1 /* 2 * srtp_priv.h 3 * 4 * private internal data structures and functions for libSRTP 5 * 6 * David A. McGrew 7 * Cisco Systems, Inc. 8 */ 9 /* 10 * 11 * Copyright (c) 2001-2006 Cisco Systems, Inc. 12 * All rights reserved. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 18 * Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 21 * Redistributions in binary form must reproduce the above 22 * copyright notice, this list of conditions and the following 23 * disclaimer in the documentation and/or other materials provided 24 * with the distribution. 25 * 26 * Neither the name of the Cisco Systems, Inc. nor the names of its 27 * contributors may be used to endorse or promote products derived 28 * from this software without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 41 * OF THE POSSIBILITY OF SUCH DAMAGE. 42 * 43 */ 44 45 #ifndef SRTP_PRIV_H 46 #define SRTP_PRIV_H 47 48 #include "srtp.h" 49 #include "rdbx.h" 50 #include "rdb.h" 51 #include "integers.h" 52 53 /* 54 * an srtp_hdr_t represents the srtp header 55 * 56 * in this implementation, an srtp_hdr_t is assumed to be 32-bit aligned 57 * 58 * (note that this definition follows that of RFC 1889 Appendix A, but 59 * is not identical) 60 */ 61 62 #ifndef WORDS_BIGENDIAN 63 64 /* 65 * srtp_hdr_t represents an RTP or SRTP header. The bit-fields in 66 * this structure should be declared "unsigned int" instead of 67 * "unsigned char", but doing so causes the MS compiler to not 68 * fully pack the bit fields. 69 */ 70 71 typedef struct { 72 unsigned char cc:4; /* CSRC count */ 73 unsigned char x:1; /* header extension flag */ 74 unsigned char p:1; /* padding flag */ 75 unsigned char version:2; /* protocol version */ 76 unsigned char pt:7; /* payload type */ 77 unsigned char m:1; /* marker bit */ 78 uint16_t seq; /* sequence number */ 79 uint32_t ts; /* timestamp */ 80 uint32_t ssrc; /* synchronization source */ 81 } srtp_hdr_t; 82 83 #else /* BIG_ENDIAN */ 84 85 typedef struct { 86 unsigned char version:2; /* protocol version */ 87 unsigned char p:1; /* padding flag */ 88 unsigned char x:1; /* header extension flag */ 89 unsigned char cc:4; /* CSRC count */ 90 unsigned char m:1; /* marker bit */ 91 unsigned pt:7; /* payload type */ 92 uint16_t seq; /* sequence number */ 93 uint32_t ts; /* timestamp */ 94 uint32_t ssrc; /* synchronization source */ 95 } srtp_hdr_t; 96 97 #endif 98 99 typedef struct { 100 uint16_t profile_specific; /* profile-specific info */ 101 uint16_t length; /* number of 32-bit words in extension */ 102 } srtp_hdr_xtnd_t; 103 104 105 /* 106 * srtcp_hdr_t represents a secure rtcp header 107 * 108 * in this implementation, an srtcp header is assumed to be 32-bit 109 * alinged 110 */ 111 112 #ifndef WORDS_BIGENDIAN 113 114 typedef struct { 115 unsigned char rc:5; /* reception report count */ 116 unsigned char p:1; /* padding flag */ 117 unsigned char version:2; /* protocol version */ 118 unsigned char pt:8; /* payload type */ 119 uint16_t len; /* length */ 120 uint32_t ssrc; /* synchronization source */ 121 } srtcp_hdr_t; 122 123 typedef struct { 124 unsigned int index:31; /* srtcp packet index in network order! */ 125 unsigned int e:1; /* encrypted? 1=yes */ 126 /* optional mikey/etc go here */ 127 /* and then the variable-length auth tag */ 128 } srtcp_trailer_t; 129 130 131 #else /* BIG_ENDIAN */ 132 133 typedef struct { 134 unsigned char version:2; /* protocol version */ 135 unsigned char p:1; /* padding flag */ 136 unsigned char rc:5; /* reception report count */ 137 unsigned char pt:8; /* payload type */ 138 uint16_t len; /* length */ 139 uint32_t ssrc; /* synchronization source */ 140 } srtcp_hdr_t; 141 142 typedef struct { 143 unsigned int version:2; /* protocol version */ 144 unsigned int p:1; /* padding flag */ 145 unsigned int count:5; /* varies by packet type */ 146 unsigned int pt:8; /* payload type */ 147 uint16_t length; /* len of uint32s of packet less header */ 148 } rtcp_common_t; 149 150 typedef struct { 151 unsigned int e:1; /* encrypted? 1=yes */ 152 unsigned int index:31; /* srtcp packet index */ 153 /* optional mikey/etc go here */ 154 /* and then the variable-length auth tag */ 155 } srtcp_trailer_t; 156 157 #endif 158 159 160 /* 161 * the following declarations are libSRTP internal functions 162 */ 163 164 /* 165 * srtp_get_stream(ssrc) returns a pointer to the stream corresponding 166 * to ssrc, or NULL if no stream exists for that ssrc 167 */ 168 169 srtp_stream_t 170 srtp_get_stream(srtp_t srtp, uint32_t ssrc); 171 172 173 /* 174 * srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by 175 * deriving all of the needed keys using the KDF and the key k. 176 */ 177 178 179 err_status_t 180 srtp_stream_init_keys(srtp_stream_t srtp, const void *key); 181 182 /* 183 * srtp_stream_init(s, p) initializes the srtp_stream_t s to 184 * use the policy at the location p 185 */ 186 err_status_t 187 srtp_stream_init(srtp_stream_t srtp, 188 const srtp_policy_t *p); 189 190 191 /* 192 * libsrtp internal datatypes 193 */ 194 195 typedef enum direction_t { 196 dir_unknown = 0, 197 dir_srtp_sender = 1, 198 dir_srtp_receiver = 2 199 } direction_t; 200 201 /* 202 * an srtp_stream_t has its own SSRC, encryption key, authentication 203 * key, sequence number, and replay database 204 * 205 * note that the keys might not actually be unique, in which case the 206 * cipher_t and auth_t pointers will point to the same structures 207 */ 208 209 typedef struct srtp_stream_ctx_t { 210 uint32_t ssrc; 211 cipher_t *rtp_cipher; 212 auth_t *rtp_auth; 213 rdbx_t rtp_rdbx; 214 sec_serv_t rtp_services; 215 cipher_t *rtcp_cipher; 216 auth_t *rtcp_auth; 217 rdb_t rtcp_rdb; 218 sec_serv_t rtcp_services; 219 key_limit_ctx_t *limit; 220 direction_t direction; 221 int allow_repeat_tx; 222 ekt_stream_t ekt; 223 struct srtp_stream_ctx_t *next; /* linked list of streams */ 224 } srtp_stream_ctx_t; 225 226 227 /* 228 * an srtp_ctx_t holds a stream list and a service description 229 */ 230 231 typedef struct srtp_ctx_t { 232 srtp_stream_ctx_t *stream_list; /* linked list of streams */ 233 srtp_stream_ctx_t *stream_template; /* act as template for other streams */ 234 } srtp_ctx_t; 235 236 237 238 /* 239 * srtp_handle_event(srtp, srtm, evnt) calls the event handling 240 * function, if there is one. 241 * 242 * This macro is not included in the documentation as it is 243 * an internal-only function. 244 */ 245 246 #define srtp_handle_event(srtp, strm, evnt) \ 247 if(srtp_event_handler) { \ 248 srtp_event_data_t data; \ 249 data.session = srtp; \ 250 data.stream = strm; \ 251 data.event = evnt; \ 252 srtp_event_handler(&data); \ 253 } 254 255 256 #endif /* SRTP_PRIV_H */ 257
