rapid-cdn: c->h: setup Date header

In case if Date header is present do nothing otherwise add one.
Test backend is adapted to have full control over headers sent.

Backward incompatible change happens, as the Date header is generated
before passing the request to the cache, thus resulting with caching it.
Nevertheless this is good change, as previous behavior was simply wrong.

software/rapid-cdn/buildout.hash.cfg

@@ -50,7 +50,7 @@ md5sum = 88af61e7abbf30dc99a1a2526161128d
 
 [template-backend-haproxy-configuration]
 _update_hash_filename_ = templates/backend-haproxy.cfg.in
-md5sum = 5dd9e33a3c69afd60eae8234589512dc
+md5sum = 6a1c91b74266b4d819051b29458d613f
 
 [template-empty]
 _update_hash_filename_ = templates/empty.in

software/rapid-cdn/templates/backend-haproxy.cfg.in

@@ -60,6 +60,8 @@ frontend http-backend
   bind {{ configuration['local-ipv4'] }}:{{ configuration['http-port'] }}
   http-request add-header Via "%HV rapid-cdn-backend-{{ configuration['node-id'] }}-{{ configuration['version-hash'] }}"
   http-response add-header Via "%HV rapid-cdn-backend-{{ configuration['node-id'] }}-{{ configuration['version-hash']}}"
+  # setup Date
+  http-response set-header Date %[date(),http_date] if ! { res.hdr(Date) -m found }
 {%- for slave_instance in backend_slave_list -%}
 {{ frontend_entry(slave_instance, 'http', False) }}
 {%- endfor %}
@@ -71,6 +73,8 @@ frontend https-backend
   bind {{ configuration['local-ipv4'] }}:{{ configuration['https-port'] }}
   http-request add-header Via "%HV rapid-cdn-backend-{{ configuration['node-id'] }}-{{ configuration['version-hash'] }}"
   http-response add-header Via "%HV rapid-cdn-backend-{{ configuration['node-id'] }}-{{ configuration['version-hash']}}"
+  # setup Date
+  http-response set-header Date %[date(),http_date] if ! { res.hdr(Date) -m found }
 {%- for slave_instance in backend_slave_list -%}
 {{ frontend_entry(slave_instance, 'https', False) }}
 {%- endfor %}

software/rapid-cdn/test/test.py

@@ -703,7 +703,8 @@ class TestHandler(BaseHTTPRequestHandler):
         response = base64.b64decode(self.headers['x-reply-body'])
 
     time.sleep(timeout)
-    self.send_response(status_code)
+    self.send_response_only(status_code)
+    self.send_header('Server', self.server_version)
 
     for key, value in list(header_dict.items()):
       self.send_header(key, value)
@@ -4506,6 +4507,30 @@ class TestSlave(SlaveHttpFrontendTestCase, TestDataMixin, AtsMixin):
   timeout connect 10s
   retries 5""" in content)
 
+  def test_header_date(self):
+    # Precisely check out Date header behaviour
+    frontend = 'url_https-url'
+    parameter_dict = self.assertSlaveBase(frontend)
+    backend_url = self.getSlaveParameterDictDict()[
+      frontend]['https-url'].strip()
+    normal_path = 'normal'
+    with_date_path = 'with_date'
+    specific_date = 'Fri, 07 Dec 2001 00:00:00 GMT'
+    result_configure = requests.put(
+      backend_url + '/' + with_date_path, headers={
+        'X-Reply-Header-Date': specific_date
+      })
+    self.assertEqual(result_configure.status_code, http.client.CREATED)
+
+    result_normal = fakeHTTPSResult(parameter_dict['domain'], normal_path)
+    result_with_date = fakeHTTPSResult(
+      parameter_dict['domain'], with_date_path)
+
+    # Prove that Date header with value specific_date send by backend is NOT
+    # modified by the CDN, but some Date header is added, if backend sends non
+    self.assertEqual(result_with_date.headers['Date'], specific_date)
+    self.assertNotEqual(result_normal.headers['Date'], specific_date)
+
   def test_https_url_netloc_list(self):
     parameter_dict = self.assertSlaveBase('https-url-netloc-list')
     result = fakeHTTPSResult(parameter_dict['domain'], 'path')