s/HostIP/HostIPv4/ for `com.docker.network.host_ipv4` setting

Rename all variables/fields/map keys associated with the
`com.docker.network.host_ipv4` option from `HostIP` to `HostIPv4`.
Rationale:

  * This makes the variable/field name consistent with the option
    name.
  * This makes the code more readable because it is clear that the
    variable/field does not hold an IPv6 address.  This will hopefully
    avoid bugs like <https://github.com/moby/moby/issues/46445> in the
    future.
  * If IPv6 SNAT support is ever added, the names will be symmetric.

Signed-off-by: Richard Hansen <rhansen@rhansen.org>

libnetwork/drivers/bridge/bridge_linux.go

@@ -73,7 +73,7 @@ type networkConfiguration struct {
 	Mtu                  int
 	DefaultBindingIP     net.IP
 	DefaultBridge        bool
-	HostIP               net.IP
+	HostIPv4             net.IP
 	ContainerIfacePrefix string
 	// Internal fields set after ipam data parsing
 	AddressIPv4        *net.IPNet
@@ -266,8 +266,8 @@ func (c *networkConfiguration) fromLabels(labels map[string]string) error {
 			}
 		case netlabel.ContainerIfacePrefix:
 			c.ContainerIfacePrefix = value
-		case netlabel.HostIP:
-			if c.HostIP = net.ParseIP(value); c.HostIP == nil {
+		case netlabel.HostIPv4:
+			if c.HostIPv4 = net.ParseIP(value); c.HostIPv4 == nil {
 				return parseErr(label, value, "nil ip")
 			}
 		}

libnetwork/drivers/bridge/bridge_linux_test.go

@@ -298,7 +298,7 @@ func TestCreateFullOptionsLabels(t *testing.T) {
 	}
 
 	bndIPs := "127.0.0.1"
-	testHostIP := "1.2.3.4"
+	testHostIPv4 := "1.2.3.4"
 	nwV6s := "2001:db8:2600:2700:2800::/80"
 	gwV6s := "2001:db8:2600:2700:2800::25/80"
 	nwV6, _ := types.ParseCIDR(nwV6s)
@@ -310,7 +310,7 @@ func TestCreateFullOptionsLabels(t *testing.T) {
 		EnableICC:          "true",
 		EnableIPMasquerade: "true",
 		DefaultBindingIP:   bndIPs,
-		netlabel.HostIP:    testHostIP,
+		netlabel.HostIPv4:  testHostIPv4,
 	}
 
 	netOption := make(map[string]interface{})
@@ -358,9 +358,9 @@ func TestCreateFullOptionsLabels(t *testing.T) {
 		t.Fatalf("Unexpected: %v", nw.config.DefaultBindingIP)
 	}
 
-	hostIP := net.ParseIP(testHostIP)
-	if !hostIP.Equal(nw.config.HostIP) {
-		t.Fatalf("Unexpected: %v", nw.config.HostIP)
+	hostIP := net.ParseIP(testHostIPv4)
+	if !hostIP.Equal(nw.config.HostIPv4) {
+		t.Fatalf("Unexpected: %v", nw.config.HostIPv4)
 	}
 
 	if !types.CompareIPNet(nw.config.AddressIPv6, nwV6) {

libnetwork/drivers/bridge/bridge_store.go

@@ -146,7 +146,8 @@ func (ncfg *networkConfiguration) MarshalJSON() ([]byte, error) {
 	nMap["Internal"] = ncfg.Internal
 	nMap["DefaultBridge"] = ncfg.DefaultBridge
 	nMap["DefaultBindingIP"] = ncfg.DefaultBindingIP.String()
-	nMap["HostIP"] = ncfg.HostIP.String()
+	// This key is "HostIP" instead of "HostIPv4" to preserve compatibility with the on-disk format.
+	nMap["HostIP"] = ncfg.HostIPv4.String()
 	nMap["DefaultGatewayIPv4"] = ncfg.DefaultGatewayIPv4.String()
 	nMap["DefaultGatewayIPv6"] = ncfg.DefaultGatewayIPv6.String()
 	nMap["ContainerIfacePrefix"] = ncfg.ContainerIfacePrefix
@@ -189,8 +190,9 @@ func (ncfg *networkConfiguration) UnmarshalJSON(b []byte) error {
 		ncfg.ContainerIfacePrefix = v.(string)
 	}
 
+	// This key is "HostIP" instead of "HostIPv4" to preserve compatibility with the on-disk format.
 	if v, ok := nMap["HostIP"]; ok {
-		ncfg.HostIP = net.ParseIP(v.(string))
+		ncfg.HostIPv4 = net.ParseIP(v.(string))
 	}
 
 	ncfg.DefaultBridge = nMap["DefaultBridge"].(bool)

libnetwork/drivers/bridge/setup_ip_tables_linux.go

@@ -249,9 +249,9 @@ func setupIPTablesInternal(ipVer iptables.IPVersion, config *networkConfiguratio
 		natArgs   []string
 		hpNatArgs []string
 	)
-	// If config.HostIP is set, the user wants IPv4 SNAT with the given address.
-	if config.HostIP != nil && ipVer == iptables.IPv4 {
-		hostAddr := config.HostIP.String()
+	// If config.HostIPv4 is set, the user wants IPv4 SNAT with the given address.
+	if config.HostIPv4 != nil && ipVer == iptables.IPv4 {
+		hostAddr := config.HostIPv4.String()
 		natArgs = []string{"-s", address, "!", "-o", config.BridgeName, "-j", "SNAT", "--to-source", hostAddr}
 		hpNatArgs = []string{"-m", "addrtype", "--src-type", "LOCAL", "-o", config.BridgeName, "-j", "SNAT", "--to-source", hostAddr}
 		// Else use MASQUERADE which picks the src-ip based on NH from the route table

libnetwork/drivers/bridge/setup_ip_tables_linux_test.go

@@ -158,7 +158,7 @@ func assertBridgeConfig(config *networkConfiguration, br *bridgeInterface, d *dr
 }
 
 // Regression test for https://github.com/moby/moby/issues/46445
-func TestSetupIP6TablesWithHostIP(t *testing.T) {
+func TestSetupIP6TablesWithHostIPv4(t *testing.T) {
 	defer netnsutils.SetupTestOSContext(t)()
 	d := newDriver()
 	dc := &configuration{
@@ -174,7 +174,7 @@ func TestSetupIP6TablesWithHostIP(t *testing.T) {
 		EnableIPMasquerade: true,
 		EnableIPv6:         true,
 		AddressIPv6:        &net.IPNet{IP: net.ParseIP("2001:db8::1"), Mask: net.CIDRMask(64, 128)},
-		HostIP:             net.ParseIP("192.0.2.2"),
+		HostIPv4:           net.ParseIP("192.0.2.2"),
 	}
 	nh, err := netlink.NewHandle()
 	if err != nil {

libnetwork/netlabel/labels.go

@@ -44,8 +44,8 @@ const (
 	// ContainerIfacePrefix can be used to override the interface prefix used inside the container
 	ContainerIfacePrefix = Prefix + ".container_iface_prefix"
 
-	// HostIP is the Source-IP Address used to SNAT container traffic
-	HostIP = Prefix + ".host_ipv4"
+	// HostIPv4 is the Source-IPv4 Address used to SNAT IPv4 container traffic
+	HostIPv4 = Prefix + ".host_ipv4"
 
 	// LocalKVClient constants represents the local kv store client
 	LocalKVClient = DriverPrivatePrefix + "localkv_client"