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using System;
using System.Collections;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Tls
{
internal sealed class DtlsReassembler
{
private readonly short m_msg_type;
private readonly byte[] m_body;
private readonly IList m_missing = Platform.CreateArrayList();
internal DtlsReassembler(short msg_type, int length)
{
this.m_msg_type = msg_type;
this.m_body = new byte[length];
this.m_missing.Add(new Range(0, length));
}
internal short MsgType
{
get { return m_msg_type; }
}
internal byte[] GetBodyIfComplete()
{
return m_missing.Count > 0 ? null : m_body;
}
internal void ContributeFragment(short msg_type, int length, byte[] buf, int off, int fragment_offset,
int fragment_length)
{
int fragment_end = fragment_offset + fragment_length;
if (m_msg_type != msg_type || m_body.Length != length || fragment_end > length)
return;
if (fragment_length == 0)
{
// NOTE: Empty messages still require an empty fragment to complete it
if (fragment_offset == 0 && m_missing.Count > 0)
{
Range firstRange = (Range)m_missing[0];
if (firstRange.End == 0)
{
m_missing.RemoveAt(0);
}
}
return;
}
for (int i = 0; i < m_missing.Count; ++i)
{
Range range = (Range)m_missing[i];
if (range.Start >= fragment_end)
break;
if (range.End > fragment_offset)
{
int copyStart = System.Math.Max(range.Start, fragment_offset);
int copyEnd = System.Math.Min(range.End, fragment_end);
int copyLength = copyEnd - copyStart;
Array.Copy(buf, off + copyStart - fragment_offset, m_body, copyStart, copyLength);
if (copyStart == range.Start)
{
if (copyEnd == range.End)
{
m_missing.RemoveAt(i--);
}
else
{
range.Start = copyEnd;
}
}
else
{
if (copyEnd != range.End)
{
m_missing.Insert(++i, new Range(copyEnd, range.End));
}
range.End = copyStart;
}
}
}
}
internal void Reset()
{
m_missing.Clear();
m_missing.Add(new Range(0, m_body.Length));
}
private sealed class Range
{
private int m_start, m_end;
internal Range(int start, int end)
{
this.m_start = start;
this.m_end = end;
}
public int Start
{
get { return m_start; }
set { this.m_start = value; }
}
public int End
{
get { return m_end; }
set { this.m_end = value; }
}
}
}
}
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