Validate node id for log handler

This change updates the log handler to validate that the node id being
passed in is an integer. If it is not an integer, the response will be a
400.

Change-Id: Ida7a18a7261bf7fa98518a059d1de42690382d79
Closes-Bug: #1585160
(cherry picked from commit 9791794754)

nailgun/nailgun/api/v1/handlers/logs.py

@@ -311,7 +311,12 @@ class LogEntryCollectionHandler(BaseHandler):
         if log_config['remote'] and not log_config.get('fake'):
             if not user_data.get('node'):
                 raise self.http(400, "'node' must be specified")
-            node = objects.Node.get_by_uid(user_data.get('node'))
+            try:
+                node_id = int(user_data.get('node'))
+            except ValueError:
+                logger.debug("Invalid 'node' value: %r", user_data.get('node'))
+                raise self.http(400, "Invalid 'node' value")
+            node = objects.Node.get_by_uid(node_id)
             if not node:
                 raise self.http(404, "Node not found")
             if not node.ip:

nailgun/nailgun/test/unit/test_logs_handlers.py

@@ -554,3 +554,12 @@ class TestLogs(BaseIntegrationTest):
 
         params = mcast.call_args_list[0][0]
         self.assertEqual(params[1]['args']['settings'], custom_config)
+
+    def test_logs_handler_with_invalid_id(self):
+        resp = self.app.get(
+            reverse('LogEntryCollectionHandler'),
+            params={'id': 'abcd'},
+            headers=self.default_headers,
+            expect_errors=True
+        )
+        self.assertEqual(400, resp.status_code)