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