Fix routing between containers on same host

main.go

@@ -150,13 +150,13 @@ func getMyceliumIP(interfaceName string) (net.IP, error) {
 func generateContainerIP(myceliumPrefix net.IP, containerID string) net.IP {
 	// Generate a unique container IP within the /64 prefix using container ID hash
 	hash := sha256.Sum256([]byte(containerID))
-	
+
 	containerIP := make(net.IP, len(myceliumPrefix))
 	copy(containerIP, myceliumPrefix)
-	
+
 	// Use first 8 bytes of hash for the host part (last 64 bits)
 	copy(containerIP[8:], hash[:8])
-	
+
 	return containerIP
 }
 
@@ -259,8 +259,28 @@ func configureContainerInterface(containerNS netns.NsHandle, ifName string, cont
 	}
 
 	if hostLLAddr != nil {
-		// Add route to Mycelium network via host veth
+		// First remove any existing route to our /64
+		myceliumPrefix := &net.IPNet{
+			IP:   containerIP.Mask(net.CIDRMask(64, 128)),
+			Mask: net.CIDRMask(64, 128),
+		}
+		existingRoute := &netlink.Route{
+			Dst: myceliumPrefix,
+		}
+		netlink.RouteDel(existingRoute)
+
+		// Add route to our /64 via host veth
 		route := &netlink.Route{
+			Dst:       myceliumPrefix,
+			Gw:        hostLLAddr,
+			LinkIndex: link.Attrs().Index,
+		}
+		if err := netlink.RouteAdd(route); err != nil {
+			return err
+		}
+
+		// Add route to Mycelium network via host veth
+		route = &netlink.Route{
 			Dst: &net.IPNet{
 				IP:   net.ParseIP("400::"),
 				Mask: net.CIDRMask(7, 128),