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Date:: Tue Mar 2 16:32:07 2021 UTC
Message:: move special page to main process
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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 /*
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 <event.h>
36 #include <netdb.h>
37 #include <stdarg.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <tls.h>
42 #include <unistd.h>
43 
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 *err);
54 static struct req	*req_by_id(uint32_t);
55 
56 static void		 do_handshake(int, short, void*);
57 static void		 write_request(int, short, void*);
58 static void		 read_reply(int, short, void*);
59 static void		 parse_reply(struct req*);
60 static void		 copy_body(int, short, void*);
61 
62 static void		 check_special_page(struct req*, const char*);
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 
70 static imsg_handlerfn *handlers[] = {
71 	[IMSG_GET] = handle_get,
72 	[IMSG_CERT_STATUS] = handle_cert_status,
73 	[IMSG_PROCEED] = handle_proceed,
74 	[IMSG_STOP] = handle_stop,
75 	[IMSG_QUIT] = handle_quit,
76 };
77 
78 typedef void (*statefn)(int, short, void*);
79 
80 TAILQ_HEAD(, req) reqhead;
81 /* a pending request */
82 struct req {
83 	struct event		 ev;
84 	struct url		 url;
85 	uint32_t		 id;
86 	int			 fd;
87 	struct tls		*ctx;
88 	char			 buf[1024];
89 	size_t			 off;
90 	TAILQ_ENTRY(req)	 reqs;
91 };
92 
93 static inline void
94 yield_r(struct req *req, statefn fn, struct timeval *tv)
95 {
96 	event_once(req->fd, EV_READ, fn, req, tv);
97 }
98 
99 static inline void
100 yield_w(struct req *req, statefn fn, struct timeval *tv)
101 {
102 	event_once(req->fd, EV_WRITE, fn, req, tv);
103 }
104 
105 static inline void
106 advance_buf(struct req *req, size_t len)
107 {
108 	assert(len <= req->off);
109 
110 	req->off -= len;
111 	memmove(req->buf, req->buf + len, req->off);
112 }
113 
114 static void __attribute__((__noreturn__))
115 die(void)
116 {
117 	abort(); 		/* TODO */
118 }
119 
120 static char *
121 xasprintf(const char *fmt, ...)
122 {
123 	va_list ap;
124 	char *s;
125 
126 	va_start(ap, fmt);
127 	if (vasprintf(&s, fmt, ap) == -1)
128 		s = NULL;
129 	va_end(ap);
130 
131 	return s;
132 }
133 
134 static int
135 conn_towards(struct url *url, char **err)
136 {
137 	struct addrinfo	 hints, *servinfo, *p;
138 	int		 status, sock;
139 	const char	*proto = "1965";
140 
141 	*err = NULL;
142 
143 	if (*url->port != '\0')
144 		proto = url->port;
145 
146 	memset(&hints, 0, sizeof(hints));
147 	hints.ai_family = AF_UNSPEC;
148 	hints.ai_socktype = SOCK_STREAM;
149 
150 	if ((status = getaddrinfo(url->host, proto, &hints, &servinfo))) {
151 		*err = xasprintf("failed to resolve %s: %s",
152 		    url->host, gai_strerror(status));
153 		return -1;
154 	}
155 
156 	sock = -1;
157 	for (p = servinfo; p != NULL; p = p->ai_next) {
158 		if ((sock = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1)
159 			continue;
160 		if (connect(sock, p->ai_addr, p->ai_addrlen) != -1)
161 			break;
162 		close(sock);
163 	}
164 
165 	if (sock == -1)
166 		*err = xasprintf("couldn't connect to %s", url->host);
167 	else
168 		mark_nonblock(sock);
169 
170 	freeaddrinfo(servinfo);
171 	return sock;
172 }
173 
174 static struct req *
175 req_by_id(uint32_t id)
176 {
177 	struct req *r;
178 
179 	TAILQ_FOREACH(r, &reqhead, reqs) {
180 		if (r->id == id)
181 			return r;
182 	}
183 
184 	die();
185 }
186 
187 static void
188 close_conn(int fd, short ev, void *d)
189 {
190 	struct req	*req = d;
191 
192 	if (req->ctx != NULL) {
193 		switch (tls_close(req->ctx)) {
194 		case TLS_WANT_POLLIN:
195 			yield_r(req, close_conn, NULL);
196 			return;
197 		case TLS_WANT_POLLOUT:
198 			yield_w(req, close_conn, NULL);
199 			return;
200 		}
201 
202 		tls_free(req->ctx);
203 	}
204 
205 	TAILQ_REMOVE(&reqhead, req, reqs);
206 	if (req->fd != -1)
207 		close(req->fd);
208 	free(req);
209 }
210 
211 static void
212 close_with_err(struct req *req, const char *err)
213 {
214 	imsg_compose(ibuf, IMSG_ERR, req->id, 0, -1, err, strlen(err)+1);
215 	imsg_flush(ibuf);
216 	close_conn(0, 0, req);
217 }
218 
219 static void
220 do_handshake(int fd, short ev, void *d)
221 {
222 	struct req	*req = d;
223 	const char	*hash;
224 
225 	switch (tls_handshake(req->ctx)) {
226 	case TLS_WANT_POLLIN:
227 		yield_r(req, do_handshake, NULL);
228 		return;
229 	case TLS_WANT_POLLOUT:
230 		yield_w(req, do_handshake, NULL);
231 		return;
232 	}
233 
234 	hash = tls_peer_cert_hash(req->ctx);
235 	imsg_compose(ibuf, IMSG_CHECK_CERT, req->id, 0, -1, hash, strlen(hash)+1);
236 	imsg_flush(ibuf);
237 }
238 
239 static void
240 write_request(int fd, short ev, void *d)
241 {
242 	struct req	*req = d;
243 	ssize_t		 r;
244 	size_t		 len;
245 	char		 buf[1024], *err;
246 
247 	strlcpy(buf, "gemini://", sizeof(buf));
248 	strlcat(buf, req->url.host, sizeof(buf));
249 	strlcat(buf, "/", sizeof(buf));
250 	strlcat(buf, req->url.path, sizeof(buf));
251 
252 	if (req->url.query[0] != '\0') {
253 		strlcat(buf, "?", sizeof(buf));
254 		strlcat(buf, req->url.query, sizeof(buf));
255 	}
256 
257 	len = strlcat(buf, "\r\n", sizeof(buf));
258 
259 	assert(len <= sizeof(buf));
260 
261 	switch (r = tls_write(req->ctx, buf, len)) {
262 	case -1:
263 		err = xasprintf("tls_write: %s", tls_error(req->ctx));
264 		close_with_err(req, err);
265 		free(err);
266 		break;
267 	case TLS_WANT_POLLIN:
268 		yield_r(req, write_request, NULL);
269 		break;
270 	case TLS_WANT_POLLOUT:
271 		yield_w(req, write_request, NULL);
272 		break;
273 	default:
274 		/* assume r == len */
275 		(void)r;
276 		yield_r(req, read_reply, NULL);
277 		break;
278 	}
279 }
280 
281 static void
282 read_reply(int fd, short ev, void *d)
283 {
284 	struct req	*req = d;
285 	size_t		 len;
286 	ssize_t		 r;
287 	char		*buf, *e;
288 
289 	buf = req->buf + req->off;
290 	len = sizeof(req->buf) - req->off;
291 
292 	switch (r = tls_read(req->ctx, buf, len)) {
293 	case -1:
294 		e = xasprintf("tls_read: %s", tls_error(req->ctx));
295 		close_with_err(req, e);
296 		free(e);
297 		break;
298 	case TLS_WANT_POLLIN:
299 		yield_r(req, read_reply, NULL);
300 		break;
301 	case TLS_WANT_POLLOUT:
302 		yield_w(req, read_reply, NULL);
303 		break;
304 	default:
305 		req->off += r;
306 
307 		/* TODO: really watch for \r\n not \n alone */
308 		if ((e = telescope_strnchr(req->buf, '\n', req->off)) != NULL)
309 			parse_reply(req);
310 		else if (req->off == sizeof(req->buf))
311 			close_with_err(req, "invalid response");
312 		else
313 			yield_r(req, read_reply, NULL);
314 		break;
315 	}
316 }
317 
318 static void
319 parse_reply(struct req *req)
320 {
321 	int	 code;
322 	char	*e;
323 	size_t	 len;
324 
325 	if (req->off < 4)
326 		goto err;
327 
328 	if (!isdigit(req->buf[0]) || !isdigit(req->buf[1]))
329 		goto err;
330 
331 	code = (req->buf[0] - '0')*10 + (req->buf[1] - '0');
332 
333 	if (!isspace(req->buf[2]))
334 		goto err;
335 
336 	advance_buf(req, 3);
337 	if ((e = telescope_strnchr(req->buf, '\r', req->off)) == NULL)
338 		goto err;
339 
340 	*e = '\0';
341 	e++;
342 	len = e - req->buf;
343 	imsg_compose(ibuf, IMSG_GOT_CODE, req->id, 0, -1, &code, sizeof(code));
344 	imsg_compose(ibuf, IMSG_GOT_META, req->id, 0, -1,
345 	    req->buf, len);
346 	imsg_flush(ibuf);
347 
348 	return;
349 
350 err:
351 	close_with_err(req, "malformed request");
352 }
353 
354 static void
355 copy_body(int fd, short ev, void *d)
356 {
357 	struct req	*req = d;
358 	char		 buf[BUFSIZ];
359 	ssize_t		 r;
360 
361 	for (;;) {
362 		switch (r = tls_read(req->ctx, buf, sizeof(buf))) {
363 		case TLS_WANT_POLLIN:
364 			yield_r(req, copy_body, NULL);
365 			return;
366 		case TLS_WANT_POLLOUT:
367 			yield_w(req, copy_body, NULL);
368 			return;
369 		case -1:
370 		case 0:
371 			imsg_compose(ibuf, IMSG_EOF, req->id, 0, -1, NULL, 0);
372 			imsg_flush(ibuf);
373 			close_conn(0, 0, req);
374 			return;
375 		default:
376 			imsg_compose(ibuf, IMSG_BUF, req->id, 0, -1, buf, r);
377 			imsg_flush(ibuf);
378 			break;
379 		}
380 	}
381 }
382 
383 static void
384 handle_get(struct imsg *imsg, size_t datalen)
385 {
386 	struct req	*req;
387 	const char	*e;
388 	char		*data, *err = NULL;
389 
390 	data = imsg->data;
391 
392 	if (data[datalen-1] != '\0')
393 		die();
394 
395 	if ((req = calloc(1, sizeof(*req))) == NULL)
396 		die();
397 
398 	req->id = imsg->hdr.peerid;
399 
400         if (!url_parse(imsg->data, &req->url, &e)) {
401 		fprintf(stderr, "failed to parse url: %s\n", e);
402 		close_with_err(req, e);
403 		return;
404 	}
405 
406 	if ((req->fd = conn_towards(&req->url, &err)) == -1)
407 		goto err;
408 	if ((req->ctx = tls_client()) == NULL)
409 		goto err;
410 	if (tls_configure(req->ctx, tlsconf) == -1) {
411 		err = xasprintf("tls_configure: %s", tls_error(req->ctx));
412 		goto err;
413 	}
414 	if (tls_connect_socket(req->ctx, req->fd, req->url.host) == -1) {
415 		err = xasprintf("tls_connect_socket: %s", tls_error(req->ctx));
416 		goto err;
417 	}
418 
419 	TAILQ_INSERT_HEAD(&reqhead, req, reqs);
420 	yield_w(req, do_handshake, NULL);
421 	return;
422 
423 err:
424         close_with_err(req, err);
425 	free(err);
426 }
427 
428 static void
429 handle_cert_status(struct imsg *imsg, size_t datalen)
430 {
431 	struct req	*req;
432 	int		 is_ok;
433 
434 	req = req_by_id(imsg->hdr.peerid);
435 
436 	if (datalen < sizeof(is_ok))
437 		die();
438 	memcpy(&is_ok, imsg->data, sizeof(is_ok));
439 
440 	if (is_ok)
441 		yield_w(req, write_request, NULL);
442 	else
443 		close_conn(0, 0, req);
444 }
445 
446 static void
447 handle_proceed(struct imsg *imsg, size_t datalen)
448 {
449 	struct req	*req;
450 
451 	req = req_by_id(imsg->hdr.peerid);
452 	yield_r(req, copy_body, NULL);
453 }
454 
455 static void
456 handle_stop(struct imsg *imsg, size_t datalen)
457 {
458 	struct req	*req;
459 
460 	req = req_by_id(imsg->hdr.peerid);
461 	close_conn(0, 0, req);
462 }
463 
464 static void
465 handle_quit(struct imsg *imsg, size_t datalen)
466 {
467 	event_loopbreak();
468 }
469 
470 static void
471 dispatch_imsg(int fd, short ev, void *d)
472 {
473 	struct imsgbuf	*ibuf = d;
474 	struct imsg	 imsg;
475 	ssize_t		 n;
476 	size_t		 datalen;
477 
478 	if ((n = imsg_read(ibuf)) == -1) {
479 		if (errno == EAGAIN || errno == EWOULDBLOCK)
480 			return;
481 		die();
482 	}
483 
484 	if (n == 0)
485 		die();
486 
487 	for (;;) {
488 		if ((n = imsg_get(ibuf, &imsg)) == -1)
489 			die();
490 		if (n == 0)
491 			return;
492 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
493 		handlers[imsg.hdr.type](&imsg, datalen);
494 		imsg_free(&imsg);
495 	}
496 }
497 
498 int
499 client_main(struct imsgbuf *b)
500 {
501 	ibuf = b;
502 
503 	TAILQ_INIT(&reqhead);
504 
505 	if ((tlsconf = tls_config_new()) == NULL)
506 		die();
507 	tls_config_insecure_noverifycert(tlsconf);
508 
509 	event_init();
510 
511 	event_set(&imsgev, ibuf->fd, EV_READ | EV_PERSIST, dispatch_imsg, ibuf);
512 	event_add(&imsgev, NULL);
513 
514 	event_dispatch();
515 	return 0;
516 }