ContentLengthMiddleware: don't duplicate the header

When an iterable is returned and a Content-Length header is already
present, don't add a second one.

1 files changed, 12 insertions, 11 deletions

diff --git a/wsgitools/middlewares.py b/wsgitools/middlewares.py
index 97b8092..1619e0b 100644
--- a/wsgitools/middlewares.py
+++ b/wsgitools/middlewares.py
@@ -166,7 +166,7 @@ class ContentLengthMiddleware(object):
             gotdata = True
             assert bool(todo)
             status, headers = todo[0]
-            if not [k for k, _ in headers if k.lower() == "content-length"]:
+            if all(k.lower() != "content-length" for k, _ in headers):
                 length = sum(map(len, ret))
                 headers.append(("Content-Length", str(length)))
             start_response(status, headers)
@@ -188,17 +188,18 @@ class ContentLengthMiddleware(object):
             data.append(first)
         length = len(first)
 
-        while (not stopped) and length < self.maxstore:
-            try:
-                data.append(next(ret))
-                length += len(data[-1])
-            except StopIteration:
-                stopped = True
+        if all(k.lower() != "content-length" for k, _ in headers):
+            while (not stopped) and length < self.maxstore:
+                try:
+                    data.append(next(ret))
+                    length += len(data[-1])
+                except StopIteration:
+                    stopped = True
 
-        if stopped:
-            headers.append(("Content-length", str(length)))
-            start_response(status, headers)
-            return data
+            if stopped:
+                headers.append(("Content-length", str(length)))
+                start_response(status, headers)
+                return data
 
         start_response(status, headers)