1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
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#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 int sohashttpget(struct socket *so, void *arg, int waitflag);
43/* check for HTTP/1.0 or HTTP/1.1 */
44static int soparsehttpvers(struct socket *so, void *arg, int waitflag);
45/* check for end of HTTP/1.x request */
46static int 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
55ACCEPT_FILTER_DEFINE(accf_http, "httpready", sohashttpget, NULL, NULL, 1);
56
57static int parse_http_version = 1;
58
59static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http,
60    CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
61    "HTTP accept filter");
62SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
63    &parse_http_version, 1,
64    "Parse http version so that non 1.x requests work");
65
66#ifdef ACCF_HTTP_DEBUG
67#define DPRINT(fmt, args...)						\
68	do {								\
69		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
70	} while (0)
71#else
72#define DPRINT(fmt, args...)
73#endif
74
75static int
76sbfull(struct sockbuf *sb)
77{
78
79	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
80	    "mbcnt(%ld) >= mbmax(%ld): %d",
81	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
82	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
83	return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
84}
85
86/*
87 * start at mbuf m, (must provide npkt if exists)
88 * starting at offset in m compare characters in mbuf chain for 'cmp'
89 */
90static int
91mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
92{
93	struct mbuf *n;
94
95	for (; m != NULL; m = n) {
96		n = npkt;
97		if (npkt)
98			npkt = npkt->m_nextpkt;
99		for (; m; m = m->m_next) {
100			for (; offset < m->m_len; offset++, cmp++) {
101				if (*cmp == '\0')
102					return (1);
103				else if (*cmp != *(mtod(m, char *) + offset))
104					return (0);
105			}
106			if (*cmp == '\0')
107				return (1);
108			offset = 0;
109		}
110	}
111	return (0);
112}
113
114/*
115 * start at mbuf m, (must provide npkt if exists)
116 * starting at offset in m compare characters in mbuf chain for 'cmp'
117 * stop at 'max' characters
118 */
119static int
120mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
121{
122	struct mbuf *n;
123
124	for (; m != NULL; m = n) {
125		n = npkt;
126		if (npkt)
127			npkt = npkt->m_nextpkt;
128		for (; m; m = m->m_next) {
129			for (; offset < m->m_len; offset++, cmp++, max--) {
130				if (max == 0 || *cmp == '\0')
131					return (1);
132				else if (*cmp != *(mtod(m, char *) + offset))
133					return (0);
134			}
135			if (max == 0 || *cmp == '\0')
136				return (1);
137			offset = 0;
138		}
139	}
140	return (0);
141}
142
143#define STRSETUP(sptr, slen, str)					\
144	do {								\
145		sptr = str;						\
146		slen = sizeof(str) - 1;					\
147	} while(0)
148
149static int
150sohashttpget(struct socket *so, void *arg, int waitflag)
151{
152
153	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 &&
154	    !sbfull(&so->so_rcv)) {
155		struct mbuf *m;
156		char *cmp;
157		int	cmplen, cc;
158
159		m = so->so_rcv.sb_mb;
160		cc = sbavail(&so->so_rcv) - 1;
161		if (cc < 1)
162			return (SU_OK);
163		switch (*mtod(m, char *)) {
164		case 'G':
165			STRSETUP(cmp, cmplen, "ET ");
166			break;
167		case 'H':
168			STRSETUP(cmp, cmplen, "EAD ");
169			break;
170		default:
171			goto fallout;
172		}
173		if (cc < cmplen) {
174			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
175				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
176				return (SU_OK);
177			} else {
178				DPRINT("short cc (%d) mbufstrncmp failed", cc);
179				goto fallout;
180			}
181		}
182		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
183			DPRINT("mbufstrcmp ok");
184			if (parse_http_version == 0)
185				return (soishttpconnected(so, arg, waitflag));
186			else
187				return (soparsehttpvers(so, arg, waitflag));
188		}
189		DPRINT("mbufstrcmp bad");
190	}
191
192fallout:
193	DPRINT("fallout");
194	return (SU_ISCONNECTED);
195}
196
197static int
198soparsehttpvers(struct socket *so, void *arg, int waitflag)
199{
200	struct mbuf *m, *n;
201	int	i, cc, spaces, inspaces;
202
203	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
204		goto fallout;
205
206	m = so->so_rcv.sb_mb;
207	cc = sbavail(&so->so_rcv);
208	inspaces = spaces = 0;
209	for (m = so->so_rcv.sb_mb; m; m = n) {
210		n = m->m_nextpkt;
211		for (; m; m = m->m_next) {
212			for (i = 0; i < m->m_len; i++, cc--) {
213				switch (*(mtod(m, char *) + i)) {
214				case ' ':
215					/* tabs? '\t' */
216					if (!inspaces) {
217						spaces++;
218						inspaces = 1;
219					}
220					break;
221				case '\r':
222				case '\n':
223					DPRINT("newline");
224					goto fallout;
225				default:
226					if (spaces != 2) {
227						inspaces = 0;
228						break;
229					}
230
231					/*
232					 * if we don't have enough characters
233					 * left (cc < sizeof("HTTP/1.0") - 1)
234					 * then see if the remaining ones
235					 * are a request we can parse.
236					 */
237					if (cc < sizeof("HTTP/1.0") - 1) {
238						if (mbufstrncmp(m, n, i, cc,
239							"HTTP/1.") == 1) {
240							DPRINT("ok");
241							goto readmore;
242						} else {
243							DPRINT("bad");
244							goto fallout;
245						}
246					} else if (
247					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
248					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
249						DPRINT("ok");
250						return (soishttpconnected(so,
251						    arg, waitflag));
252					} else {
253						DPRINT("bad");
254						goto fallout;
255					}
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	soupcall_set(so, SO_RCV, soparsehttpvers, arg);
267	return (SU_OK);
268
269fallout:
270	DPRINT("fallout");
271	return (SU_ISCONNECTED);
272}
273
274#define NCHRS 3
275
276static int
277soishttpconnected(struct socket *so, void *arg, int waitflag)
278{
279	char a, b, c;
280	struct mbuf *m, *n;
281	int ccleft, copied;
282
283	DPRINT("start");
284	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
285		goto gotit;
286
287	/*
288	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
289	 * copied - how much we've copied so far
290	 * ccleft - how many bytes remaining in the socketbuffer
291	 * just loop over the mbufs subtracting from 'ccleft' until we only
292	 * have NCHRS left
293	 */
294	copied = 0;
295	ccleft = sbavail(&so->so_rcv);
296	if (ccleft < NCHRS)
297		goto readmore;
298	a = b = c = '\0';
299	for (m = so->so_rcv.sb_mb; m; m = n) {
300		n = m->m_nextpkt;
301		for (; m; m = m->m_next) {
302			ccleft -= m->m_len;
303			if (ccleft <= NCHRS) {
304				char *src;
305				int tocopy;
306
307				tocopy = (NCHRS - ccleft) - copied;
308				src = mtod(m, char *) + (m->m_len - tocopy);
309
310				while (tocopy--) {
311					switch (copied++) {
312					case 0:
313						a = *src++;
314						break;
315					case 1:
316						b = *src++;
317						break;
318					case 2:
319						c = *src++;
320						break;
321					}
322				}
323			}
324		}
325	}
326	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
327		/* we have all request headers */
328		goto gotit;
329	}
330
331readmore:
332	soupcall_set(so, SO_RCV, soishttpconnected, arg);
333	return (SU_OK);
334
335gotit:
336	return (SU_ISCONNECTED);
337}
338