libnetwork/iptables: Use UsingFirewalld in remaining firewalld paths

AddInterfaceFirewalld and DelInterfaceFirewalld read firewalldRunning
directly, so they silently no-oped when called before any iptables
operation had triggered firewalld initialization. Now they call
UsingFirewalld, which initializes firewalld on first use.

The firewalld tests called firewalldInit directly and then ran the
same initialization again through the once guard, creating a second
D-Bus connection and signal-handler goroutine. Now they assert
UsingFirewalld instead.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

daemon/libnetwork/iptables/firewalld.go

@@ -313,7 +313,7 @@ func setupDockerForwardingPolicy() (bool, error) {
 // AddInterfaceFirewalld adds the interface to the trusted zone. It is a
 // no-op if firewalld is not running.
 func AddInterfaceFirewalld(intf string) error {
-	if !firewalldRunning.Load() {
+	if !UsingFirewalld() {
 		return nil
 	}
 
@@ -339,7 +339,7 @@ func AddInterfaceFirewalld(intf string) error {
 // DelInterfaceFirewalld removes the interface from the trusted zone It is a
 // no-op if firewalld is not running.
 func DelInterfaceFirewalld(intf string) error {
-	if !firewalldRunning.Load() {
+	if !UsingFirewalld() {
 		return nil
 	}
 

daemon/libnetwork/iptables/firewalld_test.go

@@ -16,8 +16,6 @@ func skipIfNoFirewalld(t *testing.T) {
 	if err != nil {
 		t.Skipf("cannot connect to D-bus system bus: %v", err)
 	}
-	defer conn.Close()
-
 	var zone string
 	err = conn.Object(dbusInterface, dbusPath).Call(dbusInterface+".getDefaultZone", 0).Store(&zone)
 	if err != nil {
@@ -25,10 +23,10 @@ func skipIfNoFirewalld(t *testing.T) {
 	}
 }
 
-func TestFirewalldInit(t *testing.T) {
+func TestUsingFirewalld(t *testing.T) {
 	skipIfNoFirewalld(t)
-	if err := firewalldInit(); err != nil {
-		t.Fatal(err)
+	if !UsingFirewalld() {
+		t.Fatal("firewalld is running, but UsingFirewalld() is false")
 	}
 }
 
@@ -97,11 +95,10 @@ func TestPassthrough(t *testing.T) {
 		"-j", "ACCEPT",
 	}
 
-	err := firewalldInit()
-	if err != nil {
-		t.Fatal(err)
+	if !UsingFirewalld() {
+		t.Fatal("firewalld is running, but UsingFirewalld() is false")
 	}
-	_, err = passthrough(IPv4, rule1...)
+	_, err := passthrough(IPv4, rule1...)
 	if err != nil {
 		t.Fatal(err)
 	}