private static async Task <byte[]> GetLengthBytes(BufferStreamAsyncDelegate sourceStreamReader, CancellationToken cancellationToken)
{
var lengthBytes = new List <byte>();
var firstLengthByte = await sourceStreamReader(1, cancellationToken);
lengthBytes.AddRange(firstLengthByte);
var lengthByteValue = firstLengthByte[0] & LengthBitMask;
if (lengthByteValue <= 125)
{
return(lengthBytes.ToArray());
}
switch (lengthByteValue)
{
case 126:
{
var secondLengthBytes = await sourceStreamReader(2, cancellationToken);
lengthBytes.AddRange(secondLengthBytes);
return(lengthBytes.ToArray());
}
case 127:
{
var secondLengthBytes = await sourceStreamReader(8, cancellationToken);
lengthBytes.AddRange(secondLengthBytes);
return(lengthBytes.ToArray());
}
default:
throw new Exception($"Unexpected first length byte value: {lengthByteValue}");
}
}
private static async Task ListenForMessages(BufferStreamAsyncDelegate sourceStreamReader,
WriteStreamAsyncDelegate destinationStreamWriter,
CancellationToken cancellationToken)
{
var messageBuilder = new List <byte>();
var firstByte = await sourceStreamReader(1, cancellationToken);
messageBuilder.AddRange(firstByte);
var lengthBytes = await GetLengthBytes(sourceStreamReader, cancellationToken);
messageBuilder.AddRange(lengthBytes);
var isMaskBitSet = (lengthBytes[0] & MaskBitMask) != 0;
var length = GetMessageLength(lengthBytes);
if (isMaskBitSet)
{
var maskBytes = await sourceStreamReader(4, cancellationToken);
messageBuilder.AddRange(maskBytes);
}
var messagePayloadBytes = await sourceStreamReader(length, cancellationToken);
messageBuilder.AddRange(messagePayloadBytes);
await destinationStreamWriter(messageBuilder.ToArray(), 0, messageBuilder.Count, cancellationToken);
}
