Move utility package 'iptables' to pkg/iptables

iptables/MAINTAINERS

@@ -0,0 +1 @@
+Michael Crosby <michael@crosbymichael.com> (@crosbymichael)

iptables/iptables.go

@@ -0,0 +1,141 @@
+package iptables
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+)
+
+type Action string
+
+const (
+	Add    Action = "-A"
+	Delete Action = "-D"
+)
+
+var (
+	ErrIptablesNotFound = errors.New("Iptables not found")
+	nat                 = []string{"-t", "nat"}
+)
+
+type Chain struct {
+	Name   string
+	Bridge string
+}
+
+func NewChain(name, bridge string) (*Chain, error) {
+	if output, err := Raw("-t", "nat", "-N", name); err != nil {
+		return nil, err
+	} else if len(output) != 0 {
+		return nil, fmt.Errorf("Error creating new iptables chain: %s", output)
+	}
+	chain := &Chain{
+		Name:   name,
+		Bridge: bridge,
+	}
+
+	if err := chain.Prerouting(Add, "-m", "addrtype", "--dst-type", "LOCAL"); err != nil {
+		return nil, fmt.Errorf("Failed to inject docker in PREROUTING chain: %s", err)
+	}
+	if err := chain.Output(Add, "-m", "addrtype", "--dst-type", "LOCAL", "!", "--dst", "127.0.0.0/8"); err != nil {
+		return nil, fmt.Errorf("Failed to inject docker in OUTPUT chain: %s", err)
+	}
+	return chain, nil
+}
+
+func RemoveExistingChain(name string) error {
+	chain := &Chain{
+		Name: name,
+	}
+	return chain.Remove()
+}
+
+func (c *Chain) Forward(action Action, ip net.IP, port int, proto, dest_addr string, dest_port int) error {
+	daddr := ip.String()
+	if ip.IsUnspecified() {
+		// iptables interprets "0.0.0.0" as "0.0.0.0/32", whereas we
+		// want "0.0.0.0/0". "0/0" is correctly interpreted as "any
+		// value" by both iptables and ip6tables.
+		daddr = "0/0"
+	}
+	if output, err := Raw("-t", "nat", fmt.Sprint(action), c.Name,
+		"-p", proto,
+		"-d", daddr,
+		"--dport", strconv.Itoa(port),
+		"!", "-i", c.Bridge,
+		"-j", "DNAT",
+		"--to-destination", net.JoinHostPort(dest_addr, strconv.Itoa(dest_port))); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return fmt.Errorf("Error iptables forward: %s", output)
+	}
+	return nil
+}
+
+func (c *Chain) Prerouting(action Action, args ...string) error {
+	a := append(nat, fmt.Sprint(action), "PREROUTING")
+	if len(args) > 0 {
+		a = append(a, args...)
+	}
+	if output, err := Raw(append(a, "-j", c.Name)...); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return fmt.Errorf("Error iptables prerouting: %s", output)
+	}
+	return nil
+}
+
+func (c *Chain) Output(action Action, args ...string) error {
+	a := append(nat, fmt.Sprint(action), "OUTPUT")
+	if len(args) > 0 {
+		a = append(a, args...)
+	}
+	if output, err := Raw(append(a, "-j", c.Name)...); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return fmt.Errorf("Error iptables output: %s", output)
+	}
+	return nil
+}
+
+func (c *Chain) Remove() error {
+	// Ignore errors - This could mean the chains were never set up
+	c.Prerouting(Delete, "-m", "addrtype", "--dst-type", "LOCAL")
+	c.Output(Delete, "-m", "addrtype", "--dst-type", "LOCAL", "!", "--dst", "127.0.0.0/8")
+	c.Output(Delete, "-m", "addrtype", "--dst-type", "LOCAL") // Created in versions <= 0.1.6
+
+	c.Prerouting(Delete)
+	c.Output(Delete)
+
+	Raw("-t", "nat", "-F", c.Name)
+	Raw("-t", "nat", "-X", c.Name)
+
+	return nil
+}
+
+// Check if an existing rule exists
+func Exists(args ...string) bool {
+	if _, err := Raw(append([]string{"-C"}, args...)...); err != nil {
+		return false
+	}
+	return true
+}
+
+func Raw(args ...string) ([]byte, error) {
+	path, err := exec.LookPath("iptables")
+	if err != nil {
+		return nil, ErrIptablesNotFound
+	}
+	if os.Getenv("DEBUG") != "" {
+		fmt.Printf("[DEBUG] [iptables]: %s, %v\n", path, args)
+	}
+	output, err := exec.Command(path, args...).CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("iptables failed: iptables %v: %s (%s)", strings.Join(args, " "), output, err)
+	}
+	return output, err
+}