use 'ping -6' when ping6 is not available

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v0.12.17] - 2023-01-10
+
+### Changed
+- use `ping -6` when `ping6` is not available
+
 ## [v0.12.16] - 2022-11-04
 
 ### Fixed

cmd/.gitignore

@@ -0,0 +1,3 @@
+*
+!.gitignore
+!main.go

src/nettools/ping.go

@@ -2,20 +2,72 @@ package nettools
 
 import (
 	"context"
+	"fmt"
 	"os/exec"
 	"runtime"
+	"strings"
 )
 
 func HasIPv6PingCommand() bool {
+	if hasPing6Command() {
+		return true
+	}
+	if _, err := exec.LookPath("ping"); err == nil {
+		return true
+	}
+	return runtime.GOOS == "windows"
+}
+
+func hasPing6Command() bool {
 	_, err := exec.LookPath("ping6")
-	return err == nil || runtime.GOOS == "windows"
+	return err == nil
 }
 
 func Ping(ctx context.Context, address string) error {
-	pingCommand := exec.CommandContext(ctx, "ping6", "-c", "1", address)
+	cmd := []string{"ping6", "-c", "1", address}
+	if !hasPing6Command() {
+		cmd = []string{"ping", "-6", "-c", "1", address}
+	}
 	if runtime.GOOS == "windows" {
-		pingCommand = exec.CommandContext(ctx, "ping", "/n", "1", address)
+		cmd = []string{"ping", "/n", "1", address}
 	}
 
-	return pingCommand.Run()
+	if out, err := exec.CommandContext(ctx, cmd[0], cmd[1:]...).Output(); err != nil {
+		return pingError(err, cmd, out)
+	}
+	return nil
+}
+
+type PingError struct {
+	err    error
+	cmd    []string
+	output string
+}
+
+func (p PingError) Err() error {
+	return p.err
+}
+
+func (p PingError) Output() string {
+	return p.output
+}
+
+func (p PingError) Cmd() string {
+	return strings.Join(p.cmd, " ")
+}
+
+func (p PingError) Error() string {
+	return fmt.Sprintf("ping => err: %s, exec: %s, output: %s", p.err, p.Cmd(), p.output)
+}
+
+func pingError(
+	err error,
+	cmd []string,
+	output []byte,
+) error {
+	return PingError{
+		err:    err,
+		cmd:    cmd,
+		output: string(output),
+	}
 }

src/vpn/dnsIsAlive.go

@@ -18,6 +18,7 @@ func (h *Handler) dnsIsAlive() (bool, error) {
 	}
 	err := nettools.Ping(ctx, "node1.master.core.zerops")
 	if err != nil {
+		h.logger.Error(err)
 		return false, nil
 	}
 	return true, nil

src/vpn/isVpnTunnelAlive.go

@@ -20,6 +20,7 @@ func (h *Handler) isVpnTunnelAlive(ctx context.Context, serverIp net.IP) bool {
 
 			err := nettools.Ping(ctx, serverIp.String())
 			if err != nil {
+				h.logger.Error(err)
 				return false
 			}
 			return true