212 lines
6.5 KiB
C
212 lines
6.5 KiB
C
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/*
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* rdbx.h
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*
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* replay database with extended packet indices, using a rollover counter
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*
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* David A. McGrew
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* Cisco Systems, Inc.
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*
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*/
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/*
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*
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* Copyright (c) 2001-2017, Cisco Systems, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* Neither the name of the Cisco Systems, Inc. nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifndef RDBX_H
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#define RDBX_H
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#include "datatypes.h"
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#include "err.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* #define ROC_TEST */
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#ifndef ROC_TEST
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typedef uint16_t srtp_sequence_number_t; /* 16 bit sequence number */
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typedef uint32_t srtp_rollover_counter_t; /* 32 bit rollover counter */
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#else /* use small seq_num and roc datatypes for testing purposes */
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typedef unsigned char srtp_sequence_number_t; /* 8 bit sequence number */
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typedef uint16_t srtp_rollover_counter_t; /* 16 bit rollover counter */
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#endif
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#define seq_num_median (1 << (8 * sizeof(srtp_sequence_number_t) - 1))
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#define seq_num_max (1 << (8 * sizeof(srtp_sequence_number_t)))
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/*
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* An rtp_xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended'
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* sequence number.
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*/
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typedef uint64_t srtp_xtd_seq_num_t;
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/*
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* An srtp_rdbx_t is a replay database with extended range; it uses an
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* xtd_seq_num_t and a bitmask of recently received indices.
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*/
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typedef struct {
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srtp_xtd_seq_num_t index;
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bitvector_t bitmask;
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} srtp_rdbx_t;
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/*
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* srtp_rdbx_init(rdbx_ptr, ws)
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*
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* initializes the rdbx pointed to by its argument with the window size ws,
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* setting the rollover counter and sequence number to zero
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*/
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srtp_err_status_t srtp_rdbx_init(srtp_rdbx_t *rdbx, unsigned long ws);
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/*
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* srtp_rdbx_dealloc(rdbx_ptr)
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*
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* frees memory associated with the rdbx
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*/
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srtp_err_status_t srtp_rdbx_dealloc(srtp_rdbx_t *rdbx);
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/*
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* srtp_rdbx_estimate_index(rdbx, guess, s)
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*
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* given an rdbx and a sequence number s (from a newly arrived packet),
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* sets the contents of *guess to contain the best guess of the packet
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* index to which s corresponds, and returns the difference between
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* *guess and the locally stored synch info
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*/
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int32_t srtp_rdbx_estimate_index(const srtp_rdbx_t *rdbx, srtp_xtd_seq_num_t *guess, srtp_sequence_number_t s);
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/*
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* srtp_rdbx_check(rdbx, delta);
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*
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* srtp_rdbx_check(&r, delta) checks to see if the xtd_seq_num_t
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* which is at rdbx->window_start + delta is in the rdb
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*
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*/
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srtp_err_status_t srtp_rdbx_check(const srtp_rdbx_t *rdbx, int difference);
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/*
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* srtp_replay_add_index(rdbx, delta)
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*
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* adds the srtp_xtd_seq_num_t at rdbx->window_start + delta to replay_db
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* (and does *not* check if that xtd_seq_num_t appears in db)
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*
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* this function should be called *only* after replay_check has
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* indicated that the index does not appear in the rdbx, and a mutex
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* should protect the rdbx between these calls if necessary.
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*/
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srtp_err_status_t srtp_rdbx_add_index(srtp_rdbx_t *rdbx, int delta);
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/*
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* srtp_rdbx_set_roc(rdbx, roc) initalizes the srtp_rdbx_t at the location rdbx
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* to have the rollover counter value roc. If that value is less than
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* the current rollover counter value, then the function returns
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* srtp_err_status_replay_old; otherwise, srtp_err_status_ok is returned.
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*
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*/
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srtp_err_status_t srtp_rdbx_set_roc(srtp_rdbx_t *rdbx, uint32_t roc);
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/*
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* srtp_rdbx_get_packet_index(rdbx) returns the value of the rollover counter for
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* the srtp_rdbx_t pointed to by rdbx
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*
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*/
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srtp_xtd_seq_num_t srtp_rdbx_get_packet_index(const srtp_rdbx_t *rdbx);
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/*
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* srtp_xtd_seq_num_t functions - these are *internal* functions of rdbx, and
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* shouldn't be used to manipulate rdbx internal values. use the rdbx
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* api instead!
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*/
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/*
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* srtp_rdbx_get_ws(rdbx_ptr)
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*
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* gets the window size which was used to initialize the rdbx
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*/
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unsigned long srtp_rdbx_get_window_size(const srtp_rdbx_t *rdbx);
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/* index_init(&pi) initializes a packet index pi (sets it to zero) */
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void srtp_index_init(srtp_xtd_seq_num_t *pi);
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/* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */
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void srtp_index_advance(srtp_xtd_seq_num_t *pi, srtp_sequence_number_t s);
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/*
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* srtp_index_guess(local, guess, s)
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*
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* given a srtp_xtd_seq_num_t local (which represents the highest
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* known-to-be-good index) and a sequence number s (from a newly
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* arrived packet), sets the contents of *guess to contain the best
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* guess of the packet index to which s corresponds, and returns the
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* difference between *guess and *local
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*/
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int32_t srtp_index_guess(const srtp_xtd_seq_num_t *local, srtp_xtd_seq_num_t *guess, srtp_sequence_number_t s);
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/*
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* srtp_rdbx_get_roc(rdbx)
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*
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* Get the current rollover counter
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*
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*/
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uint32_t srtp_rdbx_get_roc(const srtp_rdbx_t *rdbx);
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/*
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* srtp_rdbx_set_roc_seq(rdbx, roc, seq) initalizes the srtp_rdbx_t at the
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* location rdbx to have the rollover counter value roc and packet sequence
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* number seq. If the new rollover counter value is less than the current
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* rollover counter value, then the function returns
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* srtp_err_status_replay_old, otherwise, srtp_err_status_ok is returned.
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*/
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srtp_err_status_t srtp_rdbx_set_roc_seq (srtp_rdbx_t *rdbx,
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uint32_t roc,
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uint16_t seq);
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#ifdef __cplusplus
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}
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#endif
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#endif /* RDBX_H */
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