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accf_http.c revision 1.9 
      1 /*	$NetBSD: accf_http.c,v 1.9 2015/08/20 14:40:19 christos 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 1.9 2015/08/20 14:40:19 christos 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 static int
     84 accf_httpready_modcmd(modcmd_t cmd, void *arg)
     85 {
     86 	static struct sysctllog *clog;
     87 	int error;
     88 
     89 	switch (cmd) {
     90 	case MODULE_CMD_INIT:
     91 		error = accept_filt_add(&accf_http_filter);
     92 		if (error != 0) {
     93 			return error;
     94 		}
     95 		sysctl_createv(&clog, 0, NULL, NULL,
     96 		       CTLFLAG_PERMANENT,
     97 		       CTLTYPE_NODE, "inet", NULL,
     98 		       NULL, 0, NULL, 0,
     99 		       CTL_NET, PF_INET, CTL_EOL);
    100 		sysctl_createv(&clog, 0, NULL, NULL,
    101 		       CTLFLAG_PERMANENT,
    102 		       CTLTYPE_NODE, "accf", NULL,
    103 		       NULL, 0, NULL, 0,
    104 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
    105 		sysctl_createv(&clog, 0, NULL, NULL,
    106 		       CTLFLAG_PERMANENT,
    107 		       CTLTYPE_NODE, "http",
    108 		       SYSCTL_DESCR("HTTP accept filter"),
    109 		       NULL, 0, NULL, 0,
    110 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP, CTL_EOL);
    111 		sysctl_createv(&clog, 0, NULL, NULL,
    112 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
    113 		       CTLTYPE_INT, "parsehttpversion",
    114 		       SYSCTL_DESCR("Parse http version so that non "
    115 				    "1.x requests work"),
    116 		       NULL, 0, &parse_http_version, 0,
    117 		       CTL_NET, PF_INET, SO_ACCEPTFILTER, ACCF_HTTP,
    118 		       ACCFCTL_PARSEVER, CTL_EOL);
    119 		return 0;
    120 
    121 	case MODULE_CMD_FINI:
    122 		error = accept_filt_del(&accf_http_filter);
    123 		if (error != 0) {
    124 			return error;
    125 		}
    126 		sysctl_teardown(&clog);
    127 		return 0;
    128 
    129 	default:
    130 		return ENOTTY;
    131 	}
    132 }
    133 
    134 #ifdef ACCF_HTTP_DEBUG
    135 #define DPRINT(fmt, args...)						\
    136 	do {								\
    137 		printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args);	\
    138 	} while (0)
    139 #else
    140 #define DPRINT(fmt, args...)
    141 #endif
    142 
    143 static int
    144 sbfull(struct sockbuf *sb)
    145 {
    146 
    147 	DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
    148 	    "mbcnt(%ld) >= mbmax(%ld): %d",
    149 	    sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
    150 	    sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
    151 	return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
    152 }
    153 
    154 /*
    155  * start at mbuf m, (must provide npkt if exists)
    156  * starting at offset in m compare characters in mbuf chain for 'cmp'
    157  */
    158 static int
    159 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, const char *cmp)
    160 {
    161 	struct mbuf *n;
    162 
    163 	for (; m != NULL; m = n) {
    164 		n = npkt;
    165 		if (npkt)
    166 			npkt = npkt->m_nextpkt;
    167 		for (; m; m = m->m_next) {
    168 			for (; offset < m->m_len; offset++, cmp++) {
    169 				if (*cmp == '\0')
    170 					return (1);
    171 				else if (*cmp != *(mtod(m, char *) + offset))
    172 					return (0);
    173 			}
    174 			if (*cmp == '\0')
    175 				return (1);
    176 			offset = 0;
    177 		}
    178 	}
    179 	return (0);
    180 }
    181 
    182 /*
    183  * start at mbuf m, (must provide npkt if exists)
    184  * starting at offset in m compare characters in mbuf chain for 'cmp'
    185  * stop at 'max' characters
    186  */
    187 static int
    188 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int len, const char *cmp)
    189 {
    190 	struct mbuf *n;
    191 
    192 	for (; m != NULL; m = n) {
    193 		n = npkt;
    194 		if (npkt)
    195 			npkt = npkt->m_nextpkt;
    196 		for (; m; m = m->m_next) {
    197 			for (; offset < m->m_len; offset++, cmp++, len--) {
    198 				if (len == 0 || *cmp == '\0')
    199 					return (1);
    200 				else if (*cmp != *(mtod(m, char *) + offset))
    201 					return (0);
    202 			}
    203 			if (len == 0 || *cmp == '\0')
    204 				return (1);
    205 			offset = 0;
    206 		}
    207 	}
    208 	return (0);
    209 }
    210 
    211 #define STRSETUP(sptr, slen, str)					\
    212 	do {								\
    213 		sptr = str;						\
    214 		slen = sizeof(str) - 1;					\
    215 	} while(0)
    216 
    217 static void
    218 sohashttpget(struct socket *so, void *arg, int events, int waitflag)
    219 {
    220 
    221 	if ((so->so_state & SS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
    222 		struct mbuf *m;
    223 		const char *cmp;
    224 		int	cmplen, cc;
    225 
    226 		m = so->so_rcv.sb_mb;
    227 		cc = so->so_rcv.sb_cc - 1;
    228 		if (cc < 1)
    229 			return;
    230 		switch (*mtod(m, char *)) {
    231 		case 'G':
    232 			STRSETUP(cmp, cmplen, "ET ");
    233 			break;
    234 		case 'H':
    235 			STRSETUP(cmp, cmplen, "EAD ");
    236 			break;
    237 		default:
    238 			goto fallout;
    239 		}
    240 		if (cc < cmplen) {
    241 			if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
    242 				DPRINT("short cc (%d) but mbufstrncmp ok", cc);
    243 				return;
    244 			} else {
    245 				DPRINT("short cc (%d) mbufstrncmp failed", cc);
    246 				goto fallout;
    247 			}
    248 		}
    249 		if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
    250 			DPRINT("mbufstrcmp ok");
    251 			if (parse_http_version == 0)
    252 				soishttpconnected(so, arg, events, waitflag);
    253 			else
    254 				soparsehttpvers(so, arg, events, waitflag);
    255 			return;
    256 		}
    257 		DPRINT("mbufstrcmp bad");
    258 	}
    259 
    260 fallout:
    261 	DPRINT("fallout");
    262 	so->so_upcall = NULL;
    263 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    264 	soisconnected(so);
    265 	return;
    266 }
    267 
    268 static void
    269 soparsehttpvers(struct socket *so, void *arg, int events, int waitflag)
    270 {
    271 	struct mbuf *m, *n;
    272 	int	i, cc, spaces, inspaces;
    273 
    274 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    275 		goto fallout;
    276 
    277 	m = so->so_rcv.sb_mb;
    278 	cc = so->so_rcv.sb_cc;
    279 	inspaces = spaces = 0;
    280 	for (m = so->so_rcv.sb_mb; m; m = n) {
    281 		n = m->m_nextpkt;
    282 		for (; m; m = m->m_next) {
    283 			for (i = 0; i < m->m_len; i++, cc--) {
    284 				switch (*(mtod(m, char *) + i)) {
    285 				case ' ':
    286 					/* tabs? '\t' */
    287 					if (!inspaces) {
    288 						spaces++;
    289 						inspaces = 1;
    290 					}
    291 					break;
    292 				case '\r':
    293 				case '\n':
    294 					DPRINT("newline");
    295 					goto fallout;
    296 				default:
    297 					if (spaces != 2) {
    298 						inspaces = 0;
    299 						break;
    300 					}
    301 
    302 					/*
    303 					 * if we don't have enough characters
    304 					 * left (cc < sizeof("HTTP/1.0") - 1)
    305 					 * then see if the remaining ones
    306 					 * are a request we can parse.
    307 					 */
    308 					if (cc < sizeof("HTTP/1.0") - 1) {
    309 						if (mbufstrncmp(m, n, i, cc,
    310 							"HTTP/1.") == 1) {
    311 							DPRINT("ok");
    312 							goto readmore;
    313 						} else {
    314 							DPRINT("bad");
    315 							goto fallout;
    316 						}
    317 					} else if (
    318 					    mbufstrcmp(m, n, i, "HTTP/1.0") ||
    319 					    mbufstrcmp(m, n, i, "HTTP/1.1")) {
    320 						DPRINT("ok");
    321 						soishttpconnected(so,
    322 						    arg, events, waitflag);
    323 						return;
    324 					} else {
    325 						DPRINT("bad");
    326 						goto fallout;
    327 					}
    328 				}
    329 			}
    330 		}
    331 	}
    332 readmore:
    333 	DPRINT("readmore");
    334 	/*
    335 	 * if we hit here we haven't hit something
    336 	 * we don't understand or a newline, so try again
    337 	 */
    338 	so->so_upcall = soparsehttpvers;
    339 	so->so_rcv.sb_flags |= SB_UPCALL;
    340 	return;
    341 
    342 fallout:
    343 	DPRINT("fallout");
    344 	so->so_upcall = NULL;
    345 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    346 	soisconnected(so);
    347 	return;
    348 }
    349 
    350 
    351 #define NCHRS 3
    352 
    353 static void
    354 soishttpconnected(struct socket *so, void *arg, int events, int waitflag)
    355 {
    356 	char a, b, c;
    357 	struct mbuf *m, *n;
    358 	int ccleft, copied;
    359 
    360 	DPRINT("start");
    361 	if ((so->so_state & SS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
    362 		goto gotit;
    363 
    364 	/*
    365 	 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
    366 	 * copied - how much we've copied so far
    367 	 * ccleft - how many bytes remaining in the socketbuffer
    368 	 * just loop over the mbufs subtracting from 'ccleft' until we only
    369 	 * have NCHRS left
    370 	 */
    371 	copied = 0;
    372 	ccleft = so->so_rcv.sb_cc;
    373 	if (ccleft < NCHRS)
    374 		goto readmore;
    375 	a = b = c = '\0';
    376 	for (m = so->so_rcv.sb_mb; m; m = n) {
    377 		n = m->m_nextpkt;
    378 		for (; m; m = m->m_next) {
    379 			ccleft -= m->m_len;
    380 			if (ccleft <= NCHRS) {
    381 				char *src;
    382 				int tocopy;
    383 
    384 				tocopy = (NCHRS - ccleft) - copied;
    385 				src = mtod(m, char *) + (m->m_len - tocopy);
    386 
    387 				while (tocopy--) {
    388 					switch (copied++) {
    389 					case 0:
    390 						a = *src++;
    391 						break;
    392 					case 1:
    393 						b = *src++;
    394 						break;
    395 					case 2:
    396 						c = *src++;
    397 						break;
    398 					}
    399 				}
    400 			}
    401 		}
    402 	}
    403 	if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
    404 		/* we have all request headers */
    405 		goto gotit;
    406 	}
    407 
    408 readmore:
    409 	so->so_upcall = soishttpconnected;
    410 	so->so_rcv.sb_flags |= SB_UPCALL;
    411 	return;
    412 
    413 gotit:
    414 	so->so_upcall = NULL;
    415 	so->so_rcv.sb_flags &= ~SB_UPCALL;
    416 	soisconnected(so);
    417 	return;
    418 }
    419