sys/net/libalias/alias_cuseeme.c

   1 /*-
   2  * Copyright (c) 1998 Brian Somers <brian@Awfulhak.org>
   3  * with the aid of code written by
   4  * Junichi SATOH <junichi@astec.co.jp> 1996, 1997.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *      notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *      notice, this list of conditions and the following disclaimer in the
  14  *      documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD: src/sys/netinet/libalias/alias_cuseeme.c,v 1.13.6.1 2008/11/25 02:59:29 kensmith Exp $");
  31
  32 #ifdef _KERNEL
  33 #include <sys/param.h>
  34 #include <sys/kernel.h>
  35 #include <sys/module.h>
  36 #else
  37 #include <errno.h>
  38 #include <sys/types.h>
  39 #include <stdio.h>
  40 #endif
  41
  42 #include <netinet/in_systm.h>
  43 #include <netinet/in.h>
  44 #include <netinet/ip.h>
  45 #include <netinet/udp.h>
  46
  47 #ifdef _KERNEL
  48 #include <netinet/libalias/alias.h>
  49 #include <netinet/libalias/alias_local.h>
  50 #include <netinet/libalias/alias_mod.h>
  51 #else
  52 #include "alias_local.h"
  53 #include "alias_mod.h"
  54 #endif
  55
  56 #define CUSEEME_PORT_NUMBER 7648
  57
  58 static void
  59 AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip,
  60                           struct alias_link *lnk);
  61
  62 static void
  63 AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip,
  64                          struct in_addr original_addr);
  65
  66 static int
  67 fingerprint(struct libalias *la, struct ip *pip, struct alias_data *ah)
  68 {
  69
  70         if (ah->dport == NULL || ah->oaddr == NULL)
  71                 return (-1);
  72         if (ntohs(*ah->dport) == CUSEEME_PORT_NUMBER)
  73                 return (0);
  74         return (-1);
  75 }
  76
  77 static int
  78 protohandlerin(struct libalias *la, struct ip *pip, struct alias_data *ah)
  79 {
  80
  81         AliasHandleCUSeeMeIn(la, pip, *ah->oaddr);
  82         return (0);
  83 }
  84
  85 static int
  86 protohandlerout(struct libalias *la, struct ip *pip, struct alias_data *ah)
  87 {
  88
  89         AliasHandleCUSeeMeOut(la, pip, ah->lnk);
  90         return (0);
  91 }
  92
  93 /* Kernel module definition. */
  94 struct proto_handler handlers[] = {
  95         {
  96           .pri = 120,
  97           .dir = OUT,
  98           .proto = UDP,
  99           .fingerprint = &fingerprint,
 100           .protohandler = &protohandlerout
 101         },
 102         {
 103           .pri = 120,
 104           .dir = IN,
 105           .proto = UDP,
 106           .fingerprint = &fingerprint,
 107           .protohandler = &protohandlerin
 108         },
 109         { EOH }
 110 };
 111
 112 static int
 113 mod_handler(module_t mod, int type, void *data)
 114 {
 115         int error;
 116
 117         switch (type) {
 118         case MOD_LOAD:
 119                 error = 0;
 120                 LibAliasAttachHandlers(handlers);
 121                 break;
 122         case MOD_UNLOAD:
 123                 error = 0;
 124                 LibAliasDetachHandlers(handlers);
 125                 break;
 126         default:
 127                 error = EINVAL;
 128         }
 129         return (error);
 130 }
 131
 132 #ifdef _KERNEL
 133 static
 134 #endif
 135 moduledata_t
 136 alias_mod = {
 137            "alias_cuseeme", mod_handler, NULL
 138 };
 139
 140 #ifdef  _KERNEL
 141 DECLARE_MODULE(alias_cuseeme, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
 142 MODULE_VERSION(alias_cuseeme, 1);
 143 MODULE_DEPEND(alias_cuseeme, libalias, 1, 1, 1);
 144 #endif
 145
 146 /* CU-SeeMe Data Header */
 147 struct cu_header {
 148         u_int16_t       dest_family;
 149         u_int16_t       dest_port;
 150         u_int32_t       dest_addr;
 151         int16_t         family;
 152         u_int16_t       port;
 153         u_int32_t       addr;
 154         u_int32_t       seq;
 155         u_int16_t       msg;
 156         u_int16_t       data_type;
 157         u_int16_t       packet_len;
 158 };
 159
 160 /* Open Continue Header */
 161 struct oc_header {
 162         u_int16_t       client_count;   /* Number of client info structs */
 163         u_int32_t       seq_no;
 164         char            user_name [20];
 165         char            reserved  [4];  /* flags, version stuff, etc */
 166 };
 167
 168 /* client info structures */
 169 struct client_info {
 170         u_int32_t       address;/* Client address */
 171         char            reserved  [8];  /* Flags, pruning bitfield, packet
 172                                          * counts etc */
 173 };
 174
 175 static void
 176 AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, struct alias_link *lnk)
 177 {
 178         struct udphdr *ud = ip_next(pip);
 179
 180         if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) {
 181                 struct cu_header *cu;
 182                 struct alias_link *cu_lnk;
 183
 184                 cu = udp_next(ud);
 185                 if (cu->addr)
 186                         cu->addr = (u_int32_t) GetAliasAddress(lnk).s_addr;
 187
 188                 cu_lnk = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
 189                         ud->uh_dport, 0, IPPROTO_UDP, 1);
 190
 191 #ifndef NO_FW_PUNCH
 192                 if (cu_lnk)
 193                         PunchFWHole(cu_lnk);
 194 #endif
 195         }
 196 }
 197
 198 static void
 199 AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip, struct in_addr original_addr)
 200 {
 201         struct in_addr alias_addr;
 202         struct udphdr *ud;
 203         struct cu_header *cu;
 204         struct oc_header *oc;
 205         struct client_info *ci;
 206         char *end;
 207         int i;
 208
 209         (void)la;
 210         alias_addr.s_addr = pip->ip_dst.s_addr;
 211         ud = ip_next(pip);
 212         cu = udp_next(ud);
 213         oc = (struct oc_header *)(cu + 1);
 214         ci = (struct client_info *)(oc + 1);
 215         end = (char *)ud + ntohs(ud->uh_ulen);
 216
 217         if ((char *)oc <= end) {
 218                 if (cu->dest_addr)
 219                         cu->dest_addr = (u_int32_t) original_addr.s_addr;
 220                 if (ntohs(cu->data_type) == 101)
 221                         /* Find and change our address */
 222                         for (i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++)
 223                                 if (ci->address == (u_int32_t) alias_addr.s_addr) {
 224                                         ci->address = (u_int32_t) original_addr.s_addr;
 225                                         break;
 226                                 }
 227         }
 228 }