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channel.go
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channel.go
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//
// Copyright (c) 2017 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
//
package main
import (
"fmt"
"io/ioutil"
"net"
"os"
"path/filepath"
"strings"
"github.com/hashicorp/yamux"
"github.com/mdlayher/vsock"
"golang.org/x/sys/unix"
)
type channel interface {
setup() error
listen() (net.Listener, error)
teardown() error
}
func newChannel() (channel, error) {
// Check for vsock support.
vSockSupported, err := isAFVSockSupported()
if err != nil {
return nil, err
}
if vSockSupported {
// Check if vsock socket exists. We want to cover the case
// where the guest OS can support vsock, but the runtime is
// still using virtio serial connection.
exist, err := vSockPathExist()
if err != nil {
return nil, err
}
if exist {
return &vSockChannel{}, nil
}
}
return &serialChannel{}, nil
}
type vSockChannel struct {
}
func (c *vSockChannel) setup() error {
return nil
}
func (c *vSockChannel) listen() (net.Listener, error) {
l, err := vsock.Listen(vSockPort)
if err != nil {
return nil, err
}
return l, nil
}
func (c *vSockChannel) teardown() error {
return nil
}
type serialChannel struct {
serialConn *os.File
}
func (c *serialChannel) setup() error {
// Open serial channel.
file, err := openSerialChannel()
if err != nil {
return err
}
c.serialConn = file
return nil
}
func (c *serialChannel) listen() (net.Listener, error) {
// Initialize Yamux server.
session, err := yamux.Server(c.serialConn, nil)
if err != nil {
return nil, err
}
return session, nil
}
func (c *serialChannel) teardown() error {
return c.serialConn.Close()
}
func isAFVSockSupported() (bool, error) {
fd, err := unix.Socket(unix.AF_VSOCK, unix.SOCK_STREAM, 0)
if err != nil {
// This case is valid. It means AF_VSOCK is not a supported
// domain on this system.
if err == unix.EAFNOSUPPORT {
return false, nil
}
return false, err
}
if err := unix.Close(fd); err != nil {
return true, err
}
return true, nil
}
func vSockPathExist() (bool, error) {
if _, err := os.Stat(vSockDevPath); err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, err
}
return true, nil
}
func findVirtualSerialPath(serialName string) (string, error) {
dir, err := os.Open(virtIOPath)
if err != nil {
return "", err
}
defer dir.Close()
ports, err := dir.Readdirnames(0)
if err != nil {
return "", err
}
for _, port := range ports {
path := filepath.Join(virtIOPath, port, "name")
content, err := ioutil.ReadFile(path)
if err != nil {
if os.IsNotExist(err) {
agentLog.WithField("file", path).Debug("Skip parsing of non-existent file")
continue
}
return "", err
}
if strings.Contains(string(content), serialName) == true {
return filepath.Join(devRootPath, port), nil
}
}
return "", fmt.Errorf("Could not find virtio port %s", serialName)
}
func openSerialChannel() (*os.File, error) {
serialPath, err := findVirtualSerialPath(serialChannelName)
if err != nil {
return nil, err
}
file, err := os.OpenFile(serialPath, os.O_RDWR, os.ModeDevice)
if err != nil {
return nil, err
}
return file, nil
}