public IpV4Packet Defrag(
IpV4Packet ipPacket
)
{
var result = ipPacket;
var header = ipPacket.Header;
if (header.IsFragmented)
{
var ufid = ipPacket.Header.UniqueFragmentId;
var agent = CreateOrGetAgent(ufid);
result = agent.Consume(ipPacket);
if (result != null)
{
agentMap_.Remove(ufid);
}
}
return(result);
}
public IpV4Packet Consume(
IpV4Packet packet
)
{
IpV4Packet mergedPacket = null;
if (packet == null)
{
throw new ArgumentNullException("packet");
}
var header = packet.Header;
var isNotFragmented = false;
var offsetInterval = default(IntervalInt32);
switch (header.FragmentFlags)
{
case 0x00:
if (header.FragmentOffset > 0)
{
if (lastFragmentHeader_ != null)
{
throw new Exception("Duplicated last fragment!");
}
lastFragmentHeader_ = packet.Header;
offsetInterval = new IntervalInt32(header.FragmentOffset, holeList_.Range.Maximum);
}
else
{
isNotFragmented = true;
}
break;
case 0x01:
if (header.FragmentOffset == 0)
{
if (firstFragmentHeader_ != null)
{
throw new Exception("Duplicated first fragment!");
}
else
{
firstFragmentHeader_ = packet.Header;
}
}
if ((header.PayloadLength & ((1 << 3) - 1)) != 0)
{
throw new FormatException("The length of non-final fragments must be multiple of 8.");
}
offsetInterval = new IntervalInt32(header.FragmentOffset, (header.PayloadLength > 0 ? header.PayloadLength - 1 : 0));
break;
case 0x02:
isNotFragmented = true;
break;
default:
throw new FormatException("The fragment flag has an invalid value.");
}
if (isNotFragmented)
{
mergedPacket = packet;
Reset();
}
else
{
try {
holeList_.Fill(offsetInterval);
payloadMap_.Add(header.FragmentOffset, packet.Payload);
if (holeList_.HasNoMoreHoles)
{
if (lastFragmentHeader_ == null || firstFragmentHeader_ == null)
{
throw new FormatException("");
}
var mergedPayloadLength = lastFragmentHeader_.FragmentOffset + lastFragmentHeader_.PayloadLength;
var mergedPayloadBuffer = new ByteBuffer(lastFragmentHeader_.FragmentOffset + lastFragmentHeader_.PayloadLength);
foreach (var pair in payloadMap_)
{
mergedPayloadBuffer.Enqueue(pair.Value);
}
if (mergedPayloadBuffer.Count != mergedPayloadLength)
{
throw new FormatException("");
}
mergedPacket = new IpV4Packet(header, mergedPayloadBuffer.Dequeue());
Reset();
}
}
catch (Exception e) {
Reset();
throw e;
}
}
return(mergedPacket);
}
