origin header improvement: if Referer header is available, compute Origin from the Referer, not from target url (#329)

(Origin header received will be the pywb host, using Referer will result in more accurate Origin, which may not be the target url)
tests: add tests to verify Origin header with and without Referer

pywb/rewrite/rewriteinputreq.py

@@ -49,8 +49,14 @@ class RewriteInputRequest(DirectWSGIInputRequest):
 
             elif name == 'HTTP_ORIGIN':
                 name = 'Origin'
-                if self.splits:
-                    value = (self.splits.scheme + '://' + self.splits.netloc)
+                referrer = self.env.get('HTTP_REFERER')
+                if referrer:
+                    splits = urlsplit(referrer)
+                else:
+                    splits = self.splits
+
+                if splits:
+                    value = (splits.scheme + '://' + splits.netloc)
 
             elif name == 'HTTP_X_CSRFTOKEN':
                 name = 'X-CSRFToken'

tests/test_live_rewriter.py

@@ -64,3 +64,22 @@ class TestLiveRewriter(HttpBinLiveTests, BaseConfigTest):
     def test_deflate(self, fmod_sl):
         resp = self.get('/live/{0}http://httpbin.org/deflate', fmod_sl)
         assert b'"deflated": true' in resp.body
+
+    def test_live_origin_and_referrer(self, fmod_sl):
+        headers = {'Referer': 'http://localhost:80/live/{0}http://example.com/test'.format(fmod_sl),
+                   'Origin': 'http://localhost:80'
+                  }
+
+        resp = self.get('/live/{0}http://httpbin.org/get?test=headers', fmod_sl, headers=headers)
+
+        assert resp.json['headers']['Referer'] == 'http://example.com/test'
+        assert resp.json['headers']['Origin'] == 'http://example.com'
+
+    def test_live_origin_no_referrer(self, fmod_sl):
+        headers = {'Origin': 'http://localhost:80'}
+
+        resp = self.get('/live/{0}http://httpbin.org/get?test=headers', fmod_sl, headers=headers)
+
+        assert resp.json['headers']['Origin'] == 'http://httpbin.org'
+
+