/// <summary>
/// Computes the <see cref="RouteDistance" /> between the associated <see cref="MsgRouter" />
/// and a <see cref="LogicalRoute" />.
/// </summary>
/// <param name="logicalRoute">The first <see cref="LogicalRoute" />.</param>
/// <returns>The computed <see cref="RouteDistance" />.</returns>
internal RouteDistance ComputeDistance(LogicalRoute logicalRoute)
{
if (logicalRoute.Handlers != null)
{
return(RouteDistance.Process);
}
else if (router.RouterEP == null)
{
return(RouteDistance.Unknown);
}
MsgEP routerEP = router.RouterEP;
MsgEP targetEP = logicalRoute.PhysicalRoute.RouterEP;
PhysicalRoute physical = logicalRoute.PhysicalRoute;
int routerLevel = routerEP.Segments.Length;
int targetLevel = targetEP.Segments.Length;
bool sameIP = physical.TcpEP != null && router.TcpEP.Address.Equals(physical.TcpEP.NetEP.Address);
if (routerEP.IsPhysicalMatch(targetEP))
{
// The routes match so we're in the same process.
return(RouteDistance.Process);
}
if (routerLevel == targetLevel)
{
// The endpoints are at the same level in the heirarchy.
switch (routerLevel)
{
case 0:
// Both routers are at the root level
if (sameIP)
{
return(RouteDistance.Machine);
}
else
{
return(RouteDistance.Subnet);
}
case 1:
// Must be hub routers on different subnets
return(RouteDistance.External);
case 2:
// Both routes are to leaf routers.
if (routerEP.IsPhysicalPeer(targetEP))
{
if (sameIP)
{
return(RouteDistance.Machine);
}
else
{
return(RouteDistance.Subnet);
}
}
// If not peers, then they must be in different datacenters.
return(RouteDistance.External);
default:
throw new NotImplementedException();
}
}
// The endpoints are at different levels in the heirarchy. Normalize
// these so that higherEP and higherLevel specified the route target
// that is higher in the heirarchy and lowerEP and lowerLevel the
// target lower in the heirarchy.
MsgEP higherEP;
int higherLevel;
MsgEP lowerEP;
int lowerLevel;
if (routerLevel < targetLevel)
{
higherEP = routerEP;
higherLevel = routerLevel;
lowerEP = targetEP;
lowerLevel = targetLevel;
}
else
{
higherEP = targetEP;
higherLevel = targetLevel;
lowerEP = routerEP;
lowerLevel = routerLevel;
}
if (higherLevel == 1 && lowerLevel == 2 && higherEP.IsPhysicalDescendant(lowerEP))
{
// The higher level endpoint is on a hub and the lower level endpoint is
// on a router under the hub so they're on the same subnet.
return(RouteDistance.Subnet);
}
// All remaining cases will be considered to be external since
// they can't be on the same subnet.
return(RouteDistance.External);
}