Working alpha version, interact with nf through ip6tables sub-process

Makefile

+all: nat66-docker
+
+nat66-docker: docker.go ip6tables.go main.go
+	go build -o nat66-docker
\ No newline at end of file

docker.go

 package main
 
 import (
-	"fmt"
-
 	"github.com/fsouza/go-dockerclient"
 )
 
-func main() {
+// bindings store network settings for each known container
+var bindings map[string]*docker.NetworkSettings
+
+// clear bindings by deleting corresponding port forwarding
+func clear_bindings() {
+	for id, net := range bindings {
+		ipv6addr := net.GlobalIPv6Address
+		for port, binds := range net.Ports {
+			for b := range binds {
+				del_nat66_portfwd(*dev, port.Proto(), binds[b].HostPort, ipv6addr, port.Port())
+			}
+		}
+		delete(bindings, id)
+	}
+}
+
+func init_docker() {
 	endpoint := "unix:///var/run/docker.sock"
+	bindings := make(map[string]*docker.NetworkSettings)
+
+	// Init client to Docker socket
 	client, _ := docker.NewClient(endpoint)
-	imgs, _ := client.ListImages(docker.ListImagesOptions{All: false})
-	for _, img := range imgs {
-		fmt.Println("ID: ", img.ID)
-		fmt.Println("RepoTags: ", img.RepoTags)
-		fmt.Println("Created: ", img.Created)
-		fmt.Println("Size: ", img.Size)
-		fmt.Println("VirtualSize: ", img.VirtualSize)
-		fmt.Println("ParentId: ", img.ParentID)
+	events := make(chan *docker.APIEvents)
+	client.AddEventListener(events)
+
+	// Iterate over docker event
+	for msg := range events {
+
+		// When a container start ...
+		if msg.Action == "start" {
+			c, err := client.InspectContainer(msg.ID)
+			if err == nil {
+				net := c.NetworkSettings
+				bindings[msg.ID] = net
+				ipv6addr := net.GlobalIPv6Address
+				for port, binds := range net.Ports {
+					for b := range binds {
+						add_nat66_portfwd(*dev, port.Proto(), binds[b].HostPort, ipv6addr, port.Port())
+					}
 				}
 			}
+		}
+
+		// When a container die
+		if msg.Action == "die" {
+			_, err := client.InspectContainer(msg.ID)
+			if err == nil {
+				if net, ok := bindings[msg.ID]; ok {
+					ipv6addr := net.GlobalIPv6Address
+					for port, binds := range net.Ports {
+						for b := range binds {
+							del_nat66_portfwd(*dev, port.Proto(), binds[b].HostPort, ipv6addr, port.Port())
+						}
+					}
+					delete(bindings, msg.ID)
+				}
+			}
+		}
+	}
+
+	unset_nat66_postrouting(*dev, *prefix)
+}

ip6tables.go

+package main
+
+import (
+	"log"
+	"os/exec"
+	"strings"
+)
+
+func set_nat66_postrouting(dev, prefix string) {
+	cmd := new(exec.Cmd)
+	cmd.Path = "/sbin/ip6tables"
+	cmd.Args = []string{
+		"/sbin/ip6tables", "-t", "nat", "-A", "POSTROUTING",
+		"-o", dev, "-s", prefix,
+		"-j", "MASQUERADE",
+	}
+	log.Println("NAT66 set postrouting: " + strings.Join(cmd.Args, " "))
+	err := cmd.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func unset_nat66_postrouting(dev, prefix string) {
+	cmd := new(exec.Cmd)
+	cmd.Path = "/sbin/ip6tables"
+	cmd.Args = []string{
+		"/sbin/ip6tables", "-t", "nat", "-D", "POSTROUTING",
+		"-o", dev, "-s", prefix,
+		"-j", "MASQUERADE",
+	}
+	log.Println("NAT66 unset postrouting: " + strings.Join(cmd.Args, " "))
+	err := cmd.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func add_nat66_portfwd(dev, proto, dport, target_ipv6, target_port string) {
+	cmd := new(exec.Cmd)
+	cmd.Path = "/sbin/ip6tables"
+	cmd.Args = []string{
+		"/sbin/ip6tables", "-t", "nat", "-A", "PREROUTING",
+		"-i", dev, "-p", proto, "--dport", dport,
+		"-j", "DNAT",
+		"--to-destination", "[" + target_ipv6 + "]:" + target_port,
+	}
+	log.Println("NAT66 add portfwd: " + strings.Join(cmd.Args, " "))
+	err := cmd.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func del_nat66_portfwd(dev, proto, dport, target_ipv6, target_port string) {
+	cmd := new(exec.Cmd)
+	cmd.Path = "/sbin/ip6tables"
+	cmd.Args = []string{
+		"/sbin/ip6tables", "-t", "nat", "-D", "PREROUTING",
+		"-i", dev, "-p", proto, "--dport", dport,
+		"-j", "DNAT",
+		"--to-destination", "[" + target_ipv6 + "]:" + target_port,
+	}
+	log.Println("NAT66 del portfwd: " + strings.Join(cmd.Args, " "))
+	err := cmd.Run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}

main.go

+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+)
+
+var dev = flag.String("dev", "", "Egress network device")
+var prefix = flag.String("prefix", "", "Internal IPv6 prefix")
+
+func main() {
+
+	flag.Parse()
+	if flag.NArg() != 0 {
+		log.Fatal("Bad number of argument: %d, expected 0", flag.NArg())
+		os.Exit(2)
+	}
+	if *dev == "" && *prefix == "" {
+		log.Fatal("Flag -dev and -prefix are mandatory")
+		os.Exit(2)
+	}
+
+	// Set initial NAT rule
+	set_nat66_postrouting(*dev, *prefix)
+
+	// Clear when signal received
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+	go func() {
+		for range c {
+			unset_nat66_postrouting(*dev, *prefix)
+			clear_bindings()
+		}
+	}()
+
+	// Start docker
+	init_docker()
+
+}