1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 1998 Brian Somers <[email protected]> 5 * with the aid of code written by 6 * Junichi SATOH <[email protected]> 1996, 1997. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #ifdef _KERNEL 35 #include <sys/param.h> 36 #include <sys/kernel.h> 37 #include <sys/module.h> 38 #else 39 #include <errno.h> 40 #include <sys/types.h> 41 #include <stdio.h> 42 #endif 43 44 #include <netinet/in_systm.h> 45 #include <netinet/in.h> 46 #include <netinet/ip.h> 47 #include <netinet/udp.h> 48 49 #ifdef _KERNEL 50 #include <netinet/libalias/alias.h> 51 #include <netinet/libalias/alias_local.h> 52 #include <netinet/libalias/alias_mod.h> 53 #else 54 #include "alias_local.h" 55 #include "alias_mod.h" 56 #endif 57 58 #define CUSEEME_PORT_NUMBER 7648 59 60 static void 61 AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, 62 struct alias_link *lnk); 63 64 static void 65 AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip, 66 struct in_addr original_addr); 67 68 static int 69 fingerprint(struct libalias *la, struct alias_data *ah) 70 { 71 72 if (ah->dport == NULL || ah->oaddr == NULL) 73 return (-1); 74 if (ntohs(*ah->dport) == CUSEEME_PORT_NUMBER) 75 return (0); 76 return (-1); 77 } 78 79 static int 80 protohandlerin(struct libalias *la, struct ip *pip, struct alias_data *ah) 81 { 82 83 AliasHandleCUSeeMeIn(la, pip, *ah->oaddr); 84 return (0); 85 } 86 87 static int 88 protohandlerout(struct libalias *la, struct ip *pip, struct alias_data *ah) 89 { 90 91 AliasHandleCUSeeMeOut(la, pip, ah->lnk); 92 return (0); 93 } 94 95 /* Kernel module definition. */ 96 struct proto_handler handlers[] = { 97 { 98 .pri = 120, 99 .dir = OUT, 100 .proto = UDP, 101 .fingerprint = &fingerprint, 102 .protohandler = &protohandlerout 103 }, 104 { 105 .pri = 120, 106 .dir = IN, 107 .proto = UDP, 108 .fingerprint = &fingerprint, 109 .protohandler = &protohandlerin 110 }, 111 { EOH } 112 }; 113 114 static int 115 mod_handler(module_t mod, int type, void *data) 116 { 117 int error; 118 119 switch (type) { 120 case MOD_LOAD: 121 error = 0; 122 LibAliasAttachHandlers(handlers); 123 break; 124 case MOD_UNLOAD: 125 error = 0; 126 LibAliasDetachHandlers(handlers); 127 break; 128 default: 129 error = EINVAL; 130 } 131 return (error); 132 } 133 134 #ifdef _KERNEL 135 static 136 #endif 137 moduledata_t 138 alias_mod = { 139 "alias_cuseeme", mod_handler, NULL 140 }; 141 142 #ifdef _KERNEL 143 DECLARE_MODULE(alias_cuseeme, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND); 144 MODULE_VERSION(alias_cuseeme, 1); 145 MODULE_DEPEND(alias_cuseeme, libalias, 1, 1, 1); 146 #endif 147 148 /* CU-SeeMe Data Header */ 149 struct cu_header { 150 u_int16_t dest_family; 151 u_int16_t dest_port; 152 u_int32_t dest_addr; 153 int16_t family; 154 u_int16_t port; 155 u_int32_t addr; 156 u_int32_t seq; 157 u_int16_t msg; 158 u_int16_t data_type; 159 u_int16_t packet_len; 160 }; 161 162 /* Open Continue Header */ 163 struct oc_header { 164 u_int16_t client_count; /* Number of client info structs */ 165 u_int32_t seq_no; 166 char user_name [20]; 167 char reserved [4]; /* flags, version stuff, etc */ 168 }; 169 170 /* client info structures */ 171 struct client_info { 172 u_int32_t address;/* Client address */ 173 char reserved [8]; /* Flags, pruning bitfield, packet 174 * counts etc */ 175 }; 176 177 static void 178 AliasHandleCUSeeMeOut(struct libalias *la, struct ip *pip, struct alias_link *lnk) 179 { 180 struct udphdr *ud = ip_next(pip); 181 182 if (ntohs(ud->uh_ulen) - sizeof(struct udphdr) >= sizeof(struct cu_header)) { 183 struct cu_header *cu; 184 struct alias_link *cu_lnk; 185 186 cu = udp_next(ud); 187 if (cu->addr) 188 cu->addr = (u_int32_t) GetAliasAddress(lnk).s_addr; 189 190 cu_lnk = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk), 191 ud->uh_dport, 0, IPPROTO_UDP, 1); 192 193 #ifndef NO_FW_PUNCH 194 if (cu_lnk) 195 PunchFWHole(cu_lnk); 196 #endif 197 } 198 } 199 200 static void 201 AliasHandleCUSeeMeIn(struct libalias *la, struct ip *pip, struct in_addr original_addr) 202 { 203 struct in_addr alias_addr; 204 struct udphdr *ud; 205 struct cu_header *cu; 206 struct oc_header *oc; 207 struct client_info *ci; 208 char *end; 209 int i; 210 211 (void)la; 212 alias_addr.s_addr = pip->ip_dst.s_addr; 213 ud = ip_next(pip); 214 cu = udp_next(ud); 215 oc = (struct oc_header *)(cu + 1); 216 ci = (struct client_info *)(oc + 1); 217 end = (char *)ud + ntohs(ud->uh_ulen); 218 219 if ((char *)oc <= end) { 220 if (cu->dest_addr) 221 cu->dest_addr = (u_int32_t) original_addr.s_addr; 222 if (ntohs(cu->data_type) == 101) 223 /* Find and change our address */ 224 for (i = 0; (char *)(ci + 1) <= end && i < oc->client_count; i++, ci++) 225 if (ci->address == (u_int32_t) alias_addr.s_addr) { 226 ci->address = (u_int32_t) original_addr.s_addr; 227 break; 228 } 229 } 230 } 231