC
Message:: buffer is frozen; drain becomes a NOP
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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 #include "compat.h"
18 
19 #include <sys/types.h>
20 #include <sys/socket.h>
21 
22 #include <netinet/in.h>
23 
24 #include <assert.h>
25 #include <ctype.h>
26 #include <errno.h>
27 #include <netdb.h>
28 #include <stdarg.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <tls.h>
33 #include <unistd.h>
34 
35 #if HAVE_ASR_RUN
36 # include <asr.h>
37 #endif
38 
39 #include "telescope.h"
40 
41 static struct imsgev		*iev_ui;
42 static struct tls_config	*tlsconf;
43 
44 /* a pending request */
45 struct req {
46 	struct phos_uri		 url;
47 	uint32_t		 id;
48 	int			 proto;
49 	int			 fd;
50 	struct tls		*ctx;
51 	char			 req[1024];
52 	size_t			 len;
53 	int			 done_header;
54 	struct bufferevent	*bev;
55 
56 	struct addrinfo		*servinfo, *p;
57 #if HAVE_ASR_RUN
58 	struct addrinfo		 hints;
59 	struct event_asr	*asrev;
60 #endif
61 
62 	TAILQ_ENTRY(req)	 reqs;
63 };
64 
65 static struct req	*req_by_id(uint32_t);
66 
67 static void	 die(void) __attribute__((__noreturn__));
68 
69 static void	 try_to_connect(int, short, void*);
70 
71 #if HAVE_ASR_RUN
72 static void	 query_done(struct asr_result*, void*);
73 static void	 async_conn_towards(struct req*);
74 #else
75 static void	 blocking_conn_towards(struct req*);
76 #endif
77 
78 static void	 close_with_err(struct req*, const char*);
79 static void	 close_with_errf(struct req*, const char*, ...)
80     __attribute__((format(printf, 2, 3)));
81 
82 static void	 net_tls_handshake(int, short, void *);
83 static void	 net_tls_readcb(int, short, void *);
84 static void	 net_tls_writecb(int, short, void *);
85 
86 static int	 gemini_parse_reply(struct req *, const char *, size_t);
87 
88 static void	 net_ready(struct req *req);
89 static void	 net_read(struct bufferevent *, void *);
90 static void	 net_write(struct bufferevent *, void *);
91 static void	 net_error(struct bufferevent *, short, void *);
92 
93 static void	 handle_get_raw(struct imsg *, size_t);
94 static void	 handle_cert_status(struct imsg*, size_t);
95 static void	 handle_proceed(struct imsg*, size_t);
96 static void	 handle_stop(struct imsg*, size_t);
97 static void	 handle_quit(struct imsg*, size_t);
98 static void	 handle_dispatch_imsg(int, short, void*);
99 
100 static int	 net_send_ui(int, uint32_t, const void *, uint16_t);
101 
102 /* TODO: making this customizable */
103 struct timeval timeout_for_handshake = { 5, 0 };
104 
105 static imsg_handlerfn *handlers[] = {
106 	[IMSG_GET_RAW]		= handle_get_raw,
107 	[IMSG_CERT_STATUS]	= handle_cert_status,
108 	[IMSG_PROCEED]		= handle_proceed,
109 	[IMSG_STOP]		= handle_stop,
110 	[IMSG_QUIT]		= handle_quit,
111 };
112 
113 typedef void (*statefn)(int, short, void*);
114 
115 TAILQ_HEAD(, req) reqhead;
116 
117 static inline void
118 yield_r(struct req *req, statefn fn, struct timeval *tv)
119 {
120 	event_once(req->fd, EV_READ, fn, req, tv);
121 }
122 
123 static inline void
124 yield_w(struct req *req, statefn fn, struct timeval *tv)
125 {
126 	event_once(req->fd, EV_WRITE, fn, req, tv);
127 }
128 
129 static struct req *
130 req_by_id(uint32_t id)
131 {
132 	struct req *r;
133 
134 	TAILQ_FOREACH(r, &reqhead, reqs) {
135 		if (r->id == id)
136 			return r;
137 	}
138 
139 	return NULL;
140 }
141 
142 static void __attribute__((__noreturn__))
143 die(void)
144 {
145 	abort(); 		/* TODO */
146 }
147 
148 static void
149 try_to_connect(int fd, short ev, void *d)
150 {
151 	struct req	*req = d;
152 	int		 error = 0;
153 	socklen_t	 len = sizeof(error);
154 
155 again:
156 	if (req->p == NULL)
157 		goto err;
158 
159 	if (req->fd != -1) {
160 		if (getsockopt(req->fd, SOL_SOCKET, SO_ERROR, &error,
161 		    &len) == -1)
162 			goto err;
163 		if (error != 0) {
164                         errno = error;
165                         goto err;
166 		}
167 		goto done;
168 	}
169 
170 	req->fd = socket(req->p->ai_family, req->p->ai_socktype,
171 	    req->p->ai_protocol);
172 	if (req->fd == -1) {
173 		req->p = req->p->ai_next;
174 		goto again;
175 	} else {
176 		mark_nonblock(req->fd);
177 		if (connect(req->fd, req->p->ai_addr, req->p->ai_addrlen) == 0)
178 			goto done;
179 		yield_w(req, try_to_connect, NULL);
180 	}
181 	return;
182 
183 err:
184 	freeaddrinfo(req->servinfo);
185 	close_with_errf(req, "failed to connect to %s",
186 	    req->url.host);
187 	return;
188 
189 done:
190 	freeaddrinfo(req->servinfo);
191 
192 	switch (req->proto) {
193 	case PROTO_FINGER:
194 	case PROTO_GOPHER:
195 		/* finger and gopher don't have a header nor TLS */
196 		req->done_header = 1;
197 		net_ready(req);
198 		break;
199 
200 	case PROTO_GEMINI:
201 		/* prepare tls */
202 		if ((req->ctx = tls_client()) == NULL) {
203 			close_with_errf(req, "tls_client: %s",
204 			    strerror(errno));
205 			return;
206 		}
207 		if (tls_configure(req->ctx, tlsconf) == -1) {
208 			close_with_errf(req, "tls_configure: %s",
209 			    tls_error(req->ctx));
210 			return;
211 		}
212 		if (tls_connect_socket(req->ctx, req->fd, req->url.host)
213 		    == -1) {
214 			close_with_errf(req, "tls_connect_socket: %s",
215 			    tls_error(req->ctx));
216 			return;
217 		}
218 		yield_w(req, net_tls_handshake, &timeout_for_handshake);
219 		break;
220 
221 	default:
222 		die();
223 	}
224 }
225 
226 #if HAVE_ASR_RUN
227 static void
228 query_done(struct asr_result *res, void *d)
229 {
230 	struct req	*req = d;
231 
232 	req->asrev = NULL;
233 	if (res->ar_gai_errno != 0) {
234 		close_with_errf(req, "failed to resolve %s: %s",
235 		    req->url.host, gai_strerror(res->ar_gai_errno));
236 		return;
237 	}
238 
239 	req->fd = -1;
240 	req->servinfo = res->ar_addrinfo;
241 	req->p = res->ar_addrinfo;
242 	try_to_connect(0, 0, req);
243 }
244 
245 static void
246 async_conn_towards(struct req *req)
247 {
248 	struct asr_query	*q;
249 	const char		*proto = "1965";
250 
251 	if (*req->url.port != '\0')
252 		proto = req->url.port;
253 
254 	req->hints.ai_family = AF_UNSPEC;
255 	req->hints.ai_socktype = SOCK_STREAM;
256 	q = getaddrinfo_async(req->url.host, proto, &req->hints, NULL);
257 	req->asrev = event_asr_run(q, query_done, req);
258 }
259 #else
260 static void
261 blocking_conn_towards(struct req *req)
262 {
263 	struct addrinfo	 hints;
264 	struct phos_uri	*url = &req->url;
265 	int		 status;
266 	const char	*proto = "1965";
267 
268 	if (*url->port != '\0')
269 		proto = url->port;
270 
271 	memset(&hints, 0, sizeof(hints));
272 	hints.ai_family = AF_UNSPEC;
273 	hints.ai_socktype = SOCK_STREAM;
274 
275 	if ((status = getaddrinfo(url->host, proto, &hints, &req->servinfo))) {
276 		close_with_errf(req, "failed to resolve %s: %s",
277 		    url->host, gai_strerror(status));
278 		return;
279 	}
280 
281 	req->fd = -1;
282 	req->p = req->servinfo;
283 	try_to_connect(0, 0, req);
284 }
285 #endif
286 
287 static void
288 close_conn(int fd, short ev, void *d)
289 {
290 	struct req	*req = d;
291 
292 #if HAVE_ASR_RUN
293 	if (req->asrev != NULL)
294 		event_asr_abort(req->asrev);
295 #endif
296 
297 	if (req->bev != NULL) {
298 		bufferevent_free(req->bev);
299 		req->bev = NULL;
300 	}
301 
302 	if (req->ctx != NULL) {
303 		switch (tls_close(req->ctx)) {
304 		case TLS_WANT_POLLIN:
305 			yield_r(req, close_conn, NULL);
306 			return;
307 		case TLS_WANT_POLLOUT:
308 			yield_w(req, close_conn, NULL);
309 			return;
310 		}
311 
312 		tls_free(req->ctx);
313 		req->ctx = NULL;
314 	}
315 
316 	TAILQ_REMOVE(&reqhead, req, reqs);
317 	if (req->fd != -1)
318 		close(req->fd);
319 	free(req);
320 }
321 
322 static void
323 close_with_err(struct req *req, const char *err)
324 {
325 	net_send_ui(IMSG_ERR, req->id, err, strlen(err)+1);
326 	close_conn(0, 0, req);
327 }
328 
329 static void
330 close_with_errf(struct req *req, const char *fmt, ...)
331 {
332 	va_list	 ap;
333 	char	*s;
334 
335 	va_start(ap, fmt);
336 	if (vasprintf(&s, fmt, ap) == -1)
337 		abort();
338 	va_end(ap);
339 
340 	close_with_err(req, s);
341 	free(s);
342 }
343 
344 static void
345 net_tls_handshake(int fd, short event, void *d)
346 {
347 	struct req	*req = d;
348 	const char	*hash;
349 
350 	if (event == EV_TIMEOUT) {
351 		close_with_err(req, "Timeout loading page");
352 		return;
353 	}
354 
355 	switch (tls_handshake(req->ctx)) {
356 	case TLS_WANT_POLLIN:
357 		yield_r(req, net_tls_handshake, NULL);
358 		return;
359 	case TLS_WANT_POLLOUT:
360 		yield_w(req, net_tls_handshake, NULL);
361 		return;
362 	}
363 
364 	hash = tls_peer_cert_hash(req->ctx);
365 	if (hash == NULL) {
366 		close_with_errf(req, "handshake failed: %s",
367 		    tls_error(req->ctx));
368 		return;
369 	}
370 	net_send_ui(IMSG_CHECK_CERT, req->id, hash, strlen(hash)+1);
371 }
372 
373 static void
374 net_tls_readcb(int fd, short event, void *d)
375 {
376 	struct bufferevent	*bufev = d;
377 	struct req		*req = bufev->cbarg;
378 	char			 buf[IBUF_READ_SIZE];
379 	int			 what = EVBUFFER_READ;
380 	int			 howmuch = IBUF_READ_SIZE;
381 	int			 res;
382 	ssize_t			 ret;
383 	size_t			 len;
384 
385 	if (event == EV_TIMEOUT) {
386 		what |= EVBUFFER_TIMEOUT;
387 		goto err;
388 	}
389 
390 	if (bufev->wm_read.high != 0)
391 		howmuch = MIN(sizeof(buf), bufev->wm_read.high);
392 
393 	switch (ret = tls_read(req->ctx, buf, howmuch)) {
394 	case TLS_WANT_POLLIN:
395 	case TLS_WANT_POLLOUT:
396 		goto retry;
397 	case -1:
398 		what |= EVBUFFER_ERROR;
399 		goto err;
400 	}
401 	len = ret;
402 
403 	if (len == 0) {
404 		what |= EVBUFFER_EOF;
405 		goto err;
406 	}
407 
408 	evbuffer_unfreeze(bufev->input, 0);
409 	res = evbuffer_add(bufev->input, buf, len);
410 	evbuffer_freeze(bufev->input, 0);
411 	if (res == -1) {
412 		what |= EVBUFFER_ERROR;
413 		goto err;
414 	}
415 
416 	event_add(&bufev->ev_read, NULL);
417 
418 	len = EVBUFFER_LENGTH(bufev->input);
419 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
420 		return;
421 
422 	if (bufev->readcb != NULL)
423 		(*bufev->readcb)(bufev, bufev->cbarg);
424 	return;
425 
426 retry:
427 	event_add(&bufev->ev_read, NULL);
428 	return;
429 
430 err:
431 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
432 }
433 
434 static void
435 net_tls_writecb(int fd, short event, void *d)
436 {
437 	struct bufferevent	*bufev = d;
438 	struct req		*req = bufev->cbarg;
439 	ssize_t			 ret;
440 	size_t			 len;
441 	short			 what = EVBUFFER_WRITE;
442 
443 	if (event & EV_TIMEOUT) {
444 		what |= EVBUFFER_TIMEOUT;
445 		goto err;
446 	}
447 
448 	if (EVBUFFER_LENGTH(bufev->output) != 0) {
449 		ret = tls_write(req->ctx, EVBUFFER_DATA(bufev->output),
450 		    EVBUFFER_LENGTH(bufev->output));
451 		switch (ret) {
452 		case TLS_WANT_POLLIN:
453 		case TLS_WANT_POLLOUT:
454 			goto retry;
455 		case -1:
456 			what |= EVBUFFER_ERROR;
457 			goto err;
458 		}
459 		len = ret;
460 
461 		evbuffer_unfreeze(bufev->output, 1);
462 		evbuffer_drain(bufev->output, len);
463 		evbuffer_freeze(bufev->output, 1);
464 	}
465 
466 	if (EVBUFFER_LENGTH(bufev->output) != 0)
467 		event_add(&bufev->ev_write, NULL);
468 
469 	if (bufev->writecb != NULL &&
470 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
471 		(*bufev->writecb)(bufev, bufev->cbarg);
472 	return;
473 
474 retry:
475 	event_add(&bufev->ev_write, NULL);
476 	return;
477 
478 err:
479 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
480 }
481 
482 static int
483 gemini_parse_reply(struct req *req, const char *header, size_t len)
484 {
485 	int		 code;
486 	const char	*t;
487 
488 	if (len < 4)
489 		return 0;
490 
491 	if (!isdigit(header[0]) || !isdigit(header[1]))
492 		return 0;
493 
494 	code = (header[0] - '0')*10 + (header[1] - '0');
495 	if (header[2] != ' ')
496 		return 0;
497 
498 	t = header + 3;
499 
500 	net_send_ui(IMSG_GOT_CODE, req->id, &code, sizeof(code));
501 	net_send_ui(IMSG_GOT_META, req->id, t, strlen(t)+1);
502 
503 	bufferevent_disable(req->bev, EV_READ|EV_WRITE);
504 
505 	if (code < 20 || code >= 30)
506 		close_conn(0, 0, req);
507 	return 1;
508 }
509 
510 /* called when we're ready to read/write */
511 static void
512 net_ready(struct req *req)
513 {
514 	req->bev = bufferevent_new(req->fd, net_read, net_write, net_error,
515 	    req);
516 	if (req->bev == NULL)
517 		die();
518 
519 	/* setup tls i/o layer */
520 	if (req->ctx != NULL) {
521 		event_set(&req->bev->ev_read, req->fd, EV_READ,
522 		    net_tls_readcb, req->bev);
523 		event_set(&req->bev->ev_write, req->fd, EV_WRITE,
524 		    net_tls_writecb, req->bev);
525 	}
526 
527 	/* TODO: adjust watermarks */
528 	bufferevent_setwatermark(req->bev, EV_WRITE, 1, 0);
529 	bufferevent_setwatermark(req->bev, EV_READ,  1, 0);
530 
531 	bufferevent_enable(req->bev, EV_READ|EV_WRITE);
532 
533 	bufferevent_write(req->bev, req->req, req->len);
534 }
535 
536 /* called after a read has been done */
537 static void
538 net_read(struct bufferevent *bev, void *d)
539 {
540 	struct req	*req = d;
541 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
542 	void		*data;
543 	size_t		 len;
544 	int		 r;
545 	char		*header;
546 
547 	if (!req->done_header) {
548 		header = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
549 		if (header == NULL && EVBUFFER_LENGTH(src) >= 1024)
550 			goto err;
551 		if (header == NULL)
552 			return;
553 		r = gemini_parse_reply(req, header, len);
554 		free(header);
555 		if (!r)
556 			goto err;
557 		req->done_header = 1;
558 		return;
559 	}
560 
561 	if ((len = EVBUFFER_LENGTH(src)) == 0)
562 		return;
563 	data = EVBUFFER_DATA(src);
564 	net_send_ui(IMSG_BUF, req->id, data, len);
565 	evbuffer_drain(src, len);
566 	return;
567 
568 err:
569 	(*bev->errorcb)(bev, EVBUFFER_READ, bev->cbarg);
570 }
571 
572 /* called after a write has been done */
573 static void
574 net_write(struct bufferevent *bev, void *d)
575 {
576 	struct evbuffer	*dst = EVBUFFER_OUTPUT(bev);
577 
578 	if (EVBUFFER_LENGTH(dst) == 0)
579 		(*bev->errorcb)(bev, EVBUFFER_WRITE, bev->cbarg);
580 }
581 
582 static void
583 net_error(struct bufferevent *bev, short error, void *d)
584 {
585 	struct req	*req = d;
586 	struct evbuffer	*src;
587 
588 	if (error & EVBUFFER_TIMEOUT) {
589 		close_with_err(req, "Timeout loading page");
590 		return;
591 	}
592 
593 	if (error & EVBUFFER_ERROR) {
594 		close_with_err(req, "buffer event error");
595 		return;
596 	}
597 
598 	if (error & EVBUFFER_EOF) {
599                 src = EVBUFFER_INPUT(req->bev);
600 		if (EVBUFFER_LENGTH(src) != 0)
601 			net_send_ui(IMSG_BUF, req->id, EVBUFFER_DATA(src),
602 			    EVBUFFER_LENGTH(src));
603 		net_send_ui(IMSG_EOF, req->id, NULL, 0);
604 		close_conn(0, 0, req);
605 		return;
606 	}
607 
608 	if (error & EVBUFFER_WRITE) {
609 		/* finished sending request */
610 		bufferevent_disable(bev, EV_WRITE);
611 		return;
612 	}
613 
614 	if (error & EVBUFFER_READ) {
615 		close_with_err(req, "protocol error");
616 		return;
617 	}
618 
619 	close_with_errf(req, "unknown event error %x", error);
620 }
621 
622 static void
623 handle_get_raw(struct imsg *imsg, size_t datalen)
624 {
625 	struct req	*req;
626 	struct get_req	*r;
627 
628 	r = imsg->data;
629 
630 	if (datalen != sizeof(*r))
631 		die();
632 
633 	if ((req = calloc(1, sizeof(*req))) == NULL)
634 		die();
635 
636 	req->id = imsg->hdr.peerid;
637 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
638 
639 	strlcpy(req->url.host, r->host, sizeof(req->url.host));
640 	strlcpy(req->url.port, r->port, sizeof(req->url.port));
641 
642 	strlcpy(req->req, r->req, sizeof(req->req));
643 	req->len = strlen(r->req);
644 
645 	req->proto = r->proto;
646 
647 #if HAVE_ASR_RUN
648         async_conn_towards(req);
649 #else
650 	blocking_conn_towards(req);
651 #endif
652 }
653 
654 static void
655 handle_cert_status(struct imsg *imsg, size_t datalen)
656 {
657 	struct req	*req;
658 	int		 is_ok;
659 
660 	req = req_by_id(imsg->hdr.peerid);
661 
662 	if (datalen < sizeof(is_ok))
663 		die();
664 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
665 
666 	if (is_ok)
667 		net_ready(req);
668 	else
669 		close_conn(0, 0, req);
670 }
671 
672 static void
673 handle_proceed(struct imsg *imsg, size_t datalen)
674 {
675 	struct req *req;
676 
677 	if ((req = req_by_id(imsg->hdr.peerid)) == NULL)
678 		return;
679 
680 	bufferevent_enable(req->bev, EV_READ);
681 }
682 
683 static void
684 handle_stop(struct imsg *imsg, size_t datalen)
685 {
686 	struct req	*req;
687 
688 	if ((req = req_by_id(imsg->hdr.peerid)) == NULL)
689 		return;
690 	close_conn(0, 0, req);
691 }
692 
693 static void
694 handle_quit(struct imsg *imsg, size_t datalen)
695 {
696 	event_loopbreak();
697 }
698 
699 static void
700 handle_dispatch_imsg(int fd, short ev, void *d)
701 {
702 	struct imsgev	*iev = d;
703 
704 	if (dispatch_imsg(iev, ev, handlers, sizeof(handlers)) == -1)
705 		err(1, "connection closed");
706 }
707 
708 static int
709 net_send_ui(int type, uint32_t peerid, const void *data,
710     uint16_t datalen)
711 {
712 	return imsg_compose_event(iev_ui, type, peerid, 0, -1,
713 	    data, datalen);
714 }
715 
716 int
717 net_main(void)
718 {
719 	setproctitle("net");
720 
721 	TAILQ_INIT(&reqhead);
722 
723 	if ((tlsconf = tls_config_new()) == NULL)
724 		die();
725 	tls_config_insecure_noverifycert(tlsconf);
726 	tls_config_insecure_noverifyname(tlsconf);
727 
728 	event_init();
729 
730 	/* Setup pipe and event handler to the main process */
731 	if ((iev_ui = malloc(sizeof(*iev_ui))) == NULL)
732 		die();
733 	imsg_init(&iev_ui->ibuf, 3);
734 	iev_ui->handler = handle_dispatch_imsg;
735 	iev_ui->events = EV_READ;
736 	event_set(&iev_ui->ev, iev_ui->ibuf.fd, iev_ui->events,
737 	    iev_ui->handler, iev_ui);
738 	event_add(&iev_ui->ev, NULL);
739 
740 	sandbox_net_process();
741 
742 	event_dispatch();
743 
744 	tls_config_free(tlsconf);
745 	msgbuf_clear(&iev_ui->ibuf.w);
746 	close(iev_ui->ibuf.fd);
747 	free(iev_ui);
748 
749 	return 0;
750 }