public virtual void ProcessServerExtensions(IDictionary serverExtensions)
{
/*
* TlsProtocol implementation validates that any server extensions received correspond to
* client extensions sent. By default, we don't send any, and this method is not called.
*/
if (serverExtensions != null)
{
/*
* RFC 5246 7.4.1.4.1. Servers MUST NOT send this extension.
*/
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.signature_algorithms);
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.supported_groups);
if (TlsEccUtilities.IsEccCipherSuite(this.mSelectedCipherSuite))
{
this.mServerECPointFormats = TlsEccUtilities.GetSupportedPointFormatsExtension(serverExtensions);
}
else
{
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.ec_point_formats);
}
/*
* RFC 7685 3. The server MUST NOT echo the extension.
*/
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.padding);
}
}
public virtual void ProcessServerExtensions(IDictionary serverExtensions)
{
/*
* TlsProtocol implementation validates that any server extensions received correspond to
* client extensions sent. By default, we don't send any, and this method is not called.
*/
if (serverExtensions != null)
{
/*
* RFC 5246 7.4.1.4.1. Servers MUST NOT send this extension.
*/
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.signature_algorithms);
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.supported_groups);
if (TlsEccUtilities.IsEccCipherSuite(this.mSelectedCipherSuite))
{
this.mServerECPointFormats = TlsEccUtilities.GetSupportedPointFormatsExtension(serverExtensions);
}
else
{
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.ec_point_formats);
}
/*
* RFC 7685 3. The server MUST NOT echo the extension.
*/
CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.padding);
// https://tools.ietf.org/html/rfc7301
byte[] extensionData = TlsUtilities.GetExtensionData(serverExtensions, ExtensionType.application_layer_protocol_negotiation);
if (extensionData != null)
{
using (var exBuf = new MemoryStream(extensionData, false))
{
byte[] alpnList = TlsUtilities.ReadOpaque16(exBuf);
// the "ProtocolNameList" MUST contain exactly one "ProtocolName"
using (var alpnBuf = new MemoryStream(alpnList)) {
byte[] asciiBytes = TlsUtilities.ReadOpaque8(alpnBuf);
this.ServerSupportedProtocol = Strings.FromAsciiByteArray(asciiBytes);
}
}
}
}
}
public virtual void ProcessClientExtensions(IDictionary clientExtensions)
{
this.mClientExtensions = clientExtensions;
if (clientExtensions != null)
{
this.mEncryptThenMacOffered = TlsExtensionsUtilities.HasEncryptThenMacExtension(clientExtensions);
this.mMaxFragmentLengthOffered = TlsExtensionsUtilities.GetMaxFragmentLengthExtension(clientExtensions);
if (mMaxFragmentLengthOffered >= 0 && !MaxFragmentLength.IsValid((byte)mMaxFragmentLengthOffered))
{
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
this.mTruncatedHMacOffered = TlsExtensionsUtilities.HasTruncatedHMacExtension(clientExtensions);
this.mSupportedSignatureAlgorithms = TlsUtilities.GetSignatureAlgorithmsExtension(clientExtensions);
if (this.mSupportedSignatureAlgorithms != null)
{
/*
* RFC 5246 7.4.1.4.1. Note: this extension is not meaningful for TLS versions prior
* to 1.2. Clients MUST NOT offer it if they are offering prior versions.
*/
if (!TlsUtilities.IsSignatureAlgorithmsExtensionAllowed(mClientVersion))
{
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
}
this.mNamedCurves = TlsEccUtilities.GetSupportedEllipticCurvesExtension(clientExtensions);
this.mClientECPointFormats = TlsEccUtilities.GetSupportedPointFormatsExtension(clientExtensions);
}
/*
* RFC 4429 4. The client MUST NOT include these extensions in the ClientHello message if it
* does not propose any ECC cipher suites.
*
* NOTE: This was overly strict as there may be ECC cipher suites that we don't recognize.
* Also, draft-ietf-tls-negotiated-ff-dhe will be overloading the 'elliptic_curves'
* extension to explicitly allow FFDHE (i.e. non-ECC) groups.
*/
//if (!this.mEccCipherSuitesOffered && (this.mNamedCurves != null || this.mClientECPointFormats != null))
// throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
