feature: Adding apipa nic support for swiftv2 windows

cni/network/invoker_cns.go

@@ -192,6 +192,11 @@ func (invoker *CNSIPAMInvoker) Add(addConfig IPAMAddConfig) (IPAMAddResult, erro
 			if err := addBackendNICToResult(&info, &addResult, key); err != nil {
 				return IPAMAddResult{}, err
 			}
+		case cns.ApipaNIC:
+			if err := configureApipaAddResult(&info, &addResult, &response.PodIPInfo[i].PodIPConfig, key); err != nil {
+				return IPAMAddResult{}, err
+			}
+
 		case cns.InfraNIC, "":
 			// if we change from legacy cns, the nicType will be empty, so we assume it is infra nic
 			info.nicType = cns.InfraNIC
@@ -508,6 +513,29 @@ func configureSecondaryAddResult(info *IPResultInfo, addResult *IPAMAddResult, p
 	return nil
 }
 
+func configureApipaAddResult(info *IPResultInfo, addResult *IPAMAddResult, podIPConfig *cns.IPSubnet, key string) error {
+	ip, ipnet, err := podIPConfig.GetIPNet()
+	if ip == nil {
+		return errors.Wrap(err, "Unable to parse IP from response: "+info.podIPAddress+" with err %w")
+	}
+
+	addResult.interfaceInfo[key] = network.InterfaceInfo{
+		IPConfigs: []*network.IPConfig{
+			{
+				Address: net.IPNet{
+					IP:   ip,
+					Mask: ipnet.Mask,
+				},
+				Gateway: net.ParseIP(info.ncGatewayIPAddress),
+			},
+		},
+		NICType:           info.nicType,
+		SkipDefaultRoutes: true,
+	}
+
+	return nil
+}
+
 func addBackendNICToResult(info *IPResultInfo, addResult *IPAMAddResult, key string) error {
 	macAddress, err := net.ParseMAC(info.macAddress)
 	if err != nil {

cns/NetworkContainerContract.go

@@ -93,6 +93,9 @@ const (
 	NodeNetworkInterfaceFrontendNIC NICType = "FrontendNIC"
 	// NodeNetworkInterfaceBackendNIC is the new name for BackendNIC
 	NodeNetworkInterfaceBackendNIC NICType = "BackendNIC"
+
+	// ApipaNIC is used for internal communication between host and container
+	ApipaNIC NICType = "ApipaNIC"
 )
 
 // ChannelMode :- CNS channel modes
@@ -516,6 +519,10 @@ type PodIpInfo struct {
 	PnPID string
 	// Default Deny ACL's to configure on HNS endpoints for Swiftv2 window nodes
 	EndpointPolicies []policy.Policy
+	// This flag is in effect only if nic type is apipa. This allows connection originating from host to container via apipa nic and not other way.
+	AllowHostToNCCommunication bool
+	// This flag is in effect only if nic type is apipa. This allows connection originating from container to host via apipa nic and not other way.
+	AllowNCToHostCommunication bool
 }
 
 type HostIPInfo struct {

cns/restserver/ipam.go

@@ -149,6 +149,7 @@ func (service *HTTPRestService) requestIPConfigHandlerHelperStandalone(ctx conte
 
 	// assign NICType and MAC Address for SwiftV2. we assume that there won't be any SwiftV1 NCs here
 	podIPInfoList := make([]cns.PodIpInfo, 0, len(resp))
+	apipaIndex := -1
 	for i := range resp {
 		podIPInfo := cns.PodIpInfo{
 			PodIPConfig:                     resp[i].IPConfiguration.IPSubnet,
@@ -157,6 +158,21 @@ func (service *HTTPRestService) requestIPConfigHandlerHelperStandalone(ctx conte
 			NetworkContainerPrimaryIPConfig: resp[i].IPConfiguration,
 		}
 		podIPInfoList = append(podIPInfoList, podIPInfo)
+		if resp[i].AllowHostToNCCommunication || resp[i].AllowNCToHostCommunication {
+			apipaIndex = i
+		}
+	}
+
+	if apipaIndex != -1 {
+		apipaPodIPInfo := cns.PodIpInfo{
+			PodIPConfig:                     resp[apipaIndex].LocalIPConfiguration.IPSubnet,
+			NICType:                         cns.ApipaNIC,
+			NetworkContainerPrimaryIPConfig: resp[apipaIndex].LocalIPConfiguration,
+			SkipDefaultRoutes:               true,
+			AllowHostToNCCommunication:      resp[apipaIndex].AllowHostToNCCommunication,
+			AllowNCToHostCommunication:      resp[apipaIndex].AllowNCToHostCommunication,
+		}
+		podIPInfoList = append(podIPInfoList, apipaPodIPInfo)
 	}
 
 	ipConfigsResp := &cns.IPConfigsResponse{

network/network_windows.go

@@ -342,7 +342,8 @@ func (nm *networkManager) addIPv6DefaultRoute() error {
 // newNetworkImplHnsV2 creates a new container network for HNSv2.
 func (nm *networkManager) newNetworkImplHnsV2(nwInfo *EndpointInfo, extIf *externalInterface) (*network, error) {
 	// network creation is not required for IB
-	if nwInfo.NICType == cns.BackendNIC {
+	// For apipa nic, we create network as part of endpoint creation
+	if nwInfo.NICType == cns.BackendNIC || nwInfo.NICType == cns.ApipaNIC {
 		return &network{Endpoints: make(map[string]*endpoint)}, nil
 	}