# urllib3/connectionpool.py # Copyright 2008-2012 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 logging import socket from socket import error as SocketError, timeout as SocketTimeout try: # Python 3 from http.client import HTTPConnection, HTTPException from http.client import HTTP_PORT, HTTPS_PORT except ImportError: from httplib import HTTPConnection, HTTPException from httplib import HTTP_PORT, HTTPS_PORT try: # Python 3 from queue import LifoQueue, Empty, Full except ImportError: from Queue import LifoQueue, Empty, Full try: # Compiled with SSL? HTTPSConnection = object BaseSSLError = None ssl = None try: # Python 3 from http.client import HTTPSConnection except ImportError: from httplib import HTTPSConnection import ssl BaseSSLError = ssl.SSLError except (ImportError, AttributeError): pass from .request import RequestMethods from .response import HTTPResponse from .util import get_host, is_connection_dropped from .exceptions import ( EmptyPoolError, HostChangedError, MaxRetryError, SSLError, TimeoutError, ) from .packages.ssl_match_hostname import match_hostname, CertificateError from .packages import six xrange = six.moves.xrange log = logging.getLogger(__name__) _Default = object() port_by_scheme = { 'http': HTTP_PORT, 'https': HTTPS_PORT, } ## Connection objects (extension of httplib) class VerifiedHTTPSConnection(HTTPSConnection): """ Based on httplib.HTTPSConnection but wraps the socket with SSL certification. """ cert_reqs = None ca_certs = None def set_cert(self, key_file=None, cert_file=None, cert_reqs='CERT_NONE', ca_certs=None): ssl_req_scheme = { 'CERT_NONE': ssl.CERT_NONE, 'CERT_OPTIONAL': ssl.CERT_OPTIONAL, 'CERT_REQUIRED': ssl.CERT_REQUIRED } self.key_file = key_file self.cert_file = cert_file self.cert_reqs = ssl_req_scheme.get(cert_reqs) or ssl.CERT_NONE self.ca_certs = ca_certs def connect(self): # Add certificate verification sock = socket.create_connection((self.host, self.port), self.timeout) # Wrap socket using verification with the root certs in # trusted_root_certs self.sock = ssl.wrap_socket(sock, self.key_file, self.cert_file, cert_reqs=self.cert_reqs, ca_certs=self.ca_certs) if self.ca_certs: match_hostname(self.sock.getpeercert(), self.host) ## 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): self.host = host self.port = port def __str__(self): return '%s(host=%r, port=%r)' % (type(self).__name__, self.host, self.port) 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`. :param timeout: Socket timeout for each individual connection, can be a float. None disables timeout. :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. """ scheme = 'http' def __init__(self, host, port=None, strict=False, timeout=None, maxsize=1, block=False, headers=None): super(HTTPConnectionPool, self).__init__(host, port) self.strict = strict self.timeout = timeout self.pool = self.QueueCls(maxsize) self.block = block self.headers = 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 def _new_conn(self): """ Return a fresh :class:`httplib.HTTPConnection`. """ self.num_connections += 1 log.info("Starting new HTTP connection (%d): %s" % (self.num_connections, self.host)) return HTTPConnection(host=self.host, port=self.port) 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) # 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() 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 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 discarded because we exceeded maxsize. If connections are discarded frequently, then maxsize should be increased. """ try: self.pool.put(conn, block=False) except Full: # This should never happen if self.block == True log.warning("HttpConnectionPool is full, discarding connection: %s" % self.host) def _make_request(self, conn, method, url, timeout=_Default, **httplib_request_kw): """ Perform a request on a given httplib connection object taken from our pool. """ self.num_requests += 1 if timeout is _Default: timeout = self.timeout conn.timeout = timeout # This only does anything in Py26+ conn.request(method, url, **httplib_request_kw) # Set timeout sock = getattr(conn, 'sock', False) # AppEngine doesn't have sock attr. if sock: sock.settimeout(timeout) httplib_response = conn.getresponse() # 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 is_same_host(self, url): """ Check if the given ``url`` is a member of the same host as this connection pool. """ # TODO: Add optional support for socket.gethostbyname checking. scheme, host, port = get_host(url) if self.port and not port: # Use explicit default port for comparison when none is given. port = port_by_scheme.get(scheme) return (url.startswith('/') or (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. :param redirect: Automatically handle redirects (status codes 301, 302, 303, 307), each redirect counts as a retry. :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. :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: raise MaxRetryError(self, url) if timeout is _Default: timeout = self.timeout 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): host = "%s://%s" % (self.scheme, self.host) if self.port: host = "%s:%d" % (host, self.port) raise HostChangedError(self, url, retries - 1) conn = None try: # Request a connection from the queue # (Could raise SocketError: Bad file descriptor) 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 as e: # Timed out by queue raise TimeoutError(self, "Request timed out. (pool_timeout=%s)" % pool_timeout) except SocketTimeout as e: # Timed out by socket raise TimeoutError(self, "Request timed out. (timeout=%s)" % timeout) except BaseSSLError as e: # SSL certificate error raise SSLError(e) except CertificateError as e: # Name mismatch raise SSLError(e) except (HTTPException, SocketError) as e: # Connection broken, discard. It will be replaced next _get_conn(). conn = None # This is necessary so we can access e below err = e finally: if conn and release_conn: # Put the connection back to be reused self._put_conn(conn) if not conn: log.warn("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) # Try again # Handle redirect? redirect_location = redirect and response.get_redirect_location() if redirect_location: log.info("Redirecting %s -> %s" % (url, redirect_location)) return self.urlopen(method, redirect_location, body, headers, retries - 1, redirect, assert_same_host) 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:httplib.HTTPSConnection`. The ``key_file``, ``cert_file``, ``cert_reqs``, and ``ca_certs`` parameters are only used if :mod:`ssl` is available and are fed into :meth:`ssl.wrap_socket` to upgrade the connection socket into an SSL socket. """ scheme = 'https' def __init__(self, host, port=None, strict=False, timeout=None, maxsize=1, block=False, headers=None, key_file=None, cert_file=None, cert_reqs='CERT_NONE', ca_certs=None): super(HTTPSConnectionPool, self).__init__(host, port, strict, timeout, maxsize, block, headers) self.key_file = key_file self.cert_file = cert_file self.cert_reqs = cert_reqs self.ca_certs = ca_certs 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 ssl: # Platform-specific: Python compiled without +ssl if not HTTPSConnection or HTTPSConnection is object: raise SSLError("Can't connect to HTTPS URL because the SSL " "module is not available.") return HTTPSConnection(host=self.host, port=self.port) connection = VerifiedHTTPSConnection(host=self.host, port=self.port) connection.set_cert(key_file=self.key_file, cert_file=self.cert_file, cert_reqs=self.cert_reqs, ca_certs=self.ca_certs) return connection 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)