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 "got_compat.h"
20 
21 #include <arpa/inet.h>
22 #include <sys/queue.h>
23 #include <sys/socket.h>
24 #include <sys/types.h>
25 #include <sys/uio.h>
26 
27 #include <errno.h>
28 #include <event.h>
29 #include <imsg.h>
30 #include <stdarg.h>
31 #include <stdlib.h>
32 #include <stdio.h>
33 #include <string.h>
34 #include <time.h>
35 #include <unistd.h>
36 
37 #include "got_error.h"
38 #include "got_reference.h"
39 
40 #include "gotwebd.h"
41 #include "tmpl.h"
42 
43 size_t	 fcgi_parse_record(uint8_t *, size_t, struct request *);
44 void	 fcgi_parse_begin_request(uint8_t *, uint16_t, struct request *,
45 	    uint16_t);
46 void	 fcgi_parse_params(uint8_t *, uint16_t, struct request *, uint16_t);
47 int	 fcgi_send_response(struct request *, int, const void *, size_t);
48 
49 void	 dump_fcgi_record_header(const char *, struct fcgi_record_header *);
50 void	 dump_fcgi_begin_request_body(const char *,
51 	    struct fcgi_begin_request_body *);
52 void	 dump_fcgi_end_request_body(const char *,
53 	    struct fcgi_end_request_body *);
54 
55 extern int	 cgi_inflight;
56 extern volatile int client_cnt;
57 
58 void
59 fcgi_request(int fd, short events, void *arg)
60 {
61 	struct request *c = arg;
62 	ssize_t n;
63 	size_t parsed = 0;
64 
65 	n = read(fd, c->buf + c->buf_pos + c->buf_len,
66 	    FCGI_RECORD_SIZE - c->buf_pos-c->buf_len);
67 
68 	switch (n) {
69 	case -1:
70 		switch (errno) {
71 		case EINTR:
72 		case EAGAIN:
73 			return;
74 		default:
75 			goto fail;
76 		}
77 		break;
78 
79 	case 0:
80 		log_debug("closed connection");
81 		goto fail;
82 	default:
83 		break;
84 	}
85 
86 	c->buf_len += n;
87 
88 	/*
89 	 * Parse the records as they are received. Per the FastCGI
90 	 * specification, the server need only receive the FastCGI
91 	 * parameter records in full; it is free to begin execution
92 	 * at that point, which is what happens here.
93 	 */
94 	do {
95 		parsed = fcgi_parse_record(c->buf + c->buf_pos, c->buf_len, c);
96 		if (parsed != 0) {
97 			c->buf_pos += parsed;
98 			c->buf_len -= parsed;
99 		}
100 
101 		/* drop the parsed record */
102 		if (parsed != 0 && c->buf_len > 0) {
103 			bcopy(c->buf + c->buf_pos, c->buf, c->buf_len);
104 			c->buf_pos = 0;
105 		}
106 	} while (parsed > 0 && c->buf_len > 0);
107 
108 	return;
109 fail:
110 	fcgi_cleanup_request(c);
111 }
112 
113 size_t
114 fcgi_parse_record(uint8_t *buf, size_t n, struct request *c)
115 {
116 	struct fcgi_record_header *h;
117 
118 	if (n < sizeof(struct fcgi_record_header))
119 		 return 0;
120 
121 	h = (struct fcgi_record_header*) buf;
122 
123 	dump_fcgi_record("", h);
124 
125 	if (n < sizeof(struct fcgi_record_header) + ntohs(h->content_len)
126 	    + h->padding_len)
127 		 return 0;
128 
129 	if (h->version != 1)
130 		log_warn("wrong version");
131 
132 	switch (h->type) {
133 	case FCGI_BEGIN_REQUEST:
134 		fcgi_parse_begin_request(buf +
135 		    sizeof(struct fcgi_record_header),
136 		    ntohs(h->content_len), c, ntohs(h->id));
137 		break;
138 	case FCGI_PARAMS:
139 		fcgi_parse_params(buf + sizeof(struct fcgi_record_header),
140 		    ntohs(h->content_len), c, ntohs(h->id));
141 		break;
142 	case FCGI_STDIN:
143 	case FCGI_ABORT_REQUEST:
144 		fcgi_create_end_record(c);
145 		fcgi_cleanup_request(c);
146 		return 0;
147 	default:
148 		log_warn("unimplemented type %d", h->type);
149 		break;
150 	}
151 
152 	return (sizeof(struct fcgi_record_header) + ntohs(h->content_len)
153 	    + h->padding_len);
154 }
155 
156 void
157 fcgi_parse_begin_request(uint8_t *buf, uint16_t n,
158     struct request *c, uint16_t id)
159 {
160 	/* XXX -- FCGI_CANT_MPX_CONN */
161 	if (c->request_started) {
162 		log_warn("unexpected FCGI_BEGIN_REQUEST, ignoring");
163 		return;
164 	}
165 
166 	if (n != sizeof(struct fcgi_begin_request_body)) {
167 		log_warn("wrong size %d != %lu", n,
168 		    sizeof(struct fcgi_begin_request_body));
169 		return;
170 	}
171 
172 	c->request_started = 1;
173 	c->id = id;
174 }
175 
176 void
177 fcgi_parse_params(uint8_t *buf, uint16_t n, struct request *c, uint16_t id)
178 {
179 	uint32_t name_len, val_len;
180 	uint8_t *val;
181 
182 	if (!c->request_started) {
183 		log_warn("FCGI_PARAMS without FCGI_BEGIN_REQUEST, ignoring");
184 		return;
185 	}
186 
187 	if (c->id != id) {
188 		log_warn("unexpected id, ignoring");
189 		return;
190 	}
191 
192 	if (n == 0) {
193 		gotweb_process_request(c);
194 		template_flush(c->tp);
195 		return;
196 	}
197 
198 	while (n > 0) {
199 		if (buf[0] >> 7 == 0) {
200 			name_len = buf[0];
201 			n--;
202 			buf++;
203 		} else {
204 			if (n > 3) {
205 				name_len = ((buf[0] & 0x7f) << 24) +
206 				    (buf[1] << 16) + (buf[2] << 8) + buf[3];
207 				n -= 4;
208 				buf += 4;
209 			} else
210 				return;
211 		}
212 
213 		if (n == 0)
214 			return;
215 
216 		if (buf[0] >> 7 == 0) {
217 			val_len = buf[0];
218 			n--;
219 			buf++;
220 		} else {
221 			if (n > 3) {
222 				val_len = ((buf[0] & 0x7f) << 24) +
223 					(buf[1] << 16) + (buf[2] << 8) +
224 					buf[3];
225 				n -= 4;
226 				buf += 4;
227 			} else
228 				return;
229 		}
230 
231 		if (n < name_len + val_len)
232 			return;
233 
234 		val = buf + name_len;
235 
236 		if (c->querystring[0] == '\0' &&
237 		    val_len < MAX_QUERYSTRING &&
238 		    name_len == 12 &&
239 		    strncmp(buf, "QUERY_STRING", 12) == 0) {
240 			memcpy(c->querystring, val, val_len);
241 			c->querystring[val_len] = '\0';
242 		}
243 
244 		if (c->document_uri[0] == '\0' &&
245 		    val_len < MAX_DOCUMENT_URI &&
246 		    name_len == 12 &&
247 		    strncmp(buf, "DOCUMENT_URI", 12) == 0) {
248 			memcpy(c->document_uri, val, val_len);
249 			c->document_uri[val_len] = '\0';
250 		}
251 
252 		if (c->server_name[0] == '\0' &&
253 		    val_len < MAX_SERVER_NAME &&
254 		    name_len == 11 &&
255 		    strncmp(buf, "SERVER_NAME", 11) == 0) {
256 			memcpy(c->server_name, val, val_len);
257 			c->server_name[val_len] = '\0';
258 		}
259 
260 		if (name_len == 5 &&
261 		    strncmp(buf, "HTTPS", 5) == 0)
262 			c->https = 1;
263 
264 		buf += name_len + val_len;
265 		n -= name_len - val_len;
266 	}
267 }
268 
269 void
270 fcgi_timeout(int fd, short events, void *arg)
271 {
272 	fcgi_cleanup_request((struct request*) arg);
273 }
274 
275 static int
276 send_response(struct request *c, int type, const uint8_t *data,
277     size_t len)
278 {
279 	static const uint8_t padding[FCGI_PADDING_SIZE];
280 	struct fcgi_record_header header;
281 	struct iovec iov[3];
282 	struct timespec ts;
283 	ssize_t nw;
284 	size_t padded_len, tot;
285 	int i, err = 0, th = 2000;
286 
287 	ts.tv_sec = 0;
288 	ts.tv_nsec = 50;
289 
290 	memset(&header, 0, sizeof(header));
291 	header.version = 1;
292 	header.type = type;
293 	header.id = htons(c->id);
294 	header.content_len = htons(len);
295 
296 	/* The FastCGI spec suggests to align the output buffer */
297 	tot = sizeof(header) + len;
298 	padded_len = FCGI_ALIGN(tot);
299 	if (padded_len > tot) {
300 		header.padding_len = padded_len - tot;
301 		tot += header.padding_len;
302 	}
303 
304 	iov[0].iov_base = &header;
305 	iov[0].iov_len = sizeof(header);
306 
307 	iov[1].iov_base = (void *)data;
308 	iov[1].iov_len = len;
309 
310 	iov[2].iov_base = (void *)padding;
311 	iov[2].iov_len = header.padding_len;
312 
313 	dump_fcgi_record("resp ", &header);
314 
315 	/*
316 	 * XXX: add some simple write heuristics here
317 	 * On slower VMs, spotty connections, etc., we don't want to go right to
318 	 * disconnect. Let's at least try to write the data a few times before
319 	 * giving up.
320 	 */
321 	while (tot > 0) {
322 		nw = writev(c->fd, iov, nitems(iov));
323 		if (nw == 0) {
324 			c->sock->client_status = CLIENT_DISCONNECT;
325 			break;
326 		}
327 		if (nw == -1) {
328 			err++;
329 			if (errno == EAGAIN && err < th) {
330 				nanosleep(&ts, NULL);
331 				continue;
332 			}
333 			log_debug("%s: write failure: %s", __func__,
334 			    strerror(errno));
335 			c->sock->client_status = CLIENT_DISCONNECT;
336 			return -1;
337 		}
338 
339 		if (nw != tot)
340 			log_debug("%s: partial write: %zu vs %zu", __func__,
341 			    nw, tot);
342 
343 		tot -= nw;
344 		for (i = 0; i < nitems(iov); ++i) {
345 			if (nw < iov[i].iov_len) {
346 				iov[i].iov_base += nw;
347 				iov[i].iov_len -= nw;
348 				break;
349 			}
350 			nw -= iov[i].iov_len;
351 			iov[i].iov_len = 0;
352 		}
353 	}
354 
355 	return 0;
356 }
357 
358 int
359 fcgi_send_response(struct request *c, int type, const void *data,
360     size_t len)
361 {
362 	if (c->sock->client_status == CLIENT_DISCONNECT)
363 		return -1;
364 
365 	while (len > FCGI_CONTENT_SIZE) {
366 		if (send_response(c, type, data, len) == -1)
367 			return -1;
368 
369 		data += FCGI_CONTENT_SIZE;
370 		len -= FCGI_CONTENT_SIZE;
371 	}
372 
373 	if (len == 0)
374 		return 0;
375 
376 	return send_response(c, type, data, len);
377 }
378 
379 int
380 fcgi_write(void *arg, const void *buf, size_t len)
381 {
382 	struct request	*c = arg;
383 
384 	return fcgi_send_response(c, FCGI_STDOUT, buf, len);
385 }
386 
387 void
388 fcgi_create_end_record(struct request *c)
389 {
390 	struct fcgi_end_request_body end_request;
391 
392 	memset(&end_request, 0, sizeof(end_request));
393 	end_request.app_status = htonl(0); /* script status */
394 	end_request.protocol_status = FCGI_REQUEST_COMPLETE;
395 
396 	fcgi_send_response(c, FCGI_END_REQUEST, &end_request,
397 	    sizeof(end_request));
398 }
399 
400 void
401 fcgi_cleanup_request(struct request *c)
402 {
403 	cgi_inflight--;
404 	client_cnt--;
405 
406 	evtimer_del(&c->tmo);
407 	if (event_initialized(&c->ev))
408 		event_del(&c->ev);
409 
410 	close(c->fd);
411 	template_free(c->tp);
412 	if (c->t != NULL)
413 		gotweb_free_transport(c->t);
414 	free(c);
415 }
416 
417 void
418 dump_fcgi_record(const char *p, struct fcgi_record_header *h)
419 {
420 	dump_fcgi_record_header(p, h);
421 
422 	if (h->type == FCGI_BEGIN_REQUEST)
423 		dump_fcgi_begin_request_body(p,
424 		    (struct fcgi_begin_request_body *)(h + 1));
425 	else if (h->type == FCGI_END_REQUEST)
426 		dump_fcgi_end_request_body(p,
427 		    (struct fcgi_end_request_body *)(h + 1));
428 }
429 
430 void
431 dump_fcgi_record_header(const char* p, struct fcgi_record_header *h)
432 {
433 	log_debug("%sversion:         %d", p, h->version);
434 	log_debug("%stype:            %d", p, h->type);
435 	log_debug("%srequestId:       %d", p, ntohs(h->id));
436 	log_debug("%scontentLength:   %d", p, ntohs(h->content_len));
437 	log_debug("%spaddingLength:   %d", p, h->padding_len);
438 	log_debug("%sreserved:        %d", p, h->reserved);
439 }
440 
441 void
442 dump_fcgi_begin_request_body(const char *p, struct fcgi_begin_request_body *b)
443 {
444 	log_debug("%srole             %d", p, ntohs(b->role));
445 	log_debug("%sflags            %d", p, b->flags);
446 }
447 
448 void
449 dump_fcgi_end_request_body(const char *p, struct fcgi_end_request_body *b)
450 {
451 	log_debug("%sappStatus:       %d", p, ntohl(b->app_status));
452 	log_debug("%sprotocolStatus:  %d", p, b->protocol_status);
453 }