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/*
* srtp_priv.h
*
* private internal data structures and functions for libSRTP
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright (c) 2001-2006 Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Cisco Systems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef SRTP_PRIV_H
#define SRTP_PRIV_H
#include "srtp.h"
#include "rdbx.h"
#include "rdb.h"
#include "integers.h"
/*
* an srtp_hdr_t represents the srtp header
*
* in this implementation, an srtp_hdr_t is assumed to be 32-bit aligned
*
* (note that this definition follows that of RFC 1889 Appendix A, but
* is not identical)
*/
#ifndef WORDS_BIGENDIAN
/*
* srtp_hdr_t represents an RTP or SRTP header. The bit-fields in
* this structure should be declared "unsigned int" instead of
* "unsigned char", but doing so causes the MS compiler to not
* fully pack the bit fields.
*/
typedef struct {
unsigned char cc:4; /* CSRC count */
unsigned char x:1; /* header extension flag */
unsigned char p:1; /* padding flag */
unsigned char version:2; /* protocol version */
unsigned char pt:7; /* payload type */
unsigned char m:1; /* marker bit */
uint16_t seq; /* sequence number */
uint32_t ts; /* timestamp */
uint32_t ssrc; /* synchronization source */
} srtp_hdr_t;
#else /* BIG_ENDIAN */
typedef struct {
unsigned char version:2; /* protocol version */
unsigned char p:1; /* padding flag */
unsigned char x:1; /* header extension flag */
unsigned char cc:4; /* CSRC count */
unsigned char m:1; /* marker bit */
unsigned pt:7; /* payload type */
uint16_t seq; /* sequence number */
uint32_t ts; /* timestamp */
uint32_t ssrc; /* synchronization source */
} srtp_hdr_t;
#endif
typedef struct {
uint16_t profile_specific; /* profile-specific info */
uint16_t length; /* number of 32-bit words in extension */
} srtp_hdr_xtnd_t;
/*
* srtcp_hdr_t represents a secure rtcp header
*
* in this implementation, an srtcp header is assumed to be 32-bit
* alinged
*/
#ifndef WORDS_BIGENDIAN
typedef struct {
unsigned char rc:5; /* reception report count */
unsigned char p:1; /* padding flag */
unsigned char version:2; /* protocol version */
unsigned char pt:8; /* payload type */
uint16_t len; /* length */
uint32_t ssrc; /* synchronization source */
} srtcp_hdr_t;
typedef struct {
unsigned int index:31; /* srtcp packet index in network order! */
unsigned int e:1; /* encrypted? 1=yes */
/* optional mikey/etc go here */
/* and then the variable-length auth tag */
} srtcp_trailer_t;
#else /* BIG_ENDIAN */
typedef struct {
unsigned char version:2; /* protocol version */
unsigned char p:1; /* padding flag */
unsigned char rc:5; /* reception report count */
unsigned char pt:8; /* payload type */
uint16_t len; /* length */
uint32_t ssrc; /* synchronization source */
} srtcp_hdr_t;
typedef struct {
unsigned int version:2; /* protocol version */
unsigned int p:1; /* padding flag */
unsigned int count:5; /* varies by packet type */
unsigned int pt:8; /* payload type */
uint16_t length; /* len of uint32s of packet less header */
} rtcp_common_t;
typedef struct {
unsigned int e:1; /* encrypted? 1=yes */
unsigned int index:31; /* srtcp packet index */
/* optional mikey/etc go here */
/* and then the variable-length auth tag */
} srtcp_trailer_t;
#endif
/*
* the following declarations are libSRTP internal functions
*/
/*
* srtp_get_stream(ssrc) returns a pointer to the stream corresponding
* to ssrc, or NULL if no stream exists for that ssrc
*/
srtp_stream_t
srtp_get_stream(srtp_t srtp, uint32_t ssrc);
/*
* srtp_stream_init_keys(s, k) (re)initializes the srtp_stream_t s by
* deriving all of the needed keys using the KDF and the key k.
*/
err_status_t
srtp_stream_init_keys(srtp_stream_t srtp, const void *key);
/*
* srtp_stream_init(s, p) initializes the srtp_stream_t s to
* use the policy at the location p
*/
err_status_t
srtp_stream_init(srtp_stream_t srtp,
const srtp_policy_t *p);
/*
* libsrtp internal datatypes
*/
typedef enum direction_t {
dir_unknown = 0,
dir_srtp_sender = 1,
dir_srtp_receiver = 2
} direction_t;
/*
* an srtp_stream_t has its own SSRC, encryption key, authentication
* key, sequence number, and replay database
*
* note that the keys might not actually be unique, in which case the
* cipher_t and auth_t pointers will point to the same structures
*/
typedef struct srtp_stream_ctx_t {
uint32_t ssrc;
cipher_t *rtp_cipher;
auth_t *rtp_auth;
rdbx_t rtp_rdbx;
sec_serv_t rtp_services;
cipher_t *rtcp_cipher;
auth_t *rtcp_auth;
rdb_t rtcp_rdb;
sec_serv_t rtcp_services;
key_limit_ctx_t *limit;
direction_t direction;
int allow_repeat_tx;
ekt_stream_t ekt;
struct srtp_stream_ctx_t *next; /* linked list of streams */
} srtp_stream_ctx_t;
/*
* an srtp_ctx_t holds a stream list and a service description
*/
typedef struct srtp_ctx_t {
srtp_stream_ctx_t *stream_list; /* linked list of streams */
srtp_stream_ctx_t *stream_template; /* act as template for other streams */
} srtp_ctx_t;
/*
* srtp_handle_event(srtp, srtm, evnt) calls the event handling
* function, if there is one.
*
* This macro is not included in the documentation as it is
* an internal-only function.
*/
#define srtp_handle_event(srtp, strm, evnt) \
if(srtp_event_handler) { \
srtp_event_data_t data; \
data.session = srtp; \
data.stream = strm; \
data.event = evnt; \
srtp_event_handler(&data); \
}
#endif /* SRTP_PRIV_H */
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