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package server
import (
"bytes"
"fmt"
"io"
"os/exec"
"strings"
"github.com/docker/docker/pkg/pools"
"github.com/kubernetes-incubator/cri-o/oci"
"github.com/sirupsen/logrus"
"golang.org/x/net/context"
pb "k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
)
// PortForward prepares a streaming endpoint to forward ports from a PodSandbox.
func (s *Server) PortForward(ctx context.Context, req *pb.PortForwardRequest) (*pb.PortForwardResponse, error) {
logrus.Debugf("PortForwardRequest %+v", req)
resp, err := s.GetPortForward(req)
if err != nil {
return nil, fmt.Errorf("unable to prepare portforward endpoint")
}
return resp, nil
}
func (ss streamService) PortForward(podSandboxID string, port int32, stream io.ReadWriteCloser) error {
c := ss.runtimeServer.GetSandboxContainer(podSandboxID)
if c == nil {
return fmt.Errorf("could not find container for sandbox %q", podSandboxID)
}
if err := ss.runtimeServer.Runtime().UpdateStatus(c); err != nil {
return err
}
cState := ss.runtimeServer.Runtime().ContainerStatus(c)
if !(cState.Status == oci.ContainerStateRunning || cState.Status == oci.ContainerStateCreated) {
return fmt.Errorf("container is not created or running")
}
containerPid := cState.Pid
socatPath, lookupErr := exec.LookPath("socat")
if lookupErr != nil {
return fmt.Errorf("unable to do port forwarding: socat not found")
}
args := []string{"-t", fmt.Sprintf("%d", containerPid), "-n", socatPath, "-", fmt.Sprintf("TCP4:localhost:%d", port)}
nsenterPath, lookupErr := exec.LookPath("nsenter")
if lookupErr != nil {
return fmt.Errorf("unable to do port forwarding: nsenter not found")
}
commandString := fmt.Sprintf("%s %s", nsenterPath, strings.Join(args, " "))
logrus.Debugf("executing port forwarding command: %s", commandString)
command := exec.Command(nsenterPath, args...)
command.Stdout = stream
stderr := new(bytes.Buffer)
command.Stderr = stderr
// If we use Stdin, command.Run() won't return until the goroutine that's copying
// from stream finishes. Unfortunately, if you have a client like telnet connected
// via port forwarding, as long as the user's telnet client is connected to the user's
// local listener that port forwarding sets up, the telnet session never exits. This
// means that even if socat has finished running, command.Run() won't ever return
// (because the client still has the connection and stream open).
//
// The work around is to use StdinPipe(), as Wait() (called by Run()) closes the pipe
// when the command (socat) exits.
inPipe, err := command.StdinPipe()
if err != nil {
return fmt.Errorf("unable to do port forwarding: error creating stdin pipe: %v", err)
}
go func() {
pools.Copy(inPipe, stream)
inPipe.Close()
}()
if err := command.Run(); err != nil {
return fmt.Errorf("%v: %s", err, stderr.String())
}
return nil
}
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