/// <summary>
/// Converts bytes to <c>MPLSPackage</c>
/// </summary>
/// <param name="bytes">Received stream of bytes</param>
/// <returns>Converted package</returns>
/// <exception cref="InvalidMPLSPackageException">Thrown when a stream of bytes is not a valid package</exception>
public static MPLSPackage FromBytes(byte[] bytes)
{
try
{
MPLSPackage package = new MPLSPackage();
package.LabelStack = LabelStack.FromBytes(bytes);
var stackLength = package.LabelStack.GetLength();
package.ID = BitConverter.ToInt32(bytes, stackLength);
package.PacketLength = BitConverter.ToInt32(bytes, stackLength + 4);
package.TTL = (ushort)((bytes[stackLength + 9] << 8) + bytes[stackLength + 8]);
package.SourceAddress = new IPAddress(new byte[]
{ bytes[stackLength + 10], bytes[stackLength + 11], bytes[stackLength + 12], bytes[stackLength + 13] });
package.DestAddress = new IPAddress(new byte[]
{
bytes[stackLength + 14], bytes[stackLength + 15], bytes[stackLength + 16], bytes[stackLength + 17]
});
package.Port = (ushort)((bytes[stackLength + 19] << 8) + bytes[stackLength + 18]);
var usefulPayload = new List <byte>();
usefulPayload.AddRange(bytes.ToList()
.GetRange(stackLength + 20, package.PacketLength - HeaderLength));
package.Payload = Encoding.ASCII.GetString(usefulPayload.ToArray());
return(package);
}
catch (Exception)
{
throw new InvalidMPLSPackageException();
}
}
/// <summary>
/// Converts a stream of bytes to a valid LabelStack.
/// </summary>
/// <param name="bytes">A stream of bytes that will be converted.</param>
/// <returns>Valid label stack</returns>
public static LabelStack FromBytes(byte[] bytes)
{
LabelStack labelStack = new LabelStack();
if (bytes[0] == StackNotEmptyFlag)
{
var index = 1;
while (true)
{
var label = new Label
{
Number = (short)((bytes[index + 1] << 8) + bytes[index]),
TTL = bytes[index + 2]
};
var bottomOfStack = bytes[index + 3];
labelStack.Labels.Push(label);
if (bottomOfStack == 0xff)
{
break;
}
index = index + 4;
}
}
return(labelStack);
}
public static LabelStack returnToStack(byte [] bytes)
{
LabelStack my_Stack = new LabelStack();
int id = 1;
if (bytes[0] == stackNotEmpty) // look at flag
{
while (true)
{
Label label = new Label //construction of label: | label_Number 2 bytes | TTL 1 byte | INFO 1 byte |
{
labelNumber = (ushort)((bytes[id + 1] << 8) + bytes[id]),
TTL = bytes[id + 2]
};
my_Stack.labels.Push(label);
if (bytes[id + 3] == 0xff) // check the bottom of Stack
{
break;
}
id = id + 4; // size of label=4 bytes
}
}
return(my_Stack);
}
// package looks like : | length of label stack | message ID 1 BYTE | TTL 1 byte | Source Address 4 bytes | Dest Address 4 bytes | Port 2 bytes | CurrentNode 4 bytes| length of payload |
public static Package returnToPackage(byte[] bytes)
{
Package myPackage = new Package();
myPackage.labelStack = LabelStack.returnToStack(bytes);
var length_of_stack = myPackage.labelStack.GetLengthOfStack();
int headerLength = 24 + length_of_stack;
//myPackage.package_length = headerLength + myPackage.payload.Length;
myPackage.messageID = BitConverter.ToInt32(bytes, length_of_stack);
myPackage.package_length = BitConverter.ToInt32(bytes, length_of_stack + 4);
myPackage.TTL = (ushort)((bytes[length_of_stack + 9] << 8) + bytes[length_of_stack + 8]);
myPackage.SourceAddress = new IPAddress(new byte[] { bytes[length_of_stack + 10], bytes[length_of_stack + 11], bytes[length_of_stack + 12], bytes[length_of_stack + 13] });
myPackage.DestinationAddress = new IPAddress(new byte[] { bytes[length_of_stack + 14], bytes[length_of_stack + 15], bytes[length_of_stack + 16], bytes[length_of_stack + 17] });
myPackage.Port = (ushort)((bytes[length_of_stack + 19] << 8) + bytes[length_of_stack + 18]);
myPackage.CurrentNodeIP = new IPAddress(new byte[] { bytes[length_of_stack + 20], bytes[length_of_stack + 21], bytes[length_of_stack + 22], bytes[length_of_stack + 23] });
List <byte> listForPayload = new List <byte>();
listForPayload.AddRange(bytes.ToList()
.GetRange(length_of_stack + 24, myPackage.package_length - headerLength));
myPackage.payload = Encoding.ASCII.GetString(listForPayload.ToArray());
//Console.WriteLine("Your payload: " +myPackage.payload);
return(myPackage);
}
/// <summary>
/// Peeks a top label from <c>LabelStack</c> without popping it.
/// </summary>
/// <returns>Peeked top labeled or null, if <c>LabelStack</c> is empty</returns>
public Label PeekTopLabel()
{
if (LabelStack.IsEmpty())
{
return(null);
}
return(LabelStack.Labels.Peek());
}
/// <summary>
/// Generates a message to be shown by a host or node, after receiving/sending package.
/// </summary>
/// <returns>Generated string</returns>
public override string ToString()
{
if (LabelStack.IsEmpty())
{
return($"[ID={ID}, LabelStack={LabelStack}, Payload={Payload}, TTLStack={TTL}, Source={SourceAddress}, Destination={DestAddress}]");
}
else
{
var TTLStack = string.Join(", ", LabelStack.Labels.ToList().Select(label => label.TTL)) + ", " + TTL;
return($"[ID={ID}, LabelStack={LabelStack}, Payload={Payload}, TTLStack={TTLStack}, Source={SourceAddress}, Destination={DestAddress}]");
}
}
/// <summary>
/// Converts <c>MPLSPackage</c> to bytes
/// </summary>
/// <returns>Converted package</returns>
public byte[] ToBytes()
{
List <byte> result = new List <byte>();
PacketLength = HeaderLength + Payload.Length;
result.AddRange(LabelStack.GetBytes());
result.AddRange(BitConverter.GetBytes(ID));
result.AddRange(BitConverter.GetBytes(PacketLength));
result.AddRange(BitConverter.GetBytes(TTL));
result.AddRange(SourceAddress.GetAddressBytes());
result.AddRange(DestAddress.GetAddressBytes());
result.AddRange(BitConverter.GetBytes(Port));
result.AddRange(Encoding.ASCII.GetBytes(Payload ?? ""));
return(result.ToArray());
}
/// <summary>
/// Initalizes MPLS package and sets default value of TTL.
/// </summary>
public MPLSPackage()
{
LabelStack = new LabelStack();
TTL = DefaultTTL;
}
public Package()
{
labelStack = new LabelStack();
TTL = 255; // default value
}