1 /*
2  * Copyright (c) 2020-2022 Tracey Emery <tracey@traceyemery.net>
3  * Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
4  * Copyright (c) 2013 Florian Obser <florian@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <arpa/inet.h>
20 #include <sys/queue.h>
21 #include <sys/socket.h>
22 #include <sys/types.h>
23 #include <sys/uio.h>
24 
25 #include <errno.h>
26 #include <event.h>
27 #include <imsg.h>
28 #include <stdarg.h>
29 #include <stdlib.h>
30 #include <stdio.h>
31 #include <string.h>
32 #include <time.h>
33 #include <unistd.h>
34 
35 #include "got_error.h"
36 
37 #include "got_compat.h"
38 
39 #include "proc.h"
40 #include "gotwebd.h"
41 
42 size_t	 fcgi_parse_record(uint8_t *, size_t, struct request *);
43 void	 fcgi_parse_begin_request(uint8_t *, uint16_t, struct request *,
44 	    uint16_t);
45 void	 fcgi_parse_params(uint8_t *, uint16_t, struct request *, uint16_t);
46 int	 fcgi_send_response(struct request *, int, const void *, size_t);
47 
48 void	 dump_fcgi_record_header(const char *, struct fcgi_record_header *);
49 void	 dump_fcgi_begin_request_body(const char *,
50 	    struct fcgi_begin_request_body *);
51 void	 dump_fcgi_end_request_body(const char *,
52 	    struct fcgi_end_request_body *);
53 
54 extern int	 cgi_inflight;
55 extern volatile int client_cnt;
56 
57 void
58 fcgi_request(int fd, short events, void *arg)
59 {
60 	struct request *c = arg;
61 	ssize_t n;
62 	size_t parsed = 0;
63 
64 	n = read(fd, c->buf + c->buf_pos + c->buf_len,
65 	    FCGI_RECORD_SIZE - c->buf_pos-c->buf_len);
66 
67 	switch (n) {
68 	case -1:
69 		switch (errno) {
70 		case EINTR:
71 		case EAGAIN:
72 			return;
73 		default:
74 			goto fail;
75 		}
76 		break;
77 
78 	case 0:
79 		log_debug("closed connection");
80 		goto fail;
81 	default:
82 		break;
83 	}
84 
85 	c->buf_len += n;
86 
87 	/*
88 	 * Parse the records as they are received. Per the FastCGI
89 	 * specification, the server need only receive the FastCGI
90 	 * parameter records in full; it is free to begin execution
91 	 * at that point, which is what happens here.
92 	 */
93 	do {
94 		parsed = fcgi_parse_record(c->buf + c->buf_pos, c->buf_len, c);
95 		if (parsed != 0) {
96 			c->buf_pos += parsed;
97 			c->buf_len -= parsed;
98 		}
99 	} while (parsed > 0 && c->buf_len > 0);
100 
101 	/* Make space for further reads */
102 	if (parsed != 0)
103 		if (c->buf_len > 0) {
104 			bcopy(c->buf + c->buf_pos, c->buf, c->buf_len);
105 			c->buf_pos = 0;
106 		}
107 	return;
108 fail:
109 	fcgi_cleanup_request(c);
110 }
111 
112 size_t
113 fcgi_parse_record(uint8_t *buf, size_t n, struct request *c)
114 {
115 	struct fcgi_record_header *h;
116 
117 	if (n < sizeof(struct fcgi_record_header))
118 		 return 0;
119 
120 	h = (struct fcgi_record_header*) buf;
121 
122 	dump_fcgi_record("", h);
123 
124 	if (n < sizeof(struct fcgi_record_header) + ntohs(h->content_len)
125 	    + h->padding_len)
126 		 return 0;
127 
128 	if (h->version != 1)
129 		log_warn("wrong version");
130 
131 	switch (h->type) {
132 	case FCGI_BEGIN_REQUEST:
133 		fcgi_parse_begin_request(buf +
134 		    sizeof(struct fcgi_record_header),
135 		    ntohs(h->content_len), c, ntohs(h->id));
136 		break;
137 	case FCGI_PARAMS:
138 		fcgi_parse_params(buf + sizeof(struct fcgi_record_header),
139 		    ntohs(h->content_len), c, ntohs(h->id));
140 		break;
141 	case FCGI_STDIN:
142 	case FCGI_ABORT_REQUEST:
143 		if (c->sock->client_status != CLIENT_DISCONNECT &&
144 		    c->outbuf_len != 0) {
145 			fcgi_send_response(c, FCGI_STDOUT, c->outbuf,
146 			    c->outbuf_len);
147 		}
148 
149 		fcgi_create_end_record(c);
150 		fcgi_cleanup_request(c);
151 		return 0;
152 	default:
153 		log_warn("unimplemented type %d", h->type);
154 		break;
155 	}
156 
157 	return (sizeof(struct fcgi_record_header) + ntohs(h->content_len)
158 	    + h->padding_len);
159 }
160 
161 void
162 fcgi_parse_begin_request(uint8_t *buf, uint16_t n,
163     struct request *c, uint16_t id)
164 {
165 	/* XXX -- FCGI_CANT_MPX_CONN */
166 	if (c->request_started) {
167 		log_warn("unexpected FCGI_BEGIN_REQUEST, ignoring");
168 		return;
169 	}
170 
171 	if (n != sizeof(struct fcgi_begin_request_body)) {
172 		log_warn("wrong size %d != %lu", n,
173 		    sizeof(struct fcgi_begin_request_body));
174 		return;
175 	}
176 
177 	c->request_started = 1;
178 
179 	c->id = id;
180 	SLIST_INIT(&c->env);
181 	c->env_count = 0;
182 }
183 
184 void
185 fcgi_parse_params(uint8_t *buf, uint16_t n, struct request *c, uint16_t id)
186 {
187 	struct env_val *env_entry;
188 	uint32_t name_len, val_len;
189 	uint8_t *sd, *dr_buf;
190 
191 	if (!c->request_started) {
192 		log_warn("FCGI_PARAMS without FCGI_BEGIN_REQUEST, ignoring");
193 		return;
194 	}
195 
196 	if (c->id != id) {
197 		log_warn("unexpected id, ignoring");
198 		return;
199 	}
200 
201 	if (n == 0) {
202 		gotweb_process_request(c);
203 		return;
204 	}
205 
206 	while (n > 0) {
207 		if (buf[0] >> 7 == 0) {
208 			name_len = buf[0];
209 			n--;
210 			buf++;
211 		} else {
212 			if (n > 3) {
213 				name_len = ((buf[0] & 0x7f) << 24) +
214 				    (buf[1] << 16) + (buf[2] << 8) + buf[3];
215 				n -= 4;
216 				buf += 4;
217 			} else
218 				return;
219 		}
220 
221 		if (n > 0) {
222 			if (buf[0] >> 7 == 0) {
223 				val_len = buf[0];
224 				n--;
225 				buf++;
226 			} else {
227 				if (n > 3) {
228 					val_len = ((buf[0] & 0x7f) << 24) +
229 					    (buf[1] << 16) + (buf[2] << 8) +
230 					     buf[3];
231 					n -= 4;
232 					buf += 4;
233 				} else
234 					return;
235 			}
236 		} else
237 			return;
238 
239 		if (n < name_len + val_len)
240 			return;
241 
242 		if ((env_entry = malloc(sizeof(struct env_val))) == NULL) {
243 			log_warn("cannot malloc env_entry");
244 			return;
245 		}
246 
247 		if ((env_entry->val = calloc(sizeof(char), name_len + val_len +
248 		    2)) == NULL) {
249 			log_warn("cannot allocate env_entry->val");
250 			free(env_entry);
251 			return;
252 		}
253 
254 		bcopy(buf, env_entry->val, name_len);
255 		buf += name_len;
256 		n -= name_len;
257 
258 		env_entry->val[name_len] = '\0';
259 		if (val_len < MAX_QUERYSTRING && strcmp(env_entry->val,
260 		    "QUERY_STRING") == 0 && c->querystring[0] == '\0') {
261 			bcopy(buf, c->querystring, val_len);
262 			c->querystring[val_len] = '\0';
263 		}
264 		if (val_len < GOTWEBD_MAXTEXT && strcmp(env_entry->val,
265 		    "HTTP_HOST") == 0 && c->http_host[0] == '\0') {
266 
267 			/*
268 			 * lazily get subdomain
269 			 * will only get domain if no subdomain exists
270 			 * this can still work if gotweb server name is the same
271 			 */
272 			sd = strchr(buf, '.');
273 			if (sd)
274 				*sd = '\0';
275 
276 			bcopy(buf, c->http_host, val_len);
277 			c->http_host[val_len] = '\0';
278 		}
279 		if (val_len < MAX_SCRIPT_NAME && strcmp(env_entry->val,
280 		    "SCRIPT_NAME") == 0 && c->script_name[0] == '\0') {
281 			bcopy(dr_buf, c->script_name, val_len);
282 			c->script_name[val_len] = '\0';
283 		}
284 		if (val_len < MAX_SERVER_NAME && strcmp(env_entry->val,
285 		    "SERVER_NAME") == 0 && c->server_name[0] == '\0') {
286 			bcopy(buf, c->server_name, val_len);
287 			c->server_name[val_len] = '\0';
288 		}
289 		env_entry->val[name_len] = '=';
290 
291 		bcopy(buf, (env_entry->val) + name_len + 1, val_len);
292 		buf += val_len;
293 		n -= val_len;
294 
295 		SLIST_INSERT_HEAD(&c->env, env_entry, entry);
296 		log_debug("env[%d], %s", c->env_count, env_entry->val);
297 		c->env_count++;
298 	}
299 }
300 
301 void
302 fcgi_timeout(int fd, short events, void *arg)
303 {
304 	fcgi_cleanup_request((struct request*) arg);
305 }
306 
307 int
308 fcgi_printf(struct request *c, const char *fmt, ...)
309 {
310 	va_list ap;
311 	char *str;
312 	int r;
313 
314 	va_start(ap, fmt);
315 	r = vasprintf(&str, fmt, ap);
316 	va_end(ap);
317 
318 	if (r == -1) {
319 		log_warn("%s: asprintf", __func__);
320 		return -1;
321 	}
322 
323 	r = fcgi_gen_binary_response(c, str, r);
324 	free(str);
325 	return r;
326 }
327 
328 int
329 fcgi_gen_binary_response(struct request *c, const uint8_t *data, int len)
330 {
331 	int r;
332 
333 	if (c->sock->client_status == CLIENT_DISCONNECT)
334 		return -1;
335 
336 	if (data == NULL || len == 0)
337 		return 0;
338 
339 	/*
340 	 * special case: send big replies -like blobs- directly
341 	 * without copying.
342 	 */
343 	if (len > sizeof(c->outbuf)) {
344 		if (c->outbuf_len > 0) {
345 			fcgi_send_response(c, FCGI_STDOUT,
346 			    c->outbuf, c->outbuf_len);
347 			c->outbuf_len = 0;
348 		}
349 		return fcgi_send_response(c, FCGI_STDOUT, data, len);
350 	}
351 
352 	if (len < sizeof(c->outbuf) - c->outbuf_len) {
353 		memcpy(c->outbuf + c->outbuf_len, data, len);
354 		c->outbuf_len += len;
355 		return 0;
356 	}
357 
358 	r = fcgi_send_response(c, FCGI_STDOUT, c->outbuf, c->outbuf_len);
359 	if (r == -1)
360 		return -1;
361 
362 	memcpy(c->outbuf, data, len);
363 	c->outbuf_len = len;
364 	return 0;
365 }
366 
367 static int
368 send_response(struct request *c, int type, const uint8_t *data,
369     size_t len)
370 {
371 	static const uint8_t padding[FCGI_PADDING_SIZE];
372 	struct fcgi_record_header header;
373 	struct iovec iov[3];
374 	struct timespec ts;
375 	ssize_t nw;
376 	size_t padded_len, tot;
377 	int i, err = 0, th = 2000;
378 
379 	ts.tv_sec = 0;
380 	ts.tv_nsec = 50;
381 
382 	memset(&header, 0, sizeof(header));
383 	header.version = 1;
384 	header.type = type;
385 	header.id = htons(c->id);
386 	header.content_len = htons(len);
387 
388 	/* The FastCGI spec suggests to align the output buffer */
389 	tot = sizeof(header) + len;
390 	padded_len = FCGI_ALIGN(tot);
391 	if (padded_len > tot) {
392 		header.padding_len = padded_len - tot;
393 		tot += header.padding_len;
394 	}
395 
396 	iov[0].iov_base = &header;
397 	iov[0].iov_len = sizeof(header);
398 
399 	iov[1].iov_base = (void *)data;
400 	iov[1].iov_len = len;
401 
402 	iov[2].iov_base = (void *)padding;
403 	iov[2].iov_len = header.padding_len;
404 
405 	dump_fcgi_record("resp ", &header);
406 
407 	/*
408 	 * XXX: add some simple write heuristics here
409 	 * On slower VMs, spotty connections, etc., we don't want to go right to
410 	 * disconnect. Let's at least try to write the data a few times before
411 	 * giving up.
412 	 */
413 	while (tot > 0) {
414 		nw = writev(c->fd, iov, nitems(iov));
415 		if (nw == 0) {
416 			c->sock->client_status = CLIENT_DISCONNECT;
417 			break;
418 		}
419 		if (nw == -1) {
420 			err++;
421 			if (errno == EAGAIN && err < th) {
422 				nanosleep(&ts, NULL);
423 				continue;
424 			}
425 			log_warn("%s: write failure", __func__);
426 			c->sock->client_status = CLIENT_DISCONNECT;
427 			return -1;
428 		}
429 
430 		if (nw != tot)
431 			log_debug("%s: partial write: %zu vs %zu", __func__,
432 			    nw, tot);
433 
434 		tot -= nw;
435 		for (i = 0; i < nitems(iov); ++i) {
436 			if (nw < iov[i].iov_len) {
437 				iov[i].iov_base += nw;
438 				iov[i].iov_len -= nw;
439 				break;
440 			}
441 			nw -= iov[i].iov_len;
442 			iov[i].iov_len = 0;
443 		}
444 	}
445 
446 	return 0;
447 }
448 
449 int
450 fcgi_send_response(struct request *c, int type, const void *data,
451     size_t len)
452 {
453 	if (c->sock->client_status == CLIENT_DISCONNECT)
454 		return -1;
455 
456 	while (len > FCGI_CONTENT_SIZE) {
457 		if (send_response(c, type, data, len) == -1)
458 			return -1;
459 
460 		data += FCGI_CONTENT_SIZE;
461 		len -= FCGI_CONTENT_SIZE;
462 	}
463 
464 	if (len == 0)
465 		return 0;
466 
467 	return send_response(c, type, data, len);
468 }
469 
470 void
471 fcgi_create_end_record(struct request *c)
472 {
473 	struct fcgi_end_request_body end_request;
474 
475 	memset(&end_request, 0, sizeof(end_request));
476 	end_request.app_status = htonl(0); /* script status */
477 	end_request.protocol_status = FCGI_REQUEST_COMPLETE;
478 
479 	fcgi_send_response(c, FCGI_END_REQUEST, &end_request,
480 	    sizeof(end_request));
481 }
482 
483 void
484 fcgi_cleanup_request(struct request *c)
485 {
486 	cgi_inflight--;
487 	client_cnt--;
488 
489 	evtimer_del(&c->tmo);
490 	if (event_initialized(&c->ev))
491 		event_del(&c->ev);
492 
493 	close(c->fd);
494 	gotweb_free_transport(c->t);
495 	free(c);
496 }
497 
498 void
499 dump_fcgi_record(const char *p, struct fcgi_record_header *h)
500 {
501 	dump_fcgi_record_header(p, h);
502 
503 	if (h->type == FCGI_BEGIN_REQUEST)
504 		dump_fcgi_begin_request_body(p,
505 		    (struct fcgi_begin_request_body *)(h + 1));
506 	else if (h->type == FCGI_END_REQUEST)
507 		dump_fcgi_end_request_body(p,
508 		    (struct fcgi_end_request_body *)(h + 1));
509 }
510 
511 void
512 dump_fcgi_record_header(const char* p, struct fcgi_record_header *h)
513 {
514 	log_debug("%sversion:         %d", p, h->version);
515 	log_debug("%stype:            %d", p, h->type);
516 	log_debug("%srequestId:       %d", p, ntohs(h->id));
517 	log_debug("%scontentLength:   %d", p, ntohs(h->content_len));
518 	log_debug("%spaddingLength:   %d", p, h->padding_len);
519 	log_debug("%sreserved:        %d", p, h->reserved);
520 }
521 
522 void
523 dump_fcgi_begin_request_body(const char *p, struct fcgi_begin_request_body *b)
524 {
525 	log_debug("%srole             %d", p, ntohs(b->role));
526 	log_debug("%sflags            %d", p, b->flags);
527 }
528 
529 void
530 dump_fcgi_end_request_body(const char *p, struct fcgi_end_request_body *b)
531 {
532 	log_debug("%sappStatus:       %d", p, ntohl(b->app_status));
533 	log_debug("%sprotocolStatus:  %d", p, b->protocol_status);
534 }