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accf_http.c revision 1.3 
      1 /*	$NetBSD: accf_http.c,v 1.3 2008/11/12 12:36:28 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000 Paycounter, Inc.
      5  * Author: Alfred Perlstein <alfred (at) paycounter.com>, <alfred (at) 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 1.3 2008/11/12 12:36:28 ad 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 MODULE(MODULE_CLASS_MISC, accf_http, NULL);
     47 
     48 /* check for GET/HEAD */
     49 static void sohashttpget(struct socket *so, void *arg, int waitflag);
     50 /* check for HTTP/1.0 or HTTP/1.1 */
     51 static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
     52 /* check for end of HTTP/1.x request */
     53 static void soishttpconnected(struct socket *so, void *arg, int waitflag);
     54 /* strcmp on an mbuf chain */
     55 static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp);
     56 /* strncmp on an mbuf chain */
     57 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
     58 	int len, const char *cmp);
     59 /* socketbuffer is full */
     60 static int sbfull(struct sockbuf *sb);
     61 
     62 static struct accept_filter accf_http_filter = {
     63 	.accf_name = "httpready",
     64 	.accf_callback = sohashttpget,
     65 };
     66 
     67 /*
     68  * Names of HTTP Accept filter sysctl objects
     69  */
     70 
     71 #define ACCFCTL_PARSEVER	1	/* Parse HTTP version */
     72 
     73 static int parse_http_version = 1;
     74 
     75 /* XXX pseudo-device */
     76 void	accf_httpattach(int);
     77 
     78 void
     79 accf_httpattach(int junk)
     80 {
     81 
     82 }
     83 
     84 static int
     85 accf_http_modcmd(modcmd_t cmd, void *arg)
     86 {
     87 	static struct sysctllog *clog;
     88 	int error;
     89 
     90 	switch (cmd) {
     91 	case MODULE_CMD_INIT:
     92 		error = accept_filt_add(&accf_http_filter);
     93 		if (error != 0) {
     94 			return error;
     95 		}
     96 		sysctl_createv(&clog, 0, NULL, NULL,
     97 		       CTLFLAG_PERMANENT,
     98 		       CTLTYPE_NODE, "net", NULL,
     99 		       NULL, 0, NULL, 0,
    100 		       CTL_NET, CTL_EOL);
    101 		sysctl_createv(&clog, 0, NULL, NULL,
    102 		       CTLFLAG_PERMANENT,
    103 		       CTLTYPE_NODE, "inet", NULL,
    104 		       NULL, 0, NULL, 0,
    105 		       CTL_NET, PF_INET, CTL_EOL);
    106 		sysctl_createv(&clog, 0, NULL, NULL,
    107 		       CTLFLAG_PERMANENT,
    108 		       CTLTYPE_NODE, "accf", NULL,
    109 		       NULL, 0, NULL, 0,
    110 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
    111 		sysctl_createv(&clog, 0, NULL, NULL,
    112 		       CTLFLAG_PERMANENT,
    113 		       CTLTYPE_NODE, "http",
    114 		       SYSCTL_DESCR("HTTP accept filter"),
    115 		       NULL, 0, NULL, 0,
    116 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP, CTL_EOL);
    117 		sysctl_createv(&clog, 0, NULL, NULL,
    118 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    119 		       CTLTYPE_INT, "parsehttpversion",
    120 		       SYSCTL_DESCR("Parse http version so that non "
    121 				    "1.x requests work"),
    122 		       NULL, 0, &parse_http_version, 0,
    123 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP,
    124 		       ACCFCTL_PARSEVER, CTL_EOL);
    125 		return 0;
    126 
    127 	case MODULE_CMD_FINI:
    128 		error = accept_filt_del(&accf_http_filter);
    129 		if (error != 0) {
    130 			return error;
    131 		}
    132 		sysctl_teardown(&clog);
    133 		return 0;
    134 
    135 	default:
    136 		return ENOTTY;
    137 	}
    138 }
    139 
    140 #ifdef ACCF_HTTP_DEBUG
    141 #define DPRINT(fmt, args...)						\
    142 	do {								\
    143 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
    144 	} while (0)
    145 #else
    146 #define DPRINT(fmt, args...)
    147 #endif
    148 
    149 static int
    150 sbfull(struct sockbuf *sb)
    151 {
    152 
    153 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
    154 	    "mbcnt(%ld) >= mbmax(%ld): %d",
    155 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
    156 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
    157 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
    158 }
    159 
    160 /*
    161  * start at mbuf m, (must provide npkt if exists)
    162  * starting at offset in m compare characters in mbuf chain for 'cmp'
    163  */
    164 static int
    165 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp)
    166 {
    167 	struct mbuf *n;
    168 
    169 	for (; m != NULL; m = n) {
    170 		n = npkt;
    171 		if (npkt)
    172 			npkt = npkt->m_nextpkt;
    173 		for (; m; m = m->m_next) {
    174 			for (; offset < m->m_len; offset++, cmp++) {
    175 				if (*cmp == '\0')
    176 					return (1);
    177 				else if (*cmp != *(mtod(m, char *) + offset))
    178 					return (0);
    179 			}
    180 			if (*cmp == '\0')
    181 				return (1);
    182 			offset = 0;
    183 		}
    184 	}
    185 	return (0);
    186 }
    187 
    188 /*
    189  * start at mbuf m, (must provide npkt if exists)
    190  * starting at offset in m compare characters in mbuf chain for 'cmp'
    191  * stop at 'max' characters
    192  */
    193 static int
    194 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int len, const char *cmp)
    195 {
    196 	struct mbuf *n;
    197 
    198 	for (; m != NULL; m = n) {
    199 		n = npkt;
    200 		if (npkt)
    201 			npkt = npkt->m_nextpkt;
    202 		for (; m; m = m->m_next) {
    203 			for (; offset < m->m_len; offset++, cmp++, len--) {
    204 				if (len == 0 || *cmp == '\0')
    205 					return (1);
    206 				else if (*cmp != *(mtod(m, char *) + offset))
    207 					return (0);
    208 			}
    209 			if (len == 0 || *cmp == '\0')
    210 				return (1);
    211 			offset = 0;
    212 		}
    213 	}
    214 	return (0);
    215 }
    216 
    217 #define STRSETUP(sptr, slen, str)					\
    218 	do {								\
    219 		sptr = str;						\
    220 		slen = sizeof(str) - 1;					\
    221 	} while(0)
    222 
    223 static void
    224 sohashttpget(struct socket *so, void *arg, int waitflag)
    225 {
    226 
    227 	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
    228 		struct mbuf *m;
    229 		const char *cmp;
    230 		int	cmplen, cc;
    231 
    232 		m = so->so_rcv.sb_mb;
    233 		cc = so->so_rcv.sb_cc - 1;
    234 		if (cc < 1)
    235 			return;
    236 		switch (*mtod(m, char *)) {
    237 		case 'G':
    238 			STRSETUP(cmp, cmplen, "ET ");
    239 			break;
    240 		case 'H':
    241 			STRSETUP(cmp, cmplen, "EAD ");
    242 			break;
    243 		default:
    244 			goto fallout;
    245 		}
    246 		if (cc < cmplen) {
    247 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
    248 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
    249 				return;
    250 			} else {
    251 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
    252 				goto fallout;
    253 			}
    254 		}
    255 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
    256 			DPRINT("mbufstrcmp ok");
    257 			if (parse_http_version == 0)
    258 				soishttpconnected(so, arg, waitflag);
    259 			else
    260 				soparsehttpvers(so, arg, waitflag);
    261 			return;
    262 		}
    263 		DPRINT("mbufstrcmp bad");
    264 	}
    265 
    266 fallout:
    267 	DPRINT("fallout");
    268 	so->so_upcall = NULL;
    269 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    270 	soisconnected(so);
    271 	return;
    272 }
    273 
    274 static void
    275 soparsehttpvers(struct socket *so, void *arg, int waitflag)
    276 {
    277 	struct mbuf *m, *n;
    278 	int	i, cc, spaces, inspaces;
    279 
    280 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    281 		goto fallout;
    282 
    283 	m = so->so_rcv.sb_mb;
    284 	cc = so->so_rcv.sb_cc;
    285 	inspaces = spaces = 0;
    286 	for (m = so->so_rcv.sb_mb; m; m = n) {
    287 		n = m->m_nextpkt;
    288 		for (; m; m = m->m_next) {
    289 			for (i = 0; i < m->m_len; i++, cc--) {
    290 				switch (*(mtod(m, char *) + i)) {
    291 				case ' ':
    292 					/* tabs? '\t' */
    293 					if (!inspaces) {
    294 						spaces++;
    295 						inspaces = 1;
    296 					}
    297 					break;
    298 				case '\r':
    299 				case '\n':
    300 					DPRINT("newline");
    301 					goto fallout;
    302 				default:
    303 					if (spaces != 2) {
    304 						inspaces = 0;
    305 						break;
    306 					}
    307 
    308 					/*
    309 					 * if we don't have enough characters
    310 					 * left (cc < sizeof("HTTP/1.0") - 1)
    311 					 * then see if the remaining ones
    312 					 * are a request we can parse.
    313 					 */
    314 					if (cc < sizeof("HTTP/1.0") - 1) {
    315 						if (mbufstrncmp(m, n, i, cc,
    316 							"HTTP/1.") == 1) {
    317 							DPRINT("ok");
    318 							goto readmore;
    319 						} else {
    320 							DPRINT("bad");
    321 							goto fallout;
    322 						}
    323 					} else if (
    324 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
    325 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
    326 							DPRINT("ok");
    327 							soishttpconnected(so,
    328 							    arg, waitflag);
    329 							return;
    330 					} else {
    331 						DPRINT("bad");
    332 						goto fallout;
    333 					}
    334 				}
    335 			}
    336 		}
    337 	}
    338 readmore:
    339 	DPRINT("readmore");
    340 	/*
    341 	 * if we hit here we haven't hit something
    342 	 * we don't understand or a newline, so try again
    343 	 */
    344 	so->so_upcall = soparsehttpvers;
    345 	so->so_rcv.sb_flags |= SB_UPCALL;
    346 	return;
    347 
    348 fallout:
    349 	DPRINT("fallout");
    350 	so->so_upcall = NULL;
    351 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    352 	soisconnected(so);
    353 	return;
    354 }
    355 
    356 
    357 #define NCHRS 3
    358 
    359 static void
    360 soishttpconnected(struct socket *so, void *arg, int waitflag)
    361 {
    362 	char a, b, c;
    363 	struct mbuf *m, *n;
    364 	int ccleft, copied;
    365 
    366 	DPRINT("start");
    367 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    368 		goto gotit;
    369 
    370 	/*
    371 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
    372 	 * copied - how much we've copied so far
    373 	 * ccleft - how many bytes remaining in the socketbuffer
    374 	 * just loop over the mbufs subtracting from 'ccleft' until we only
    375 	 * have NCHRS left
    376 	 */
    377 	copied = 0;
    378 	ccleft = so->so_rcv.sb_cc;
    379 	if (ccleft < NCHRS)
    380 		goto readmore;
    381 	a = b = c = '\0';
    382 	for (m = so->so_rcv.sb_mb; m; m = n) {
    383 		n = m->m_nextpkt;
    384 		for (; m; m = m->m_next) {
    385 			ccleft -= m->m_len;
    386 			if (ccleft <= NCHRS) {
    387 				char *src;
    388 				int tocopy;
    389 
    390 				tocopy = (NCHRS - ccleft) - copied;
    391 				src = mtod(m, char *) + (m->m_len - tocopy);
    392 
    393 				while (tocopy--) {
    394 					switch (copied++) {
    395 					case 0:
    396 						a = *src++;
    397 						break;
    398 					case 1:
    399 						b = *src++;
    400 						break;
    401 					case 2:
    402 						c = *src++;
    403 						break;
    404 					}
    405 				}
    406 			}
    407 		}
    408 	}
    409 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
    410 		/* we have all request headers */
    411 		goto gotit;
    412 	}
    413 
    414 readmore:
    415 	so->so_upcall = soishttpconnected;
    416 	so->so_rcv.sb_flags |= SB_UPCALL;
    417 	return;
    418 
    419 gotit:
    420 	so->so_upcall = NULL;
    421 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    422 	soisconnected(so);
    423 	return;
    424 }
    425