Revert "change apipa network gw address from .1 to .2 (#2933)"

This reverts commit 7d6ce69.

Author: jackieluc

cns/hnsclient/hnsclient_windows.go

@@ -17,7 +17,6 @@ import (
 	"github.com/pkg/errors"
 )
 
-// TODO redesign hnsclient on windows
 const (
 	// Name of the external hns network
 	ExtHnsNetworkName = "ext"
@@ -53,9 +52,6 @@ const (
 	// Name of the loopback adapter needed to create Host NC apipa network
 	hostNCLoopbackAdapterName = "LoopbackAdapterHostNCConnectivity"
 
-	// HNS rehydration issue requires this GW to be different than the loopback adapter ip, so we set it to .2
-	defaultHnsGwIPAddress       = "169.254.128.2"
-	hnsLoopbackAdapterIPAddress = "169.254.128.1"
 	// protocolTCP indicates the TCP protocol identifier in HCN
 	protocolTCP = "6"
 
@@ -304,7 +300,7 @@ func createHostNCApipaNetwork(
 		if interfaceExists, _ := networkcontainers.InterfaceExists(hostNCLoopbackAdapterName); !interfaceExists {
 			ipconfig := cns.IPConfiguration{
 				IPSubnet: cns.IPSubnet{
-					IPAddress:    hnsLoopbackAdapterIPAddress,
+					IPAddress:    localIPConfiguration.GatewayIPAddress,
 					PrefixLength: localIPConfiguration.IPSubnet.PrefixLength,
 				},
 				GatewayIPAddress: localIPConfiguration.GatewayIPAddress,
@@ -513,7 +509,7 @@ func configureHostNCApipaEndpoint(
 	endpointPolicies, err := configureAclSettingHostNCApipaEndpoint(
 		protocolList,
 		networkContainerApipaIP,
-		hnsLoopbackAdapterIPAddress,
+		hostApipaIP,
 		allowNCToHostCommunication,
 		allowHostToNCCommunication,
 		ncPolicies)
@@ -576,7 +572,6 @@ func CreateHostNCApipaEndpoint(
 		return endpoint.Id, nil
 	}
 
-	updateGwForLocalIPConfiguration(&localIPConfiguration)
 	if network, err = createHostNCApipaNetwork(localIPConfiguration); err != nil {
 		logger.Errorf("[Azure CNS] Failed to create HostNCApipaNetwork. Error: %v", err)
 		return "", err
@@ -608,17 +603,6 @@ func CreateHostNCApipaEndpoint(
 	return endpoint.Id, nil
 }
 
-// updateGwForLocalIPConfiguration applies change on gw IP address for apipa NW and endpoint.
-// Currently, cns using the same ip address "169.254.128.1" for both apipa gw and loopback adapter. This cause conflict issue when hns get restarted and not able to rehydrate the apipa endpoints.
-// This func is to overwrite the address to 169.254.128.2 when the gateway address is 169.254.128.1
-func updateGwForLocalIPConfiguration(localIPConfiguration *cns.IPConfiguration) {
-	// When gw address is 169.254.128.1, should use .2 instead. If gw address is not .1, that mean this value is
-	// configured from dnc, we should keep it
-	if localIPConfiguration.GatewayIPAddress == "169.254.128.1" {
-		localIPConfiguration.GatewayIPAddress = defaultHnsGwIPAddress
-	}
-}
-
 func getHostNCApipaEndpointName(
 	networkContainerID string) string {
 	return hostNCApipaEndpointNamePrefix + "-" + networkContainerID