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 static struct accept_filter accf_http_filter = { 58 "httpready", 59 sohashttpget, 60 NULL, 61 NULL 62 }; 63 64 static moduledata_t accf_http_mod = { 65 "accf_http", 66 accept_filt_generic_mod_event, 67 &accf_http_filter 68 }; 69 70 DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); 71 72 static int parse_http_version = 1; 73 74 static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, 75 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 76 "HTTP accept filter"); 77 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW, 78 &parse_http_version, 1, 79 "Parse http version so that non 1.x requests work"); 80 81 #ifdef ACCF_HTTP_DEBUG 82 #define DPRINT(fmt, args...) \ 83 do { \ 84 printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args); \ 85 } while (0) 86 #else 87 #define DPRINT(fmt, args...) 88 #endif 89 90 static int 91 sbfull(struct sockbuf *sb) 92 { 93 94 DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, " 95 "mbcnt(%ld) >= mbmax(%ld): %d", 96 sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat, 97 sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax); 98 return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax); 99 } 100 101 /* 102 * start at mbuf m, (must provide npkt if exists) 103 * starting at offset in m compare characters in mbuf chain for 'cmp' 104 */ 105 static int 106 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp) 107 { 108 struct mbuf *n; 109 110 for (; m != NULL; m = n) { 111 n = npkt; 112 if (npkt) 113 npkt = npkt->m_nextpkt; 114 for (; m; m = m->m_next) { 115 for (; offset < m->m_len; offset++, cmp++) { 116 if (*cmp == '\0') 117 return (1); 118 else if (*cmp != *(mtod(m, char *) + offset)) 119 return (0); 120 } 121 if (*cmp == '\0') 122 return (1); 123 offset = 0; 124 } 125 } 126 return (0); 127 } 128 129 /* 130 * start at mbuf m, (must provide npkt if exists) 131 * starting at offset in m compare characters in mbuf chain for 'cmp' 132 * stop at 'max' characters 133 */ 134 static int 135 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp) 136 { 137 struct mbuf *n; 138 139 for (; m != NULL; m = n) { 140 n = npkt; 141 if (npkt) 142 npkt = npkt->m_nextpkt; 143 for (; m; m = m->m_next) { 144 for (; offset < m->m_len; offset++, cmp++, max--) { 145 if (max == 0 || *cmp == '\0') 146 return (1); 147 else if (*cmp != *(mtod(m, char *) + offset)) 148 return (0); 149 } 150 if (max == 0 || *cmp == '\0') 151 return (1); 152 offset = 0; 153 } 154 } 155 return (0); 156 } 157 158 #define STRSETUP(sptr, slen, str) \ 159 do { \ 160 sptr = str; \ 161 slen = sizeof(str) - 1; \ 162 } while(0) 163 164 static int 165 sohashttpget(struct socket *so, void *arg, int waitflag) 166 { 167 168 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && 169 !sbfull(&so->so_rcv)) { 170 struct mbuf *m; 171 char *cmp; 172 int cmplen, cc; 173 174 m = so->so_rcv.sb_mb; 175 cc = sbavail(&so->so_rcv) - 1; 176 if (cc < 1) 177 return (SU_OK); 178 switch (*mtod(m, char *)) { 179 case 'G': 180 STRSETUP(cmp, cmplen, "ET "); 181 break; 182 case 'H': 183 STRSETUP(cmp, cmplen, "EAD "); 184 break; 185 default: 186 goto fallout; 187 } 188 if (cc < cmplen) { 189 if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) { 190 DPRINT("short cc (%d) but mbufstrncmp ok", cc); 191 return (SU_OK); 192 } else { 193 DPRINT("short cc (%d) mbufstrncmp failed", cc); 194 goto fallout; 195 } 196 } 197 if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) { 198 DPRINT("mbufstrcmp ok"); 199 if (parse_http_version == 0) 200 return (soishttpconnected(so, arg, waitflag)); 201 else 202 return (soparsehttpvers(so, arg, waitflag)); 203 } 204 DPRINT("mbufstrcmp bad"); 205 } 206 207 fallout: 208 DPRINT("fallout"); 209 return (SU_ISCONNECTED); 210 } 211 212 static int 213 soparsehttpvers(struct socket *so, void *arg, int waitflag) 214 { 215 struct mbuf *m, *n; 216 int i, cc, spaces, inspaces; 217 218 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv)) 219 goto fallout; 220 221 m = so->so_rcv.sb_mb; 222 cc = sbavail(&so->so_rcv); 223 inspaces = spaces = 0; 224 for (m = so->so_rcv.sb_mb; m; m = n) { 225 n = m->m_nextpkt; 226 for (; m; m = m->m_next) { 227 for (i = 0; i < m->m_len; i++, cc--) { 228 switch (*(mtod(m, char *) + i)) { 229 case ' ': 230 /* tabs? '\t' */ 231 if (!inspaces) { 232 spaces++; 233 inspaces = 1; 234 } 235 break; 236 case '\r': 237 case '\n': 238 DPRINT("newline"); 239 goto fallout; 240 default: 241 if (spaces != 2) { 242 inspaces = 0; 243 break; 244 } 245 246 /* 247 * if we don't have enough characters 248 * left (cc < sizeof("HTTP/1.0") - 1) 249 * then see if the remaining ones 250 * are a request we can parse. 251 */ 252 if (cc < sizeof("HTTP/1.0") - 1) { 253 if (mbufstrncmp(m, n, i, cc, 254 "HTTP/1.") == 1) { 255 DPRINT("ok"); 256 goto readmore; 257 } else { 258 DPRINT("bad"); 259 goto fallout; 260 } 261 } else if ( 262 mbufstrcmp(m, n, i, "HTTP/1.0") || 263 mbufstrcmp(m, n, i, "HTTP/1.1")) { 264 DPRINT("ok"); 265 return (soishttpconnected(so, 266 arg, waitflag)); 267 } else { 268 DPRINT("bad"); 269 goto fallout; 270 } 271 } 272 } 273 } 274 } 275 readmore: 276 DPRINT("readmore"); 277 /* 278 * if we hit here we haven't hit something 279 * we don't understand or a newline, so try again 280 */ 281 soupcall_set(so, SO_RCV, soparsehttpvers, arg); 282 return (SU_OK); 283 284 fallout: 285 DPRINT("fallout"); 286 return (SU_ISCONNECTED); 287 } 288 289 290 #define NCHRS 3 291 292 static int 293 soishttpconnected(struct socket *so, void *arg, int waitflag) 294 { 295 char a, b, c; 296 struct mbuf *m, *n; 297 int ccleft, copied; 298 299 DPRINT("start"); 300 if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv)) 301 goto gotit; 302 303 /* 304 * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c 305 * copied - how much we've copied so far 306 * ccleft - how many bytes remaining in the socketbuffer 307 * just loop over the mbufs subtracting from 'ccleft' until we only 308 * have NCHRS left 309 */ 310 copied = 0; 311 ccleft = sbavail(&so->so_rcv); 312 if (ccleft < NCHRS) 313 goto readmore; 314 a = b = c = '\0'; 315 for (m = so->so_rcv.sb_mb; m; m = n) { 316 n = m->m_nextpkt; 317 for (; m; m = m->m_next) { 318 ccleft -= m->m_len; 319 if (ccleft <= NCHRS) { 320 char *src; 321 int tocopy; 322 323 tocopy = (NCHRS - ccleft) - copied; 324 src = mtod(m, char *) + (m->m_len - tocopy); 325 326 while (tocopy--) { 327 switch (copied++) { 328 case 0: 329 a = *src++; 330 break; 331 case 1: 332 b = *src++; 333 break; 334 case 2: 335 c = *src++; 336 break; 337 } 338 } 339 } 340 } 341 } 342 if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) { 343 /* we have all request headers */ 344 goto gotit; 345 } 346 347 readmore: 348 soupcall_set(so, SO_RCV, soishttpconnected, arg); 349 return (SU_OK); 350 351 gotit: 352 return (SU_ISCONNECTED); 353 } 354