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