1 files changed, 89 insertions, 0 deletions
diff --git a/python/vyos/ifconfig/loopback.py b/python/vyos/ifconfig/loopback.py
new file mode 100644
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+++ b/python/vyos/ifconfig/loopback.py
@@ -0,0 +1,89 @@
+# Copyright 2019 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+
+from vyos.ifconfig.interface import Interface
+
+
+@Interface.register
+class LoopbackIf(Interface):
+    """
+    The loopback device is a special, virtual network interface that your router
+    uses to communicate with itself.
+    """
+    _persistent_addresses = ['127.0.0.1/8', '::1/128']
+    default = {
+        'type': 'loopback',
+    }
+    definition = {
+        **Interface.definition,
+        **{
+            'section': 'loopback',
+            'prefixes': ['lo', ],
+            'bridgeable': True,
+        }
+    }
+
+    name = 'loopback'
+
+    def remove(self):
+        """
+        Loopback interface can not be deleted from operating system. We can
+        only remove all assigned IP addresses.
+
+        Example:
+        >>> from vyos.ifconfig import Interface
+        >>> i = LoopbackIf('lo').remove()
+        """
+        # remove all assigned IP addresses from interface
+        for addr in self.get_addr():
+            if addr in self._persistent_addresses:
+                # Do not allow deletion of the default loopback addresses as
+                # this will cause weird system behavior like snmp/ssh no longer
+                # operating as expected, see https://phabricator.vyos.net/T2034.
+                continue
+
+            self.del_addr(addr)
+
+    def update(self, config):
+        """ General helper function which works on a dictionary retrived by
+        get_config_dict(). It's main intention is to consolidate the scattered
+        interface setup code and provide a single point of entry when workin
+        on any interface. """
+
+        addr = config.get('address', [])
+        # XXX workaround for T2636, convert IP address string to a list
+        # with one element
+        if isinstance(addr, str):
+            addr = [addr]
+
+        # We must ensure that the loopback addresses are never deleted from the system
+        addr += self._persistent_addresses
+
+        # Update IP address entry in our dictionary
+        config.update({'address' : addr})
+
+        # call base class
+        super().update(config)
+
+        # Enable/Disable of an interface must always be done at the end of the
+        # derived class to make use of the ref-counting set_admin_state()
+        # function. We will only enable the interface if 'up' was called as
+        # often as 'down'. This is required by some interface implementations
+        # as certain parameters can only be changed when the interface is
+        # in admin-down state. This ensures the link does not flap during
+        # reconfiguration.
+        state = 'down' if 'disable' in config else 'up'
+        self.set_admin_state(state)