/// <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 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);
}
}