/// <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 IEEE802_1x 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 version = br.ReadByte();
var type = br.ReadByte();
var bodyLength = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var payloadLength = Math.Min(bodyLength, (int)(count - br.BaseStream.Position));
packet = null;
switch (type)
{
case (byte)Types.EAPOL_KEY:
{
EapolKey payload;
if (EapolKey.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IEEE802_1x <EapolKey> {
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 IEEE802_1x <Generic> {
Payload = payload
};
}
packet.Version = version;
packet.Type = type;
packet.BodyLength = bodyLength;
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 IEEE802_1x 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 version = br.ReadByte();
var type = br.ReadByte();
var bodyLength = ByteOrder.NetworkToHostOrder(br.ReadUInt16());
var payloadLength = Math.Min(bodyLength, (int)(count - br.BaseStream.Position));
packet = null;
switch (type)
{
case (byte)Types.EAPOL_KEY:
{
EapolKey payload;
if (EapolKey.TryParse(
buffer,
index + (int)br.BaseStream.Position,
payloadLength,
out payload))
{
packet = new IEEE802_1x<EapolKey> { 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 IEEE802_1x<Generic> { Payload = payload };
}
packet.Version = version;
packet.Type = type;
packet.BodyLength = bodyLength;
return true;
}
}
}
catch (Exception)
{
packet = null;
return false;
}
}
/// <summary>
/// Checks whether the specified pairwise transit key is valid for the EAPoL key
/// </summary>
/// <param name="eapolKey">The EAPoL key to check against</param>
/// <param name="ptk">The pairwise transit key to check</param>
/// <returns>True if the key is valid, false if it is not</returns>
public static bool PtkIsValid(IEEE802_1x<EapolKey> eapolKey, byte[] ptk)
{
var tkip = (eapolKey.Payload.KeyInformation & 7) == 1;
bool isValid;
var MIC = eapolKey.Payload.MIC;
eapolKey.Payload.MIC = new byte[MIC.Length];
try
{
HMAC hmac;
var key = ptk.Take(16).ToArray();
if (tkip)
{
#if DOTNET5_4
throw new System.Exception("The current version of System.Security.Cryptography.Algorithms is missing HMACMD5.");
#else
hmac = new HMACMD5(key);
#endif
}
else
{
hmac = new HMACSHA1(key);
}
var computedHash = hmac.ComputeHash(eapolKey.ToArray());
isValid = computedHash.Take(16).SequenceEqual(MIC.Take(16));
}
finally
{
eapolKey.Payload.MIC = MIC;
}
return isValid;
}
