httprepo: use separate handlers for HTTP and HTTPS

This is needed to keep the code in keepalive.py from sharing
the same connection between HTTP and HTTPS.

52ce0d6bc375 explains why we were using a single handler.

This should fix issue892.

mercurial/httprepo.py

@@ -1,459 +1,458
 # httprepo.py - HTTP repository proxy classes for mercurial
 #
 # Copyright 2005, 2006 Matt Mackall <[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, incorporated herein by reference.
 
 from node import *
 from remoterepo import *
 from i18n import _
 import repo, os, urllib, urllib2, urlparse, zlib, util, httplib
 import errno, keepalive, tempfile, socket, changegroup
 
 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:
             return (user, passwd)
 
         if not self.ui.interactive:
             raise util.Abort(_('http authorization required'))
 
         self.ui.write(_("http authorization required\n"))
         self.ui.status(_("realm: %s\n") % realm)
         if user:
             self.ui.status(_("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)
         return (user, passwd)
 
 def netlocsplit(netloc):
     '''split [user[:passwd]@]host[:port] into 4-tuple.'''
 
     a = netloc.find('@')
     if a == -1:
         user, passwd = None, None
     else:
         userpass, netloc = netloc[:a], netloc[a+1:]
         c = userpass.find(':')
         if c == -1:
             user, passwd = urllib.unquote(userpass), None
         else:
             user = urllib.unquote(userpass[:c])
             passwd = urllib.unquote(userpass[c+1:])
     c = netloc.find(':')
     if c == -1:
         host, port = netloc, None
     else:
         host, port = netloc[:c], netloc[c+1:]
     return host, port, user, passwd
 
 def netlocunsplit(host, port, user=None, passwd=None):
     '''turn host, port, user, passwd into [user[:passwd]@]host[:port].'''
     if port:
         hostport = host + ':' + port
     else:
         hostport = host
     if user:
         if passwd:
             userpass = urllib.quote(user) + ':' + urllib.quote(passwd)
         else:
             userpass = urllib.quote(user)
         return userpass + '@' + hostport
     return hostport
 
 # work around a bug in Python < 2.4.2
 # (it leaves a "\n" at the end of Proxy-authorization headers)
 class request(urllib2.Request):
     def add_header(self, key, val):
         if key.lower() == 'proxy-authorization':
             val = val.strip()
         return urllib2.Request.add_header(self, key, val)
 
 class httpsendfile(file):
     def __len__(self):
         return os.fstat(self.fileno()).st_size
 
 def _gen_sendfile(connection):
     def _sendfile(self, data):
         # send a file
         if isinstance(data, httpsendfile):
             # if auth required, some data sent twice, so rewind here
             data.seek(0)
             for chunk in util.filechunkiter(data):
                 connection.send(self, chunk)
         else:
             connection.send(self, data)
     return _sendfile
 
 class httpconnection(keepalive.HTTPConnection):
     # must be able to send big bundle as stream.
     send = _gen_sendfile(keepalive.HTTPConnection)
 
-class basehttphandler(keepalive.HTTPHandler):
+class httphandler(keepalive.HTTPHandler):
     def http_open(self, req):
         return self.do_open(httpconnection, req)
 
     def __del__(self):
         self.close_all()
 
 has_https = hasattr(urllib2, 'HTTPSHandler')
 if has_https:
     class httpsconnection(httplib.HTTPSConnection):
         response_class = keepalive.HTTPResponse
         # must be able to send big bundle as stream.
         send = _gen_sendfile(httplib.HTTPSConnection)
 
-    class httphandler(basehttphandler, urllib2.HTTPSHandler):
+    class httpshandler(keepalive.KeepAliveHandler, urllib2.HTTPSHandler):
         def https_open(self, req):
             return self.do_open(httpsconnection, req)
-else:
-    class httphandler(basehttphandler):
-        pass
 
 # 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.
 class httpdigestauthhandler(urllib2.HTTPDigestAuthHandler):
     def http_error_auth_reqed(self, auth_header, host, req, headers):
         try:
             return urllib2.HTTPDigestAuthHandler.http_error_auth_reqed(
                         self, auth_header, host, req, headers)
         except ValueError, inst:
             arg = inst.args[0]
             if arg.startswith("AbstractDigestAuthHandler doesn't know "):
                 return
             raise
 
 def zgenerator(f):
     zd = zlib.decompressobj()
     try:
         for chunk in util.filechunkiter(f):
             yield zd.decompress(chunk)
     except httplib.HTTPException, inst:
         raise IOError(None, _('connection ended unexpectedly'))
     yield zd.flush()
 
 _safe = ('abcdefghijklmnopqrstuvwxyz'
          'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
          '0123456789' '_.-/')
 _safeset = None
 _hex = None
 def quotepath(path):
     '''quote the path part of a URL
 
     This is similar to urllib.quote, but it also tries to avoid
     quoting things twice (inspired by wget):
 
     >>> quotepath('abc def')
     'abc%20def'
     >>> quotepath('abc%20def')
     'abc%20def'
     >>> quotepath('abc%20 def')
     'abc%20%20def'
     >>> quotepath('abc def%20')
     'abc%20def%20'
     >>> quotepath('abc def%2')
     'abc%20def%252'
     >>> quotepath('abc def%')
     'abc%20def%25'
     '''
     global _safeset, _hex
     if _safeset is None:
         _safeset = util.set(_safe)
         _hex = util.set('abcdefABCDEF0123456789')
     l = list(path)
     for i in xrange(len(l)):
         c = l[i]
         if c == '%' and i + 2 < len(l) and (l[i+1] in _hex and l[i+2] in _hex):
             pass
         elif c not in _safeset:
             l[i] = '%%%02X' % ord(c)
     return ''.join(l)
 
 class httprepository(remoterepository):
     def __init__(self, ui, path):
         self.path = path
         self.caps = None
         self.handler = None
         scheme, netloc, urlpath, query, frag = urlparse.urlsplit(path)
         if query or frag:
             raise util.Abort(_('unsupported URL component: "%s"') %
                              (query or frag))
         if not urlpath:
             urlpath = '/'
         urlpath = quotepath(urlpath)
         host, port, user, passwd = netlocsplit(netloc)
 
         # urllib cannot handle URLs with embedded user or passwd
         self._url = urlparse.urlunsplit((scheme, netlocunsplit(host, port),
                                          urlpath, '', ''))
         self.ui = ui
         self.ui.debug(_('using %s\n') % self._url)
 
         proxyurl = ui.config("http_proxy", "host") or os.getenv('http_proxy')
         # XXX proxyauthinfo = None
         handlers = [httphandler()]
+        if has_https:
+            handlers.append(httpshandler())
 
         if proxyurl:
             # proxy can be proper url or host[:port]
             if not (proxyurl.startswith('http:') or
                     proxyurl.startswith('https:')):
                 proxyurl = 'http://' + proxyurl + '/'
             snpqf = urlparse.urlsplit(proxyurl)
             proxyscheme, proxynetloc, proxypath, proxyquery, proxyfrag = snpqf
             hpup = netlocsplit(proxynetloc)
 
             proxyhost, proxyport, proxyuser, proxypasswd = hpup
             if not proxyuser:
                 proxyuser = ui.config("http_proxy", "user")
                 proxypasswd = 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 (not ui.configbool("http_proxy", "always") and
                 host.lower() in no_list):
                 # avoid auto-detection of proxy settings by appending
                 # a ProxyHandler with no proxies defined.
                 handlers.append(urllib2.ProxyHandler({}))
                 ui.debug(_('disabling proxy for %s\n') % host)
             else:
                 proxyurl = urlparse.urlunsplit((
                     proxyscheme, netlocunsplit(proxyhost, proxyport,
                                                proxyuser, proxypasswd or ''),
                     proxypath, proxyquery, proxyfrag))
                 handlers.append(urllib2.ProxyHandler({scheme: proxyurl}))
                 ui.debug(_('proxying through http://%s:%s\n') %
                           (proxyhost, proxyport))
 
         # urllib2 takes proxy values from the environment and those
         # will take precedence if found, so drop them
         for env in ["HTTP_PROXY", "http_proxy", "no_proxy"]:
             try:
                 if os.environ.has_key(env):
                     del os.environ[env]
             except OSError:
                 pass
 
         passmgr = passwordmgr(ui)
         if user:
             ui.debug(_('http auth: user %s, password %s\n') %
                      (user, passwd and '*' * len(passwd) or 'not set'))
             netloc = host
             if port:
                 netloc += ':' + port
             # Python < 2.4.3 uses only the netloc to search for a password
             passmgr.add_password(None, (self._url, netloc), user, passwd or '')
 
         handlers.extend((urllib2.HTTPBasicAuthHandler(passmgr),
                          httpdigestauthhandler(passmgr)))
         opener = urllib2.build_opener(*handlers)
 
         # 1.0 here is the _protocol_ version
         opener.addheaders = [('User-agent', 'mercurial/proto-1.0')]
         urllib2.install_opener(opener)
 
     def url(self):
         return self.path
 
     # look up capabilities only when needed
 
     def get_caps(self):
         if self.caps is None:
             try:
                 self.caps = util.set(self.do_read('capabilities').split())
             except repo.RepoError:
                 self.caps = util.set()
             self.ui.debug(_('capabilities: %s\n') %
                           (' '.join(self.caps or ['none'])))
         return self.caps
 
     capabilities = property(get_caps)
 
     def lock(self):
         raise util.Abort(_('operation not supported over http'))
 
     def do_cmd(self, cmd, **args):
         data = args.pop('data', None)
         headers = args.pop('headers', {})
         self.ui.debug(_("sending %s command\n") % cmd)
         q = {"cmd": cmd}
         q.update(args)
         qs = '?%s' % urllib.urlencode(q)
         cu = "%s%s" % (self._url, qs)
         try:
             if data:
                 self.ui.debug(_("sending %s bytes\n") % len(data))
             resp = urllib2.urlopen(request(cu, data, headers))
         except urllib2.HTTPError, inst:
             if inst.code == 401:
                 raise util.Abort(_('authorization failed'))
             raise
         except httplib.HTTPException, inst:
             self.ui.debug(_('http error while sending %s command\n') % cmd)
             self.ui.print_exc()
             raise IOError(None, inst)
         except IndexError:
             # this only happens with Python 2.3, later versions raise URLError
             raise util.Abort(_('http error, possibly caused by proxy setting'))
         # record the url we got redirected to
         resp_url = resp.geturl()
         if resp_url.endswith(qs):
             resp_url = resp_url[:-len(qs)]
         if self._url != resp_url:
             self.ui.status(_('real URL is %s\n') % resp_url)
             self._url = resp_url
         try:
             proto = resp.getheader('content-type')
         except AttributeError:
             proto = resp.headers['content-type']
 
         # accept old "text/plain" and "application/hg-changegroup" for now
         if not (proto.startswith('application/mercurial-') or
                 proto.startswith('text/plain') or
                 proto.startswith('application/hg-changegroup')):
             self.ui.debug(_("Requested URL: '%s'\n") % cu)
             raise repo.RepoError(_("'%s' does not appear to be an hg repository")
                                % self._url)
 
         if proto.startswith('application/mercurial-'):
             try:
                 version = proto.split('-', 1)[1]
                 version_info = tuple([int(n) for n in version.split('.')])
             except ValueError:
                 raise repo.RepoError(_("'%s' sent a broken Content-type "
                                      "header (%s)") % (self._url, proto))
             if version_info > (0, 1):
                 raise repo.RepoError(_("'%s' uses newer protocol %s") %
                                    (self._url, version))
 
         return resp
 
     def do_read(self, cmd, **args):
         fp = self.do_cmd(cmd, **args)
         try:
             return fp.read()
         finally:
             # if using keepalive, allow connection to be reused
             fp.close()
 
     def lookup(self, key):
         self.requirecap('lookup', _('look up remote revision'))
         d = self.do_cmd("lookup", key = key).read()
         success, data = d[:-1].split(' ', 1)
         if int(success):
             return bin(data)
         raise repo.RepoError(data)
 
     def heads(self):
         d = self.do_read("heads")
         try:
             return map(bin, d[:-1].split(" "))
         except:
             raise util.UnexpectedOutput(_("unexpected response:"), d)
 
     def branches(self, nodes):
         n = " ".join(map(hex, nodes))
         d = self.do_read("branches", nodes=n)
         try:
             br = [ tuple(map(bin, b.split(" "))) for b in d.splitlines() ]
             return br
         except:
             raise util.UnexpectedOutput(_("unexpected response:"), d)
 
     def between(self, pairs):
         n = "\n".join(["-".join(map(hex, p)) for p in pairs])
         d = self.do_read("between", pairs=n)
         try:
             p = [ l and map(bin, l.split(" ")) or [] for l in d.splitlines() ]
             return p
         except:
             raise util.UnexpectedOutput(_("unexpected response:"), d)
 
     def changegroup(self, nodes, kind):
         n = " ".join(map(hex, nodes))
         f = self.do_cmd("changegroup", roots=n)
         return util.chunkbuffer(zgenerator(f))
 
     def changegroupsubset(self, bases, heads, source):
         self.requirecap('changegroupsubset', _('look up remote changes'))
         baselst = " ".join([hex(n) for n in bases])
         headlst = " ".join([hex(n) for n in heads])
         f = self.do_cmd("changegroupsubset", bases=baselst, heads=headlst)
         return util.chunkbuffer(zgenerator(f))
 
     def unbundle(self, cg, heads, source):
         # have to stream bundle to a temp file because we do not have
         # http 1.1 chunked transfer.
 
         type = ""
         types = self.capable('unbundle')
         # servers older than d1b16a746db6 will send 'unbundle' as a
         # boolean capability
         try:
             types = types.split(',')
         except AttributeError:
             types = [""]
         if types:
             for x in types:
                 if x in changegroup.bundletypes:
                     type = x
                     break
 
         tempname = changegroup.writebundle(cg, None, type)
         fp = httpsendfile(tempname, "rb")
         try:
             try:
                 rfp = self.do_cmd(
                     'unbundle', data=fp,
                     headers={'content-type': 'application/octet-stream'},
                     heads=' '.join(map(hex, heads)))
                 try:
                     ret = int(rfp.readline())
                     self.ui.write(rfp.read())
                     return ret
                 finally:
                     rfp.close()
             except socket.error, err:
                 if err[0] in (errno.ECONNRESET, errno.EPIPE):
                     raise util.Abort(_('push failed: %s') % err[1])
                 raise util.Abort(err[1])
         finally:
             fp.close()
             os.unlink(tempname)
 
     def stream_out(self):
         return self.do_cmd('stream_out')
 
 class httpsrepository(httprepository):
     def __init__(self, ui, path):
         if not has_https:
             raise util.Abort(_('Python support for SSL and HTTPS '
                                'is not installed'))
         httprepository.__init__(self, ui, path)
 
 def instance(ui, path, create):
     if create:
         raise util.Abort(_('cannot create new http repository'))
     if path.startswith('https:'):
         return httpsrepository(ui, path)
     return httprepository(ui, path)

mercurial/keepalive.py

@@ -1,579 +1,582
 #   This library is free software; you can redistribute it and/or
 #   modify it under the terms of the GNU Lesser General Public
 #   License as published by the Free Software Foundation; either
 #   version 2.1 of the License, or (at your option) any later version.
 #
 #   This library is distributed in the hope that it will be useful,
 #   but WITHOUT ANY WARRANTY; without even the implied warranty of
 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 #   Lesser General Public License for more details.
 #
 #   You should have received a copy of the GNU Lesser General Public
 #   License along with this library; if not, write to the
 #      Free Software Foundation, Inc.,
 #      59 Temple Place, Suite 330,
 #      Boston, MA  02111-1307  USA
 
 # This file is part of urlgrabber, a high-level cross-protocol url-grabber
 # Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko
 
 # Modified by Benoit Boissinot:
 #  - fix for digest auth (inspired from urllib2.py @ Python v2.4)
 
 """An HTTP handler for urllib2 that supports HTTP 1.1 and keepalive.
 
 >>> import urllib2
 >>> from keepalive import HTTPHandler
 >>> keepalive_handler = HTTPHandler()
 >>> opener = urllib2.build_opener(keepalive_handler)
 >>> urllib2.install_opener(opener)
 >>>
 >>> fo = urllib2.urlopen('http://www.python.org')
 
 If a connection to a given host is requested, and all of the existing
 connections are still in use, another connection will be opened.  If
 the handler tries to use an existing connection but it fails in some
 way, it will be closed and removed from the pool.
 
 To remove the handler, simply re-run build_opener with no arguments, and
 install that opener.
 
 You can explicitly close connections by using the close_connection()
 method of the returned file-like object (described below) or you can
 use the handler methods:
 
   close_connection(host)
   close_all()
   open_connections()
 
 NOTE: using the close_connection and close_all methods of the handler
 should be done with care when using multiple threads.
   * there is nothing that prevents another thread from creating new
     connections immediately after connections are closed
   * no checks are done to prevent in-use connections from being closed
 
 >>> keepalive_handler.close_all()
 
 EXTRA ATTRIBUTES AND METHODS
 
   Upon a status of 200, the object returned has a few additional
   attributes and methods, which should not be used if you want to
   remain consistent with the normal urllib2-returned objects:
 
     close_connection()  -  close the connection to the host
     readlines()         -  you know, readlines()
     status              -  the return status (ie 404)
     reason              -  english translation of status (ie 'File not found')
 
   If you want the best of both worlds, use this inside an
   AttributeError-catching try:
 
   >>> try: status = fo.status
   >>> except AttributeError: status = None
 
   Unfortunately, these are ONLY there if status == 200, so it's not
   easy to distinguish between non-200 responses.  The reason is that
   urllib2 tries to do clever things with error codes 301, 302, 401,
   and 407, and it wraps the object upon return.
 
   For python versions earlier than 2.4, you can avoid this fancy error
   handling by setting the module-level global HANDLE_ERRORS to zero.
   You see, prior to 2.4, it's the HTTP Handler's job to determine what
   to handle specially, and what to just pass up.  HANDLE_ERRORS == 0
   means "pass everything up".  In python 2.4, however, this job no
   longer belongs to the HTTP Handler and is now done by a NEW handler,
   HTTPErrorProcessor.  Here's the bottom line:
 
     python version < 2.4
         HANDLE_ERRORS == 1  (default) pass up 200, treat the rest as
                             errors
         HANDLE_ERRORS == 0  pass everything up, error processing is
                             left to the calling code
     python version >= 2.4
         HANDLE_ERRORS == 1  pass up 200, treat the rest as errors
         HANDLE_ERRORS == 0  (default) pass everything up, let the
                             other handlers (specifically,
                             HTTPErrorProcessor) decide what to do
 
   In practice, setting the variable either way makes little difference
   in python 2.4, so for the most consistent behavior across versions,
   you probably just want to use the defaults, which will give you
   exceptions on errors.
 
 """
 
 # $Id: keepalive.py,v 1.14 2006/04/04 21:00:32 mstenner Exp $
 
 import urllib2
 import httplib
 import socket
 import thread
 
 DEBUG = None
 
 import sys
 if sys.version_info < (2, 4): HANDLE_ERRORS = 1
 else: HANDLE_ERRORS = 0
 
 class ConnectionManager:
     """
     The connection manager must be able to:
       * keep track of all existing
       """
     def __init__(self):
         self._lock = thread.allocate_lock()
         self._hostmap = {} # map hosts to a list of connections
         self._connmap = {} # map connections to host
         self._readymap = {} # map connection to ready state
 
     def add(self, host, connection, ready):
         self._lock.acquire()
         try:
             if not self._hostmap.has_key(host): self._hostmap[host] = []
             self._hostmap[host].append(connection)
             self._connmap[connection] = host
             self._readymap[connection] = ready
         finally:
             self._lock.release()
 
     def remove(self, connection):
         self._lock.acquire()
         try:
             try:
                 host = self._connmap[connection]
             except KeyError:
                 pass
             else:
                 del self._connmap[connection]
                 del self._readymap[connection]
                 self._hostmap[host].remove(connection)
                 if not self._hostmap[host]: del self._hostmap[host]
         finally:
             self._lock.release()
 
     def set_ready(self, connection, ready):
         try: self._readymap[connection] = ready
         except KeyError: pass
 
     def get_ready_conn(self, host):
         conn = None
         self._lock.acquire()
         try:
             if self._hostmap.has_key(host):
                 for c in self._hostmap[host]:
                     if self._readymap[c]:
                         self._readymap[c] = 0
                         conn = c
                         break
         finally:
             self._lock.release()
         return conn
 
     def get_all(self, host=None):
         if host:
             return list(self._hostmap.get(host, []))
         else:
             return dict(self._hostmap)
 
-class HTTPHandler(urllib2.HTTPHandler):
+class KeepAliveHandler:
     def __init__(self):
         self._cm = ConnectionManager()
 
     #### Connection Management
     def open_connections(self):
         """return a list of connected hosts and the number of connections
         to each.  [('foo.com:80', 2), ('bar.org', 1)]"""
         return [(host, len(li)) for (host, li) in self._cm.get_all().items()]
 
     def close_connection(self, host):
         """close connection(s) to <host>
         host is the host:port spec, as in 'www.cnn.com:8080' as passed in.
         no error occurs if there is no connection to that host."""
         for h in self._cm.get_all(host):
             self._cm.remove(h)
             h.close()
 
     def close_all(self):
         """close all open connections"""
         for host, conns in self._cm.get_all().items():
             for h in conns:
                 self._cm.remove(h)
                 h.close()
 
     def _request_closed(self, request, host, connection):
         """tells us that this request is now closed and the the
         connection is ready for another request"""
         self._cm.set_ready(connection, 1)
 
     def _remove_connection(self, host, connection, close=0):
         if close: connection.close()
         self._cm.remove(connection)
 
     #### Transaction Execution
     def http_open(self, req):
         return self.do_open(HTTPConnection, req)
 
     def do_open(self, http_class, req):
         host = req.get_host()
         if not host:
             raise urllib2.URLError('no host given')
 
         try:
             h = self._cm.get_ready_conn(host)
             while h:
                 r = self._reuse_connection(h, req, host)
 
                 # if this response is non-None, then it worked and we're
                 # done.  Break out, skipping the else block.
                 if r: break
 
                 # connection is bad - possibly closed by server
                 # discard it and ask for the next free connection
                 h.close()
                 self._cm.remove(h)
                 h = self._cm.get_ready_conn(host)
             else:
                 # no (working) free connections were found.  Create a new one.
                 h = http_class(host)
                 if DEBUG: DEBUG.info("creating new connection to %s (%d)",
                                      host, id(h))
                 self._cm.add(host, h, 0)
                 self._start_transaction(h, req)
                 r = h.getresponse()
         except (socket.error, httplib.HTTPException), err:
             raise urllib2.URLError(err)
 
         # if not a persistent connection, don't try to reuse it
         if r.will_close: self._cm.remove(h)
 
         if DEBUG: DEBUG.info("STATUS: %s, %s", r.status, r.reason)
         r._handler = self
         r._host = host
         r._url = req.get_full_url()
         r._connection = h
         r.code = r.status
         r.headers = r.msg
         r.msg = r.reason
 
         if r.status == 200 or not HANDLE_ERRORS:
             return r
         else:
             return self.parent.error('http', req, r,
                                      r.status, r.msg, r.headers)
 
     def _reuse_connection(self, h, req, host):
         """start the transaction with a re-used connection
         return a response object (r) upon success or None on failure.
         This DOES not close or remove bad connections in cases where
         it returns.  However, if an unexpected exception occurs, it
         will close and remove the connection before re-raising.
         """
         try:
             self._start_transaction(h, req)
             r = h.getresponse()
             # note: just because we got something back doesn't mean it
             # worked.  We'll check the version below, too.
         except (socket.error, httplib.HTTPException):
             r = None
         except:
             # adding this block just in case we've missed
             # something we will still raise the exception, but
             # lets try and close the connection and remove it
             # first.  We previously got into a nasty loop
             # where an exception was uncaught, and so the
             # connection stayed open.  On the next try, the
             # same exception was raised, etc.  The tradeoff is
             # that it's now possible this call will raise
             # a DIFFERENT exception
             if DEBUG: DEBUG.error("unexpected exception - closing " + \
                                   "connection to %s (%d)", host, id(h))
             self._cm.remove(h)
             h.close()
             raise
 
         if r is None or r.version == 9:
             # httplib falls back to assuming HTTP 0.9 if it gets a
             # bad header back.  This is most likely to happen if
             # the socket has been closed by the server since we
             # last used the connection.
             if DEBUG: DEBUG.info("failed to re-use connection to %s (%d)",
                                  host, id(h))
             r = None
         else:
             if DEBUG: DEBUG.info("re-using connection to %s (%d)", host, id(h))
 
         return r
 
     def _start_transaction(self, h, req):
         headers = req.headers.copy()
         body = req.data
         if sys.version_info >= (2, 4):
             headers.update(req.unredirected_hdrs)
         try:
             h.request(req.get_method(), req.get_selector(), body, headers)
         except socket.error, err: # XXX what error?
             raise urllib2.URLError(err)
 
+class HTTPHandler(KeepAliveHandler, urllib2.HTTPHandler):
+    pass
+
 class HTTPResponse(httplib.HTTPResponse):
     # we need to subclass HTTPResponse in order to
     # 1) add readline() and readlines() methods
     # 2) add close_connection() methods
     # 3) add info() and geturl() methods
 
     # in order to add readline(), read must be modified to deal with a
     # buffer.  example: readline must read a buffer and then spit back
     # one line at a time.  The only real alternative is to read one
     # BYTE at a time (ick).  Once something has been read, it can't be
     # put back (ok, maybe it can, but that's even uglier than this),
     # so if you THEN do a normal read, you must first take stuff from
     # the buffer.
 
     # the read method wraps the original to accomodate buffering,
     # although read() never adds to the buffer.
     # Both readline and readlines have been stolen with almost no
     # modification from socket.py
 
 
     def __init__(self, sock, debuglevel=0, strict=0, method=None):
         if method: # the httplib in python 2.3 uses the method arg
             httplib.HTTPResponse.__init__(self, sock, debuglevel, method)
         else: # 2.2 doesn't
             httplib.HTTPResponse.__init__(self, sock, debuglevel)
         self.fileno = sock.fileno
         self.code = None
         self._rbuf = ''
         self._rbufsize = 8096
         self._handler = None # inserted by the handler later
         self._host = None    # (same)
         self._url = None     # (same)
         self._connection = None # (same)
 
     _raw_read = httplib.HTTPResponse.read
 
     def close(self):
         if self.fp:
             self.fp.close()
             self.fp = None
             if self._handler:
                 self._handler._request_closed(self, self._host,
                                               self._connection)
 
     def close_connection(self):
         self._handler._remove_connection(self._host, self._connection, close=1)
         self.close()
 
     def info(self):
         return self.headers
 
     def geturl(self):
         return self._url
 
     def read(self, amt=None):
         # the _rbuf test is only in this first if for speed.  It's not
         # logically necessary
         if self._rbuf and not amt is None:
             L = len(self._rbuf)
             if amt > L:
                 amt -= L
             else:
                 s = self._rbuf[:amt]
                 self._rbuf = self._rbuf[amt:]
                 return s
 
         s = self._rbuf + self._raw_read(amt)
         self._rbuf = ''
         return s
 
     def readline(self, limit=-1):
         data = ""
         i = self._rbuf.find('\n')
         while i < 0 and not (0 < limit <= len(self._rbuf)):
             new = self._raw_read(self._rbufsize)
             if not new: break
             i = new.find('\n')
             if i >= 0: i = i + len(self._rbuf)
             self._rbuf = self._rbuf + new
         if i < 0: i = len(self._rbuf)
         else: i = i+1
         if 0 <= limit < len(self._rbuf): i = limit
         data, self._rbuf = self._rbuf[:i], self._rbuf[i:]
         return data
 
     def readlines(self, sizehint = 0):
         total = 0
         list = []
         while 1:
             line = self.readline()
             if not line: break
             list.append(line)
             total += len(line)
             if sizehint and total >= sizehint:
                 break
         return list
 
 
 class HTTPConnection(httplib.HTTPConnection):
     # use the modified response class
     response_class = HTTPResponse
 
 #########################################################################
 #####   TEST FUNCTIONS
 #########################################################################
 
 def error_handler(url):
     global HANDLE_ERRORS
     orig = HANDLE_ERRORS
     keepalive_handler = HTTPHandler()
     opener = urllib2.build_opener(keepalive_handler)
     urllib2.install_opener(opener)
     pos = {0: 'off', 1: 'on'}
     for i in (0, 1):
         print "  fancy error handling %s (HANDLE_ERRORS = %i)" % (pos[i], i)
         HANDLE_ERRORS = i
         try:
             fo = urllib2.urlopen(url)
             foo = fo.read()
             fo.close()
             try: status, reason = fo.status, fo.reason
             except AttributeError: status, reason = None, None
         except IOError, e:
             print "  EXCEPTION: %s" % e
             raise
         else:
             print "  status = %s, reason = %s" % (status, reason)
     HANDLE_ERRORS = orig
     hosts = keepalive_handler.open_connections()
     print "open connections:", hosts
     keepalive_handler.close_all()
 
 def continuity(url):
     import md5
     format = '%25s: %s'
 
     # first fetch the file with the normal http handler
     opener = urllib2.build_opener()
     urllib2.install_opener(opener)
     fo = urllib2.urlopen(url)
     foo = fo.read()
     fo.close()
     m = md5.new(foo)
     print format % ('normal urllib', m.hexdigest())
 
     # now install the keepalive handler and try again
     opener = urllib2.build_opener(HTTPHandler())
     urllib2.install_opener(opener)
 
     fo = urllib2.urlopen(url)
     foo = fo.read()
     fo.close()
     m = md5.new(foo)
     print format % ('keepalive read', m.hexdigest())
 
     fo = urllib2.urlopen(url)
     foo = ''
     while 1:
         f = fo.readline()
         if f: foo = foo + f
         else: break
     fo.close()
     m = md5.new(foo)
     print format % ('keepalive readline', m.hexdigest())
 
 def comp(N, url):
     print '  making %i connections to:\n  %s' % (N, url)
 
     sys.stdout.write('  first using the normal urllib handlers')
     # first use normal opener
     opener = urllib2.build_opener()
     urllib2.install_opener(opener)
     t1 = fetch(N, url)
     print '  TIME: %.3f s' % t1
 
     sys.stdout.write('  now using the keepalive handler       ')
     # now install the keepalive handler and try again
     opener = urllib2.build_opener(HTTPHandler())
     urllib2.install_opener(opener)
     t2 = fetch(N, url)
     print '  TIME: %.3f s' % t2
     print '  improvement factor: %.2f' % (t1/t2, )
 
 def fetch(N, url, delay=0):
     import time
     lens = []
     starttime = time.time()
     for i in range(N):
         if delay and i > 0: time.sleep(delay)
         fo = urllib2.urlopen(url)
         foo = fo.read()
         fo.close()
         lens.append(len(foo))
     diff = time.time() - starttime
 
     j = 0
     for i in lens[1:]:
         j = j + 1
         if not i == lens[0]:
             print "WARNING: inconsistent length on read %i: %i" % (j, i)
 
     return diff
 
 def test_timeout(url):
     global DEBUG
     dbbackup = DEBUG
     class FakeLogger:
         def debug(self, msg, *args): print msg % args
         info = warning = error = debug
     DEBUG = FakeLogger()
     print "  fetching the file to establish a connection"
     fo = urllib2.urlopen(url)
     data1 = fo.read()
     fo.close()
 
     i = 20
     print "  waiting %i seconds for the server to close the connection" % i
     while i > 0:
         sys.stdout.write('\r  %2i' % i)
         sys.stdout.flush()
         time.sleep(1)
         i -= 1
     sys.stderr.write('\r')
 
     print "  fetching the file a second time"
     fo = urllib2.urlopen(url)
     data2 = fo.read()
     fo.close()
 
     if data1 == data2:
         print '  data are identical'
     else:
         print '  ERROR: DATA DIFFER'
 
     DEBUG = dbbackup
 
 
 def test(url, N=10):
     print "checking error hander (do this on a non-200)"
     try: error_handler(url)
     except IOError, e:
         print "exiting - exception will prevent further tests"
         sys.exit()
     print
     print "performing continuity test (making sure stuff isn't corrupted)"
     continuity(url)
     print
     print "performing speed comparison"
     comp(N, url)
     print
     print "performing dropped-connection check"
     test_timeout(url)
 
 if __name__ == '__main__':
     import time
     import sys
     try:
         N = int(sys.argv[1])
         url = sys.argv[2]
     except:
         print "%s <integer> <url>" % sys.argv[0]
     else:
         test(url, N)