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87 lines
2.6 KiB
Go
87 lines
2.6 KiB
Go
// +build !windows,!dockerless
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/*
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Copyright 2019 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package dockershim
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import (
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"bytes"
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"fmt"
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"io"
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"os/exec"
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"strings"
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"k8s.io/klog/v2"
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)
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func (r *streamingRuntime) portForward(podSandboxID string, port int32, stream io.ReadWriteCloser) error {
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container, err := r.client.InspectContainer(podSandboxID)
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if err != nil {
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return err
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}
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if !container.State.Running {
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return fmt.Errorf("container not running (%s)", container.ID)
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}
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containerPid := container.State.Pid
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socatPath, lookupErr := exec.LookPath("socat")
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if lookupErr != nil {
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return fmt.Errorf("unable to do port forwarding: socat not found")
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}
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args := []string{"-t", fmt.Sprintf("%d", containerPid), "-n", socatPath, "-", fmt.Sprintf("TCP4:localhost:%d", port)}
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nsenterPath, lookupErr := exec.LookPath("nsenter")
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if lookupErr != nil {
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return fmt.Errorf("unable to do port forwarding: nsenter not found")
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}
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commandString := fmt.Sprintf("%s %s", nsenterPath, strings.Join(args, " "))
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klog.V(4).Infof("executing port forwarding command: %s", commandString)
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command := exec.Command(nsenterPath, args...)
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command.Stdout = stream
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stderr := new(bytes.Buffer)
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command.Stderr = stderr
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// If we use Stdin, command.Run() won't return until the goroutine that's copying
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// from stream finishes. Unfortunately, if you have a client like telnet connected
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// via port forwarding, as long as the user's telnet client is connected to the user's
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// local listener that port forwarding sets up, the telnet session never exits. This
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// means that even if socat has finished running, command.Run() won't ever return
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// (because the client still has the connection and stream open).
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//
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// The work around is to use StdinPipe(), as Wait() (called by Run()) closes the pipe
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// when the command (socat) exits.
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inPipe, err := command.StdinPipe()
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if err != nil {
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return fmt.Errorf("unable to do port forwarding: error creating stdin pipe: %v", err)
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}
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go func() {
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io.Copy(inPipe, stream)
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inPipe.Close()
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}()
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if err := command.Run(); err != nil {
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return fmt.Errorf("%v: %s", err, stderr.String())
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}
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return nil
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}
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