/// <summary>
/// Removes an entry from the route forwarding table.
/// </summary>
/// <param name="remoteNetworkAddr">Address of the route to delete</param>
/// <param name="remoteNetworkMask">Mask of the route to delete</param>
/// <returns>0 if successful, or error code if not.</returns>
public static int DeleteRoute(string remoteNetworkAddr, string remoteNetworkMask)
{
IPAddress addr, mask;
try { addr = IPAddress.Parse(remoteNetworkAddr); }
catch (Exception ex) { throw new ArgumentException("remoteNetworkAddr", ex); }
try { mask = IPAddress.Parse(remoteNetworkMask); }
catch (Exception ex) { throw new ArgumentException("remoteNetworkMask", ex); }
addr = ApplyMask(addr, mask); // make sure zero bits of the mask are zero in the address.
// Load the existing route table
NativeMethods.IpForwardRow[] rows = NativeMethods.GetIpForwardTable();
if (rows == null)
{
return((int)NativeMethods.IPErrorCodes.ERROR_FAILURE); // should never happen
}
// Find the address in the route table
foreach (NativeMethods.IpForwardRow row in rows)
{
if ((IPAddressAsUint(addr) == row.dwForwardDest) && (IPAddressAsUint(mask) == row.dwForwardMask))
{
// found, so delete it.
NativeMethods.IpForwardRow foundRow = row;
return(NativeMethods.DeleteIpForwardEntry(ref foundRow));
}
}
// if we got this far, the specified route was not in the table.
return((int)(NativeMethods.IPErrorCodes.ERROR_NOT_FOUND));
}
/// <summary>
/// Adds the specified route to the routine table
/// </summary>
/// <param name="remoteNetworkAddr"></param>
/// <param name="remoteNetworkMask"></param>
/// <param name="remoteNetworkGateway"></param>
/// <exception cref="ArgumentException">Thrown if arguments are not valid Internet address strings</exception>
/// <returns>0 if success, or error code if failed.</returns>
public static int AddRoute(string remoteNetworkAddr, string remoteNetworkMask, string remoteNetworkGateway)
{
int result;
IPAddress addr, mask, gate;
try { addr = IPAddress.Parse(remoteNetworkAddr); }
catch (Exception ex) { throw new ArgumentException("remoteNetworkAddr", ex); }
try { mask = IPAddress.Parse(remoteNetworkMask); }
catch (Exception ex) { throw new ArgumentException("remoteNetworkMask", ex); }
try { gate = IPAddress.Parse(remoteNetworkGateway); }
catch (Exception ex) { throw new ArgumentException("remoteNetworkGateway", ex); }
addr = ApplyMask(addr, mask); // make sure zero bits of the mask are zero in the address.
// figure out which adapter out of the list is the best to use
uint bestAdapterIndex = 0;
result = NativeMethods.GetBestInterface(IPAddressAsUint(gate), out bestAdapterIndex);
if (result != 0)
{
return(result);
}
// Load the existing route table
NativeMethods.IpForwardRow[] rows = NativeMethods.GetIpForwardTable();
if (rows == null)
{
return((int)NativeMethods.IPErrorCodes.ERROR_FAILURE); // should never happen
}
// Make sure the address isn't already covered in the route table
foreach (NativeMethods.IpForwardRow row in rows)
{
if ((row.dwForwardMask != 0) && ((IPAddressAsUint(addr) & row.dwForwardMask) == row.dwForwardDest))
{
return((int)NativeMethods.IPErrorCodes.ERROR_ALREADY_EXISTS);
}
}
// for some versions of Windows, the value of Metric1 must be greater than or equal to
// the value of the adapter metric. Unfortunately, it is somewhat difficult to get this value.
// We will work around this by duplicating the metric of any other route that uses this adapter,
// or, if none exist, use the maximum value of any route in the table. If the table is empty, we
// will use a fixed value of 255, and hope it works ok.
uint dwMetric = 0;
foreach (NativeMethods.IpForwardRow row in rows)
{
uint rowIndex = row.dwForwardIfIndex;
uint rowMetric = row.dwForwardMetric1;
if (rowIndex == bestAdapterIndex)
{
dwMetric = rowMetric;
break;
}
else if (rowMetric > dwMetric)
{
dwMetric = rowMetric;
}
}
// if we didn't find anything relevant, use 255 - this should be OK
dwMetric = (dwMetric == 0) ? 255 : dwMetric;
// Everything looks good - create the route.
NativeMethods.IpForwardRow newRoute = new NativeMethods.IpForwardRow();
newRoute.dwForwardDest = IPAddressAsUint(addr);
newRoute.dwForwardMask = IPAddressAsUint(mask);
newRoute.dwForwardPolicy = 0; // policy - always ;
newRoute.dwForwardNextHop = IPAddressAsUint(gate);
newRoute.dwForwardIfIndex = bestAdapterIndex;
newRoute.ForwardType = NativeMethods.IpForwardType.MIB_IPROUTE_TYPE_INDIRECT;
newRoute.ForwardProto = NativeMethods.IpForwardProto.MIB_IPPROTO_NETMGMT;
newRoute.dwForwardAge = 0;
newRoute.dwForwardNextHopAS = 0;
newRoute.dwForwardMetric1 = dwMetric;
newRoute.dwForwardMetric2 = 0;
newRoute.dwForwardMetric3 = 0;
newRoute.dwForwardMetric4 = 0;
newRoute.dwForwardMetric5 = 0;
return(NativeMethods.CreateIpForwardEntry(ref newRoute));
}
