wsgi: server MUST NOT send Content-Length/Transfer-Encoding header in response with a status code of 1xx, 204 or (2xx to CONNECT request)746-chunked-204

https://httpwg.org/specs/rfc7230.html#rfc.section.3.3.1

https://github.com/eventlet/eventlet/issues/746

2 files changed, 26 insertions, 3 deletions

diff --git a/eventlet/wsgi.py b/eventlet/wsgi.py
index 7ef0254..8af3027 100644
--- a/eventlet/wsgi.py
+++ b/eventlet/wsgi.py
@@ -479,6 +479,9 @@ class HttpProtocol(BaseHTTPServer.BaseHTTPRequestHandler):
         use_chunked = [False]
         length = [0]
         status_code = [200]
+        # Status code of 1xx or 204 or 2xx to CONNECT request MUST NOT send body and related headers
+        # https://httpwg.org/specs/rfc7230.html#rfc.section.3.3.1
+        bodyless = [False]
 
         def write(data):
             towrite = []
@@ -510,7 +513,7 @@ class HttpProtocol(BaseHTTPServer.BaseHTTPRequestHandler):
                     self.close_connection = 1
 
                 if 'content-length' not in header_list:
-                    if self.request_version == 'HTTP/1.1':
+                    if not bodyless[0] and self.request_version == 'HTTP/1.1':
                         use_chunked[0] = True
                         towrite.append(b'Transfer-Encoding: chunked\r\n')
                     elif 'content-length' not in header_list:
@@ -534,7 +537,7 @@ class HttpProtocol(BaseHTTPServer.BaseHTTPRequestHandler):
             length[0] = length[0] + sum(map(len, towrite))
 
         def start_response(status, response_headers, exc_info=None):
-            status_code[0] = status.split()[0]
+            status_code[0] = int(status.split(" ", 1)[0])
             if exc_info:
                 try:
                     if headers_sent:
@@ -544,6 +547,12 @@ class HttpProtocol(BaseHTTPServer.BaseHTTPRequestHandler):
                     # Avoid dangling circular ref
                     exc_info = None
 
+            bodyless[0] = (
+                status_code[0] == 204
+                or (100 <= status_code[0] < 200)
+                or (self.command == "CONNECT" and 200 <= status_code[0] < 300)
+            )
+
             # Response headers capitalization
             # CONTent-TYpe: TExt/PlaiN -> Content-Type: TExt/PlaiN
             # Per HTTP RFC standard, header name is case-insensitive.
@@ -571,7 +580,7 @@ class HttpProtocol(BaseHTTPServer.BaseHTTPRequestHandler):
                 # Set content-length if possible
                 if headers_set and not headers_sent and hasattr(result, '__len__'):
                     # We've got a complete final response
-                    if 'Content-Length' not in [h for h, _v in headers_set[1]]:
+                    if not bodyless[0] and 'Content-Length' not in [h for h, _v in headers_set[1]]:
                         headers_set[1].append(('Content-Length', str(sum(map(len, result)))))
                     if request_input.should_send_hundred_continue:
                         # We've got a complete final response, and never sent a 100 Continue.
diff --git a/tests/wsgi_test.py b/tests/wsgi_test.py
index 999d6f0..6f1a613 100644
--- a/tests/wsgi_test.py
+++ b/tests/wsgi_test.py
@@ -1862,6 +1862,20 @@ class TestHttpd(_TestBase):
         except Exception:
             assert False, self.logfile.getvalue()
 
+    def test_no_transfer_encoding_in_empty_response(self):
+        def app(environ, start_response):
+            write = start_response("204 OK", [])
+            write(b"")
+
+        self.spawn_server(site=app)
+        sock = eventlet.connect(self.server_addr)
+        sock.sendall(b"DELETE /foo HTTP/1.1\r\n\r\n")
+
+        response = read_http(sock)
+        sock.close()
+        print(response)
+        assert "transfer-encoding" not in response.headers_lower
+
 
 def read_headers(sock):
     fd = sock.makefile('rb')