Add an interface to override to output payload of the client. Fix #37

Author: pylessard

test/client/test_client.py

@@ -107,3 +107,29 @@ def _test_p2_star_timeout(self):
             self.assertGreater(diff, timeout, 'Timeout raised after %.3f seconds when it should be %.3f sec' % (diff, timeout))
             self.assertLess(diff, timeout+0.5, 'Timeout raised after %.3f seconds when it should be %.3f sec' % (diff, timeout))
 
+
+    def test_payload_override_literal(self):
+        request = self.conn.touserqueue.get(timeout=0.2)
+        self.assertEqual(request, b'\x12\x34\x56\x78')
+        self.conn.fromuserqueue.put(b"\x7E\x00")
+
+    def _test_payload_override_literal(self):
+        req = Request(service = services.TesterPresent, subfunction=0) 
+        with self.udsclient.payload_override(b'\x12\x34\x56\x78'):
+            response = self.udsclient.send_request(req)
+            self.assertEqual(response.original_payload, b'\x7E\x00')
+
+
+    def test_payload_override_func(self):
+        request = self.conn.touserqueue.get(timeout=0.2)
+        self.assertEqual(request, b'\x99\x88\x77\x66')
+        self.conn.fromuserqueue.put(b"\x7E\x00")
+
+    def _test_payload_override_func(self):
+        def func(payload):
+            return b'\x99\x88\x77\x66'
+
+        req = Request(service = services.TesterPresent, subfunction=0) 
+        with self.udsclient.payload_override(func):
+            response = self.udsclient.send_request(req)
+            self.assertEqual(response.original_payload, b'\x7E\x00')

udsoncan/client.py

@@ -37,6 +37,30 @@ def __enter__(self):
         def __exit__(self, type, value, traceback):
             self.enabled = False
 
+    class PayloadOverrider:
+        def __init__(self):
+            self.modifier = None
+            self.enabled = False
+
+        def __enter__(self):
+            self.enabled = True
+            return self
+
+        def __exit__(self, type, value, traceback):
+            self.modifier = None
+            self.enabled = False
+
+        def __call__(self, modifier):
+            self.modifier = modifier
+            return self
+
+        def get_overrided_payload(self, original_payload):
+            if callable(self.modifier):
+                return self.modifier(original_payload)
+            else:
+                return self.modifier
+
+
     def __init__(self, conn, config=default_client_config, request_timeout=None):
         self.conn = conn
         self.config = dict(config) # Makes a copy of given configuration
@@ -45,6 +69,7 @@ def __init__(self, conn, config=default_client_config, request_timeout=None):
         if request_timeout is not None:
             self.config['request_timeout'] = request_timeout
         self.suppress_positive_response = Client.SuppressPositiveResponse()
+        self.payload_override = Client.PayloadOverrider()
         self.last_response = None
 
         self.refresh_config()
@@ -1435,6 +1460,9 @@ def send_request(self, request, timeout=-1):
         else:
             payload = request.get_payload()
 
+        if self.payload_override.enabled:
+            payload = self.payload_override.get_overrided_payload(payload)
+
         if self.suppress_positive_response.enabled and not request.service.use_subfunction():
             self.logger.warning('SuppressPositiveResponse cannot be used for service %s. Ignoring' % (request.service.get_name()))