accf_http.c revision 70643 
1214501Srpaulo/*
2214501Srpaulo * Copyright (c) 2000 Paycounter, Inc.
3214501Srpaulo * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
4214501Srpaulo * All rights reserved.
5214501Srpaulo *
6214501Srpaulo * Redistribution and use in source and binary forms, with or without
7214501Srpaulo * modification, are permitted provided that the following conditions
8214501Srpaulo * are met:
9214501Srpaulo * 1. Redistributions of source code must retain the above copyright
10214501Srpaulo *    notice, this list of conditions and the following disclaimer.
11214501Srpaulo * 2. Redistributions in binary form must reproduce the above copyright
12214501Srpaulo *    notice, this list of conditions and the following disclaimer in the
13214501Srpaulo *    documentation and/or other materials provided with the distribution.
14214501Srpaulo *
15214501Srpaulo * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16214501Srpaulo * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17214501Srpaulo * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18214501Srpaulo * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19214501Srpaulo * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20214501Srpaulo * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21214501Srpaulo * 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 70643 2001-01-03 19:50:23Z alfred $
28 */
29
30#define ACCEPT_FILTER_MOD
31
32#include <sys/param.h>
33#include <sys/kernel.h>
34#include <sys/sysctl.h>
35#include <sys/socketvar.h>
36#include <sys/mbuf.h>
37
38/* check for GET/HEAD */
39static void sohashttpget(struct socket *so, void *arg, int waitflag);
40/* check for HTTP/1.0 or HTTP/1.1 */
41static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
42/* check for end of HTTP/1.x request */
43static void soishttpconnected(struct socket *so, void *arg, int waitflag);
44/* strcmp on an mbuf chain */
45static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
46/* strncmp on an mbuf chain */
47static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
48	int max, char *cmp);
49/* socketbuffer is full */
50static int sbfull(struct sockbuf *sb);
51
52static struct accept_filter accf_http_filter = {
53	"httpready",
54	sohashttpget,
55	NULL,
56	NULL
57};
58
59static moduledata_t accf_http_mod = {
60	"accf_http",
61	accept_filt_generic_mod_event,
62	&accf_http_filter
63};
64
65DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
66
67static int parse_http_version = 1;
68
69SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
70"HTTP accept filter");
71SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
72&parse_http_version, 1,
73"Parse http version so that non 1.x requests work");
74
75#ifdef ACCF_HTTP_DEBUG
76#define DPRINT(fmt, args...) \
77	do {	\
78		printf("%s:%d: " fmt "\n", __func__, __LINE__ , ##args);	\
79	} while (0)
80#else
81#define DPRINT(fmt, args...)
82#endif
83
84static int
85sbfull(struct sockbuf *sb)
86{
87
88	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, mbcnt(%ld) >= mbmax(%ld): %d",
89		sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
90		sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
91	return(sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
92}
93
94/*
95 * start at mbuf m, (must provide npkt if exists)
96 * starting at offset in m compare characters in mbuf chain for 'cmp'
97 */
98static int
99mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
100{
101	struct mbuf *n;
102
103	for (;m != NULL; m = n) {
104		n = npkt;
105		if (npkt)
106			npkt = npkt->m_nextpkt;
107		for (; m; m = m->m_next) {
108			for (; offset < m->m_len; offset++, cmp++) {
109				if (*cmp == '\0') {
110					return (1);
111				} else if (*cmp != *(mtod(m, char *) + offset)) {
112					return (0);
113				}
114			}
115			offset = 0;
116		}
117	}
118	return (0);
119}
120
121/*
122 * start at mbuf m, (must provide npkt if exists)
123 * starting at offset in m compare characters in mbuf chain for 'cmp'
124 * stop at 'max' characters
125 */
126static int
127mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
128{
129	struct mbuf *n;
130
131	for (;m != NULL; m = n) {
132		n = npkt;
133		if (npkt)
134			npkt = npkt->m_nextpkt;
135		for (; m; m = m->m_next) {
136			for (; offset < m->m_len; offset++, cmp++, max--) {
137				if (max == 0 || *cmp == '\0') {
138					return (1);
139				} else if (*cmp != *(mtod(m, char *) + offset)) {
140					return (0);
141				}
142			}
143			offset = 0;
144		}
145	}
146	return (0);
147}
148
149#define STRSETUP(sptr, slen, str) \
150	do {	\
151		sptr = str;	\
152		slen = sizeof(str) - 1;	\
153	} while(0)
154
155static void
156sohashttpget(struct socket *so, void *arg, int waitflag)
157{
158
159	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
160		struct mbuf *m;
161		char *cmp;
162		int	cmplen, cc;
163
164		m = so->so_rcv.sb_mb;
165		cc = so->so_rcv.sb_cc - 1;
166		if (cc < 1)
167			return;
168		switch (*mtod(m, char *)) {
169		case 'G':
170			STRSETUP(cmp, cmplen, "ET ");
171			break;
172		case 'H':
173			STRSETUP(cmp, cmplen, "EAD ");
174			break;
175		default:
176			goto fallout;
177		}
178		if (cc < cmplen) {
179			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
180				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
181				return;
182			} else {
183				DPRINT("short cc (%d) mbufstrncmp failed", cc);
184				goto fallout;
185			}
186		}
187		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
188			DPRINT("mbufstrcmp ok");
189			if (parse_http_version == 0)
190				soishttpconnected(so, arg, waitflag);
191			else
192				soparsehttpvers(so, arg, waitflag);
193			return;
194		}
195		DPRINT("mbufstrcmp bad");
196	}
197
198fallout:
199	DPRINT("fallout");
200	so->so_upcall = NULL;
201	so->so_rcv.sb_flags &= ~SB_UPCALL;
202	soisconnected(so);
203	return;
204}
205
206static void
207soparsehttpvers(struct socket *so, void *arg, int waitflag)
208{
209	struct mbuf *m, *n;
210	int	i, cc, spaces, inspaces;
211
212	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
213		goto fallout;
214
215	m = so->so_rcv.sb_mb;
216	cc = so->so_rcv.sb_cc;
217	inspaces = spaces = 0;
218	for (m = so->so_rcv.sb_mb; m; m = n) {
219		n = m->m_nextpkt;
220		for (; m; m = m->m_next) {
221			for (i = 0; i < m->m_len; i++, cc--) {
222				switch (*(mtod(m, char *) + i)) {
223				case ' ':
224					if (!inspaces) {
225						spaces++;
226						inspaces = 1;
227					}
228					break;
229				case '\r':
230				case '\n':
231					DPRINT("newline");
232					goto fallout;
233				default:
234					if (spaces == 2) {
235						/* make sure we have enough data left */
236						if (cc < sizeof("HTTP/1.0") - 1) {
237							if (mbufstrncmp(m, n, i, cc, "HTTP/1.") == 1) {
238								DPRINT("mbufstrncmp ok");
239								goto readmore;
240							} else {
241								DPRINT("mbufstrncmp bad");
242								goto fallout;
243							}
244						} else if (mbufstrcmp(m, n, i, "HTTP/1.0") == 1 ||
245									mbufstrcmp(m, n, i, "HTTP/1.1") == 1) {
246								DPRINT("mbufstrcmp ok");
247								soishttpconnected(so, arg, waitflag);
248								return;
249						} else {
250							DPRINT("mbufstrcmp bad");
251							goto fallout;
252						}
253					}
254					inspaces = 0;
255					break;
256				}
257			}
258		}
259	}
260readmore:
261	DPRINT("readmore");
262	/*
263	 * if we hit here we haven't hit something
264	 * we don't understand or a newline, so try again
265	 */
266	so->so_upcall = soparsehttpvers;
267	so->so_rcv.sb_flags |= SB_UPCALL;
268	return;
269
270fallout:
271	DPRINT("fallout");
272	so->so_upcall = NULL;
273	so->so_rcv.sb_flags &= ~SB_UPCALL;
274	soisconnected(so);
275	return;
276}
277
278
279#define NCHRS 3
280
281static void
282soishttpconnected(struct socket *so, void *arg, int waitflag)
283{
284	char a, b, c;
285	struct mbuf *m, *n;
286	int ccleft, copied;
287
288	DPRINT("start");
289	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
290		goto gotit;
291
292	/*
293	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
294	 * copied - how much we've copied so far
295	 * ccleft - how many bytes remaining in the socketbuffer
296	 * just loop over the mbufs subtracting from 'ccleft' until we only
297	 * have NCHRS left
298	 */
299	copied = 0;
300	ccleft = so->so_rcv.sb_cc;
301	if (ccleft < NCHRS)
302		goto readmore;
303	a = b = c = '\0';
304	for (m = so->so_rcv.sb_mb; m; m = n) {
305		n = m->m_nextpkt;
306		for (; m; m = m->m_next) {
307			ccleft -= m->m_len;
308			if (ccleft <= NCHRS) {
309				char *src;
310				int tocopy;
311
312				tocopy = (NCHRS - ccleft) - copied;
313				src = mtod(m, char *) + (m->m_len - tocopy);
314
315				while (tocopy--) {
316					switch (copied++) {
317					case 0:
318						a = *src++;
319						break;
320					case 1:
321						b = *src++;
322						break;
323					case 2:
324						c = *src++;
325						break;
326					}
327				}
328			}
329		}
330	}
331	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
332		/* we have all request headers */
333		goto gotit;
334	}
335
336readmore:
337	so->so_upcall = soishttpconnected;
338	so->so_rcv.sb_flags |= SB_UPCALL;
339	return;
340
341gotit:
342	so->so_upcall = NULL;
343	so->so_rcv.sb_flags &= ~SB_UPCALL;
344	soisconnected(so);
345	return;
346}
347