accf_http.c revision 172467 
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: head/sys/netinet/accf_http.c 172467 2007-10-07 20:44:24Z silby $");
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 void sohashttpget(struct socket *so, void *arg, int waitflag);
43/* check for HTTP/1.0 or HTTP/1.1 */
44static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
45/* check for end of HTTP/1.x request */
46static void 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
72SYSCTL_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 (sb->sb_cc >= 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 void
162sohashttpget(struct socket *so, void *arg, int waitflag)
163{
164
165	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
166		struct mbuf *m;
167		char *cmp;
168		int	cmplen, cc;
169
170		m = so->so_rcv.sb_mb;
171		cc = so->so_rcv.sb_cc - 1;
172		if (cc < 1)
173			return;
174		switch (*mtod(m, char *)) {
175		case 'G':
176			STRSETUP(cmp, cmplen, "ET ");
177			break;
178		case 'H':
179			STRSETUP(cmp, cmplen, "EAD ");
180			break;
181		default:
182			goto fallout;
183		}
184		if (cc < cmplen) {
185			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
186				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
187				return;
188			} else {
189				DPRINT("short cc (%d) mbufstrncmp failed", cc);
190				goto fallout;
191			}
192		}
193		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
194			DPRINT("mbufstrcmp ok");
195			if (parse_http_version == 0)
196				soishttpconnected(so, arg, waitflag);
197			else
198				soparsehttpvers(so, arg, waitflag);
199			return;
200		}
201		DPRINT("mbufstrcmp bad");
202	}
203
204fallout:
205	DPRINT("fallout");
206	so->so_upcall = NULL;
207	so->so_rcv.sb_flags &= ~SB_UPCALL;
208	soisconnected(so);
209	return;
210}
211
212static void
213soparsehttpvers(struct socket *so, void *arg, int waitflag)
214{
215	struct mbuf *m, *n;
216	int	i, cc, spaces, inspaces;
217
218	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
219		goto fallout;
220
221	m = so->so_rcv.sb_mb;
222	cc = so->so_rcv.sb_cc;
223	inspaces = spaces = 0;
224	for (m = so->so_rcv.sb_mb; m; m = n) {
225		n = m->m_nextpkt;
226		for (; m; m = m->m_next) {
227			for (i = 0; i < m->m_len; i++, cc--) {
228				switch (*(mtod(m, char *) + i)) {
229				case ' ':
230					/* tabs? '\t' */
231					if (!inspaces) {
232						spaces++;
233						inspaces = 1;
234					}
235					break;
236				case '\r':
237				case '\n':
238					DPRINT("newline");
239					goto fallout;
240				default:
241					if (spaces != 2) {
242						inspaces = 0;
243						break;
244					}
245
246					/*
247					 * if we don't have enough characters
248					 * left (cc < sizeof("HTTP/1.0") - 1)
249					 * then see if the remaining ones
250					 * are a request we can parse.
251					 */
252					if (cc < sizeof("HTTP/1.0") - 1) {
253						if (mbufstrncmp(m, n, i, cc,
254							"HTTP/1.") == 1) {
255							DPRINT("ok");
256							goto readmore;
257						} else {
258							DPRINT("bad");
259							goto fallout;
260						}
261					} else if (
262					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
263					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
264							DPRINT("ok");
265							soishttpconnected(so,
266							    arg, waitflag);
267							return;
268					} else {
269						DPRINT("bad");
270						goto fallout;
271					}
272				}
273			}
274		}
275	}
276readmore:
277	DPRINT("readmore");
278	/*
279	 * if we hit here we haven't hit something
280	 * we don't understand or a newline, so try again
281	 */
282	so->so_upcall = soparsehttpvers;
283	so->so_rcv.sb_flags |= SB_UPCALL;
284	return;
285
286fallout:
287	DPRINT("fallout");
288	so->so_upcall = NULL;
289	so->so_rcv.sb_flags &= ~SB_UPCALL;
290	soisconnected(so);
291	return;
292}
293
294
295#define NCHRS 3
296
297static void
298soishttpconnected(struct socket *so, void *arg, int waitflag)
299{
300	char a, b, c;
301	struct mbuf *m, *n;
302	int ccleft, copied;
303
304	DPRINT("start");
305	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
306		goto gotit;
307
308	/*
309	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
310	 * copied - how much we've copied so far
311	 * ccleft - how many bytes remaining in the socketbuffer
312	 * just loop over the mbufs subtracting from 'ccleft' until we only
313	 * have NCHRS left
314	 */
315	copied = 0;
316	ccleft = so->so_rcv.sb_cc;
317	if (ccleft < NCHRS)
318		goto readmore;
319	a = b = c = '\0';
320	for (m = so->so_rcv.sb_mb; m; m = n) {
321		n = m->m_nextpkt;
322		for (; m; m = m->m_next) {
323			ccleft -= m->m_len;
324			if (ccleft <= NCHRS) {
325				char *src;
326				int tocopy;
327
328				tocopy = (NCHRS - ccleft) - copied;
329				src = mtod(m, char *) + (m->m_len - tocopy);
330
331				while (tocopy--) {
332					switch (copied++) {
333					case 0:
334						a = *src++;
335						break;
336					case 1:
337						b = *src++;
338						break;
339					case 2:
340						c = *src++;
341						break;
342					}
343				}
344			}
345		}
346	}
347	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
348		/* we have all request headers */
349		goto gotit;
350	}
351
352readmore:
353	so->so_upcall = soishttpconnected;
354	so->so_rcv.sb_flags |= SB_UPCALL;
355	return;
356
357gotit:
358	so->so_upcall = NULL;
359	so->so_rcv.sb_flags &= ~SB_UPCALL;
360	soisconnected(so);
361	return;
362}
363