http2: mark experimental and developer options

mercurial/httpconnection.py

@@ -1,283 +1,284 b''
 # httpconnection.py - urllib2 handler for new http support
 #
 # Copyright 2005, 2006, 2007, 2008 Matt Mackall <[e-mail]>
 # Copyright 2006, 2007 Alexis S. L. Carvalho <[e-mail]>
 # Copyright 2006 Vadim Gelfer <[e-mail]>
 # Copyright 2011 Google, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 import logging
 import socket
 import urllib
 import urllib2
 import os
 
 from mercurial import httpclient
 from mercurial import sslutil
 from mercurial import util
 from mercurial.i18n import _
 
 # moved here from url.py to avoid a cycle
 class httpsendfile(object):
     """This is a wrapper around the objects returned by python's "open".
 
     Its purpose is to send file-like objects via HTTP.
     It do however not define a __len__ attribute because the length
     might be more than Py_ssize_t can handle.
     """
 
     def __init__(self, ui, *args, **kwargs):
         # We can't just "self._data = open(*args, **kwargs)" here because there
         # is an "open" function defined in this module that shadows the global
         # one
         self.ui = ui
         self._data = open(*args, **kwargs)
         self.seek = self._data.seek
         self.close = self._data.close
         self.write = self._data.write
         self.length = os.fstat(self._data.fileno()).st_size
         self._pos = 0
         self._total = self.length // 1024 * 2
 
     def read(self, *args, **kwargs):
         try:
             ret = self._data.read(*args, **kwargs)
         except EOFError:
             self.ui.progress(_('sending'), None)
         self._pos += len(ret)
         # We pass double the max for total because we currently have
         # to send the bundle twice in the case of a server that
         # requires authentication. Since we can't know until we try
         # once whether authentication will be required, just lie to
         # the user and maybe the push succeeds suddenly at 50%.
         self.ui.progress(_('sending'), self._pos // 1024,
                          unit=_('kb'), total=self._total)
         return ret
 
 # moved here from url.py to avoid a cycle
 def readauthforuri(ui, uri, user):
     # Read configuration
     config = dict()
     for key, val in ui.configitems('auth'):
         if '.' not in key:
             ui.warn(_("ignoring invalid [auth] key '%s'\n") % key)
             continue
         group, setting = key.rsplit('.', 1)
         gdict = config.setdefault(group, dict())
         if setting in ('username', 'cert', 'key'):
             val = util.expandpath(val)
         gdict[setting] = val
 
     # Find the best match
     scheme, hostpath = uri.split('://', 1)
     bestuser = None
     bestlen = 0
     bestauth = None
     for group, auth in config.iteritems():
         if user and user != auth.get('username', user):
             # If a username was set in the URI, the entry username
             # must either match it or be unset
             continue
         prefix = auth.get('prefix')
         if not prefix:
             continue
         p = prefix.split('://', 1)
         if len(p) > 1:
             schemes, prefix = [p[0]], p[1]
         else:
             schemes = (auth.get('schemes') or 'https').split()
         if (prefix == '*' or hostpath.startswith(prefix)) and \
             (len(prefix) > bestlen or (len(prefix) == bestlen and \
                 not bestuser and 'username' in auth)) \
              and scheme in schemes:
             bestlen = len(prefix)
             bestauth = group, auth
             bestuser = auth.get('username')
             if user and not bestuser:
                 auth['username'] = user
     return bestauth
 
 # Mercurial (at least until we can remove the old codepath) requires
 # that the http response object be sufficiently file-like, so we
 # provide a close() method here.
 class HTTPResponse(httpclient.HTTPResponse):
     def close(self):
         pass
 
 class HTTPConnection(httpclient.HTTPConnection):
     response_class = HTTPResponse
     def request(self, method, uri, body=None, headers={}):
         if isinstance(body, httpsendfile):
             body.seek(0)
         httpclient.HTTPConnection.request(self, method, uri, body=body,
                                           headers=headers)
 
 
 _configuredlogging = False
 LOGFMT = '%(levelname)s:%(name)s:%(lineno)d:%(message)s'
 # Subclass BOTH of these because otherwise urllib2 "helpfully"
 # reinserts them since it notices we don't include any subclasses of
 # them.
 class http2handler(urllib2.HTTPHandler, urllib2.HTTPSHandler):
     def __init__(self, ui, pwmgr):
         global _configuredlogging
         urllib2.AbstractHTTPHandler.__init__(self)
         self.ui = ui
         self.pwmgr = pwmgr
         self._connections = {}
+        # developer config: ui.http2debuglevel
         loglevel = ui.config('ui', 'http2debuglevel', default=None)
         if loglevel and not _configuredlogging:
             _configuredlogging = True
             logger = logging.getLogger('mercurial.httpclient')
             logger.setLevel(getattr(logging, loglevel.upper()))
             handler = logging.StreamHandler()
             handler.setFormatter(logging.Formatter(LOGFMT))
             logger.addHandler(handler)
 
     def close_all(self):
         """Close and remove all connection objects being kept for reuse."""
         for openconns in self._connections.values():
             for conn in openconns:
                 conn.close()
         self._connections = {}
 
     # shamelessly borrowed from urllib2.AbstractHTTPHandler
     def do_open(self, http_class, req, use_ssl):
         """Return an addinfourl object for the request, using http_class.
 
         http_class must implement the HTTPConnection API from httplib.
         The addinfourl return value is a file-like object.  It also
         has methods and attributes including:
             - info(): return a mimetools.Message object for the headers
             - geturl(): return the original request URL
             - code: HTTP status code
         """
         # If using a proxy, the host returned by get_host() is
         # actually the proxy. On Python 2.6.1, the real destination
         # hostname is encoded in the URI in the urllib2 request
         # object. On Python 2.6.5, it's stored in the _tunnel_host
         # attribute which has no accessor.
         tunhost = getattr(req, '_tunnel_host', None)
         host = req.get_host()
         if tunhost:
             proxyhost = host
             host = tunhost
         elif req.has_proxy():
             proxyhost = req.get_host()
             host = req.get_selector().split('://', 1)[1].split('/', 1)[0]
         else:
             proxyhost = None
 
         if proxyhost:
             if ':' in proxyhost:
                 # Note: this means we'll explode if we try and use an
                 # IPv6 http proxy. This isn't a regression, so we
                 # won't worry about it for now.
                 proxyhost, proxyport = proxyhost.rsplit(':', 1)
             else:
                 proxyport = 3128 # squid default
             proxy = (proxyhost, proxyport)
         else:
             proxy = None
 
         if not host:
             raise urllib2.URLError('no host given')
 
         connkey = use_ssl, host, proxy
         allconns = self._connections.get(connkey, [])
         conns = [c for c in allconns if not c.busy()]
         if conns:
             h = conns[0]
         else:
             if allconns:
                 self.ui.debug('all connections for %s busy, making a new '
                               'one\n' % host)
             timeout = None
             if req.timeout is not socket._GLOBAL_DEFAULT_TIMEOUT:
                 timeout = req.timeout
             h = http_class(host, timeout=timeout, proxy_hostport=proxy)
             self._connections.setdefault(connkey, []).append(h)
 
         headers = dict(req.headers)
         headers.update(req.unredirected_hdrs)
         headers = dict(
             (name.title(), val) for name, val in headers.items())
         try:
             path = req.get_selector()
             if '://' in path:
                 path = path.split('://', 1)[1].split('/', 1)[1]
             if path[0] != '/':
                 path = '/' + path
             h.request(req.get_method(), path, req.data, headers)
             r = h.getresponse()
         except socket.error as err: # XXX what error?
             raise urllib2.URLError(err)
 
         # Pick apart the HTTPResponse object to get the addinfourl
         # object initialized properly.
         r.recv = r.read
 
         resp = urllib.addinfourl(r, r.headers, req.get_full_url())
         resp.code = r.status
         resp.msg = r.reason
         return resp
 
     # httplib always uses the given host/port as the socket connect
     # target, and then allows full URIs in the request path, which it
     # then observes and treats as a signal to do proxying instead.
     def http_open(self, req):
         if req.get_full_url().startswith('https'):
             return self.https_open(req)
         def makehttpcon(*args, **kwargs):
             k2 = dict(kwargs)
             k2['use_ssl'] = False
             return HTTPConnection(*args, **k2)
         return self.do_open(makehttpcon, req, False)
 
     def https_open(self, req):
         # req.get_full_url() does not contain credentials and we may
         # need them to match the certificates.
         url = req.get_full_url()
         user, password = self.pwmgr.find_stored_password(url)
         res = readauthforuri(self.ui, url, user)
         if res:
             group, auth = res
             self.auth = auth
             self.ui.debug("using auth.%s.* for authentication\n" % group)
         else:
             self.auth = None
         return self.do_open(self._makesslconnection, req, True)
 
     def _makesslconnection(self, host, port=443, *args, **kwargs):
         keyfile = None
         certfile = None
 
         if args: # key_file
             keyfile = args.pop(0)
         if args: # cert_file
             certfile = args.pop(0)
 
         # if the user has specified different key/cert files in
         # hgrc, we prefer these
         if self.auth and 'key' in self.auth and 'cert' in self.auth:
             keyfile = self.auth['key']
             certfile = self.auth['cert']
 
         # let host port take precedence
         if ':' in host and '[' not in host or ']:' in host:
             host, port = host.rsplit(':', 1)
             port = int(port)
             if '[' in host:
                 host = host[1:-1]
 
         kwargs['keyfile'] = keyfile
         kwargs['certfile'] = certfile
 
         kwargs.update(sslutil.sslkwargs(self.ui, host))
 
         con = HTTPConnection(host, port, use_ssl=True,
                              ssl_wrap_socket=sslutil.wrapsocket,
                              ssl_validator=sslutil.validator(self.ui, host),
                              **kwargs)
         return con

mercurial/url.py

@@ -1,507 +1,508 b''
 # url.py - HTTP handling for mercurial
 #
 # Copyright 2005, 2006, 2007, 2008 Matt Mackall <[e-mail]>
 # Copyright 2006, 2007 Alexis S. L. Carvalho <[e-mail]>
 # Copyright 2006 Vadim Gelfer <[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.
 
 import urllib, urllib2, httplib, os, socket, cStringIO, base64
 from i18n import _
 import keepalive, util, sslutil
 import httpconnection as httpconnectionmod
 
 class passwordmgr(urllib2.HTTPPasswordMgrWithDefaultRealm):
     def __init__(self, ui):
         urllib2.HTTPPasswordMgrWithDefaultRealm.__init__(self)
         self.ui = ui
 
     def find_user_password(self, realm, authuri):
         authinfo = urllib2.HTTPPasswordMgrWithDefaultRealm.find_user_password(
             self, realm, authuri)
         user, passwd = authinfo
         if user and passwd:
             self._writedebug(user, passwd)
             return (user, passwd)
 
         if not user or not passwd:
             res = httpconnectionmod.readauthforuri(self.ui, authuri, user)
             if res:
                 group, auth = res
                 user, passwd = auth.get('username'), auth.get('password')
                 self.ui.debug("using auth.%s.* for authentication\n" % group)
         if not user or not passwd:
             u = util.url(authuri)
             u.query = None
             if not self.ui.interactive():
                 raise util.Abort(_('http authorization required for %s') %
                                  util.hidepassword(str(u)))
 
             self.ui.write(_("http authorization required for %s\n") %
                           util.hidepassword(str(u)))
             self.ui.write(_("realm: %s\n") % realm)
             if user:
                 self.ui.write(_("user: %s\n") % user)
             else:
                 user = self.ui.prompt(_("user:"), default=None)
 
             if not passwd:
                 passwd = self.ui.getpass()
 
         self.add_password(realm, authuri, user, passwd)
         self._writedebug(user, passwd)
         return (user, passwd)
 
     def _writedebug(self, user, passwd):
         msg = _('http auth: user %s, password %s\n')
         self.ui.debug(msg % (user, passwd and '*' * len(passwd) or 'not set'))
 
     def find_stored_password(self, authuri):
         return urllib2.HTTPPasswordMgrWithDefaultRealm.find_user_password(
             self, None, authuri)
 
 class proxyhandler(urllib2.ProxyHandler):
     def __init__(self, ui):
         proxyurl = ui.config("http_proxy", "host") or os.getenv('http_proxy')
         # XXX proxyauthinfo = None
 
         if proxyurl:
             # proxy can be proper url or host[:port]
             if not (proxyurl.startswith('http:') or
                     proxyurl.startswith('https:')):
                 proxyurl = 'http://' + proxyurl + '/'
             proxy = util.url(proxyurl)
             if not proxy.user:
                 proxy.user = ui.config("http_proxy", "user")
                 proxy.passwd = ui.config("http_proxy", "passwd")
 
             # see if we should use a proxy for this url
             no_list = ["localhost", "127.0.0.1"]
             no_list.extend([p.lower() for
                             p in ui.configlist("http_proxy", "no")])
             no_list.extend([p.strip().lower() for
                             p in os.getenv("no_proxy", '').split(',')
                             if p.strip()])
             # "http_proxy.always" config is for running tests on localhost
             if ui.configbool("http_proxy", "always"):
                 self.no_list = []
             else:
                 self.no_list = no_list
 
             proxyurl = str(proxy)
             proxies = {'http': proxyurl, 'https': proxyurl}
             ui.debug('proxying through http://%s:%s\n' %
                       (proxy.host, proxy.port))
         else:
             proxies = {}
 
         # urllib2 takes proxy values from the environment and those
         # will take precedence if found. So, if there's a config entry
         # defining a proxy, drop the environment ones
         if ui.config("http_proxy", "host"):
             for env in ["HTTP_PROXY", "http_proxy", "no_proxy"]:
                 try:
                     if env in os.environ:
                         del os.environ[env]
                 except OSError:
                     pass
 
         urllib2.ProxyHandler.__init__(self, proxies)
         self.ui = ui
 
     def proxy_open(self, req, proxy, type_):
         host = req.get_host().split(':')[0]
         for e in self.no_list:
             if host == e:
                 return None
             if e.startswith('*.') and host.endswith(e[2:]):
                 return None
             if e.startswith('.') and host.endswith(e[1:]):
                 return None
 
         return urllib2.ProxyHandler.proxy_open(self, req, proxy, type_)
 
 def _gen_sendfile(orgsend):
     def _sendfile(self, data):
         # send a file
         if isinstance(data, httpconnectionmod.httpsendfile):
             # if auth required, some data sent twice, so rewind here
             data.seek(0)
             for chunk in util.filechunkiter(data):
                 orgsend(self, chunk)
         else:
             orgsend(self, data)
     return _sendfile
 
 has_https = util.safehasattr(urllib2, 'HTTPSHandler')
 if has_https:
     try:
         _create_connection = socket.create_connection
     except AttributeError:
         _GLOBAL_DEFAULT_TIMEOUT = object()
 
         def _create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
                                source_address=None):
             # lifted from Python 2.6
 
             msg = "getaddrinfo returns an empty list"
             host, port = address
             for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM):
                 af, socktype, proto, canonname, sa = res
                 sock = None
                 try:
                     sock = socket.socket(af, socktype, proto)
                     if timeout is not _GLOBAL_DEFAULT_TIMEOUT:
                         sock.settimeout(timeout)
                     if source_address:
                         sock.bind(source_address)
                     sock.connect(sa)
                     return sock
 
                 except socket.error as msg:
                     if sock is not None:
                         sock.close()
 
             raise socket.error(msg)
 
 class httpconnection(keepalive.HTTPConnection):
     # must be able to send big bundle as stream.
     send = _gen_sendfile(keepalive.HTTPConnection.send)
 
     def connect(self):
         if has_https and self.realhostport: # use CONNECT proxy
             self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
             self.sock.connect((self.host, self.port))
             if _generic_proxytunnel(self):
                 # we do not support client X.509 certificates
                 self.sock = sslutil.wrapsocket(self.sock, None, None, None,
                                                serverhostname=self.host)
         else:
             keepalive.HTTPConnection.connect(self)
 
     def getresponse(self):
         proxyres = getattr(self, 'proxyres', None)
         if proxyres:
             if proxyres.will_close:
                 self.close()
             self.proxyres = None
             return proxyres
         return keepalive.HTTPConnection.getresponse(self)
 
 # general transaction handler to support different ways to handle
 # HTTPS proxying before and after Python 2.6.3.
 def _generic_start_transaction(handler, h, req):
     tunnel_host = getattr(req, '_tunnel_host', None)
     if tunnel_host:
         if tunnel_host[:7] not in ['http://', 'https:/']:
             tunnel_host = 'https://' + tunnel_host
         new_tunnel = True
     else:
         tunnel_host = req.get_selector()
         new_tunnel = False
 
     if new_tunnel or tunnel_host == req.get_full_url(): # has proxy
         u = util.url(tunnel_host)
         if new_tunnel or u.scheme == 'https': # only use CONNECT for HTTPS
             h.realhostport = ':'.join([u.host, (u.port or '443')])
             h.headers = req.headers.copy()
             h.headers.update(handler.parent.addheaders)
             return
 
     h.realhostport = None
     h.headers = None
 
 def _generic_proxytunnel(self):
     proxyheaders = dict(
             [(x, self.headers[x]) for x in self.headers
              if x.lower().startswith('proxy-')])
     self.send('CONNECT %s HTTP/1.0\r\n' % self.realhostport)
     for header in proxyheaders.iteritems():
         self.send('%s: %s\r\n' % header)
     self.send('\r\n')
 
     # majority of the following code is duplicated from
     # httplib.HTTPConnection as there are no adequate places to
     # override functions to provide the needed functionality
     res = self.response_class(self.sock,
                               strict=self.strict,
                               method=self._method)
 
     while True:
         version, status, reason = res._read_status()
         if status != httplib.CONTINUE:
             break
         while True:
             skip = res.fp.readline().strip()
             if not skip:
                 break
     res.status = status
     res.reason = reason.strip()
 
     if res.status == 200:
         while True:
             line = res.fp.readline()
             if line == '\r\n':
                 break
         return True
 
     if version == 'HTTP/1.0':
         res.version = 10
     elif version.startswith('HTTP/1.'):
         res.version = 11
     elif version == 'HTTP/0.9':
         res.version = 9
     else:
         raise httplib.UnknownProtocol(version)
 
     if res.version == 9:
         res.length = None
         res.chunked = 0
         res.will_close = 1
         res.msg = httplib.HTTPMessage(cStringIO.StringIO())
         return False
 
     res.msg = httplib.HTTPMessage(res.fp)
     res.msg.fp = None
 
     # are we using the chunked-style of transfer encoding?
     trenc = res.msg.getheader('transfer-encoding')
     if trenc and trenc.lower() == "chunked":
         res.chunked = 1
         res.chunk_left = None
     else:
         res.chunked = 0
 
     # will the connection close at the end of the response?
     res.will_close = res._check_close()
 
     # do we have a Content-Length?
     # NOTE: RFC 2616, section 4.4, #3 says we ignore this if
     # transfer-encoding is "chunked"
     length = res.msg.getheader('content-length')
     if length and not res.chunked:
         try:
             res.length = int(length)
         except ValueError:
             res.length = None
         else:
             if res.length < 0:  # ignore nonsensical negative lengths
                 res.length = None
     else:
         res.length = None
 
     # does the body have a fixed length? (of zero)
     if (status == httplib.NO_CONTENT or status == httplib.NOT_MODIFIED or
         100 <= status < 200 or # 1xx codes
         res._method == 'HEAD'):
         res.length = 0
 
     # if the connection remains open, and we aren't using chunked, and
     # a content-length was not provided, then assume that the connection
     # WILL close.
     if (not res.will_close and
        not res.chunked and
        res.length is None):
         res.will_close = 1
 
     self.proxyres = res
 
     return False
 
 class httphandler(keepalive.HTTPHandler):
     def http_open(self, req):
         return self.do_open(httpconnection, req)
 
     def _start_transaction(self, h, req):
         _generic_start_transaction(self, h, req)
         return keepalive.HTTPHandler._start_transaction(self, h, req)
 
 if has_https:
     class httpsconnection(httplib.HTTPConnection):
         response_class = keepalive.HTTPResponse
         default_port = httplib.HTTPS_PORT
         # must be able to send big bundle as stream.
         send = _gen_sendfile(keepalive.safesend)
         getresponse = keepalive.wrapgetresponse(httplib.HTTPConnection)
 
         def __init__(self, host, port=None, key_file=None, cert_file=None,
                      *args, **kwargs):
             httplib.HTTPConnection.__init__(self, host, port, *args, **kwargs)
             self.key_file = key_file
             self.cert_file = cert_file
 
         def connect(self):
             self.sock = _create_connection((self.host, self.port))
 
             host = self.host
             if self.realhostport: # use CONNECT proxy
                 _generic_proxytunnel(self)
                 host = self.realhostport.rsplit(':', 1)[0]
             self.sock = sslutil.wrapsocket(
                 self.sock, self.key_file, self.cert_file, serverhostname=host,
                 **sslutil.sslkwargs(self.ui, host))
             sslutil.validator(self.ui, host)(self.sock)
 
     class httpshandler(keepalive.KeepAliveHandler, urllib2.HTTPSHandler):
         def __init__(self, ui):
             keepalive.KeepAliveHandler.__init__(self)
             urllib2.HTTPSHandler.__init__(self)
             self.ui = ui
             self.pwmgr = passwordmgr(self.ui)
 
         def _start_transaction(self, h, req):
             _generic_start_transaction(self, h, req)
             return keepalive.KeepAliveHandler._start_transaction(self, h, req)
 
         def https_open(self, req):
             # req.get_full_url() does not contain credentials and we may
             # need them to match the certificates.
             url = req.get_full_url()
             user, password = self.pwmgr.find_stored_password(url)
             res = httpconnectionmod.readauthforuri(self.ui, url, user)
             if res:
                 group, auth = res
                 self.auth = auth
                 self.ui.debug("using auth.%s.* for authentication\n" % group)
             else:
                 self.auth = None
             return self.do_open(self._makeconnection, req)
 
         def _makeconnection(self, host, port=None, *args, **kwargs):
             keyfile = None
             certfile = None
 
             if len(args) >= 1: # key_file
                 keyfile = args[0]
             if len(args) >= 2: # cert_file
                 certfile = args[1]
             args = args[2:]
 
             # if the user has specified different key/cert files in
             # hgrc, we prefer these
             if self.auth and 'key' in self.auth and 'cert' in self.auth:
                 keyfile = self.auth['key']
                 certfile = self.auth['cert']
 
             conn = httpsconnection(host, port, keyfile, certfile, *args,
                                    **kwargs)
             conn.ui = self.ui
             return conn
 
 class httpdigestauthhandler(urllib2.HTTPDigestAuthHandler):
     def __init__(self, *args, **kwargs):
         urllib2.HTTPDigestAuthHandler.__init__(self, *args, **kwargs)
         self.retried_req = None
 
     def reset_retry_count(self):
         # Python 2.6.5 will call this on 401 or 407 errors and thus loop
         # forever. We disable reset_retry_count completely and reset in
         # http_error_auth_reqed instead.
         pass
 
     def http_error_auth_reqed(self, auth_header, host, req, headers):
         # Reset the retry counter once for each request.
         if req is not self.retried_req:
             self.retried_req = req
             self.retried = 0
         # In python < 2.5 AbstractDigestAuthHandler raises a ValueError if
         # it doesn't know about the auth type requested. This can happen if
         # somebody is using BasicAuth and types a bad password.
         try:
             return urllib2.HTTPDigestAuthHandler.http_error_auth_reqed(
                         self, auth_header, host, req, headers)
         except ValueError as inst:
             arg = inst.args[0]
             if arg.startswith("AbstractDigestAuthHandler doesn't know "):
                 return
             raise
 
 class httpbasicauthhandler(urllib2.HTTPBasicAuthHandler):
     def __init__(self, *args, **kwargs):
         self.auth = None
         urllib2.HTTPBasicAuthHandler.__init__(self, *args, **kwargs)
         self.retried_req = None
 
     def http_request(self, request):
         if self.auth:
             request.add_unredirected_header(self.auth_header, self.auth)
 
         return request
 
     def https_request(self, request):
         if self.auth:
             request.add_unredirected_header(self.auth_header, self.auth)
 
         return request
 
     def reset_retry_count(self):
         # Python 2.6.5 will call this on 401 or 407 errors and thus loop
         # forever. We disable reset_retry_count completely and reset in
         # http_error_auth_reqed instead.
         pass
 
     def http_error_auth_reqed(self, auth_header, host, req, headers):
         # Reset the retry counter once for each request.
         if req is not self.retried_req:
             self.retried_req = req
             self.retried = 0
         return urllib2.HTTPBasicAuthHandler.http_error_auth_reqed(
                         self, auth_header, host, req, headers)
 
     def retry_http_basic_auth(self, host, req, realm):
         user, pw = self.passwd.find_user_password(realm, req.get_full_url())
         if pw is not None:
             raw = "%s:%s" % (user, pw)
             auth = 'Basic %s' % base64.b64encode(raw).strip()
             if req.headers.get(self.auth_header, None) == auth:
                 return None
             self.auth = auth
             req.add_unredirected_header(self.auth_header, auth)
             return self.parent.open(req)
         else:
             return None
 
 handlerfuncs = []
 
 def opener(ui, authinfo=None):
     '''
     construct an opener suitable for urllib2
     authinfo will be added to the password manager
     '''
+    # experimental config: ui.usehttp2
     if ui.configbool('ui', 'usehttp2', False):
         handlers = [httpconnectionmod.http2handler(ui, passwordmgr(ui))]
     else:
         handlers = [httphandler()]
         if has_https:
             handlers.append(httpshandler(ui))
 
     handlers.append(proxyhandler(ui))
 
     passmgr = passwordmgr(ui)
     if authinfo is not None:
         passmgr.add_password(*authinfo)
         user, passwd = authinfo[2:4]
         ui.debug('http auth: user %s, password %s\n' %
                  (user, passwd and '*' * len(passwd) or 'not set'))
 
     handlers.extend((httpbasicauthhandler(passmgr),
                      httpdigestauthhandler(passmgr)))
     handlers.extend([h(ui, passmgr) for h in handlerfuncs])
     opener = urllib2.build_opener(*handlers)
 
     # 1.0 here is the _protocol_ version
     opener.addheaders = [('User-agent', 'mercurial/proto-1.0')]
     opener.addheaders.append(('Accept', 'application/mercurial-0.1'))
     return opener
 
 def open(ui, url_, data=None):
     u = util.url(url_)
     if u.scheme:
         u.scheme = u.scheme.lower()
         url_, authinfo = u.authinfo()
     else:
         path = util.normpath(os.path.abspath(url_))
         url_ = 'file://' + urllib.pathname2url(path)
         authinfo = None
     return opener(ui, authinfo).open(url_, data)