accf_http.c revision 66798 
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 66798 2000-10-07 23:15:17Z alfred $
28 */
29
30#define ACCEPT_FILTER_MOD
31
32#include <sys/param.h>
33#include <sys/kernel.h>
34#include <sys/proc.h>
35#include <sys/sysctl.h>
36#include <sys/socketvar.h>
37#include <sys/mbuf.h>
38
39/* check for GET/HEAD */
40static void sohashttpget(struct socket *so, void *arg, int waitflag);
41/* check for HTTP/1.0 or HTTP/1.1 */
42static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
43/* check for end of HTTP/1.x request */
44static void soishttpconnected(struct socket *so, void *arg, int waitflag);
45/* strcmp on an mbuf chain */
46static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
47/* strncmp on an mbuf chain */
48static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
49	int max, char *cmp);
50/* socketbuffer is full */
51static int sbfull(struct sockbuf *sb);
52
53static struct accept_filter accf_http_filter = {
54	"httpready",
55	sohashttpget,
56	NULL,
57	NULL
58};
59
60static moduledata_t accf_http_mod = {
61	"accf_http",
62	accept_filt_generic_mod_event,
63	&accf_http_filter
64};
65
66DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
67
68static int parse_http_version = 1;
69
70SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
71"HTTP accept filter");
72SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
73&parse_http_version, 1,
74"Parse http version so that non 1.x requests work");
75
76#ifdef ACCF_HTTP_DEBUG
77#define DPRINT(fmt, args...) \
78	do {	\
79		printf("%s:%d: " fmt "\n", __func__, __LINE__ , ##args);	\
80	} while (0)
81#else
82#define DPRINT(fmt, args...)
83#endif
84
85static int
86sbfull(struct sockbuf *sb)
87{
88
89	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, mbcnt(%ld) >= mbmax(%ld): %d",
90		sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
91		sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
92	return(sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
93}
94
95/*
96 * start at mbuf m, (must provide npkt if exists)
97 * starting at offset in m compare characters in mbuf chain for 'cmp'
98 */
99static int
100mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
101{
102	struct mbuf *n;
103
104	for (;m != NULL; m = n) {
105		n = npkt;
106		if (npkt)
107			npkt = npkt->m_nextpkt;
108		for (; m; m = m->m_next) {
109			for (; offset < m->m_len; offset++, cmp++) {
110				if (*cmp == '\0') {
111					return (1);
112				} else if (*cmp != *(mtod(m, char *) + offset)) {
113					return (0);
114				}
115			}
116			offset = 0;
117		}
118	}
119	return (0);
120}
121
122/*
123 * start at mbuf m, (must provide npkt if exists)
124 * starting at offset in m compare characters in mbuf chain for 'cmp'
125 * stop at 'max' characters
126 */
127static int
128mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
129{
130	struct mbuf *n;
131
132	for (;m != NULL; m = n) {
133		n = npkt;
134		if (npkt)
135			npkt = npkt->m_nextpkt;
136		for (; m; m = m->m_next) {
137			for (; offset < m->m_len; offset++, cmp++, max--) {
138				if (max == 0 || *cmp == '\0') {
139					return (1);
140				} else if (*cmp != *(mtod(m, char *) + offset)) {
141					return (0);
142				}
143			}
144			offset = 0;
145		}
146	}
147	return (0);
148}
149
150#define STRSETUP(sptr, slen, str) \
151	do {	\
152		sptr = str;	\
153		slen = sizeof(str) - 1;	\
154	} while(0)
155
156static void
157sohashttpget(struct socket *so, void *arg, int waitflag)
158{
159
160	if ((so->so_state & SS_CANTRCVMORE) == 0 || !sbfull(&so->so_rcv)) {
161		struct mbuf *m;
162		char *cmp;
163		int	cmplen, cc;
164
165		m = so->so_rcv.sb_mb;
166		cc = so->so_rcv.sb_cc - 1;
167		if (cc < 1)
168			return;
169		switch (*mtod(m, char *)) {
170		case 'G':
171			STRSETUP(cmp, cmplen, "ET ");
172			break;
173		case 'H':
174			STRSETUP(cmp, cmplen, "EAD ");
175			break;
176		default:
177			goto fallout;
178		}
179		if (cc < cmplen) {
180			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
181				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
182				return;
183			} else {
184				DPRINT("short cc (%d) mbufstrncmp failed", cc);
185				goto fallout;
186			}
187		}
188		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
189			DPRINT("mbufstrcmp ok");
190			if (parse_http_version == 0)
191				soishttpconnected(so, arg, waitflag);
192			else
193				soparsehttpvers(so, arg, waitflag);
194			return;
195		}
196		DPRINT("mbufstrcmp bad");
197	}
198
199fallout:
200	DPRINT("fallout");
201	so->so_upcall = NULL;
202	so->so_rcv.sb_flags &= ~SB_UPCALL;
203	soisconnected(so);
204	return;
205}
206
207static void
208soparsehttpvers(struct socket *so, void *arg, int waitflag)
209{
210	struct mbuf *m, *n;
211	int	i, cc, spaces, inspaces;
212
213	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
214		goto fallout;
215
216	m = so->so_rcv.sb_mb;
217	cc = so->so_rcv.sb_cc;
218	inspaces = spaces = 0;
219	for (m = so->so_rcv.sb_mb; m; m = n) {
220		n = m->m_nextpkt;
221		for (; m; m = m->m_next) {
222			for (i = 0; i < m->m_len; i++, cc--) {
223				switch (*(mtod(m, char *) + i)) {
224				case ' ':
225					if (!inspaces) {
226						spaces++;
227						inspaces = 1;
228					}
229					break;
230				case '\r':
231				case '\n':
232					DPRINT("newline");
233					goto fallout;
234				default:
235					if (spaces == 2) {
236						/* make sure we have enough data left */
237						if (cc < sizeof("HTTP/1.0") - 1) {
238							if (mbufstrncmp(m, n, i, cc, "HTTP/1.") == 1) {
239								DPRINT("mbufstrncmp ok");
240								goto readmore;
241							} else {
242								DPRINT("mbufstrncmp bad");
243								goto fallout;
244							}
245						} else if (mbufstrcmp(m, n, i, "HTTP/1.0") == 1 ||
246									mbufstrcmp(m, n, i, "HTTP/1.1") == 1) {
247								DPRINT("mbufstrcmp ok");
248								soishttpconnected(so, arg, waitflag);
249								return;
250						} else {
251							DPRINT("mbufstrcmp bad");
252							goto fallout;
253						}
254					}
255					inspaces = 0;
256					break;
257				}
258			}
259		}
260	}
261readmore:
262	DPRINT("readmore");
263	/*
264	 * if we hit here we haven't hit something
265	 * we don't understand or a newline, so try again
266	 */
267	so->so_upcall = soparsehttpvers;
268	so->so_rcv.sb_flags |= SB_UPCALL;
269	return;
270
271fallout:
272	DPRINT("fallout");
273	so->so_upcall = NULL;
274	so->so_rcv.sb_flags &= ~SB_UPCALL;
275	soisconnected(so);
276	return;
277}
278
279
280#define NCHRS 3
281
282static void
283soishttpconnected(struct socket *so, void *arg, int waitflag)
284{
285	char a, b, c;
286	struct mbuf *m, *n;
287	int ccleft, copied;
288
289	DPRINT("start");
290	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
291		goto gotit;
292
293	/*
294	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
295	 * copied - how much we've copied so far
296	 * ccleft - how many bytes remaining in the socketbuffer
297	 * just loop over the mbufs subtracting from 'ccleft' until we only
298	 * have NCHRS left
299	 */
300	copied = 0;
301	ccleft = so->so_rcv.sb_cc;
302	if (ccleft < NCHRS)
303		goto readmore;
304	a = b = c = '\0';
305	for (m = so->so_rcv.sb_mb; m; m = n) {
306		n = m->m_nextpkt;
307		for (; m; m = m->m_next) {
308			ccleft -= m->m_len;
309			if (ccleft <= NCHRS) {
310				char *src;
311				int tocopy;
312
313				tocopy = (NCHRS - ccleft) - copied;
314				src = mtod(m, char *) + (m->m_len - tocopy);
315
316				while (tocopy--) {
317					switch (copied++) {
318					case 0:
319						a = *src++;
320						break;
321					case 1:
322						b = *src++;
323						break;
324					case 2:
325						c = *src++;
326						break;
327					}
328				}
329			}
330		}
331	}
332	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
333		/* we have all request headers */
334		goto gotit;
335	}
336
337readmore:
338	so->so_upcall = soishttpconnected;
339	so->so_rcv.sb_flags |= SB_UPCALL;
340	return;
341
342gotit:
343	so->so_upcall = NULL;
344	so->so_rcv.sb_flags &= ~SB_UPCALL;
345	soisconnected(so);
346	return;
347}
348