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accf_http.c revision 1.1.2.2 
      1 /*-
      2  * Copyright (c) 2000 Paycounter, Inc.
      3  * Author: Alfred Perlstein <alfred (at) paycounter.com>, <alfred (at) 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 __KERNEL_RCSID(0, "$NetBSD: accf_http.c,v 1.1.2.2 2008/09/18 04:37:00 wrstuden Exp $");
     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/lkm.h>
     37 #include <sys/signalvar.h>
     38 #include <sys/sysctl.h>
     39 #include <sys/socket.h>
     40 #include <sys/socketvar.h>
     41 #include <netinet/accept_filter.h>
     42 
     43 /* check for GET/HEAD */
     44 static void sohashttpget(struct socket *so, void *arg, int waitflag);
     45 /* check for HTTP/1.0 or HTTP/1.1 */
     46 static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
     47 /* check for end of HTTP/1.x request */
     48 static void 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, const char *cmp);
     51 /* strncmp on an mbuf chain */
     52 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
     53 	int len, const 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 	{NULL,}
     63 };
     64 
     65 /*
     66  * Names of HTTP Accept filter sysctl objects
     67  */
     68 
     69 #define ACCFCTL_PARSEVER	1	/* Parse HTTP version */
     70 
     71 static int parse_http_version = 1;
     72 
     73 SYSCTL_SETUP(sysctl_net_inet_accf__http_setup, "sysctl net.inet.accf.http subtree setup")
     74 {
     75 	sysctl_createv(clog, 0, NULL, NULL,
     76 		       CTLFLAG_PERMANENT,
     77 		       CTLTYPE_NODE, "net", NULL,
     78 		       NULL, 0, NULL, 0,
     79 		       CTL_NET, CTL_EOL);
     80 	sysctl_createv(clog, 0, NULL, NULL,
     81 		       CTLFLAG_PERMANENT,
     82 		       CTLTYPE_NODE, "inet", NULL,
     83 		       NULL, 0, NULL, 0,
     84 		       CTL_NET, PF_INET, CTL_EOL);
     85 	sysctl_createv(clog, 0, NULL, NULL,
     86 		       CTLFLAG_PERMANENT,
     87 		       CTLTYPE_NODE, "accf", NULL,
     88 		       NULL, 0, NULL, 0,
     89 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
     90 	sysctl_createv(clog, 0, NULL, NULL,
     91 		       CTLFLAG_PERMANENT,
     92 		       CTLTYPE_NODE, "http",
     93 		       SYSCTL_DESCR("HTTP accept filter"),
     94 		       NULL, 0, NULL, 0,
     95 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP, CTL_EOL);
     96 	sysctl_createv(clog, 0, NULL, NULL,
     97 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
     98 		       CTLTYPE_INT, "parsehttpversion",
     99 		       SYSCTL_DESCR("Parse http version so that non "
    100 				    "1.x requests work"),
    101 		       NULL, 0, &parse_http_version, 0,
    102 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP,
    103 		       ACCFCTL_PARSEVER, CTL_EOL);
    104 }
    105 
    106 void accf_httpattach(int);
    107 void accf_httpattach(int num)
    108 {
    109 	accept_filt_generic_mod_event(NULL, LKM_E_LOAD, &accf_http_filter);
    110 }
    111 
    112 /*
    113  * This code is to make HTTP ready accept filer as LKM.
    114  * To compile as LKM we need to move this set of code into
    115  * another file and include this file for compilation when
    116  * making LKM
    117  */
    118 
    119 #ifdef _LKM
    120 static int accf_http_handle(struct lkm_table * lkmtp, int cmd);
    121 int accf_http_lkmentry(struct lkm_table * lkmtp, int cmd, int ver);
    122 
    123 MOD_MISC("accf_http");
    124 
    125 static int accf_http_handle(struct lkm_table * lkmtp, int cmd)
    126 {
    127 
    128 	return accept_filt_generic_mod_event(lkmtp, cmd, &accf_http_filter);
    129 }
    130 
    131 /*
    132  * the module entry point.
    133  */
    134 int
    135 accf_http_lkmentry(struct lkm_table *lkmtp, int cmd, int ver)
    136 {
    137 	DISPATCH(lkmtp, cmd, ver, accf_http_handle, accf_http_handle,
    138 	    accf_http_handle)
    139 }
    140 #endif
    141 
    142 #ifdef ACCF_HTTP_DEBUG
    143 #define DPRINT(fmt, args...)						\
    144 	do {								\
    145 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
    146 	} while (0)
    147 #else
    148 #define DPRINT(fmt, args...)
    149 #endif
    150 
    151 static int
    152 sbfull(struct sockbuf *sb)
    153 {
    154 
    155 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
    156 	    "mbcnt(%ld) >= mbmax(%ld): %d",
    157 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
    158 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
    159 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
    160 }
    161 
    162 /*
    163  * start at mbuf m, (must provide npkt if exists)
    164  * starting at offset in m compare characters in mbuf chain for 'cmp'
    165  */
    166 static int
    167 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp)
    168 {
    169 	struct mbuf *n;
    170 
    171 	for (; m != NULL; m = n) {
    172 		n = npkt;
    173 		if (npkt)
    174 			npkt = npkt->m_nextpkt;
    175 		for (; m; m = m->m_next) {
    176 			for (; offset < m->m_len; offset++, cmp++) {
    177 				if (*cmp == '\0')
    178 					return (1);
    179 				else if (*cmp != *(mtod(m, char *) + offset))
    180 					return (0);
    181 			}
    182 			if (*cmp == '\0')
    183 				return (1);
    184 			offset = 0;
    185 		}
    186 	}
    187 	return (0);
    188 }
    189 
    190 /*
    191  * start at mbuf m, (must provide npkt if exists)
    192  * starting at offset in m compare characters in mbuf chain for 'cmp'
    193  * stop at 'max' characters
    194  */
    195 static int
    196 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int len, const char *cmp)
    197 {
    198 	struct mbuf *n;
    199 
    200 	for (; m != NULL; m = n) {
    201 		n = npkt;
    202 		if (npkt)
    203 			npkt = npkt->m_nextpkt;
    204 		for (; m; m = m->m_next) {
    205 			for (; offset < m->m_len; offset++, cmp++, len--) {
    206 				if (len == 0 || *cmp == '\0')
    207 					return (1);
    208 				else if (*cmp != *(mtod(m, char *) + offset))
    209 					return (0);
    210 			}
    211 			if (len == 0 || *cmp == '\0')
    212 				return (1);
    213 			offset = 0;
    214 		}
    215 	}
    216 	return (0);
    217 }
    218 
    219 #define STRSETUP(sptr, slen, str)					\
    220 	do {								\
    221 		sptr = str;						\
    222 		slen = sizeof(str) - 1;					\
    223 	} while(0)
    224 
    225 static void
    226 sohashttpget(struct socket *so, void *arg, int waitflag)
    227 {
    228 
    229 	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
    230 		struct mbuf *m;
    231 		const char *cmp;
    232 		int	cmplen, cc;
    233 
    234 		m = so->so_rcv.sb_mb;
    235 		cc = so->so_rcv.sb_cc - 1;
    236 		if (cc < 1)
    237 			return;
    238 		switch (*mtod(m, char *)) {
    239 		case 'G':
    240 			STRSETUP(cmp, cmplen, "ET ");
    241 			break;
    242 		case 'H':
    243 			STRSETUP(cmp, cmplen, "EAD ");
    244 			break;
    245 		default:
    246 			goto fallout;
    247 		}
    248 		if (cc < cmplen) {
    249 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
    250 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
    251 				return;
    252 			} else {
    253 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
    254 				goto fallout;
    255 			}
    256 		}
    257 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
    258 			DPRINT("mbufstrcmp ok");
    259 			if (parse_http_version == 0)
    260 				soishttpconnected(so, arg, waitflag);
    261 			else
    262 				soparsehttpvers(so, arg, waitflag);
    263 			return;
    264 		}
    265 		DPRINT("mbufstrcmp bad");
    266 	}
    267 
    268 fallout:
    269 	DPRINT("fallout");
    270 	so->so_upcall = NULL;
    271 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    272 	soisconnected(so);
    273 	return;
    274 }
    275 
    276 static void
    277 soparsehttpvers(struct socket *so, void *arg, int waitflag)
    278 {
    279 	struct mbuf *m, *n;
    280 	int	i, cc, spaces, inspaces;
    281 
    282 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    283 		goto fallout;
    284 
    285 	m = so->so_rcv.sb_mb;
    286 	cc = so->so_rcv.sb_cc;
    287 	inspaces = spaces = 0;
    288 	for (m = so->so_rcv.sb_mb; m; m = n) {
    289 		n = m->m_nextpkt;
    290 		for (; m; m = m->m_next) {
    291 			for (i = 0; i < m->m_len; i++, cc--) {
    292 				switch (*(mtod(m, char *) + i)) {
    293 				case ' ':
    294 					/* tabs? '\t' */
    295 					if (!inspaces) {
    296 						spaces++;
    297 						inspaces = 1;
    298 					}
    299 					break;
    300 				case '\r':
    301 				case '\n':
    302 					DPRINT("newline");
    303 					goto fallout;
    304 				default:
    305 					if (spaces != 2) {
    306 						inspaces = 0;
    307 						break;
    308 					}
    309 
    310 					/*
    311 					 * if we don't have enough characters
    312 					 * left (cc < sizeof("HTTP/1.0") - 1)
    313 					 * then see if the remaining ones
    314 					 * are a request we can parse.
    315 					 */
    316 					if (cc < sizeof("HTTP/1.0") - 1) {
    317 						if (mbufstrncmp(m, n, i, cc,
    318 							"HTTP/1.") == 1) {
    319 							DPRINT("ok");
    320 							goto readmore;
    321 						} else {
    322 							DPRINT("bad");
    323 							goto fallout;
    324 						}
    325 					} else if (
    326 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
    327 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
    328 							DPRINT("ok");
    329 							soishttpconnected(so,
    330 							    arg, waitflag);
    331 							return;
    332 					} else {
    333 						DPRINT("bad");
    334 						goto fallout;
    335 					}
    336 				}
    337 			}
    338 		}
    339 	}
    340 readmore:
    341 	DPRINT("readmore");
    342 	/*
    343 	 * if we hit here we haven't hit something
    344 	 * we don't understand or a newline, so try again
    345 	 */
    346 	so->so_upcall = soparsehttpvers;
    347 	so->so_rcv.sb_flags |= SB_UPCALL;
    348 	return;
    349 
    350 fallout:
    351 	DPRINT("fallout");
    352 	so->so_upcall = NULL;
    353 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    354 	soisconnected(so);
    355 	return;
    356 }
    357 
    358 
    359 #define NCHRS 3
    360 
    361 static void
    362 soishttpconnected(struct socket *so, void *arg, int waitflag)
    363 {
    364 	char a, b, c;
    365 	struct mbuf *m, *n;
    366 	int ccleft, copied;
    367 
    368 	DPRINT("start");
    369 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    370 		goto gotit;
    371 
    372 	/*
    373 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
    374 	 * copied - how much we've copied so far
    375 	 * ccleft - how many bytes remaining in the socketbuffer
    376 	 * just loop over the mbufs subtracting from 'ccleft' until we only
    377 	 * have NCHRS left
    378 	 */
    379 	copied = 0;
    380 	ccleft = so->so_rcv.sb_cc;
    381 	if (ccleft < NCHRS)
    382 		goto readmore;
    383 	a = b = c = '\0';
    384 	for (m = so->so_rcv.sb_mb; m; m = n) {
    385 		n = m->m_nextpkt;
    386 		for (; m; m = m->m_next) {
    387 			ccleft -= m->m_len;
    388 			if (ccleft <= NCHRS) {
    389 				char *src;
    390 				int tocopy;
    391 
    392 				tocopy = (NCHRS - ccleft) - copied;
    393 				src = mtod(m, char *) + (m->m_len - tocopy);
    394 
    395 				while (tocopy--) {
    396 					switch (copied++) {
    397 					case 0:
    398 						a = *src++;
    399 						break;
    400 					case 1:
    401 						b = *src++;
    402 						break;
    403 					case 2:
    404 						c = *src++;
    405 						break;
    406 					}
    407 				}
    408 			}
    409 		}
    410 	}
    411 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
    412 		/* we have all request headers */
    413 		goto gotit;
    414 	}
    415 
    416 readmore:
    417 	so->so_upcall = soishttpconnected;
    418 	so->so_rcv.sb_flags |= SB_UPCALL;
    419 	return;
    420 
    421 gotit:
    422 	so->so_upcall = NULL;
    423 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    424 	soisconnected(so);
    425 	return;
    426 }
    427