The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/accf_http.c

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    1 /*-
    2  * Copyright (c) 2000 Paycounter, Inc.
    3  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  *      $FreeBSD$
   28  */
   29 
   30 #define ACCEPT_FILTER_MOD
   31 
   32 #include <sys/param.h>
   33 #include <sys/kernel.h>
   34 #include <sys/mbuf.h>
   35 #include <sys/module.h>
   36 #include <sys/signalvar.h>
   37 #include <sys/sysctl.h>
   38 #include <sys/socketvar.h>
   39 
   40 /* check for GET/HEAD */
   41 static void sohashttpget(struct socket *so, void *arg, int waitflag);
   42 /* check for HTTP/1.0 or HTTP/1.1 */
   43 static void soparsehttpvers(struct socket *so, void *arg, int waitflag);
   44 /* check for end of HTTP/1.x request */
   45 static void soishttpconnected(struct socket *so, void *arg, int waitflag);
   46 /* strcmp on an mbuf chain */
   47 static int mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp);
   48 /* strncmp on an mbuf chain */
   49 static int mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset,
   50         int max, char *cmp);
   51 /* socketbuffer is full */
   52 static int sbfull(struct sockbuf *sb);
   53 
   54 static struct accept_filter accf_http_filter = {
   55         "httpready",
   56         sohashttpget,
   57         NULL,
   58         NULL
   59 };
   60 
   61 static moduledata_t accf_http_mod = {
   62         "accf_http",
   63         accept_filt_generic_mod_event,
   64         &accf_http_filter
   65 };
   66 
   67 DECLARE_MODULE(accf_http, accf_http_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
   68 
   69 static int parse_http_version = 1;
   70 
   71 SYSCTL_NODE(_net_inet_accf, OID_AUTO, http, CTLFLAG_RW, 0,
   72 "HTTP accept filter");
   73 SYSCTL_INT(_net_inet_accf_http, OID_AUTO, parsehttpversion, CTLFLAG_RW,
   74 &parse_http_version, 1,
   75 "Parse http version so that non 1.x requests work");
   76 
   77 #ifdef ACCF_HTTP_DEBUG
   78 #define DPRINT(fmt, args...)                                            \
   79         do {                                                            \
   80                 printf("%s:%d: " fmt "\n", __func__, __LINE__, ##args); \
   81         } while (0)
   82 #else
   83 #define DPRINT(fmt, args...)
   84 #endif
   85 
   86 static int
   87 sbfull(struct sockbuf *sb)
   88 {
   89 
   90         DPRINT("sbfull, cc(%ld) >= hiwat(%ld): %d, "
   91             "mbcnt(%ld) >= mbmax(%ld): %d",
   92             sb->sb_cc, sb->sb_hiwat, sb->sb_cc >= sb->sb_hiwat,
   93             sb->sb_mbcnt, sb->sb_mbmax, sb->sb_mbcnt >= sb->sb_mbmax);
   94         return (sb->sb_cc >= sb->sb_hiwat || sb->sb_mbcnt >= sb->sb_mbmax);
   95 }
   96 
   97 /*
   98  * start at mbuf m, (must provide npkt if exists)
   99  * starting at offset in m compare characters in mbuf chain for 'cmp'
  100  */
  101 static int
  102 mbufstrcmp(struct mbuf *m, struct mbuf *npkt, int offset, char *cmp)
  103 {
  104         struct mbuf *n;
  105 
  106         for (; m != NULL; m = n) {
  107                 n = npkt;
  108                 if (npkt)
  109                         npkt = npkt->m_nextpkt;
  110                 for (; m; m = m->m_next) {
  111                         for (; offset < m->m_len; offset++, cmp++) {
  112                                 if (*cmp == '\0')
  113                                         return (1);
  114                                 else if (*cmp != *(mtod(m, char *) + offset))
  115                                         return (0);
  116                         }
  117                         if (*cmp == '\0')
  118                                 return (1);
  119                         offset = 0;
  120                 }
  121         }
  122         return (0);
  123 }
  124 
  125 /*
  126  * start at mbuf m, (must provide npkt if exists)
  127  * starting at offset in m compare characters in mbuf chain for 'cmp'
  128  * stop at 'max' characters
  129  */
  130 static int
  131 mbufstrncmp(struct mbuf *m, struct mbuf *npkt, int offset, int max, char *cmp)
  132 {
  133         struct mbuf *n;
  134 
  135         for (; m != NULL; m = n) {
  136                 n = npkt;
  137                 if (npkt)
  138                         npkt = npkt->m_nextpkt;
  139                 for (; m; m = m->m_next) {
  140                         for (; offset < m->m_len; offset++, cmp++, max--) {
  141                                 if (max == 0 || *cmp == '\0')
  142                                         return (1);
  143                                 else if (*cmp != *(mtod(m, char *) + offset))
  144                                         return (0);
  145                         }
  146                         if (max == 0 || *cmp == '\0')
  147                                 return (1);
  148                         offset = 0;
  149                 }
  150         }
  151         return (0);
  152 }
  153 
  154 #define STRSETUP(sptr, slen, str)                                       \
  155         do {                                                            \
  156                 sptr = str;                                             \
  157                 slen = sizeof(str) - 1;                                 \
  158         } while(0)
  159 
  160 static void
  161 sohashttpget(struct socket *so, void *arg, int waitflag)
  162 {
  163 
  164         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0 && !sbfull(&so->so_rcv)) {
  165                 struct mbuf *m;
  166                 char *cmp;
  167                 int     cmplen, cc;
  168 
  169                 m = so->so_rcv.sb_mb;
  170                 cc = so->so_rcv.sb_cc - 1;
  171                 if (cc < 1)
  172                         return;
  173                 switch (*mtod(m, char *)) {
  174                 case 'G':
  175                         STRSETUP(cmp, cmplen, "ET ");
  176                         break;
  177                 case 'H':
  178                         STRSETUP(cmp, cmplen, "EAD ");
  179                         break;
  180                 default:
  181                         goto fallout;
  182                 }
  183                 if (cc < cmplen) {
  184                         if (mbufstrncmp(m, m->m_nextpkt, 1, cc, cmp) == 1) {
  185                                 DPRINT("short cc (%d) but mbufstrncmp ok", cc);
  186                                 return;
  187                         } else {
  188                                 DPRINT("short cc (%d) mbufstrncmp failed", cc);
  189                                 goto fallout;
  190                         }
  191                 }
  192                 if (mbufstrcmp(m, m->m_nextpkt, 1, cmp) == 1) {
  193                         DPRINT("mbufstrcmp ok");
  194                         if (parse_http_version == 0)
  195                                 soishttpconnected(so, arg, waitflag);
  196                         else
  197                                 soparsehttpvers(so, arg, waitflag);
  198                         return;
  199                 }
  200                 DPRINT("mbufstrcmp bad");
  201         }
  202 
  203 fallout:
  204         DPRINT("fallout");
  205         so->so_upcall = NULL;
  206         so->so_rcv.sb_flags &= ~SB_UPCALL;
  207         soisconnected(so);
  208         return;
  209 }
  210 
  211 static void
  212 soparsehttpvers(struct socket *so, void *arg, int waitflag)
  213 {
  214         struct mbuf *m, *n;
  215         int     i, cc, spaces, inspaces;
  216 
  217         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
  218                 goto fallout;
  219 
  220         m = so->so_rcv.sb_mb;
  221         cc = so->so_rcv.sb_cc;
  222         inspaces = spaces = 0;
  223         for (m = so->so_rcv.sb_mb; m; m = n) {
  224                 n = m->m_nextpkt;
  225                 for (; m; m = m->m_next) {
  226                         for (i = 0; i < m->m_len; i++, cc--) {
  227                                 switch (*(mtod(m, char *) + i)) {
  228                                 case ' ':
  229                                         /* tabs? '\t' */
  230                                         if (!inspaces) {
  231                                                 spaces++;
  232                                                 inspaces = 1;
  233                                         }
  234                                         break;
  235                                 case '\r':
  236                                 case '\n':
  237                                         DPRINT("newline");
  238                                         goto fallout;
  239                                 default:
  240                                         if (spaces != 2) {
  241                                                 inspaces = 0;
  242                                                 break;
  243                                         }
  244 
  245                                         /*
  246                                          * if we don't have enough characters
  247                                          * left (cc < sizeof("HTTP/1.0") - 1)
  248                                          * then see if the remaining ones
  249                                          * are a request we can parse.
  250                                          */
  251                                         if (cc < sizeof("HTTP/1.0") - 1) {
  252                                                 if (mbufstrncmp(m, n, i, cc,
  253                                                         "HTTP/1.") == 1) {
  254                                                         DPRINT("ok");
  255                                                         goto readmore;
  256                                                 } else {
  257                                                         DPRINT("bad");
  258                                                         goto fallout;
  259                                                 }
  260                                         } else if (
  261                                             mbufstrcmp(m, n, i, "HTTP/1.0") ||
  262                                             mbufstrcmp(m, n, i, "HTTP/1.1")) {
  263                                                         DPRINT("ok");
  264                                                         soishttpconnected(so,
  265                                                             arg, waitflag);
  266                                                         return;
  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         so->so_upcall = soparsehttpvers;
  282         so->so_rcv.sb_flags |= SB_UPCALL;
  283         return;
  284 
  285 fallout:
  286         DPRINT("fallout");
  287         so->so_upcall = NULL;
  288         so->so_rcv.sb_flags &= ~SB_UPCALL;
  289         soisconnected(so);
  290         return;
  291 }
  292 
  293 
  294 #define NCHRS 3
  295 
  296 static void
  297 soishttpconnected(struct socket *so, void *arg, int waitflag)
  298 {
  299         char a, b, c;
  300         struct mbuf *m, *n;
  301         int ccleft, copied;
  302 
  303         DPRINT("start");
  304         if ((so->so_rcv.sb_state & SBS_CANTRCVMORE) != 0 || sbfull(&so->so_rcv))
  305                 goto gotit;
  306 
  307         /*
  308          * Walk the socketbuffer and copy the last NCHRS (3) into a, b, and c
  309          * copied - how much we've copied so far
  310          * ccleft - how many bytes remaining in the socketbuffer
  311          * just loop over the mbufs subtracting from 'ccleft' until we only
  312          * have NCHRS left
  313          */
  314         copied = 0;
  315         ccleft = so->so_rcv.sb_cc;
  316         if (ccleft < NCHRS)
  317                 goto readmore;
  318         a = b = c = '\0';
  319         for (m = so->so_rcv.sb_mb; m; m = n) {
  320                 n = m->m_nextpkt;
  321                 for (; m; m = m->m_next) {
  322                         ccleft -= m->m_len;
  323                         if (ccleft <= NCHRS) {
  324                                 char *src;
  325                                 int tocopy;
  326 
  327                                 tocopy = (NCHRS - ccleft) - copied;
  328                                 src = mtod(m, char *) + (m->m_len - tocopy);
  329 
  330                                 while (tocopy--) {
  331                                         switch (copied++) {
  332                                         case 0:
  333                                                 a = *src++;
  334                                                 break;
  335                                         case 1:
  336                                                 b = *src++;
  337                                                 break;
  338                                         case 2:
  339                                                 c = *src++;
  340                                                 break;
  341                                         }
  342                                 }
  343                         }
  344                 }
  345         }
  346         if (c == '\n' && (b == '\n' || (b == '\r' && a == '\n'))) {
  347                 /* we have all request headers */
  348                 goto gotit;
  349         }
  350 
  351 readmore:
  352         so->so_upcall = soishttpconnected;
  353         so->so_rcv.sb_flags |= SB_UPCALL;
  354         return;
  355 
  356 gotit:
  357         so->so_upcall = NULL;
  358         so->so_rcv.sb_flags &= ~SB_UPCALL;
  359         soisconnected(so);
  360         return;
  361 }

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