Unsolicited use of persistent connections causes HTTP/1.0 clients to hang

Forwared from http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=710672

Dear Maintainer,

pywebdav uses persistent connections even for HTTP/1.0 GET requests
without a Connection: Keep-Alive header. This causes the client to
hang waiting for the connection to close. RFC2616 explicitly states
HTTP/1.1 servers must not assume HTTP/1.0 clients to support
persistent connections:

=== Begin RFC2616 excerpt ===
8.1.2.1 Negotiation
[...]
   Clients and servers SHOULD NOT assume that a persistent connection is
   maintained for HTTP versions less than 1.1 unless it is explicitly
   signaled. [...]
=== End RFC2616 excerpt ===

In addition, both a Connection: close and a Connection: Keep-Alive
header are sent and Date is sent twice:

=== Begin tcpflow dump ===
127.000.000.001.50660-127.000.000.001.08009: GET / HTTP/1.0
User-Agent: w3m/0.5.3+cvs-1.1055
Accept: text/html, text/*;q=0.5, image/*, */*
Accept-Encoding: Xgzip, compress, bzip, bzip2, deflate
Accept-Language: en;q=1.0
Host: localhost:8009
Pragma: no-cache
Cache-control: no-cache

127.000.000.001.08009-127.000.000.001.50660: HTTP/1.0 200 OK

127.000.000.001.08009-127.000.000.001.50660: Server: DAV/0.9.8 Python/2.7.3

127.000.000.001.08009-127.000.000.001.50660: Date: Sat, 01 Jun 2013 10:11:00 GMT

127.000.000.001.08009-127.000.000.001.50660: Connection: close

127.000.000.001.08009-127.000.000.001.50660: Accept-Ranges: bytes

127.000.000.001.08009-127.000.000.001.50660: Date: Sat, 01 Jun 2013 10:11:00 GMT

127.000.000.001.08009-127.000.000.001.50660: DAV: 1

127.000.000.001.08009-127.000.000.001.50660: Last-Modified: Sat, 01 Jun 2013 
10:11:00 GMT

127.000.000.001.08009-127.000.000.001.50660: Connection: Keep-Alive

127.000.000.001.08009-127.000.000.001.50660: Keep-Alive: timeout=15, max=86

127.000.000.001.08009-127.000.000.001.50660: Content-Length: 253

127.000.000.001.08009-127.000.000.001.50660: Content-Type: text/html; 
charset=utf-8

127.000.000.001.08009-127.000.000.001.50660: 

127.000.000.001.08009-127.000.000.001.50660: <html>
<head><title>Journal listing</title></head>
<body>
<table>
<tr><th>Name</th></tr>
<tr><td><a href="by-id/">by-id/</a></td></tr>
<tr><td><a href="by-tags/">by-tags/</a></td></tr>
<tr><td><a href="by-title/">by-title/</a></td></tr>
</table>
</html>
=== End tcpflow dump ===

A quick patch for these issues:

=== Begin ===
--- WebDAVServer.py.old 2013-06-01 14:23:19.105319133 +0200
+++ WebDAVServer.py     2013-06-01 14:23:35.457092427 +0200
@@ -62,9 +62,9 @@
         log.debug("Use send_body method")

         self.send_response(code, message=msg)
-        self.send_header("Connection", "close")
+        if 'Connection' not in headers:
+            self.send_header("Connection", "close")
         self.send_header("Accept-Ranges", "bytes")
-        self.send_header('Date', rfc1123_date())

         self._send_dav_version()

@@ -255,8 +255,9 @@
             self.send_body(data, status_code, None, None, content_type,
                            headers)
         else:
-            headers['Keep-Alive'] = 'timeout=15, max=86'
-            headers['Connection'] = 'Keep-Alive'
+            if self.request_version == 'HTTP/1.1':
+                headers['Keep-Alive'] = 'timeout=15, max=86'
+                headers['Connection'] = 'Keep-Alive'
             self.send_body_chunks_if_http11(data, status_code, None, None,
                                             content_type, headers)
=== End ===
Original issue reported on code.google.com by mathi...@m9s.biz on 1 Jun 2013 at 5:15
biggosh / pywebdav

Unsolicited use of persistent connections causes HTTP/1.0 clients to hang #69
