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/*
* rdbx.h
*
* replay database with extended packet indices, using a rollover counter
*
* David A. McGrew
* Cisco Systems, Inc.
*
*/
/*
*
* Copyright (c) 2001-2017, 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 RDBX_H
#define RDBX_H
#include "datatypes.h"
#include "err.h"
#ifdef __cplusplus
extern "C" {
#endif
/* #define ROC_TEST */
#ifndef ROC_TEST
typedef uint16_t srtp_sequence_number_t; /* 16 bit sequence number */
typedef uint32_t srtp_rollover_counter_t; /* 32 bit rollover counter */
#else /* use small seq_num and roc datatypes for testing purposes */
typedef unsigned char srtp_sequence_number_t; /* 8 bit sequence number */
typedef uint16_t srtp_rollover_counter_t; /* 16 bit rollover counter */
#endif
#define seq_num_median (1 << (8 * sizeof(srtp_sequence_number_t) - 1))
#define seq_num_max (1 << (8 * sizeof(srtp_sequence_number_t)))
/*
* An rtp_xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended'
* sequence number.
*/
typedef uint64_t srtp_xtd_seq_num_t;
/*
* An srtp_rdbx_t is a replay database with extended range; it uses an
* xtd_seq_num_t and a bitmask of recently received indices.
*/
typedef struct {
srtp_xtd_seq_num_t index;
bitvector_t bitmask;
} srtp_rdbx_t;
/*
* srtp_rdbx_init(rdbx_ptr, ws)
*
* initializes the rdbx pointed to by its argument with the window size ws,
* setting the rollover counter and sequence number to zero
*/
srtp_err_status_t srtp_rdbx_init(srtp_rdbx_t *rdbx, unsigned long ws);
/*
* srtp_rdbx_dealloc(rdbx_ptr)
*
* frees memory associated with the rdbx
*/
srtp_err_status_t srtp_rdbx_dealloc(srtp_rdbx_t *rdbx);
/*
* srtp_rdbx_estimate_index(rdbx, guess, s)
*
* given an rdbx and a sequence number s (from a newly arrived packet),
* sets the contents of *guess to contain the best guess of the packet
* index to which s corresponds, and returns the difference between
* *guess and the locally stored synch info
*/
int32_t srtp_rdbx_estimate_index(const srtp_rdbx_t *rdbx,
srtp_xtd_seq_num_t *guess,
srtp_sequence_number_t s);
/*
* srtp_rdbx_check(rdbx, delta);
*
* srtp_rdbx_check(&r, delta) checks to see if the xtd_seq_num_t
* which is at rdbx->window_start + delta is in the rdb
*
*/
srtp_err_status_t srtp_rdbx_check(const srtp_rdbx_t *rdbx, int difference);
/*
* srtp_replay_add_index(rdbx, delta)
*
* adds the srtp_xtd_seq_num_t at rdbx->window_start + delta to replay_db
* (and does *not* check if that xtd_seq_num_t appears in db)
*
* this function should be called *only* after replay_check has
* indicated that the index does not appear in the rdbx, and a mutex
* should protect the rdbx between these calls if necessary.
*/
srtp_err_status_t srtp_rdbx_add_index(srtp_rdbx_t *rdbx, int delta);
/*
* srtp_rdbx_set_roc(rdbx, roc) initalizes the srtp_rdbx_t at the location rdbx
* to have the rollover counter value roc. If that value is less than
* the current rollover counter value, then the function returns
* srtp_err_status_replay_old; otherwise, srtp_err_status_ok is returned.
*
*/
srtp_err_status_t srtp_rdbx_set_roc(srtp_rdbx_t *rdbx, uint32_t roc);
/*
* srtp_rdbx_get_packet_index(rdbx) returns the value of the rollover counter
* for
* the srtp_rdbx_t pointed to by rdbx
*
*/
srtp_xtd_seq_num_t srtp_rdbx_get_packet_index(const srtp_rdbx_t *rdbx);
/*
* srtp_xtd_seq_num_t functions - these are *internal* functions of rdbx, and
* shouldn't be used to manipulate rdbx internal values. use the rdbx
* api instead!
*/
/*
* srtp_rdbx_get_ws(rdbx_ptr)
*
* gets the window size which was used to initialize the rdbx
*/
unsigned long srtp_rdbx_get_window_size(const srtp_rdbx_t *rdbx);
/* index_init(&pi) initializes a packet index pi (sets it to zero) */
void srtp_index_init(srtp_xtd_seq_num_t *pi);
/* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */
void srtp_index_advance(srtp_xtd_seq_num_t *pi, srtp_sequence_number_t s);
/*
* srtp_index_guess(local, guess, s)
*
* given a srtp_xtd_seq_num_t local (which represents the highest
* known-to-be-good index) and a sequence number s (from a newly
* arrived packet), sets the contents of *guess to contain the best
* guess of the packet index to which s corresponds, and returns the
* difference between *guess and *local
*/
int32_t srtp_index_guess(const srtp_xtd_seq_num_t *local,
srtp_xtd_seq_num_t *guess,
srtp_sequence_number_t s);
/*
* srtp_rdbx_get_roc(rdbx)
*
* Get the current rollover counter
*
*/
uint32_t srtp_rdbx_get_roc(const srtp_rdbx_t *rdbx);
/*
* srtp_rdbx_set_roc_seq(rdbx, roc, seq) initalizes the srtp_rdbx_t at the
* location rdbx to have the rollover counter value roc and packet sequence
* number seq. If the new rollover counter value is less than the current
* rollover counter value, then the function returns
* srtp_err_status_replay_old, otherwise, srtp_err_status_ok is returned.
*/
srtp_err_status_t srtp_rdbx_set_roc_seq(srtp_rdbx_t *rdbx,
uint32_t roc,
uint16_t seq);
#ifdef __cplusplus
}
#endif
#endif /* RDBX_H */
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