105 lines
3.1 KiB
Go
105 lines
3.1 KiB
Go
//go:build !windows
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// +build !windows
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package libnetwork
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import (
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"fmt"
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"net"
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"os"
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"os/exec"
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"runtime"
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"github.com/docker/docker/libnetwork/iptables"
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"github.com/docker/docker/pkg/reexec"
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"github.com/sirupsen/logrus"
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"github.com/vishvananda/netns"
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)
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func init() {
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reexec.Register("setup-resolver", reexecSetupResolver)
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}
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const (
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// outputChain used for docker embed dns
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outputChain = "DOCKER_OUTPUT"
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//postroutingchain used for docker embed dns
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postroutingchain = "DOCKER_POSTROUTING"
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)
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func reexecSetupResolver() {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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if len(os.Args) < 4 {
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logrus.Error("invalid number of arguments..")
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os.Exit(1)
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}
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resolverIP, ipPort, _ := net.SplitHostPort(os.Args[2])
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_, tcpPort, _ := net.SplitHostPort(os.Args[3])
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rules := [][]string{
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{"-t", "nat", "-I", outputChain, "-d", resolverIP, "-p", "udp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", os.Args[2]},
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{"-t", "nat", "-I", postroutingchain, "-s", resolverIP, "-p", "udp", "--sport", ipPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
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{"-t", "nat", "-I", outputChain, "-d", resolverIP, "-p", "tcp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", os.Args[3]},
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{"-t", "nat", "-I", postroutingchain, "-s", resolverIP, "-p", "tcp", "--sport", tcpPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
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}
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f, err := os.OpenFile(os.Args[1], os.O_RDONLY, 0)
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if err != nil {
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logrus.Errorf("failed get network namespace %q: %v", os.Args[1], err)
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os.Exit(2)
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}
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defer f.Close() //nolint:gosec
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nsFD := f.Fd()
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if err = netns.Set(netns.NsHandle(nsFD)); err != nil {
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logrus.Errorf("setting into container net ns %v failed, %v", os.Args[1], err)
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os.Exit(3)
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}
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// TODO IPv6 support
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iptable := iptables.GetIptable(iptables.IPv4)
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// insert outputChain and postroutingchain
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err = iptable.RawCombinedOutputNative("-t", "nat", "-C", "OUTPUT", "-d", resolverIP, "-j", outputChain)
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if err == nil {
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iptable.RawCombinedOutputNative("-t", "nat", "-F", outputChain)
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} else {
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iptable.RawCombinedOutputNative("-t", "nat", "-N", outputChain)
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iptable.RawCombinedOutputNative("-t", "nat", "-I", "OUTPUT", "-d", resolverIP, "-j", outputChain)
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}
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err = iptable.RawCombinedOutputNative("-t", "nat", "-C", "POSTROUTING", "-d", resolverIP, "-j", postroutingchain)
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if err == nil {
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iptable.RawCombinedOutputNative("-t", "nat", "-F", postroutingchain)
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} else {
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iptable.RawCombinedOutputNative("-t", "nat", "-N", postroutingchain)
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iptable.RawCombinedOutputNative("-t", "nat", "-I", "POSTROUTING", "-d", resolverIP, "-j", postroutingchain)
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}
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for _, rule := range rules {
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if iptable.RawCombinedOutputNative(rule...) != nil {
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logrus.Errorf("set up rule failed, %v", rule)
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}
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}
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}
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func (r *resolver) setupIPTable() error {
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if r.err != nil {
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return r.err
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}
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laddr := r.conn.LocalAddr().String()
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ltcpaddr := r.tcpListen.Addr().String()
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cmd := &exec.Cmd{
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Path: reexec.Self(),
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Args: append([]string{"setup-resolver"}, r.resolverKey, laddr, ltcpaddr),
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Stdout: os.Stdout,
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Stderr: os.Stderr,
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}
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if err := cmd.Run(); err != nil {
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return fmt.Errorf("reexec failed: %v", err)
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}
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return nil
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}
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