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Test and fix anti-replay functions

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This commit is contained in:
Manuel Pégourié-Gonnard
2014-09-24 11:13:44 +02:00
committed by Paul Bakker
parent 7a7e140d4e
commit 4956fd7437
5 changed files with 107 additions and 14 deletions
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26
library/ssl_tls.c
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@ -2697,10 +2697,12 @@ static int ssl_prepare_handshake_record( ssl_context *ssl )
/*
* DTLS anti-replay: RFC 6347 4.1.2.6
*
* - in_window_top is the highest record sequence number seen
* - the lsb of in_window is set iff in_window_top - 1 has been seen
* ...
* the msb of in_window is set iff in_window_top - 64 has been seen
* in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
* Bit n is set iff record number in_window_top - n has been seen.
*
* Usually, in_window_top is the last record number seen and the lsb of
* in_window is set. The only exception is the initial state (record number 0
* not seen yet).
*/
#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
static void ssl_dtls_replay_reset( ssl_context *ssl )
@ -2730,10 +2732,7 @@ int ssl_dtls_replay_check( ssl_context *ssl )
if( rec_seqnum > ssl->in_window_top )
return( 0 );
if( rec_seqnum == ssl->in_window_top )
return( -1 );
bit = ssl->in_window_top - rec_seqnum - 1;
bit = ssl->in_window_top - rec_seqnum;
if( bit >= 64 )
return( -1 );
@ -2757,20 +2756,19 @@ void ssl_dtls_replay_update( ssl_context *ssl )
uint64_t shift = rec_seqnum - ssl->in_window_top;
if( shift >= 64 )
ssl->in_window = 0;
ssl->in_window = 1;
else
{
ssl->in_window <<= shift;
ssl->in_window |= 1;
}
ssl->in_window_top = rec_seqnum;
}
else if( rec_seqnum == ssl->in_window_top )
{
; /* Can't happen, but anyway, nothing to do if it happened */
}
else
{
/* Mark that number as seen in the current window */
uint64_t bit = ssl->in_window_top - rec_seqnum - 1;
uint64_t bit = ssl->in_window_top - rec_seqnum;
if( bit < 64 ) /* Always true, but be extra sure */
ssl->in_window |= (uint64_t) 1 << bit;