private byte[] CreateRequest()
{
var request = new byte[24];
request[0] = 1; // packet type - request
request[1] = 1; // version number - v1
// bytes [2,3] are left empty
// bytes [4,5] are address family, since we want the whole routing table, leave empty
// bytes [6,7] are left empty
OwnIP.GetAddressBytes().CopyTo(request, 8); // so routers can identify each other by ip, since
//we are running on loopback
//next eight bytes are left empty
//following 4 bytes are metric, since max hop count is 15, set it to infinity(16)
BitConverter.GetBytes(MaxHopCount + 1).CopyTo(request, 20);
return(request);
}
private byte[] CreateResponse()
{
var responseHeader = new byte[24];
responseHeader[0] = 2; // packet type - response
responseHeader[1] = 1; // version number - v1
// next 2 bytes are left empty
// bytes [4,5] are address family
responseHeader[5] = 2; //ip address family is represented by 2
// next 2 bytes are left empty
OwnIP.GetAddressBytes().CopyTo(responseHeader, 8); // so routers can identify each other by ip, since
//we are running on loopback
//next eight bytes are left empty
//following 4 bytes are metric, since the router is a neighbor, cost is 0
//BitConverter.GetBytes(0).CopyTo(responseHeader, 20);
//every entry in routing table takes up 20 bytes
var response = new byte[responseHeader.Length + (RouteTable.Count * 20)];
responseHeader.CopyTo(response, 0);
var currentIndex = responseHeader.Length;
RouteTable.mutex.WaitOne();
foreach (var entry in RouteTable)
{
//first 2 bytes are address family
//ip address family is represented by 2
response[currentIndex + 1] = 2;
// next 2 bytes are left empty
// then 4 bytes are ip address of entry
BitConverter.GetBytes(ConvertToNetworkOrder(entry.Ip)).CopyTo(response, currentIndex + 4);
//next 8 bytes are left empty
//then 4 bytes are metric
BitConverter.GetBytes(ConvertToNetworkOrder(entry.Cost)).CopyTo(response, currentIndex + 16);
currentIndex += 20;
}
RouteTable.mutex.ReleaseMutex();
return(response);
}
public void PrintRoutingTable()
{
Console.WriteLine($"Router: {OwnIP.ToString()} Route entries: {RouteTable.Count}");
RouteTable.PrintItems();
}
