wireguard: fix KeyPair.Validate()

PrivateKey and PublicKey are now fixed length arrays,
so testing for len 0 is invalid

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/wireguard/keys.go

@@ -183,20 +183,14 @@ type KeyPair struct {
 // Validate checks the PublicKey matches the PrivateKey,
 // and sets the PublicKey if missing
 func (kp *KeyPair) Validate() error {
-	keyLen := len(kp.PrivateKey)
-	pubLen := len(kp.PublicKey)
-
 	switch {
-	case keyLen != PrivateKeySize:
+	case kp.PrivateKey.IsZero():
-		// bad private key
+		// no private key
 		return ErrInvalidPrivateKey
-	case pubLen == 0:
+	case kp.PublicKey.IsZero():
 		// no public key, set it
 		kp.PublicKey = kp.PrivateKey.Public()
 		return nil
-	case pubLen != PublicKeySize:
-		// bad public key
-		return ErrInvalidPublicKey
 	case !kp.PrivateKey.Public().Equal(kp.PublicKey):
 		// wrong public key
 		return ErrInvalidPublicKey