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, CTLFLAG_RW, 0,
62"HTTP accept filter");
63SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
64    &parse_http_version, 1,
65    "Parse http version so that non 1.x requests work");
66
67#ifdef ACCF_HTTP_DEBUG
68#define DPRINT(fmt, args...)						\
69	do {								\
70		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
71	} while (0)
72#else
73#define DPRINT(fmt, args...)
74#endif
75
76static int
77sbfull(struct sockbuf *sb)
78{
79
80	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
81	    "mbcnt(%ld) >= mbmax(%ld): %d",
82	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
83	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
84	return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
85}
86
87/*
88 * start at mbuf m, (must provide npkt if exists)
89 * starting at offset in m compare characters in mbuf chain for 'cmp'
90 */
91static int
92mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
93{
94	struct mbuf *n;
95
96	for (; m != NULL; m = n) {
97		n = npkt;
98		if (npkt)
99			npkt = npkt->m_nextpkt;
100		for (; m; m = m->m_next) {
101			for (; offset < m->m_len; offset++, cmp++) {
102				if (*cmp == '\0')
103					return (1);
104				else if (*cmp != *(mtod(m, char *) + offset))
105					return (0);
106			}
107			if (*cmp == '\0')
108				return (1);
109			offset = 0;
110		}
111	}
112	return (0);
113}
114
115/*
116 * start at mbuf m, (must provide npkt if exists)
117 * starting at offset in m compare characters in mbuf chain for 'cmp'
118 * stop at 'max' characters
119 */
120static int
121mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
122{
123	struct mbuf *n;
124
125	for (; m != NULL; m = n) {
126		n = npkt;
127		if (npkt)
128			npkt = npkt->m_nextpkt;
129		for (; m; m = m->m_next) {
130			for (; offset < m->m_len; offset++, cmp++, max--) {
131				if (max == 0 || *cmp == '\0')
132					return (1);
133				else if (*cmp != *(mtod(m, char *) + offset))
134					return (0);
135			}
136			if (max == 0 || *cmp == '\0')
137				return (1);
138			offset = 0;
139		}
140	}
141	return (0);
142}
143
144#define STRSETUP(sptr, slen, str)					\
145	do {								\
146		sptr = str;						\
147		slen = sizeof(str) - 1;					\
148	} while(0)
149
150static int
151sohashttpget(struct socket *so, void *arg, int waitflag)
152{
153
154	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 &&
155	    !sbfull(&so->so_rcv)) {
156		struct mbuf *m;
157		char *cmp;
158		int	cmplen, cc;
159
160		m = so->so_rcv.sb_mb;
161		cc = sbavail(&so->so_rcv) - 1;
162		if (cc < 1)
163			return (SU_OK);
164		switch (*mtod(m, char *)) {
165		case 'G':
166			STRSETUP(cmp, cmplen, "ET ");
167			break;
168		case 'H':
169			STRSETUP(cmp, cmplen, "EAD ");
170			break;
171		default:
172			goto fallout;
173		}
174		if (cc < cmplen) {
175			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
176				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
177				return (SU_OK);
178			} else {
179				DPRINT("short cc (%d) mbufstrncmp failed", cc);
180				goto fallout;
181			}
182		}
183		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
184			DPRINT("mbufstrcmp ok");
185			if (parse_http_version == 0)
186				return (soishttpconnected(so, arg, waitflag));
187			else
188				return (soparsehttpvers(so, arg, waitflag));
189		}
190		DPRINT("mbufstrcmp bad");
191	}
192
193fallout:
194	DPRINT("fallout");
195	return (SU_ISCONNECTED);
196}
197
198static int
199soparsehttpvers(struct socket *so, void *arg, int waitflag)
200{
201	struct mbuf *m, *n;
202	int	i, cc, spaces, inspaces;
203
204	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
205		goto fallout;
206
207	m = so->so_rcv.sb_mb;
208	cc = sbavail(&so->so_rcv);
209	inspaces = spaces = 0;
210	for (m = so->so_rcv.sb_mb; m; m = n) {
211		n = m->m_nextpkt;
212		for (; m; m = m->m_next) {
213			for (i = 0; i < m->m_len; i++, cc--) {
214				switch (*(mtod(m, char *) + i)) {
215				case ' ':
216					/* tabs? '\t' */
217					if (!inspaces) {
218						spaces++;
219						inspaces = 1;
220					}
221					break;
222				case '\r':
223				case '\n':
224					DPRINT("newline");
225					goto fallout;
226				default:
227					if (spaces != 2) {
228						inspaces = 0;
229						break;
230					}
231
232					/*
233					 * if we don't have enough characters
234					 * left (cc < sizeof("HTTP/1.0") - 1)
235					 * then see if the remaining ones
236					 * are a request we can parse.
237					 */
238					if (cc < sizeof("HTTP/1.0") - 1) {
239						if (mbufstrncmp(m, n, i, cc,
240							"HTTP/1.") == 1) {
241							DPRINT("ok");
242							goto readmore;
243						} else {
244							DPRINT("bad");
245							goto fallout;
246						}
247					} else if (
248					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
249					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
250						DPRINT("ok");
251						return (soishttpconnected(so,
252						    arg, waitflag));
253					} else {
254						DPRINT("bad");
255						goto fallout;
256					}
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	soupcall_set(so, SO_RCV, soparsehttpvers, arg);
268	return (SU_OK);
269
270fallout:
271	DPRINT("fallout");
272	return (SU_ISCONNECTED);
273}
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