Import //fetch from Web Platform Tests.

third_party/WebKit/LayoutTests/external/wpt/fetch/api/resources/redirect.py

+from urllib import urlencode
+from urlparse import urlparse
+
+def main(request, response):
+    stashed_data = {'count': 0, 'preflight': "0"}
+    status = 302
+    headers = [("Content-Type", "text/plain"),
+               ("Cache-Control", "no-cache"),
+               ("Pragma", "no-cache"),
+               ("Access-Control-Allow-Origin", "*")]
+    token = None
+
+    if "token" in request.GET:
+        token = request.GET.first("token")
+        data = request.server.stash.take(token)
+        if data:
+            stashed_data = data
+
+    if request.method == "OPTIONS":
+        if "allow_headers" in request.GET:
+            headers.append(("Access-Control-Allow-Headers", request.GET['allow_headers']))
+        stashed_data['preflight'] = "1"
+        #Preflight is not redirected: return 200
+        if not "redirect_preflight" in request.GET:
+            if token:
+              request.server.stash.put(request.GET.first("token"), stashed_data)
+            return 200, headers, ""
+
+    if "redirect_status" in request.GET:
+        status = int(request.GET['redirect_status'])
+
+    stashed_data['count'] += 1
+
+    if "location" in request.GET:
+        url = request.GET['location']
+        scheme = urlparse(url).scheme
+        if scheme == "" or scheme == "http" or scheme == "https":
+            url += "&" if '?' in url else "?"
+            #keep url parameters in location
+            url_parameters = {}
+            for item in request.GET.items():
+                url_parameters[item[0]] = item[1][0]
+            url += urlencode(url_parameters)
+            #make sure location changes during redirection loop
+            url += "&count=" + str(stashed_data['count'])
+        headers.append(("Location", url))
+
+    if "redirect_referrerpolicy" in request.GET:
+        headers.append(("Referrer-Policy", request.GET['redirect_referrerpolicy']))
+
+    if token:
+        request.server.stash.put(request.GET.first("token"), stashed_data)
+        if "max_count" in request.GET:
+            max_count =  int(request.GET['max_count'])
+            #stop redirecting and return count
+            if stashed_data['count'] > max_count:
+                # -1 because the last is not a redirection
+                return str(stashed_data['count'] - 1)
+
+    return status, headers, ""