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 *lnk, 136 ConvDirection direction) 137 { 138 (void)direction; 139 140 reg_msg->ipAddr = (u_int32_t) GetAliasAddress(lnk).s_addr; 141 142 tc->th_sum = 0; 143 tc->th_sum = TcpChecksum(pip); 144 145 return (0); 146 } 147 148 static int 149 alias_skinny_startmedia(struct StartMediaTransmission *start_media, 150 struct ip *pip, struct tcphdr *tc, 151 struct alias_link *lnk, u_int32_t localIpAddr, 152 ConvDirection direction) 153 { 154 struct in_addr dst, src; 155 156 (void)pip; 157 (void)tc; 158 (void)lnk; 159 (void)direction; 160 161 dst.s_addr = start_media->remoteIpAddr; 162 src.s_addr = localIpAddr; 163 164 /* 165 * XXX I should probably handle in bound global translations as 166 * well. 167 */ 168 169 return (0); 170 } 171 172 static int 173 alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip, 174 struct tcphdr *tc, struct alias_link *lnk, 175 ConvDirection direction) 176 { 177 (void)direction; 178 179 port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(lnk)); 180 181 tc->th_sum = 0; 182 tc->th_sum = TcpChecksum(pip); 183 184 return (0); 185 } 186 187 static int 188 alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack, 189 struct ip *pip, struct tcphdr *tc, 190 struct alias_link *lnk, u_int32_t * localIpAddr, 191 ConvDirection direction) 192 { 193 struct in_addr null_addr; 194 struct alias_link *opnrcv_lnk; 195 u_int32_t localPort; 196 197 (void)lnk; 198 (void)direction; 199 200 *localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr; 201 localPort = opnrcvch_ack->port; 202 203 null_addr.s_addr = INADDR_ANY; 204 opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr, 205 htons((u_short) opnrcvch_ack->port), 0, 206 IPPROTO_UDP, 1); 207 opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_lnk).s_addr; 208 opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_lnk)); 209 210 tc->th_sum = 0; 211 tc->th_sum = TcpChecksum(pip); 212 213 return (0); 214 } 215 216 void 217 AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk) 218 { 219 int hlen, tlen, dlen; 220 struct tcphdr *tc; 221 int32_t msgId, len, t, lip; 222 struct skinny_header *sd; 223 int orig_len, skinny_hdr_len = sizeof(struct skinny_header); 224 ConvDirection direction; 225 226 tc = (struct tcphdr *)ip_next(pip); 227 hlen = (pip->ip_hl + tc->th_off) << 2; 228 tlen = ntohs(pip->ip_len); 229 dlen = tlen - hlen; 230 231 sd = (struct skinny_header *)ip_next(pip); 232 233 /* 234 * XXX This direction is reserved for future use. I still need to 235 * handle the scenario where the call manager is on the inside, and 236 * the calling phone is on the global outside. 237 */ 238 if (ntohs(tc->th_dport) == la->skinnyPort) { 239 direction = ClientToServer; 240 } else if (ntohs(tc->th_sport) == la->skinnyPort) { 241 direction = ServerToClient; 242 } else { 243 #ifdef DEBUG 244 fprintf(stderr, 245 "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n"); 246 #endif 247 return; 248 } 249 250 orig_len = dlen; 251 /* 252 * Skinny packets can contain many messages. We need to loop 253 * through the packet using len to determine message boundaries. 254 * This comes into play big time with port messages being in the 255 * same packet as register messages. Also, open receive channel 256 * acks are usually buried in a pakcet some 400 bytes long. 257 */ 258 while (dlen >= skinny_hdr_len) { 259 len = (sd->len); 260 msgId = (sd->msgId); 261 t = len; 262 263 if (t > orig_len || t > dlen) { 264 #ifdef DEBUG 265 fprintf(stderr, 266 "PacketAlias/Skinny: Not a skinny packet, invalid length \n"); 267 #endif 268 return; 269 } 270 switch (msgId) { 271 case REG_MSG: { 272 struct RegisterMessage *reg_mesg; 273 274 if (len < (int)sizeof(struct RegisterMessage)) { 275 #ifdef DEBUG 276 fprintf(stderr, 277 "PacketAlias/Skinny: Not a skinny packet, bad registration message\n"); 278 #endif 279 return; 280 } 281 reg_mesg = (struct RegisterMessage *)&sd->msgId; 282 #ifdef DEBUG 283 fprintf(stderr, 284 "PacketAlias/Skinny: Received a register message"); 285 #endif 286 alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction); 287 break; 288 } 289 case IP_PORT_MSG: { 290 struct IpPortMessage *port_mesg; 291 292 if (len < (int)sizeof(struct IpPortMessage)) { 293 #ifdef DEBUG 294 fprintf(stderr, 295 "PacketAlias/Skinny: Not a skinny packet, port message\n"); 296 #endif 297 return; 298 } 299 #ifdef DEBUG 300 fprintf(stderr 301 "PacketAlias/Skinny: Received ipport message\n"); 302 #endif 303 port_mesg = (struct IpPortMessage *)&sd->msgId; 304 alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction); 305 break; 306 } 307 case OPNRCVCH_ACK: { 308 struct OpenReceiveChannelAck *opnrcvchn_ack; 309 310 if (len < (int)sizeof(struct OpenReceiveChannelAck)) { 311 #ifdef DEBUG 312 fprintf(stderr, 313 "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n"); 314 #endif 315 return; 316 } 317 #ifdef DEBUG 318 fprintf(stderr, 319 "PacketAlias/Skinny: Received open rcv channel msg\n"); 320 #endif 321 opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId; 322 alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction); 323 break; 324 } 325 case START_MEDIATX: { 326 struct StartMediaTransmission *startmedia_tx; 327 328 if (len < (int)sizeof(struct StartMediaTransmission)) { 329 #ifdef DEBUG 330 fprintf(stderr, 331 "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n"); 332 #endif 333 return; 334 } 335 #ifdef DEBUG 336 fprintf(stderr, 337 "PacketAlias/Skinny: Received start media trans msg\n"); 338 #endif 339 startmedia_tx = (struct StartMediaTransmission *)&sd->msgId; 340 alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction); 341 break; 342 } 343 default: 344 break; 345 } 346 /* Place the pointer at the next message in the packet. */ 347 dlen -= len + (skinny_hdr_len - sizeof(msgId)); 348 sd = (struct skinny_header *)(((char *)&sd->msgId) + len); 349 } 350 } 351