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89 lines
2.8 KiB
89 lines
2.8 KiB
8 months ago
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#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.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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* </p>
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*/
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internal sealed class DtlsReplayWindow
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{
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private const long ValidSeqMask = 0x0000FFFFFFFFFFFFL;
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private const long WindowSize = 64L;
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private long m_latestConfirmedSeq = -1;
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private ulong m_bitmap = 0;
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/// <summary>Check whether a received record with the given sequence number should be rejected as a duplicate.
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/// </summary>
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/// <param name="seq">the 48-bit DTLSPlainText.sequence_number field of a received record.</param>
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/// <returns>true if the record should be discarded without further processing.</returns>
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internal bool ShouldDiscard(long seq)
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{
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if ((seq & ValidSeqMask) != seq)
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return true;
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if (seq <= m_latestConfirmedSeq)
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{
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long diff = m_latestConfirmedSeq - seq;
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if (diff >= WindowSize)
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return true;
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if ((m_bitmap & (1UL << (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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/// <summary>Report that a received record with the given sequence number passed authentication checks.
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/// </summary>
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/// <param name="seq">the 48-bit DTLSPlainText.sequence_number field of an authenticated record.</param>
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internal void ReportAuthenticated(long seq)
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{
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if ((seq & ValidSeqMask) != seq)
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throw new ArgumentException("out of range", "seq");
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if (seq <= m_latestConfirmedSeq)
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{
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long diff = m_latestConfirmedSeq - seq;
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if (diff < WindowSize)
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{
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m_bitmap |= (1UL << (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 - m_latestConfirmedSeq;
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if (diff >= WindowSize)
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{
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m_bitmap = 1;
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}
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else
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{
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m_bitmap <<= (int)diff; // for earlier JDKs
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m_bitmap |= 1UL;
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}
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m_latestConfirmedSeq = seq;
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}
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}
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internal void Reset(long seq)
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{
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if ((seq & ValidSeqMask) != seq)
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throw new ArgumentException("out of range", "seq");
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// Discard future records unless sequence number > 'seq'
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m_latestConfirmedSeq = seq;
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m_bitmap = ulong.MaxValue >> (int)System.Math.Max(0, 63 - seq);
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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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