/// <summary>
/// Analyse the frame header, calculate RTO.
/// </summary>
/// <param name="fh_message">The fh_message.</param>
/// <param name="reload_connection">The reload_connection.</param>
/// <returns></returns>
private byte[] analyseFrameHeader(SimpleOverlayConnectionTableElement connectionTableEntry, byte[] fh_message) {
if (ReloadGlobals.Framing) {
/* Handle FrameHeader */
FramedMessageType type = (FramedMessageType)fh_message[0];
if (type == FramedMessageType.ack) {
FramedMessageAck fh_ack = FMA_FromBytes(fh_message);
m_ReloadConfig.Logger(ReloadGlobals.TRACEFLAGS.T_FH, String.Format("Rx FH ACK {0}, 0x{1:x}", fh_ack.ack_sequence, fh_ack.received));
/* Calculate RTO */
DateTime sent;
if (connectionTableEntry.fh_sent.TryGetValue(fh_ack.ack_sequence, out sent)) {
long rtt = DateTime.Now.Ticks - sent.Ticks;
if (connectionTableEntry.srtt == 0.0) {
connectionTableEntry.srtt = rtt;
connectionTableEntry.rttvar = 0.5 * rtt;
connectionTableEntry.rto = new TimeSpan(Convert.ToInt64(rtt + 4 * connectionTableEntry.rttvar));
}
else {
double alpha = 0.125;
double beta = 0.25;
connectionTableEntry.srtt = (1.0 - alpha) * connectionTableEntry.srtt + alpha * rtt;
connectionTableEntry.rttvar = (1.0 - beta) * connectionTableEntry.rttvar + beta * System.Math.Abs(connectionTableEntry.srtt - rtt);
connectionTableEntry.rto = new TimeSpan(Convert.ToInt64(connectionTableEntry.srtt + 4 * connectionTableEntry.rttvar));
}
connectionTableEntry.fh_sent.Remove(fh_ack.ack_sequence);
m_ReloadConfig.Logger(ReloadGlobals.TRACEFLAGS.T_FH, String.Format("RTT {0}, SRTT {1}, RTTVAR {2}, RTO {3}", rtt, connectionTableEntry.srtt, connectionTableEntry.rttvar, connectionTableEntry.rto));
}
}
else {
if (type == FramedMessageType.data) {
FramedMessageData fh_data = FMD_FromBytes(fh_message);
byte[] fh_stripped_data = new byte[fh_message.Length - 8];
Array.Copy(fh_message, 8, fh_stripped_data, 0, fh_message.Length - 8);
UInt32 received = 0;
UInt32 n = fh_data.sequence;
/* Calculate FH received mask */
foreach (UInt32 m in connectionTableEntry.fh_received) {
if (m < n || m >= (n - 32)) {
UInt32 bit = n - m - 1;
if (bit < 32)
received |= ((UInt32)1 << (int)bit);
}
}
while (connectionTableEntry.fh_received.Count >= 32)
connectionTableEntry.fh_received.Dequeue();
connectionTableEntry.fh_received.Enqueue(fh_data.sequence);
/* Acknowledge it */
FramedMessageAck fh_ack = new FramedMessageAck();
fh_ack.type = FramedMessageType.ack;
fh_ack.ack_sequence = fh_data.sequence;
fh_ack.received = received;
m_ReloadConfig.Logger(ReloadGlobals.TRACEFLAGS.T_FH, String.Format("Tx FH ACK {0}, 0x{1:x}", fh_ack.ack_sequence, fh_ack.received));
//in - offset out - bytesprocessed
Send(new Node(connectionTableEntry.NodeID, null), ToBytes(fh_ack));
return fh_stripped_data;
}
}
return null;
}
else
return fh_message;
}
public byte[] ToBytes(FramedMessageAck fmack) {
MemoryStream ms = new MemoryStream();
using (BinaryWriter writer = new BinaryWriter(ms)) {
writer.Write((Byte)fmack.type);
writer.Write(System.Net.IPAddress.HostToNetworkOrder((int)fmack.ack_sequence));
writer.Write(System.Net.IPAddress.HostToNetworkOrder((int)fmack.received));
}
return ms.ToArray();
}
