sys/netinet/accf_http.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   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 #define ACCEPT_FILTER_MOD
  32
  33 #include <sys/param.h>
  34 #include <sys/kernel.h>
  35 #include <sys/mbuf.h>
  36 #include <sys/module.h>
  37 #include <sys/signalvar.h>
  38 #include <sys/sysctl.h>
  39 #include <sys/socketvar.h>
  40
  41 /* check for GET/HEAD */
  42 static int sohashttpget(struct socket *so, void *arg, int waitflag);
  43 /* check for HTTP/1.0 or HTTP/1.1 */
  44 static int soparsehttpvers(struct socket *so, void *arg, int waitflag);
  45 /* check for end of HTTP/1.x request */
  46 static int soishttpconnected(struct socket *so, void *arg, int waitflag);
  47 /* strcmp on an mbuf chain */
  48 static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
  49 /* strncmp on an mbuf chain */
  50 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
  51         int max, char *cmp);
  52 /* socketbuffer is full */
  53 static int sbfull(struct sockbuf *sb);
  54
  55 ACCEPT_FILTER_DEFINE(accf_http, "httpready", sohashttpget, NULL, NULL, 1);
  56
  57 static int parse_http_version = 1;
  58
  59 static SYSCTL_NODE(_net_inet_accf, OID_AUTO, http,
  60     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
  61     "HTTP accept filter");
  62 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
  63     &parse_http_version, 1,
  64     "Parse http version so that non 1.x requests work");
  65
  66 #ifdef ACCF_HTTP_DEBUG
  67 #define DPRINT(fmt, args...)                                            \
  68         do {                                                            \
  69                 printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args); \
  70         } while (0)
  71 #else
  72 #define DPRINT(fmt, args...)
  73 #endif
  74
  75 static int
  76 sbfull(struct sockbuf *sb)
  77 {
  78
  79         DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
  80             "mbcnt(%ld) >= mbmax(%ld): %d",
  81             sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
  82             sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
  83         return (sbused(sb) >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
  84 }
  85
  86 /*
  87  * start at mbuf m, (must provide npkt if exists)
  88  * starting at offset in m compare characters in mbuf chain for 'cmp'
  89  */
  90 static int
  91 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
  92 {
  93         struct mbuf *n;
  94
  95         for (; m != NULL; m = n) {
  96                 n = npkt;
  97                 if (npkt)
  98                         npkt = npkt->m_nextpkt;
  99                 for (; m; m = m->m_next) {
 100                         for (; offset < m->m_len; offset++, cmp++) {
 101                                 if (*cmp == '\0')
 102                                         return (1);
 103                                 else if (*cmp != *(mtod(m, char *) + offset))
 104                                         return (0);
 105                         }
 106                         if (*cmp == '\0')
 107                                 return (1);
 108                         offset = 0;
 109                 }
 110         }
 111         return (0);
 112 }
 113
 114 /*
 115  * start at mbuf m, (must provide npkt if exists)
 116  * starting at offset in m compare characters in mbuf chain for 'cmp'
 117  * stop at 'max' characters
 118  */
 119 static int
 120 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
 121 {
 122         struct mbuf *n;
 123
 124         for (; m != NULL; m = n) {
 125                 n = npkt;
 126                 if (npkt)
 127                         npkt = npkt->m_nextpkt;
 128                 for (; m; m = m->m_next) {
 129                         for (; offset < m->m_len; offset++, cmp++, max--) {
 130                                 if (max == 0 || *cmp == '\0')
 131                                         return (1);
 132                                 else if (*cmp != *(mtod(m, char *) + offset))
 133                                         return (0);
 134                         }
 135                         if (max == 0 || *cmp == '\0')
 136                                 return (1);
 137                         offset = 0;
 138                 }
 139         }
 140         return (0);
 141 }
 142
 143 #define STRSETUP(sptr, slen, str)                                       \
 144         do {                                                            \
 145                 sptr = str;                                             \
 146                 slen = sizeof(str) - 1;                                 \
 147         } while(0)
 148
 149 static int
 150 sohashttpget(struct socket *so, void *arg, int waitflag)
 151 {
 152
 153         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 &&
 154             !sbfull(&so->so_rcv)) {
 155                 struct mbuf *m;
 156                 char *cmp;
 157                 int     cmplen, cc;
 158
 159                 m = so->so_rcv.sb_mb;
 160                 cc = sbavail(&so->so_rcv) - 1;
 161                 if (cc < 1)
 162                         return (SU_OK);
 163                 switch (*mtod(m, char *)) {
 164                 case 'G':
 165                         STRSETUP(cmp, cmplen, "ET ");
 166                         break;
 167                 case 'H':
 168                         STRSETUP(cmp, cmplen, "EAD ");
 169                         break;
 170                 default:
 171                         goto fallout;
 172                 }
 173                 if (cc < cmplen) {
 174                         if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
 175                                 DPRINT("short cc (%d) but mbufstrncmp ok", cc);
 176                                 return (SU_OK);
 177                         } else {
 178                                 DPRINT("short cc (%d) mbufstrncmp failed", cc);
 179                                 goto fallout;
 180                         }
 181                 }
 182                 if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
 183                         DPRINT("mbufstrcmp ok");
 184                         if (parse_http_version == 0)
 185                                 return (soishttpconnected(so, arg, waitflag));
 186                         else
 187                                 return (soparsehttpvers(so, arg, waitflag));
 188                 }
 189                 DPRINT("mbufstrcmp bad");
 190         }
 191
 192 fallout:
 193         DPRINT("fallout");
 194         return (SU_ISCONNECTED);
 195 }
 196
 197 static int
 198 soparsehttpvers(struct socket *so, void *arg, int waitflag)
 199 {
 200         struct mbuf *m, *n;
 201         int     i, cc, spaces, inspaces;
 202
 203         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
 204                 goto fallout;
 205
 206         m = so->so_rcv.sb_mb;
 207         cc = sbavail(&so->so_rcv);
 208         inspaces = spaces = 0;
 209         for (m = so->so_rcv.sb_mb; m; m = n) {
 210                 n = m->m_nextpkt;
 211                 for (; m; m = m->m_next) {
 212                         for (i = 0; i < m->m_len; i++, cc--) {
 213                                 switch (*(mtod(m, char *) + i)) {
 214                                 case ' ':
 215                                         /* tabs? '\t' */
 216                                         if (!inspaces) {
 217                                                 spaces++;
 218                                                 inspaces = 1;
 219                                         }
 220                                         break;
 221                                 case '\r':
 222                                 case '\n':
 223                                         DPRINT("newline");
 224                                         goto fallout;
 225                                 default:
 226                                         if (spaces != 2) {
 227                                                 inspaces = 0;
 228                                                 break;
 229                                         }
 230
 231                                         /*
 232                                          * if we don't have enough characters
 233                                          * left (cc < sizeof("HTTP/1.0") - 1)
 234                                          * then see if the remaining ones
 235                                          * are a request we can parse.
 236                                          */
 237                                         if (cc < sizeof("HTTP/1.0") - 1) {
 238                                                 if (mbufstrncmp(m, n, i, cc,
 239                                                         "HTTP/1.") == 1) {
 240                                                         DPRINT("ok");
 241                                                         goto readmore;
 242                                                 } else {
 243                                                         DPRINT("bad");
 244                                                         goto fallout;
 245                                                 }
 246                                         } else if (
 247                                             mbufstrcmp(m, n, i, "HTTP/1.0") ||
 248                                             mbufstrcmp(m, n, i, "HTTP/1.1")) {
 249                                                 DPRINT("ok");
 250                                                 return (soishttpconnected(so,
 251                                                     arg, waitflag));
 252                                         } else {
 253                                                 DPRINT("bad");
 254                                                 goto fallout;
 255                                         }
 256                                 }
 257                         }
 258                 }
 259         }
 260 readmore:
 261         DPRINT("readmore");
 262         /*
 263          * if we hit here we haven't hit something
 264          * we don't understand or a newline, so try again
 265          */
 266         soupcall_set(so, SO_RCV, soparsehttpvers, arg);
 267         return (SU_OK);
 268
 269 fallout:
 270         DPRINT("fallout");
 271         return (SU_ISCONNECTED);
 272 }
 273
 274 #define NCHRS 3
 275
 276 static int
 277 soishttpconnected(struct socket *so, void *arg, int waitflag)
 278 {
 279         char a, b, c;
 280         struct mbuf *m, *n;
 281         int ccleft, copied;
 282
 283         DPRINT("start");
 284         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
 285                 goto gotit;
 286
 287         /*
 288          * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
 289          * copied - how much we've copied so far
 290          * ccleft - how many bytes remaining in the socketbuffer
 291          * just loop over the mbufs subtracting from 'ccleft' until we only
 292          * have NCHRS left
 293          */
 294         copied = 0;
 295         ccleft = sbavail(&so->so_rcv);
 296         if (ccleft < NCHRS)
 297                 goto readmore;
 298         a = b = c = '\0';
 299         for (m = so->so_rcv.sb_mb; m; m = n) {
 300                 n = m->m_nextpkt;
 301                 for (; m; m = m->m_next) {
 302                         ccleft -= m->m_len;
 303                         if (ccleft <= NCHRS) {
 304                                 char *src;
 305                                 int tocopy;
 306
 307                                 tocopy = (NCHRS - ccleft) - copied;
 308                                 src = mtod(m, char *) + (m->m_len - tocopy);
 309
 310                                 while (tocopy--) {
 311                                         switch (copied++) {
 312                                         case 0:
 313                                                 a = *src++;
 314                                                 break;
 315                                         case 1:
 316                                                 b = *src++;
 317                                                 break;
 318                                         case 2:
 319                                                 c = *src++;
 320                                                 break;
 321                                         }
 322                                 }
 323                         }
 324                 }
 325         }
 326         if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
 327                 /* we have all request headers */
 328                 goto gotit;
 329         }
 330
 331 readmore:
 332         soupcall_set(so, SO_RCV, soishttpconnected, arg);
 333         return (SU_OK);
 334
 335 gotit:
 336         return (SU_ISCONNECTED);
 337 }