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 */
44 static int sohashttpget(struct socket *so, void *arg, int waitflag);
45 /* check for HTTP/1.0 or HTTP/1.1 */
46 static int soparsehttpvers(struct socket *so, void *arg, int waitflag);
47 /* check for end of HTTP/1.x request */
48 static int soishttpconnected(struct socket *so, void *arg, int waitflag);
49 /* strcmp on an mbuf chain */
50 static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
51 /* strncmp on an mbuf chain */
52 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
53 int max, char *cmp);
54 /* socketbuffer is full */
55 static int sbfull(struct sockbuf *sb);
56
57 ACCEPT_FILTER_DEFINE(accf_http, "httpready", sohashttpget, NULL, NULL, 1);
58
59 static int parse_http_version = 1;
60
61 static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
62 "HTTP accept filter");
63 SYSCTL_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
76 static int
77 sbfull(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 */
91 static int
92 mbufstrcmp(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 */
120 static int
121 mbufstrncmp(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
150 static int
151 sohashttpget(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
193 fallout:
194 DPRINT("fallout");
195 return (SU_ISCONNECTED);
196 }
197
198 static int
199 soparsehttpvers(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 }
261 readmore:
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
270 fallout:
271 DPRINT("fallout");
272 return (SU_ISCONNECTED);
273 }
274
275
276 #define NCHRS 3
277
278 static int
279 soishttpconnected(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
333 readmore:
334 soupcall_set(so, SO_RCV, soishttpconnected, arg);
335 return (SU_OK);
336
337 gotit:
338 return (SU_ISCONNECTED);
339 }
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