/// <summary>
/// Performs and/or continues the authentication cycle.
/// </summary>
/// <param name="clientToken">The most recent token from the client.</param>
/// <returns>The client's next authentication token in the cycle.</returns>
/// <exception cref="ArgumentNullException"><paramref name="clientToken" /> is null.</exception>
/// <exception cref="SspiException">
/// This method was called after this context was fully initialized.
/// <para>or</para>
/// The underlying SSPI operation failed.
/// </exception>
/// <remarks>
/// This method is performed iteratively to start, continue, and end the authentication cycle with the server.
/// Each stage works by acquiring a token from one side and presenting it to the other side, which in turn may generate a new token.
/// The cycle continues until the client and server both indicate that they are done.
/// </remarks>
public SspiToken AcceptToken(SspiToken clientToken)
{
if (clientToken == null)
{
throw new ArgumentNullException(nameof(clientToken));
}
if (Disposed)
{
throw new ObjectDisposedException(nameof(SecurityContext));
}
else if (Initialized)
{
throw new SspiException("Attempted to call Initialize on a server context that was already initialized.");
}
SecureBuffer clientBuffer = new SecureBuffer(clientToken.Token, SecureBufferType.Token);
SecureBuffer outputBuffer = new SecureBuffer(new byte[Credential.PackageInfo.MaxTokenLength], SecureBufferType.Token);
SecurityStatus status = Handle.AcceptSecurityContext(outputBuffer, clientBuffer, Credential.Handle, _requestedAttributes);
if (!status.IsError())
{
if (status == SecurityStatus.Ok)
{
Initialized = true;
}
return(new SspiToken(outputBuffer));
}
else
{
throw new SspiException("Failed to initialize security context for a server.");
}
}