private async Task ProcessSettingsFrameAsync()
{
if (_currentHeadersStream != null)
{
throw new Http2ConnectionErrorException(CoreStrings.FormatHttp2ErrorHeadersInterleaved(_incomingFrame.Type, _incomingFrame.StreamId, _currentHeadersStream.StreamId), Http2ErrorCode.PROTOCOL_ERROR);
}
if (_incomingFrame.StreamId != 0)
{
throw new Http2ConnectionErrorException(CoreStrings.FormatHttp2ErrorStreamIdNotZero(_incomingFrame.Type), Http2ErrorCode.PROTOCOL_ERROR);
}
if (_incomingFrame.SettingsAck)
{
if (_incomingFrame.PayloadLength != 0)
{
throw new Http2ConnectionErrorException(CoreStrings.Http2ErrorSettingsAckLengthNotZero, Http2ErrorCode.FRAME_SIZE_ERROR);
}
return;
}
if (_incomingFrame.PayloadLength % 6 != 0)
{
throw new Http2ConnectionErrorException(CoreStrings.Http2ErrorSettingsLengthNotMultipleOfSix, Http2ErrorCode.FRAME_SIZE_ERROR);
}
try
{
// int.MaxValue is the largest allowed windows size.
var previousInitialWindowSize = (int)_clientSettings.InitialWindowSize;
var previousMaxFrameSize = _clientSettings.MaxFrameSize;
_clientSettings.Update(_incomingFrame.GetSettings());
// Ack before we update the windows, they could send data immediately.
await _frameWriter.WriteSettingsAckAsync();
if (_clientSettings.MaxFrameSize != previousMaxFrameSize)
{
_frameWriter.UpdateMaxFrameSize(_clientSettings.MaxFrameSize);
}
// This difference can be negative.
var windowSizeDifference = (int)_clientSettings.InitialWindowSize - previousInitialWindowSize;
if (windowSizeDifference != 0)
{
foreach (var stream in _streams.Values)
{
if (!stream.TryUpdateOutputWindow(windowSizeDifference))
{
// This means that this caused a stream window to become larger than int.MaxValue.
// This can never happen with a well behaved client and MUST be treated as a connection error.
// https://httpwg.org/specs/rfc7540.html#rfc.section.6.9.2
throw new Http2ConnectionErrorException(CoreStrings.Http2ErrorInitialWindowSizeInvalid, Http2ErrorCode.FLOW_CONTROL_ERROR);
}
}
}
}
catch (Http2SettingsParameterOutOfRangeException ex)
{
throw new Http2ConnectionErrorException(CoreStrings.FormatHttp2ErrorSettingsParameterOutOfRange(ex.Parameter), ex.Parameter == Http2SettingsParameter.SETTINGS_INITIAL_WINDOW_SIZE
? Http2ErrorCode.FLOW_CONTROL_ERROR
: Http2ErrorCode.PROTOCOL_ERROR);
}
}