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diff --git a/mercurial/httpclient/__init__.py b/mercurial/httpclient/__init__.py
new file mode 100644
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+++ b/mercurial/httpclient/__init__.py
@@ -0,0 +1,674 @@
+# Copyright 2010, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""Improved HTTP/1.1 client library
+
+This library contains an HTTPConnection which is similar to the one in
+httplib, but has several additional features:
+
+  * supports keepalives natively
+  * uses select() to block for incoming data
+  * notices when the server responds early to a request
+  * implements ssl inline instead of in a different class
+"""
+
+import cStringIO
+import errno
+import httplib
+import logging
+import rfc822
+import select
+import socket
+
+import _readers
+import socketutil
+
+logger = logging.getLogger(__name__)
+
+__all__ = ['HTTPConnection', 'HTTPResponse']
+
+HTTP_VER_1_0 = 'HTTP/1.0'
+HTTP_VER_1_1 = 'HTTP/1.1'
+
+OUTGOING_BUFFER_SIZE = 1 << 15
+INCOMING_BUFFER_SIZE = 1 << 20
+
+HDR_ACCEPT_ENCODING = 'accept-encoding'
+HDR_CONNECTION_CTRL = 'connection'
+HDR_CONTENT_LENGTH = 'content-length'
+HDR_XFER_ENCODING = 'transfer-encoding'
+
+XFER_ENCODING_CHUNKED = 'chunked'
+
+CONNECTION_CLOSE = 'close'
+
+EOL = '\r\n'
+_END_HEADERS = EOL * 2
+
+# Based on some searching around, 1 second seems like a reasonable
+# default here.
+TIMEOUT_ASSUME_CONTINUE = 1
+TIMEOUT_DEFAULT = None
+
+
+class HTTPResponse(object):
+    """Response from an HTTP server.
+
+    The response will continue to load as available. If you need the
+    complete response before continuing, check the .complete() method.
+    """
+    def __init__(self, sock, timeout, method):
+        self.sock = sock
+        self.method = method
+        self.raw_response = ''
+        self._headers_len = 0
+        self.headers = None
+        self.will_close = False
+        self.status_line = ''
+        self.status = None
+        self.continued = False
+        self.http_version = None
+        self.reason = None
+        self._reader = None
+
+        self._read_location = 0
+        self._eol = EOL
+
+        self._timeout = timeout
+
+    @property
+    def _end_headers(self):
+        return self._eol * 2
+
+    def complete(self):
+        """Returns true if this response is completely loaded.
+
+        Note that if this is a connection where complete means the
+        socket is closed, this will nearly always return False, even
+        in cases where all the data has actually been loaded.
+        """
+        if self._reader:
+            return self._reader.done()
+
+    def _close(self):
+        if self._reader is not None:
+            self._reader._close()
+
+    def readline(self):
+        """Read a single line from the response body.
+
+        This may block until either a line ending is found or the
+        response is complete.
+        """
+        # TODO: move this into the reader interface where it can be
+        # smarter (and probably avoid copies)
+        bytes = []
+        while not bytes:
+            try:
+                bytes = [self._reader.read(1)]
+            except _readers.ReadNotReady:
+                self._select()
+        while bytes[-1] != '\n' and not self.complete():
+            self._select()
+            bytes.append(self._reader.read(1))
+        if bytes[-1] != '\n':
+            next = self._reader.read(1)
+            while next and next != '\n':
+                bytes.append(next)
+                next = self._reader.read(1)
+            bytes.append(next)
+        return ''.join(bytes)
+
+    def read(self, length=None):
+        # if length is None, unbounded read
+        while (not self.complete()  # never select on a finished read
+               and (not length  # unbounded, so we wait for complete()
+                    or length > self._reader.available_data)):
+            self._select()
+        if not length:
+            length = self._reader.available_data
+        r = self._reader.read(length)
+        if self.complete() and self.will_close:
+            self.sock.close()
+        return r
+
+    def _select(self):
+        r, _, _ = select.select([self.sock], [], [], self._timeout)
+        if not r:
+            # socket was not readable. If the response is not
+            # complete, raise a timeout.
+            if not self.complete():
+                logger.info('timed out with timeout of %s', self._timeout)
+                raise HTTPTimeoutException('timeout reading data')
+        try:
+            data = self.sock.recv(INCOMING_BUFFER_SIZE)
+        except socket.sslerror, e:
+            if e.args[0] != socket.SSL_ERROR_WANT_READ:
+                raise
+            logger.debug('SSL_WANT_READ in _select, should retry later')
+            return True
+        logger.debug('response read %d data during _select', len(data))
+        # If the socket was readable and no data was read, that means
+        # the socket was closed. Inform the reader (if any) so it can
+        # raise an exception if this is an invalid situation.
+        if not data:
+            if self._reader:
+                self._reader._close()
+            return False
+        else:
+            self._load_response(data)
+            return True
+
+    def _load_response(self, data):
+        # Being here implies we're not at the end of the headers yet,
+        # since at the end of this method if headers were completely
+        # loaded we replace this method with the load() method of the
+        # reader we created.
+        self.raw_response += data
+        # This is a bogus server with bad line endings
+        if self._eol not in self.raw_response:
+            for bad_eol in ('\n', '\r'):
+                if (bad_eol in self.raw_response
+                    # verify that bad_eol is not the end of the incoming data
+                    # as this could be a response line that just got
+                    # split between \r and \n.
+                    and (self.raw_response.index(bad_eol) <
+                         (len(self.raw_response) - 1))):
+                    logger.info('bogus line endings detected, '
+                                'using %r for EOL', bad_eol)
+                    self._eol = bad_eol
+                    break
+        # exit early if not at end of headers
+        if self._end_headers not in self.raw_response or self.headers:
+            return
+
+        # handle 100-continue response
+        hdrs, body = self.raw_response.split(self._end_headers, 1)
+        http_ver, status = hdrs.split(' ', 1)
+        if status.startswith('100'):
+            self.raw_response = body
+            self.continued = True
+            logger.debug('continue seen, setting body to %r', body)
+            return
+
+        # arriving here means we should parse response headers
+        # as all headers have arrived completely
+        hdrs, body = self.raw_response.split(self._end_headers, 1)
+        del self.raw_response
+        if self._eol in hdrs:
+            self.status_line, hdrs = hdrs.split(self._eol, 1)
+        else:
+            self.status_line = hdrs
+            hdrs = ''
+        # TODO HTTP < 1.0 support
+        (self.http_version, self.status,
+         self.reason) = self.status_line.split(' ', 2)
+        self.status = int(self.status)
+        if self._eol != EOL:
+            hdrs = hdrs.replace(self._eol, '\r\n')
+        headers = rfc822.Message(cStringIO.StringIO(hdrs))
+        content_len = None
+        if HDR_CONTENT_LENGTH in headers:
+            content_len = int(headers[HDR_CONTENT_LENGTH])
+        if self.http_version == HTTP_VER_1_0:
+            self.will_close = True
+        elif HDR_CONNECTION_CTRL in headers:
+            self.will_close = (
+                headers[HDR_CONNECTION_CTRL].lower() == CONNECTION_CLOSE)
+        if (HDR_XFER_ENCODING in headers
+            and headers[HDR_XFER_ENCODING].lower() == XFER_ENCODING_CHUNKED):
+            self._reader = _readers.ChunkedReader(self._eol)
+            logger.debug('using a chunked reader')
+        else:
+            # HEAD responses are forbidden from returning a body, and
+            # it's implausible for a CONNECT response to use
+            # close-is-end logic for an OK response.
+            if (self.method == 'HEAD' or
+                (self.method == 'CONNECT' and content_len is None)):
+                content_len = 0
+            if content_len is not None:
+                logger.debug('using a content-length reader with length %d',
+                             content_len)
+                self._reader = _readers.ContentLengthReader(content_len)
+            else:
+                # Response body had no length specified and is not
+                # chunked, so the end of the body will only be
+                # identifiable by the termination of the socket by the
+                # server. My interpretation of the spec means that we
+                # are correct in hitting this case if
+                # transfer-encoding, content-length, and
+                # connection-control were left unspecified.
+                self._reader = _readers.CloseIsEndReader()
+                logger.debug('using a close-is-end reader')
+                self.will_close = True
+
+        if body:
+            self._reader._load(body)
+        logger.debug('headers complete')
+        self.headers = headers
+        self._load_response = self._reader._load
+
+
+class HTTPConnection(object):
+    """Connection to a single http server.
+
+    Supports 100-continue and keepalives natively. Uses select() for
+    non-blocking socket operations.
+    """
+    http_version = HTTP_VER_1_1
+    response_class = HTTPResponse
+
+    def __init__(self, host, port=None, use_ssl=None, ssl_validator=None,
+                 timeout=TIMEOUT_DEFAULT,
+                 continue_timeout=TIMEOUT_ASSUME_CONTINUE,
+                 proxy_hostport=None, **ssl_opts):
+        """Create a new HTTPConnection.
+
+        Args:
+          host: The host to which we'll connect.
+          port: Optional. The port over which we'll connect. Default 80 for
+                non-ssl, 443 for ssl.
+          use_ssl: Optional. Wether to use ssl. Defaults to False if port is
+                   not 443, true if port is 443.
+          ssl_validator: a function(socket) to validate the ssl cert
+          timeout: Optional. Connection timeout, default is TIMEOUT_DEFAULT.
+          continue_timeout: Optional. Timeout for waiting on an expected
+                   "100 Continue" response. Default is TIMEOUT_ASSUME_CONTINUE.
+          proxy_hostport: Optional. Tuple of (host, port) to use as an http
+                       proxy for the connection. Default is to not use a proxy.
+        """
+        if port is None and host.count(':') == 1 or ']:' in host:
+            host, port = host.rsplit(':', 1)
+            port = int(port)
+            if '[' in host:
+                host = host[1:-1]
+        if use_ssl is None and port is None:
+            use_ssl = False
+            port = 80
+        elif use_ssl is None:
+            use_ssl = (port == 443)
+        elif port is None:
+            port = (use_ssl and 443 or 80)
+        self.port = port
+        if use_ssl and not socketutil.have_ssl:
+            raise Exception('ssl requested but unavailable on this Python')
+        self.ssl = use_ssl
+        self.ssl_opts = ssl_opts
+        self._ssl_validator = ssl_validator
+        self.host = host
+        self.sock = None
+        self._current_response = None
+        self._current_response_taken = False
+        if proxy_hostport is None:
+            self._proxy_host = self._proxy_port = None
+        else:
+            self._proxy_host, self._proxy_port = proxy_hostport
+
+        self.timeout = timeout
+        self.continue_timeout = continue_timeout
+
+    def _connect(self):
+        """Connect to the host and port specified in __init__."""
+        if self.sock:
+            return
+        if self._proxy_host is not None:
+            logger.info('Connecting to http proxy %s:%s',
+                        self._proxy_host, self._proxy_port)
+            sock = socketutil.create_connection((self._proxy_host,
+                                                 self._proxy_port))
+            if self.ssl:
+                # TODO proxy header support
+                data = self.buildheaders('CONNECT', '%s:%d' % (self.host,
+                                                               self.port),
+                                         {}, HTTP_VER_1_0)
+                sock.send(data)
+                sock.setblocking(0)
+                r = self.response_class(sock, self.timeout, 'CONNECT')
+                timeout_exc = HTTPTimeoutException(
+                    'Timed out waiting for CONNECT response from proxy')
+                while not r.complete():
+                    try:
+                        if not r._select():
+                            if not r.complete():
+                                raise timeout_exc
+                    except HTTPTimeoutException:
+                        # This raise/except pattern looks goofy, but
+                        # _select can raise the timeout as well as the
+                        # loop body. I wish it wasn't this convoluted,
+                        # but I don't have a better solution
+                        # immediately handy.
+                        raise timeout_exc
+                if r.status != 200:
+                    raise HTTPProxyConnectFailedException(
+                        'Proxy connection failed: %d %s' % (r.status,
+                                                            r.read()))
+                logger.info('CONNECT (for SSL) to %s:%s via proxy succeeded.',
+                            self.host, self.port)
+        else:
+            sock = socketutil.create_connection((self.host, self.port))
+        if self.ssl:
+            # This is the default, but in the case of proxied SSL
+            # requests the proxy logic above will have cleared
+            # blocking mode, so reenable it just to be safe.
+            sock.setblocking(1)
+            logger.debug('wrapping socket for ssl with options %r',
+                         self.ssl_opts)
+            sock = socketutil.wrap_socket(sock, **self.ssl_opts)
+            if self._ssl_validator:
+                self._ssl_validator(sock)
+        sock.setblocking(0)
+        self.sock = sock
+
+    def buildheaders(self, method, path, headers, http_ver):
+        if self.ssl and self.port == 443 or self.port == 80:
+            # default port for protocol, so leave it out
+            hdrhost = self.host
+        else:
+            # include nonstandard port in header
+            if ':' in self.host:  # must be IPv6
+                hdrhost = '[%s]:%d' % (self.host, self.port)
+            else:
+                hdrhost = '%s:%d' % (self.host, self.port)
+        if self._proxy_host and not self.ssl:
+            # When talking to a regular http proxy we must send the
+            # full URI, but in all other cases we must not (although
+            # technically RFC 2616 says servers must accept our
+            # request if we screw up, experimentally few do that
+            # correctly.)
+            assert path[0] == '/', 'path must start with a /'
+            path = 'http://%s%s' % (hdrhost, path)
+        outgoing = ['%s %s %s%s' % (method, path, http_ver, EOL)]
+        headers['host'] = ('Host', hdrhost)
+        headers[HDR_ACCEPT_ENCODING] = (HDR_ACCEPT_ENCODING, 'identity')
+        for hdr, val in headers.itervalues():
+            outgoing.append('%s: %s%s' % (hdr, val, EOL))
+        outgoing.append(EOL)
+        return ''.join(outgoing)
+
+    def close(self):
+        """Close the connection to the server.
+
+        This is a no-op if the connection is already closed. The
+        connection may automatically close if requessted by the server
+        or required by the nature of a response.
+        """
+        if self.sock is None:
+            return
+        self.sock.close()
+        self.sock = None
+        logger.info('closed connection to %s on %s', self.host, self.port)
+
+    def busy(self):
+        """Returns True if this connection object is currently in use.
+
+        If a response is still pending, this will return True, even if
+        the request has finished sending. In the future,
+        HTTPConnection may transparently juggle multiple connections
+        to the server, in which case this will be useful to detect if
+        any of those connections is ready for use.
+        """
+        cr = self._current_response
+        if cr is not None:
+            if self._current_response_taken:
+                if cr.will_close:
+                    self.sock = None
+                    self._current_response = None
+                    return False
+                elif cr.complete():
+                    self._current_response = None
+                    return False
+            return True
+        return False
+
+    def request(self, method, path, body=None, headers={},
+                expect_continue=False):
+        """Send a request to the server.
+
+        For increased flexibility, this does not return the response
+        object. Future versions of HTTPConnection that juggle multiple
+        sockets will be able to send (for example) 5 requests all at
+        once, and then let the requests arrive as data is
+        available. Use the `getresponse()` method to retrieve the
+        response.
+        """
+        if self.busy():
+            raise httplib.CannotSendRequest(
+                'Can not send another request before '
+                'current response is read!')
+        self._current_response_taken = False
+
+        logger.info('sending %s request for %s to %s on port %s',
+                    method, path, self.host, self.port)
+        hdrs = dict((k.lower(), (k, v)) for k, v in headers.iteritems())
+        if hdrs.get('expect', ('', ''))[1].lower() == '100-continue':
+            expect_continue = True
+        elif expect_continue:
+            hdrs['expect'] = ('Expect', '100-Continue')
+
+        chunked = False
+        if body and HDR_CONTENT_LENGTH not in hdrs:
+            if getattr(body, '__len__', False):
+                hdrs[HDR_CONTENT_LENGTH] = (HDR_CONTENT_LENGTH, len(body))
+            elif getattr(body, 'read', False):
+                hdrs[HDR_XFER_ENCODING] = (HDR_XFER_ENCODING,
+                                           XFER_ENCODING_CHUNKED)
+                chunked = True
+            else:
+                raise BadRequestData('body has no __len__() nor read()')
+
+        self._connect()
+        outgoing_headers = self.buildheaders(
+            method, path, hdrs, self.http_version)
+        response = None
+        first = True
+
+        def reconnect(where):
+            logger.info('reconnecting during %s', where)
+            self.close()
+            self._connect()
+
+        while ((outgoing_headers or body)
+               and not (response and response.complete())):
+            select_timeout = self.timeout
+            out = outgoing_headers or body
+            blocking_on_continue = False
+            if expect_continue and not outgoing_headers and not (
+                response and (response.headers or response.continued)):
+                logger.info(
+                    'waiting up to %s seconds for'
+                    ' continue response from server',
+                    self.continue_timeout)
+                select_timeout = self.continue_timeout
+                blocking_on_continue = True
+                out = False
+            if out:
+                w = [self.sock]
+            else:
+                w = []
+            r, w, x = select.select([self.sock], w, [], select_timeout)
+            # if we were expecting a 100 continue and it's been long
+            # enough, just go ahead and assume it's ok. This is the
+            # recommended behavior from the RFC.
+            if r == w == x == []:
+                if blocking_on_continue:
+                    expect_continue = False
+                    logger.info('no response to continue expectation from '
+                                'server, optimistically sending request body')
+                else:
+                    raise HTTPTimeoutException('timeout sending data')
+            was_first = first
+
+            # incoming data
+            if r:
+                try:
+                    try:
+                        data = r[0].recv(INCOMING_BUFFER_SIZE)
+                    except socket.sslerror, e:
+                        if e.args[0] != socket.SSL_ERROR_WANT_READ:
+                            raise
+                        logger.debug(
+                            'SSL_WANT_READ while sending data, retrying...')
+                        continue
+                    if not data:
+                        logger.info('socket appears closed in read')
+                        self.sock = None
+                        self._current_response = None
+                        if response is not None:
+                            response._close()
+                        # This if/elif ladder is a bit subtle,
+                        # comments in each branch should help.
+                        if response is not None and response.complete():
+                            # Server responded completely and then
+                            # closed the socket. We should just shut
+                            # things down and let the caller get their
+                            # response.
+                            logger.info('Got an early response, '
+                                        'aborting remaining request.')
+                            break
+                        elif was_first and response is None:
+                            # Most likely a keepalive that got killed
+                            # on the server's end. Commonly happens
+                            # after getting a really large response
+                            # from the server.
+                            logger.info(
+                                'Connection appeared closed in read on first'
+                                ' request loop iteration, will retry.')
+                            reconnect('read')
+                            continue
+                        else:
+                            # We didn't just send the first data hunk,
+                            # and either have a partial response or no
+                            # response at all. There's really nothing
+                            # meaningful we can do here.
+                            raise HTTPStateError(
+                                'Connection appears closed after '
+                                'some request data was written, but the '
+                                'response was missing or incomplete!')
+                    logger.debug('read %d bytes in request()', len(data))
+                    if response is None:
+                        response = self.response_class(r[0], self.timeout, method)
+                    response._load_response(data)
+                    # Jump to the next select() call so we load more
+                    # data if the server is still sending us content.
+                    continue
+                except socket.error, e:
+                    if e[0] != errno.EPIPE and not was_first:
+                        raise
+
+            # outgoing data
+            if w and out:
+                try:
+                    if getattr(out, 'read', False):
+                        data = out.read(OUTGOING_BUFFER_SIZE)
+                        if not data:
+                            continue
+                        if len(data) < OUTGOING_BUFFER_SIZE:
+                            if chunked:
+                                body = '0' + EOL + EOL
+                            else:
+                                body = None
+                        if chunked:
+                            out = hex(len(data))[2:] + EOL + data + EOL
+                        else:
+                            out = data
+                    amt = w[0].send(out)
+                except socket.error, e:
+                    if e[0] == socket.SSL_ERROR_WANT_WRITE and self.ssl:
+                        # This means that SSL hasn't flushed its buffer into
+                        # the socket yet.
+                        # TODO: find a way to block on ssl flushing its buffer
+                        # similar to selecting on a raw socket.
+                        continue
+                    elif (e[0] not in (errno.ECONNRESET, errno.EPIPE)
+                          and not first):
+                        raise
+                    reconnect('write')
+                    amt = self.sock.send(out)
+                logger.debug('sent %d', amt)
+                first = False
+                # stash data we think we sent in case the socket breaks
+                # when we read from it
+                if was_first:
+                    sent_data = out[:amt]
+                if out is body:
+                    body = out[amt:]
+                else:
+                    outgoing_headers = out[amt:]
+
+        # close if the server response said to or responded before eating
+        # the whole request
+        if response is None:
+            response = self.response_class(self.sock, self.timeout, method)
+        complete = response.complete()
+        data_left = bool(outgoing_headers or body)
+        if data_left:
+            logger.info('stopped sending request early, '
+                         'will close the socket to be safe.')
+            response.will_close = True
+        if response.will_close:
+            # The socket will be closed by the response, so we disown
+            # the socket
+            self.sock = None
+        self._current_response = response
+
+    def getresponse(self):
+        if self._current_response is None:
+            raise httplib.ResponseNotReady()
+        r = self._current_response
+        while r.headers is None:
+            if not r._select() and not r.complete():
+                raise _readers.HTTPRemoteClosedError()
+        if r.will_close:
+            self.sock = None
+            self._current_response = None
+        elif r.complete():
+            self._current_response = None
+        else:
+            self._current_response_taken = True
+        return r
+
+
+class HTTPTimeoutException(httplib.HTTPException):
+    """A timeout occurred while waiting on the server."""
+
+
+class BadRequestData(httplib.HTTPException):
+    """Request body object has neither __len__ nor read."""
+
+
+class HTTPProxyConnectFailedException(httplib.HTTPException):
+    """Connecting to the HTTP proxy failed."""
+
+
+class HTTPStateError(httplib.HTTPException):
+    """Invalid internal state encountered."""
+
+# Forward this exception type from _readers since it needs to be part
+# of the public API.
+HTTPRemoteClosedError = _readers.HTTPRemoteClosedError
+# no-check-code
diff --git a/mercurial/httpclient/_readers.py b/mercurial/httpclient/_readers.py
new file mode 100644
index 0000000..0beb551
--- /dev/null
+++ b/mercurial/httpclient/_readers.py
@@ -0,0 +1,195 @@
+# Copyright 2011, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""Reader objects to abstract out different body response types.
+
+This module is package-private. It is not expected that these will
+have any clients outside of httpplus.
+"""
+
+import httplib
+import itertools
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class ReadNotReady(Exception):
+    """Raised when read() is attempted but not enough data is loaded."""
+
+
+class HTTPRemoteClosedError(httplib.HTTPException):
+    """The server closed the remote socket in the middle of a response."""
+
+
+class AbstractReader(object):
+    """Abstract base class for response readers.
+
+    Subclasses must implement _load, and should implement _close if
+    it's not an error for the server to close their socket without
+    some termination condition being detected during _load.
+    """
+    def __init__(self):
+        self._finished = False
+        self._done_chunks = []
+
+    @property
+    def available_data(self):
+        return sum(map(len, self._done_chunks))
+
+    def done(self):
+        return self._finished
+
+    def read(self, amt):
+        if self.available_data < amt and not self._finished:
+            raise ReadNotReady()
+        need = [amt]
+        def pred(s):
+            needed = need[0] > 0
+            need[0] -= len(s)
+            return needed
+        blocks = list(itertools.takewhile(pred, self._done_chunks))
+        self._done_chunks = self._done_chunks[len(blocks):]
+        over_read = sum(map(len, blocks)) - amt
+        if over_read > 0 and blocks:
+            logger.debug('need to reinsert %d data into done chunks', over_read)
+            last = blocks[-1]
+            blocks[-1], reinsert = last[:-over_read], last[-over_read:]
+            self._done_chunks.insert(0, reinsert)
+        result = ''.join(blocks)
+        assert len(result) == amt or (self._finished and len(result) < amt)
+        return result
+
+    def _load(self, data): # pragma: no cover
+        """Subclasses must implement this.
+
+        As data is available to be read out of this object, it should
+        be placed into the _done_chunks list. Subclasses should not
+        rely on data remaining in _done_chunks forever, as it may be
+        reaped if the client is parsing data as it comes in.
+        """
+        raise NotImplementedError
+
+    def _close(self):
+        """Default implementation of close.
+
+        The default implementation assumes that the reader will mark
+        the response as finished on the _finished attribute once the
+        entire response body has been read. In the event that this is
+        not true, the subclass should override the implementation of
+        close (for example, close-is-end responses have to set
+        self._finished in the close handler.)
+        """
+        if not self._finished:
+            raise HTTPRemoteClosedError(
+                'server appears to have closed the socket mid-response')
+
+
+class AbstractSimpleReader(AbstractReader):
+    """Abstract base class for simple readers that require no response decoding.
+
+    Examples of such responses are Connection: Close (close-is-end)
+    and responses that specify a content length.
+    """
+    def _load(self, data):
+        if data:
+            assert not self._finished, (
+                'tried to add data (%r) to a closed reader!' % data)
+        logger.debug('%s read an addtional %d data', self.name, len(data))
+        self._done_chunks.append(data)
+
+
+class CloseIsEndReader(AbstractSimpleReader):
+    """Reader for responses that specify Connection: Close for length."""
+    name = 'close-is-end'
+
+    def _close(self):
+        logger.info('Marking close-is-end reader as closed.')
+        self._finished = True
+
+
+class ContentLengthReader(AbstractSimpleReader):
+    """Reader for responses that specify an exact content length."""
+    name = 'content-length'
+
+    def __init__(self, amount):
+        AbstractReader.__init__(self)
+        self._amount = amount
+        if amount == 0:
+            self._finished = True
+        self._amount_seen = 0
+
+    def _load(self, data):
+        AbstractSimpleReader._load(self, data)
+        self._amount_seen += len(data)
+        if self._amount_seen >= self._amount:
+            self._finished = True
+            logger.debug('content-length read complete')
+
+
+class ChunkedReader(AbstractReader):
+    """Reader for chunked transfer encoding responses."""
+    def __init__(self, eol):
+        AbstractReader.__init__(self)
+        self._eol = eol
+        self._leftover_skip_amt = 0
+        self._leftover_data = ''
+
+    def _load(self, data):
+        assert not self._finished, 'tried to add data to a closed reader!'
+        logger.debug('chunked read an addtional %d data', len(data))
+        position = 0
+        if self._leftover_data:
+            logger.debug('chunked reader trying to finish block from leftover data')
+            # TODO: avoid this string concatenation if possible
+            data = self._leftover_data + data
+            position = self._leftover_skip_amt
+            self._leftover_data = ''
+            self._leftover_skip_amt = 0
+        datalen = len(data)
+        while position < datalen:
+            split = data.find(self._eol, position)
+            if split == -1:
+                self._leftover_data = data
+                self._leftover_skip_amt = position
+                return
+            amt = int(data[position:split], base=16)
+            block_start = split + len(self._eol)
+            # If the whole data chunk plus the eol trailer hasn't
+            # loaded, we'll wait for the next load.
+            if block_start + amt + len(self._eol) > len(data):
+                self._leftover_data = data
+                self._leftover_skip_amt = position
+                return
+            if amt == 0:
+                self._finished = True
+                logger.debug('closing chunked redaer due to chunk of length 0')
+                return
+            self._done_chunks.append(data[block_start:block_start + amt])
+            position = block_start + amt + len(self._eol)
+# no-check-code
diff --git a/mercurial/httpclient/socketutil.py b/mercurial/httpclient/socketutil.py
new file mode 100644
index 0000000..6f06a3c
--- /dev/null
+++ b/mercurial/httpclient/socketutil.py
@@ -0,0 +1,127 @@
+# Copyright 2010, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""Abstraction to simplify socket use for Python < 2.6
+
+This will attempt to use the ssl module and the new
+socket.create_connection method, but fall back to the old
+methods if those are unavailable.
+"""
+import logging
+import socket
+
+logger = logging.getLogger(__name__)
+
+try:
+    import ssl
+    ssl.wrap_socket  # make demandimporters load the module
+    have_ssl = True
+except ImportError:
+    import httplib
+    import urllib2
+    have_ssl = getattr(urllib2, 'HTTPSHandler', False)
+    ssl = False
+
+
+try:
+    create_connection = socket.create_connection
+except AttributeError:
+    def create_connection(address):
+        host, port = address
+        msg = "getaddrinfo returns an empty list"
+        sock = None
+        for res in socket.getaddrinfo(host, port, 0,
+                                      socket.SOCK_STREAM):
+            af, socktype, proto, _canonname, sa = res
+            try:
+                sock = socket.socket(af, socktype, proto)
+                logger.info("connect: (%s, %s)", host, port)
+                sock.connect(sa)
+            except socket.error, msg:
+                logger.info('connect fail: %s %s', host, port)
+                if sock:
+                    sock.close()
+                sock = None
+                continue
+            break
+        if not sock:
+            raise socket.error, msg
+        return sock
+
+if ssl:
+    wrap_socket = ssl.wrap_socket
+    CERT_NONE = ssl.CERT_NONE
+    CERT_OPTIONAL = ssl.CERT_OPTIONAL
+    CERT_REQUIRED = ssl.CERT_REQUIRED
+else:
+    class FakeSocket(httplib.FakeSocket):
+        """Socket wrapper that supports SSL.
+        """
+        # backport the behavior from Python 2.6, which is to busy wait
+        # on the socket instead of anything nice. Sigh.
+        # See http://bugs.python.org/issue3890 for more info.
+        def recv(self, buflen=1024, flags=0):
+            """ssl-aware wrapper around socket.recv
+            """
+            if flags != 0:
+                raise ValueError(
+                    "non-zero flags not allowed in calls to recv() on %s" %
+                    self.__class__)
+            while True:
+                try:
+                    return self._ssl.read(buflen)
+                except socket.sslerror, x:
+                    if x.args[0] == socket.SSL_ERROR_WANT_READ:
+                        continue
+                    else:
+                        raise x
+
+    _PROTOCOL_SSLv23 = 2
+
+    CERT_NONE = 0
+    CERT_OPTIONAL = 1
+    CERT_REQUIRED = 2
+
+    def wrap_socket(sock, keyfile=None, certfile=None,
+                server_side=False, cert_reqs=CERT_NONE,
+                ssl_version=_PROTOCOL_SSLv23, ca_certs=None,
+                do_handshake_on_connect=True,
+                suppress_ragged_eofs=True):
+        if cert_reqs != CERT_NONE and ca_certs:
+            raise CertificateValidationUnsupported(
+                'SSL certificate validation requires the ssl module'
+                '(included in Python 2.6 and later.)')
+        sslob = socket.ssl(sock)
+        # borrow httplib's workaround for no ssl.wrap_socket
+        sock = FakeSocket(sock, sslob)
+        return sock
+
+
+class CertificateValidationUnsupported(Exception):
+    """Exception raised when cert validation is requested but unavailable."""
+# no-check-code