public static async Task <Greeting> ReadFromAsync(IReadOnlyStream stream, ArrayPool <byte> bufferPool)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (bufferPool == null)
{
throw new ArgumentNullException(nameof(bufferPool));
}
// |VER | NMETHODS | METHODS |
// | 1 | 1 | 1 to 255 |
var buffer = bufferPool.Rent(256);
try
{
await stream.ReadExactlyAsync(buffer, 0, 3).ConfigureAwait(false);
if (buffer[0] != 5)
{
throw new InvalidDataException($"Invalid SOCKS version in greeting: {buffer[0]}");
}
var supportedAuthenticationMethodCount = buffer[1];
if (supportedAuthenticationMethodCount < 1)
{
throw new InvalidDataException("No authentication methods supported.");
}
var greeting = new Greeting
{
SupportedAuthenticationMethods = new AuthenticationMethod[supportedAuthenticationMethodCount]
};
greeting.SupportedAuthenticationMethods[0] = (AuthenticationMethod)buffer[2];
if (supportedAuthenticationMethodCount > 1)
{
stream.ReadExactly(buffer, 0, supportedAuthenticationMethodCount - 1);
for (int i = 0; i < supportedAuthenticationMethodCount - 1; i++)
{
greeting.SupportedAuthenticationMethods[i + 1] = (AuthenticationMethod)buffer[i];
}
}
return(greeting);
}
finally
{
bufferPool.Return(buffer);
}
}