1 /*- 2 * alias_skinny.c 3 * 4 * Copyright (c) 2002, 2003 MarcusCom, Inc. 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 * Author: Joe Marcus Clarke <marcus@FreeBSD.org> 29 * 30 * $FreeBSD$ 31 */ 32 33 #include <stdio.h> 34 #include <string.h> 35 #include <sys/types.h> 36 #include <sys/socket.h> 37 #include <netinet/in_systm.h> 38 #include <netinet/in.h> 39 #include <arpa/inet.h> 40 #include <netinet/ip.h> 41 #include <netinet/tcp.h> 42 #include <netinet/udp.h> 43 #include <unistd.h> 44 45 #include "alias_local.h" 46 47 /* 48 * alias_skinny.c handles the translation for the Cisco Skinny Station 49 * protocol. Skinny typically uses TCP port 2000 to set up calls between 50 * a Cisco Call Manager and a Cisco IP phone. When a phone comes on line, 51 * it first needs to register with the Call Manager. To do this it sends 52 * a registration message. This message contains the IP address of the 53 * IP phone. This message must then be translated to reflect our global 54 * IP address. Along with the registration message (and usually in the 55 * same packet), the phone sends an IP port message. This message indicates 56 * the TCP port over which it will communicate. 57 * 58 * When a call is placed from the phone, the Call Manager will send an 59 * Open Receive Channel message to the phone to let the caller know someone 60 * has answered. The phone then sends back an Open Receive Channel 61 * Acknowledgement. In this packet, the phone sends its IP address again, 62 * and the UDP port over which the voice traffic should flow. These values 63 * need translation. Right after the Open Receive Channel Acknowledgement, 64 * the Call Manager sends a Start Media Transmission message indicating the 65 * call is connected. This message contains the IP address and UDP port 66 * number of the remote (called) party. Once this message is translated, the 67 * call can commence. The called part sends the first UDP packet to the 68 * calling phone at the pre-arranged UDP port in the Open Receive Channel 69 * Acknowledgement. 70 * 71 * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems, 72 * Inc. All rights reserved. 73 */ 74 75 /* #define DEBUG 1 */ 76 77 /* Message types that need translating */ 78 #define REG_MSG 0x00000001 79 #define IP_PORT_MSG 0x00000002 80 #define OPNRCVCH_ACK 0x00000022 81 #define START_MEDIATX 0x0000008a 82 83 struct skinny_header { 84 u_int32_t len; 85 u_int32_t reserved; 86 u_int32_t msgId; 87 }; 88 89 struct RegisterMessage { 90 u_int32_t msgId; 91 char devName [16]; 92 u_int32_t uid; 93 u_int32_t instance; 94 u_int32_t ipAddr; 95 u_char devType; 96 u_int32_t maxStreams; 97 }; 98 99 struct IpPortMessage { 100 u_int32_t msgId; 101 u_int32_t stationIpPort; /* Note: Skinny uses 32-bit port 102 * numbers */ 103 }; 104 105 struct OpenReceiveChannelAck { 106 u_int32_t msgId; 107 u_int32_t status; 108 u_int32_t ipAddr; 109 u_int32_t port; 110 u_int32_t passThruPartyID; 111 }; 112 113 struct StartMediaTransmission { 114 u_int32_t msgId; 115 u_int32_t conferenceID; 116 u_int32_t passThruPartyID; 117 u_int32_t remoteIpAddr; 118 u_int32_t remotePort; 119 u_int32_t MSPacket; 120 u_int32_t payloadCap; 121 u_int32_t precedence; 122 u_int32_t silenceSuppression; 123 u_short maxFramesPerPacket; 124 u_int32_t G723BitRate; 125 }; 126 127 typedef enum { 128 ClientToServer = 0, 129 ServerToClient = 1 130 } ConvDirection; 131 132 133 static int 134 alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip, 135 struct tcphdr *tc, struct alias_link *link, 136 ConvDirection direction) 137 { 138 reg_msg->ipAddr = (u_int32_t) GetAliasAddress(link).s_addr; 139 140 tc->th_sum = 0; 141 tc->th_sum = TcpChecksum(pip); 142 143 return 0; 144 } 145 146 static int 147 alias_skinny_startmedia(struct StartMediaTransmission *start_media, 148 struct ip *pip, struct tcphdr *tc, 149 struct alias_link *link, u_int32_t localIpAddr, 150 ConvDirection direction) 151 { 152 struct in_addr dst, src; 153 154 dst.s_addr = start_media->remoteIpAddr; 155 src.s_addr = localIpAddr; 156 157 /* 158 * XXX I should probably handle in bound global translations as 159 * well. 160 */ 161 162 return 0; 163 } 164 165 static int 166 alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip, 167 struct tcphdr *tc, struct alias_link *link, 168 ConvDirection direction) 169 { 170 port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(link)); 171 172 tc->th_sum = 0; 173 tc->th_sum = TcpChecksum(pip); 174 175 return 0; 176 } 177 178 static int 179 alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack, 180 struct ip *pip, struct tcphdr *tc, 181 struct alias_link *link, u_int32_t * localIpAddr, 182 ConvDirection direction) 183 { 184 struct in_addr null_addr; 185 struct alias_link *opnrcv_link; 186 u_int32_t localPort; 187 188 *localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr; 189 localPort = opnrcvch_ack->port; 190 191 null_addr.s_addr = INADDR_ANY; 192 opnrcv_link = FindUdpTcpOut(la, pip->ip_src, null_addr, 193 htons((u_short) opnrcvch_ack->port), 0, 194 IPPROTO_UDP, 1); 195 opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_link).s_addr; 196 opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_link)); 197 198 tc->th_sum = 0; 199 tc->th_sum = TcpChecksum(pip); 200 201 return 0; 202 } 203 204 void 205 AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *link) 206 { 207 int hlen, tlen, dlen; 208 struct tcphdr *tc; 209 u_int32_t msgId, len, t, lip; 210 struct skinny_header *sd; 211 int orig_len, skinny_hdr_len = sizeof(struct skinny_header); 212 ConvDirection direction; 213 214 tc = (struct tcphdr *)((char *)pip + (pip->ip_hl << 2)); 215 hlen = (pip->ip_hl + tc->th_off) << 2; 216 tlen = ntohs(pip->ip_len); 217 dlen = tlen - hlen; 218 219 sd = (struct skinny_header *)((char *)pip + hlen); 220 221 /* 222 * XXX This direction is reserved for future use. I still need to 223 * handle the scenario where the call manager is on the inside, and 224 * the calling phone is on the global outside. 225 */ 226 if (ntohs(tc->th_dport) == la->skinnyPort) { 227 direction = ClientToServer; 228 } else if (ntohs(tc->th_sport) == la->skinnyPort) { 229 direction = ServerToClient; 230 } else { 231 #ifdef DEBUG 232 fprintf(stderr, 233 "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n"); 234 #endif 235 return; 236 } 237 238 orig_len = dlen; 239 /* 240 * Skinny packets can contain many messages. We need to loop 241 * through the packet using len to determine message boundaries. 242 * This comes into play big time with port messages being in the 243 * same packet as register messages. Also, open receive channel 244 * acks are usually buried in a pakcet some 400 bytes long. 245 */ 246 while (dlen >= skinny_hdr_len) { 247 len = (sd->len); 248 msgId = (sd->msgId); 249 t = len; 250 251 if (t < 0 || t > orig_len || t > dlen) { 252 #ifdef DEBUG 253 fprintf(stderr, 254 "PacketAlias/Skinny: Not a skinny packet, invalid length \n"); 255 #endif 256 return; 257 } 258 switch (msgId) { 259 case REG_MSG: { 260 struct RegisterMessage *reg_mesg; 261 262 if (len < sizeof(struct RegisterMessage)) { 263 #ifdef DEBUG 264 fprintf(stderr, 265 "PacketAlias/Skinny: Not a skinny packet, bad registration message\n"); 266 #endif 267 return; 268 } 269 reg_mesg = (struct RegisterMessage *)&sd->msgId; 270 #ifdef DEBUG 271 fprintf(stderr, 272 "PacketAlias/Skinny: Received a register message"); 273 #endif 274 alias_skinny_reg_msg(reg_mesg, pip, tc, link, direction); 275 break; 276 } 277 case IP_PORT_MSG: { 278 struct IpPortMessage *port_mesg; 279 280 if (len < sizeof(struct IpPortMessage)) { 281 #ifdef DEBUG 282 fprintf(stderr, 283 "PacketAlias/Skinny: Not a skinny packet, port message\n"); 284 #endif 285 return; 286 } 287 #ifdef DEBUG 288 fprintf(stderr 289 "PacketAlias/Skinny: Received ipport message\n"); 290 #endif 291 port_mesg = (struct IpPortMessage *)&sd->msgId; 292 alias_skinny_port_msg(port_mesg, pip, tc, link, direction); 293 break; 294 } 295 case OPNRCVCH_ACK: { 296 struct OpenReceiveChannelAck *opnrcvchn_ack; 297 298 if (len < sizeof(struct OpenReceiveChannelAck)) { 299 #ifdef DEBUG 300 fprintf(stderr, 301 "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n"); 302 #endif 303 return; 304 } 305 #ifdef DEBUG 306 fprintf(stderr, 307 "PacketAlias/Skinny: Received open rcv channel msg\n"); 308 #endif 309 opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId; 310 alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, link, &lip, direction); 311 break; 312 } 313 case START_MEDIATX: { 314 struct StartMediaTransmission *startmedia_tx; 315 316 if (len < sizeof(struct StartMediaTransmission)) { 317 #ifdef DEBUG 318 fprintf(stderr, 319 "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n"); 320 #endif 321 return; 322 } 323 #ifdef DEBUG 324 fprintf(stderr, 325 "PacketAlias/Skinny: Received start media trans msg\n"); 326 #endif 327 startmedia_tx = (struct StartMediaTransmission *)&sd->msgId; 328 alias_skinny_startmedia(startmedia_tx, pip, tc, link, lip, direction); 329 break; 330 } 331 default: 332 break; 333 } 334 /* Place the pointer at the next message in the packet. */ 335 dlen -= len + (skinny_hdr_len - sizeof(msgId)); 336 sd = (struct skinny_header *)(((char *)&sd->msgId) + len); 337 } 338 } 339