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accf_http.c revision 1.7.22.1 
      1 /*	$NetBSD: accf_http.c,v 1.7.22.1 2014/08/20 00:04:35 tls 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 1.7.22.1 2014/08/20 00:04:35 tls 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_httpready, NULL);
     47 
     48 /* check for GET/HEAD */
     49 static void sohashttpget(struct socket *so, void *arg, int events, int waitflag);
     50 /* check for HTTP/1.0 or HTTP/1.1 */
     51 static void soparsehttpvers(struct socket *so, void *arg, int events, int waitflag);
     52 /* check for end of HTTP/1.x request */
     53 static void soishttpconnected(struct socket *so, void *arg, int events, 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_httpready_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, "inet", NULL,
     99 		       NULL, 0, NULL, 0,
    100 		       CTL_NET, PF_INET, CTL_EOL);
    101 		sysctl_createv(&clog, 0, NULL, NULL,
    102 		       CTLFLAG_PERMANENT,
    103 		       CTLTYPE_NODE, "accf", NULL,
    104 		       NULL, 0, NULL, 0,
    105 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
    106 		sysctl_createv(&clog, 0, NULL, NULL,
    107 		       CTLFLAG_PERMANENT,
    108 		       CTLTYPE_NODE, "http",
    109 		       SYSCTL_DESCR("HTTP accept filter"),
    110 		       NULL, 0, NULL, 0,
    111 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP, CTL_EOL);
    112 		sysctl_createv(&clog, 0, NULL, NULL,
    113 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    114 		       CTLTYPE_INT, "parsehttpversion",
    115 		       SYSCTL_DESCR("Parse http version so that non "
    116 				    "1.x requests work"),
    117 		       NULL, 0, &parse_http_version, 0,
    118 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP,
    119 		       ACCFCTL_PARSEVER, CTL_EOL);
    120 		return 0;
    121 
    122 	case MODULE_CMD_FINI:
    123 		error = accept_filt_del(&accf_http_filter);
    124 		if (error != 0) {
    125 			return error;
    126 		}
    127 		sysctl_teardown(&clog);
    128 		return 0;
    129 
    130 	default:
    131 		return ENOTTY;
    132 	}
    133 }
    134 
    135 #ifdef ACCF_HTTP_DEBUG
    136 #define DPRINT(fmt, args...)						\
    137 	do {								\
    138 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
    139 	} while (0)
    140 #else
    141 #define DPRINT(fmt, args...)
    142 #endif
    143 
    144 static int
    145 sbfull(struct sockbuf *sb)
    146 {
    147 
    148 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
    149 	    "mbcnt(%ld) >= mbmax(%ld): %d",
    150 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
    151 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
    152 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
    153 }
    154 
    155 /*
    156  * start at mbuf m, (must provide npkt if exists)
    157  * starting at offset in m compare characters in mbuf chain for 'cmp'
    158  */
    159 static int
    160 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp)
    161 {
    162 	struct mbuf *n;
    163 
    164 	for (; m != NULL; m = n) {
    165 		n = npkt;
    166 		if (npkt)
    167 			npkt = npkt->m_nextpkt;
    168 		for (; m; m = m->m_next) {
    169 			for (; offset < m->m_len; offset++, cmp++) {
    170 				if (*cmp == '\0')
    171 					return (1);
    172 				else if (*cmp != *(mtod(m, char *) + offset))
    173 					return (0);
    174 			}
    175 			if (*cmp == '\0')
    176 				return (1);
    177 			offset = 0;
    178 		}
    179 	}
    180 	return (0);
    181 }
    182 
    183 /*
    184  * start at mbuf m, (must provide npkt if exists)
    185  * starting at offset in m compare characters in mbuf chain for 'cmp'
    186  * stop at 'max' characters
    187  */
    188 static int
    189 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int len, const char *cmp)
    190 {
    191 	struct mbuf *n;
    192 
    193 	for (; m != NULL; m = n) {
    194 		n = npkt;
    195 		if (npkt)
    196 			npkt = npkt->m_nextpkt;
    197 		for (; m; m = m->m_next) {
    198 			for (; offset < m->m_len; offset++, cmp++, len--) {
    199 				if (len == 0 || *cmp == '\0')
    200 					return (1);
    201 				else if (*cmp != *(mtod(m, char *) + offset))
    202 					return (0);
    203 			}
    204 			if (len == 0 || *cmp == '\0')
    205 				return (1);
    206 			offset = 0;
    207 		}
    208 	}
    209 	return (0);
    210 }
    211 
    212 #define STRSETUP(sptr, slen, str)					\
    213 	do {								\
    214 		sptr = str;						\
    215 		slen = sizeof(str) - 1;					\
    216 	} while(0)
    217 
    218 static void
    219 sohashttpget(struct socket *so, void *arg, int events, int waitflag)
    220 {
    221 
    222 	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
    223 		struct mbuf *m;
    224 		const char *cmp;
    225 		int	cmplen, cc;
    226 
    227 		m = so->so_rcv.sb_mb;
    228 		cc = so->so_rcv.sb_cc - 1;
    229 		if (cc < 1)
    230 			return;
    231 		switch (*mtod(m, char *)) {
    232 		case 'G':
    233 			STRSETUP(cmp, cmplen, "ET ");
    234 			break;
    235 		case 'H':
    236 			STRSETUP(cmp, cmplen, "EAD ");
    237 			break;
    238 		default:
    239 			goto fallout;
    240 		}
    241 		if (cc < cmplen) {
    242 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
    243 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
    244 				return;
    245 			} else {
    246 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
    247 				goto fallout;
    248 			}
    249 		}
    250 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
    251 			DPRINT("mbufstrcmp ok");
    252 			if (parse_http_version == 0)
    253 				soishttpconnected(so, arg, events, waitflag);
    254 			else
    255 				soparsehttpvers(so, arg, events, waitflag);
    256 			return;
    257 		}
    258 		DPRINT("mbufstrcmp bad");
    259 	}
    260 
    261 fallout:
    262 	DPRINT("fallout");
    263 	so->so_upcall = NULL;
    264 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    265 	soisconnected(so);
    266 	return;
    267 }
    268 
    269 static void
    270 soparsehttpvers(struct socket *so, void *arg, int events, int waitflag)
    271 {
    272 	struct mbuf *m, *n;
    273 	int	i, cc, spaces, inspaces;
    274 
    275 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    276 		goto fallout;
    277 
    278 	m = so->so_rcv.sb_mb;
    279 	cc = so->so_rcv.sb_cc;
    280 	inspaces = spaces = 0;
    281 	for (m = so->so_rcv.sb_mb; m; m = n) {
    282 		n = m->m_nextpkt;
    283 		for (; m; m = m->m_next) {
    284 			for (i = 0; i < m->m_len; i++, cc--) {
    285 				switch (*(mtod(m, char *) + i)) {
    286 				case ' ':
    287 					/* tabs? '\t' */
    288 					if (!inspaces) {
    289 						spaces++;
    290 						inspaces = 1;
    291 					}
    292 					break;
    293 				case '\r':
    294 				case '\n':
    295 					DPRINT("newline");
    296 					goto fallout;
    297 				default:
    298 					if (spaces != 2) {
    299 						inspaces = 0;
    300 						break;
    301 					}
    302 
    303 					/*
    304 					 * if we don't have enough characters
    305 					 * left (cc < sizeof("HTTP/1.0") - 1)
    306 					 * then see if the remaining ones
    307 					 * are a request we can parse.
    308 					 */
    309 					if (cc < sizeof("HTTP/1.0") - 1) {
    310 						if (mbufstrncmp(m, n, i, cc,
    311 							"HTTP/1.") == 1) {
    312 							DPRINT("ok");
    313 							goto readmore;
    314 						} else {
    315 							DPRINT("bad");
    316 							goto fallout;
    317 						}
    318 					} else if (
    319 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
    320 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
    321 						DPRINT("ok");
    322 						soishttpconnected(so,
    323 						    arg, events, waitflag);
    324 						return;
    325 					} else {
    326 						DPRINT("bad");
    327 						goto fallout;
    328 					}
    329 				}
    330 			}
    331 		}
    332 	}
    333 readmore:
    334 	DPRINT("readmore");
    335 	/*
    336 	 * if we hit here we haven't hit something
    337 	 * we don't understand or a newline, so try again
    338 	 */
    339 	so->so_upcall = soparsehttpvers;
    340 	so->so_rcv.sb_flags |= SB_UPCALL;
    341 	return;
    342 
    343 fallout:
    344 	DPRINT("fallout");
    345 	so->so_upcall = NULL;
    346 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    347 	soisconnected(so);
    348 	return;
    349 }
    350 
    351 
    352 #define NCHRS 3
    353 
    354 static void
    355 soishttpconnected(struct socket *so, void *arg, int events, int waitflag)
    356 {
    357 	char a, b, c;
    358 	struct mbuf *m, *n;
    359 	int ccleft, copied;
    360 
    361 	DPRINT("start");
    362 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    363 		goto gotit;
    364 
    365 	/*
    366 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
    367 	 * copied - how much we've copied so far
    368 	 * ccleft - how many bytes remaining in the socketbuffer
    369 	 * just loop over the mbufs subtracting from 'ccleft' until we only
    370 	 * have NCHRS left
    371 	 */
    372 	copied = 0;
    373 	ccleft = so->so_rcv.sb_cc;
    374 	if (ccleft < NCHRS)
    375 		goto readmore;
    376 	a = b = c = '\0';
    377 	for (m = so->so_rcv.sb_mb; m; m = n) {
    378 		n = m->m_nextpkt;
    379 		for (; m; m = m->m_next) {
    380 			ccleft -= m->m_len;
    381 			if (ccleft <= NCHRS) {
    382 				char *src;
    383 				int tocopy;
    384 
    385 				tocopy = (NCHRS - ccleft) - copied;
    386 				src = mtod(m, char *) + (m->m_len - tocopy);
    387 
    388 				while (tocopy--) {
    389 					switch (copied++) {
    390 					case 0:
    391 						a = *src++;
    392 						break;
    393 					case 1:
    394 						b = *src++;
    395 						break;
    396 					case 2:
    397 						c = *src++;
    398 						break;
    399 					}
    400 				}
    401 			}
    402 		}
    403 	}
    404 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
    405 		/* we have all request headers */
    406 		goto gotit;
    407 	}
    408 
    409 readmore:
    410 	so->so_upcall = soishttpconnected;
    411 	so->so_rcv.sb_flags |= SB_UPCALL;
    412 	return;
    413 
    414 gotit:
    415 	so->so_upcall = NULL;
    416 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    417 	soisconnected(so);
    418 	return;
    419 }
    420