adds show command

cmd/root.go

@@ -84,6 +84,22 @@ var syncCmd = &cobra.Command{
 	},
 }
 
+var showCmd = &cobra.Command{
+	Use:   "show [interface]",
+	Short: "Show current configuration",
+	Args:  cobra.MaximumNArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+		device := ""
+		if len(args) == 1 {
+			device = args[0]
+		}
+
+		if err := wgquick.Show(device); err != nil {
+			logrus.WithError(err).Errorln("cannot show configuration")
+		}
+	},
+}
+
 func loadConfig(cfg string) (*wgquick.Config, logrus.FieldLogger) {
 	log := logrus.WithField("iface", iface)
 	_, err := os.Stat(cfg)
@@ -133,6 +149,7 @@ func init() {
 	rootCmd.AddCommand(downCmd)
 	rootCmd.AddCommand(syncCmd)
 	rootCmd.AddCommand(versionCmd)
+	rootCmd.AddCommand(showCmd)
 }
 
 func Execute() {

wgquick/show.go

@@ -0,0 +1,93 @@
+// Mostly taken from: https://github.com/WireGuard/wgctrl-go/blob/master/cmd/wgctrl/main.go
+//
+// nolint: forbidigo, godox
+package wgquick
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"golang.zx2c4.com/wireguard/wgctrl"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+func Show(iface string) error {
+	c, err := wgctrl.New()
+	if err != nil {
+		return fmt.Errorf("failed to open wgctrl: %w", err)
+	}
+	defer c.Close()
+
+	var devices []*wgtypes.Device
+
+	if iface != "" {
+		d, err := c.Device(iface)
+		if err != nil {
+			return fmt.Errorf("failed to get device %s: %w", iface, err)
+		}
+
+		devices = append(devices, d)
+	} else {
+		devices, err = c.Devices()
+		if err != nil {
+			return fmt.Errorf("failed to get devices: %w", err)
+		}
+	}
+
+	for _, d := range devices {
+		printDevice(d)
+
+		for _, p := range d.Peers {
+			printPeer(p)
+		}
+	}
+
+	return nil
+}
+
+func printDevice(d *wgtypes.Device) {
+	const f = `interface: %s (%s)
+  public key: %s
+  private key: (hidden)
+  listening port: %d
+
+`
+
+	fmt.Printf(
+		f,
+		d.Name,
+		d.Type.String(),
+		d.PublicKey.String(),
+		d.ListenPort)
+}
+
+func printPeer(p wgtypes.Peer) {
+	const f = `peer: %s
+  endpoint: %s
+  allowed ips: %s
+  latest handshake: %s
+  transfer: %d B received, %d B sent
+
+`
+
+	fmt.Printf(
+		f,
+		p.PublicKey.String(),
+		// TODO(mdlayher): get right endpoint with getnameinfo.
+		p.Endpoint.String(),
+		ipsString(p.AllowedIPs),
+		p.LastHandshakeTime.String(),
+		p.ReceiveBytes,
+		p.TransmitBytes,
+	)
+}
+
+func ipsString(ipns []net.IPNet) string {
+	ss := make([]string, 0, len(ipns))
+	for _, ipn := range ipns {
+		ss = append(ss, ipn.String())
+	}
+
+	return strings.Join(ss, ", ")
+}