/// <summary>
/// The Name Resolution Block is used to support the correlation of numeric addresses (present in the captured packets) and their
/// corresponding canonical names and it is optional. Having the literal names saved in the file, this prevents the need of a name
/// resolution in a delayed time, when the association between names and addresses can be different from the one in use at capture time.
/// Moreover, the Name Resolution Block avoids the need of issuing a lot of DNS requests every time the trace capture is opened,
/// and allows to have name resolution also when reading the capture with a machine not connected to the network.
/// A Name Resolution Block is normally placed at the beginning of the file, but no assumptions can be taken about its position.
/// Name Resolution Blocks can be added in a second time by tools that process the file, like network analyzers.
/// </summary>
public NameResolutionBlock(NameResolutionRecord nameResolutionRecords, NameResolutionOption Options, long PositionInStream = 0)
{
Contract.Requires <ArgumentNullException>(Options != null, "Options cannot be null");
Contract.Requires <ArgumentNullException>(nameResolutionRecords != null, "NameResolutionRecords cannot be null");
this.NameResolutionRecords = nameResolutionRecords;
this.options = Options;
this.PositionInStream = PositionInStream;
}
public static void NameResolutionBlock_ConvertToByte_Test(bool reorder)
{
byte[] option = { 1, 0, 12, 0, 84, 101, 115, 116, 32, 67, 111, 109, 109, 101, 110, 116, 2, 0, 8, 0, 68, 110, 115, 32, 78, 97, 109, 101, 3, 0, 4, 0, 127, 0, 0, 1, 4, 0, 16, 0, 32, 1, 13, 219, 0, 0, 0, 0, 0, 0, 0, 0, 20, 40, 87, 171, 0, 0, 0, 0 };
byte[] records = { 1, 0, 13, 0, 127, 0, 0, 1, 108, 111, 99, 97, 108, 104, 111, 115, 116, 0, 0, 0, 2, 0, 25, 0, 32, 1, 13, 219, 0, 0, 0, 0, 0, 0, 0, 0, 20, 40, 87, 171, 116, 101, 115, 116, 32, 97, 100, 100, 114, 0, 0, 0, 0, 0, 0, 0 };
NameResolutionBlock prePacketBlock, postPacketBlock;
using (MemoryStream optionStream = new MemoryStream(option))
{
using (MemoryStream recordsStream = new MemoryStream(records))
{
using (BinaryReader optionBinaryReader = new BinaryReader(optionStream))
{
using (BinaryReader recordsBinaryReader = new BinaryReader(recordsStream))
{
NameResolutionRecord rec = NameResolutionRecord.Parse(recordsBinaryReader, false, null);
Assert.IsNotNull(rec);
NameResolutionOption opt = NameResolutionOption.Parse(optionBinaryReader, false, null);
Assert.IsNotNull(opt);
prePacketBlock = new NameResolutionBlock(rec, opt, 0);
}
}
}
}
Assert.IsNotNull(prePacketBlock);
byte[] byteblock = prePacketBlock.ConvertToByte(reorder, null);
using (MemoryStream stream = new MemoryStream(byteblock))
{
using (BinaryReader binaryReader = new BinaryReader(stream))
{
AbstractBlock block = AbstractBlockFactory.ReadNextBlock(binaryReader, reorder, null);
Assert.IsNotNull(block);
postPacketBlock = block as NameResolutionBlock;
Assert.IsNotNull(postPacketBlock);
Assert.AreEqual(prePacketBlock.BlockType, postPacketBlock.BlockType);
Assert.AreEqual(prePacketBlock.NameResolutionRecords.Count, postPacketBlock.NameResolutionRecords.Count);
for (int i = 0; i < prePacketBlock.NameResolutionRecords.Count; i++)
{
Assert.AreEqual(prePacketBlock.NameResolutionRecords[i], postPacketBlock.NameResolutionRecords[i]);
}
Assert.AreEqual(prePacketBlock.Options.Comment, postPacketBlock.Options.Comment);
Assert.AreEqual(prePacketBlock.Options.DnsName, postPacketBlock.Options.DnsName);
Assert.AreEqual(prePacketBlock.Options.DnsIp4Addr, postPacketBlock.Options.DnsIp4Addr);
Assert.AreEqual(prePacketBlock.Options.DnsIp6Addr, postPacketBlock.Options.DnsIp6Addr);
}
}
}
public static NameResolutionBlock Parse(BaseBlock baseBlock, Action <Exception> ActionOnException)
{
Contract.Requires <ArgumentNullException>(baseBlock != null, "BaseBlock cannot be null");
Contract.Requires <ArgumentNullException>(baseBlock.Body != null, "BaseBlock.Body cannot be null");
Contract.Requires <ArgumentException>(baseBlock.BlockType == BaseBlock.Types.NameResolution, "Invalid packet type");
long positionInStream = baseBlock.PositionInStream;
using (Stream stream = new MemoryStream(baseBlock.Body))
{
using (BinaryReader binaryReader = new BinaryReader(stream))
{
NameResolutionRecord nameResolutionRecords = NameResolutionRecord.Parse(binaryReader, baseBlock.ReverseByteOrder, ActionOnException);
NameResolutionOption options = NameResolutionOption.Parse(binaryReader, baseBlock.ReverseByteOrder, ActionOnException);
NameResolutionBlock nameResolutionBlock = new NameResolutionBlock(nameResolutionRecords, options, positionInStream);
return(nameResolutionBlock);
}
}
}
