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,
62 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
63 "HTTP accept filter");
64 SYSCTL_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
77 static int
78 sbfull(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 */
92 static int
93 mbufstrcmp(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 */
121 static int
122 mbufstrncmp(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
151 static int
152 sohashttpget(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
194 fallout:
195 DPRINT("fallout");
196 return (SU_ISCONNECTED);
197 }
198
199 static int
200 soparsehttpvers(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 }
262 readmore:
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
271 fallout:
272 DPRINT("fallout");
273 return (SU_ISCONNECTED);
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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