xref: /netbsd-src/sys/netinet/accf_http.c (revision ccd9df534e375a4366c5b55f23782053c7a98d82) 
1 /*	$NetBSD: accf_http.c,v 1.10 2020/03/16 21:20:11 pgoyette Exp $	*/
2 
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 __KERNEL_RCSID(0, "$NetBSD: accf_http.c,v 1.10 2020/03/16 21:20:11 pgoyette Exp $");
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/socket.h>
42 #include <sys/socketvar.h>
43 
44 #include <netinet/accept_filter.h>
45 
46 #include "ioconf.h"
47 
48 MODULE(MODULE_CLASS_MISC, accf_httpready, NULL);
49 
50 /* check for GET/HEAD */
51 static void sohashttpget(struct socket *so, void *arg, int events, int waitflag);
52 /* check for HTTP/1.0 or HTTP/1.1 */
53 static void soparsehttpvers(struct socket *so, void *arg, int events, int waitflag);
54 /* check for end of HTTP/1.x request */
55 static void soishttpconnected(struct socket *so, void *arg, int events, int waitflag);
56 /* strcmp on an mbuf chain */
57 static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp);
58 /* strncmp on an mbuf chain */
59 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
60 	int len, const char *cmp);
61 /* socketbuffer is full */
62 static int sbfull(struct sockbuf *sb);
63 
64 static struct accept_filter accf_http_filter = {
65 	.accf_name = "httpready",
66 	.accf_callback = sohashttpget,
67 };
68 
69 /*
70  * Names of HTTP Accept filter sysctl objects
71  */
72 
73 #define ACCFCTL_PARSEVER	1	/* Parse HTTP version */
74 
75 static int parse_http_version = 1;
76 
77 void
78 accf_httpattach(int junk)
79 {
80 
81 }
82 
83 SYSCTL_SETUP(accf_sysctl_setup, "accf sysctl")
84 {
85 
86 	sysctl_createv(clog, 0, NULL, NULL,
87 	       CTLFLAG_PERMANENT,
88 	       CTLTYPE_NODE, "inet", NULL,
89 	       NULL, 0, NULL, 0,
90 	       CTL_NET, PF_INET, CTL_EOL);
91 	sysctl_createv(clog, 0, NULL, NULL,
92 	       CTLFLAG_PERMANENT,
93 	       CTLTYPE_NODE, "accf", NULL,
94 	       NULL, 0, NULL, 0,
95 	       CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
96 	sysctl_createv(clog, 0, NULL, NULL,
97 	       CTLFLAG_PERMANENT,
98 	       CTLTYPE_NODE, "http",
99 	       SYSCTL_DESCR("HTTP accept filter"),
100 	       NULL, 0, NULL, 0,
101 	       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP, CTL_EOL);
102 	sysctl_createv(clog, 0, NULL, NULL,
103 	       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
104 	       CTLTYPE_INT, "parsehttpversion",
105 	       SYSCTL_DESCR("Parse http version so that non "
106 			    "1.x requests work"),
107 	       NULL, 0, &parse_http_version, 0,
108 	       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP,
109 	       ACCFCTL_PARSEVER, CTL_EOL);
110 }
111 
112 static int
113 accf_httpready_modcmd(modcmd_t cmd, void *arg)
114 {
115 	int error;
116 
117 	switch (cmd) {
118 	case MODULE_CMD_INIT:
119 		error = accept_filt_add(&accf_http_filter);
120 		return 0;
121 
122 	case MODULE_CMD_FINI:
123 		error = accept_filt_del(&accf_http_filter);
124 		return error;
125 
126 	default:
127 		return ENOTTY;
128 	}
129 }
130 
131 #ifdef ACCF_HTTP_DEBUG
132 #define DPRINT(fmt, args...)						\
133 	do {								\
134 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
135 	} while (0)
136 #else
137 #define DPRINT(fmt, args...)
138 #endif
139 
140 static int
141 sbfull(struct sockbuf *sb)
142 {
143 
144 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
145 	    "mbcnt(%ld) >= mbmax(%ld): %d",
146 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
147 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
148 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
149 }
150 
151 /*
152  * start at mbuf m, (must provide npkt if exists)
153  * starting at offset in m compare characters in mbuf chain for 'cmp'
154  */
155 static int
156 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp)
157 {
158 	struct mbuf *n;
159 
160 	for (; m != NULL; m = n) {
161 		n = npkt;
162 		if (npkt)
163 			npkt = npkt->m_nextpkt;
164 		for (; m; m = m->m_next) {
165 			for (; offset < m->m_len; offset++, cmp++) {
166 				if (*cmp == '\0')
167 					return (1);
168 				else if (*cmp != *(mtod(m, char *) + offset))
169 					return (0);
170 			}
171 			if (*cmp == '\0')
172 				return (1);
173 			offset = 0;
174 		}
175 	}
176 	return (0);
177 }
178 
179 /*
180  * start at mbuf m, (must provide npkt if exists)
181  * starting at offset in m compare characters in mbuf chain for 'cmp'
182  * stop at 'max' characters
183  */
184 static int
185 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int len, const char *cmp)
186 {
187 	struct mbuf *n;
188 
189 	for (; m != NULL; m = n) {
190 		n = npkt;
191 		if (npkt)
192 			npkt = npkt->m_nextpkt;
193 		for (; m; m = m->m_next) {
194 			for (; offset < m->m_len; offset++, cmp++, len--) {
195 				if (len == 0 || *cmp == '\0')
196 					return (1);
197 				else if (*cmp != *(mtod(m, char *) + offset))
198 					return (0);
199 			}
200 			if (len == 0 || *cmp == '\0')
201 				return (1);
202 			offset = 0;
203 		}
204 	}
205 	return (0);
206 }
207 
208 #define STRSETUP(sptr, slen, str)					\
209 	do {								\
210 		sptr = str;						\
211 		slen = sizeof(str) - 1;					\
212 	} while(0)
213 
214 static void
215 sohashttpget(struct socket *so, void *arg, int events, int waitflag)
216 {
217 
218 	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
219 		struct mbuf *m;
220 		const char *cmp;
221 		int	cmplen, cc;
222 
223 		m = so->so_rcv.sb_mb;
224 		cc = so->so_rcv.sb_cc - 1;
225 		if (cc < 1)
226 			return;
227 		switch (*mtod(m, char *)) {
228 		case 'G':
229 			STRSETUP(cmp, cmplen, "ET ");
230 			break;
231 		case 'H':
232 			STRSETUP(cmp, cmplen, "EAD ");
233 			break;
234 		default:
235 			goto fallout;
236 		}
237 		if (cc < cmplen) {
238 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
239 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
240 				return;
241 			} else {
242 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
243 				goto fallout;
244 			}
245 		}
246 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
247 			DPRINT("mbufstrcmp ok");
248 			if (parse_http_version == 0)
249 				soishttpconnected(so, arg, events, waitflag);
250 			else
251 				soparsehttpvers(so, arg, events, waitflag);
252 			return;
253 		}
254 		DPRINT("mbufstrcmp bad");
255 	}
256 
257 fallout:
258 	DPRINT("fallout");
259 	so->so_upcall = NULL;
260 	so->so_rcv.sb_flags &= ~SB_UPCALL;
261 	soisconnected(so);
262 	return;
263 }
264 
265 static void
266 soparsehttpvers(struct socket *so, void *arg, int events, int waitflag)
267 {
268 	struct mbuf *m, *n;
269 	int	i, cc, spaces, inspaces;
270 
271 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
272 		goto fallout;
273 
274 	m = so->so_rcv.sb_mb;
275 	cc = so->so_rcv.sb_cc;
276 	inspaces = spaces = 0;
277 	for (m = so->so_rcv.sb_mb; m; m = n) {
278 		n = m->m_nextpkt;
279 		for (; m; m = m->m_next) {
280 			for (i = 0; i < m->m_len; i++, cc--) {
281 				switch (*(mtod(m, char *) + i)) {
282 				case ' ':
283 					/* tabs? '\t' */
284 					if (!inspaces) {
285 						spaces++;
286 						inspaces = 1;
287 					}
288 					break;
289 				case '\r':
290 				case '\n':
291 					DPRINT("newline");
292 					goto fallout;
293 				default:
294 					if (spaces != 2) {
295 						inspaces = 0;
296 						break;
297 					}
298 
299 					/*
300 					 * if we don't have enough characters
301 					 * left (cc < sizeof("HTTP/1.0") - 1)
302 					 * then see if the remaining ones
303 					 * are a request we can parse.
304 					 */
305 					if (cc < sizeof("HTTP/1.0") - 1) {
306 						if (mbufstrncmp(m, n, i, cc,
307 							"HTTP/1.") == 1) {
308 							DPRINT("ok");
309 							goto readmore;
310 						} else {
311 							DPRINT("bad");
312 							goto fallout;
313 						}
314 					} else if (
315 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
316 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
317 						DPRINT("ok");
318 						soishttpconnected(so,
319 						    arg, events, waitflag);
320 						return;
321 					} else {
322 						DPRINT("bad");
323 						goto fallout;
324 					}
325 				}
326 			}
327 		}
328 	}
329 readmore:
330 	DPRINT("readmore");
331 	/*
332 	 * if we hit here we haven't hit something
333 	 * we don't understand or a newline, so try again
334 	 */
335 	so->so_upcall = soparsehttpvers;
336 	so->so_rcv.sb_flags |= SB_UPCALL;
337 	return;
338 
339 fallout:
340 	DPRINT("fallout");
341 	so->so_upcall = NULL;
342 	so->so_rcv.sb_flags &= ~SB_UPCALL;
343 	soisconnected(so);
344 	return;
345 }
346 
347 
348 #define NCHRS 3
349 
350 static void
351 soishttpconnected(struct socket *so, void *arg, int events, int waitflag)
352 {
353 	char a, b, c;
354 	struct mbuf *m, *n;
355 	int ccleft, copied;
356 
357 	DPRINT("start");
358 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
359 		goto gotit;
360 
361 	/*
362 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
363 	 * copied - how much we've copied so far
364 	 * ccleft - how many bytes remaining in the socketbuffer
365 	 * just loop over the mbufs subtracting from 'ccleft' until we only
366 	 * have NCHRS left
367 	 */
368 	copied = 0;
369 	ccleft = so->so_rcv.sb_cc;
370 	if (ccleft < NCHRS)
371 		goto readmore;
372 	a = b = c = '\0';
373 	for (m = so->so_rcv.sb_mb; m; m = n) {
374 		n = m->m_nextpkt;
375 		for (; m; m = m->m_next) {
376 			ccleft -= m->m_len;
377 			if (ccleft <= NCHRS) {
378 				char *src;
379 				int tocopy;
380 
381 				tocopy = (NCHRS - ccleft) - copied;
382 				src = mtod(m, char *) + (m->m_len - tocopy);
383 
384 				while (tocopy--) {
385 					switch (copied++) {
386 					case 0:
387 						a = *src++;
388 						break;
389 					case 1:
390 						b = *src++;
391 						break;
392 					case 2:
393 						c = *src++;
394 						break;
395 					}
396 				}
397 			}
398 		}
399 	}
400 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
401 		/* we have all request headers */
402 		goto gotit;
403 	}
404 
405 readmore:
406 	so->so_upcall = soishttpconnected;
407 	so->so_rcv.sb_flags |= SB_UPCALL;
408 	return;
409 
410 gotit:
411 	so->so_upcall = NULL;
412 	so->so_rcv.sb_flags &= ~SB_UPCALL;
413 	soisconnected(so);
414 	return;
415 }
416