accf_http.c revision 139823 
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 *	$FreeBSD: head/sys/netinet/accf_http.c 139823 2005-01-07 01:45:51Z imp $
28 */
29
30#define ACCEPT_FILTER_MOD
31
32#include <sys/param.h>
33#include <sys/kernel.h>
34#include <sys/mbuf.h>
35#include <sys/module.h>
36#include <sys/signalvar.h>
37#include <sys/sysctl.h>
38#include <sys/socketvar.h>
39
40/* check for GET/HEAD */
41static void sohashttpget(struct socket *so, void *arg, int waitflag);
42/* check for HTTP/1.0 or HTTP/1.1 */
43static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
44/* check for end of HTTP/1.x request */
45static void soishttpconnected(struct socket *so, void *arg, int waitflag);
46/* strcmp on an mbuf chain */
47static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
48/* strncmp on an mbuf chain */
49static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
50	int max, char *cmp);
51/* socketbuffer is full */
52static int sbfull(struct sockbuf *sb);
53
54static struct accept_filter accf_http_filter = {
55	"httpready",
56	sohashttpget,
57	NULL,
58	NULL
59};
60
61static moduledata_t accf_http_mod = {
62	"accf_http",
63	accept_filt_generic_mod_event,
64	&accf_http_filter
65};
66
67DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
68
69static int parse_http_version = 1;
70
71SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
72"HTTP accept filter");
73SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
74&parse_http_version, 1,
75"Parse http version so that non 1.x requests work");
76
77#ifdef ACCF_HTTP_DEBUG
78#define DPRINT(fmt, args...)						\
79	do {								\
80		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
81	} while (0)
82#else
83#define DPRINT(fmt, args...)
84#endif
85
86static int
87sbfull(struct sockbuf *sb)
88{
89
90	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
91	    "mbcnt(%ld) >= mbmax(%ld): %d",
92	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
93	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
94	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
95}
96
97/*
98 * start at mbuf m, (must provide npkt if exists)
99 * starting at offset in m compare characters in mbuf chain for 'cmp'
100 */
101static int
102mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
103{
104	struct mbuf *n;
105
106	for (; m != NULL; m = n) {
107		n = npkt;
108		if (npkt)
109			npkt = npkt->m_nextpkt;
110		for (; m; m = m->m_next) {
111			for (; offset < m->m_len; offset++, cmp++) {
112				if (*cmp == '\0')
113					return (1);
114				else if (*cmp != *(mtod(m, char *) + offset))
115					return (0);
116			}
117			if (*cmp == '\0')
118				return (1);
119			offset = 0;
120		}
121	}
122	return (0);
123}
124
125/*
126 * start at mbuf m, (must provide npkt if exists)
127 * starting at offset in m compare characters in mbuf chain for 'cmp'
128 * stop at 'max' characters
129 */
130static int
131mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
132{
133	struct mbuf *n;
134
135	for (; m != NULL; m = n) {
136		n = npkt;
137		if (npkt)
138			npkt = npkt->m_nextpkt;
139		for (; m; m = m->m_next) {
140			for (; offset < m->m_len; offset++, cmp++, max--) {
141				if (max == 0 || *cmp == '\0')
142					return (1);
143				else if (*cmp != *(mtod(m, char *) + offset))
144					return (0);
145			}
146			if (max == 0 || *cmp == '\0')
147				return (1);
148			offset = 0;
149		}
150	}
151	return (0);
152}
153
154#define STRSETUP(sptr, slen, str)					\
155	do {								\
156		sptr = str;						\
157		slen = sizeof(str) - 1;					\
158	} while(0)
159
160static void
161sohashttpget(struct socket *so, void *arg, int waitflag)
162{
163
164	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
165		struct mbuf *m;
166		char *cmp;
167		int	cmplen, cc;
168
169		m = so->so_rcv.sb_mb;
170		cc = so->so_rcv.sb_cc - 1;
171		if (cc < 1)
172			return;
173		switch (*mtod(m, char *)) {
174		case 'G':
175			STRSETUP(cmp, cmplen, "ET ");
176			break;
177		case 'H':
178			STRSETUP(cmp, cmplen, "EAD ");
179			break;
180		default:
181			goto fallout;
182		}
183		if (cc < cmplen) {
184			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
185				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
186				return;
187			} else {
188				DPRINT("short cc (%d) mbufstrncmp failed", cc);
189				goto fallout;
190			}
191		}
192		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
193			DPRINT("mbufstrcmp ok");
194			if (parse_http_version == 0)
195				soishttpconnected(so, arg, waitflag);
196			else
197				soparsehttpvers(so, arg, waitflag);
198			return;
199		}
200		DPRINT("mbufstrcmp bad");
201	}
202
203fallout:
204	DPRINT("fallout");
205	so->so_upcall = NULL;
206	so->so_rcv.sb_flags &= ~SB_UPCALL;
207	soisconnected(so);
208	return;
209}
210
211static void
212soparsehttpvers(struct socket *so, void *arg, int waitflag)
213{
214	struct mbuf *m, *n;
215	int	i, cc, spaces, inspaces;
216
217	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
218		goto fallout;
219
220	m = so->so_rcv.sb_mb;
221	cc = so->so_rcv.sb_cc;
222	inspaces = spaces = 0;
223	for (m = so->so_rcv.sb_mb; m; m = n) {
224		n = m->m_nextpkt;
225		for (; m; m = m->m_next) {
226			for (i = 0; i < m->m_len; i++, cc--) {
227				switch (*(mtod(m, char *) + i)) {
228				case ' ':
229					/* tabs? '\t' */
230					if (!inspaces) {
231						spaces++;
232						inspaces = 1;
233					}
234					break;
235				case '\r':
236				case '\n':
237					DPRINT("newline");
238					goto fallout;
239				default:
240					if (spaces != 2) {
241						inspaces = 0;
242						break;
243					}
244
245					/*
246					 * if we don't have enough characters
247					 * left (cc < sizeof("HTTP/1.0") - 1)
248					 * then see if the remaining ones
249					 * are a request we can parse.
250					 */
251					if (cc < sizeof("HTTP/1.0") - 1) {
252						if (mbufstrncmp(m, n, i, cc,
253							"HTTP/1.") == 1) {
254							DPRINT("ok");
255							goto readmore;
256						} else {
257							DPRINT("bad");
258							goto fallout;
259						}
260					} else if (
261					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
262					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
263							DPRINT("ok");
264							soishttpconnected(so,
265							    arg, waitflag);
266							return;
267					} else {
268						DPRINT("bad");
269						goto fallout;
270					}
271				}
272			}
273		}
274	}
275readmore:
276	DPRINT("readmore");
277	/*
278	 * if we hit here we haven't hit something
279	 * we don't understand or a newline, so try again
280	 */
281	so->so_upcall = soparsehttpvers;
282	so->so_rcv.sb_flags |= SB_UPCALL;
283	return;
284
285fallout:
286	DPRINT("fallout");
287	so->so_upcall = NULL;
288	so->so_rcv.sb_flags &= ~SB_UPCALL;
289	soisconnected(so);
290	return;
291}
292
293
294#define NCHRS 3
295
296static void
297soishttpconnected(struct socket *so, void *arg, int waitflag)
298{
299	char a, b, c;
300	struct mbuf *m, *n;
301	int ccleft, copied;
302
303	DPRINT("start");
304	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
305		goto gotit;
306
307	/*
308	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
309	 * copied - how much we've copied so far
310	 * ccleft - how many bytes remaining in the socketbuffer
311	 * just loop over the mbufs subtracting from 'ccleft' until we only
312	 * have NCHRS left
313	 */
314	copied = 0;
315	ccleft = so->so_rcv.sb_cc;
316	if (ccleft < NCHRS)
317		goto readmore;
318	a = b = c = '\0';
319	for (m = so->so_rcv.sb_mb; m; m = n) {
320		n = m->m_nextpkt;
321		for (; m; m = m->m_next) {
322			ccleft -= m->m_len;
323			if (ccleft <= NCHRS) {
324				char *src;
325				int tocopy;
326
327				tocopy = (NCHRS - ccleft) - copied;
328				src = mtod(m, char *) + (m->m_len - tocopy);
329
330				while (tocopy--) {
331					switch (copied++) {
332					case 0:
333						a = *src++;
334						break;
335					case 1:
336						b = *src++;
337						break;
338					case 2:
339						c = *src++;
340						break;
341					}
342				}
343			}
344		}
345	}
346	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
347		/* we have all request headers */
348		goto gotit;
349	}
350
351readmore:
352	so->so_upcall = soishttpconnected;
353	so->so_rcv.sb_flags |= SB_UPCALL;
354	return;
355
356gotit:
357	so->so_upcall = NULL;
358	so->so_rcv.sb_flags &= ~SB_UPCALL;
359	soisconnected(so);
360	return;
361}
362