k3s/pkg/agent/netpol/utils/iptables.go

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// Apache License v2.0 (copyright Cloud Native Labs & Rancher Labs)
// - modified from https://github.com/cloudnativelabs/kube-router/blob/73b1b03b32c5755b240f6c077bb097abe3888314/pkg/utils/iptables.go
package utils
import (
"bytes"
"fmt"
"os/exec"
"strings"
)
var hasWait bool
func init() {
path, err := exec.LookPath("iptables-restore")
if err != nil {
return
}
args := []string{"iptables-restore", "--help"}
cmd := exec.Cmd{
Path: path,
Args: args,
}
cmdOutput, err := cmd.CombinedOutput()
if err != nil {
return
}
hasWait = strings.Contains(string(cmdOutput), "wait")
}
// SaveInto calls `iptables-save` for given table and stores result in a given buffer.
func SaveInto(table string, buffer *bytes.Buffer) error {
path, err := exec.LookPath("iptables-save")
if err != nil {
return err
}
stderrBuffer := bytes.NewBuffer(nil)
args := []string{"iptables-save", "-t", table}
cmd := exec.Cmd{
Path: path,
Args: args,
Stdout: buffer,
Stderr: stderrBuffer,
}
if err := cmd.Run(); err != nil {
return fmt.Errorf("%v (%s)", err, stderrBuffer)
}
return nil
}
// Restore runs `iptables-restore` passing data through []byte.
func Restore(table string, data []byte) error {
path, err := exec.LookPath("iptables-restore")
if err != nil {
return err
}
var args []string
if hasWait {
args = []string{"iptables-restore", "--wait", "-T", table}
} else {
args = []string{"iptables-restore", "-T", table}
}
cmd := exec.Cmd{
Path: path,
Args: args,
Stdin: bytes.NewBuffer(data),
}
b, err := cmd.CombinedOutput()
if err != nil {
return fmt.Errorf("%v (%s)", err, b)
}
return nil
}