/// <summary>
/// Handler for processing an unrecognised chunk parameter.
/// </summary>
/// <param name="chunkParameter">The Type-Length-Value (TLV) formatted chunk that was
/// not recognised.</param>
/// <returns>True if further parameter parsing for this chunk should be stopped.
/// False to continue.</returns>
public bool GotUnrecognisedParameter(SctpTlvChunkParameter chunkParameter)
{
bool stop = false;
switch (chunkParameter.UnrecognisedAction)
{
case SctpUnrecognisedParameterActions.Stop:
stop = true;
break;
case SctpUnrecognisedParameterActions.StopAndReport:
stop = true;
UnrecognizedPeerParameters.Add(chunkParameter);
break;
case SctpUnrecognisedParameterActions.Skip:
break;
case SctpUnrecognisedParameterActions.SkipAndReport:
UnrecognizedPeerParameters.Add(chunkParameter);
break;
}
return(stop);
}
/// <summary>
/// Writes the optional and variable length parameters to a Type-Length-Value (TLV)
/// parameter list.
/// </summary>
/// <returns>A TLV parameter list holding the optional and variable length parameters.</returns>
private List <SctpTlvChunkParameter> GetVariableParameters()
{
List <SctpTlvChunkParameter> varParams = new List <SctpTlvChunkParameter>();
// Add the optional and variable length parameters as Type-Length-Value (TLV) formatted.
foreach (var address in Addresses)
{
ushort addrParamType = (ushort)(address.AddressFamily == AddressFamily.InterNetwork ?
SctpInitChunkParameterType.IPv4Address : SctpInitChunkParameterType.IPv6Address);
var addrParam = new SctpTlvChunkParameter(addrParamType, address.GetAddressBytes());
varParams.Add(addrParam);
}
if (CookiePreservative > 0)
{
varParams.Add(
new SctpTlvChunkParameter((ushort)SctpInitChunkParameterType.CookiePreservative,
NetConvert.GetBytes(CookiePreservative)
));
}
if (!string.IsNullOrEmpty(HostnameAddress))
{
varParams.Add(
new SctpTlvChunkParameter((ushort)SctpInitChunkParameterType.HostNameAddress,
Encoding.UTF8.GetBytes(HostnameAddress)
));
}
if (SupportedAddressTypes.Count > 0)
{
byte[] paramVal = new byte[SupportedAddressTypes.Count * 2];
int paramValPosn = 0;
foreach (var supAddr in SupportedAddressTypes)
{
NetConvert.ToBuffer((ushort)supAddr, paramVal, paramValPosn);
paramValPosn += 2;
}
varParams.Add(
new SctpTlvChunkParameter((ushort)SctpInitChunkParameterType.SupportedAddressTypes, paramVal));
}
if (StateCookie != null)
{
varParams.Add(
new SctpTlvChunkParameter((ushort)SctpInitChunkParameterType.StateCookie, StateCookie));
}
foreach (var unrecognised in UnrecognizedPeerParameters)
{
varParams.Add(
new SctpTlvChunkParameter((ushort)SctpInitChunkParameterType.UnrecognizedParameter, unrecognised.GetBytes()));
}
return(varParams);
}
/// <summary>
/// Chunks can optionally contain Type-Length-Value (TLV) parameters. This method
/// parses any variable length parameters from a chunk's value.
/// </summary>
/// <param name="buffer">The buffer holding the serialised chunk.</param>
/// <param name="posn">The position in the buffer to start parsing variable length
/// parameters from.</param>
/// <param name="length">The length of the TLV chunk parameters in the buffer.</param>
/// <returns>A list of chunk parameters. Can be empty.</returns>
public static IEnumerable <SctpTlvChunkParameter> GetParameters(byte[] buffer, int posn, int length)
{
int paramPosn = posn;
while (paramPosn < posn + length)
{
var chunkParam = SctpTlvChunkParameter.ParseTlvParameter(buffer, paramPosn);
yield return(chunkParam);
paramPosn += chunkParam.GetParameterLength(true);
}
}
/// <summary>
/// Parses an SCTP Type-Length-Value (TLV) chunk parameter from a buffer.
/// </summary>
/// <param name="buffer">The buffer holding the serialised TLV chunk parameter.</param>
/// <param name="posn">The position to start parsing at.</param>
/// <returns>An SCTP TLV chunk parameter instance.</returns>
public static SctpTlvChunkParameter ParseTlvParameter(byte[] buffer, int posn)
{
if (buffer.Length < posn + SCTP_PARAMETER_HEADER_LENGTH)
{
throw new ApplicationException("Buffer did not contain the minimum of bytes for an SCTP TLV chunk parameter.");
}
var tlvParam = new SctpTlvChunkParameter();
ushort paramLen = tlvParam.ParseFirstWord(buffer, posn);
if (paramLen > SCTP_PARAMETER_HEADER_LENGTH)
{
tlvParam.ParameterValue = new byte[paramLen - SCTP_PARAMETER_HEADER_LENGTH];
Buffer.BlockCopy(buffer, posn + SCTP_PARAMETER_HEADER_LENGTH, tlvParam.ParameterValue,
0, tlvParam.ParameterValue.Length);
}
return(tlvParam);
}
