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      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 (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 1.10 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