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