/* * 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 srtp_sequence_number_t; /* 16 bit sequence number */ 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 … #define seq_num_max … /* * An rtp_xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended' * sequence number. */ 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. */ 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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