# urllib3/connectionpool.py
# Copyright 2008-2013 Andrey Petrov and contributors (see CONTRIBUTORS.txt)
#
# This module is part of urllib3 and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
import sys
import errno
import logging
from socket import error as SocketError, timeout as SocketTimeout
import socket
try: # Python 3
from queue import LifoQueue, Empty, Full
except ImportError:
from Queue import LifoQueue, Empty, Full
import Queue as _ # Platform-specific: Windows
from .exceptions import (
ClosedPoolError,
ConnectionError,
ConnectTimeoutError,
EmptyPoolError,
HostChangedError,
LocationParseError,
MaxRetryError,
SSLError,
TimeoutError,
ReadTimeoutError,
ProxyError,
)
from .packages.ssl_match_hostname import CertificateError
from .packages import six
from .connection import (
port_by_scheme,
DummyConnection,
HTTPConnection, HTTPSConnection, VerifiedHTTPSConnection,
HTTPException, BaseSSLError,
)
from .request import RequestMethods
from .response import HTTPResponse
from .util import (
get_host,
is_connection_dropped,
Timeout,
)
xrange = six.moves.xrange
log = logging.getLogger(__name__)
_Default = object()
## Pool objects
class ConnectionPool(object):
"""
Base class for all connection pools, such as
:class:`.HTTPConnectionPool` and :class:`.HTTPSConnectionPool`.
"""
scheme = None
QueueCls = LifoQueue
def __init__(self, host, port=None):
if host is None:
raise LocationParseError(host)
# httplib doesn't like it when we include brackets in ipv6 addresses
host = host.strip('[]')
self.host = host
self.port = port
def __str__(self):
return '%s(host=%r, port=%r)' % (type(self).__name__,
self.host, self.port)
# This is taken from http://hg.python.org/cpython/file/7aaba721ebc0/Lib/socket.py#l252
_blocking_errnos = set([errno.EAGAIN, errno.EWOULDBLOCK])
class HTTPConnectionPool(ConnectionPool, RequestMethods):
"""
Thread-safe connection pool for one host.
:param host:
Host used for this HTTP Connection (e.g. "localhost"), passed into
:class:`httplib.HTTPConnection`.
:param port:
Port used for this HTTP Connection (None is equivalent to 80), passed
into :class:`httplib.HTTPConnection`.
:param strict:
Causes BadStatusLine to be raised if the status line can't be parsed
as a valid HTTP/1.0 or 1.1 status line, passed into
:class:`httplib.HTTPConnection`.
.. note::
Only works in Python 2. This parameter is ignored in Python 3.
:param timeout:
Socket timeout in seconds for each individual connection. This can
be a float or integer, which sets the timeout for the HTTP request,
or an instance of :class:`urllib3.util.Timeout` which gives you more
fine-grained control over request timeouts. After the constructor has
been parsed, this is always a `urllib3.util.Timeout` object.
:param maxsize:
Number of connections to save that can be reused. More than 1 is useful
in multithreaded situations. If ``block`` is set to false, more
connections will be created but they will not be saved once they've
been used.
:param block:
If set to True, no more than ``maxsize`` connections will be used at
a time. When no free connections are available, the call will block
until a connection has been released. This is a useful side effect for
particular multithreaded situations where one does not want to use more
than maxsize connections per host to prevent flooding.
:param headers:
Headers to include with all requests, unless other headers are given
explicitly.
:param _proxy:
Parsed proxy URL, should not be used directly, instead, see
:class:`urllib3.connectionpool.ProxyManager`"
:param _proxy_headers:
A dictionary with proxy headers, should not be used directly,
instead, see :class:`urllib3.connectionpool.ProxyManager`"
"""
scheme = 'http'
ConnectionCls = HTTPConnection
def __init__(self, host, port=None, strict=False,
timeout=Timeout.DEFAULT_TIMEOUT, maxsize=1, block=False,
headers=None, _proxy=None, _proxy_headers=None, **conn_kw):
ConnectionPool.__init__(self, host, port)
RequestMethods.__init__(self, headers)
self.strict = strict
# This is for backwards compatibility and can be removed once a timeout
# can only be set to a Timeout object
if not isinstance(timeout, Timeout):
timeout = Timeout.from_float(timeout)
self.timeout = timeout
self.pool = self.QueueCls(maxsize)
self.block = block
self.proxy = _proxy
self.proxy_headers = _proxy_headers or {}
# Fill the queue up so that doing get() on it will block properly
for _ in xrange(maxsize):
self.pool.put(None)
# These are mostly for testing and debugging purposes.
self.num_connections = 0
self.num_requests = 0
if sys.version_info < (2, 7): # Python 2.6 and older
conn_kw.pop('source_address', None)
self.conn_kw = conn_kw
def _new_conn(self):
"""
Return a fresh :class:`HTTPConnection`.
"""
self.num_connections += 1
log.info("Starting new HTTP connection (%d): %s" %
(self.num_connections, self.host))
conn = self.ConnectionCls(host=self.host, port=self.port,
timeout=self.timeout.connect_timeout,
strict=self.strict, **self.conn_kw)
if self.proxy is not None:
# Enable Nagle's algorithm for proxies, to avoid packet
# fragmentation.
conn.tcp_nodelay = 0
return conn
def _get_conn(self, timeout=None):
"""
Get a connection. Will return a pooled connection if one is available.
If no connections are available and :prop:`.block` is ``False``, then a
fresh connection is returned.
:param timeout:
Seconds to wait before giving up and raising
:class:`urllib3.exceptions.EmptyPoolError` if the pool is empty and
:prop:`.block` is ``True``.
"""
conn = None
try:
conn = self.pool.get(block=self.block, timeout=timeout)
except AttributeError: # self.pool is None
raise ClosedPoolError(self, "Pool is closed.")
except Empty:
if self.block:
raise EmptyPoolError(self,
"Pool reached maximum size and no more "
"connections are allowed.")
pass # Oh well, we'll create a new connection then
# If this is a persistent connection, check if it got disconnected
if conn and is_connection_dropped(conn):
log.info("Resetting dropped connection: %s" % self.host)
conn.close()
return conn or self._new_conn()
def _put_conn(self, conn):
"""
Put a connection back into the pool.
:param conn:
Connection object for the current host and port as returned by
:meth:`._new_conn` or :meth:`._get_conn`.
If the pool is already full, the connection is closed and discarded
because we exceeded maxsize. If connections are discarded frequently,
then maxsize should be increased.
If the pool is closed, then the connection will be closed and discarded.
"""
try:
self.pool.put(conn, block=False)
return # Everything is dandy, done.
except AttributeError:
# self.pool is None.
pass
except Full:
# This should never happen if self.block == True
log.warning(
"Connection pool is full, discarding connection: %s" %
self.host)
# Connection never got put back into the pool, close it.
if conn:
conn.close()
def _get_timeout(self, timeout):
""" Helper that always returns a :class:`urllib3.util.Timeout` """
if timeout is _Default:
return self.timeout.clone()
if isinstance(timeout, Timeout):
return timeout.clone()
else:
# User passed us an int/float. This is for backwards compatibility,
# can be removed later
return Timeout.from_float(timeout)
def _make_request(self, conn, method, url, timeout=_Default,
**httplib_request_kw):
"""
Perform a request on a given urllib connection object taken from our
pool.
:param conn:
a connection from one of our connection pools
:param timeout:
Socket timeout in seconds for the request. This can be a
float or integer, which will set the same timeout value for
the socket connect and the socket read, or an instance of
:class:`urllib3.util.Timeout`, which gives you more fine-grained
control over your timeouts.
"""
self.num_requests += 1
timeout_obj = self._get_timeout(timeout)
try:
timeout_obj.start_connect()
conn.timeout = timeout_obj.connect_timeout
# conn.request() calls httplib.*.request, not the method in
# urllib3.request. It also calls makefile (recv) on the socket.
conn.request(method, url, **httplib_request_kw)
except SocketTimeout:
raise ConnectTimeoutError(
self, "Connection to %s timed out. (connect timeout=%s)" %
(self.host, timeout_obj.connect_timeout))
# Reset the timeout for the recv() on the socket
read_timeout = timeout_obj.read_timeout
# App Engine doesn't have a sock attr
if hasattr(conn, 'sock'):
# In Python 3 socket.py will catch EAGAIN and return None when you
# try and read into the file pointer created by http.client, which
# instead raises a BadStatusLine exception. Instead of catching
# the exception and assuming all BadStatusLine exceptions are read
# timeouts, check for a zero timeout before making the request.
if read_timeout == 0:
raise ReadTimeoutError(
self, url,
"Read timed out. (read timeout=%s)" % read_timeout)
if read_timeout is Timeout.DEFAULT_TIMEOUT:
conn.sock.settimeout(socket.getdefaulttimeout())
else: # None or a value
conn.sock.settimeout(read_timeout)
# Receive the response from the server
try:
try: # Python 2.7+, use buffering of HTTP responses
httplib_response = conn.getresponse(buffering=True)
except TypeError: # Python 2.6 and older
httplib_response = conn.getresponse()
except SocketTimeout:
raise ReadTimeoutError(
self, url, "Read timed out. (read timeout=%s)" % read_timeout)
except BaseSSLError as e:
# Catch possible read timeouts thrown as SSL errors. If not the
# case, rethrow the original. We need to do this because of:
# http://bugs.python.org/issue10272
if 'timed out' in str(e) or \
'did not complete (read)' in str(e): # Python 2.6
raise ReadTimeoutError(self, url, "Read timed out.")
raise
except SocketError as e: # Platform-specific: Python 2
# See the above comment about EAGAIN in Python 3. In Python 2 we
# have to specifically catch it and throw the timeout error
if e.errno in _blocking_errnos:
raise ReadTimeoutError(
self, url,
"Read timed out. (read timeout=%s)" % read_timeout)
raise
# AppEngine doesn't have a version attr.
http_version = getattr(conn, '_http_vsn_str', 'HTTP/?')
log.debug("\"%s %s %s\" %s %s" % (method, url, http_version,
httplib_response.status,
httplib_response.length))
return httplib_response
def close(self):
"""
Close all pooled connections and disable the pool.
"""
# Disable access to the pool
old_pool, self.pool = self.pool, None
try:
while True:
conn = old_pool.get(block=False)
if conn:
conn.close()
except Empty:
pass # Done.
def is_same_host(self, url):
"""
Check if the given ``url`` is a member of the same host as this
connection pool.
"""
if url.startswith('/'):
return True
# TODO: Add optional support for socket.gethostbyname checking.
scheme, host, port = get_host(url)
# Use explicit default port for comparison when none is given
if self.port and not port:
port = port_by_scheme.get(scheme)
elif not self.port and port == port_by_scheme.get(scheme):
port = None
return (scheme, host, port) == (self.scheme, self.host, self.port)
def urlopen(self, method, url, body=None, headers=None, retries=3,
redirect=True, assert_same_host=True, timeout=_Default,
pool_timeout=None, release_conn=None, **response_kw):
"""
Get a connection from the pool and perform an HTTP request. This is the
lowest level call for making a request, so you'll need to specify all
the raw details.
.. note::
More commonly, it's appropriate to use a convenience method provided
by :class:`.RequestMethods`, such as :meth:`request`.
.. note::
`release_conn` will only behave as expected if
`preload_content=False` because we want to make
`preload_content=False` the default behaviour someday soon without
breaking backwards compatibility.
:param method:
HTTP request method (such as GET, POST, PUT, etc.)
:param body:
Data to send in the request body (useful for creating
POST requests, see HTTPConnectionPool.post_url for
more convenience).
:param headers:
Dictionary of custom headers to send, such as User-Agent,
If-None-Match, etc. If None, pool headers are used. If provided,
these headers completely replace any pool-specific headers.
:param retries:
Number of retries to allow before raising a MaxRetryError exception.
If `False`, then retries are disabled and any exception is raised
immediately.
:param redirect:
If True, automatically handle redirects (status codes 301, 302,
303, 307, 308). Each redirect counts as a retry. Disabling retries
will disable redirect, too.
:param assert_same_host:
If ``True``, will make sure that the host of the pool requests is
consistent else will raise HostChangedError. When False, you can
use the pool on an HTTP proxy and request foreign hosts.
:param timeout:
If specified, overrides the default timeout for this one
request. It may be a float (in seconds) or an instance of
:class:`urllib3.util.Timeout`.
:param pool_timeout:
If set and the pool is set to block=True, then this method will
block for ``pool_timeout`` seconds and raise EmptyPoolError if no
connection is available within the time period.
:param release_conn:
If False, then the urlopen call will not release the connection
back into the pool once a response is received (but will release if
you read the entire contents of the response such as when
`preload_content=True`). This is useful if you're not preloading
the response's content immediately. You will need to call
``r.release_conn()`` on the response ``r`` to return the connection
back into the pool. If None, it takes the value of
``response_kw.get('preload_content', True)``.
:param \**response_kw:
Additional parameters are passed to
:meth:`urllib3.response.HTTPResponse.from_httplib`
"""
if headers is None:
headers = self.headers
if retries < 0 and retries is not False:
raise MaxRetryError(self, url)
if release_conn is None:
release_conn = response_kw.get('preload_content', True)
# Check host
if assert_same_host and not self.is_same_host(url):
raise HostChangedError(self, url, retries - 1)
conn = None
# Merge the proxy headers. Only do this in HTTP. We have to copy the
# headers dict so we can safely change it without those changes being
# reflected in anyone else's copy.
if self.scheme == 'http':
headers = headers.copy()
headers.update(self.proxy_headers)
# Must keep the exception bound to a separate variable or else Python 3
# complains about UnboundLocalError.
err = None
try:
# Request a connection from the queue
conn = self._get_conn(timeout=pool_timeout)
# Make the request on the httplib connection object
httplib_response = self._make_request(conn, method, url,
timeout=timeout,
body=body, headers=headers)
# If we're going to release the connection in ``finally:``, then
# the request doesn't need to know about the connection. Otherwise
# it will also try to release it and we'll have a double-release
# mess.
response_conn = not release_conn and conn
# Import httplib's response into our own wrapper object
response = HTTPResponse.from_httplib(httplib_response,
pool=self,
connection=response_conn,
**response_kw)
# else:
# The connection will be put back into the pool when
# ``response.release_conn()`` is called (implicitly by
# ``response.read()``)
except Empty:
# Timed out by queue.
raise EmptyPoolError(self, "No pool connections are available.")
except (BaseSSLError, CertificateError) as e:
# Release connection unconditionally because there is no way to
# close it externally in case of exception.
release_conn = True
raise SSLError(e)
except (TimeoutError, HTTPException, SocketError) as e:
if conn:
# Discard the connection for these exceptions. It will be
# be replaced during the next _get_conn() call.
conn.close()
conn = None
if not retries:
if isinstance(e, TimeoutError):
# TimeoutError is exempt from MaxRetryError-wrapping.
# FIXME: ... Not sure why. Add a reason here.
raise
# Wrap unexpected exceptions with the most appropriate
# module-level exception and re-raise.
if isinstance(e, SocketError) and self.proxy:
raise ProxyError('Cannot connect to proxy.', e)
if retries is False:
raise ConnectionError('Connection failed.', e)
raise MaxRetryError(self, url, e)
# Keep track of the error for the retry warning.
err = e
finally:
if release_conn:
# Put the connection back to be reused. If the connection is
# expired then it will be None, which will get replaced with a
# fresh connection during _get_conn.
self._put_conn(conn)
if not conn:
# Try again
log.warning("Retrying (%d attempts remain) after connection "
"broken by '%r': %s" % (retries, err, url))
return self.urlopen(method, url, body, headers, retries - 1,
redirect, assert_same_host,
timeout=timeout, pool_timeout=pool_timeout,
release_conn=release_conn, **response_kw)
# Handle redirect?
redirect_location = redirect and response.get_redirect_location()
if redirect_location and retries is not False:
if response.status == 303:
method = 'GET'
log.info("Redirecting %s -> %s" % (url, redirect_location))
return self.urlopen(method, redirect_location, body, headers,
retries - 1, redirect, assert_same_host,
timeout=timeout, pool_timeout=pool_timeout,
release_conn=release_conn, **response_kw)
return response
class HTTPSConnectionPool(HTTPConnectionPool):
"""
Same as :class:`.HTTPConnectionPool`, but HTTPS.
When Python is compiled with the :mod:`ssl` module, then
:class:`.VerifiedHTTPSConnection` is used, which *can* verify certificates,
instead of :class:`.HTTPSConnection`.
:class:`.VerifiedHTTPSConnection` uses one of ``assert_fingerprint``,
``assert_hostname`` and ``host`` in this order to verify connections.
If ``assert_hostname`` is False, no verification is done.
The ``key_file``, ``cert_file``, ``cert_reqs``, ``ca_certs`` and
``ssl_version`` are only used if :mod:`ssl` is available and are fed into
:meth:`urllib3.util.ssl_wrap_socket` to upgrade the connection socket
into an SSL socket.
"""
scheme = 'https'
ConnectionCls = HTTPSConnection
def __init__(self, host, port=None,
strict=False, timeout=None, maxsize=1,
block=False, headers=None,
_proxy=None, _proxy_headers=None,
key_file=None, cert_file=None, cert_reqs=None,
ca_certs=None, ssl_version=None,
assert_hostname=None, assert_fingerprint=None,
**conn_kw):
if sys.version_info < (2, 7): # Python 2.6 or older
conn_kw.pop('source_address', None)
HTTPConnectionPool.__init__(self, host, port, strict, timeout, maxsize,
block, headers, _proxy, _proxy_headers, **conn_kw)
self.key_file = key_file
self.cert_file = cert_file
self.cert_reqs = cert_reqs
self.ca_certs = ca_certs
self.ssl_version = ssl_version
self.assert_hostname = assert_hostname
self.assert_fingerprint = assert_fingerprint
self.conn_kw = conn_kw
def _prepare_conn(self, conn):
"""
Prepare the ``connection`` for :meth:`urllib3.util.ssl_wrap_socket`
and establish the tunnel if proxy is used.
"""
if isinstance(conn, VerifiedHTTPSConnection):
conn.set_cert(key_file=self.key_file,
cert_file=self.cert_file,
cert_reqs=self.cert_reqs,
ca_certs=self.ca_certs,
assert_hostname=self.assert_hostname,
assert_fingerprint=self.assert_fingerprint)
conn.ssl_version = self.ssl_version
conn.conn_kw = self.conn_kw
if self.proxy is not None:
# Python 2.7+
try:
set_tunnel = conn.set_tunnel
except AttributeError: # Platform-specific: Python 2.6
set_tunnel = conn._set_tunnel
set_tunnel(self.host, self.port, self.proxy_headers)
# Establish tunnel connection early, because otherwise httplib
# would improperly set Host: header to proxy's IP:port.
conn.connect()
return conn
def _new_conn(self):
"""
Return a fresh :class:`httplib.HTTPSConnection`.
"""
self.num_connections += 1
log.info("Starting new HTTPS connection (%d): %s"
% (self.num_connections, self.host))
if not self.ConnectionCls or self.ConnectionCls is DummyConnection:
# Platform-specific: Python without ssl
raise SSLError("Can't connect to HTTPS URL because the SSL "
"module is not available.")
actual_host = self.host
actual_port = self.port
if self.proxy is not None:
actual_host = self.proxy.host
actual_port = self.proxy.port
extra_params = {}
if not six.PY3: # Python 2
extra_params['strict'] = self.strict
extra_params.update(self.conn_kw)
conn = self.ConnectionCls(host=actual_host, port=actual_port,
timeout=self.timeout.connect_timeout,
**extra_params)
if self.proxy is not None:
# Enable Nagle's algorithm for proxies, to avoid packet
# fragmentation.
conn.tcp_nodelay = 0
return self._prepare_conn(conn)
def connection_from_url(url, **kw):
"""
Given a url, return an :class:`.ConnectionPool` instance of its host.
This is a shortcut for not having to parse out the scheme, host, and port
of the url before creating an :class:`.ConnectionPool` instance.
:param url:
Absolute URL string that must include the scheme. Port is optional.
:param \**kw:
Passes additional parameters to the constructor of the appropriate
:class:`.ConnectionPool`. Useful for specifying things like
timeout, maxsize, headers, etc.
Example: ::
>>> conn = connection_from_url('http://google.com/')
>>> r = conn.request('GET', '/')
"""
scheme, host, port = get_host(url)
if scheme == 'https':
return HTTPSConnectionPool(host, port=port, **kw)
else:
return HTTPConnectionPool(host, port=port, **kw)