migrate to golang.zx2c4.com/wireguard/wgctrl (#239)

* migrate to golang.zx2c4.com/wireguard/wgctrl

This commit introduces the usage of wgctrl.
It avoids the usage of exec calls of the wg command
and parsing the output of `wg show`.

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* vendor wgctrl

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* apply suggestions from code review

Remove wireguard.Enpoint struct and use net.UDPAddr for the resolved
endpoint and addr string (dnsanme:port) if a DN was supplied.

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* pkg/*: use wireguard.Enpoint

This commit introduces the wireguard.Enpoint struct.
It encapsulates a DN name with port and a net.UPDAddr.
The fields are private and only accessible over exported Methods
to avoid accidental modification.

Also iptables.GetProtocol is improved to avoid ipv4 rules being applied
by `ip6tables`.

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* pkg/wireguard/conf_test.go: add tests for Endpoint

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* cmd/kg/main.go: validate port range

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* add suggestions from review

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* pkg/mesh/mesh.go: use Equal func

Implement an Equal func for Enpoint and use it instead of comparing
strings.

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* cmd/kgctl/main.go: check port range

Signed-off-by: leonnicolas <leonloechner@gmx.de>

* vendor

Signed-off-by: leonnicolas <leonloechner@gmx.de>

pkg/wireguard/wireguard.go

@@ -18,9 +18,7 @@
 package wireguard
 
 import (
-	"bytes"
 	"fmt"
-	"os/exec"
 
 	"github.com/vishvananda/netlink"
 )
@@ -65,74 +63,3 @@ func New(name string, mtu uint) (int, bool, error) {
 	}
 	return link.Attrs().Index, true, nil
 }
-
-// Keys generates a WireGuard private and public key-pair.
-func Keys() ([]byte, []byte, error) {
-	private, err := GenKey()
-	if err != nil {
-		return nil, nil, fmt.Errorf("failed to generate private key: %v", err)
-	}
-	public, err := PubKey(private)
-	return private, public, err
-}
-
-// GenKey generates a WireGuard private key.
-func GenKey() ([]byte, error) {
-	key, err := exec.Command("wg", "genkey").Output()
-	return bytes.Trim(key, "\n"), err
-}
-
-// PubKey generates a WireGuard public key for a given private key.
-func PubKey(key []byte) ([]byte, error) {
-	cmd := exec.Command("wg", "pubkey")
-	stdin, err := cmd.StdinPipe()
-	if err != nil {
-		return nil, fmt.Errorf("failed to open pipe to stdin: %v", err)
-	}
-
-	go func() {
-		defer stdin.Close()
-		stdin.Write(key)
-	}()
-
-	public, err := cmd.Output()
-	if err != nil {
-		return nil, fmt.Errorf("failed to generate public key: %v", err)
-	}
-	return bytes.Trim(public, "\n"), nil
-}
-
-// SetConf applies a WireGuard configuration file to the given interface.
-func SetConf(iface string, path string) error {
-	cmd := exec.Command("wg", "setconf", iface, path)
-	var stderr bytes.Buffer
-	cmd.Stderr = &stderr
-	if err := cmd.Run(); err != nil {
-		return fmt.Errorf("failed to apply the WireGuard configuration: %s", stderr.String())
-	}
-	return nil
-}
-
-// ShowConf gets the WireGuard configuration for the given interface.
-func ShowConf(iface string) ([]byte, error) {
-	cmd := exec.Command("wg", "showconf", iface)
-	var stderr, stdout bytes.Buffer
-	cmd.Stderr = &stderr
-	cmd.Stdout = &stdout
-	if err := cmd.Run(); err != nil {
-		return nil, fmt.Errorf("failed to read the WireGuard configuration: %s", stderr.String())
-	}
-	return stdout.Bytes(), nil
-}
-
-// ShowDump gets the WireGuard configuration and runtime information for the given interface.
-func ShowDump(iface string) ([]byte, error) {
-	cmd := exec.Command("wg", "show", iface, "dump")
-	var stderr, stdout bytes.Buffer
-	cmd.Stderr = &stderr
-	cmd.Stdout = &stdout
-	if err := cmd.Run(); err != nil {
-		return nil, fmt.Errorf("failed to read the WireGuard dump output: %s", stderr.String())
-	}
-	return stdout.Bytes(), nil
-}