FreeBSD-5.3/lib/libalias/alias_skinny.c
/*-
* alias_skinny.c
*
* 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 <marcus@FreeBSD.org>
*
* $FreeBSD: src/lib/libalias/alias_skinny.c,v 1.7 2004/08/04 15:17:08 marcus Exp $
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <unistd.h>
#include "alias_local.h"
/*
* 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 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;
tc->th_sum = TcpChecksum(pip);
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, src;
(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;
tc->th_sum = TcpChecksum(pip);
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;
u_int32_t localPort;
(void)lnk;
(void)direction;
*localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr;
localPort = opnrcvch_ack->port;
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;
tc->th_sum = TcpChecksum(pip);
return (0);
}
void
AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk)
{
int hlen, tlen, dlen;
struct tcphdr *tc;
int32_t msgId, len, t, lip;
struct skinny_header *sd;
int orig_len, skinny_hdr_len = sizeof(struct skinny_header);
ConvDirection direction;
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 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 pakcet some 400 bytes long.
*/
while (dlen >= skinny_hdr_len) {
len = (sd->len);
msgId = (sd->msgId);
t = len;
if (t > orig_len || t > dlen) {
#ifdef 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 DEBUG
fprintf(stderr,
"PacketAlias/Skinny: Not a skinny packet, bad registration message\n");
#endif
return;
}
reg_mesg = (struct RegisterMessage *)&sd->msgId;
#ifdef 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 DEBUG
fprintf(stderr,
"PacketAlias/Skinny: Not a skinny packet, port message\n");
#endif
return;
}
#ifdef 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 DEBUG
fprintf(stderr,
"PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n");
#endif
return;
}
#ifdef 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 DEBUG
fprintf(stderr,
"PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n");
#endif
return;
}
#ifdef 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);
}
}