vyos.ifconfig: provide generic get_mac_synthetic() method

WireGuard, Tunnel and also PPPoE all need a ways to calculate a synthetic MAC
address used for the EUI64 link-local addresses. Instead of copying the code
from Tunnel to WireGuard to PPPoE, use a generic implementation.

(cherry picked from commit b7d30137b17da49ed5099d4d96659b363fc7bcc9)

3 files changed, 33 insertions, 49 deletions

diff --git a/python/vyos/ifconfig/interface.py b/python/vyos/ifconfig/interface.py
index 9c02af68f..e815c0129 100644
--- a/python/vyos/ifconfig/interface.py
+++ b/python/vyos/ifconfig/interface.py
@@ -52,6 +52,10 @@ from vyos.ifconfig.vrrp import VRRP
 from vyos.ifconfig.operational import Operational
 from vyos.ifconfig import Section
 
+from netaddr import EUI
+from netaddr import mac_unix_expanded
+from random import getrandbits
+
 class Interface(Control):
     # This is the class which will be used to create
     # self.operational, it allows subclasses, such as
@@ -367,6 +371,31 @@ class Interface(Control):
         """
         return self.get_interface('mac')
 
+    def get_mac_synthetic(self):
+        """
+        Get a synthetic MAC address. This is a common method which can be called
+        from derived classes to overwrite the get_mac() call in a generic way.
+
+        NOTE: Tunnel interfaces have no "MAC" address by default. The content
+              of the 'address' file in /sys/class/net/device contains the
+              local-ip thus we generate a random MAC address instead
+
+        Example:
+        >>> from vyos.ifconfig import Interface
+        >>> Interface('eth0').get_mac()
+        '00:50:ab:cd:ef:00'
+        """
+        # we choose 40 random bytes for the MAC address, this gives
+        # us e.g. EUI('00-EA-EE-D6-A3-C8') or EUI('00-41-B9-0D-F2-2A')
+        tmp = EUI(getrandbits(48)).value
+        # set locally administered bit in MAC address
+        tmp |= 0xf20000000000
+        # convert integer to "real" MAC address representation
+        mac = EUI(hex(tmp).split('x')[-1])
+        # change dialect to use : as delimiter instead of -
+        mac.dialect = mac_unix_expanded
+        return str(mac)
+
     def set_mac(self, mac):
         """
         Set interface MAC (Media Access Contrl) address to given value.
diff --git a/python/vyos/ifconfig/tunnel.py b/python/vyos/ifconfig/tunnel.py
index e40756cc7..5258a2cb1 100644
--- a/python/vyos/ifconfig/tunnel.py
+++ b/python/vyos/ifconfig/tunnel.py
@@ -16,10 +16,6 @@
 # https://developers.redhat.com/blog/2019/05/17/an-introduction-to-linux-virtual-interfaces-tunnels/
 # https://community.hetzner.com/tutorials/linux-setup-gre-tunnel
 
-from netaddr import EUI
-from netaddr import mac_unix_expanded
-from random import getrandbits
-
 from vyos.ifconfig.interface import Interface
 from vyos.util import dict_search
 from vyos.validate import assert_list
@@ -163,26 +159,8 @@ class TunnelIf(Interface):
         self._cmd(cmd.format(**self.config))
 
     def get_mac(self):
-        """
-        Get current interface MAC (Media Access Contrl) address used.
-        NOTE: Tunnel interfaces have no "MAC" address by default. The content
-              of the 'address' file in /sys/class/net/device contains the
-              local-ip thus we generate a random MAC address instead
-        Example:
-        >>> from vyos.ifconfig import Interface
-        >>> Interface('eth0').get_mac()
-        '00:50:ab:cd:ef:00'
-        """
-        # we choose 40 random bytes for the MAC address, this gives
-        # us e.g. EUI('00-EA-EE-D6-A3-C8') or EUI('00-41-B9-0D-F2-2A')
-        tmp = EUI(getrandbits(48)).value
-        # set locally administered bit in MAC address
-        tmp |= 0xf20000000000
-        # convert integer to "real" MAC address representation
-        mac = EUI(hex(tmp).split('x')[-1])
-        # change dialect to use : as delimiter instead of -
-        mac.dialect = mac_unix_expanded
-        return str(mac)
+        """ Get a synthetic MAC address. """
+        return self.get_mac_synthetic()
 
     def update(self, config):
         """ General helper function which works on a dictionary retrived by
diff --git a/python/vyos/ifconfig/wireguard.py b/python/vyos/ifconfig/wireguard.py
index 2d2243b84..de1b56ce5 100644
--- a/python/vyos/ifconfig/wireguard.py
+++ b/python/vyos/ifconfig/wireguard.py
@@ -17,9 +17,6 @@ import os
 import time
 
 from datetime import timedelta
-from netaddr import EUI
-from netaddr import mac_unix_expanded
-from random import getrandbits
 
 from hurry.filesize import size
 from hurry.filesize import alternative
@@ -163,28 +160,8 @@ class WireGuardIf(Interface):
          'allowed_ips', 'fwmark', 'endpoint', 'keepalive']
 
     def get_mac(self):
-        """
-        Get current interface MAC (Media Access Contrl) address used.
-
-        NOTE: Tunnel interfaces have no "MAC" address by default. The content
-              of the 'address' file in /sys/class/net/device contains the
-              local-ip thus we generate a random MAC address instead
-
-        Example:
-        >>> from vyos.ifconfig import Interface
-        >>> Interface('eth0').get_mac()
-        '00:50:ab:cd:ef:00'
-        """
-        # we choose 40 random bytes for the MAC address, this gives
-        # us e.g. EUI('00-EA-EE-D6-A3-C8') or EUI('00-41-B9-0D-F2-2A')
-        tmp = EUI(getrandbits(48)).value
-        # set locally administered bit in MAC address
-        tmp |= 0xf20000000000
-        # convert integer to "real" MAC address representation
-        mac = EUI(hex(tmp).split('x')[-1])
-        # change dialect to use : as delimiter instead of -
-        mac.dialect = mac_unix_expanded
-        return str(mac)
+        """ Get a synthetic MAC address. """
+        return self.get_mac_synthetic()
 
     def update(self, config):
         """ General helper function which works on a dictionary retrived by