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: releng/12.0/sys/netinet/accf_http.c 326272 2017-11-27 15:23:17Z pfg $");
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 static struct accept_filter accf_http_filter = {
58 "httpready",
59 sohashttpget,
60 NULL,
61 NULL
62 };
63
64 static moduledata_t accf_http_mod = {
65 "accf_http",
66 accept_filt_generic_mod_event,
67 &accf_http_filter
68 };
69
70 DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
71
72 static int parse_http_version = 1;
73
74 static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
75 "HTTP accept filter");
76 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
77 &parse_http_version, 1,
78 "Parse http version so that non 1.x requests work");
79
80 #ifdef ACCF_HTTP_DEBUG
81 #define DPRINT(fmt, args...) \
82 do { \
83 printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args); \
84 } while (0)
85 #else
86 #define DPRINT(fmt, args...)
87 #endif
88
89 static int
90 sbfull(struct sockbuf *sb)
91 {
92
93 DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
94 "mbcnt(%ld) >= mbmax(%ld): %d",
95 sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
96 sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
97 return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
98 }
99
100 /*
101 * start at mbuf m, (must provide npkt if exists)
102 * starting at offset in m compare characters in mbuf chain for 'cmp'
103 */
104 static int
105 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
106 {
107 struct mbuf *n;
108
109 for (; m != NULL; m = n) {
110 n = npkt;
111 if (npkt)
112 npkt = npkt->m_nextpkt;
113 for (; m; m = m->m_next) {
114 for (; offset < m->m_len; offset++, cmp++) {
115 if (*cmp == '\0')
116 return (1);
117 else if (*cmp != *(mtod(m, char *) + offset))
118 return (0);
119 }
120 if (*cmp == '\0')
121 return (1);
122 offset = 0;
123 }
124 }
125 return (0);
126 }
127
128 /*
129 * start at mbuf m, (must provide npkt if exists)
130 * starting at offset in m compare characters in mbuf chain for 'cmp'
131 * stop at 'max' characters
132 */
133 static int
134 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
135 {
136 struct mbuf *n;
137
138 for (; m != NULL; m = n) {
139 n = npkt;
140 if (npkt)
141 npkt = npkt->m_nextpkt;
142 for (; m; m = m->m_next) {
143 for (; offset < m->m_len; offset++, cmp++, max--) {
144 if (max == 0 || *cmp == '\0')
145 return (1);
146 else if (*cmp != *(mtod(m, char *) + offset))
147 return (0);
148 }
149 if (max == 0 || *cmp == '\0')
150 return (1);
151 offset = 0;
152 }
153 }
154 return (0);
155 }
156
157 #define STRSETUP(sptr, slen, str) \
158 do { \
159 sptr = str; \
160 slen = sizeof(str) - 1; \
161 } while(0)
162
163 static int
164 sohashttpget(struct socket *so, void *arg, int waitflag)
165 {
166
167 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 &&
168 !sbfull(&so->so_rcv)) {
169 struct mbuf *m;
170 char *cmp;
171 int cmplen, cc;
172
173 m = so->so_rcv.sb_mb;
174 cc = sbavail(&so->so_rcv) - 1;
175 if (cc < 1)
176 return (SU_OK);
177 switch (*mtod(m, char *)) {
178 case 'G':
179 STRSETUP(cmp, cmplen, "ET ");
180 break;
181 case 'H':
182 STRSETUP(cmp, cmplen, "EAD ");
183 break;
184 default:
185 goto fallout;
186 }
187 if (cc < cmplen) {
188 if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
189 DPRINT("short cc (%d) but mbufstrncmp ok", cc);
190 return (SU_OK);
191 } else {
192 DPRINT("short cc (%d) mbufstrncmp failed", cc);
193 goto fallout;
194 }
195 }
196 if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
197 DPRINT("mbufstrcmp ok");
198 if (parse_http_version == 0)
199 return (soishttpconnected(so, arg, waitflag));
200 else
201 return (soparsehttpvers(so, arg, waitflag));
202 }
203 DPRINT("mbufstrcmp bad");
204 }
205
206 fallout:
207 DPRINT("fallout");
208 return (SU_ISCONNECTED);
209 }
210
211 static int
212 soparsehttpvers(struct socket *so, void *arg, int waitflag)
213 {
214 struct mbuf *m, *n;
215 int i, cc, spaces, inspaces;
216
217 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
218 goto fallout;
219
220 m = so->so_rcv.sb_mb;
221 cc = sbavail(&so->so_rcv);
222 inspaces = spaces = 0;
223 for (m = so->so_rcv.sb_mb; m; m = n) {
224 n = m->m_nextpkt;
225 for (; m; m = m->m_next) {
226 for (i = 0; i < m->m_len; i++, cc--) {
227 switch (*(mtod(m, char *) + i)) {
228 case ' ':
229 /* tabs? '\t' */
230 if (!inspaces) {
231 spaces++;
232 inspaces = 1;
233 }
234 break;
235 case '\r':
236 case '\n':
237 DPRINT("newline");
238 goto fallout;
239 default:
240 if (spaces != 2) {
241 inspaces = 0;
242 break;
243 }
244
245 /*
246 * if we don't have enough characters
247 * left (cc < sizeof("HTTP/1.0") - 1)
248 * then see if the remaining ones
249 * are a request we can parse.
250 */
251 if (cc < sizeof("HTTP/1.0") - 1) {
252 if (mbufstrncmp(m, n, i, cc,
253 "HTTP/1.") == 1) {
254 DPRINT("ok");
255 goto readmore;
256 } else {
257 DPRINT("bad");
258 goto fallout;
259 }
260 } else if (
261 mbufstrcmp(m, n, i, "HTTP/1.0") ||
262 mbufstrcmp(m, n, i, "HTTP/1.1")) {
263 DPRINT("ok");
264 return (soishttpconnected(so,
265 arg, waitflag));
266 } else {
267 DPRINT("bad");
268 goto fallout;
269 }
270 }
271 }
272 }
273 }
274 readmore:
275 DPRINT("readmore");
276 /*
277 * if we hit here we haven't hit something
278 * we don't understand or a newline, so try again
279 */
280 soupcall_set(so, SO_RCV, soparsehttpvers, arg);
281 return (SU_OK);
282
283 fallout:
284 DPRINT("fallout");
285 return (SU_ISCONNECTED);
286 }
287
288
289 #define NCHRS 3
290
291 static int
292 soishttpconnected(struct socket *so, void *arg, int waitflag)
293 {
294 char a, b, c;
295 struct mbuf *m, *n;
296 int ccleft, copied;
297
298 DPRINT("start");
299 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
300 goto gotit;
301
302 /*
303 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
304 * copied - how much we've copied so far
305 * ccleft - how many bytes remaining in the socketbuffer
306 * just loop over the mbufs subtracting from 'ccleft' until we only
307 * have NCHRS left
308 */
309 copied = 0;
310 ccleft = sbavail(&so->so_rcv);
311 if (ccleft < NCHRS)
312 goto readmore;
313 a = b = c = '\0';
314 for (m = so->so_rcv.sb_mb; m; m = n) {
315 n = m->m_nextpkt;
316 for (; m; m = m->m_next) {
317 ccleft -= m->m_len;
318 if (ccleft <= NCHRS) {
319 char *src;
320 int tocopy;
321
322 tocopy = (NCHRS - ccleft) - copied;
323 src = mtod(m, char *) + (m->m_len - tocopy);
324
325 while (tocopy--) {
326 switch (copied++) {
327 case 0:
328 a = *src++;
329 break;
330 case 1:
331 b = *src++;
332 break;
333 case 2:
334 c = *src++;
335 break;
336 }
337 }
338 }
339 }
340 }
341 if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
342 /* we have all request headers */
343 goto gotit;
344 }
345
346 readmore:
347 soupcall_set(so, SO_RCV, soishttpconnected, arg);
348 return (SU_OK);
349
350 gotit:
351 return (SU_ISCONNECTED);
352 }
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