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 #ifdef _KERNEL 34 #include <sys/param.h> 35 #include <sys/kernel.h> 36 #include <sys/module.h> 37 #else 38 #include <errno.h> 39 #include <stdio.h> 40 #include <unistd.h> 41 #endif 42 43 #include <netinet/in_systm.h> 44 #include <netinet/in.h> 45 #include <netinet/ip.h> 46 #include <netinet/tcp.h> 47 48 #ifdef _KERNEL 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 static void 57 AliasHandleSkinny(struct libalias *, struct ip *, struct alias_link *); 58 59 static int 60 fingerprint(struct libalias *la, struct alias_data *ah) 61 { 62 63 if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL) 64 return (-1); 65 if (la->skinnyPort != 0 && (ntohs(*ah->sport) == la->skinnyPort || 66 ntohs(*ah->dport) == la->skinnyPort)) 67 return (0); 68 return (-1); 69 } 70 71 static int 72 protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah) 73 { 74 75 AliasHandleSkinny(la, pip, ah->lnk); 76 return (0); 77 } 78 79 struct proto_handler handlers[] = { 80 { 81 .pri = 110, 82 .dir = IN|OUT, 83 .proto = TCP, 84 .fingerprint = &fingerprint, 85 .protohandler = &protohandler 86 }, 87 { EOH } 88 }; 89 90 static int 91 mod_handler(module_t mod, int type, void *data) 92 { 93 int error; 94 95 switch (type) { 96 case MOD_LOAD: 97 error = 0; 98 LibAliasAttachHandlers(handlers); 99 break; 100 case MOD_UNLOAD: 101 error = 0; 102 LibAliasDetachHandlers(handlers); 103 break; 104 default: 105 error = EINVAL; 106 } 107 return (error); 108 } 109 110 #ifdef _KERNEL 111 static 112 #endif 113 moduledata_t alias_mod = { 114 "alias_skinny", mod_handler, NULL 115 }; 116 117 #ifdef _KERNEL 118 DECLARE_MODULE(alias_skinny, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND); 119 MODULE_VERSION(alias_skinny, 1); 120 MODULE_DEPEND(alias_skinny, libalias, 1, 1, 1); 121 #endif 122 123 /* 124 * alias_skinny.c handles the translation for the Cisco Skinny Station 125 * protocol. Skinny typically uses TCP port 2000 to set up calls between 126 * a Cisco Call Manager and a Cisco IP phone. When a phone comes on line, 127 * it first needs to register with the Call Manager. To do this it sends 128 * a registration message. This message contains the IP address of the 129 * IP phone. This message must then be translated to reflect our global 130 * IP address. Along with the registration message (and usually in the 131 * same packet), the phone sends an IP port message. This message indicates 132 * the TCP port over which it will communicate. 133 * 134 * When a call is placed from the phone, the Call Manager will send an 135 * Open Receive Channel message to the phone to let the caller know someone 136 * has answered. The phone then sends back an Open Receive Channel 137 * Acknowledgement. In this packet, the phone sends its IP address again, 138 * and the UDP port over which the voice traffic should flow. These values 139 * need translation. Right after the Open Receive Channel Acknowledgement, 140 * the Call Manager sends a Start Media Transmission message indicating the 141 * call is connected. This message contains the IP address and UDP port 142 * number of the remote (called) party. Once this message is translated, the 143 * call can commence. The called part sends the first UDP packet to the 144 * calling phone at the pre-arranged UDP port in the Open Receive Channel 145 * Acknowledgement. 146 * 147 * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems, 148 * Inc. All rights reserved. 149 */ 150 151 /* #define LIBALIAS_DEBUG 1 */ 152 153 /* Message types that need translating */ 154 #define REG_MSG 0x00000001 155 #define IP_PORT_MSG 0x00000002 156 #define OPNRCVCH_ACK 0x00000022 157 #define START_MEDIATX 0x0000008a 158 159 struct skinny_header { 160 u_int32_t len; 161 u_int32_t reserved; 162 u_int32_t msgId; 163 }; 164 165 struct RegisterMessage { 166 u_int32_t msgId; 167 char devName [16]; 168 u_int32_t uid; 169 u_int32_t instance; 170 u_int32_t ipAddr; 171 u_char devType; 172 u_int32_t maxStreams; 173 }; 174 175 struct IpPortMessage { 176 u_int32_t msgId; 177 u_int32_t stationIpPort; /* Note: Skinny uses 32-bit port 178 * numbers */ 179 }; 180 181 struct OpenReceiveChannelAck { 182 u_int32_t msgId; 183 u_int32_t status; 184 u_int32_t ipAddr; 185 u_int32_t port; 186 u_int32_t passThruPartyID; 187 }; 188 189 struct StartMediaTransmission { 190 u_int32_t msgId; 191 u_int32_t conferenceID; 192 u_int32_t passThruPartyID; 193 u_int32_t remoteIpAddr; 194 u_int32_t remotePort; 195 u_int32_t MSPacket; 196 u_int32_t payloadCap; 197 u_int32_t precedence; 198 u_int32_t silenceSuppression; 199 u_short maxFramesPerPacket; 200 u_int32_t G723BitRate; 201 }; 202 203 typedef enum { 204 ClientToServer = 0, 205 ServerToClient = 1 206 } ConvDirection; 207 208 209 static int 210 alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip, 211 struct tcphdr *tc, struct alias_link *lnk, 212 ConvDirection direction) 213 { 214 (void)direction; 215 216 reg_msg->ipAddr = (u_int32_t) GetAliasAddress(lnk).s_addr; 217 218 tc->th_sum = 0; 219 #ifdef _KERNEL 220 tc->th_x2 = 1; 221 #else 222 tc->th_sum = TcpChecksum(pip); 223 #endif 224 225 return (0); 226 } 227 228 static int 229 alias_skinny_startmedia(struct StartMediaTransmission *start_media, 230 struct ip *pip, struct tcphdr *tc, 231 struct alias_link *lnk, u_int32_t localIpAddr, 232 ConvDirection direction) 233 { 234 struct in_addr dst, src; 235 236 (void)pip; 237 (void)tc; 238 (void)lnk; 239 (void)direction; 240 241 dst.s_addr = start_media->remoteIpAddr; 242 src.s_addr = localIpAddr; 243 244 /* 245 * XXX I should probably handle in bound global translations as 246 * well. 247 */ 248 249 return (0); 250 } 251 252 static int 253 alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip, 254 struct tcphdr *tc, struct alias_link *lnk, 255 ConvDirection direction) 256 { 257 (void)direction; 258 259 port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(lnk)); 260 261 tc->th_sum = 0; 262 #ifdef _KERNEL 263 tc->th_x2 = 1; 264 #else 265 tc->th_sum = TcpChecksum(pip); 266 #endif 267 return (0); 268 } 269 270 static int 271 alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack, 272 struct ip *pip, struct tcphdr *tc, 273 struct alias_link *lnk, u_int32_t * localIpAddr, 274 ConvDirection direction) 275 { 276 struct in_addr null_addr; 277 struct alias_link *opnrcv_lnk; 278 u_int32_t localPort; 279 280 (void)lnk; 281 (void)direction; 282 283 *localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr; 284 localPort = opnrcvch_ack->port; 285 286 null_addr.s_addr = INADDR_ANY; 287 opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr, 288 htons((u_short) opnrcvch_ack->port), 0, 289 IPPROTO_UDP, 1); 290 opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_lnk).s_addr; 291 opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_lnk)); 292 293 tc->th_sum = 0; 294 #ifdef _KERNEL 295 tc->th_x2 = 1; 296 #else 297 tc->th_sum = TcpChecksum(pip); 298 #endif 299 return (0); 300 } 301 302 static void 303 AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk) 304 { 305 size_t hlen, tlen, dlen; 306 struct tcphdr *tc; 307 u_int32_t msgId, t, len, lip; 308 struct skinny_header *sd; 309 size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header); 310 ConvDirection direction; 311 312 lip = -1; 313 tc = (struct tcphdr *)ip_next(pip); 314 hlen = (pip->ip_hl + tc->th_off) << 2; 315 tlen = ntohs(pip->ip_len); 316 dlen = tlen - hlen; 317 318 sd = (struct skinny_header *)tcp_next(tc); 319 320 /* 321 * XXX This direction is reserved for future use. I still need to 322 * handle the scenario where the call manager is on the inside, and 323 * the calling phone is on the global outside. 324 */ 325 if (ntohs(tc->th_dport) == la->skinnyPort) { 326 direction = ClientToServer; 327 } else if (ntohs(tc->th_sport) == la->skinnyPort) { 328 direction = ServerToClient; 329 } else { 330 #ifdef LIBALIAS_DEBUG 331 fprintf(stderr, 332 "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n"); 333 #endif 334 return; 335 } 336 337 orig_len = dlen; 338 /* 339 * Skinny packets can contain many messages. We need to loop 340 * through the packet using len to determine message boundaries. 341 * This comes into play big time with port messages being in the 342 * same packet as register messages. Also, open receive channel 343 * acks are usually buried in a pakcet some 400 bytes long. 344 */ 345 while (dlen >= skinny_hdr_len) { 346 len = (sd->len); 347 msgId = (sd->msgId); 348 t = len; 349 350 if (t > orig_len || t > dlen) { 351 #ifdef LIBALIAS_DEBUG 352 fprintf(stderr, 353 "PacketAlias/Skinny: Not a skinny packet, invalid length \n"); 354 #endif 355 return; 356 } 357 switch (msgId) { 358 case REG_MSG: { 359 struct RegisterMessage *reg_mesg; 360 361 if (len < (int)sizeof(struct RegisterMessage)) { 362 #ifdef LIBALIAS_DEBUG 363 fprintf(stderr, 364 "PacketAlias/Skinny: Not a skinny packet, bad registration message\n"); 365 #endif 366 return; 367 } 368 reg_mesg = (struct RegisterMessage *)&sd->msgId; 369 #ifdef LIBALIAS_DEBUG 370 fprintf(stderr, 371 "PacketAlias/Skinny: Received a register message"); 372 #endif 373 alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction); 374 break; 375 } 376 case IP_PORT_MSG: { 377 struct IpPortMessage *port_mesg; 378 379 if (len < (int)sizeof(struct IpPortMessage)) { 380 #ifdef LIBALIAS_DEBUG 381 fprintf(stderr, 382 "PacketAlias/Skinny: Not a skinny packet, port message\n"); 383 #endif 384 return; 385 } 386 #ifdef LIBALIAS_DEBUG 387 fprintf(stderr, 388 "PacketAlias/Skinny: Received ipport message\n"); 389 #endif 390 port_mesg = (struct IpPortMessage *)&sd->msgId; 391 alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction); 392 break; 393 } 394 case OPNRCVCH_ACK: { 395 struct OpenReceiveChannelAck *opnrcvchn_ack; 396 397 if (len < (int)sizeof(struct OpenReceiveChannelAck)) { 398 #ifdef LIBALIAS_DEBUG 399 fprintf(stderr, 400 "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n"); 401 #endif 402 return; 403 } 404 #ifdef LIBALIAS_DEBUG 405 fprintf(stderr, 406 "PacketAlias/Skinny: Received open rcv channel msg\n"); 407 #endif 408 opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId; 409 alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction); 410 break; 411 } 412 case START_MEDIATX: { 413 struct StartMediaTransmission *startmedia_tx; 414 415 if (len < (int)sizeof(struct StartMediaTransmission)) { 416 #ifdef LIBALIAS_DEBUG 417 fprintf(stderr, 418 "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n"); 419 #endif 420 return; 421 } 422 if (lip == -1) { 423 #ifdef LIBALIAS_DEBUG 424 fprintf(stderr, 425 "PacketAlias/Skinny: received a" 426 " packet,StartMediaTx Message before" 427 " packet,OpnRcvChnAckMsg\n" 428 #endif 429 return; 430 } 431 432 #ifdef LIBALIAS_DEBUG 433 fprintf(stderr, 434 "PacketAlias/Skinny: Received start media trans msg\n"); 435 #endif 436 startmedia_tx = (struct StartMediaTransmission *)&sd->msgId; 437 alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction); 438 break; 439 } 440 default: 441 break; 442 } 443 /* Place the pointer at the next message in the packet. */ 444 dlen -= len + (skinny_hdr_len - sizeof(msgId)); 445 sd = (struct skinny_header *)(((char *)&sd->msgId) + len); 446 } 447 } 448