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