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Date:: Sun Jul 25 11:06:51 2021 UTC
Message:: initial gopher support
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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 	ssize_t			 ret;
382 	size_t			 len;
383 
384 	if (event == EV_TIMEOUT) {
385 		what |= EVBUFFER_TIMEOUT;
386 		goto err;
387 	}
388 
389 	if (bufev->wm_read.high != 0)
390 		howmuch = MIN(sizeof(buf), bufev->wm_read.high);
391 
392 	switch (ret = tls_read(req->ctx, buf, howmuch)) {
393 	case TLS_WANT_POLLIN:
394 	case TLS_WANT_POLLOUT:
395 		goto retry;
396 	case -1:
397 		what |= EVBUFFER_ERROR;
398 		goto err;
399 	}
400 	len = ret;
401 
402 	if (len == 0) {
403 		what |= EVBUFFER_EOF;
404 		goto err;
405 	}
406 
407 	if (evbuffer_add(bufev->input, buf, len) == -1) {
408 		what |= EVBUFFER_ERROR;
409 		goto err;
410 	}
411 
412 	event_add(&bufev->ev_read, NULL);
413 
414 	len = EVBUFFER_LENGTH(bufev->input);
415 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
416 		return;
417 
418 	if (bufev->readcb != NULL)
419 		(*bufev->readcb)(bufev, bufev->cbarg);
420 	return;
421 
422 retry:
423 	event_add(&bufev->ev_read, NULL);
424 	return;
425 
426 err:
427 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
428 }
429 
430 static void
431 net_tls_writecb(int fd, short event, void *d)
432 {
433 	struct bufferevent	*bufev = d;
434 	struct req		*req = bufev->cbarg;
435 	ssize_t			 ret;
436 	size_t			 len;
437 	short			 what = EVBUFFER_WRITE;
438 
439 	if (event & EV_TIMEOUT) {
440 		what |= EVBUFFER_TIMEOUT;
441 		goto err;
442 	}
443 
444 	if (EVBUFFER_LENGTH(bufev->output) != 0) {
445 		ret = tls_write(req->ctx, EVBUFFER_DATA(bufev->output),
446 		    EVBUFFER_LENGTH(bufev->output));
447 		switch (ret) {
448 		case TLS_WANT_POLLIN:
449 		case TLS_WANT_POLLOUT:
450 			goto retry;
451 		case -1:
452 			what |= EVBUFFER_ERROR;
453 			goto err;
454 		}
455 		len = ret;
456 		evbuffer_drain(bufev->output, len);
457 	}
458 
459 	if (EVBUFFER_LENGTH(bufev->output) != 0)
460 		event_add(&bufev->ev_write, NULL);
461 
462 	if (bufev->writecb != NULL &&
463 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
464 		(*bufev->writecb)(bufev, bufev->cbarg);
465 	return;
466 
467 retry:
468 	event_add(&bufev->ev_write, NULL);
469 	return;
470 
471 err:
472 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
473 }
474 
475 static int
476 gemini_parse_reply(struct req *req, const char *header, size_t len)
477 {
478 	int		 code;
479 	const char	*t;
480 
481 	if (len < 4)
482 		return 0;
483 
484 	if (!isdigit(header[0]) || !isdigit(header[1]))
485 		return 0;
486 
487 	code = (header[0] - '0')*10 + (header[1] - '0');
488 	if (header[2] != ' ')
489 		return 0;
490 
491 	t = header + 3;
492 
493 	net_send_ui(IMSG_GOT_CODE, req->id, &code, sizeof(code));
494 	net_send_ui(IMSG_GOT_META, req->id, t, strlen(t)+1);
495 
496 	bufferevent_disable(req->bev, EV_READ|EV_WRITE);
497 
498 	if (code < 20 || code >= 30)
499 		close_conn(0, 0, req);
500 	return 1;
501 }
502 
503 /* called when we're ready to read/write */
504 static void
505 net_ready(struct req *req)
506 {
507 	req->bev = bufferevent_new(req->fd, net_read, net_write, net_error,
508 	    req);
509 	if (req->bev == NULL)
510 		die();
511 
512 	/* setup tls i/o layer */
513 	if (req->ctx != NULL) {
514 		event_set(&req->bev->ev_read, req->fd, EV_READ,
515 		    net_tls_readcb, req->bev);
516 		event_set(&req->bev->ev_write, req->fd, EV_WRITE,
517 		    net_tls_writecb, req->bev);
518 	}
519 
520 	/* TODO: adjust watermarks */
521 	bufferevent_setwatermark(req->bev, EV_WRITE, 1, 0);
522 	bufferevent_setwatermark(req->bev, EV_READ,  1, 0);
523 
524 	bufferevent_enable(req->bev, EV_READ|EV_WRITE);
525 
526 	bufferevent_write(req->bev, req->req, req->len);
527 }
528 
529 /* called after a read has been done */
530 static void
531 net_read(struct bufferevent *bev, void *d)
532 {
533 	struct req	*req = d;
534 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
535 	void		*data;
536 	size_t		 len;
537 	int		 r;
538 	char		*header;
539 
540 	if (!req->done_header) {
541 		header = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
542 		if (header == NULL && EVBUFFER_LENGTH(src) >= 1024)
543 			goto err;
544 		if (header == NULL)
545 			return;
546 		r = gemini_parse_reply(req, header, len);
547 		free(header);
548 		if (!r)
549 			goto err;
550 		req->done_header = 1;
551 		return;
552 	}
553 
554 	if ((len = EVBUFFER_LENGTH(src)) == 0)
555 		return;
556 	data = EVBUFFER_DATA(src);
557 	net_send_ui(IMSG_BUF, req->id, data, len);
558 	evbuffer_drain(src, len);
559 	return;
560 
561 err:
562 	(*bev->errorcb)(bev, EVBUFFER_READ, bev->cbarg);
563 }
564 
565 /* called after a write has been done */
566 static void
567 net_write(struct bufferevent *bev, void *d)
568 {
569 	struct evbuffer	*dst = EVBUFFER_OUTPUT(bev);
570 
571 	if (EVBUFFER_LENGTH(dst) == 0)
572 		(*bev->errorcb)(bev, EVBUFFER_WRITE, bev->cbarg);
573 }
574 
575 static void
576 net_error(struct bufferevent *bev, short error, void *d)
577 {
578 	struct req	*req = d;
579 
580 	if (error & EVBUFFER_TIMEOUT) {
581 		close_with_err(req, "Timeout loading page");
582 		return;
583 	}
584 
585 	if (error & EVBUFFER_ERROR) {
586 		close_with_err(req, "buffer event error");
587 		return;
588 	}
589 
590 	if (error & EVBUFFER_EOF) {
591 		net_send_ui(IMSG_EOF, req->id, NULL, 0);
592 		close_conn(0, 0, req);
593 		return;
594 	}
595 
596 	if (error & EVBUFFER_WRITE) {
597 		/* finished sending request */
598 		bufferevent_disable(bev, EV_WRITE);
599 		return;
600 	}
601 
602 	if (error & EVBUFFER_READ) {
603 		close_with_err(req, "protocol error");
604 		return;
605 	}
606 
607 	close_with_errf(req, "unknown event error %x", error);
608 }
609 
610 static void
611 handle_get_raw(struct imsg *imsg, size_t datalen)
612 {
613 	struct req	*req;
614 	struct get_req	*r;
615 
616 	r = imsg->data;
617 
618 	if (datalen != sizeof(*r))
619 		die();
620 
621 	if ((req = calloc(1, sizeof(*req))) == NULL)
622 		die();
623 
624 	req->id = imsg->hdr.peerid;
625 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
626 
627 	strlcpy(req->url.host, r->host, sizeof(req->url.host));
628 	strlcpy(req->url.port, r->port, sizeof(req->url.port));
629 
630 	strlcpy(req->req, r->req, sizeof(req->req));
631 	req->len = strlen(r->req);
632 
633 	req->proto = r->proto;
634 
635 #if HAVE_ASR_RUN
636         async_conn_towards(req);
637 #else
638 	blocking_conn_towards(req);
639 #endif
640 }
641 
642 static void
643 handle_cert_status(struct imsg *imsg, size_t datalen)
644 {
645 	struct req	*req;
646 	int		 is_ok;
647 
648 	req = req_by_id(imsg->hdr.peerid);
649 
650 	if (datalen < sizeof(is_ok))
651 		die();
652 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
653 
654 	if (is_ok)
655 		net_ready(req);
656 	else
657 		close_conn(0, 0, req);
658 }
659 
660 static void
661 handle_proceed(struct imsg *imsg, size_t datalen)
662 {
663 	struct req *req;
664 
665 	if ((req = req_by_id(imsg->hdr.peerid)) == NULL)
666 		return;
667 
668 	bufferevent_enable(req->bev, EV_READ);
669 }
670 
671 static void
672 handle_stop(struct imsg *imsg, size_t datalen)
673 {
674 	struct req	*req;
675 
676 	if ((req = req_by_id(imsg->hdr.peerid)) == NULL)
677 		return;
678 	close_conn(0, 0, req);
679 }
680 
681 static void
682 handle_quit(struct imsg *imsg, size_t datalen)
683 {
684 	event_loopbreak();
685 }
686 
687 static void
688 handle_dispatch_imsg(int fd, short ev, void *d)
689 {
690 	struct imsgev	*iev = d;
691 
692 	if (dispatch_imsg(iev, ev, handlers, sizeof(handlers)) == -1)
693 		err(1, "connection closed");
694 }
695 
696 static int
697 net_send_ui(int type, uint32_t peerid, const void *data,
698     uint16_t datalen)
699 {
700 	return imsg_compose_event(iev_ui, type, peerid, 0, -1,
701 	    data, datalen);
702 }
703 
704 int
705 net_main(void)
706 {
707 	setproctitle("net");
708 
709 	TAILQ_INIT(&reqhead);
710 
711 	if ((tlsconf = tls_config_new()) == NULL)
712 		die();
713 	tls_config_insecure_noverifycert(tlsconf);
714 	tls_config_insecure_noverifyname(tlsconf);
715 
716 	event_init();
717 
718 	/* Setup pipe and event handler to the main process */
719 	if ((iev_ui = malloc(sizeof(*iev_ui))) == NULL)
720 		die();
721 	imsg_init(&iev_ui->ibuf, 3);
722 	iev_ui->handler = handle_dispatch_imsg;
723 	iev_ui->events = EV_READ;
724 	event_set(&iev_ui->ev, iev_ui->ibuf.fd, iev_ui->events,
725 	    iev_ui->handler, iev_ui);
726 	event_add(&iev_ui->ev, NULL);
727 
728 	sandbox_net_process();
729 
730 	event_dispatch();
731 
732 	tls_config_free(tlsconf);
733 	msgbuf_clear(&iev_ui->ibuf.w);
734 	close(iev_ui->ibuf.fd);
735 	free(iev_ui);
736 
737 	return 0;
738 }