clone from danieldin95

vendor/github.com/moby/libnetwork/iptables/iptables.go

@@ -0,0 +1,371 @@
+package iptables
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os/exec"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// Action signifies the iptable action.
+type Action string
+
+// Table refers to Nat, Filter or Mangle.
+type Table string
+
+const (
+	// Append appends the rule at the end of the chain.
+	Append Action = "-A"
+	// Delete deletes the rule from the chain.
+	Delete Action = "-D"
+	// Insert inserts the rule at the top of the chain.
+	Insert Action = "-I"
+	// Nat table is used for nat translation rules.
+	Nat Table = "nat"
+	// Filter table is used for filter rules.
+	Filter Table = "filter"
+	// Mangle table is used for mangling the packet.
+	Mangle Table = "mangle"
+)
+
+var (
+	iptablesPath  string
+	supportsXlock = false
+	// used to lock iptables commands if xtables lock is not supported
+	bestEffortLock sync.Mutex
+	// ErrIptablesNotFound is returned when the rule is not found.
+	ErrIptablesNotFound = errors.New("Iptables not found")
+)
+
+// ChainInfo defines the iptables chain.
+type ChainInfo struct {
+	Name        string
+	Table       Table
+	HairpinMode bool
+}
+
+// ChainError is returned to represent errors during ip table operation.
+type ChainError struct {
+	Chain  string
+	Output []byte
+}
+
+func (e ChainError) Error() string {
+	return fmt.Sprintf("Error iptables %s: %s", e.Chain, string(e.Output))
+}
+
+func initCheck() error {
+
+	if iptablesPath == "" {
+		path, err := exec.LookPath("iptables")
+		if err != nil {
+			return ErrIptablesNotFound
+		}
+		iptablesPath = path
+		supportsXlock = exec.Command(iptablesPath, "--wait", "-L", "-n").Run() == nil
+	}
+	return nil
+}
+
+// NewChain adds a new chain to ip table.
+func NewChain(name string, table Table, hairpinMode bool) (*ChainInfo, error) {
+	c := &ChainInfo{
+		Name:        name,
+		Table:       table,
+		HairpinMode: hairpinMode,
+	}
+	if string(c.Table) == "" {
+		c.Table = Filter
+	}
+
+	// Add chain if it doesn't exist
+	if _, err := Raw("-t", string(c.Table), "-n", "-L", c.Name); err != nil {
+		if output, err := Raw("-t", string(c.Table), "-N", c.Name); err != nil {
+			return nil, err
+		} else if len(output) != 0 {
+			return nil, fmt.Errorf("Could not create %s/%s chain: %s", c.Table, c.Name, output)
+		}
+	}
+	return c, nil
+}
+
+// ProgramChain is used to add rules to a chain
+func ProgramChain(c *ChainInfo, bridgeName string, hairpinMode, enable bool) error {
+	if c.Name == "" {
+		return fmt.Errorf("Could not program chain, missing chain name.")
+	}
+
+	switch c.Table {
+	case Nat:
+		preroute := []string{
+			"-m", "addrtype",
+			"--dst-type", "LOCAL",
+			"-j", c.Name}
+		if !Exists(Nat, "PREROUTING", preroute...) && enable {
+			if err := c.Prerouting(Append, preroute...); err != nil {
+				return fmt.Errorf("Failed to inject docker in PREROUTING chain: %s", err)
+			}
+		} else if Exists(Nat, "PREROUTING", preroute...) && !enable {
+			if err := c.Prerouting(Delete, preroute...); err != nil {
+				return fmt.Errorf("Failed to remove docker in PREROUTING chain: %s", err)
+			}
+		}
+		output := []string{
+			"-m", "addrtype",
+			"--dst-type", "LOCAL",
+			"-j", c.Name}
+		if !hairpinMode {
+			output = append(output, "!", "--dst", "127.0.0.0/8")
+		}
+		if !Exists(Nat, "OUTPUT", output...) && enable {
+			if err := c.Output(Append, output...); err != nil {
+				return fmt.Errorf("Failed to inject docker in OUTPUT chain: %s", err)
+			}
+		} else if Exists(Nat, "OUTPUT", output...) && !enable {
+			if err := c.Output(Delete, output...); err != nil {
+				return fmt.Errorf("Failed to inject docker in OUTPUT chain: %s", err)
+			}
+		}
+	case Filter:
+		if bridgeName == "" {
+			return fmt.Errorf("Could not program chain %s/%s, missing bridge name.",
+				c.Table, c.Name)
+		}
+		link := []string{
+			"-o", bridgeName,
+			"-j", c.Name}
+		if !Exists(Filter, "FORWARD", link...) && enable {
+			insert := append([]string{string(Insert), "FORWARD"}, link...)
+			if output, err := Raw(insert...); err != nil {
+				return err
+			} else if len(output) != 0 {
+				return fmt.Errorf("Could not create linking rule to %s/%s: %s", c.Table, c.Name, output)
+			}
+		} else if Exists(Filter, "FORWARD", link...) && !enable {
+			del := append([]string{string(Delete), "FORWARD"}, link...)
+			if output, err := Raw(del...); err != nil {
+				return err
+			} else if len(output) != 0 {
+				return fmt.Errorf("Could not delete linking rule from %s/%s: %s", c.Table, c.Name, output)
+			}
+
+		}
+	}
+	return nil
+}
+
+// RemoveExistingChain removes existing chain from the table.
+func RemoveExistingChain(name string, table Table) error {
+	c := &ChainInfo{
+		Name:  name,
+		Table: table,
+	}
+	if string(c.Table) == "" {
+		c.Table = Filter
+	}
+	return c.Remove()
+}
+
+// Forward adds forwarding rule to 'filter' table and corresponding nat rule to 'nat' table.
+func (c *ChainInfo) Forward(action Action, ip net.IP, port int, proto, destAddr string, destPort int, bridgeName string) 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"
+	}
+	args := []string{"-t", string(Nat), string(action), c.Name,
+		"-p", proto,
+		"-d", daddr,
+		"--dport", strconv.Itoa(port),
+		"-j", "DNAT",
+		"--to-destination", net.JoinHostPort(destAddr, strconv.Itoa(destPort))}
+	if !c.HairpinMode {
+		args = append(args, "!", "-i", bridgeName)
+	}
+	if output, err := Raw(args...); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return ChainError{Chain: "FORWARD", Output: output}
+	}
+
+	if output, err := Raw("-t", string(Filter), string(action), c.Name,
+		"!", "-i", bridgeName,
+		"-o", bridgeName,
+		"-p", proto,
+		"-d", destAddr,
+		"--dport", strconv.Itoa(destPort),
+		"-j", "ACCEPT"); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return ChainError{Chain: "FORWARD", Output: output}
+	}
+
+	if output, err := Raw("-t", string(Nat), string(action), "POSTROUTING",
+		"-p", proto,
+		"-s", destAddr,
+		"-d", destAddr,
+		"--dport", strconv.Itoa(destPort),
+		"-j", "MASQUERADE"); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return ChainError{Chain: "FORWARD", Output: output}
+	}
+
+	return nil
+}
+
+// Link adds reciprocal ACCEPT rule for two supplied IP addresses.
+// Traffic is allowed from ip1 to ip2 and vice-versa
+func (c *ChainInfo) Link(action Action, ip1, ip2 net.IP, port int, proto string, bridgeName string) error {
+	if output, err := Raw("-t", string(Filter), string(action), c.Name,
+		"-i", bridgeName, "-o", bridgeName,
+		"-p", proto,
+		"-s", ip1.String(),
+		"-d", ip2.String(),
+		"--dport", strconv.Itoa(port),
+		"-j", "ACCEPT"); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return fmt.Errorf("Error iptables forward: %s", output)
+	}
+	if output, err := Raw("-t", string(Filter), string(action), c.Name,
+		"-i", bridgeName, "-o", bridgeName,
+		"-p", proto,
+		"-s", ip2.String(),
+		"-d", ip1.String(),
+		"--sport", strconv.Itoa(port),
+		"-j", "ACCEPT"); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return fmt.Errorf("Error iptables forward: %s", output)
+	}
+	return nil
+}
+
+// Prerouting adds linking rule to nat/PREROUTING chain.
+func (c *ChainInfo) Prerouting(action Action, args ...string) error {
+	a := []string{"-t", string(Nat), string(action), "PREROUTING"}
+	if len(args) > 0 {
+		a = append(a, args...)
+	}
+	if output, err := Raw(a...); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return ChainError{Chain: "PREROUTING", Output: output}
+	}
+	return nil
+}
+
+// Output adds linking rule to an OUTPUT chain.
+func (c *ChainInfo) Output(action Action, args ...string) error {
+	a := []string{"-t", string(c.Table), string(action), "OUTPUT"}
+	if len(args) > 0 {
+		a = append(a, args...)
+	}
+	if output, err := Raw(a...); err != nil {
+		return err
+	} else if len(output) != 0 {
+		return ChainError{Chain: "OUTPUT", Output: output}
+	}
+	return nil
+}
+
+// Remove removes the chain.
+func (c *ChainInfo) Remove() error {
+	// Ignore errors - This could mean the chains were never set up
+	if c.Table == Nat {
+		c.Prerouting(Delete, "-m", "addrtype", "--dst-type", "LOCAL", "-j", c.Name)
+		c.Output(Delete, "-m", "addrtype", "--dst-type", "LOCAL", "!", "--dst", "127.0.0.0/8", "-j", c.Name)
+		c.Output(Delete, "-m", "addrtype", "--dst-type", "LOCAL", "-j", c.Name) // Created in versions <= 0.1.6
+
+		c.Prerouting(Delete)
+		c.Output(Delete)
+	}
+	Raw("-t", string(c.Table), "-F", c.Name)
+	Raw("-t", string(c.Table), "-X", c.Name)
+	return nil
+}
+
+// Exists checks if a rule exists
+func Exists(table Table, chain string, rule ...string) bool {
+	if string(table) == "" {
+		table = Filter
+	}
+
+	// iptables -C, --check option was added in v.1.4.11
+	// http://ftp.netfilter.org/pub/iptables/changes-iptables-1.4.11.txt
+
+	// try -C
+	// if exit status is 0 then return true, the rule exists
+	if _, err := Raw(append([]string{
+		"-t", string(table), "-C", chain}, rule...)...); err == nil {
+		return true
+	}
+
+	// parse "iptables -S" for the rule (this checks rules in a specific chain
+	// in a specific table)
+	ruleString := strings.Join(rule, " ")
+	ruleString = chain + " " + ruleString
+	existingRules, _ := exec.Command(iptablesPath, "-t", string(table), "-S", chain).Output()
+
+	return strings.Contains(string(existingRules), ruleString)
+}
+
+// Raw calls 'iptables' system command, passing supplied arguments.
+func Raw(args ...string) ([]byte, error) {
+	if firewalldRunning {
+		output, err := Passthrough(Iptables, args...)
+		if err == nil || !strings.Contains(err.Error(), "was not provided by any .service files") {
+			return output, err
+		}
+
+	}
+
+	if err := initCheck(); err != nil {
+		return nil, err
+	}
+	if supportsXlock {
+		args = append([]string{"--wait"}, args...)
+	} else {
+		bestEffortLock.Lock()
+		defer bestEffortLock.Unlock()
+	}
+
+	logrus.Debugf("%s, %v", iptablesPath, args)
+
+	output, err := exec.Command(iptablesPath, args...).CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("iptables failed: iptables %v: %s (%s)", strings.Join(args, " "), output, err)
+	}
+
+	// ignore iptables' message about xtables lock
+	if strings.Contains(string(output), "waiting for it to exit") {
+		output = []byte("")
+	}
+
+	return output, err
+}
+
+// RawCombinedOutput inernally calls the Raw function and returns a non nil
+// error if Raw returned a non nil error or a non empty output
+func RawCombinedOutput(args ...string) error {
+	if output, err := Raw(args...); err != nil || len(output) != 0 {
+		return fmt.Errorf("%s (%v)", string(output), err)
+	}
+	return nil
+}
+
+// ExistChain checks if a chain exists
+func ExistChain(chain string, table Table) bool {
+	if _, err := Raw("-t", string(table), "-L", chain); err == nil {
+		return true
+	}
+	return false
+}