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Date:: Wed Sep 14 18:26:48 2022 UTC
Message:: refactor proxy_read - avoid the ugly `goto copy' to jump back to the start - avoid leaking memory
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1 /*
2  * Copyright (c) 2022 Omar Polo <op@omarpolo.com>
3  * Copyright (c) 2006 - 2015 Reyk Floeter <reyk@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/queue.h>
20 #include <sys/tree.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23 
24 #include <netinet/in.h>
25 #include <arpa/inet.h>
26 #include <netdb.h>
27 
28 #include <asr.h>
29 #include <ctype.h>
30 #include <errno.h>
31 #include <event.h>
32 #include <fnmatch.h>
33 #include <limits.h>
34 #include <stdlib.h>
35 #include <stdint.h>
36 #include <stdio.h>
37 #include <string.h>
38 #include <imsg.h>
39 #include <tls.h>
40 #include <unistd.h>
41 
42 #include "log.h"
43 #include "proc.h"
44 
45 #include "galileo.h"
46 
47 #define MINIMUM(a, b)	((a) < (b) ? (a) : (b))
48 
49 /* provided by OpenBSD' base libevent but not in any header? */
50 extern void	 bufferevent_read_pressure_cb(struct evbuffer *, size_t,
51 		    size_t, void *);
52 
53 void	proxy_init(struct privsep *, struct privsep_proc *, void *);
54 int	proxy_launch(struct galileo *);
55 void	proxy_inflight_dec(const char *);
56 int	proxy_dispatch_parent(int, struct privsep_proc *, struct imsg *);
57 void	proxy_translate_gemtext(struct client *);
58 void	proxy_resolved(struct asr_result *, void *);
59 void	proxy_connect(int, short, void *);
60 void	proxy_read(struct bufferevent *, void *);
61 void	proxy_write(struct bufferevent *, void *);
62 void	proxy_error(struct bufferevent *, short, void *);
63 int	proxy_bufferevent_add(struct event *, int);
64 void	proxy_tls_writecb(int, short, void *);
65 void	proxy_tls_readcb(int, short, void *);
66 
67 static struct privsep_proc procs[] = {
68 	{ "parent",	PROC_PARENT, proxy_dispatch_parent },
69 };
70 
71 volatile int proxy_clients;
72 volatile int proxy_inflight;
73 uint32_t proxy_fcg_id;
74 
75 void
76 proxy(struct privsep *ps, struct privsep_proc *p)
77 {
78 	proc_run(ps, p, procs, nitems(procs), proxy_init, NULL);
79 }
80 
81 void
82 proxy_init(struct privsep *ps, struct privsep_proc *p, void *arg)
83 {
84 	if (config_init(ps->ps_env) == -1)
85 		fatal("failed to initialize configuration");
86 
87 	/* We use a custom shutdown callback */
88 	/* p->p_shutdown = proxy_shutdown */
89 
90 	if (pledge("stdio recvfd unix inet dns", NULL) == -1)
91 		fatal("pledge");
92 }
93 
94 int
95 proxy_launch(struct galileo *env)
96 {
97 	event_add(&env->sc_evsock, NULL);
98 	return (0);
99 }
100 
101 void
102 proxy_purge(struct server *srv)
103 {
104 }
105 
106 void
107 proxy_inflight_dec(const char *why)
108 {
109 	proxy_inflight--;
110 	log_debug("%s: inflight decremented, now %d, %s",
111 	    __func__, proxy_inflight, why);
112 }
113 
114 int
115 proxy_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
116 {
117 	struct privsep	*ps = p->p_ps;
118 	struct galileo	*env = ps->ps_env;
119 
120 	switch (imsg->hdr.type) {
121 	case IMSG_CFG_SRV:
122 		if (config_getserver(env, imsg) == -1)
123 			fatal("config_getproxy");
124 		break;
125 	case IMSG_CFG_SOCK:
126 		/* XXX: improve */
127 
128 		if (env->sc_sock_fd != -1) {
129 			event_del(&env->sc_evsock);
130 			close(env->sc_sock_fd);
131 		}
132 
133 		env->sc_sock_fd = config_getsock(env, imsg);
134 		if (env->sc_sock_fd == -1)
135 			fatal("config_getsock");
136 
137 		event_set(&env->sc_evsock, env->sc_sock_fd,
138 		    EV_READ | EV_PERSIST, fcgi_accept, env);
139 		event_add(&env->sc_evsock, NULL);
140 		evtimer_set(&env->sc_evpause, fcgi_accept, env);
141 		break;
142 	case IMSG_CFG_DONE:
143 		log_debug("config done!");
144 		break;
145 	case IMSG_CTL_START:
146 		proxy_launch(env);
147 		break;
148 	default:
149 		log_warnx("unknown message %d", imsg->hdr.type);
150 		return (-1);
151 	}
152 
153 	return (0);
154 }
155 
156 static inline int
157 printurl(struct client *clt, const char *str)
158 {
159 	for (; *str; ++str) {
160 		switch (*str) {
161 		case ' ':
162 		case '\t':
163 		case '\'':
164 		case '\\':
165 			if (clt_printf(clt, "%2X", (unsigned char)*str) == -1)
166 				return (-1);
167 			break;
168 		default:
169 			if (clt_putc(clt, *str) == -1)
170 				return (-1);
171 			break;
172 		}
173 	}
174 
175 	return (0);
176 }
177 
178 static inline int
179 htmlescape(struct client *clt, const char *str)
180 {
181 	int r;
182 
183 	for (; *str; ++str) {
184 		switch (*str) {
185 		case '<':
186 			r = clt_puts(clt, "&lt;");
187 			break;
188 		case '>':
189 			r = clt_puts(clt, "&gt;");
190 			break;
191 		case '&':
192 			r = clt_puts(clt, "&amp;");
193 			break;
194 		default:
195 			r = clt_putc(clt, *str);
196 			break;
197 		}
198 
199 		if (r == -1)
200 			return (-1);
201 	}
202 
203 	return (0);
204 }
205 
206 static int
207 gemtext_translate_line(struct client *clt, char *line)
208 {
209 	/* preformatted line / closing */
210 	if (clt->clt_translate & TR_PRE) {
211 		if (!strncmp(line, "```", 3)) {
212 			clt->clt_translate &= ~TR_PRE;
213 			return (clt_puts(clt, "</pre>"));
214 		}
215 
216 		if (htmlescape(clt, line) == -1)
217 			return (-1);
218 		return (clt_putc(clt, '\n'));
219 	}
220 
221 	/* bullet */
222 	if (!strncmp(line, "* ", 2)) {
223 		if (clt->clt_translate & TR_NAV) {
224 			if (clt_puts(clt, "</ul></nav>") == -1)
225 				return (-1);
226 			clt->clt_translate &= ~TR_NAV;
227 		}
228 
229 		if (!(clt->clt_translate & TR_LIST)) {
230 			if (clt_puts(clt, "<ul>") == -1)
231 				return (-1);
232 			clt->clt_translate |= TR_LIST;
233 		}
234 
235 		if (clt_puts(clt, "<li>") == -1 ||
236 		    htmlescape(clt, line + 2) == -1 ||
237 		    clt_puts(clt, "</li>") == -1)
238 			return (-1);
239 		return (0);
240 	}
241 
242 	if (clt->clt_translate & TR_LIST) {
243 		if (clt_puts(clt, "</ul>") == -1)
244 			return (-1);
245 		clt->clt_translate &= ~TR_LIST;
246 	}
247 
248 	/* link -- TODO: relativify from SCRIPT_NAME */
249 	if (!strncmp(line, "=>", 2)) {
250 		char *label;
251 
252 		line += 2;
253 		line += strspn(line, " \t");
254 
255 		label = line + strcspn(line, " \t");
256 		if (*label == '\0')
257 			label = line;
258 		else
259 			*label++ = '\0';
260 
261 		if (fnmatch("*.jpg", line, 0) == 0 ||
262 		    fnmatch("*.jpeg", line, 0) == 0 ||
263 		    fnmatch("*.gif", line, 0) == 0 ||
264 		    fnmatch("*.png", line, 0) == 0 ||
265 		    fnmatch("*.svg", line, 0) == 0 ||
266 		    fnmatch("*.webp", line, 0) == 0) {
267 			if (clt->clt_translate & TR_NAV) {
268 				if (clt_puts(clt, "</ul></nav>") == -1)
269 					return (-1);
270 				clt->clt_translate &= ~TR_NAV;
271 			}
272 
273 			if (clt_puts(clt, "<figure><a href='") == -1 ||
274 			    printurl(clt, line) == -1 ||
275 			    clt_puts(clt, "'><img src='") == -1 ||
276 			    printurl(clt, line) == -1 ||
277 			    clt_puts(clt, "' /></a><figcaption>") == -1 ||
278 			    htmlescape(clt, label) == -1 ||
279 			    clt_puts(clt, "</figcaption></figure>") == -1)
280 				return (-1);
281 
282 			return (0);
283 		}
284 
285 		if (!(clt->clt_translate & TR_NAV)) {
286 			if (clt_puts(clt, "<nav><ul>") == -1)
287 				return (-1);
288 			clt->clt_translate |= TR_NAV;
289 		}
290 
291 		if (clt_puts(clt, "<li><a href='") == -1 ||
292 		    printurl(clt, line) == -1 ||
293 		    clt_puts(clt, "'>") == -1 ||
294 		    htmlescape(clt, label) == -1 ||
295 		    clt_puts(clt, "</a></li>") == -1)
296 			return (-1);
297 
298 		return (0);
299 	}
300 
301 	if (clt->clt_translate & TR_NAV) {
302 		if (clt_puts(clt, "</ul></nav>") == -1)
303 			return (-1);
304 		clt->clt_translate &= ~TR_NAV;
305 	}
306 
307 	/* pre opening */
308 	if (!strncmp(line, "```", 3)) {
309 		clt->clt_translate |= TR_PRE;
310 		return (clt_puts(clt, "<pre>"));
311 	}
312 
313 	/* citation block */
314 	if (*line == '>') {
315 		if (clt_puts(clt, "<blockquote>") == -1 ||
316 		    htmlescape(clt, line + 1) == -1 ||
317 		    clt_puts(clt, "</blockquote>") == -1)
318 			return (-1);
319 		return (0);
320 	}
321 
322 	/* headings */
323 	if (!strncmp(line, "###", 3)) {
324 		if (clt_puts(clt, "<h3>") == -1 ||
325 		    htmlescape(clt, line + 3) == -1 ||
326 		    clt_puts(clt, "</h3>") == -1)
327 			return (-1);
328 		return (0);
329 	}
330 	if (!strncmp(line, "##", 2)) {
331 		if (clt_puts(clt, "<h2>") == -1 ||
332 		    htmlescape(clt, line + 2) == -1 ||
333 		    clt_puts(clt, "</h2>") == -1)
334 			return (-1);
335 		return (0);
336 	}
337 	if (!strncmp(line, "#", 1)) {
338 		if (clt_puts(clt, "<h1>") == -1 ||
339 		    htmlescape(clt, line + 1) == -1 ||
340 		    clt_puts(clt, "</h1>") == -1)
341 			return (-1);
342 		return (0);
343 	}
344 
345 	/* Not following strictly the gemini specification... */
346 	if (*line == '\0')
347 		return (0);
348 
349 	/* paragraph */
350 	if (clt_puts(clt, "<p>") == -1 ||
351 	    htmlescape(clt, line) == -1 ||
352 	    clt_puts(clt, "</p>") == -1)
353 		return (-1);
354 
355 	return (0);
356 }
357 
358 void
359 proxy_translate_gemtext(struct client *clt)
360 {
361 	struct bufferevent	*bev = clt->clt_bev;
362 	struct evbuffer		*src = EVBUFFER_INPUT(bev);
363 	char			*line;
364 	size_t			 len;
365 	int			 r;
366 
367 	for (;;) {
368 		line = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF);
369 		if (line == NULL)
370 			return;
371 
372 		r = gemtext_translate_line(clt, line);
373 		free(line);
374 		if (r == -1)
375 			return;
376 	}
377 }
378 
379 static struct proxy_config *
380 proxy_server_match(struct galileo *env, struct client *clt)
381 {
382 	struct server		*srv;
383 
384 	if (clt->clt_server_name == NULL)
385 		return NULL;
386 
387 	TAILQ_FOREACH(srv, &env->sc_servers, srv_entry) {
388 		if (!strcmp(clt->clt_server_name, srv->srv_conf.host))
389 			return &srv->srv_conf;
390 	}
391 
392 	return NULL;
393 }
394 
395 void
396 proxy_start_request(struct galileo *env, struct client *clt)
397 {
398 	struct addrinfo		 hints;
399 	struct asr_query	*query;
400 	char			 port[32];
401 
402 	if ((clt->clt_pc = proxy_server_match(env, clt)) == NULL) {
403 		if (clt_printf(clt, "Status: 501\r\n\r\n") == -1)
404 			return;
405 		fcgi_end_request(clt, 1);
406 		return;
407 	}
408 
409 	(void)snprintf(port, sizeof(port), "%d", clt->clt_pc->proxy_port);
410 
411 	memset(&hints, 0, sizeof(hints));
412 	hints.ai_family = AF_UNSPEC;
413 	hints.ai_socktype = SOCK_STREAM;
414 
415 	query = getaddrinfo_async(clt->clt_pc->proxy_addr, port, &hints, NULL);
416 	if (query == NULL) {
417 		log_warn("getaddrinfo_async");
418 		fcgi_abort_request(clt);
419 		return;
420 	}
421 
422 	clt->clt_evasr = event_asr_run(query, proxy_resolved, clt);
423 	if (clt->clt_evasr == NULL) {
424 		log_warn("event_asr_run");
425 		asr_abort(query);
426 		fcgi_abort_request(clt);
427 		return;
428 	}
429 }
430 
431 void
432 proxy_resolved(struct asr_result *res, void *d)
433 {
434 	struct client		*clt = d;
435 	struct proxy_config	*pc = clt->clt_pc;
436 
437 	clt->clt_evasr = NULL;
438 
439 	if (res->ar_gai_errno != 0) {
440 		log_warnx("failed to resolve %s:%d: %s",
441 		    pc->proxy_addr, pc->proxy_port,
442 		    gai_strerror(res->ar_gai_errno));
443 		if (clt_printf(clt, "Status: 501\r\n") == -1)
444 			return;
445 		if (clt_printf(clt, "Content-Type: text/plain\r\n") == -1)
446 			return;
447 		if (clt_printf(clt, "Proxy error; connection failed") == -1)
448 			return;
449 		fcgi_end_request(clt, 1);
450 		return;
451 	}
452 
453 	clt->clt_addrinfo = res->ar_addrinfo;
454 	clt->clt_p = clt->clt_addrinfo;
455 	proxy_connect(-1, 0, clt);
456 }
457 
458 void
459 proxy_connect(int fd, short ev, void *d)
460 {
461 	struct client		*clt = d;
462 	struct evbuffer		*out;
463 	struct addrinfo		*p;
464 	struct tls_config	*conf;
465 	struct timeval		 conntv = {5, 0};
466 	int			 err = 0;
467 	socklen_t		 len = sizeof(err);
468 
469 again:
470 	if (clt->clt_p == NULL)
471 		goto err;
472 
473 	if (clt->clt_fd != -1) {
474 		if (getsockopt(clt->clt_fd, SOL_SOCKET, SO_ERROR, &err, &len)
475 		    == -1)
476 			goto err;
477 		if (err != 0) {
478 			errno = err;
479 			goto err;
480 		}
481 		goto done;
482 	}
483 
484 	p = clt->clt_p;
485 	clt->clt_fd = socket(p->ai_family, p->ai_socktype | SOCK_NONBLOCK,
486 	    p->ai_protocol);
487 	if (clt->clt_fd == -1) {
488 		clt->clt_p = clt->clt_p->ai_next;
489 		goto again;
490 	}
491 
492 	if (connect(clt->clt_fd, p->ai_addr, p->ai_addrlen) == 0)
493 		goto done;
494 
495 	clt->clt_evconn_live = 1;
496 	event_set(&clt->clt_evconn, clt->clt_fd, EV_WRITE, proxy_connect, clt);
497 	event_add(&clt->clt_evconn, &conntv);
498 	return;
499 
500 done:
501 	clt->clt_evconn_live = 0;
502 	freeaddrinfo(clt->clt_addrinfo);
503 	clt->clt_addrinfo = clt->clt_p = NULL;
504 
505 	/* initialize TLS for Gemini */
506 	if ((conf = tls_config_new()) == NULL) {
507 		log_warn("tls_config_new failed");
508 		goto err;
509 	}
510 
511 	tls_config_insecure_noverifycert(conf);
512 
513 	if ((clt->clt_ctx = tls_client()) == NULL) {
514 		log_warnx("tls_client failed");
515 		tls_config_free(conf);
516 		goto err;
517 	}
518 
519 	if (tls_configure(clt->clt_ctx, conf) == -1) {
520 		log_warnx("tls_configure failed");
521 		tls_config_free(conf);
522 		goto err;
523 	}
524 
525 	tls_config_free(conf);
526 
527 	if (tls_connect_socket(clt->clt_ctx, clt->clt_fd,
528 	    clt->clt_pc->proxy_name) == -1) {
529 		log_warnx("tls_connect_socket failed");
530 		goto err;
531 	}
532 
533 	clt->clt_bev = bufferevent_new(clt->clt_fd, proxy_read, proxy_write,
534 	    proxy_error, clt);
535 	if (clt->clt_bev == NULL) {
536 		log_warn("bufferevent_new");
537 		goto err;
538 	}
539 	out = EVBUFFER_OUTPUT(clt->clt_bev);
540 
541 	event_set(&clt->clt_bev->ev_read, clt->clt_fd, EV_READ,
542 	    proxy_tls_readcb, clt->clt_bev);
543 	event_set(&clt->clt_bev->ev_write, clt->clt_fd, EV_WRITE,
544 	    proxy_tls_writecb, clt->clt_bev);
545 
546 	/* bufferevent_settimeout(); */
547 	bufferevent_enable(clt->clt_bev, EV_READ|EV_WRITE);
548 
549 	/* TODO: compute the URL */
550 	if (evbuffer_add_printf(out, "gemini://%s/%s\r\n",
551 	    clt->clt_pc->proxy_name, clt->clt_path_info) == -1) {
552 		log_warn("bufferevent_printf failed");
553 		goto err;
554 	}
555 
556 	return;
557 
558 err:
559 	log_warn("failed to connect to %s:%d",
560 	    clt->clt_pc->proxy_addr, clt->clt_pc->proxy_port);
561 	if (clt_printf(clt, "Status: 501\r\n") == -1)
562 		return;
563 	if (clt_printf(clt, "Content-Type: text/plain\r\n") == -1)
564 		return;
565 	if (clt_printf(clt, "Proxy error; connection failed") == -1)
566 		return;
567 	fcgi_end_request(clt, 1);
568 }
569 
570 static inline int
571 parse_mime(struct client *clt, char *mime, char *lang, size_t len)
572 {
573 	char			*t, *semi;
574 
575 	if (strncmp(mime, "text/gemini", 11) != 0)
576 		return (0);
577 
578 	clt->clt_translate = TR_ENABLED;
579 
580 	if ((mime = strchr(mime, ';')) == NULL)
581 		return (0);
582 
583 	*mime++ = '\0';
584 	while ((t = strsep(&mime, ";")) != NULL) {
585 		if (!strncmp(t, "charset=", 8)) {
586 			t += 8;
587 			if (!strncasecmp(t, "utf8", 4) ||
588 			    !strncasecmp(t, "ascii", 5)) {
589 				log_debug("unknown charset %s", t);
590 				return (-1);
591 			}
592 			continue;
593 		}
594 
595 		if (!strncmp(t, "lang=", 5)) {
596 			t += 5;
597 			if ((semi = strchr(t, ';')) != NULL)
598 				*semi = '\0';
599 
600 			if (strlcpy(lang, t, len) >= len) {
601 				log_debug("lang too long: %s", t);
602 				*lang = '\0';
603 			}
604 
605 			if (semi)
606 				*semi = ';';
607 			continue;
608 		}
609 	}
610 
611 	return (0);
612 }
613 
614 void
615 proxy_read(struct bufferevent *bev, void *d)
616 {
617 	struct client		*clt = d;
618 	struct proxy_config	*pc = clt->clt_pc;
619 	struct evbuffer		*src = EVBUFFER_INPUT(bev);
620 	const char		*ctype;
621 	char			 lang[16];
622 	char			*hdr, *mime;
623 	size_t			 len;
624 
625 	if (clt->clt_headersdone) {
626 		if (clt->clt_translate)
627 			proxy_translate_gemtext(clt);
628 		else
629 			clt_write_bufferevent(clt, bev);
630 		return;
631 	}
632 
633 	hdr = evbuffer_readln(src, &len, EVBUFFER_EOL_CRLF_STRICT);
634 	if (hdr == NULL) {
635 		if (EVBUFFER_LENGTH(src) >= 1026)
636 			proxy_error(bev, EV_READ, clt);
637 		return;
638 	}
639 
640 	if (len < 4 ||
641 	    !isdigit((unsigned char)hdr[0]) ||
642 	    !isdigit((unsigned char)hdr[1]) ||
643 	    hdr[2] != ' ') {
644 		log_warnx("invalid ");
645 		proxy_error(bev, EV_READ, clt);
646 		goto err;
647 	}
648 
649 	switch (hdr[0]) {
650 	case '2':
651 		/* handled below */
652 		break;
653 	default:
654 		if (clt_puts(clt, "Status: 501\r\n") == -1)
655 			goto err;
656 		if (clt_puts(clt,
657 		    "Content-Type: text/plain;charset=utf8\r\n") == -1)
658 			goto err;
659 		if (clt_puts(clt, "\r\n") == -1)
660 			goto err;
661 		if (clt_printf(clt, "Request failed with code %c%c\n\n",
662 		    hdr[0], hdr[1]) == -1)
663 			goto err;
664 		if (clt_printf(clt, "The server says: %s\n", &hdr[3]) == -1)
665 			goto err;
666 		fcgi_end_request(clt, 1);
667 		goto err;
668 	}
669 
670 	mime = hdr + 2 + strspn(hdr + 2, " \t");
671 	if (parse_mime(clt, mime, lang, sizeof(lang)) == -1) {
672 		if (clt_puts(clt, "Status: 501\r\n") == -1)
673 			goto err;
674 		if (clt_puts(clt,
675 		    "Content-Type: text/plain;charset=utf8\r\n") == -1)
676 			goto err;
677 		if (clt_puts(clt, "\r\n") == -1)
678 			goto err;
679 		if (clt_printf(clt, "Failed to parse the Gemini response\n")
680 		    == -1)
681 		fcgi_end_request(clt, 1);
682 		goto err;
683 	}
684 
685 	if (clt->clt_translate)
686 		ctype = "text/html;charset=utf8";
687 	else
688 		ctype = mime;
689 
690 	if (clt_printf(clt, "Content-Type: %s\r\n\r\n", ctype) == -1)
691 		goto err;
692 
693 	clt->clt_headersdone = 1;
694 
695 	if (clt->clt_translate) {
696 		if (clt_puts(clt, "<!doctype html><html") == -1)
697 			goto err;
698 		if (*lang != '\0') {
699 			if (clt_puts(clt, " lang='") == -1 ||
700 			    printurl(clt, lang) == -1 ||
701 			    clt_puts(clt, "'") == -1)
702 				goto err;
703 		}
704 		if (clt_puts(clt, "><head>") == -1)
705 			goto err;
706 		if (*pc->stylesheet != '\0' &&
707 		    clt_printf(clt, "<link rel='stylesheet' href='%s' />",
708 		    pc->stylesheet) == -1)
709 			goto err;
710 		if (clt_puts(clt, "</head><body>") == -1)
711 			goto err;
712 	}
713 
714 	/*
715 	 * Trigger the read again so we proceed with the response
716 	 * body, if any.
717 	 */
718 	free(hdr);
719 	proxy_read(bev, d);
720 	return;
721 
722 err:
723 	free(hdr);
724 }
725 
726 void
727 proxy_write(struct bufferevent *bev, void *d)
728 {
729 	return;
730 }
731 
732 void
733 proxy_error(struct bufferevent *bev, short err, void *d)
734 {
735 	struct client		*clt = d;
736 	int			 status = !(err & EVBUFFER_EOF);
737 
738 	log_debug("proxy error, shutting down the connection (err: %x)",
739 	    err);
740 
741 	if (!clt->clt_headersdone) {
742 		if (clt_printf(clt, "Status: 501\r\n") == -1)
743 			return;
744 		if (clt_printf(clt, "Content-Type: text/plain\r\n") == -1)
745 			return;
746 		if (clt_printf(clt, "Proxy error\n") == -1)
747 			return;
748 	} else if (status == 0) {
749 		if (clt_puts(clt, "<footer>") == -1 ||
750 		    clt_puts(clt, "<hr />") == -1 ||
751 		    clt_puts(clt, "<dl>") == -1 ||
752 		    clt_puts(clt, "<dt>Original URL:</dt>") == -1 ||
753 		    clt_puts(clt, "<dd><a href='gemini://") == -1 ||
754 		    printurl(clt, clt->clt_pc->proxy_name) == -1 ||
755 		    printurl(clt, clt->clt_path_info) == -1 ||
756 		    clt_puts(clt, "'>gemini://") == -1 ||
757 		    htmlescape(clt, clt->clt_pc->proxy_name) == -1 ||
758 		    htmlescape(clt, clt->clt_path_info) == -1 ||
759 		    clt_puts(clt, "</a></dd>") == -1 ||
760 		    clt_puts(clt, "</footer>") == -1)
761 			return;
762 		if (clt_puts(clt, "</body></html>") == -1)
763 			return;
764 	}
765 
766 	fcgi_end_request(clt, status);
767 }
768 
769 void
770 proxy_tls_readcb(int fd, short event, void *arg)
771 {
772 	struct bufferevent	*bufev = arg;
773 	struct client		*clt = bufev->cbarg;
774 	char			 rbuf[IBUF_READ_SIZE];
775 	int			 what = EVBUFFER_READ;
776 	int			 howmuch = IBUF_READ_SIZE;
777 	ssize_t			 ret;
778 	size_t			 len;
779 
780 	if (event == EV_TIMEOUT) {
781 		what |= EVBUFFER_TIMEOUT;
782 		goto err;
783 	}
784 
785 	if (bufev->wm_read.high != 0)
786 		howmuch = MINIMUM(sizeof(rbuf), bufev->wm_read.high);
787 
788 	ret = tls_read(clt->clt_ctx, rbuf, howmuch);
789 	if (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT) {
790 		goto retry;
791 	} else if (ret == -1) {
792 		what |= EVBUFFER_ERROR;
793 		goto err;
794 	}
795 	len = ret;
796 
797 	if (len == 0) {
798 		what |= EVBUFFER_EOF;
799 		goto err;
800 	}
801 
802 	if (evbuffer_add(bufev->input, rbuf, len) == -1) {
803 		what |= EVBUFFER_ERROR;
804 		goto err;
805 	}
806 
807 	proxy_bufferevent_add(&bufev->ev_read, bufev->timeout_read);
808 
809 	len = EVBUFFER_LENGTH(bufev->input);
810 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
811 		return;
812 	if (bufev->wm_read.high != 0 && len > bufev->wm_read.high) {
813 		struct evbuffer *buf = bufev->input;
814 		event_del(&bufev->ev_read);
815 		evbuffer_setcb(buf, bufferevent_read_pressure_cb, bufev);
816 		return;
817 	}
818 
819 	if (bufev->readcb != NULL)
820 		(*bufev->readcb)(bufev, bufev->cbarg);
821 	return;
822 
823 retry:
824 	proxy_bufferevent_add(&bufev->ev_read, bufev->timeout_read);
825 	return;
826 
827 err:
828 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
829 }
830 
831 int
832 proxy_bufferevent_add(struct event *ev, int timeout)
833 {
834 	struct timeval tv, *ptv = NULL;
835 
836 	if (timeout) {
837 		timerclear(&tv);
838 		tv.tv_sec = timeout;
839 		ptv = &tv;
840 	}
841 
842 	return (event_add(ev, ptv));
843 }
844 
845 void
846 proxy_tls_writecb(int fd, short event, void *arg)
847 {
848 	struct bufferevent	*bufev = arg;
849 	struct client		*clt = bufev->cbarg;
850 	ssize_t			 ret;
851 	short			 what = EVBUFFER_WRITE;
852 	size_t			 len;
853 
854 	if (event == EV_TIMEOUT) {
855 		what |= EVBUFFER_TIMEOUT;
856 		goto err;
857 	}
858 
859 	if (EVBUFFER_LENGTH(bufev->output)) {
860 		ret = tls_write(clt->clt_ctx,
861 		    EVBUFFER_DATA(bufev->output),
862 		    EVBUFFER_LENGTH(bufev->output));
863 		if (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT) {
864 			goto retry;
865 		} else if (ret == -1) {
866 			what |= EVBUFFER_ERROR;
867 			goto err;
868 		}
869 		len = ret;
870 		evbuffer_drain(bufev->output, len);
871 	}
872 
873 	if (EVBUFFER_LENGTH(bufev->output) != 0)
874 		proxy_bufferevent_add(&bufev->ev_write, bufev->timeout_write);
875 
876 	if (bufev->writecb != NULL &&
877 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
878 		(*bufev->writecb)(bufev, bufev->cbarg);
879 	return;
880 
881 retry:
882 	proxy_bufferevent_add(&bufev->ev_write, bufev->timeout_write);
883 	return;
884 
885 err:
886 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
887 }
888 
889 void
890 proxy_client_free(struct client *clt)
891 {
892 	if (clt->clt_evasr)
893 		event_asr_abort(clt->clt_evasr);
894 
895 	if (clt->clt_addrinfo)
896 		freeaddrinfo(clt->clt_addrinfo);
897 
898 	if (clt->clt_evconn_live)
899 		event_del(&clt->clt_evconn);
900 
901 	if (clt->clt_fd != -1)
902 		close(clt->clt_fd);
903 
904 	if (clt->clt_ctx)
905 		tls_free(clt->clt_ctx);
906 
907 	if (clt->clt_bev)
908 		bufferevent_free(clt->clt_bev);
909 
910 	free(clt->clt_server_name);
911 	free(clt->clt_script_name);
912 	free(clt->clt_path_info);
913 	free(clt);
914 }