# 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)