blob: a08114c2acb604228cfeac7ca00a611ab77bf732 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
using System;
namespace Org.BouncyCastle.Tls
{
/**
* RFC 4347 4.1.2.5 Anti-replay
* <p>
* Support fast rejection of duplicate records by maintaining a sliding receive window
* </p>
*/
internal sealed class DtlsReplayWindow
{
private const long ValidSeqMask = 0x0000FFFFFFFFFFFFL;
private const long WindowSize = 64L;
private long m_latestConfirmedSeq = -1;
private ulong m_bitmap = 0;
/// <summary>Check whether a received record with the given sequence number should be rejected as a duplicate.
/// </summary>
/// <param name="seq">the 48-bit DTLSPlainText.sequence_number field of a received record.</param>
/// <returns>true if the record should be discarded without further processing.</returns>
internal bool ShouldDiscard(long seq)
{
if ((seq & ValidSeqMask) != seq)
return true;
if (seq <= m_latestConfirmedSeq)
{
long diff = m_latestConfirmedSeq - seq;
if (diff >= WindowSize)
return true;
if ((m_bitmap & (1UL << (int)diff)) != 0)
return true;
}
return false;
}
/// <summary>Report that a received record with the given sequence number passed authentication checks.
/// </summary>
/// <param name="seq">the 48-bit DTLSPlainText.sequence_number field of an authenticated record.</param>
internal void ReportAuthenticated(long seq)
{
if ((seq & ValidSeqMask) != seq)
throw new ArgumentException("out of range", "seq");
if (seq <= m_latestConfirmedSeq)
{
long diff = m_latestConfirmedSeq - seq;
if (diff < WindowSize)
{
m_bitmap |= (1UL << (int)diff);
}
}
else
{
long diff = seq - m_latestConfirmedSeq;
if (diff >= WindowSize)
{
m_bitmap = 1;
}
else
{
m_bitmap <<= (int)diff; // for earlier JDKs
m_bitmap |= 1UL;
}
m_latestConfirmedSeq = seq;
}
}
internal void Reset(long seq)
{
if ((seq & ValidSeqMask) != seq)
throw new ArgumentException("out of range", "seq");
// Discard future records unless sequence number > 'seq'
m_latestConfirmedSeq = seq;
m_bitmap = ulong.MaxValue >> (int)System.Math.Max(0, 63 - seq);
}
}
}
|
