libpod: Re-work the container's network state to help code sharing

This replaces the NetworkJail string field with a struct pointer named
NetNS. This does not try to emulate the complete NetNS interface but does
help to re-use code that just refers to c.state.NetNS.

[NO NEW TESTS NEEDED]

Signed-off-by: Doug Rabson <dfr@rabson.org>

libpod/boltdb_state_freebsd.go

@@ -6,12 +6,20 @@ package libpod
 // replaceNetNS handle network namespace transitions after updating a
 // container's state.
 func replaceNetNS(netNSPath string, ctr *Container, newState *ContainerState) error {
-	// On FreeBSD, we just record the network jail's name in our state.
-	newState.NetworkJail = netNSPath
+	if netNSPath != "" {
+		// On FreeBSD, we just record the network jail's name in our state.
+		newState.NetNS = &jailNetNS{Name: netNSPath}
+	} else {
+		newState.NetNS = nil
+	}
 	return nil
 }
 
 // getNetNSPath retrieves the netns path to be stored in the database
 func getNetNSPath(ctr *Container) string {
-	return ctr.state.NetworkJail
+	if ctr.state.NetNS != nil {
+		return ctr.state.NetNS.Name
+	} else {
+		return ""
+	}
 }

libpod/container_freebsd.go

@@ -4,11 +4,20 @@
 package libpod
 
 type containerPlatformState struct {
-	// NetworkJail is the name of the container's network VNET
+	// NetNS is the name of the container's network VNET
 	// jail.  Will only be set if config.CreateNetNS is true, or
 	// the container was told to join another container's network
 	// namespace.
-	NetworkJail string `json:"-"`
+	NetNS *jailNetNS `json:"-"`
+}
+
+type jailNetNS struct {
+	Name string `json:"-"`
+}
+
+func (ns *jailNetNS) Path() string {
+	// The jail name approximately corresponds to the Linux netns path
+	return ns.Name
 }
 
 func networkDisabled(c *Container) (bool, error) {
@@ -16,7 +25,7 @@ func networkDisabled(c *Container) (bool, error) {
 		return false, nil
 	}
 	if !c.config.PostConfigureNetNS {
-		return c.state.NetworkJail == "", nil
+		return c.state.NetNS != nil, nil
 	}
 	return false, nil
 }

libpod/container_internal_freebsd.go

@@ -26,8 +26,8 @@ var (
 
 // Network stubs to decouple container_internal_freebsd.go from
 // networking_freebsd.go so they can be reviewed separately.
-func (r *Runtime) createNetNS(ctr *Container) (netJail string, q map[string]types.StatusBlock, retErr error) {
-	return "", nil, errors.New("not implemented (*Runtime) createNetNS")
+func (r *Runtime) createNetNS(ctr *Container) (netJail *jailNetNS, q map[string]types.StatusBlock, retErr error) {
+	return nil, nil, errors.New("not implemented (*Runtime) createNetNS")
 }
 
 func (r *Runtime) teardownNetNS(ctr *Container) error {
@@ -51,7 +51,7 @@ func (c *Container) unmountSHM(path string) error {
 func (c *Container) prepare() error {
 	var (
 		wg                              sync.WaitGroup
-		jailName                        string
+		ctrNS                           *jailNetNS
 		networkStatus                   map[string]types.StatusBlock
 		createNetNSErr, mountStorageErr error
 		mountPoint                      string
@@ -63,9 +63,9 @@ func (c *Container) prepare() error {
 	go func() {
 		defer wg.Done()
 		// Set up network namespace if not already set up
-		noNetNS := c.state.NetworkJail == ""
+		noNetNS := c.state.NetNS == nil
 		if c.config.CreateNetNS && noNetNS && !c.config.PostConfigureNetNS {
-			jailName, networkStatus, createNetNSErr = c.runtime.createNetNS(c)
+			ctrNS, networkStatus, createNetNSErr = c.runtime.createNetNS(c)
 			if createNetNSErr != nil {
 				return
 			}
@@ -74,7 +74,7 @@ func (c *Container) prepare() error {
 			defer tmpStateLock.Unlock()
 
 			// Assign NetNS attributes to container
-			c.state.NetworkJail = jailName
+			c.state.NetNS = ctrNS
 			c.state.NetworkStatus = networkStatus
 		}
 	}()
@@ -164,7 +164,7 @@ func (c *Container) addNetworkContainer(g *generate.Generator, ctr string) error
 	if err != nil {
 		return fmt.Errorf("retrieving dependency %s of container %s from state: %w", ctr, c.ID(), err)
 	}
-	g.AddAnnotation("org.freebsd.parentJail", nsCtr.state.NetworkJail)
+	g.AddAnnotation("org.freebsd.parentJail", nsCtr.state.NetNS.Name)
 	return nil
 }
 
@@ -187,7 +187,7 @@ func openDirectory(path string) (fd int, err error) {
 
 func (c *Container) addNetworkNamespace(g *generate.Generator) error {
 	if c.config.CreateNetNS {
-		g.AddAnnotation("org.freebsd.parentJail", c.state.NetworkJail)
+		g.AddAnnotation("org.freebsd.parentJail", c.state.NetNS.Name)
 	}
 	return nil
 }
@@ -272,7 +272,7 @@ func (c *Container) isSlirp4netnsIPv6() (bool, error) {
 
 // check for net=none
 func (c *Container) hasNetNone() bool {
-	return c.state.NetworkJail == ""
+	return c.state.NetNS == nil
 }
 
 func setVolumeAtime(mountPoint string, st os.FileInfo) error {