policy: T4194: simplify prefix-list duplication checks

Commit 5dafe255d ("policy: T4194: Add prefix-list duplication checks") added
first support for FRR prefix-list duplication checks. FRR does not allow to
specify the same profix list rule multiple times.

  vyos(config)# ip prefix-list foo seq 10 permit 192.0.2.0/24
  vyos(config)# ip prefix-list foo seq 20 permit 192.0.2.0/24
  % Configuration failed.
  Error type: validation
  Error description: duplicated prefix list value: 192.0.2.0/24

There is a VyOS verify() function which simply probed for the prefix, action,
le and ge settings - but as Python has excellent support when comparing data,
this can be as simple as a dictionary comparison using "==".

2 files changed, 38 insertions, 5 deletions

diff --git a/smoketest/scripts/cli/test_policy.py b/smoketest/scripts/cli/test_policy.py
index 0acd41903..b232a2241 100755
--- a/smoketest/scripts/cli/test_policy.py
+++ b/smoketest/scripts/cli/test_policy.py
@@ -665,6 +665,40 @@ class TestPolicy(VyOSUnitTestSHIM.TestCase):
 
                 self.assertIn(tmp, config)
 
+    def test_prefix_list_duplicates(self):
+        # FRR does not allow to specify the same profix list rule multiple times
+        #
+        # vyos(config)# ip prefix-list foo seq 10 permit 192.0.2.0/24
+        # vyos(config)# ip prefix-list foo seq 20 permit 192.0.2.0/24
+        # % Configuration failed.
+        # Error type: validation
+        # Error description: duplicated prefix list value: 192.0.2.0/24
+
+        # There is also a VyOS verify() function to test this
+
+        prefix = '100.64.0.0/10'
+        prefix_list = 'duplicates'
+        test_range = range(20, 25)
+        path = base_path + ['prefix-list', prefix_list]
+
+        for rule in test_range:
+            self.cli_set(path + ['rule', str(rule), 'action', 'permit'])
+            self.cli_set(path + ['rule', str(rule), 'prefix', prefix])
+
+        # Duplicate prefixes
+        with self.assertRaises(ConfigSessionError):
+            self.cli_commit()
+
+        for rule in test_range:
+            self.cli_set(path + ['rule', str(rule), 'le', str(rule)])
+
+        self.cli_commit()
+
+        config = self.getFRRconfig('ip prefix-list', end='')
+        for rule in test_range:
+            tmp = f'ip prefix-list {prefix_list} seq {rule} permit {prefix} le {rule}'
+            self.assertIn(tmp, config)
+
     def test_route_map(self):
         access_list = '50'
         as_path_list = '100'
diff --git a/src/conf_mode/policy.py b/src/conf_mode/policy.py
index 6b1d3bf1a..9d8fcfa36 100755
--- a/src/conf_mode/policy.py
+++ b/src/conf_mode/policy.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2021 VyOS maintainers and contributors
+# Copyright (C) 2021-2022 VyOS maintainers and contributors
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 or later as
@@ -114,10 +114,9 @@ def verify(policy):
                     if 'prefix' not in rule_config:
                         raise ConfigError(f'A prefix {mandatory_error}')
 
-                    # Check prefix duplicates
-                    if rule_config['prefix'] in entries and ('ge' not in rule_config and 'le' not in rule_config):
-                        raise ConfigError(f'Prefix {rule_config["prefix"]} is duplicated!')
-                    entries.append(rule_config['prefix'])
+                    if rule_config in entries:
+                        raise ConfigError(f'Rule "{rule}" contains a duplicate prefix definition!')
+                    entries.append(rule_config)
 
 
     # route-maps tend to be a bit more complex so they get their own verify() section