protected override void Decode(IChannelHandlerContext context, IByteBuffer input, List <object> output)
{
if (!this.suppressRead && !this.handshakeFailed)
{
int writerIndex = input.WriterIndex;
Exception error = null;
try
{
bool continueLoop = true;
for (int i = 0; i < MAX_SSL_RECORDS && continueLoop; i++)
{
int readerIndex = input.ReaderIndex;
int readableBytes = writerIndex - readerIndex;
if (readableBytes < TlsUtils.SSL_RECORD_HEADER_LENGTH)
{
// Not enough data to determine the record type and length.
return;
}
int command = input.GetByte(readerIndex);
// tls, but not handshake command
switch (command)
{
case TlsUtils.SSL_CONTENT_TYPE_CHANGE_CIPHER_SPEC:
case TlsUtils.SSL_CONTENT_TYPE_ALERT:
int len = TlsUtils.GetEncryptedPacketLength(input, readerIndex);
// Not an SSL/TLS packet
if (len == TlsUtils.NOT_ENCRYPTED)
{
this.handshakeFailed = true;
var e = new NotSslRecordException(
"not an SSL/TLS record: " + ByteBufferUtil.HexDump(input));
input.SkipBytes(input.ReadableBytes);
TlsUtils.NotifyHandshakeFailure(context, e);
throw e;
}
if (len == TlsUtils.NOT_ENOUGH_DATA ||
writerIndex - readerIndex - TlsUtils.SSL_RECORD_HEADER_LENGTH < len)
{
// Not enough data
return;
}
// increase readerIndex and try again.
input.SkipBytes(len);
continue;
case TlsUtils.SSL_CONTENT_TYPE_HANDSHAKE:
int majorVersion = input.GetByte(readerIndex + 1);
// SSLv3 or TLS
if (majorVersion == 3)
{
int packetLength = input.GetUnsignedShort(readerIndex + 3) + TlsUtils.SSL_RECORD_HEADER_LENGTH;
if (readableBytes < packetLength)
{
// client hello incomplete; try again to decode once more data is ready.
return;
}
// See https://tools.ietf.org/html/rfc5246#section-7.4.1.2
//
// Decode the ssl client hello packet.
// We have to skip bytes until SessionID (which sum to 43 bytes).
//
// struct {
// ProtocolVersion client_version;
// Random random;
// SessionID session_id;
// CipherSuite cipher_suites<2..2^16-2>;
// CompressionMethod compression_methods<1..2^8-1>;
// select (extensions_present) {
// case false:
// struct {};
// case true:
// Extension extensions<0..2^16-1>;
// };
// } ClientHello;
//
int endOffset = readerIndex + packetLength;
int offset = readerIndex + 43;
if (endOffset - offset < 6)
{
continueLoop = false;
break;
}
int sessionIdLength = input.GetByte(offset);
offset += sessionIdLength + 1;
int cipherSuitesLength = input.GetUnsignedShort(offset);
offset += cipherSuitesLength + 2;
int compressionMethodLength = input.GetByte(offset);
offset += compressionMethodLength + 1;
int extensionsLength = input.GetUnsignedShort(offset);
offset += 2;
int extensionsLimit = offset + extensionsLength;
if (extensionsLimit > endOffset)
{
// Extensions should never exceed the record boundary.
continueLoop = false;
break;
}
for (;;)
{
if (extensionsLimit - offset < 4)
{
continueLoop = false;
break;
}
int extensionType = input.GetUnsignedShort(offset);
offset += 2;
int extensionLength = input.GetUnsignedShort(offset);
offset += 2;
if (extensionsLimit - offset < extensionLength)
{
continueLoop = false;
break;
}
// SNI
// See https://tools.ietf.org/html/rfc6066#page-6
if (extensionType == 0)
{
offset += 2;
if (extensionsLimit - offset < 3)
{
continueLoop = false;
break;
}
int serverNameType = input.GetByte(offset);
offset++;
if (serverNameType == 0)
{
int serverNameLength = input.GetUnsignedShort(offset);
offset += 2;
if (serverNameLength <= 0 || extensionsLimit - offset < serverNameLength)
{
continueLoop = false;
break;
}
string hostname = input.ToString(offset, serverNameLength, Encoding.UTF8);
//try
//{
// select(ctx, IDN.toASCII(hostname,
// IDN.ALLOW_UNASSIGNED).toLowerCase(Locale.US));
//}
//catch (Throwable t)
//{
// PlatformDependent.throwException(t);
//}
var idn = new IdnMapping()
{
AllowUnassigned = true
};
hostname = idn.GetAscii(hostname);
#if NETSTANDARD1_3
// TODO: netcore does not have culture sensitive tolower()
hostname = hostname.ToLowerInvariant();
#else
hostname = hostname.ToLower(new CultureInfo("en-US"));
#endif
this.Select(context, hostname);
return;
}
else
{
// invalid enum value
continueLoop = false;
break;
}
}
offset += extensionLength;
}
}
break;
// Fall-through
default:
//not tls, ssl or application data, do not try sni
continueLoop = false;
break;
}
}
}
catch (Exception e)
{
error = e;
// unexpected encoding, ignore sni and use default
//if (//Logger.DebugEnabled)
//{
// //Logger.Warn($"Unexpected client hello packet: {ByteBufferUtil.HexDump(input)}", e);
//}
}
if (this.serverTlsSniSettings.DefaultServerHostName != null)
{
// Just select the default server TLS setting
this.Select(context, this.serverTlsSniSettings.DefaultServerHostName);
}
else
{
this.handshakeFailed = true;
var e = new DecoderException($"failed to get the server TLS setting {error}");
TlsUtils.NotifyHandshakeFailure(context, e);
throw e;
}
}
}
protected override void Decode(IChannelHandlerContext context, IByteBuffer input, List <object> output)
{
if (!_suppressRead && !_handshakeFailed)
{
Exception error = null;
try
{
int readerIndex = input.ReaderIndex;
int readableBytes = input.ReadableBytes;
int handshakeLength = -1;
// Check if we have enough data to determine the record type and length.
while (readableBytes >= TlsUtils.SSL_RECORD_HEADER_LENGTH)
{
int contentType = input.GetByte(readerIndex);
// tls, but not handshake command
switch (contentType)
{
case TlsUtils.SSL_CONTENT_TYPE_CHANGE_CIPHER_SPEC:
// fall-through
case TlsUtils.SSL_CONTENT_TYPE_ALERT:
int len = TlsUtils.GetEncryptedPacketLength(input, readerIndex);
// Not an SSL/TLS packet
if (len == TlsUtils.NOT_ENCRYPTED)
{
_handshakeFailed = true;
var e = new NotSslRecordException(
"not an SSL/TLS record: " + ByteBufferUtil.HexDump(input));
_ = input.SkipBytes(input.ReadableBytes);
_ = context.FireUserEventTriggered(new SniCompletionEvent(e));
TlsUtils.NotifyHandshakeFailure(context, e, true);
throw e;
}
if (len == TlsUtils.NOT_ENOUGH_DATA)
{
// Not enough data
return;
}
// SNI can't be present in an ALERT or CHANGE_CIPHER_SPEC record, so we'll fall back and
// assume no SNI is present. Let's let the actual TLS implementation sort this out.
// Just select the default SslContext
goto SelectDefault;
case TlsUtils.SSL_CONTENT_TYPE_HANDSHAKE:
int majorVersion = input.GetByte(readerIndex + 1);
// SSLv3 or TLS
if (majorVersion == 3)
{
int packetLength = input.GetUnsignedShort(readerIndex + 3) + TlsUtils.SSL_RECORD_HEADER_LENGTH;
if (readableBytes < packetLength)
{
// client hello incomplete; try again to decode once more data is ready.
return;
}
else if (packetLength == TlsUtils.SSL_RECORD_HEADER_LENGTH)
{
goto SelectDefault;
}
int endOffset = readerIndex + packetLength;
// Let's check if we already parsed the handshake length or not.
if (handshakeLength == -1)
{
if (readerIndex + 4 > endOffset)
{
// Need more data to read HandshakeType and handshakeLength (4 bytes)
return;
}
int handshakeType = input.GetByte(readerIndex + TlsUtils.SSL_RECORD_HEADER_LENGTH);
// Check if this is a clientHello(1)
// See https://tools.ietf.org/html/rfc5246#section-7.4
if (handshakeType != 1)
{
goto SelectDefault;
}
// Read the length of the handshake as it may arrive in fragments
// See https://tools.ietf.org/html/rfc5246#section-7.4
handshakeLength = input.GetUnsignedMedium(readerIndex + TlsUtils.SSL_RECORD_HEADER_LENGTH + 1);
// Consume handshakeType and handshakeLength (this sums up as 4 bytes)
readerIndex += 4;
packetLength -= 4;
if (handshakeLength + 4 + TlsUtils.SSL_RECORD_HEADER_LENGTH <= packetLength)
{
// We have everything we need in one packet.
// Skip the record header
readerIndex += TlsUtils.SSL_RECORD_HEADER_LENGTH;
Select(context, ExtractSniHostname(input, readerIndex, readerIndex + handshakeLength));
return;
}
else
{
if (_handshakeBuffer is null)
{
_handshakeBuffer = context.Allocator.Buffer(handshakeLength);
}
else
{
// Clear the buffer so we can aggregate into it again.
_ = _handshakeBuffer.Clear();
}
}
}
// Combine the encapsulated data in one buffer but not include the SSL_RECORD_HEADER
_ = _handshakeBuffer.WriteBytes(input, readerIndex + TlsUtils.SSL_RECORD_HEADER_LENGTH,
packetLength - TlsUtils.SSL_RECORD_HEADER_LENGTH);
readerIndex += packetLength;
readableBytes -= packetLength;
if (handshakeLength <= _handshakeBuffer.ReadableBytes)
{
Select(context, ExtractSniHostname(_handshakeBuffer, 0, handshakeLength));
return;
}
}
break;
default:
//not tls, ssl or application data, do not try sni
break;
}
}
}
catch (Exception e)
{
error = e;
// unexpected encoding, ignore sni and use default
if (Logger.WarnEnabled)
{
Logger.UnexpectedClientHelloPacket(input, e);
}
}
SelectDefault:
if (_serverTlsSniSettings.DefaultServerHostName is object)
{
// Just select the default server TLS setting
Select(context, _serverTlsSniSettings.DefaultServerHostName);
}
else
{
ReleaseHandshakeBuffer();
_handshakeFailed = true;
var e = new DecoderException($"failed to get the server TLS setting {error}");
TlsUtils.NotifyHandshakeFailure(context, e, true);
throw e;
}
}
}