contrib/win32/hgwebdir_wsgi.py

wireproto: support disabling bundle1 only if repo is generaldelta

I recently implemented the server.bundle1* options to control whether
bundle1 exchange is allowed.

After thinking about Mozilla's strategy for handling generaldelta
rollout a bit more, I think server operators need an additional
lever: disable bundle1 if and only if the repo is generaldelta.

bundle1 exchange for non-generaldelta repos will not have the potential
for CPU explosion that generaldelta repos do. Therefore, it makes sense
for server operators to continue to allow bundle1 exchange for
non-generaldelta repos without having to set a per-repo hgrc option
to change the policy depending on whether the repo is generaldelta.

This patch introduces a new set of options to control bundle1 behavior
for generaldelta repos. These options enable server operators to limit
bundle1 restrictions to the class of repos that can be performance
issues. It also allows server operators to tie bundle1 access to store
format. In many server environments (including Mozilla's), legacy repos
will not be generaldelta and new repos will or might be. New repos often
aren't bound by legacy access requirements, so setting a global policy
that disallows access to new/generaldelta repos via bundle1 could be a
reasonable policy in many server environments. This patch makes this
policy very easy to implement (modify global hgrc, add options to
existing generaldelta repos to grandfather them in).

# An example WSGI script for IIS/isapi-wsgi to export multiple hgweb repos
# Copyright 2010 Sune Foldager <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
#
# Requirements:
# - Python 2.6
# - PyWin32 build 214 or newer
# - Mercurial installed from source (python setup.py install)
# - IIS 7
#
# Earlier versions will in general work as well, but the PyWin32 version is
# necessary for win32traceutil to work correctly.
#
#
# Installation and use:
#
# - Download the isapi-wsgi source and run python setup.py install:
#   http://code.google.com/p/isapi-wsgi/
#
# - Run this script (i.e. python hgwebdir_wsgi.py) to get a shim dll. The
#   shim is identical for all scripts, so you can just copy and rename one
#   from an earlier run, if you wish.
#
# - Setup an IIS application where your hgwebdir is to be served from.
#   On 64-bit systems, make sure it's assigned a 32-bit app pool.
#
# - In the application, setup a wildcard script handler mapping of type
#   IsapiModule with the shim dll as its executable. This file MUST reside
#   in the same directory as the shim. Remove all other handlers, if you wish.
#
# - Make sure the ISAPI and CGI restrictions (configured globally on the
#   web server) includes the shim dll, to allow it to run.
#
# - Adjust the configuration variables below to match your needs.
#

# Configuration file location
hgweb_config = r'c:\src\iis\hg\hgweb.config'

# Global settings for IIS path translation
path_strip = 0   # Strip this many path elements off (when using url rewrite)
path_prefix = 1  # This many path elements are prefixes (depends on the
                 # virtual path of the IIS application).

import sys

# Adjust python path if this is not a system-wide install
#sys.path.insert(0, r'c:\path\to\python\lib')

# Enable tracing. Run 'python -m win32traceutil' to debug
if getattr(sys, 'isapidllhandle', None) is not None:
    import win32traceutil
    win32traceutil.SetupForPrint # silence unused import warning

# To serve pages in local charset instead of UTF-8, remove the two lines below
import os
os.environ['HGENCODING'] = 'UTF-8'


import isapi_wsgi
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb.hgwebdir_mod import hgwebdir

# Example tweak: Replace isapi_wsgi's handler to provide better error message
# Other stuff could also be done here, like logging errors etc.
class WsgiHandler(isapi_wsgi.IsapiWsgiHandler):
    error_status = '500 Internal Server Error' # less silly error message

isapi_wsgi.IsapiWsgiHandler = WsgiHandler

# Only create the hgwebdir instance once
application = hgwebdir(hgweb_config)

def handler(environ, start_response):

    # Translate IIS's weird URLs
    url = environ['SCRIPT_NAME'] + environ['PATH_INFO']
    paths = url[1:].split('/')[path_strip:]
    script_name = '/' + '/'.join(paths[:path_prefix])
    path_info = '/'.join(paths[path_prefix:])
    if path_info:
        path_info = '/' + path_info
    environ['SCRIPT_NAME'] = script_name
    environ['PATH_INFO'] = path_info

    return application(environ, start_response)

def __ExtensionFactory__():
    return isapi_wsgi.ISAPISimpleHandler(handler)

if __name__=='__main__':
    from isapi.install import ISAPIParameters, HandleCommandLine
    params = ISAPIParameters()
    HandleCommandLine(params)