snmp: T3996: fix invalid IPv6 localhost handling when using listen-address

We need to use a temporary variable when validating the tuple if address
is used. If not the else branch will always add the tuple to the list of
addresses used for listen-address.

2 files changed, 36 insertions, 16 deletions

diff --git a/smoketest/scripts/cli/test_service_snmp.py b/smoketest/scripts/cli/test_service_snmp.py
index 008271102..e15d186bc 100755
--- a/smoketest/scripts/cli/test_service_snmp.py
+++ b/smoketest/scripts/cli/test_service_snmp.py
@@ -22,6 +22,7 @@ from base_vyostest_shim import VyOSUnitTestSHIM
 from vyos.configsession import ConfigSession
 from vyos.configsession import ConfigSessionError
 from vyos.template import is_ipv4
+from vyos.template import address_from_cidr
 from vyos.util import read_file
 from vyos.util import process_named_running
 
@@ -36,16 +37,29 @@ def get_config_value(key):
     return tmp[0]
 
 class TestSNMPService(VyOSUnitTestSHIM.TestCase):
-    def setUp(self):
+    @classmethod
+    def setUpClass(cls):
+        super(cls, 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)
+
+    def tearDown(self):
+        # delete testing SNMP config
         self.cli_delete(base_path)
+        self.cli_commit()
 
     def test_snmp_basic(self):
+        dummy_if = 'dum7312'
+        dummy_addr = '100.64.0.1/32'
+        self.cli_set(['interfaces', 'dummy', dummy_if, 'address', dummy_addr])
+
         # Check if SNMP can be configured and service runs
         clients = ['192.0.2.1', '2001:db8::1']
         networks = ['192.0.2.128/25', '2001:db8:babe::/48']
-        listen = ['127.0.0.1', '::1']
+        listen = ['127.0.0.1', '::1', address_from_cidr(dummy_addr)]
+        port = '5000'
 
         for auth in ['ro', 'rw']:
             community = 'VyOS' + auth
@@ -56,7 +70,7 @@ class TestSNMPService(VyOSUnitTestSHIM.TestCase):
                 self.cli_set(base_path + ['community', community, 'network', network])
 
         for addr in listen:
-            self.cli_set(base_path + ['listen-address', addr])
+            self.cli_set(base_path + ['listen-address', addr, 'port', port])
 
         self.cli_set(base_path + ['contact', 'maintainers@vyos.io'])
         self.cli_set(base_path + ['location', 'qemu'])
@@ -68,16 +82,18 @@ class TestSNMPService(VyOSUnitTestSHIM.TestCase):
         # thus we need to transfor this into a proper list
         config = get_config_value('agentaddress')
         expected = 'unix:/run/snmpd.socket'
+        self.assertIn(expected, config)
+
         for addr in listen:
             if is_ipv4(addr):
-                expected += ',udp:{}:161'.format(addr)
+                expected = f'udp:{addr}:{port}'
             else:
-                expected += ',udp6:[{}]:161'.format(addr)
-
-        self.assertTrue(expected in config)
+                expected = f'udp6:[{addr}]:{port}'
+            self.assertIn(expected, config)
 
         # Check for running process
         self.assertTrue(process_named_running(PROCESS_NAME))
+        self.cli_delete(['interfaces', 'dummy', dummy_if])
 
 
     def test_snmpv3_sha(self):
@@ -86,7 +102,7 @@ class TestSNMPService(VyOSUnitTestSHIM.TestCase):
 
         self.cli_set(base_path + ['v3', 'engineid', '000000000000000000000002'])
         self.cli_set(base_path + ['v3', 'group', 'default', 'mode', 'ro'])
-        # check validate() - a view must be created before this can be comitted
+        # check validate() - a view must be created before this can be committed
         with self.assertRaises(ConfigSessionError):
             self.cli_commit()
 
@@ -152,4 +168,3 @@ class TestSNMPService(VyOSUnitTestSHIM.TestCase):
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)
-
diff --git a/src/conf_mode/snmp.py b/src/conf_mode/snmp.py
index 2a420b193..e1852f2ce 100755
--- a/src/conf_mode/snmp.py
+++ b/src/conf_mode/snmp.py
@@ -20,13 +20,17 @@ from sys import exit
 
 from vyos.config import Config
 from vyos.configverify import verify_vrf
-from vyos.snmpv3_hashgen import plaintext_to_md5, plaintext_to_sha1, random
+from vyos.snmpv3_hashgen import plaintext_to_md5
+from vyos.snmpv3_hashgen import plaintext_to_sha1
+from vyos.snmpv3_hashgen import random
 from vyos.template import render
 from vyos.template import is_ipv4
-from vyos.util import call, chmod_755
+from vyos.util import call
+from vyos.util import chmod_755
 from vyos.validate import is_addr_assigned
 from vyos.version import get_version_data
-from vyos import ConfigError, airbag
+from vyos import ConfigError
+from vyos import airbag
 airbag.enable()
 
 config_file_client  = r'/etc/snmp/snmp.conf'
@@ -410,19 +414,20 @@ def verify(snmp):
         port = listen[1]
         protocol = snmp['protocol']
 
+        tmp = None
         if is_ipv4(addr):
             # example: udp:127.0.0.1:161
-            listen = f'{protocol}:{addr}:{port}'
+            tmp = f'{protocol}:{addr}:{port}'
         elif snmp['ipv6_enabled']:
             # example: udp6:[::1]:161
-            listen = f'{protocol}6:[{addr}]:{port}'
+            tmp = f'{protocol}6:[{addr}]:{port}'
 
         # We only wan't to configure addresses that exist on the system.
         # Hint the user if they don't exist
         if is_addr_assigned(addr):
-            snmp['listen_on'].append(listen)
+            if tmp: snmp['listen_on'].append(tmp)
         else:
-            print('WARNING: SNMP listen address {0} not configured!'.format(addr))
+            print(f'WARNING: SNMP listen address {addr} not configured!')
 
     verify_vrf(snmp)