xref: /freebsd/sys/netinet/accf_http.c (revision 2be1a816b9ff69588e55be0a84cbe2a31efc0f2f)
1 /*-
2  * Copyright (c) 2000 Paycounter, Inc.
3  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
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 void sohashttpget(struct socket *so, void *arg, int waitflag);
43 /* check for HTTP/1.0 or HTTP/1.1 */
44 static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
45 /* check for end of HTTP/1.x request */
46 static void 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 static struct accept_filter accf_http_filter = {
56 	"httpready",
57 	sohashttpget,
58 	NULL,
59 	NULL
60 };
61 
62 static moduledata_t accf_http_mod = {
63 	"accf_http",
64 	accept_filt_generic_mod_event,
65 	&accf_http_filter
66 };
67 
68 DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
69 
70 static int parse_http_version = 1;
71 
72 SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
73 "HTTP accept filter");
74 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
75 &parse_http_version, 1,
76 "Parse http version so that non 1.x requests work");
77 
78 #ifdef ACCF_HTTP_DEBUG
79 #define DPRINT(fmt, args...)						\
80 	do {								\
81 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
82 	} while (0)
83 #else
84 #define DPRINT(fmt, args...)
85 #endif
86 
87 static int
88 sbfull(struct sockbuf *sb)
89 {
90 
91 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
92 	    "mbcnt(%ld) >= mbmax(%ld): %d",
93 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
94 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
95 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
96 }
97 
98 /*
99  * start at mbuf m, (must provide npkt if exists)
100  * starting at offset in m compare characters in mbuf chain for 'cmp'
101  */
102 static int
103 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
104 {
105 	struct mbuf *n;
106 
107 	for (; m != NULL; m = n) {
108 		n = npkt;
109 		if (npkt)
110 			npkt = npkt->m_nextpkt;
111 		for (; m; m = m->m_next) {
112 			for (; offset < m->m_len; offset++, cmp++) {
113 				if (*cmp == '\0')
114 					return (1);
115 				else if (*cmp != *(mtod(m, char *) + offset))
116 					return (0);
117 			}
118 			if (*cmp == '\0')
119 				return (1);
120 			offset = 0;
121 		}
122 	}
123 	return (0);
124 }
125 
126 /*
127  * start at mbuf m, (must provide npkt if exists)
128  * starting at offset in m compare characters in mbuf chain for 'cmp'
129  * stop at 'max' characters
130  */
131 static int
132 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
133 {
134 	struct mbuf *n;
135 
136 	for (; m != NULL; m = n) {
137 		n = npkt;
138 		if (npkt)
139 			npkt = npkt->m_nextpkt;
140 		for (; m; m = m->m_next) {
141 			for (; offset < m->m_len; offset++, cmp++, max--) {
142 				if (max == 0 || *cmp == '\0')
143 					return (1);
144 				else if (*cmp != *(mtod(m, char *) + offset))
145 					return (0);
146 			}
147 			if (max == 0 || *cmp == '\0')
148 				return (1);
149 			offset = 0;
150 		}
151 	}
152 	return (0);
153 }
154 
155 #define STRSETUP(sptr, slen, str)					\
156 	do {								\
157 		sptr = str;						\
158 		slen = sizeof(str) - 1;					\
159 	} while(0)
160 
161 static void
162 sohashttpget(struct socket *so, void *arg, int waitflag)
163 {
164 
165 	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
166 		struct mbuf *m;
167 		char *cmp;
168 		int	cmplen, cc;
169 
170 		m = so->so_rcv.sb_mb;
171 		cc = so->so_rcv.sb_cc - 1;
172 		if (cc < 1)
173 			return;
174 		switch (*mtod(m, char *)) {
175 		case 'G':
176 			STRSETUP(cmp, cmplen, "ET ");
177 			break;
178 		case 'H':
179 			STRSETUP(cmp, cmplen, "EAD ");
180 			break;
181 		default:
182 			goto fallout;
183 		}
184 		if (cc < cmplen) {
185 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
186 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
187 				return;
188 			} else {
189 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
190 				goto fallout;
191 			}
192 		}
193 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
194 			DPRINT("mbufstrcmp ok");
195 			if (parse_http_version == 0)
196 				soishttpconnected(so, arg, waitflag);
197 			else
198 				soparsehttpvers(so, arg, waitflag);
199 			return;
200 		}
201 		DPRINT("mbufstrcmp bad");
202 	}
203 
204 fallout:
205 	DPRINT("fallout");
206 	so->so_upcall = NULL;
207 	so->so_rcv.sb_flags &= ~SB_UPCALL;
208 	soisconnected(so);
209 	return;
210 }
211 
212 static void
213 soparsehttpvers(struct socket *so, void *arg, int waitflag)
214 {
215 	struct mbuf *m, *n;
216 	int	i, cc, spaces, inspaces;
217 
218 	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
219 		goto fallout;
220 
221 	m = so->so_rcv.sb_mb;
222 	cc = so->so_rcv.sb_cc;
223 	inspaces = spaces = 0;
224 	for (m = so->so_rcv.sb_mb; m; m = n) {
225 		n = m->m_nextpkt;
226 		for (; m; m = m->m_next) {
227 			for (i = 0; i < m->m_len; i++, cc--) {
228 				switch (*(mtod(m, char *) + i)) {
229 				case ' ':
230 					/* tabs? '\t' */
231 					if (!inspaces) {
232 						spaces++;
233 						inspaces = 1;
234 					}
235 					break;
236 				case '\r':
237 				case '\n':
238 					DPRINT("newline");
239 					goto fallout;
240 				default:
241 					if (spaces != 2) {
242 						inspaces = 0;
243 						break;
244 					}
245 
246 					/*
247 					 * if we don't have enough characters
248 					 * left (cc < sizeof("HTTP/1.0") - 1)
249 					 * then see if the remaining ones
250 					 * are a request we can parse.
251 					 */
252 					if (cc < sizeof("HTTP/1.0") - 1) {
253 						if (mbufstrncmp(m, n, i, cc,
254 							"HTTP/1.") == 1) {
255 							DPRINT("ok");
256 							goto readmore;
257 						} else {
258 							DPRINT("bad");
259 							goto fallout;
260 						}
261 					} else if (
262 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
263 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
264 							DPRINT("ok");
265 							soishttpconnected(so,
266 							    arg, waitflag);
267 							return;
268 					} else {
269 						DPRINT("bad");
270 						goto fallout;
271 					}
272 				}
273 			}
274 		}
275 	}
276 readmore:
277 	DPRINT("readmore");
278 	/*
279 	 * if we hit here we haven't hit something
280 	 * we don't understand or a newline, so try again
281 	 */
282 	so->so_upcall = soparsehttpvers;
283 	so->so_rcv.sb_flags |= SB_UPCALL;
284 	return;
285 
286 fallout:
287 	DPRINT("fallout");
288 	so->so_upcall = NULL;
289 	so->so_rcv.sb_flags &= ~SB_UPCALL;
290 	soisconnected(so);
291 	return;
292 }
293 
294 
295 #define NCHRS 3
296 
297 static void
298 soishttpconnected(struct socket *so, void *arg, int waitflag)
299 {
300 	char a, b, c;
301 	struct mbuf *m, *n;
302 	int ccleft, copied;
303 
304 	DPRINT("start");
305 	if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
306 		goto gotit;
307 
308 	/*
309 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
310 	 * copied - how much we've copied so far
311 	 * ccleft - how many bytes remaining in the socketbuffer
312 	 * just loop over the mbufs subtracting from 'ccleft' until we only
313 	 * have NCHRS left
314 	 */
315 	copied = 0;
316 	ccleft = so->so_rcv.sb_cc;
317 	if (ccleft < NCHRS)
318 		goto readmore;
319 	a = b = c = '\0';
320 	for (m = so->so_rcv.sb_mb; m; m = n) {
321 		n = m->m_nextpkt;
322 		for (; m; m = m->m_next) {
323 			ccleft -= m->m_len;
324 			if (ccleft <= NCHRS) {
325 				char *src;
326 				int tocopy;
327 
328 				tocopy = (NCHRS - ccleft) - copied;
329 				src = mtod(m, char *) + (m->m_len - tocopy);
330 
331 				while (tocopy--) {
332 					switch (copied++) {
333 					case 0:
334 						a = *src++;
335 						break;
336 					case 1:
337 						b = *src++;
338 						break;
339 					case 2:
340 						c = *src++;
341 						break;
342 					}
343 				}
344 			}
345 		}
346 	}
347 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
348 		/* we have all request headers */
349 		goto gotit;
350 	}
351 
352 readmore:
353 	so->so_upcall = soishttpconnected;
354 	so->so_rcv.sb_flags |= SB_UPCALL;
355 	return;
356 
357 gotit:
358 	so->so_upcall = NULL;
359 	so->so_rcv.sb_flags &= ~SB_UPCALL;
360 	soisconnected(so);
361 	return;
362 }
363