dhcp: T5787: Prevent duplicate IP addresses on static mappings

2 files changed, 13 insertions, 0 deletions

diff --git a/smoketest/scripts/cli/test_service_dhcp-server.py b/smoketest/scripts/cli/test_service_dhcp-server.py
index 093e43494..91ae901cd 100755
--- a/smoketest/scripts/cli/test_service_dhcp-server.py
+++ b/smoketest/scripts/cli/test_service_dhcp-server.py
@@ -202,6 +202,13 @@ class TestServiceDHCPServer(VyOSUnitTestSHIM.TestCase):
             self.cli_set(pool + ['static-mapping', client, 'ip-address', inc_ip(subnet, client_base)])
             client_base += 1
 
+        # cannot have mappings with duplicate IP addresses
+        with self.assertRaises(ConfigSessionError):
+            self.cli_set(pool + ['static-mapping', 'dupe1', 'mac', '00:50:00:00:00:01'])
+            self.cli_set(pool + ['static-mapping', 'dupe1', 'ip-address', inc_ip(subnet, 10)])
+            self.cli_commit()
+        self.cli_delete(pool + ['static-mapping', 'dupe1'])
+
         # commit changes
         self.cli_commit()
 
diff --git a/src/conf_mode/service_dhcp-server.py b/src/conf_mode/service_dhcp-server.py
index ac7d95632..8d849b1e6 100755
--- a/src/conf_mode/service_dhcp-server.py
+++ b/src/conf_mode/service_dhcp-server.py
@@ -214,6 +214,7 @@ def verify(dhcp):
 
             if 'static_mapping' in subnet_config:
                 # Static mappings require just a MAC address (will use an IP from the dynamic pool if IP is not set)
+                used_ips = []
                 for mapping, mapping_config in subnet_config['static_mapping'].items():
                     if 'ip_address' in mapping_config:
                         if ip_address(mapping_config['ip_address']) not in ip_network(subnet):
@@ -224,6 +225,11 @@ def verify(dhcp):
                             raise ConfigError(f'MAC address required for static mapping "{mapping}"\n' \
                                               f'within shared-network "{network}, {subnet}"!')
 
+                        if mapping_config['ip_address'] in used_ips:
+                            raise ConfigError(f'Configured IP address for static mapping "{mapping}" exists on another static mapping')
+
+                        used_ips.append(mapping_config['ip_address'])
+
             # There must be one subnet connected to a listen interface.
             # This only counts if the network itself is not disabled!
             if 'disable' not in network_config: