/*- * alias_skinny.c * * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2002, 2003 MarcusCom, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * Author: Joe Marcus Clarke */ #ifdef _KERNEL #include #include #include #else #include #include #include #endif #include #include #include #include #ifdef _KERNEL #include #include #else #include "alias_local.h" #include "alias_mod.h" #endif static void AliasHandleSkinny(struct libalias *, struct ip *, struct alias_link *); static int fingerprint(struct libalias *la, struct alias_data *ah) { if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL) return (-1); if (la->skinnyPort != 0 && (ntohs(*ah->sport) == la->skinnyPort || ntohs(*ah->dport) == la->skinnyPort)) return (0); return (-1); } static int protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah) { AliasHandleSkinny(la, pip, ah->lnk); return (0); } struct proto_handler handlers[] = { { .pri = 110, .dir = IN|OUT, .proto = TCP, .fingerprint = &fingerprint, .protohandler = &protohandler }, { EOH } }; static int mod_handler(module_t mod, int type, void *data) { int error; switch (type) { case MOD_LOAD: error = 0; LibAliasAttachHandlers(handlers); break; case MOD_UNLOAD: error = 0; LibAliasDetachHandlers(handlers); break; default: error = EINVAL; } return (error); } #ifdef _KERNEL static #endif moduledata_t alias_mod = { "alias_skinny", mod_handler, NULL }; #ifdef _KERNEL DECLARE_MODULE(alias_skinny, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND); MODULE_VERSION(alias_skinny, 1); MODULE_DEPEND(alias_skinny, libalias, 1, 1, 1); #endif /* * alias_skinny.c handles the translation for the Cisco Skinny Station * protocol. Skinny typically uses TCP port 2000 to set up calls between * a Cisco Call Manager and a Cisco IP phone. When a phone comes on line, * it first needs to register with the Call Manager. To do this it sends * a registration message. This message contains the IP address of the * IP phone. This message must then be translated to reflect our global * IP address. Along with the registration message (and usually in the * same packet), the phone sends an IP port message. This message indicates * the TCP port over which it will communicate. * * When a call is placed from the phone, the Call Manager will send an * Open Receive Channel message to the phone to let the caller know someone * has answered. The phone then sends back an Open Receive Channel * Acknowledgement. In this packet, the phone sends its IP address again, * and the UDP port over which the voice traffic should flow. These values * need translation. Right after the Open Receive Channel Acknowledgement, * the Call Manager sends a Start Media Transmission message indicating the * call is connected. This message contains the IP address and UDP port * number of the remote (called) party. Once this message is translated, the * call can commence. The called part sends the first UDP packet to the * calling phone at the pre-arranged UDP port in the Open Receive Channel * Acknowledgement. * * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems, * Inc. All rights reserved. */ /* #define LIBALIAS_DEBUG 1 */ /* Message types that need translating */ #define REG_MSG 0x00000001 #define IP_PORT_MSG 0x00000002 #define OPNRCVCH_ACK 0x00000022 #define START_MEDIATX 0x0000008a struct skinny_header { u_int32_t len; u_int32_t reserved; u_int32_t msgId; }; struct RegisterMessage { u_int32_t msgId; char devName [16]; u_int32_t uid; u_int32_t instance; u_int32_t ipAddr; u_char devType; u_int32_t maxStreams; }; struct IpPortMessage { u_int32_t msgId; u_int32_t stationIpPort; /* Note: Skinny uses 32-bit port * numbers */ }; struct OpenReceiveChannelAck { u_int32_t msgId; u_int32_t status; u_int32_t ipAddr; u_int32_t port; u_int32_t passThruPartyID; }; struct StartMediaTransmission { u_int32_t msgId; u_int32_t conferenceID; u_int32_t passThruPartyID; u_int32_t remoteIpAddr; u_int32_t remotePort; u_int32_t MSPacket; u_int32_t payloadCap; u_int32_t precedence; u_int32_t silenceSuppression; u_short maxFramesPerPacket; u_int32_t G723BitRate; }; typedef enum { ClientToServer = 0, ServerToClient = 1 } ConvDirection; static int alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip, struct tcphdr *tc, struct alias_link *lnk, ConvDirection direction) { (void)direction; reg_msg->ipAddr = (u_int32_t)GetAliasAddress(lnk).s_addr; tc->th_sum = 0; #ifdef _KERNEL tc->th_x2 = (TH_RES1 >> 8); #else tc->th_sum = TcpChecksum(pip); #endif return (0); } static int alias_skinny_startmedia(struct StartMediaTransmission *start_media, struct ip *pip, struct tcphdr *tc, struct alias_link *lnk, u_int32_t localIpAddr, ConvDirection direction) { struct in_addr dst __unused, src __unused; (void)pip; (void)tc; (void)lnk; (void)direction; dst.s_addr = start_media->remoteIpAddr; src.s_addr = localIpAddr; /* * XXX I should probably handle in bound global translations as * well. */ return (0); } static int alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip, struct tcphdr *tc, struct alias_link *lnk, ConvDirection direction) { (void)direction; port_msg->stationIpPort = (u_int32_t)ntohs(GetAliasPort(lnk)); tc->th_sum = 0; #ifdef _KERNEL tc->th_x2 = (TH_RES1 >> 8); #else tc->th_sum = TcpChecksum(pip); #endif return (0); } static int alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack, struct ip *pip, struct tcphdr *tc, struct alias_link *lnk, u_int32_t * localIpAddr, ConvDirection direction) { struct in_addr null_addr; struct alias_link *opnrcv_lnk; (void)lnk; (void)direction; *localIpAddr = (u_int32_t)opnrcvch_ack->ipAddr; null_addr.s_addr = INADDR_ANY; opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr, htons((u_short) opnrcvch_ack->port), 0, IPPROTO_UDP, 1); opnrcvch_ack->ipAddr = (u_int32_t)GetAliasAddress(opnrcv_lnk).s_addr; opnrcvch_ack->port = (u_int32_t)ntohs(GetAliasPort(opnrcv_lnk)); tc->th_sum = 0; #ifdef _KERNEL tc->th_x2 = (TH_RES1 >> 8); #else tc->th_sum = TcpChecksum(pip); #endif return (0); } static void AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk) { size_t hlen, tlen, dlen; struct tcphdr *tc; u_int32_t msgId, t, len, lip; struct skinny_header *sd; size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header); ConvDirection direction; lip = -1; tc = (struct tcphdr *)ip_next(pip); hlen = (pip->ip_hl + tc->th_off) << 2; tlen = ntohs(pip->ip_len); dlen = tlen - hlen; sd = (struct skinny_header *)tcp_next(tc); /* * XXX This direction is reserved for future use. I still need to * handle the scenario where the call manager is on the inside, and * the calling phone is on the global outside. */ if (ntohs(tc->th_dport) == la->skinnyPort) direction = ClientToServer; else if (ntohs(tc->th_sport) == la->skinnyPort) direction = ServerToClient; else { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n"); #endif return; } orig_len = dlen; /* * Skinny packets can contain many messages. We need to loop * through the packet using len to determine message boundaries. * This comes into play big time with port messages being in the * same packet as register messages. Also, open receive channel * acks are usually buried in a packet some 400 bytes long. */ while (dlen >= skinny_hdr_len) { len = (sd->len); msgId = (sd->msgId); t = len; if (t > orig_len || t > dlen) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Not a skinny packet, invalid length \n"); #endif return; } switch (msgId) { case REG_MSG: { struct RegisterMessage *reg_mesg; if (len < (int)sizeof(struct RegisterMessage)) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Not a skinny packet, bad registration message\n"); #endif return; } reg_mesg = (struct RegisterMessage *)&sd->msgId; #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Received a register message"); #endif alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction); break; } case IP_PORT_MSG: { struct IpPortMessage *port_mesg; if (len < (int)sizeof(struct IpPortMessage)) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Not a skinny packet, port message\n"); #endif return; } #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Received ipport message\n"); #endif port_mesg = (struct IpPortMessage *)&sd->msgId; alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction); break; } case OPNRCVCH_ACK: { struct OpenReceiveChannelAck *opnrcvchn_ack; if (len < (int)sizeof(struct OpenReceiveChannelAck)) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n"); #endif return; } #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Received open rcv channel msg\n"); #endif opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId; alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction); break; } case START_MEDIATX: { struct StartMediaTransmission *startmedia_tx; if (len < (int)sizeof(struct StartMediaTransmission)) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n"); #endif return; } if (lip == -1) { #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: received a" " packet,StartMediaTx Message before" " packet,OpnRcvChnAckMsg\n" #endif return; } #ifdef LIBALIAS_DEBUG fprintf(stderr, "PacketAlias/Skinny: Received start media trans msg\n"); #endif startmedia_tx = (struct StartMediaTransmission *)&sd->msgId; alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction); break; } default: break; } /* Place the pointer at the next message in the packet. */ dlen -= len + (skinny_hdr_len - sizeof(msgId)); sd = (struct skinny_header *)(((char *)&sd->msgId) + len); } }