rootless: use RootlessKit port forwarder

RootlessKit port forwarder has a lot of advantages over the slirp4netns port forwarder:

* Very high throughput.
  Benchmark result on Travis: socat: 5.2 Gbps, slirp4netns: 8.3 Gbps, RootlessKit: 27.3 Gbps
  (https://travis-ci.org/rootless-containers/rootlesskit/builds/597056377)

* Connections from the host are treated as 127.0.0.1 rather than 10.0.2.2 in the namespace.
  No UDP issue (#4586)

* No tcp_rmem issue (#4537)

* Probably works with IPv6. Even if not, it is trivial to support IPv6.  (#4311)

* Easily extensible for future support of SCTP

* Easily extensible for future support of `lxc-user-nic` SUID network

RootlessKit port forwarder has been already adopted as the default port forwarder by Rootless Docker/Moby,
and no issue has been reported AFAIK.

As the port forwarder is imported as a Go package, no `rootlesskit` binary is required for Podman.

Fix #4586
May-fix #4559
Fix #4537
May-fix #4311

See https://github.com/rootless-containers/rootlesskit/blob/v0.7.0/pkg/port/builtin/builtin.go

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

1 files changed, 134 insertions, 0 deletions

diff --git a/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/child/child.go b/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/child/child.go
new file mode 100644
index 000000000..5477dda51
--- /dev/null
+++ b/vendor/github.com/rootless-containers/rootlesskit/pkg/port/builtin/child/child.go
@@ -0,0 +1,134 @@
+package child
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"os"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+
+	"github.com/rootless-containers/rootlesskit/pkg/msgutil"
+	"github.com/rootless-containers/rootlesskit/pkg/port"
+	"github.com/rootless-containers/rootlesskit/pkg/port/builtin/msg"
+	opaquepkg "github.com/rootless-containers/rootlesskit/pkg/port/builtin/opaque"
+)
+
+func NewDriver(logWriter io.Writer) port.ChildDriver {
+	return &childDriver{
+		logWriter: logWriter,
+	}
+}
+
+type childDriver struct {
+	logWriter io.Writer
+}
+
+func (d *childDriver) RunChildDriver(opaque map[string]string, quit <-chan struct{}) error {
+	socketPath := opaque[opaquepkg.SocketPath]
+	if socketPath == "" {
+		return errors.New("socket path not set")
+	}
+	childReadyPipePath := opaque[opaquepkg.ChildReadyPipePath]
+	if childReadyPipePath == "" {
+		return errors.New("child ready pipe path not set")
+	}
+	childReadyPipeW, err := os.OpenFile(childReadyPipePath, os.O_WRONLY, os.ModeNamedPipe)
+	if err != nil {
+		return err
+	}
+	ln, err := net.ListenUnix("unix", &net.UnixAddr{
+		Name: socketPath,
+		Net:  "unix",
+	})
+	if err != nil {
+		return err
+	}
+	// write nothing, just close
+	if err = childReadyPipeW.Close(); err != nil {
+		return err
+	}
+	stopAccept := make(chan struct{}, 1)
+	go func() {
+		<-quit
+		stopAccept <- struct{}{}
+		ln.Close()
+	}()
+	for {
+		c, err := ln.AcceptUnix()
+		if err != nil {
+			select {
+			case <-stopAccept:
+				return nil
+			default:
+			}
+			return err
+		}
+		go func() {
+			if rerr := d.routine(c); rerr != nil {
+				rep := msg.Reply{
+					Error: rerr.Error(),
+				}
+				msgutil.MarshalToWriter(c, &rep)
+			}
+			c.Close()
+		}()
+	}
+	return nil
+}
+
+func (d *childDriver) routine(c *net.UnixConn) error {
+	var req msg.Request
+	if _, err := msgutil.UnmarshalFromReader(c, &req); err != nil {
+		return err
+	}
+	switch req.Type {
+	case msg.RequestTypeInit:
+		return d.handleConnectInit(c, &req)
+	case msg.RequestTypeConnect:
+		return d.handleConnectRequest(c, &req)
+	default:
+		return errors.Errorf("unknown request type %q", req.Type)
+	}
+}
+
+func (d *childDriver) handleConnectInit(c *net.UnixConn, req *msg.Request) error {
+	_, err := msgutil.MarshalToWriter(c, nil)
+	return err
+}
+
+func (d *childDriver) handleConnectRequest(c *net.UnixConn, req *msg.Request) error {
+	switch req.Proto {
+	case "tcp":
+	case "udp":
+	default:
+		return errors.Errorf("unknown proto: %q", req.Proto)
+	}
+	var dialer net.Dialer
+	targetConn, err := dialer.Dial(req.Proto, fmt.Sprintf("127.0.0.1:%d", req.Port))
+	if err != nil {
+		return err
+	}
+	defer targetConn.Close() // no effect on duplicated FD
+	targetConnFiler, ok := targetConn.(filer)
+	if !ok {
+		return errors.Errorf("unknown target connection: %+v", targetConn)
+	}
+	targetConnFile, err := targetConnFiler.File()
+	if err != nil {
+		return err
+	}
+	oob := unix.UnixRights(int(targetConnFile.Fd()))
+	f, err := c.File()
+	if err != nil {
+		return err
+	}
+	err = unix.Sendmsg(int(f.Fd()), []byte("dummy"), oob, nil, 0)
+	return err
+}
+
+// filer is implemented by *net.TCPConn and *net.UDPConn
+type filer interface {
+	File() (f *os.File, err error)
+}