1 /*- 2 * Copyright (c) 1998 Brian Somers <[email protected]> 3 * with the aid of code written by 4 * Junichi SATOH <[email protected]> 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("$FreeBSD$"); 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 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 } 229