AssertionError: Value of header "Content-Length" must be a string

[Andre Loker]

I have tracd connected to IIS via AJP and I'm using basic authentication. When upgrading from 0.11.4 to 0.11.5rc2 whenever I try to login I get the following error:

Traceback (most recent call last):

  File "C:\Tools\Python26\lib\site-packages\flup-1.0.3.dev_20090612-py2.6.egg\flup\server\ajp_base.py", line 486, in run
    self._conn.server.handler(self)
  File "C:\Tools\Python26\lib\site-packages\flup-1.0.3.dev_20090612-py2.6.egg\flup\server\ajp_base.py", line 898, in handler
    result = self.application(environ, start_response)
  File "C:\Tools\Python26\lib\site-packages\trac-0.11.5rc2-py2.6.egg\trac\web\standalone.py", line 81, in __call__
    return self.application(environ, start_response)
  File "C:\Tools\Python26\lib\site-packages\trac-0.11.5rc2-py2.6.egg\trac\web\standalone.py", line 54, in __call__
    remote_user = auth.do_auth(environ, start_response)
  File "C:\Tools\Python26\lib\site-packages\trac-0.11.5rc2-py2.6.egg\trac\web\auth.py", line 299, in do_auth
    ('Content-Length', 0)])('')
  File "C:\Tools\Python26\lib\site-packages\flup-1.0.3.dev_20090612-py2.6.egg\flup\server\ajp_base.py", line 889, in start_response
    assert type(val) is str, 'Value of header "%s" must be a string' % name
AssertionError: Value of header "Content-Length" must be a string

As a result, no-one is able to login anymore.

I was able to fix the error by changing line 299 and 355 of trac/web/auth.py (from tags/trac-0.11.5rc2) in a way that the provided content-length is a string instead of an integer:

        start_response('401 Unauthorized',
                       [('WWW-Authenticate', 'Basic realm="%s"' % self.realm),
                        ('Content-Length', '0')])('')

and

        start_response('401 Unauthorized',
                       [('WWW-Authenticate',
                        'Digest realm="%s", nonce="%s", qop="auth", stale="%s"'
                        % (self.realm, nonce, stale)),
                        ('Content-Length', '0')])('')

Hope that helps to fix the problem.

[Andre Loker]

Probably the error occurs at more places, e.g. in web/main.py when a 404 is returned.

[Remy Blank]

I'll have a look. Thanks for the report.

[Remy Blank]

Indeed, the full patch is the following:

trac/web/auth.py

@@ -296 +296 @@
 
         start_response('401 Unauthorized',
                        [('WWW-Authenticate', 'Basic realm="%s"' % self.realm),
-                        ('Content-Length', 0)])('')
+                        ('Content-Length', '0')])('')
 
 
 class DigestAuthentication(PasswordFileAuthentication):
@@ -352 +352 @@
                        [('WWW-Authenticate',
                         'Digest realm="%s", nonce="%s", qop="auth", stale="%s"'
                         % (self.realm, nonce, stale)),
-                        ('Content-Length', 0)])('')
+                        ('Content-Length', '0')])('')
 
     def do_auth(self, environ, start_response):
         header = environ.get('HTTP_AUTHORIZATION')

trac/web/main.py

@@ -377 +377 @@
                 errmsg = 'Environment not found'
                 start_response('404 Not Found',
                                [('Content-Type', 'text/plain'),
-                                ('Content-Length', len(errmsg))])
+                                ('Content-Length', str(len(errmsg)))])
                 return [errmsg]
 
     if not env_path:

All other instances where we set the Content-Length header use req.send_header(), which converts the value to a string.

[Remy Blank]

Patch applied in [8358], thanks!