1 | /*-
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2 | * alias_skinny.c
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3 | *
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4 | * Copyright (c) 2002, 2003 MarcusCom, Inc.
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5 | * All rights reserved.
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6 | *
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7 | * Redistribution and use in source and binary forms, with or without
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8 | * modification, are permitted provided that the following conditions
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9 | * are met:
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10 | * 1. Redistributions of source code must retain the above copyright
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11 | * notice, this list of conditions and the following disclaimer.
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12 | * 2. Redistributions in binary form must reproduce the above copyright
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13 | * notice, this list of conditions and the following disclaimer in the
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14 | * documentation and/or other materials provided with the distribution.
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15 | *
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16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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17 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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20 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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21 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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22 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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23 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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24 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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25 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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26 | * SUCH DAMAGE.
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27 | *
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28 | * Author: Joe Marcus Clarke <[email protected]>
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29 | *
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30 | * $FreeBSD: src/sys/netinet/libalias/alias_skinny.c,v 1.14.8.1 2009/04/15 03:14:26 kensmith Exp $
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31 | */
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32 |
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33 | #ifdef _KERNEL
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34 | #include <sys/param.h>
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35 | #include <sys/kernel.h>
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36 | #include <sys/module.h>
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37 | #else
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38 | #include <errno.h>
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39 | #include <stdio.h>
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40 | #include <unistd.h>
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41 | #endif
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42 |
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43 | #include <netinet/in_systm.h>
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44 | #include <netinet/in.h>
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45 | #include <netinet/ip.h>
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46 | #include <netinet/tcp.h>
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47 |
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48 | #ifdef _KERNEL
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49 | #include <netinet/libalias/alias_local.h>
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50 | #include <netinet/libalias/alias_mod.h>
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51 | #else
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52 | #include "alias_local.h"
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53 | #include "alias_mod.h"
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54 | #endif
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55 |
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56 | static void
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57 | AliasHandleSkinny(struct libalias *, struct ip *, struct alias_link *);
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58 |
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59 | static int
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60 | fingerprint(struct libalias *la, struct ip *pip, struct alias_data *ah)
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61 | {
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62 |
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63 | if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL)
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64 | return (-1);
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65 | if (la->skinnyPort != 0 && (ntohs(*ah->sport) == la->skinnyPort ||
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66 | ntohs(*ah->dport) == la->skinnyPort))
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67 | return (0);
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68 | return (-1);
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69 | }
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70 |
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71 | static int
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72 | protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah)
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73 | {
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74 |
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75 | AliasHandleSkinny(la, pip, ah->lnk);
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76 | return (0);
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77 | }
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78 |
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79 | struct proto_handler handlers[] = {
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80 | {
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81 | .pri = 110,
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82 | .dir = IN|OUT,
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83 | .proto = TCP,
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84 | .fingerprint = &fingerprint,
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85 | .protohandler = &protohandler
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86 | },
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87 | { EOH }
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88 | };
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89 |
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90 | static int
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91 | mod_handler(module_t mod, int type, void *data)
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92 | {
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93 | int error;
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94 |
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95 | switch (type) {
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96 | case MOD_LOAD:
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97 | error = 0;
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98 | LibAliasAttachHandlers(handlers);
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99 | break;
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100 | case MOD_UNLOAD:
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101 | error = 0;
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102 | LibAliasDetachHandlers(handlers);
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103 | break;
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104 | default:
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105 | error = EINVAL;
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106 | }
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107 | return (error);
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108 | }
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109 |
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110 | #ifdef _KERNEL
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111 | static
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112 | #endif
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113 | moduledata_t alias_mod = {
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114 | "alias_skinny", mod_handler, NULL
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115 | };
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116 |
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117 | #ifdef _KERNEL
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118 | DECLARE_MODULE(alias_skinny, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
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119 | MODULE_VERSION(alias_skinny, 1);
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120 | MODULE_DEPEND(alias_skinny, libalias, 1, 1, 1);
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121 | #endif
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122 |
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123 | /*
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124 | * alias_skinny.c handles the translation for the Cisco Skinny Station
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125 | * protocol. Skinny typically uses TCP port 2000 to set up calls between
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126 | * a Cisco Call Manager and a Cisco IP phone. When a phone comes on line,
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127 | * it first needs to register with the Call Manager. To do this it sends
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128 | * a registration message. This message contains the IP address of the
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129 | * IP phone. This message must then be translated to reflect our global
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130 | * IP address. Along with the registration message (and usually in the
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131 | * same packet), the phone sends an IP port message. This message indicates
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132 | * the TCP port over which it will communicate.
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133 | *
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134 | * When a call is placed from the phone, the Call Manager will send an
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135 | * Open Receive Channel message to the phone to let the caller know someone
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136 | * has answered. The phone then sends back an Open Receive Channel
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137 | * Acknowledgement. In this packet, the phone sends its IP address again,
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138 | * and the UDP port over which the voice traffic should flow. These values
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139 | * need translation. Right after the Open Receive Channel Acknowledgement,
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140 | * the Call Manager sends a Start Media Transmission message indicating the
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141 | * call is connected. This message contains the IP address and UDP port
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142 | * number of the remote (called) party. Once this message is translated, the
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143 | * call can commence. The called part sends the first UDP packet to the
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144 | * calling phone at the pre-arranged UDP port in the Open Receive Channel
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145 | * Acknowledgement.
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146 | *
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147 | * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems,
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148 | * Inc. All rights reserved.
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149 | */
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150 |
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151 | /* #define LIBALIAS_DEBUG 1 */
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152 |
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153 | /* Message types that need translating */
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154 | #define REG_MSG 0x00000001
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155 | #define IP_PORT_MSG 0x00000002
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156 | #define OPNRCVCH_ACK 0x00000022
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157 | #define START_MEDIATX 0x0000008a
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158 |
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159 | struct skinny_header {
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160 | u_int32_t len;
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161 | u_int32_t reserved;
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162 | u_int32_t msgId;
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163 | };
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164 |
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165 | struct RegisterMessage {
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166 | u_int32_t msgId;
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167 | char devName [16];
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168 | u_int32_t uid;
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169 | u_int32_t instance;
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170 | u_int32_t ipAddr;
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171 | u_char devType;
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172 | u_int32_t maxStreams;
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173 | };
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174 |
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175 | struct IpPortMessage {
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176 | u_int32_t msgId;
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177 | u_int32_t stationIpPort; /* Note: Skinny uses 32-bit port
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178 | * numbers */
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179 | };
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180 |
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181 | struct OpenReceiveChannelAck {
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182 | u_int32_t msgId;
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183 | u_int32_t status;
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184 | u_int32_t ipAddr;
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185 | u_int32_t port;
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186 | u_int32_t passThruPartyID;
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187 | };
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188 |
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189 | struct StartMediaTransmission {
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190 | u_int32_t msgId;
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191 | u_int32_t conferenceID;
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192 | u_int32_t passThruPartyID;
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193 | u_int32_t remoteIpAddr;
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194 | u_int32_t remotePort;
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195 | u_int32_t MSPacket;
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196 | u_int32_t payloadCap;
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197 | u_int32_t precedence;
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198 | u_int32_t silenceSuppression;
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199 | u_short maxFramesPerPacket;
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200 | u_int32_t G723BitRate;
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201 | };
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202 |
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203 | typedef enum {
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204 | ClientToServer = 0,
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205 | ServerToClient = 1
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206 | } ConvDirection;
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207 |
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208 |
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209 | static int
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210 | alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip,
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211 | struct tcphdr *tc, struct alias_link *lnk,
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212 | ConvDirection direction)
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213 | {
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214 | (void)direction;
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215 |
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216 | reg_msg->ipAddr = (u_int32_t) GetAliasAddress(lnk).s_addr;
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217 |
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218 | tc->th_sum = 0;
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219 | #ifdef _KERNEL
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220 | tc->th_x2 = 1;
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221 | #else
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222 | tc->th_sum = TcpChecksum(pip);
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223 | #endif
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224 |
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225 | return (0);
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226 | }
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227 |
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228 | static int
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229 | alias_skinny_startmedia(struct StartMediaTransmission *start_media,
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230 | struct ip *pip, struct tcphdr *tc,
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231 | struct alias_link *lnk, u_int32_t localIpAddr,
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232 | ConvDirection direction)
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233 | {
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234 | struct in_addr dst, src;
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235 |
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236 | (void)pip;
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237 | (void)tc;
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238 | (void)lnk;
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239 | (void)direction;
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240 |
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241 | dst.s_addr = start_media->remoteIpAddr;
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242 | src.s_addr = localIpAddr;
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243 |
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244 | /*
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245 | * XXX I should probably handle in bound global translations as
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246 | * well.
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247 | */
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248 |
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249 | return (0);
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250 | }
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251 |
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252 | static int
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253 | alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip,
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254 | struct tcphdr *tc, struct alias_link *lnk,
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255 | ConvDirection direction)
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256 | {
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257 | (void)direction;
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258 |
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259 | port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(lnk));
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260 |
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261 | tc->th_sum = 0;
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262 | #ifdef _KERNEL
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263 | tc->th_x2 = 1;
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264 | #else
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265 | tc->th_sum = TcpChecksum(pip);
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266 | #endif
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267 | return (0);
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268 | }
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269 |
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270 | static int
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271 | alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack,
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272 | struct ip *pip, struct tcphdr *tc,
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273 | struct alias_link *lnk, u_int32_t * localIpAddr,
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274 | ConvDirection direction)
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275 | {
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276 | struct in_addr null_addr;
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277 | struct alias_link *opnrcv_lnk;
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278 | u_int32_t localPort;
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279 |
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280 | (void)lnk;
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281 | (void)direction;
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282 |
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283 | *localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr;
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284 | localPort = opnrcvch_ack->port;
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285 |
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286 | null_addr.s_addr = INADDR_ANY;
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287 | opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr,
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288 | htons((u_short) opnrcvch_ack->port), 0,
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289 | IPPROTO_UDP, 1);
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290 | opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_lnk).s_addr;
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291 | opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_lnk));
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292 |
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293 | tc->th_sum = 0;
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294 | #ifdef _KERNEL
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295 | tc->th_x2 = 1;
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296 | #else
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297 | tc->th_sum = TcpChecksum(pip);
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298 | #endif
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299 | return (0);
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300 | }
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301 |
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302 | static void
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303 | AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk)
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304 | {
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305 | size_t hlen, tlen, dlen;
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306 | struct tcphdr *tc;
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307 | u_int32_t msgId, t, len, lip;
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308 | struct skinny_header *sd;
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309 | size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header);
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310 | ConvDirection direction;
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311 |
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312 | lip = -1;
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313 | tc = (struct tcphdr *)ip_next(pip);
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314 | hlen = (pip->ip_hl + tc->th_off) << 2;
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315 | tlen = ntohs(pip->ip_len);
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316 | dlen = tlen - hlen;
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317 |
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318 | sd = (struct skinny_header *)tcp_next(tc);
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319 |
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320 | /*
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321 | * XXX This direction is reserved for future use. I still need to
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322 | * handle the scenario where the call manager is on the inside, and
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323 | * the calling phone is on the global outside.
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324 | */
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325 | if (ntohs(tc->th_dport) == la->skinnyPort) {
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326 | direction = ClientToServer;
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327 | } else if (ntohs(tc->th_sport) == la->skinnyPort) {
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328 | direction = ServerToClient;
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329 | } else {
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330 | #ifdef LIBALIAS_DEBUG
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331 | fprintf(stderr,
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332 | "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n");
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333 | #endif
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334 | return;
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335 | }
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336 |
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337 | orig_len = dlen;
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338 | /*
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339 | * Skinny packets can contain many messages. We need to loop
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340 | * through the packet using len to determine message boundaries.
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341 | * This comes into play big time with port messages being in the
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342 | * same packet as register messages. Also, open receive channel
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343 | * acks are usually buried in a pakcet some 400 bytes long.
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344 | */
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345 | while (dlen >= skinny_hdr_len) {
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346 | len = (sd->len);
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347 | msgId = (sd->msgId);
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348 | t = len;
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349 |
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350 | if (t > orig_len || t > dlen) {
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351 | #ifdef LIBALIAS_DEBUG
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352 | fprintf(stderr,
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353 | "PacketAlias/Skinny: Not a skinny packet, invalid length \n");
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354 | #endif
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355 | return;
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356 | }
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357 | switch (msgId) {
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358 | case REG_MSG: {
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359 | struct RegisterMessage *reg_mesg;
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360 |
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361 | if (len < (int)sizeof(struct RegisterMessage)) {
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362 | #ifdef LIBALIAS_DEBUG
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363 | fprintf(stderr,
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364 | "PacketAlias/Skinny: Not a skinny packet, bad registration message\n");
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365 | #endif
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366 | return;
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367 | }
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368 | reg_mesg = (struct RegisterMessage *)&sd->msgId;
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369 | #ifdef LIBALIAS_DEBUG
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370 | fprintf(stderr,
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371 | "PacketAlias/Skinny: Received a register message");
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372 | #endif
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373 | alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction);
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374 | break;
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375 | }
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376 | case IP_PORT_MSG: {
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377 | struct IpPortMessage *port_mesg;
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378 |
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379 | if (len < (int)sizeof(struct IpPortMessage)) {
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380 | #ifdef LIBALIAS_DEBUG
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381 | fprintf(stderr,
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382 | "PacketAlias/Skinny: Not a skinny packet, port message\n");
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383 | #endif
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384 | return;
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385 | }
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386 | #ifdef LIBALIAS_DEBUG
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387 | fprintf(stderr,
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388 | "PacketAlias/Skinny: Received ipport message\n");
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389 | #endif
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390 | port_mesg = (struct IpPortMessage *)&sd->msgId;
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391 | alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction);
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392 | break;
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393 | }
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394 | case OPNRCVCH_ACK: {
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395 | struct OpenReceiveChannelAck *opnrcvchn_ack;
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396 |
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397 | if (len < (int)sizeof(struct OpenReceiveChannelAck)) {
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398 | #ifdef LIBALIAS_DEBUG
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399 | fprintf(stderr,
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400 | "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n");
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401 | #endif
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402 | return;
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403 | }
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404 | #ifdef LIBALIAS_DEBUG
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405 | fprintf(stderr,
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406 | "PacketAlias/Skinny: Received open rcv channel msg\n");
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407 | #endif
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408 | opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId;
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409 | alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction);
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410 | break;
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411 | }
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412 | case START_MEDIATX: {
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413 | struct StartMediaTransmission *startmedia_tx;
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414 |
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415 | if (len < (int)sizeof(struct StartMediaTransmission)) {
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416 | #ifdef LIBALIAS_DEBUG
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417 | fprintf(stderr,
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418 | "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n");
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419 | #endif
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420 | return;
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421 | }
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422 | if (lip == -1) {
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423 | #ifdef LIBALIAS_DEBUG
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424 | fprintf(stderr,
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425 | "PacketAlias/Skinny: received a"
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426 | " packet,StartMediaTx Message before"
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427 | " packet,OpnRcvChnAckMsg\n"
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428 | #endif
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429 | return;
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430 | }
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431 |
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432 | #ifdef LIBALIAS_DEBUG
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433 | fprintf(stderr,
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434 | "PacketAlias/Skinny: Received start media trans msg\n");
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435 | #endif
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436 | startmedia_tx = (struct StartMediaTransmission *)&sd->msgId;
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437 | alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction);
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438 | break;
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439 | }
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440 | default:
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441 | break;
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442 | }
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443 | /* Place the pointer at the next message in the packet. */
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444 | dlen -= len + (skinny_hdr_len - sizeof(msgId));
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445 | sd = (struct skinny_header *)(((char *)&sd->msgId) + len);
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446 | }
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447 | }
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