90 lines
2.6 KiB
C#
90 lines
2.6 KiB
C#
#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
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#pragma warning disable
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using System;
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namespace BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Tls
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{
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/**
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* RFC 4347 4.1.2.5 Anti-replay
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* <p/>
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* Support fast rejection of duplicate records by maintaining a sliding receive window
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*/
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internal class DtlsReplayWindow
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{
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private const long VALID_SEQ_MASK = 0x0000FFFFFFFFFFFFL;
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private const long WINDOW_SIZE = 64L;
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private long mLatestConfirmedSeq = -1;
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private long mBitmap = 0;
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/**
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* Check whether a received record with the given sequence number should be rejected as a duplicate.
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*
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* @param seq the 48-bit DTLSPlainText.sequence_number field of a received record.
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* @return true if the record should be discarded without further processing.
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*/
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internal bool ShouldDiscard(long seq)
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{
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if ((seq & VALID_SEQ_MASK) != seq)
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return true;
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if (seq <= mLatestConfirmedSeq)
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{
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long diff = mLatestConfirmedSeq - seq;
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if (diff >= WINDOW_SIZE)
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return true;
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if ((mBitmap & (1L << (int)diff)) != 0)
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return true;
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}
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return false;
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}
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/**
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* Report that a received record with the given sequence number passed authentication checks.
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*
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* @param seq the 48-bit DTLSPlainText.sequence_number field of an authenticated record.
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*/
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internal void ReportAuthenticated(long seq)
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{
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if ((seq & VALID_SEQ_MASK) != seq)
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throw new ArgumentException("out of range", "seq");
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if (seq <= mLatestConfirmedSeq)
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{
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long diff = mLatestConfirmedSeq - seq;
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if (diff < WINDOW_SIZE)
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{
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mBitmap |= (1L << (int)diff);
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}
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}
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else
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{
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long diff = seq - mLatestConfirmedSeq;
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if (diff >= WINDOW_SIZE)
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{
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mBitmap = 1;
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}
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else
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{
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mBitmap <<= (int)diff;
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mBitmap |= 1;
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}
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mLatestConfirmedSeq = seq;
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}
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}
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/**
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* When a new epoch begins, sequence numbers begin again at 0
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*/
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internal void Reset()
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{
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mLatestConfirmedSeq = -1;
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mBitmap = 0;
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}
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}
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}
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#pragma warning restore
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#endif
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