srtp_priv.h 7.5 KB

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  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. #ifndef SRTP_PRIV_H
  45. #define SRTP_PRIV_H
  46. #include "srtp.h"
  47. #include "rdbx.h"
  48. #include "rdb.h"
  49. #include "integers.h"
  50. /*
  51. * an srtp_hdr_t represents the srtp header
  52. *
  53. * in this implementation, an srtp_hdr_t is assumed to be 32-bit aligned
  54. *
  55. * (note that this definition follows that of RFC 1889 Appendix A, but
  56. * is not identical)
  57. */
  58. #ifndef WORDS_BIGENDIAN
  59. /*
  60. * srtp_hdr_t represents an RTP or SRTP header. The bit-fields in
  61. * this structure should be declared "unsigned int" instead of
  62. * "unsigned char", but doing so causes the MS compiler to not
  63. * fully pack the bit fields.
  64. */
  65. typedef struct {
  66. unsigned cc:4; /* CSRC count */
  67. unsigned x:1; /* header extension flag */
  68. unsigned p:1; /* padding flag */
  69. unsigned version:2; /* protocol version */
  70. unsigned pt:7; /* payload type */
  71. unsigned m:1; /* marker bit */
  72. unsigned seq:16; /* sequence number */
  73. unsigned ts:32; /* timestamp */
  74. uint32_t ssrc; /* synchronization source */
  75. } srtp_hdr_t;
  76. #else /* BIG_ENDIAN */
  77. typedef struct {
  78. unsigned version:2; /* protocol version */
  79. unsigned p:1; /* padding flag */
  80. unsigned x:1; /* header extension flag */
  81. unsigned cc:4; /* CSRC count */
  82. unsigned m:1; /* marker bit */
  83. unsigned pt:7; /* payload type */
  84. unsigned seq:16; /* sequence number */
  85. unsigned ts:32; /* timestamp */
  86. uint32_t ssrc; /* synchronization source */
  87. } srtp_hdr_t;
  88. #endif
  89. typedef struct {
  90. uint16_t profile_specific; /* profile-specific info */
  91. uint16_t length; /* number of 32-bit words in extension */
  92. } srtp_hdr_xtnd_t;
  93. /*
  94. * srtcp_hdr_t represents a secure rtcp header
  95. *
  96. * in this implementation, an srtcp header is assumed to be 32-bit
  97. * alinged
  98. */
  99. #ifndef WORDS_BIGENDIAN
  100. typedef struct {
  101. unsigned rc:5; /* reception report count */
  102. unsigned p:1; /* padding flag */
  103. unsigned version:2; /* protocol version */
  104. unsigned pt:8; /* payload type */
  105. unsigned len:16; /* length */
  106. uint32_t ssrc; /* synchronization source */
  107. } srtcp_hdr_t;
  108. typedef struct {
  109. unsigned int index:31; /* srtcp packet index in network order! */
  110. unsigned int e:1; /* encrypted? 1=yes */
  111. /* optional mikey/etc go here */
  112. /* and then the variable-length auth tag */
  113. } srtcp_trailer_t;
  114. #else /* BIG_ENDIAN */
  115. typedef struct {
  116. unsigned version:2; /* protocol version */
  117. unsigned p:1; /* padding flag */
  118. unsigned rc:5; /* reception report count */
  119. unsigned pt:8; /* payload type */
  120. uint16_t len; /* length */
  121. uint32_t ssrc; /* synchronization source */
  122. } srtcp_hdr_t;
  123. typedef struct {
  124. unsigned int version:2; /* protocol version */
  125. unsigned int p:1; /* padding flag */
  126. unsigned int count:5; /* varies by packet type */
  127. unsigned int pt:8; /* payload type */
  128. uint16_t length; /* len of uint32s of packet less header */
  129. } rtcp_common_t;
  130. typedef struct {
  131. unsigned int e:1; /* encrypted? 1=yes */
  132. unsigned int index:31; /* srtcp packet index */
  133. /* optional mikey/etc go here */
  134. /* and then the variable-length auth tag */
  135. } srtcp_trailer_t;
  136. #endif
  137. /*
  138. * the following declarations are libSRTP internal functions
  139. */
  140. /*
  141. * srtp_get_stream(ssrc) returns a pointer to the stream corresponding
  142. * to ssrc, or NULL if no stream exists for that ssrc
  143. */
  144. srtp_stream_t
  145. srtp_get_stream(srtp_t srtp, uint32_t ssrc);
  146. /*
  147. * srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by
  148. * deriving all of the needed keys using the KDF and the key k.
  149. */
  150. err_status_t
  151. srtp_stream_init_keys(srtp_stream_t srtp, const void *key);
  152. /*
  153. * srtp_stream_init(s, p) initializes the srtp_stream_t s to
  154. * use the policy at the location p
  155. */
  156. err_status_t
  157. srtp_stream_init(srtp_stream_t srtp,
  158. const srtp_policy_t *p);
  159. /*
  160. * libsrtp internal datatypes
  161. */
  162. typedef enum direction_t {
  163. dir_unknown = 0,
  164. dir_srtp_sender = 1,
  165. dir_srtp_receiver = 2
  166. } direction_t;
  167. /*
  168. * an srtp_stream_t has its own SSRC, encryption key, authentication
  169. * key, sequence number, and replay database
  170. *
  171. * note that the keys might not actually be unique, in which case the
  172. * cipher_t and auth_t pointers will point to the same structures
  173. */
  174. typedef struct srtp_stream_ctx_t {
  175. uint32_t ssrc;
  176. cipher_t *rtp_cipher;
  177. auth_t *rtp_auth;
  178. rdbx_t rtp_rdbx;
  179. sec_serv_t rtp_services;
  180. cipher_t *rtcp_cipher;
  181. auth_t *rtcp_auth;
  182. rdb_t rtcp_rdb;
  183. sec_serv_t rtcp_services;
  184. key_limit_ctx_t *limit;
  185. direction_t direction;
  186. int allow_repeat_tx;
  187. ekt_stream_t ekt;
  188. uint8_t salt[SRTP_AEAD_SALT_LEN]; /* used with GCM mode for SRTP */
  189. uint8_t c_salt[SRTP_AEAD_SALT_LEN]; /* used with GCM mode for SRTCP */
  190. struct srtp_stream_ctx_t *next; /* linked list of streams */
  191. } srtp_stream_ctx_t;
  192. /*
  193. * an srtp_ctx_t holds a stream list and a service description
  194. */
  195. typedef struct srtp_ctx_t {
  196. srtp_stream_ctx_t *stream_list; /* linked list of streams */
  197. srtp_stream_ctx_t *stream_template; /* act as template for other streams */
  198. } srtp_ctx_t;
  199. /*
  200. * srtp_handle_event(srtp, srtm, evnt) calls the event handling
  201. * function, if there is one.
  202. *
  203. * This macro is not included in the documentation as it is
  204. * an internal-only function.
  205. */
  206. #define srtp_handle_event(srtp, strm, evnt) \
  207. if(srtp_event_handler) { \
  208. srtp_event_data_t data; \
  209. data.session = srtp; \
  210. data.stream = strm; \
  211. data.event = evnt; \
  212. srtp_event_handler(&data); \
  213. }
  214. #endif /* SRTP_PRIV_H */