1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2000 Paycounter, Inc. 5 * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@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 __FBSDID("$FreeBSD$"); 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/socketvar.h> 42 43 /* check for GET/HEAD */ 44 static int sohashttpget(struct socket *so, void *arg, int waitflag); 45 /* check for HTTP/1.0 or HTTP/1.1 */ 46 static int soparsehttpvers(struct socket *so, void *arg, int waitflag); 47 /* check for end of HTTP/1.x request */ 48 static int 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, char *cmp); 51 /* strncmp on an mbuf chain */ 52 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, 53 int max, char *cmp); 54 /* socketbuffer is full */ 55 static int sbfull(struct sockbuf *sb); 56 57 ACCEPT_FILTER_DEFINE(accf_http, "httpready", sohashttpget, NULL, NULL, 1); 58 59 static int parse_http_version = 1; 60 61 static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, 62 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 63 "HTTP accept filter"); 64 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW, 65 &parse_http_version, 1, 66 "Parse http version so that non 1.x requests work"); 67 68 #ifdef ACCF_HTTP_DEBUG 69 #define DPRINT(fmt, args...) \ 70 do { \ 71 printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args); \ 72 } while (0) 73 #else 74 #define DPRINT(fmt, args...) 75 #endif 76 77 static int 78 sbfull(struct sockbuf *sb) 79 { 80 81 DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, " 82 "mbcnt(%ld) >= mbmax(%ld): %d", 83 sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat, 84 sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax); 85 return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax); 86 } 87 88 /* 89 * start at mbuf m, (must provide npkt if exists) 90 * starting at offset in m compare characters in mbuf chain for 'cmp' 91 */ 92 static int 93 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp) 94 { 95 struct mbuf *n; 96 97 for (; m != NULL; m = n) { 98 n = npkt; 99 if (npkt) 100 npkt = npkt->m_nextpkt; 101 for (; m; m = m->m_next) { 102 for (; offset < m->m_len; offset++, cmp++) { 103 if (*cmp == '\0') 104 return (1); 105 else if (*cmp != *(mtod(m, char *) + offset)) 106 return (0); 107 } 108 if (*cmp == '\0') 109 return (1); 110 offset = 0; 111 } 112 } 113 return (0); 114 } 115 116 /* 117 * start at mbuf m, (must provide npkt if exists) 118 * starting at offset in m compare characters in mbuf chain for 'cmp' 119 * stop at 'max' characters 120 */ 121 static int 122 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp) 123 { 124 struct mbuf *n; 125 126 for (; m != NULL; m = n) { 127 n = npkt; 128 if (npkt) 129 npkt = npkt->m_nextpkt; 130 for (; m; m = m->m_next) { 131 for (; offset < m->m_len; offset++, cmp++, max--) { 132 if (max == 0 || *cmp == '\0') 133 return (1); 134 else if (*cmp != *(mtod(m, char *) + offset)) 135 return (0); 136 } 137 if (max == 0 || *cmp == '\0') 138 return (1); 139 offset = 0; 140 } 141 } 142 return (0); 143 } 144 145 #define STRSETUP(sptr, slen, str) \ 146 do { \ 147 sptr = str; \ 148 slen = sizeof(str) - 1; \ 149 } while(0) 150 151 static int 152 sohashttpget(struct socket *so, void *arg, int waitflag) 153 { 154 155 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && 156 !sbfull(&so->so_rcv)) { 157 struct mbuf *m; 158 char *cmp; 159 int cmplen, cc; 160 161 m = so->so_rcv.sb_mb; 162 cc = sbavail(&so->so_rcv) - 1; 163 if (cc < 1) 164 return (SU_OK); 165 switch (*mtod(m, char *)) { 166 case 'G': 167 STRSETUP(cmp, cmplen, "ET "); 168 break; 169 case 'H': 170 STRSETUP(cmp, cmplen, "EAD "); 171 break; 172 default: 173 goto fallout; 174 } 175 if (cc < cmplen) { 176 if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) { 177 DPRINT("short cc (%d) but mbufstrncmp ok", cc); 178 return (SU_OK); 179 } else { 180 DPRINT("short cc (%d) mbufstrncmp failed", cc); 181 goto fallout; 182 } 183 } 184 if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) { 185 DPRINT("mbufstrcmp ok"); 186 if (parse_http_version == 0) 187 return (soishttpconnected(so, arg, waitflag)); 188 else 189 return (soparsehttpvers(so, arg, waitflag)); 190 } 191 DPRINT("mbufstrcmp bad"); 192 } 193 194 fallout: 195 DPRINT("fallout"); 196 return (SU_ISCONNECTED); 197 } 198 199 static int 200 soparsehttpvers(struct socket *so, void *arg, int waitflag) 201 { 202 struct mbuf *m, *n; 203 int i, cc, spaces, inspaces; 204 205 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv)) 206 goto fallout; 207 208 m = so->so_rcv.sb_mb; 209 cc = sbavail(&so->so_rcv); 210 inspaces = spaces = 0; 211 for (m = so->so_rcv.sb_mb; m; m = n) { 212 n = m->m_nextpkt; 213 for (; m; m = m->m_next) { 214 for (i = 0; i < m->m_len; i++, cc--) { 215 switch (*(mtod(m, char *) + i)) { 216 case ' ': 217 /* tabs? '\t' */ 218 if (!inspaces) { 219 spaces++; 220 inspaces = 1; 221 } 222 break; 223 case '\r': 224 case '\n': 225 DPRINT("newline"); 226 goto fallout; 227 default: 228 if (spaces != 2) { 229 inspaces = 0; 230 break; 231 } 232 233 /* 234 * if we don't have enough characters 235 * left (cc < sizeof("HTTP/1.0") - 1) 236 * then see if the remaining ones 237 * are a request we can parse. 238 */ 239 if (cc < sizeof("HTTP/1.0") - 1) { 240 if (mbufstrncmp(m, n, i, cc, 241 "HTTP/1.") == 1) { 242 DPRINT("ok"); 243 goto readmore; 244 } else { 245 DPRINT("bad"); 246 goto fallout; 247 } 248 } else if ( 249 mbufstrcmp(m, n, i, "HTTP/1.0") || 250 mbufstrcmp(m, n, i, "HTTP/1.1")) { 251 DPRINT("ok"); 252 return (soishttpconnected(so, 253 arg, waitflag)); 254 } else { 255 DPRINT("bad"); 256 goto fallout; 257 } 258 } 259 } 260 } 261 } 262 readmore: 263 DPRINT("readmore"); 264 /* 265 * if we hit here we haven't hit something 266 * we don't understand or a newline, so try again 267 */ 268 soupcall_set(so, SO_RCV, soparsehttpvers, arg); 269 return (SU_OK); 270 271 fallout: 272 DPRINT("fallout"); 273 return (SU_ISCONNECTED); 274 } 275 276 #define NCHRS 3 277 278 static int 279 soishttpconnected(struct socket *so, void *arg, int waitflag) 280 { 281 char a, b, c; 282 struct mbuf *m, *n; 283 int ccleft, copied; 284 285 DPRINT("start"); 286 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv)) 287 goto gotit; 288 289 /* 290 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c 291 * copied - how much we've copied so far 292 * ccleft - how many bytes remaining in the socketbuffer 293 * just loop over the mbufs subtracting from 'ccleft' until we only 294 * have NCHRS left 295 */ 296 copied = 0; 297 ccleft = sbavail(&so->so_rcv); 298 if (ccleft < NCHRS) 299 goto readmore; 300 a = b = c = '\0'; 301 for (m = so->so_rcv.sb_mb; m; m = n) { 302 n = m->m_nextpkt; 303 for (; m; m = m->m_next) { 304 ccleft -= m->m_len; 305 if (ccleft <= NCHRS) { 306 char *src; 307 int tocopy; 308 309 tocopy = (NCHRS - ccleft) - copied; 310 src = mtod(m, char *) + (m->m_len - tocopy); 311 312 while (tocopy--) { 313 switch (copied++) { 314 case 0: 315 a = *src++; 316 break; 317 case 1: 318 b = *src++; 319 break; 320 case 2: 321 c = *src++; 322 break; 323 } 324 } 325 } 326 } 327 } 328 if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) { 329 /* we have all request headers */ 330 goto gotit; 331 } 332 333 readmore: 334 soupcall_set(so, SO_RCV, soishttpconnected, arg); 335 return (SU_OK); 336 337 gotit: 338 return (SU_ISCONNECTED); 339 } 340