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utils(iptables): Factor out a common function for executing commands #1277

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utils(iptables): Factor out a common function for executing commands #1277

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43 changes: 20 additions & 23 deletions pkg/utils/iptables.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,49 +27,46 @@ func init() {
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")
// iptablesExec contains the common logic for calling save and restore
// commands.
func iptablesExec(cmdName string, args []string, data []byte, stdoutBuffer *bytes.Buffer) error {
path, err := exec.LookPath(cmdName)
if err != nil {
return err
}
stderrBuffer := bytes.NewBuffer(nil)
args := []string{"iptables-save", "-t", table}
cmd := exec.Cmd{
Path: path,
Args: args,
Stdout: buffer,
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Collaborator

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The args here needs to contain the command name here as well.

So you'll need to do some work like the following in order for it to work:

trueArgs := append([]string{cmdName}, args...)

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Whoops, sorry for that!. Should be fixed now.

Args: append([]string{cmdName}, args...),
Stderr: stderrBuffer,
}
if data != nil {
cmd.Stdin = bytes.NewBuffer(data)
}
if stdoutBuffer != nil {
cmd.Stdout = stdoutBuffer
}
if err := cmd.Run(); err != nil {
return fmt.Errorf("%v (%s)", err, stderrBuffer)
return fmt.Errorf("failed to call %s %v: %w, (%s)", cmdName, args, err, stderrBuffer.String())
}
return nil
}

// SaveInto calls `iptables-save` for given table and stores result in a given buffer.
func SaveInto(table string, buffer *bytes.Buffer) error {
return iptablesExec("iptables-save", []string{"-t", table}, nil, buffer)
}

// 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}
args = []string{"--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)
args = []string{"-T", table}
}

return nil
return iptablesExec("iptables-restore", args, data, nil)
}

// AppendUnique ensures that rule is in chain only once in the buffer and that the occurrence is at the end of the
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