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moby--moby/libnetwork/resolver_unix.go
Santhosh Manohar 61510dc222 Move the iptables setup for embedded DNS into a reexec process
Signed-off-by: Santhosh Manohar <santhosh@docker.com>
2016-04-15 23:37:20 -07:00

77 lines
2 KiB
Go

// +build !windows
package libnetwork
import (
"fmt"
"net"
"os"
"os/exec"
"runtime"
log "github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/reexec"
"github.com/docker/libnetwork/iptables"
"github.com/vishvananda/netns"
)
func init() {
reexec.Register("setup-resolver", reexecSetupResolver)
}
func reexecSetupResolver() {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
if len(os.Args) < 4 {
log.Error("invalid number of arguments..")
os.Exit(1)
}
_, ipPort, _ := net.SplitHostPort(os.Args[2])
_, tcpPort, _ := net.SplitHostPort(os.Args[3])
rules := [][]string{
{"-t", "nat", "-A", "OUTPUT", "-d", resolverIP, "-p", "udp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", os.Args[2]},
{"-t", "nat", "-A", "POSTROUTING", "-s", resolverIP, "-p", "udp", "--sport", ipPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
{"-t", "nat", "-A", "OUTPUT", "-d", resolverIP, "-p", "tcp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", os.Args[3]},
{"-t", "nat", "-A", "POSTROUTING", "-s", resolverIP, "-p", "tcp", "--sport", tcpPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
}
f, err := os.OpenFile(os.Args[1], os.O_RDONLY, 0)
if err != nil {
log.Errorf("failed get network namespace %q: %v", os.Args[1], err)
os.Exit(2)
}
defer f.Close()
nsFD := f.Fd()
if err = netns.Set(netns.NsHandle(nsFD)); err != nil {
log.Errorf("setting into container net ns %v failed, %v", os.Args[1], err)
os.Exit(3)
}
for _, rule := range rules {
if iptables.RawCombinedOutputNative(rule...) != nil {
log.Errorf("setting up rule failed, %v", rule)
}
}
}
func (r *resolver) setupIPTable() error {
if r.err != nil {
return r.err
}
laddr := r.conn.LocalAddr().String()
ltcpaddr := r.tcpListen.Addr().String()
cmd := &exec.Cmd{
Path: reexec.Self(),
Args: append([]string{"setup-resolver"}, r.sb.Key(), laddr, ltcpaddr),
Stdout: os.Stdout,
Stderr: os.Stderr,
}
if err := cmd.Run(); err != nil {
return fmt.Errorf("reexec failed: %v", err)
}
return nil
}