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1 // Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies). |
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2 // All rights reserved. |
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3 // This component and the accompanying materials are made available |
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4 // under the terms of the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members |
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5 // which accompanies this distribution, and is available |
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6 // at the URL "http://www.symbianfoundation.org/legal/licencesv10.html". |
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7 // |
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8 // Initial Contributors: |
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9 // Nokia Corporation - initial contribution. |
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10 // |
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11 // Contributors: |
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12 // |
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13 // Description: |
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14 // ip6_hdr.h - IPv6 header structure |
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15 // This module defines the basic classes for accessing the header |
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16 // structures within IPv6 packets. |
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17 // Defines the IPv6 header structure. |
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18 // |
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19 |
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20 |
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21 |
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22 /** |
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23 @file ip6_hdr.h |
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24 @ingroup ip_packet_formats |
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25 @publishedAll |
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26 @released |
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27 */ |
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28 |
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29 #ifndef __IP6_HDR_H__ |
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30 #define __IP6_HDR_H__ |
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31 |
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32 #include "in_hdr.h" |
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33 #include <in_sock.h> // Only for TIp6Addr ! |
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34 |
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35 /** |
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36 * @defgroup ip_packet_formats IPv4 and IPv6 packet formats and constants |
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37 * |
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38 * These headers define various constants and special <em>mapping or overlay |
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39 * classes</em> to be used in accessing and building the IP packets. The |
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40 * mapping classes are not intended to be used in declaring |
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41 * variables (although some of them do support that use also). |
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42 * |
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43 * The normal usage is to typecast a binary buffer |
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44 * to a mapping class. For example |
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45 * assuming a buf contains a raw IPv6 packet: |
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46 * |
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47 @code |
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48 TBuf8<2000> buf; |
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49 |
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50 TInet6HeaderIP &ip = *(TInet6HeaderIP *)buf.Ptr(); |
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51 if (ip.MinHeaderLength() > buf.Length() || |
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52 ip.HeaderLength() + ip.PayloadLength() > buf.Length()) |
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53 { |
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54 // Oops. packet too short! |
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55 } |
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56 else if (ip.Version() == 6) |
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57 { |
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58 // Packet seems to be IPv6 packet. |
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59 } |
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60 @endcode |
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61 * |
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62 * Within the TCP/IP stack, the packets are stored in RMBufChain objects. |
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63 * The data is not in a contiguous memory area and accessing the headers is |
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64 * more complicated. For that purpose there is a template class TInet6Packet, |
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65 * which can use any <em>mapping class</em> as a template parameter and |
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66 * provides functions to access the header within the chain. Assuming the |
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67 * a RMBufChain object buf contains the packet, equivalent code would be: |
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68 * |
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69 @code |
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70 RMBufChain buf; |
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71 |
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72 TInet6Packet<TInet6HeaderIP> ip(buf); |
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73 if (ip.iHdr == NULL || |
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74 ip.iHdr->HeaderLength() + ip.iHdr->PayloadLength() > buf.Length()) |
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75 { |
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76 // Opps. packet too short! |
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77 } |
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78 else if (ip.iHdr->Version() == 6) |
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79 { |
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80 // Packet seems to be IPv6 packet. |
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81 } |
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82 @endcode |
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83 * The TInet6Packet template does automatic MinHeaderLength check. The iHdr |
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84 * member variable is set only if the mapping succeeds at least for MinHeaderLength |
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85 * octets. |
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86 * |
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87 * All mapping headers must have the following functions defined: |
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88 * |
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89 * - static function MinHeaderLength returns the minimum header length in octets. |
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90 * |
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91 * - static function MaxHeaderLength returns the maximum header length in octets (not used much). |
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92 * |
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93 * - HeaderLength returns the actual length of a header instance in octets. |
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94 * Note that this may return garbage value, if the mapped header is invalid. |
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95 * The return value can be larger than indicated by MinHeaderLength, and |
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96 * as the mapping is only guaranteed up to that size, user must separately |
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97 * verify the accessibility of a full header in such case. |
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98 * @{ |
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99 * @} |
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100 */ |
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101 |
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102 /** |
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103 * @addtogroup ip_packet_formats |
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104 * @{ |
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105 */ |
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106 |
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107 /** |
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108 * The IPv6 minimum value for Maximum Transmission Unit (MTU) as defined in RFC 2460. |
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109 * |
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110 * @since v7.0 |
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111 */ |
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112 const TInt KInet6MinMtu = 1280; |
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113 |
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114 // |
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115 // TInet6HeaderIP |
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116 // ************** |
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117 // Methods of manipulating IPv6 IP header. |
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118 // |
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119 // This implementation assumes TUint8 is exactly 8 bits (and not |
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120 // 9 or more) |
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121 class TInet6HeaderIP |
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122 /** |
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123 * Encapsulates an IPv6 IP header. |
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124 * @verbatim |
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125 ************************* |
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126 Extract from the RFC-2460 |
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127 ************************* |
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128 |
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129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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130 |Version| Traffic Class | Flow Label | |
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131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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132 | Payload Length | Next Header | Hop Limit | |
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133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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134 | | |
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135 + + |
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136 | | |
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137 + Source Address + |
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138 | | |
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139 + + |
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140 | | |
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141 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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142 | | |
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143 + + |
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144 | | |
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145 + Destination Address + |
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146 | | |
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147 + + |
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148 | | |
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149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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150 |
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151 Version 4-bit Internet Protocol version number = 6. |
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152 |
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153 Traffic Class 8-bit traffic class field. See section 7. |
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154 |
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155 Flow Label 20-bit flow label. See section 6. |
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156 |
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157 Payload Length 16-bit unsigned integer. Length of the IPv6 |
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158 payload, i.e., the rest of the packet following |
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159 this IPv6 header, in octets. (Note that any |
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160 extension headers [section 4] present are |
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161 considered part of the payload, i.e., included |
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162 in the length count.) |
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163 |
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164 Next Header 8-bit selector. Identifies the type of header |
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165 immediately following the IPv6 header. Uses the |
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166 same values as the IPv4 Protocol field [RFC-1700 |
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167 et seq.]. |
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168 |
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169 Hop Limit 8-bit unsigned integer. Decremented by 1 by |
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170 each node that forwards the packet. The packet |
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171 is discarded if Hop Limit is decremented to |
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172 zero. |
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173 |
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174 Source Address 128-bit address of the originator of the packet. |
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175 |
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176 Destination Address 128-bit address of the intended recipient of the |
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177 packet (possibly not the ultimate recipient, if |
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178 a Routing header is present) |
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179 @endverbatim |
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180 * @publishedAll |
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181 * @released |
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182 * @since v7.0 |
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183 */ |
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184 { |
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185 public: |
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186 enum TOffsets |
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187 { |
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188 O_PayloadLength = 4, |
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189 O_NextHeader = 6, |
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190 O_HopLimit = 7, |
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191 O_SrcAddr = 8, |
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192 O_DstAddr = 24 |
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193 }; |
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194 |
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195 // Basic functions, common to all header classes |
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196 // ********************************************* |
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197 |
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198 /** |
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199 * Gets the header length. |
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200 * |
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201 * Note that the header length is fixed. |
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202 * |
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203 * @return Header length. |
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204 */ |
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205 inline TInt HeaderLength() const {return 40;} |
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206 /** |
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207 * Gets the minimum header length. |
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208 * |
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209 * Note that the header length is fixed. |
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210 * |
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211 * @return Minimum header length |
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212 */ |
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213 inline static TInt MinHeaderLength() {return 40; } |
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214 /** |
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215 * Gets the maximum header length. |
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216 * |
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217 * Note that the header length is fixed. |
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218 * |
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219 * @return Maximum header length |
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220 */ |
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221 inline static TInt MaxHeaderLength() {return 40; } |
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222 /** |
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223 * Gets a pointer to the byte following the header. |
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224 * |
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225 * @return Pointer to the byte following the header |
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226 */ |
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227 inline TUint8 *EndPtr() {return i + HeaderLength();} |
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228 |
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229 // IPv6 specific methods, get IP header field values from the packet |
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230 // ***************************************************************** |
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231 |
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232 inline TInt Version() const |
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233 /** |
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234 * Gets the IP version from the header. |
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235 * |
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236 * @return IP version |
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237 */ |
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238 { |
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239 return (i[0] >> 4) & 0xf; |
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240 } |
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241 inline TInt TrafficClass() const |
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242 /** |
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243 * Gets the traffic class from the header. |
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244 * |
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245 * @return Traffic class |
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246 */ |
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247 { |
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248 return ((i[0] << 4) & 0xf0) | ((i[1] >> 4) & 0x0f); |
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249 } |
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250 inline TInt FlowLabel() const |
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251 /** |
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252 * Gets the flow label from the header. |
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253 * |
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254 * @return Flow label (host byte order) |
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255 */ |
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256 { |
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257 return ((i[1] << 16) | (i[2] << 8) | i[3]) & 0xfffff; |
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258 // Could also use any deterministic permutation of the 20 bits, |
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259 // if Flow label can be treated as opaque 20 bits, and not as |
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260 // integer where host/net byte order comes into play --msa |
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261 } |
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262 inline TInt PayloadLength() const |
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263 /** |
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264 * Gets the payload length from the header. |
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265 * |
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266 * @return Payload length |
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267 */ |
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268 { |
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269 return (i[4] << 8) | i[5]; |
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270 } |
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271 inline TInt NextHeader() const |
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272 /** |
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273 * Gets the next header selector from the header. |
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274 * |
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275 * @return Next header selector (0..255) |
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276 */ |
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277 { |
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278 return i[6]; |
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279 } |
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280 inline TInt HopLimit() const |
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281 { |
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282 /** |
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283 * Gets the hop limit from the header. |
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284 * |
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285 * @return Hop limit (0..255) |
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286 */ |
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287 return i[7]; |
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288 } |
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289 // |
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290 // The following return a modifiable reference, so |
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291 // they can be used both for access and build. |
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292 // |
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293 inline TIp6Addr &SrcAddr() const |
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294 /** |
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295 * Gets the source address from the header. |
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296 * |
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297 * @return Source address |
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298 */ |
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299 { |
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300 return (TIp6Addr &)i[8]; |
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301 } |
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302 inline TIp6Addr &DstAddr() const |
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303 /** |
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304 * Gets the destination address from the header. |
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305 * |
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306 * @return Destination address |
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307 */ |
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308 { |
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309 return (TIp6Addr &)i[24]; |
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310 } |
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311 |
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312 inline TBool EcnIsCongestion() |
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313 /** |
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314 * Gets ECN congestion status. |
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315 * |
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316 * see RFC-3168 for details. |
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317 * |
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318 * @return True, if CE bit is set on an ECN capable packet. |
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319 */ |
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320 { |
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321 return ((TrafficClass() & 3) == 3); |
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322 } |
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323 |
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324 |
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325 // IPv6 specific methods, set IP header field values into the packet |
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326 // ***************************************************************** |
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327 |
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328 inline void Init() |
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329 /** |
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330 * Initialises the header to basic initial values. |
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331 * |
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332 * @li Version = 6 |
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333 * @li Traffic Class = 0 |
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334 * @li Flow Label = 0 |
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335 * @li Payload Length = 0 |
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336 * @li Next Header = 0 |
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337 * @li Hop Limit = 0 |
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338 * |
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339 * The Source and Destination address fields are not touched. |
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340 */ |
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341 { |
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342 static const union { TUint8 a[4]; TUint32 b;} x = { {6 << 4, 0, 0, 0} }; |
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343 (TUint32 &)i[0] = x.b; |
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344 (TUint32 &)i[4] = 0; |
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345 } |
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346 |
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347 |
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348 inline void SetVersion(TInt aVersion) |
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349 /** |
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350 * Sets the IP version in the header. |
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351 * |
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352 * @param aVersion IP version (0..15, = 6 for IPv6) |
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353 */ |
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354 { |
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355 i[0] = (TUint8)((i[0] & 0x0f) | ((aVersion << 4) & 0xf0)); |
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356 } |
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357 inline void SetTrafficClass(TInt aClass) |
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358 /** |
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359 * Sets the traffic class in the header. |
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360 * |
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361 * @param aClass Traffic class (0..255) |
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362 */ |
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363 { |
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364 i[0] = (TUint8)((i[0] & 0xf0) | (aClass >> 4) & 0x0f); |
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365 i[1] = (TUint8)((i[1] & 0x0f) | (aClass << 4) & 0xf0); |
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366 } |
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367 inline void SetFlowLabel(TInt aFlow) |
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368 /** |
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369 * Sets the flow label in the header. |
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370 * |
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371 * @param aFlow Flow label (20 bit integer in host order) |
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372 */ |
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373 { |
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374 i[1] = (TUint8)((i[1] & 0xf0) | ((aFlow >> 16) & 0x0f)); |
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375 i[2] = (TUint8)(aFlow >> 8); |
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376 i[3] = (TUint8)aFlow; |
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377 } |
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378 |
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379 inline void SetPayloadLength(TInt aLength) |
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380 /** |
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381 * Sets the payload length in the header. |
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382 * |
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383 * @param aLength Payload length |
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384 */ |
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385 { |
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386 i[4] = (TUint8)(aLength >> 8); |
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387 i[5] = (TUint8)aLength; |
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388 } |
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389 |
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390 inline void SetNextHeader(TInt aNextHeader) |
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391 /** |
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392 * Sets the next header selector from the header. |
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393 * |
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394 * @param aNextHeader Next header selector (0..255) |
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395 */ |
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396 { |
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397 i[6] = (TUint8)aNextHeader; |
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398 } |
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399 inline void SetHopLimit(TInt aLimit) |
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400 /** |
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401 * Sets the hop limit in the header. |
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402 * |
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403 * @param aLimit Hop limit (0..255) |
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404 */ |
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405 { |
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406 i[7] = (TUint8)aLimit; |
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407 } |
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408 inline void SetSrcAddr(const TIp6Addr &anAddr) |
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409 /** |
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410 * Sets the source address in the header. |
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411 * |
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412 * @param anAddr Source address |
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413 */ |
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414 { |
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415 (TIp6Addr &)i[8] = anAddr; |
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416 } |
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417 inline void SetDstAddr(const TIp6Addr &anAddr) |
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418 /** |
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419 * Sets the destination address in the header. |
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420 * |
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421 * @param anAddr Destination address |
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422 */ |
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423 { |
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424 (TIp6Addr &)i[24] = anAddr; |
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425 } |
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426 |
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427 private: |
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428 union |
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429 { |
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430 TUint8 i[40]; |
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431 TUint32 iAlign; // A dummy member to force the 4 byte alignment |
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432 }; |
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433 }; |
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434 |
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435 /** @} */ |
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436 #endif |