UdpSendStatus SendFragmentedMessage(UdpRawMessage message, IChannel channel)
{
message.Position = 0;
int mtu = this.Mtu;
ushort frame = 1;
ushort frames = (ushort)Math.Ceiling(message.Length / (float)(mtu - Datagram.GetHeaderSize(true)));
ushort groupId = GetNextFragementationGroupId();
do
{
Debug.Assert(frame <= frames, "frame > frames");
Datagram datagramFrag = Datagram.CreateNew(peer.Configuration.MemoryStreamPool, mtu);
datagramFrag.Type = MessageType.UserData;
datagramFrag.Channel = channel.Descriptor.Channel;
datagramFrag.DeliveryType = channel.Descriptor.DeliveryType;
datagramFrag.FragmentationInfo = new Datagram.FragmentInfo(groupId, frame, frames);
datagramFrag.ConnectionKey = this.EndPoint.ConnectionKey;
int toCopy = mtu - Datagram.GetHeaderSize(true);
if (toCopy > message.Length - message.Position)
{
toCopy = message.Length - message.Position;
}
message.CopyTo(datagramFrag.BaseStream, toCopy);
channel.SendDatagram(datagramFrag);
frame++;
} while (message.Position < message.Length);
message.Dispose();
return(UdpSendStatus.Enqueued);
}
bool CheckCanBeSendUnfragmented(UdpRawMessage datagram)
{
if (datagram.Length + Datagram.GetHeaderSize(false) > Mtu)
{
return(false);
}
return(true);
}
void SendNextMtuExpand()
{
int nextMtu = 0;
if (smallestFailedMtu < 0)
{
nextMtu = (int)(this.Mtu * 1.25);
}
else
{
nextMtu = (int)(((float)smallestFailedMtu + (float)Mtu) / 2.0f);
}
if (nextMtu > peer.Configuration.LimitMtu)
{
nextMtu = peer.Configuration.LimitMtu;
}
if (nextMtu == Mtu)
{
FixMtu();
return;
}
lastMtuExpandSent = DateTime.UtcNow;
int size = nextMtu - Datagram.GetHeaderSize(false);
var mtuDatagram = CreateSpecialDatagram(MessageType.ExpandMTURequest, size);
mtuDatagram.BaseStream.SetLength(size);
if (mtuDatagram.GetTotalSize() != nextMtu)
{
throw new Exception("Datagram total size doesn't match header+body size. Perhaps header size calculation failed");
}
logger.Debug($"Expanding MTU to {nextMtu}");
SendDatagramAsync(mtuDatagram).ContinueWith(t => {
if (t.Result != System.Net.Sockets.SocketError.Success)
{
logger.Debug($"MTU {nextMtu} expand send failed with {t.Result}");
if (smallestFailedMtu < 1 || nextMtu < smallestFailedMtu)
{
smallestFailedMtu = nextMtu;
mtuFailedAttempts++;
if (mtuFailedAttempts >= peer.Configuration.MtuExpandMaxFailAttempts)
{
FixMtu();
return;
}
SendNextMtuExpand();
}
}
}, TaskContinuationOptions.OnlyOnRanToCompletion);
}