Add remap command for TCP listen port remapping (Closes #169)

checkpointctl.go

@@ -33,6 +33,8 @@ func main() {
 
 	rootCommand.AddCommand(cmd.BuildCmd())
 
+	rootCommand.AddCommand(cmd.Remap())
+
 	rootCommand.Version = version
 
 	if err := rootCommand.Execute(); err != nil {

cmd/remap.go

@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/checkpoint-restore/checkpointctl/internal"
+	metadata "github.com/checkpoint-restore/checkpointctl/lib"
+	"github.com/spf13/cobra"
+)
+
+var tcpListenRemap *string
+
+func Remap() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "remap <checkpoint-path>",
+		Short: "Remap TCP listen ports in a container checkpoint archive",
+		Long: `The 'remap' command allows remapping TCP listen ports in a checkpoint archive.
+This is useful when the port originally bound to a socket needs to be changed before restoring.
+
+Port mappings are specified using the --tcp-listen-remap flag in the format:
+  old_port:new_port
+
+Multiple port mappings can be specified by separating them with commas:
+  --tcp-listen-remap 8080:80,8443:443
+
+Example:
+  checkpointctl remap checkpoint.tar --tcp-listen-remap 8080:80`,
+		Args: cobra.ExactArgs(1),
+		RunE: remapTCPPorts,
+	}
+
+	tcpListenRemap = cmd.Flags().String(
+		"tcp-listen-remap",
+		"",
+		"TCP listen port remapping in format old_port:new_port (e.g., 8080:80). Multiple mappings can be separated by commas.",
+	)
+
+	cmd.MarkFlagRequired("tcp-listen-remap")
+
+	return cmd
+}
+
+func remapTCPPorts(cmd *cobra.Command, args []string) error {
+	checkpointPath := args[0]
+
+	// Parse port mappings
+	portMappings, err := parsePortMappings(*tcpListenRemap)
+	if err != nil {
+		return fmt.Errorf("failed to parse port mappings: %w", err)
+	}
+
+	if len(portMappings) == 0 {
+		return fmt.Errorf("no valid port mappings specified")
+	}
+
+	// Create temporary directory for extraction
+	tempDir, err := os.MkdirTemp("", "checkpointctl-remap-")
+	if err != nil {
+		return fmt.Errorf("failed to create temporary directory: %w", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Extract files.img from checkpoint
+	filesImgPath := filepath.Join(metadata.CheckpointDirectory, "files.img")
+	if err := internal.UntarFiles(checkpointPath, tempDir, []string{filesImgPath}); err != nil {
+		return fmt.Errorf("failed to extract files.img from checkpoint: %w", err)
+	}
+
+	extractedFilesImgPath := filepath.Join(tempDir, filesImgPath)
+
+	// Perform port remapping
+	modified, err := internal.RemapTCPListenPorts(extractedFilesImgPath, portMappings)
+	if err != nil {
+		return fmt.Errorf("failed to remap TCP ports: %w", err)
+	}
+
+	if !modified {
+		fmt.Println("No TCP listen sockets were found matching the specified port mappings")
+		return nil
+	}
+
+	// Repack the modified files.img back into the checkpoint archive
+	if err := internal.RepackFileToArchive(checkpointPath, filesImgPath, extractedFilesImgPath); err != nil {
+		return fmt.Errorf("failed to repack checkpoint archive: %w", err)
+	}
+
+	fmt.Printf("Successfully remapped TCP listen ports in %s\n", checkpointPath)
+	return nil
+}
+
+func parsePortMappings(mappingStr string) (map[uint32]uint32, error) {
+	mappings := make(map[uint32]uint32)
+
+	if mappingStr == "" {
+		return mappings, nil
+	}
+
+	parts := strings.Split(mappingStr, ",")
+	for _, part := range parts {
+		part = strings.TrimSpace(part)
+		if part == "" {
+			continue
+		}
+
+		ports := strings.Split(part, ":")
+		if len(ports) != 2 {
+			return nil, fmt.Errorf("invalid port mapping format: %s (expected old_port:new_port)", part)
+		}
+
+		oldPort, err := strconv.ParseUint(strings.TrimSpace(ports[0]), 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("invalid old port '%s': %w", ports[0], err)
+		}
+
+		newPort, err := strconv.ParseUint(strings.TrimSpace(ports[1]), 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("invalid new port '%s': %w", ports[1], err)
+		}
+
+		if oldPort == 0 || oldPort > 65535 {
+			return nil, fmt.Errorf("old port %d is out of valid range (1-65535)", oldPort)
+		}
+		if newPort == 0 || newPort > 65535 {
+			return nil, fmt.Errorf("new port %d is out of valid range (1-65535)", newPort)
+		}
+
+		mappings[uint32(oldPort)] = uint32(newPort)
+	}
+
+	return mappings, nil
+}