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1 /* |
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2 * srtp_priv.h |
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3 * |
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4 * private internal data structures and functions for libSRTP |
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5 * |
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6 * David A. McGrew |
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7 * Cisco Systems, Inc. |
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8 */ |
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9 /* |
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10 * |
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11 * Copyright (c) 2001-2006 Cisco Systems, Inc. |
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12 * All rights reserved. |
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13 * |
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14 * Redistribution and use in source and binary forms, with or without |
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15 * modification, are permitted provided that the following conditions |
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16 * are met: |
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17 * |
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18 * Redistributions of source code must retain the above copyright |
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19 * notice, this list of conditions and the following disclaimer. |
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20 * |
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21 * Redistributions in binary form must reproduce the above |
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22 * copyright notice, this list of conditions and the following |
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23 * disclaimer in the documentation and/or other materials provided |
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24 * with the distribution. |
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25 * |
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26 * Neither the name of the Cisco Systems, Inc. nor the names of its |
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27 * contributors may be used to endorse or promote products derived |
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28 * from this software without specific prior written permission. |
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29 * |
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30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
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35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
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37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
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41 * OF THE POSSIBILITY OF SUCH DAMAGE. |
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42 * |
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43 */ |
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44 |
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45 #ifndef SRTP_PRIV_H |
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46 #define SRTP_PRIV_H |
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47 |
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48 #include "srtp.h" |
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49 #include "rdbx.h" |
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50 #include "rdb.h" |
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51 #include "integers.h" |
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52 |
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53 /* |
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54 * an srtp_hdr_t represents the srtp header |
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55 * |
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56 * in this implementation, an srtp_hdr_t is assumed to be 32-bit aligned |
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57 * |
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58 * (note that this definition follows that of RFC 1889 Appendix A, but |
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59 * is not identical) |
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60 */ |
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61 |
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62 #ifndef WORDS_BIGENDIAN |
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63 |
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64 /* |
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65 * srtp_hdr_t represents an RTP or SRTP header. The bit-fields in |
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66 * this structure should be declared "unsigned int" instead of |
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67 * "unsigned char", but doing so causes the MS compiler to not |
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68 * fully pack the bit fields. |
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69 */ |
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70 |
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71 typedef struct { |
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72 unsigned char cc:4; /* CSRC count */ |
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73 unsigned char x:1; /* header extension flag */ |
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74 unsigned char p:1; /* padding flag */ |
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75 unsigned char version:2; /* protocol version */ |
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76 unsigned char pt:7; /* payload type */ |
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77 unsigned char m:1; /* marker bit */ |
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78 uint16_t seq; /* sequence number */ |
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79 uint32_t ts; /* timestamp */ |
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80 uint32_t ssrc; /* synchronization source */ |
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81 } srtp_hdr_t; |
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82 |
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83 #else /* BIG_ENDIAN */ |
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84 |
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85 typedef struct { |
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86 unsigned char version:2; /* protocol version */ |
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87 unsigned char p:1; /* padding flag */ |
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88 unsigned char x:1; /* header extension flag */ |
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89 unsigned char cc:4; /* CSRC count */ |
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90 unsigned char m:1; /* marker bit */ |
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91 unsigned pt:7; /* payload type */ |
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92 uint16_t seq; /* sequence number */ |
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93 uint32_t ts; /* timestamp */ |
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94 uint32_t ssrc; /* synchronization source */ |
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95 } srtp_hdr_t; |
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96 |
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97 #endif |
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98 |
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99 typedef struct { |
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100 uint16_t profile_specific; /* profile-specific info */ |
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101 uint16_t length; /* number of 32-bit words in extension */ |
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102 } srtp_hdr_xtnd_t; |
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103 |
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104 |
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105 /* |
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106 * srtcp_hdr_t represents a secure rtcp header |
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107 * |
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108 * in this implementation, an srtcp header is assumed to be 32-bit |
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109 * alinged |
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110 */ |
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111 |
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112 #ifndef WORDS_BIGENDIAN |
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113 |
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114 typedef struct { |
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115 unsigned char rc:5; /* reception report count */ |
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116 unsigned char p:1; /* padding flag */ |
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117 unsigned char version:2; /* protocol version */ |
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118 unsigned char pt:8; /* payload type */ |
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119 uint16_t len; /* length */ |
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120 uint32_t ssrc; /* synchronization source */ |
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121 } srtcp_hdr_t; |
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122 |
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123 typedef struct { |
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124 unsigned int index:31; /* srtcp packet index in network order! */ |
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125 unsigned int e:1; /* encrypted? 1=yes */ |
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126 /* optional mikey/etc go here */ |
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127 /* and then the variable-length auth tag */ |
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128 } srtcp_trailer_t; |
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129 |
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130 |
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131 #else /* BIG_ENDIAN */ |
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132 |
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133 typedef struct { |
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134 unsigned char version:2; /* protocol version */ |
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135 unsigned char p:1; /* padding flag */ |
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136 unsigned char rc:5; /* reception report count */ |
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137 unsigned char pt:8; /* payload type */ |
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138 uint16_t len; /* length */ |
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139 uint32_t ssrc; /* synchronization source */ |
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140 } srtcp_hdr_t; |
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141 |
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142 typedef struct { |
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143 unsigned int version:2; /* protocol version */ |
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144 unsigned int p:1; /* padding flag */ |
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145 unsigned int count:5; /* varies by packet type */ |
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146 unsigned int pt:8; /* payload type */ |
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147 uint16_t length; /* len of uint32s of packet less header */ |
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148 } rtcp_common_t; |
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149 |
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150 typedef struct { |
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151 unsigned int e:1; /* encrypted? 1=yes */ |
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152 unsigned int index:31; /* srtcp packet index */ |
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153 /* optional mikey/etc go here */ |
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154 /* and then the variable-length auth tag */ |
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155 } srtcp_trailer_t; |
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156 |
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157 #endif |
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158 |
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159 |
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160 /* |
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161 * the following declarations are libSRTP internal functions |
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162 */ |
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163 |
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164 /* |
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165 * srtp_get_stream(ssrc) returns a pointer to the stream corresponding |
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166 * to ssrc, or NULL if no stream exists for that ssrc |
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167 */ |
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168 |
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169 srtp_stream_t |
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170 srtp_get_stream(srtp_t srtp, uint32_t ssrc); |
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171 |
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172 |
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173 /* |
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174 * srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by |
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175 * deriving all of the needed keys using the KDF and the key k. |
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176 */ |
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177 |
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178 |
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179 err_status_t |
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180 srtp_stream_init_keys(srtp_stream_t srtp, const void *key); |
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181 |
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182 /* |
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183 * srtp_stream_init(s, p) initializes the srtp_stream_t s to |
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184 * use the policy at the location p |
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185 */ |
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186 err_status_t |
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187 srtp_stream_init(srtp_stream_t srtp, |
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188 const srtp_policy_t *p); |
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189 |
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190 |
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191 /* |
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192 * libsrtp internal datatypes |
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193 */ |
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194 |
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195 typedef enum direction_t { |
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196 dir_unknown = 0, |
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197 dir_srtp_sender = 1, |
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198 dir_srtp_receiver = 2 |
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199 } direction_t; |
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200 |
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201 /* |
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202 * an srtp_stream_t has its own SSRC, encryption key, authentication |
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203 * key, sequence number, and replay database |
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204 * |
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205 * note that the keys might not actually be unique, in which case the |
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206 * cipher_t and auth_t pointers will point to the same structures |
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207 */ |
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208 |
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209 typedef struct srtp_stream_ctx_t { |
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210 uint32_t ssrc; |
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211 cipher_t *rtp_cipher; |
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212 auth_t *rtp_auth; |
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213 rdbx_t rtp_rdbx; |
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214 sec_serv_t rtp_services; |
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215 cipher_t *rtcp_cipher; |
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216 auth_t *rtcp_auth; |
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217 rdb_t rtcp_rdb; |
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218 sec_serv_t rtcp_services; |
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219 key_limit_ctx_t *limit; |
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220 direction_t direction; |
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221 int allow_repeat_tx; |
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222 ekt_stream_t ekt; |
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223 struct srtp_stream_ctx_t *next; /* linked list of streams */ |
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224 } srtp_stream_ctx_t; |
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225 |
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226 |
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227 /* |
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228 * an srtp_ctx_t holds a stream list and a service description |
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229 */ |
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230 |
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231 typedef struct srtp_ctx_t { |
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232 srtp_stream_ctx_t *stream_list; /* linked list of streams */ |
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233 srtp_stream_ctx_t *stream_template; /* act as template for other streams */ |
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234 } srtp_ctx_t; |
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235 |
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236 |
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237 |
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238 /* |
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239 * srtp_handle_event(srtp, srtm, evnt) calls the event handling |
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240 * function, if there is one. |
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241 * |
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242 * This macro is not included in the documentation as it is |
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243 * an internal-only function. |
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244 */ |
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245 |
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246 #define srtp_handle_event(srtp, strm, evnt) \ |
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247 if(srtp_event_handler) { \ |
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248 srtp_event_data_t data; \ |
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249 data.session = srtp; \ |
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250 data.stream = strm; \ |
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251 data.event = evnt; \ |
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252 srtp_event_handler(&data); \ |
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253 } |
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254 |
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255 |
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256 #endif /* SRTP_PRIV_H */ |