pppoe: T5630: make MRU default to MTU if unspecified

This fixes the implementation in e062a8c11 ("pppoe: T5630: allow to specify MRU
in addition to already configurable MTU") and restores the bahavior that MRU
defaults to MTU if MRU is not explicitly set.

This was the behavior in VyOS 1.3.3 and below before we added ability to define
the MRU value.

(cherry picked from commit ffd7339e2ea3eafdd97ac0763ca4a3913fe71bf3)

3 files changed, 60 insertions, 16 deletions

diff --git a/interface-definitions/interfaces-pppoe.xml.in b/interface-definitions/interfaces-pppoe.xml.in
index 30fcb8573..4542b8b01 100644
--- a/interface-definitions/interfaces-pppoe.xml.in
+++ b/interface-definitions/interfaces-pppoe.xml.in
@@ -111,7 +111,7 @@
           </leafNode>
           <leafNode name="mru">
             <properties>
-              <help>Maximum Receive Unit (MRU)</help>
+              <help>Maximum Receive Unit (MRU) (default: MTU value)</help>
               <valueHelp>
                 <format>u32:128-16384</format>
                 <description>Maximum Receive Unit in byte</description>
@@ -121,7 +121,6 @@
               </constraint>
               <constraintErrorMessage>MRU must be between 128 and 16384</constraintErrorMessage>
             </properties>
-            <defaultValue>1492</defaultValue>
           </leafNode>
           #include <include/interface/no-peer-dns.xml.i>
           <leafNode name="remote-address">
diff --git a/smoketest/scripts/cli/test_interfaces_pppoe.py b/smoketest/scripts/cli/test_interfaces_pppoe.py
index 7b702759f..e99d8b3d1 100755
--- a/smoketest/scripts/cli/test_interfaces_pppoe.py
+++ b/smoketest/scripts/cli/test_interfaces_pppoe.py
@@ -36,6 +36,9 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
     @classmethod
     def setUpClass(cls):
         super(PPPoEInterfaceTest, cls).setUpClass()
+        # ensure we can also run this test on a live system - so lets clean
+        # out the current configuration :)
+        cls.cli_delete(cls, base_path)
 
         cls._interfaces = ['pppoe10', 'pppoe20', 'pppoe30']
         cls._source_interface = 'eth0'
@@ -53,18 +56,16 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
         self.cli_delete(base_path)
         self.cli_commit()
 
-    def test_01_pppoe_client(self):
+    def test_pppoe_client(self):
         # Check if PPPoE dialer can be configured and runs
         for interface in self._interfaces:
             user = f'VyOS-user-{interface}'
             passwd = f'VyOS-passwd-{interface}'
             mtu = '1400'
-            mru = '1300'
 
             self.cli_set(base_path + [interface, 'authentication', 'username', user])
             self.cli_set(base_path + [interface, 'authentication', 'password', passwd])
             self.cli_set(base_path + [interface, 'mtu', mtu])
-            self.cli_set(base_path + [interface, 'mru', '9000'])
             self.cli_set(base_path + [interface, 'no-peer-dns'])
 
             # check validate() - a source-interface is required
@@ -72,11 +73,6 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
                 self.cli_commit()
             self.cli_set(base_path + [interface, 'source-interface', self._source_interface])
 
-            # check validate() - MRU needs to be less or equal then MTU
-            with self.assertRaises(ConfigSessionError):
-                self.cli_commit()
-            self.cli_set(base_path + [interface, 'mru', mru])
-
         # commit changes
         self.cli_commit()
 
@@ -87,8 +83,9 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
 
             tmp = get_config_value(interface, 'mtu')[1]
             self.assertEqual(tmp, mtu)
+            # MRU must default to MTU if not specified on CLI
             tmp = get_config_value(interface, 'mru')[1]
-            self.assertEqual(tmp, mru)
+            self.assertEqual(tmp, mtu)
             tmp = get_config_value(interface, 'user')[1].replace('"', '')
             self.assertEqual(tmp, user)
             tmp = get_config_value(interface, 'password')[1].replace('"', '')
@@ -96,7 +93,7 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
             tmp = get_config_value(interface, 'ifname')[1]
             self.assertEqual(tmp, interface)
 
-    def test_02_pppoe_client_disabled_interface(self):
+    def test_pppoe_client_disabled_interface(self):
         # Check if PPPoE Client can be disabled
         for interface in self._interfaces:
             user = f'VyOS-user-{interface}'
@@ -125,16 +122,16 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
         self.cli_commit()
 
 
-    def test_03_pppoe_authentication(self):
+    def test_pppoe_authentication(self):
         # When username or password is set - so must be the other
         for interface in self._interfaces:
             user = f'VyOS-user-{interface}'
             passwd = f'VyOS-passwd-{interface}'
 
-            self.cli_set(base_path + [interface, 'authentication', 'username', user])
             self.cli_set(base_path + [interface, 'source-interface', self._source_interface])
             self.cli_set(base_path + [interface, 'ipv6', 'address', 'autoconf'])
 
+            self.cli_set(base_path + [interface, 'authentication', 'username', user])
             # check validate() - if user is set, so must be the password
             with self.assertRaises(ConfigSessionError):
                 self.cli_commit()
@@ -143,7 +140,7 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
 
         self.cli_commit()
 
-    def test_04_pppoe_dhcpv6pd(self):
+    def test_pppoe_dhcpv6pd(self):
         # Check if PPPoE dialer can be configured with DHCPv6-PD
         address = '1'
         sla_id = '0'
@@ -183,7 +180,7 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
             tmp = get_config_value(interface, '+ipv6 ipv6cp-use-ipaddr')
             self.assertListEqual(tmp, ['+ipv6', 'ipv6cp-use-ipaddr'])
 
-    def test_05_pppoe_options(self):
+    def test_pppoe_options(self):
         # Check if PPPoE dialer can be configured with DHCPv6-PD
         for interface in self._interfaces:
             user = f'VyOS-user-{interface}'
@@ -215,5 +212,47 @@ class PPPoEInterfaceTest(VyOSUnitTestSHIM.TestCase):
             tmp = get_config_value(interface, 'pppoe-host-uniq')[1]
             self.assertEqual(tmp, f'"{host_uniq}"')
 
+    def test_pppoe_mtu_mru(self):
+        # Check if PPPoE dialer can be configured and runs
+        for interface in self._interfaces:
+            user = f'VyOS-user-{interface}'
+            passwd = f'VyOS-passwd-{interface}'
+            mtu = '1400'
+            mru = '1300'
+
+            self.cli_set(base_path + [interface, 'authentication', 'username', user])
+            self.cli_set(base_path + [interface, 'authentication', 'password', passwd])
+            self.cli_set(base_path + [interface, 'mtu', mtu])
+            self.cli_set(base_path + [interface, 'mru', '9000'])
+
+            # check validate() - a source-interface is required
+            with self.assertRaises(ConfigSessionError):
+                self.cli_commit()
+            self.cli_set(base_path + [interface, 'source-interface', self._source_interface])
+
+            # check validate() - MRU needs to be less or equal then MTU
+            with self.assertRaises(ConfigSessionError):
+                self.cli_commit()
+            self.cli_set(base_path + [interface, 'mru', mru])
+
+        # commit changes
+        self.cli_commit()
+
+        # verify configuration file(s)
+        for interface in self._interfaces:
+            user = f'VyOS-user-{interface}'
+            passwd = f'VyOS-passwd-{interface}'
+
+            tmp = get_config_value(interface, 'mtu')[1]
+            self.assertEqual(tmp, mtu)
+            tmp = get_config_value(interface, 'mru')[1]
+            self.assertEqual(tmp, mru)
+            tmp = get_config_value(interface, 'user')[1].replace('"', '')
+            self.assertEqual(tmp, user)
+            tmp = get_config_value(interface, 'password')[1].replace('"', '')
+            self.assertEqual(tmp, passwd)
+            tmp = get_config_value(interface, 'ifname')[1]
+            self.assertEqual(tmp, interface)
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/src/conf_mode/interfaces-pppoe.py b/src/conf_mode/interfaces-pppoe.py
index 0a03a172c..42f084309 100755
--- a/src/conf_mode/interfaces-pppoe.py
+++ b/src/conf_mode/interfaces-pppoe.py
@@ -61,6 +61,12 @@ def get_config(config=None):
             # bail out early - no need to further process other nodes
             break
 
+    if 'deleted' not in pppoe:
+        # We always set the MRU value to the MTU size. This code path only re-creates
+        # the old behavior if MRU is not set on the CLI.
+        if 'mru' not in pppoe:
+            pppoe['mru'] = pppoe['mtu']
+
     return pppoe
 
 def verify(pppoe):