Fix missing SNMPv1 instance values (#24)

Author: SoundGoof

netsnmp/client_intf.c

@@ -1623,6 +1623,9 @@ netsnmp_get(PyObject *self, PyObject *args)
         vars && (varlist_ind < varlist_len);
         vars = vars->next_variable, varlist_ind++) {
 
+      if (err_ind >= 1 && varlist_ind >= err_ind - 1)
+        continue;
+
       varbind = PySequence_GetItem(varlist, varlist_ind);
 
       if (PyObject_HasAttrString(varbind, "tag")) {

netsnmp/tests/system/test_errors.py

@@ -30,6 +30,12 @@ def test_unknown_oid_returns_no_value(self):
         self.assertEqual(values, (None,))
         self.assertIn(varbind.type, ('NOSUCHOBJECT', 'NOSUCHINSTANCE'))
 
+    def test_unknown_instance_returns_no_value(self):
+        varbind = netsnmp.Varbind(SYS_DESCR, '123')
+
+        self.assertEqual(netsnmp.snmpget(varbind, **READ_ARGS), (None,))
+        self.assertEqual(varbind.type, 'NOSUCHINSTANCE')
+
     def test_read_only_set_is_rejected(self):
         session = netsnmp.Session(**READ_ARGS)
         varlist = netsnmp.VarList(

netsnmp/tests/system/test_v1.py

@@ -24,6 +24,13 @@ def test_get(self):
             netsnmp.Varbind(SYS_DESCR, '0'), **V1_READ_ARGS)
         assert_value(self, values)
 
+    def test_get_unknown_instance_returns_no_value(self):
+        varbind = netsnmp.Varbind(SYS_DESCR, '123')
+
+        self.assertEqual(netsnmp.snmpget(varbind, **V1_READ_ARGS), (None,))
+        self.assertIsNone(varbind.val)
+        self.assertIsNone(varbind.type)
+
     def test_getnext(self):
         values = netsnmp.snmpgetnext(
             netsnmp.Varbind(SYSTEM), **V1_READ_ARGS)