private async Task SendOpenSecureChannelRequestAsync(OpenSecureChannelRequest request, CancellationToken token)
{
var bodyStream = SerializableBytes.CreateWritableStream();
var bodyEncoder = new BinaryEncoder(bodyStream, this);
try
{
bodyEncoder.WriteNodeId(null, OpenSecureChannelRequestNodeId);
request.Encode(bodyEncoder);
bodyStream.Position = 0;
if (bodyStream.Length > this.RemoteMaxMessageSize)
{
throw new ServiceResultException(StatusCodes.BadEncodingLimitsExceeded);
}
// write chunks
int chunkCount = 0;
int bodyCount = (int)(bodyStream.Length - bodyStream.Position);
while (bodyCount > 0)
{
chunkCount++;
if (this.RemoteMaxChunkCount > 0 && chunkCount > this.RemoteMaxChunkCount)
{
throw new ServiceResultException(StatusCodes.BadEncodingLimitsExceeded);
}
var stream = new MemoryStream(this.sendBuffer, 0, (int)this.RemoteReceiveBufferSize, true, true);
var encoder = new BinaryEncoder(stream, this);
try
{
// header
encoder.WriteUInt32(null, UaTcpMessageTypes.OPNF);
encoder.WriteUInt32(null, 0u);
encoder.WriteUInt32(null, this.ChannelId);
// asymmetric security header
encoder.WriteString(null, this.RemoteEndpoint.SecurityPolicyUri);
if (this.RemoteEndpoint.SecurityMode != MessageSecurityMode.None)
{
encoder.WriteByteString(null, this.localCertificateBlob);
encoder.WriteByteString(null, this.RemoteCertificate.GetCertHash());
}
else
{
encoder.WriteByteString(null, null);
encoder.WriteByteString(null, null);
}
int plainHeaderSize = encoder.Position;
// sequence header
encoder.WriteUInt32(null, this.GetNextSequenceNumber());
encoder.WriteUInt32(null, request.RequestHeader.RequestHandle);
// body
int paddingHeaderSize;
int maxBodySize;
int bodySize;
int paddingSize;
int chunkSize;
if (this.asymIsEncrypted)
{
paddingHeaderSize = this.asymRemoteCipherTextBlockSize > 256 ? 2 : 1;
maxBodySize = ((((int)this.RemoteReceiveBufferSize - plainHeaderSize - this.asymLocalSignatureSize - paddingHeaderSize) / this.asymRemoteCipherTextBlockSize) * this.asymRemotePlainTextBlockSize) - SequenceHeaderSize;
if (bodyCount < maxBodySize)
{
bodySize = bodyCount;
paddingSize = (this.asymRemotePlainTextBlockSize - ((SequenceHeaderSize + bodySize + paddingHeaderSize + this.asymLocalSignatureSize) % this.asymRemotePlainTextBlockSize)) % this.asymRemotePlainTextBlockSize;
}
else
{
bodySize = maxBodySize;
paddingSize = 0;
}
chunkSize = plainHeaderSize + (((SequenceHeaderSize + bodySize + paddingSize + paddingHeaderSize + this.asymLocalSignatureSize) / this.asymRemotePlainTextBlockSize) * this.asymRemoteCipherTextBlockSize);
}
else
{
paddingHeaderSize = 0;
paddingSize = 0;
maxBodySize = (int)this.RemoteReceiveBufferSize - plainHeaderSize - this.asymLocalSignatureSize - SequenceHeaderSize;
if (bodyCount < maxBodySize)
{
bodySize = bodyCount;
}
else
{
bodySize = maxBodySize;
}
chunkSize = plainHeaderSize + SequenceHeaderSize + bodySize + this.asymLocalSignatureSize;
}
bodyStream.Read(this.sendBuffer, encoder.Position, bodySize);
encoder.Position += bodySize;
bodyCount -= bodySize;
// padding
if (this.asymIsEncrypted)
{
byte paddingByte = (byte)(paddingSize & 0xFF);
encoder.WriteByte(null, paddingByte);
for (int i = 0; i < paddingSize; i++)
{
encoder.WriteByte(null, paddingByte);
}
if (paddingHeaderSize == 2)
{
byte extraPaddingByte = (byte)((paddingSize >> 8) & 0xFF);
encoder.WriteByte(null, extraPaddingByte);
}
}
// update message type and (encrypted) length
var position = encoder.Position;
encoder.Position = 3;
encoder.WriteByte(null, bodyCount > 0 ? (byte)'C' : (byte)'F');
encoder.WriteUInt32(null, (uint)chunkSize);
encoder.Position = position;
// sign
if (this.asymIsSigned)
{
// sign with local private key.
byte[] signature = this.LocalPrivateKey.SignData(this.sendBuffer, 0, position, this.asymSignatureHashAlgorithmName, RSASignaturePadding.Pkcs1);
Debug.Assert(signature.Length == this.asymLocalSignatureSize, nameof(this.asymLocalSignatureSize));
encoder.Write(signature, 0, this.asymLocalSignatureSize);
}
// encrypt
if (this.asymIsEncrypted)
{
position = encoder.Position;
Buffer.BlockCopy(this.sendBuffer, 0, this.encryptionBuffer, 0, plainHeaderSize);
byte[] plainText = new byte[this.asymRemotePlainTextBlockSize];
int jj = plainHeaderSize;
for (int ii = plainHeaderSize; ii < position; ii += this.asymRemotePlainTextBlockSize)
{
Buffer.BlockCopy(this.sendBuffer, ii, plainText, 0, this.asymRemotePlainTextBlockSize);
// encrypt with remote public key.
byte[] cipherText = this.RemotePublicKey.Encrypt(plainText, this.asymEncryptionPadding);
Debug.Assert(cipherText.Length == this.asymRemoteCipherTextBlockSize, nameof(this.asymRemoteCipherTextBlockSize));
Buffer.BlockCopy(cipherText, 0, this.encryptionBuffer, jj, this.asymRemoteCipherTextBlockSize);
jj += this.asymRemoteCipherTextBlockSize;
}
await this.SendAsync(this.encryptionBuffer, 0, jj, token).ConfigureAwait(false);
return;
}
// pass buffer to transport
await this.SendAsync(this.sendBuffer, 0, encoder.Position, token).ConfigureAwait(false);
}
finally
{
encoder.Dispose();
}
}
}
finally
{
bodyEncoder.Dispose();
}
}
