/// <summary>
/// Correct fields such as checksums. Recursive.
/// </summary>
public void CorrectFields()
{
this.Checksum = 0;
var thisAsBytes = this.ToArray();
this.Checksum = IPv4.ComputeChecksum(thisAsBytes, 0, thisAsBytes.Length);
}
/// <summary>
/// Attempts to parse raw data into a structured packet
/// </summary>
/// <param name="buffer">Raw data to parse</param>
/// <param name="packet">Parsed packet</param>
/// <param name="count">The length of the packet in bytes</param>
/// <param name="index">The index into the buffer at which the packet begins</param>
/// <returns>True if parsing was successful, false if it is not.</returns>
internal static bool TryParse(byte[] buffer, int index, int count, out SNAP packet)
{
try
{
if (count < MinimumParseableBytes)
{
packet = null;
return(false);
}
using (var ms = new MemoryStream(buffer, index, count, false))
{
using (var br = new BinaryReader(ms))
{
var organizationCode = br.ReadBytes(3);
var etherType = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
packet = null;
if (organizationCode[0] == 0 && organizationCode[1] == 0 && organizationCode[2] == 0)
{
switch (etherType)
{
case (ushort)EtherTypes.IPv4:
{
IPv4 payload;
if (IPv4.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload))
{
packet = new SNAP <IPv4> {
Payload = payload
};
}
}
break;
case (ushort)EtherTypes.ARP:
{
ARP payload;
if (ARP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload))
{
packet = new SNAP <ARP> {
Payload = payload
};
}
}
break;
case (ushort)EtherTypes.EAPoLAN:
{
IEEE802_1x payload;
if (IEEE802_1x.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload))
{
packet = new SNAP <IEEE802_1x> {
Payload = payload
};
}
}
break;
}
}
if (packet == null)
{
Generic payload;
Generic.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload);
// This can never fail, so I'm not checking the output
packet = new SNAP <Generic> {
Payload = payload
};
}
packet.OrganizationCode = organizationCode;
packet.ProtocolID = etherType;
return(true);
}
}
}
catch (Exception)
{
packet = null;
return(false);
}
}
/// <summary>
/// Attempts to parse raw data into a structured packet
/// </summary>
/// <param name="buffer">Raw data to parse</param>
/// <param name="packet">Parsed packet</param>
/// <param name="count">The length of the packet in bytes</param>
/// <param name="index">The index into the buffer at which the packet begins</param>
/// <returns>True if parsing was successful, false if it is not.</returns>
internal static bool TryParse(byte[] buffer, int index, int count, out IPv4 packet)
{
try
{
if (count < MinimumParseableBytes)
{
packet = null;
return(false);
}
using (var ms = new MemoryStream(buffer, index, count, false))
{
using (var br = new BinaryReader(ms))
{
var versionAndHeaderLen = br.ReadByte();
var version = versionAndHeaderLen >> 4;
var headerLength = versionAndHeaderLen & 0x0F;
var differentiatedServices = br.ReadByte();
var totalLength = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var id = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var flagsAndFragOff = new BitVector32(ByteOrder.NetworkToHostOrder(br.ReadUInt16()));
var ttl = br.ReadByte();
var protocol = br.ReadByte();
var headerChecksum = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var sourceAddress = new IPv4Address(br.ReadBytes(4));
var destAddress = new IPv4Address(br.ReadBytes(4));
if (headerLength == 0 || (headerLength * 32 / 8 > count))
{
// Specified header length is larger than available bytes
packet = null;
return(false);
}
byte[] optionsAndPadding;
if (headerLength * 32 / 8 < br.BaseStream.Position)
{
optionsAndPadding = br.ReadBytes(headerLength * 32 / 8 - (int)br.BaseStream.Position);
}
else
{
optionsAndPadding = Array.Empty <byte>();
}
br.BaseStream.Seek(headerLength * 32 / 8, SeekOrigin.Begin);
// TODO: Accept option for IgnoreLength
int payloadLength;
if (true /*IgnoreLength*/)
{
payloadLength = count - (int)br.BaseStream.Position;
}
/*else
* {
* payloadLength = (totalLength - (headerLength * 32 / 8)
* }*/
packet = null;
switch (protocol)
{
case (byte)Protocols.UDP:
{
UDP payload;
if (UDP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IPv4 <UDP> {
Payload = payload
};
}
}
break;
case (byte)Protocols.ICMP:
{
ICMP payload;
if (ICMP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IPv4 <ICMP> {
Payload = payload
};
}
}
break;
case (byte)Protocols.TCP:
{
TCP payload;
if (TCP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IPv4 <TCP> {
Payload = payload
};
}
}
break;
}
if (packet == null)
{
Generic payload;
Generic.TryParse(buffer, index + (int)br.BaseStream.Position, payloadLength, out payload);
// This can never fail, so I'm not checking the output
packet = new IPv4 <Generic> {
Payload = payload
};
}
packet.Version = version;
packet.HeaderLength = headerLength;
packet.DifferentiatedServices = differentiatedServices;
packet.TotalLength = totalLength;
packet.ID = id;
packet.FlagsAndFragOff = flagsAndFragOff;
packet.TTL = ttl;
packet.Protocol = protocol;
packet.HeaderChecksum = headerChecksum;
packet.SourceAddress = sourceAddress;
packet.DestAddress = destAddress;
packet.OptionsAndPadding = optionsAndPadding;
return(true);
}
}
}
catch (Exception)
{
packet = null;
return(false);
}
}
/// <summary>
/// Attempts to parse raw data into a structured packet
/// </summary>
/// <param name="buffer">Raw data to parse</param>
/// <param name="packet">Parsed packet</param>
/// <param name="count">The length of the packet in bytes</param>
/// <param name="index">The index into the buffer at which the packet begins</param>
/// <returns>True if parsing was successful, false if it is not.</returns>
internal static bool TryParse(byte[] buffer, int index, int count, out IPv4 packet)
{
try
{
if (count < MinimumParseableBytes)
{
packet = null;
return false;
}
using (var ms = new MemoryStream(buffer, index, count, false))
{
using (var br = new BinaryReader(ms))
{
var versionAndHeaderLen = br.ReadByte();
var version = versionAndHeaderLen >> 4;
var headerLength = versionAndHeaderLen & 0x0F;
var differentiatedServices = br.ReadByte();
var totalLength = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var id = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var flagsAndFragOff = new BitVector32(ByteOrder.NetworkToHostOrder(br.ReadUInt16()));
var ttl = br.ReadByte();
var protocol = br.ReadByte();
var headerChecksum = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var sourceAddress = new IPv4Address(br.ReadBytes(4));
var destAddress = new IPv4Address(br.ReadBytes(4));
if (headerLength == 0 || (headerLength * 32 / 8 > count))
{
// Specified header length is larger than available bytes
packet = null;
return false;
}
byte[] optionsAndPadding;
if (headerLength * 32 / 8 < br.BaseStream.Position)
{
optionsAndPadding = br.ReadBytes(headerLength * 32 / 8 - (int)br.BaseStream.Position);
}
else
{
optionsAndPadding = Array.Empty<byte>();
}
br.BaseStream.Seek(headerLength * 32 / 8, SeekOrigin.Begin);
// TODO: Accept option for IgnoreLength
int payloadLength;
if (true /*IgnoreLength*/)
{
payloadLength = count - (int)br.BaseStream.Position;
}
/*else
{
payloadLength = (totalLength - (headerLength * 32 / 8)
}*/
packet = null;
switch (protocol)
{
case (byte)Protocols.UDP:
{
UDP payload;
if (UDP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IPv4<UDP> { Payload = payload };
}
}
break;
case (byte)Protocols.ICMP:
{
ICMP payload;
if (ICMP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IPv4<ICMP> { Payload = payload };
}
}
break;
// TODO: Add TCP when ported over
}
if (packet == null)
{
Generic payload;
Generic.TryParse(buffer, index + (int)br.BaseStream.Position, payloadLength, out payload);
// This can never fail, so I'm not checking the output
packet = new IPv4<Generic> { Payload = payload };
}
packet.Version = version;
packet.HeaderLength = headerLength;
packet.DifferentiatedServices = differentiatedServices;
packet.TotalLength = totalLength;
packet.ID = id;
packet.FlagsAndFragOff = flagsAndFragOff;
packet.TTL = ttl;
packet.Protocol = protocol;
packet.HeaderChecksum = headerChecksum;
packet.SourceAddress = sourceAddress;
packet.DestAddress = destAddress;
packet.OptionsAndPadding = optionsAndPadding;
return true;
}
}
}
catch (Exception)
{
packet = null;
return false;
}
}
/// <summary>
/// Attempts to parse raw data into a structured packet
/// </summary>
/// <param name="buffer">Raw data to parse</param>
/// <param name="packet">Parsed packet</param>
/// <param name="count">The length of the packet in bytes</param>
/// <param name="index">The index into the buffer at which the packet begins</param>
/// <returns>True if parsing was successful, false if it is not.</returns>
internal static bool TryParse(byte[] buffer, int index, int count, out EthernetII packet)
{
try
{
if (count < MinimumParseableBytes)
{
packet = null;
return(false);
}
using (var ms = new MemoryStream(buffer, index, count, false))
{
using (var br = new BinaryReader(ms))
{
var dstMac = br.ReadBytes(6);
var srcMac = br.ReadBytes(6);
var etherType = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
packet = null;
switch (etherType)
{
case (ushort)EtherTypes.IPv4:
{
IPv4 payload;
if (IPv4.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload))
{
packet = new EthernetII <IPv4> {
Payload = payload
};
}
}
break;
case (ushort)EtherTypes.ARP:
{
ARP payload;
if (ARP.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload))
{
packet = new EthernetII <ARP> {
Payload = payload
};
}
}
break;
}
if (packet == null)
{
Generic payload;
Generic.TryParse(
buffer,
index + (int)br.BaseStream.Position,
(int)(count - br.BaseStream.Position),
out payload);
// This can never fail, so I'm not checking the output
packet = new EthernetII <Generic> {
Payload = payload
};
}
packet.DstMac = dstMac;
packet.EtherType = etherType;
packet.SrcMac = srcMac;
return(true);
}
}
}
catch (Exception)
{
packet = null;
return(false);
}
}
