1/*-
2 * Copyright (c) 2000 Paycounter, Inc.
3 * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD$");
30
31#define ACCEPT_FILTER_MOD
32
33#include <sys/param.h>
34#include <sys/kernel.h>
35#include <sys/mbuf.h>
36#include <sys/module.h>
37#include <sys/signalvar.h>
38#include <sys/sysctl.h>
39#include <sys/socketvar.h>
40
41/* check for GET/HEAD */
42static int sohashttpget(struct socket *so, void *arg, int waitflag);
43/* check for HTTP/1.0 or HTTP/1.1 */
44static int soparsehttpvers(struct socket *so, void *arg, int waitflag);
45/* check for end of HTTP/1.x request */
46static int soishttpconnected(struct socket *so, void *arg, int waitflag);
47/* strcmp on an mbuf chain */
48static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
49/* strncmp on an mbuf chain */
50static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
51	int max, char *cmp);
52/* socketbuffer is full */
53static int sbfull(struct sockbuf *sb);
54
55static struct accept_filter accf_http_filter = {
56	"httpready",
57	sohashttpget,
58	NULL,
59	NULL
60};
61
62static moduledata_t accf_http_mod = {
63	"accf_http",
64	accept_filt_generic_mod_event,
65	&accf_http_filter
66};
67
68DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
69
70static int parse_http_version = 1;
71
72static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
73"HTTP accept filter");
74SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
75&parse_http_version, 1,
76"Parse http version so that non 1.x requests work");
77
78#ifdef ACCF_HTTP_DEBUG
79#define DPRINT(fmt, args...)						\
80	do {								\
81		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
82	} while (0)
83#else
84#define DPRINT(fmt, args...)
85#endif
86
87static int
88sbfull(struct sockbuf *sb)
89{
90
91	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
92	    "mbcnt(%ld) >= mbmax(%ld): %d",
93	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
94	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
95	return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
96}
97
98/*
99 * start at mbuf m, (must provide npkt if exists)
100 * starting at offset in m compare characters in mbuf chain for 'cmp'
101 */
102static int
103mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
104{
105	struct mbuf *n;
106
107	for (; m != NULL; m = n) {
108		n = npkt;
109		if (npkt)
110			npkt = npkt->m_nextpkt;
111		for (; m; m = m->m_next) {
112			for (; offset < m->m_len; offset++, cmp++) {
113				if (*cmp == '\0')
114					return (1);
115				else if (*cmp != *(mtod(m, char *) + offset))
116					return (0);
117			}
118			if (*cmp == '\0')
119				return (1);
120			offset = 0;
121		}
122	}
123	return (0);
124}
125
126/*
127 * start at mbuf m, (must provide npkt if exists)
128 * starting at offset in m compare characters in mbuf chain for 'cmp'
129 * stop at 'max' characters
130 */
131static int
132mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
133{
134	struct mbuf *n;
135
136	for (; m != NULL; m = n) {
137		n = npkt;
138		if (npkt)
139			npkt = npkt->m_nextpkt;
140		for (; m; m = m->m_next) {
141			for (; offset < m->m_len; offset++, cmp++, max--) {
142				if (max == 0 || *cmp == '\0')
143					return (1);
144				else if (*cmp != *(mtod(m, char *) + offset))
145					return (0);
146			}
147			if (max == 0 || *cmp == '\0')
148				return (1);
149			offset = 0;
150		}
151	}
152	return (0);
153}
154
155#define STRSETUP(sptr, slen, str)					\
156	do {								\
157		sptr = str;						\
158		slen = sizeof(str) - 1;					\
159	} while(0)
160
161static int
162sohashttpget(struct socket *so, void *arg, int waitflag)
163{
164
165	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 &&
166	    !sbfull(&so->so_rcv)) {
167		struct mbuf *m;
168		char *cmp;
169		int	cmplen, cc;
170
171		m = so->so_rcv.sb_mb;
172		cc = sbavail(&so->so_rcv) - 1;
173		if (cc < 1)
174			return (SU_OK);
175		switch (*mtod(m, char *)) {
176		case 'G':
177			STRSETUP(cmp, cmplen, "ET ");
178			break;
179		case 'H':
180			STRSETUP(cmp, cmplen, "EAD ");
181			break;
182		default:
183			goto fallout;
184		}
185		if (cc < cmplen) {
186			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
187				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
188				return (SU_OK);
189			} else {
190				DPRINT("short cc (%d) mbufstrncmp failed", cc);
191				goto fallout;
192			}
193		}
194		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
195			DPRINT("mbufstrcmp ok");
196			if (parse_http_version == 0)
197				return (soishttpconnected(so, arg, waitflag));
198			else
199				return (soparsehttpvers(so, arg, waitflag));
200		}
201		DPRINT("mbufstrcmp bad");
202	}
203
204fallout:
205	DPRINT("fallout");
206	return (SU_ISCONNECTED);
207}
208
209static int
210soparsehttpvers(struct socket *so, void *arg, int waitflag)
211{
212	struct mbuf *m, *n;
213	int	i, cc, spaces, inspaces;
214
215	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
216		goto fallout;
217
218	m = so->so_rcv.sb_mb;
219	cc = sbavail(&so->so_rcv);
220	inspaces = spaces = 0;
221	for (m = so->so_rcv.sb_mb; m; m = n) {
222		n = m->m_nextpkt;
223		for (; m; m = m->m_next) {
224			for (i = 0; i < m->m_len; i++, cc--) {
225				switch (*(mtod(m, char *) + i)) {
226				case ' ':
227					/* tabs? '\t' */
228					if (!inspaces) {
229						spaces++;
230						inspaces = 1;
231					}
232					break;
233				case '\r':
234				case '\n':
235					DPRINT("newline");
236					goto fallout;
237				default:
238					if (spaces != 2) {
239						inspaces = 0;
240						break;
241					}
242
243					/*
244					 * if we don't have enough characters
245					 * left (cc < sizeof("HTTP/1.0") - 1)
246					 * then see if the remaining ones
247					 * are a request we can parse.
248					 */
249					if (cc < sizeof("HTTP/1.0") - 1) {
250						if (mbufstrncmp(m, n, i, cc,
251							"HTTP/1.") == 1) {
252							DPRINT("ok");
253							goto readmore;
254						} else {
255							DPRINT("bad");
256							goto fallout;
257						}
258					} else if (
259					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
260					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
261						DPRINT("ok");
262						return (soishttpconnected(so,
263						    arg, waitflag));
264					} else {
265						DPRINT("bad");
266						goto fallout;
267					}
268				}
269			}
270		}
271	}
272readmore:
273	DPRINT("readmore");
274	/*
275	 * if we hit here we haven't hit something
276	 * we don't understand or a newline, so try again
277	 */
278	soupcall_set(so, SO_RCV, soparsehttpvers, arg);
279	return (SU_OK);
280
281fallout:
282	DPRINT("fallout");
283	return (SU_ISCONNECTED);
284}
285
286
287#define NCHRS 3
288
289static int
290soishttpconnected(struct socket *so, void *arg, int waitflag)
291{
292	char a, b, c;
293	struct mbuf *m, *n;
294	int ccleft, copied;
295
296	DPRINT("start");
297	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
298		goto gotit;
299
300	/*
301	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
302	 * copied - how much we've copied so far
303	 * ccleft - how many bytes remaining in the socketbuffer
304	 * just loop over the mbufs subtracting from 'ccleft' until we only
305	 * have NCHRS left
306	 */
307	copied = 0;
308	ccleft = sbavail(&so->so_rcv);
309	if (ccleft < NCHRS)
310		goto readmore;
311	a = b = c = '\0';
312	for (m = so->so_rcv.sb_mb; m; m = n) {
313		n = m->m_nextpkt;
314		for (; m; m = m->m_next) {
315			ccleft -= m->m_len;
316			if (ccleft <= NCHRS) {
317				char *src;
318				int tocopy;
319
320				tocopy = (NCHRS - ccleft) - copied;
321				src = mtod(m, char *) + (m->m_len - tocopy);
322
323				while (tocopy--) {
324					switch (copied++) {
325					case 0:
326						a = *src++;
327						break;
328					case 1:
329						b = *src++;
330						break;
331					case 2:
332						c = *src++;
333						break;
334					}
335				}
336			}
337		}
338	}
339	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
340		/* we have all request headers */
341		goto gotit;
342	}
343
344readmore:
345	soupcall_set(so, SO_RCV, soishttpconnected, arg);
346	return (SU_OK);
347
348gotit:
349	return (SU_ISCONNECTED);
350}
351