2 files changed, 92 insertions, 5 deletions
diff --git a/libpod/image/image.go b/libpod/image/image.go
index 72f07dad1..c5939e055 100644
--- a/libpod/image/image.go
+++ b/libpod/image/image.go
@@ -1212,3 +1212,70 @@ func (i *Image) newImageEvent(status events.Status) {
 		logrus.Infof("unable to write event to %s", i.imageruntime.EventsLogFilePath)
 	}
 }
+
+// LayerInfo keeps information of single layer
+type LayerInfo struct {
+	// Layer ID
+	ID string
+	// Parent ID of current layer.
+	ParentID string
+	// ChildID of current layer.
+	// there can be multiple children in case of fork
+	ChildID []string
+	// RepoTag will have image repo names, if layer is top layer of image
+	RepoTags []string
+	// Size stores Uncompressed size of layer.
+	Size int64
+}
+
+// GetLayersMapWithImageInfo returns map of image-layers, with associated information like RepoTags, parent and list of child layers.
+func GetLayersMapWithImageInfo(imageruntime *Runtime) (map[string]*LayerInfo, error) {
+
+	// Memory allocated to store map of layers with key LayerID.
+	// Map will build dependency chain with ParentID and ChildID(s)
+	layerInfoMap := make(map[string]*LayerInfo)
+
+	// scan all layers & fill size and parent id for each layer in layerInfoMap
+	layers, err := imageruntime.store.Layers()
+	if err != nil {
+		return nil, err
+	}
+	for _, layer := range layers {
+		_, ok := layerInfoMap[layer.ID]
+		if !ok {
+			layerInfoMap[layer.ID] = &LayerInfo{
+				ID:       layer.ID,
+				Size:     layer.UncompressedSize,
+				ParentID: layer.Parent,
+			}
+		} else {
+			return nil, fmt.Errorf("detected multiple layers with the same ID %q", layer.ID)
+		}
+	}
+
+	// scan all layers & add all childs for each layers to layerInfo
+	for _, layer := range layers {
+		_, ok := layerInfoMap[layer.ID]
+		if ok {
+			if layer.Parent != "" {
+				layerInfoMap[layer.Parent].ChildID = append(layerInfoMap[layer.Parent].ChildID, layer.ID)
+			}
+		} else {
+			return nil, fmt.Errorf("lookup error: layer-id  %s, not found", layer.ID)
+		}
+	}
+
+	// Add the Repo Tags to Top layer of each image.
+	imgs, err := imageruntime.store.Images()
+	if err != nil {
+		return nil, err
+	}
+	for _, img := range imgs {
+		e, ok := layerInfoMap[img.TopLayer]
+		if !ok {
+			return nil, fmt.Errorf("top-layer for image %s not found local store", img.ID)
+		}
+		e.RepoTags = append(e.RepoTags, img.Names...)
+	}
+	return layerInfoMap, nil
+}
diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index 80d7d8213..d8b0cffcb 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -134,6 +134,15 @@ type slirp4netnsCmd struct {
 	Args    slirp4netnsCmdArg `json:"arguments"`
 }
 
+func checkSlirpFlags(path string) (bool, bool, error) {
+	cmd := exec.Command(path, "--help")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, false, err
+	}
+	return strings.Contains(string(out), "--disable-host-loopback"), strings.Contains(string(out), "--mtu"), nil
+}
+
 // Configure the network namespace for a rootless container
 func (r *Runtime) setupRootlessNetNS(ctr *Container) (err error) {
 	defer ctr.rootlessSlirpSyncR.Close()
@@ -159,13 +168,24 @@ func (r *Runtime) setupRootlessNetNS(ctr *Container) (err error) {
 
 	havePortMapping := len(ctr.Config().PortMappings) > 0
 	apiSocket := filepath.Join(r.ociRuntime.tmpDir, fmt.Sprintf("%s.net", ctr.config.ID))
-	var cmd *exec.Cmd
+
+	cmdArgs := []string{}
 	if havePortMapping {
-		// if we need ports to be mapped from the host, create a API socket to use for communicating with slirp4netns.
-		cmd = exec.Command(path, "-c", "-e", "3", "-r", "4", "--api-socket", apiSocket, fmt.Sprintf("%d", ctr.state.PID), "tap0")
-	} else {
-		cmd = exec.Command(path, "-c", "-e", "3", "-r", "4", fmt.Sprintf("%d", ctr.state.PID), "tap0")
+		cmdArgs = append(cmdArgs, "--api-socket", apiSocket, fmt.Sprintf("%d", ctr.state.PID))
 	}
+	dhp, mtu, err := checkSlirpFlags(path)
+	if err != nil {
+		return errors.Wrapf(err, "error checking slirp4netns binary %s", path)
+	}
+	if dhp {
+		cmdArgs = append(cmdArgs, "--disable-host-loopback")
+	}
+	if mtu {
+		cmdArgs = append(cmdArgs, "--mtu", "65520")
+	}
+	cmdArgs = append(cmdArgs, "-c", "-e", "3", "-r", "4", fmt.Sprintf("%d", ctr.state.PID), "tap0")
+
+	cmd := exec.Command(path, cmdArgs...)
 
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Setpgid: true,