tunnel: T5879: properly verify source-interface used for tunnels

A tunnel interface can not properly be sourced from a pppoe0 interface when
such interface is not (yet) connected to the BRAS. It might work on a running
system, but subsequent reboots will fail as the source-interface most likely
does not yet exist.

2 files changed, 18 insertions, 2 deletions

diff --git a/smoketest/scripts/cli/test_interfaces_tunnel.py b/smoketest/scripts/cli/test_interfaces_tunnel.py
index 2a7a519fd..dd9f1d2d1 100755
--- a/smoketest/scripts/cli/test_interfaces_tunnel.py
+++ b/smoketest/scripts/cli/test_interfaces_tunnel.py
@@ -393,5 +393,21 @@ class TunnelInterfaceTest(BasicInterfaceTest.TestCase):
             self.assertEqual(tunnel_config['encapsulation'],    conf['linkinfo']['info_kind'])
             self.assertEqual(tunnel_config['remote'],           conf['linkinfo']['info_data']['remote'])
 
+    def test_tunnel_invalid_source_interface(self):
+        encapsulation = 'gre'
+        remote = '192.0.2.1'
+        interface = 'tun7543'
+
+        self.cli_set(self._base_path + [interface, 'encapsulation', encapsulation])
+        self.cli_set(self._base_path + [interface, 'remote', remote])
+
+        for dynamic_interface in ['l2tp0', 'ppp4220', 'sstpc0', 'ipoe654']:
+            self.cli_set(self._base_path + [interface, 'source-interface', dynamic_interface])
+            # verify() - we can not source from dynamic interfaces
+            with self.assertRaises(ConfigSessionError):
+                self.cli_commit()
+        self.cli_set(self._base_path + [interface, 'source-interface', 'eth0'])
+        self.cli_commit()
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/src/conf_mode/interfaces_tunnel.py b/src/conf_mode/interfaces_tunnel.py
index 91aed9cc3..efa5ebc64 100755
--- a/src/conf_mode/interfaces_tunnel.py
+++ b/src/conf_mode/interfaces_tunnel.py
@@ -24,7 +24,7 @@ from vyos.configdict import get_interface_dict
 from vyos.configdict import is_node_changed
 from vyos.configverify import verify_address
 from vyos.configverify import verify_bridge_delete
-from vyos.configverify import verify_interface_exists
+from vyos.configverify import verify_source_interface
 from vyos.configverify import verify_mtu_ipv6
 from vyos.configverify import verify_mirror_redirect
 from vyos.configverify import verify_vrf
@@ -166,7 +166,7 @@ def verify(tunnel):
     verify_mirror_redirect(tunnel)
 
     if 'source_interface' in tunnel:
-        verify_interface_exists(tunnel['source_interface'])
+        verify_source_interface(tunnel)
 
     # TTL != 0 and nopmtudisc are incompatible, parameters and ip use default
     # values, thus the keys are always present.