url: use CONNECT for HTTPS connections through HTTP proxy (issue967)

urllib2 and httplib does not support using CONNECT proxy requests, but
only regular requests over the proxy. This does not work with HTTPS
requests as they typically require that the client issues a CONNECT to
the proxy to give a direct connection to the remote HTTPS server.

This is solved by duplicating some of the httplib functionality and
tying it together with the keepalive library such that a HTTPS
connection that need to be proxied can be proxied by letting a
connection be established to the proxy server and then subsequently
performing the normal request to the specified server through the
proxy server.

As it stands, the code also purports to support HTTPS proxies, i.e.
proxies that you connect to using SSL. These are extremely rare and
nothing is done to ensure that CONNECT requests can be made to these
as that would require multiple SSL handshakes. This use case is also
not supported by most other contemporary web tools like curl and
Firefox3.

mercurial/url.py

@@ -1,349 +1,496
 # 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, incorporated herein by reference.
 
-import urllib, urllib2, urlparse, httplib, os, re
+import urllib, urllib2, urlparse, httplib, os, re, socket, cStringIO
 from i18n import _
 import keepalive, util
 
 def hidepassword(url):
     '''hide user credential in a url string'''
     scheme, netloc, path, params, query, fragment = urlparse.urlparse(url)
     netloc = re.sub('([^:]*):([^@]*)@(.*)', r'\1:***@\3', netloc)
     return urlparse.urlunparse((scheme, netloc, path, params, query, fragment))
 
 def removeauth(url):
     '''remove all authentication information from a url string'''
     scheme, netloc, path, params, query, fragment = urlparse.urlparse(url)
     netloc = netloc[netloc.find('@')+1:]
     return urlparse.urlunparse((scheme, netloc, path, params, query, fragment))
 
 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
 
 _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 = set(_safe)
         _hex = 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 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:
             user, passwd = self._readauthtoken(authuri)
         if not user or not 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)
         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 _readauthtoken(self, uri):
         # Read configuration
         config = dict()
         for key, val in self.ui.configitems('auth'):
             group, setting = key.split('.', 1)
             gdict = config.setdefault(group, dict())
             gdict[setting] = val
 
         # Find the best match
         scheme, hostpath = uri.split('://', 1)
         bestlen = 0
         bestauth = None, None
         for auth in config.itervalues():
             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 and scheme in schemes:
                 bestlen = len(prefix)
                 bestauth = auth.get('username'), auth.get('password')
         return bestauth
 
 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 + '/'
             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 ui.configbool("http_proxy", "always"):
                 self.no_list = []
             else:
                 self.no_list = no_list
 
             proxyurl = urlparse.urlunsplit((
                 proxyscheme, netlocunsplit(proxyhost, proxyport,
                                                 proxyuser, proxypasswd or ''),
                 proxypath, proxyquery, proxyfrag))
             proxies = {'http': proxyurl, 'https': proxyurl}
             ui.debug(_('proxying through http://%s:%s\n') %
                       (proxyhost, proxyport))
         else:
             proxies = {}
 
         # 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 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]
         if host in self.no_list:
             return None
 
         # work around a bug in Python < 2.4.2
         # (it leaves a "\n" at the end of Proxy-authorization headers)
         baseclass = req.__class__
         class _request(baseclass):
             def add_header(self, key, val):
                 if key.lower() == 'proxy-authorization':
                     val = val.strip()
                 return baseclass.add_header(self, key, val)
         req.__class__ = _request
 
         return urllib2.ProxyHandler.proxy_open(self, req, proxy, type_)
 
 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
 
+has_https = hasattr(urllib2, 'HTTPSHandler')
+if has_https:
+    try:
+        # avoid using deprecated/broken FakeSocket in python 2.6
+        import ssl
+        _ssl_wrap_socket = ssl.wrap_socket
+    except ImportError:
+        def _ssl_wrap_socket(sock, key_file, cert_file):
+            ssl = socket.ssl(sock, key_file, cert_file)
+            return httplib.FakeSocket(sock, ssl)
+
 class httpconnection(keepalive.HTTPConnection):
     # must be able to send big bundle as stream.
     send = _gen_sendfile(keepalive.HTTPConnection)
 
+    def _proxytunnel(self):
+        proxyheaders = dict(
+                [(x, self.headers[x]) for x in self.headers
+                 if x.lower().startswith('proxy-')])
+        self._set_hostport(self.host, self.port)
+        self.send('CONNECT %s:%d HTTP/1.0\r\n' % (self.realhost, self.realport))
+        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, S4.4, #3 says we ignore this if tr_enc 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
+
+    def connect(self):
+        if has_https and self.realhost: # use CONNECT proxy
+            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.sock.connect((self.host, self.port))
+            if self._proxytunnel():
+                # we do not support client x509 certificates
+                self.sock = _ssl_wrap_socket(self.sock, None, None)
+        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)
+
 class httphandler(keepalive.HTTPHandler):
     def http_open(self, req):
         return self.do_open(httpconnection, req)
 
+    def _start_transaction(self, h, req):
+        if req.get_selector() == req.get_full_url(): # has proxy
+            urlparts = urlparse.urlparse(req.get_selector())
+            if urlparts[0] == 'https': # only use CONNECT for HTTPS
+                if ':' in urlparts[1]:
+                    realhost, realport = urlparts[1].split(':')
+                else:
+                    realhost = urlparts[1]
+                    realport = 443
+
+                h.realhost = realhost
+                h.realport = realport
+                h.headers = req.headers.copy()
+                h.headers.update(self.parent.addheaders)
+                return keepalive.HTTPHandler._start_transaction(self, h, req)
+
+        h.realhost = None
+        h.realport = None
+        h.headers = None
+        return keepalive.HTTPHandler._start_transaction(self, h, 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 httpshandler(keepalive.KeepAliveHandler, urllib2.HTTPSHandler):
         def https_open(self, req):
             return self.do_open(httpsconnection, req)
 
 # 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 getauthinfo(path):
     scheme, netloc, urlpath, query, frag = urlparse.urlsplit(path)
     if not urlpath:
         urlpath = '/'
     if scheme != 'file':
         # XXX: why are we quoting the path again with some smart
         # heuristic here? Anyway, it cannot be done with file://
         # urls since path encoding is os/fs dependent (see
         # urllib.pathname2url() for details).
         urlpath = quotepath(urlpath)
     host, port, user, passwd = netlocsplit(netloc)
 
     # urllib cannot handle URLs with embedded user or passwd
     url = urlparse.urlunsplit((scheme, netlocunsplit(host, port),
                               urlpath, query, frag))
     if user:
         netloc = host
         if port:
             netloc += ':' + port
         # Python < 2.4.3 uses only the netloc to search for a password
         authinfo = (None, (url, netloc), user, passwd or '')
     else:
         authinfo = None
     return url, authinfo
 
 def opener(ui, authinfo=None):
     '''
     construct an opener suitable for urllib2
     authinfo will be added to the password manager
     '''
     handlers = [httphandler()]
     if has_https:
         handlers.append(httpshandler())
 
     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((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')]
     opener.addheaders.append(('Accept', 'application/mercurial-0.1'))
     return opener
 
 scheme_re = re.compile(r'^([a-zA-Z0-9+-.]+)://')
 
 def open(ui, url, data=None):
     scheme = None
     m = scheme_re.search(url)
     if m:
         scheme = m.group(1).lower()
     if not scheme:
         path = util.normpath(os.path.abspath(url))
         url = 'file://' + urllib.pathname2url(path)
         authinfo = None
     else:
         url, authinfo = getauthinfo(url)
     return opener(ui, authinfo).open(url, data)