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tap.go
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tap.go
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package ovs
import (
"fmt"
"os"
"path/filepath"
log "github.com/Sirupsen/logrus"
)
// tapTemplate is the NetDev file template for a TAP interface
var tapTemplate = `
[NetDev]
Name=%s
Kind=tap
[Tap]
`
// netDevDir is the directory systemd-networkd checks for new interface definitions
var netDevDir = "/etc/systemd/network"
// netDevFilepath builds the full path for a NetDev file
func netDevFilepath(ifaceName string) string {
return filepath.Join(netDevDir, fmt.Sprintf("%s.netdev", ifaceName))
}
// createTAPIface creates a new TAP interface
func createTAPIface(ifaceName string) error {
filepath := netDevFilepath(ifaceName)
// Create the netdev file
file, err := os.Create(filepath)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"filepath": filepath,
}).Error("failed to create netdev file")
return err
}
defer file.Close()
// Populate the file from the template. If there's a problem, clean up
contents := fmt.Sprintf(tapTemplate, ifaceName)
_, err = file.Write([]byte(contents))
if err != nil {
log.WithFields(log.Fields{
"error": err,
"filepath": filepath,
"contents": contents,
}).Error("failed to write netdev file")
_ = os.Remove(filepath)
return err
}
// Restart networkd so changes take effect
return restartNetworkd()
}
// deleteTAPIface removes a TAP interface
func deleteTAPIface(ifaceName string) error {
filepath := netDevFilepath(ifaceName)
// Remove netdev file
if err := os.Remove(filepath); err != nil && !os.IsNotExist(err) {
log.WithFields(log.Fields{
"error": err,
"filepath": filepath,
}).Error("failed to remove netdev file")
return err
}
// Remove the interface
cmd := command{command: "ip"}
args := []string{
"link",
"delete",
ifaceName,
}
if _, err := cmd.Run(args...); err != nil {
return err
}
// Restart networkd so changes take effect
return restartNetworkd()
}
// restartNetworkd restarts systemd-networkd
func restartNetworkd() error {
cmd := command{command: "systemctl"}
_, err := cmd.Run("restart", "systemd-networkd")
if err != nil {
return err
}
return nil
}