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poolmanager.py
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from __future__ import absolute_import import collections import functools import logging from ._collections import HTTPHeaderDict, RecentlyUsedContainer from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool from .connectionpool import port_by_scheme from .exceptions import LocationValueError, MaxRetryError, ProxySchemeUnknown from .packages import six from .packages.six.moves.urllib.parse import urljoin from .request import RequestMethods from .util.url import parse_url from .util.retry import Retry __all__ = ['PoolManager', 'ProxyManager', 'proxy_from_url'] log = logging.getLogger(__name__) SSL_KEYWORDS = ('key_file', 'cert_file', 'cert_reqs', 'ca_certs', 'ssl_version', 'ca_cert_dir', 'ssl_context') # All known keyword arguments that could be provided to the pool manager, its # pools, or the underlying connections. This is used to construct a pool key. _key_fields = ( 'key_scheme', # str 'key_host', # str 'key_port', # int 'key_timeout', # int or float or Timeout 'key_retries', # int or Retry 'key_strict', # bool 'key_block', # bool 'key_source_address', # str 'key_key_file', # str 'key_cert_file', # str 'key_cert_reqs', # str 'key_ca_certs', # str 'key_ssl_version', # str 'key_ca_cert_dir', # str 'key_ssl_context', # instance of ssl.SSLContext or urllib3.util.ssl_.SSLContext 'key_maxsize', # int 'key_headers', # dict 'key__proxy', # parsed proxy url 'key__proxy_headers', # dict 'key_socket_options', # list of (level (int), optname (int), value (int or str)) tuples 'key__socks_options', # dict 'key_assert_hostname', # bool or string 'key_assert_fingerprint', # str 'key_server_hostname', #str ) #: The namedtuple class used to construct keys for the connection pool. #: All custom key schemes should include the fields in this key at a minimum. PoolKey = collections.namedtuple('PoolKey', _key_fields) def _default_key_normalizer(key_class, request_context): """ Create a pool key out of a request context dictionary. According to RFC 3986, both the scheme and host are case-insensitive. Therefore, this function normalizes both before constructing the pool key for an HTTPS request. If you wish to change this behaviour, provide alternate callables to ``key_fn_by_scheme``. :param key_class: The class to use when constructing the key. This should be a namedtuple with the ``scheme`` and ``host`` keys at a minimum. :type key_class: namedtuple :param request_context: A dictionary-like object that contain the context for a request. :type request_context: dict :return: A namedtuple that can be used as a connection pool key. :rtype: PoolKey """ # Since we mutate the dictionary, make a copy first context = request_context.copy() context['scheme'] = context['scheme'].lower() context['host'] = context['host'].lower() # These are both dictionaries and need to be transformed into frozensets for key in ('headers', '_proxy_headers', '_socks_options'): if key in context and context[key] is not None: context[key] = frozenset(context[key].items()) # The socket_options key may be a list and needs to be transformed into a # tuple. socket_opts = context.get('socket_options') if socket_opts is not None: context['socket_options'] = tuple(socket_opts) # Map the kwargs to the names in the namedtuple - this is necessary since # namedtuples can't have fields starting with '_'. for key in list(context.keys()): context['key_' + key] = context.pop(key) # Default to ``None`` for keys missing from the context for field in key_class._fields: if field not in context: context[field] = None return key_class(**context) #: A dictionary that maps a scheme to a callable that creates a pool key. #: This can be used to alter the way pool keys are constructed, if desired. #: Each PoolManager makes a copy of this dictionary so they can be configured #: globally here, or individually on the instance. key_fn_by_scheme = { 'http': functools.partial(_default_key_normalizer, PoolKey), 'https': functools.partial(_default_key_normalizer, PoolKey), } pool_classes_by_scheme = { 'http': HTTPConnectionPool, 'https': HTTPSConnectionPool, } class PoolManager(RequestMethods): """ Allows for arbitrary requests while transparently keeping track of necessary connection pools for you. :param num_pools: Number of connection pools to cache before discarding the least recently used pool. :param headers: Headers to include with all requests, unless other headers are given explicitly. :param \\**connection_pool_kw: Additional parameters are used to create fresh :class:`urllib3.connectionpool.ConnectionPool` instances. Example:: >>> manager = PoolManager(num_pools=2) >>> r = manager.request('GET', 'http://google.com/') >>> r = manager.request('GET', 'http://google.com/mail') >>> r = manager.request('GET', 'http://yahoo.com/') >>> len(manager.pools) 2 """ proxy = None def __init__(self, num_pools=10, headers=None, **connection_pool_kw): RequestMethods.__init__(self, headers) self.connection_pool_kw = connection_pool_kw self.pools = RecentlyUsedContainer(num_pools, dispose_func=lambda p: p.close()) # Locally set the pool classes and keys so other PoolManagers can # override them. self.pool_classes_by_scheme = pool_classes_by_scheme self.key_fn_by_scheme = key_fn_by_scheme.copy() def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.clear() # Return False to re-raise any potential exceptions return False def _new_pool(self, scheme, host, port, request_context=None): """ Create a new :class:`ConnectionPool` based on host, port, scheme, and any additional pool keyword arguments. If ``request_context`` is provided, it is provided as keyword arguments to the pool class used. This method is used to actually create the connection pools handed out by :meth:`connection_from_url` and companion methods. It is intended to be overridden for customization. """ pool_cls = self.pool_classes_by_scheme[scheme] if request_context is None: request_context = self.connection_pool_kw.copy() # Although the context has everything necessary to create the pool, # this function has historically only used the scheme, host, and port # in the positional args. When an API change is acceptable these can # be removed. for key in ('scheme', 'host', 'port'): request_context.pop(key, None) if scheme == 'http': for kw in SSL_KEYWORDS: request_context.pop(kw, None) return pool_cls(host, port, **request_context) def clear(self): """ Empty our store of pools and direct them all to close. This will not affect in-flight connections, but they will not be re-used after completion. """ self.pools.clear() def connection_from_host(self, host, port=None, scheme='http', pool_kwargs=None): """ Get a :class:`ConnectionPool` based on the host, port, and scheme. If ``port`` isn't given, it will be derived from the ``scheme`` using ``urllib3.connectionpool.port_by_scheme``. If ``pool_kwargs`` is provided, it is merged with the instance's ``connection_pool_kw`` variable and used to create the new connection pool, if one is needed. """ if not host: raise LocationValueError("No host specified.") request_context = self._merge_pool_kwargs(pool_kwargs) request_context['scheme'] = scheme or 'http' if not port: port = port_by_scheme.get(request_context['scheme'].lower(), 80) request_context['port'] = port request_context['host'] = host return self.connection_from_context(request_context) def connection_from_context(self, request_context): """ Get a :class:`ConnectionPool` based on the request context. ``request_context`` must at least contain the ``scheme`` key and its value must be a key in ``key_fn_by_scheme`` instance variable. """ scheme = request_context['scheme'].lower() pool_key_constructor = self.key_fn_by_scheme[scheme] pool_key = pool_key_constructor(request_context) return self.connection_from_pool_key(pool_key, request_context=request_context) def connection_from_pool_key(self, pool_key, request_context=None): """ Get a :class:`ConnectionPool` based on the provided pool key. ``pool_key`` should be a namedtuple that only contains immutable objects. At a minimum it must have the ``scheme``, ``host``, and ``port`` fields. """ with self.pools.lock: # If the scheme, host, or port doesn't match existing open # connections, open a new ConnectionPool. pool = self.pools.get(pool_key) if pool: return pool # Make a fresh ConnectionPool of the desired type scheme = request_context['scheme'] host = request_context['host'] port = request_context['port'] pool = self._new_pool(scheme, host, port, request_context=request_context) self.pools[pool_key] = pool return pool def connection_from_url(self, url, pool_kwargs=None): """ Similar to :func:`urllib3.connectionpool.connection_from_url`. If ``pool_kwargs`` is not provided and a new pool needs to be constructed, ``self.connection_pool_kw`` is used to initialize the :class:`urllib3.connectionpool.ConnectionPool`. If ``pool_kwargs`` is provided, it is used instead. Note that if a new pool does not need to be created for the request, the provided ``pool_kwargs`` are not used. """ u = parse_url(url) return self.connection_from_host(u.host, port=u.port, scheme=u.scheme, pool_kwargs=pool_kwargs) def _merge_pool_kwargs(self, override): """ Merge a dictionary of override values for self.connection_pool_kw. This does not modify self.connection_pool_kw and returns a new dict. Any keys in the override dictionary with a value of ``None`` are removed from the merged dictionary. """ base_pool_kwargs = self.connection_pool_kw.copy() if override: for key, value in override.items(): if value is None: try: del base_pool_kwargs[key] except KeyError: pass else: base_pool_kwargs[key] = value return base_pool_kwargs def urlopen(self, method, url, redirect=True, **kw): """ Same as :meth:`urllib3.connectionpool.HTTPConnectionPool.urlopen` with custom cross-host redirect logic and only sends the request-uri portion of the ``url``. The given ``url`` parameter must be absolute, such that an appropriate :class:`urllib3.connectionpool.ConnectionPool` can be chosen for it. """ u = parse_url(url) conn = self.connection_from_host(u.host, port=u.port, scheme=u.scheme) kw['assert_same_host'] = False kw['redirect'] = False if 'headers' not in kw: kw['headers'] = self.headers.copy() if self.proxy is not None and u.scheme == "http": response = conn.urlopen(method, url, **kw) else: response = conn.urlopen(method, u.request_uri, **kw) redirect_location = redirect and response.get_redirect_location() if not redirect_location: return response # Support relative URLs for redirecting. redirect_location = urljoin(url, redirect_location) if response.status == 303: # Change the method according to RFC 9110, Section 15.4.4. method = 'GET' # And lose the body not to transfer anything sensitive. kw["body"] = None kw["headers"] = HTTPHeaderDict(kw["headers"])._prepare_for_method_change() retries = kw.get('retries') if not isinstance(retries, Retry): retries = Retry.from_int(retries, redirect=redirect) # Strip headers marked as unsafe to forward to the redirected location. # Check remove_headers_on_redirect to avoid a potential network call within # conn.is_same_host() which may use socket.gethostbyname() in the future. if (retries.remove_headers_on_redirect and not conn.is_same_host(redirect_location)): headers = list(six.iterkeys(kw['headers'])) for header in headers: if header.lower() in retries.remove_headers_on_redirect: kw['headers'].pop(header, None) try: retries = retries.increment(method, url, response=response, _pool=conn) except MaxRetryError: if retries.raise_on_redirect: raise return response kw['retries'] = retries kw['redirect'] = redirect log.info("Redirecting %s -> %s", url, redirect_location) return self.urlopen(method, redirect_location, **kw) class ProxyManager(PoolManager): """ Behaves just like :class:`PoolManager`, but sends all requests through the defined proxy, using the CONNECT method for HTTPS URLs. :param proxy_url: The URL of the proxy to be used. :param proxy_headers: A dictionary containing headers that will be sent to the proxy. In case of HTTP they are being sent with each request, while in the HTTPS/CONNECT case they are sent only once. Could be used for proxy authentication. Example: >>> proxy = urllib3.ProxyManager('http://localhost:3128/') >>> r1 = proxy.request('GET', 'http://google.com/') >>> r2 = proxy.request('GET', 'http://httpbin.org/') >>> len(proxy.pools) 1 >>> r3 = proxy.request('GET', 'https://httpbin.org/') >>> r4 = proxy.request('GET', 'https://twitter.com/') >>> len(proxy.pools) 3 """ def __init__(self, proxy_url, num_pools=10, headers=None, proxy_headers=None, **connection_pool_kw): if isinstance(proxy_url, HTTPConnectionPool): proxy_url = '%s://%s:%i' % (proxy_url.scheme, proxy_url.host, proxy_url.port) proxy = parse_url(proxy_url) if not proxy.port: port = port_by_scheme.get(proxy.scheme, 80) proxy = proxy._replace(port=port) if proxy.scheme not in ("http", "https"): raise ProxySchemeUnknown(proxy.scheme) self.proxy = proxy self.proxy_headers = proxy_headers or {} connection_pool_kw['_proxy'] = self.proxy connection_pool_kw['_proxy_headers'] = self.proxy_headers super(ProxyManager, self).__init__( num_pools, headers, **connection_pool_kw) def connection_from_host(self, host, port=None, scheme='http', pool_kwargs=None): if scheme == "https": return super(ProxyManager, self).connection_from_host( host, port, scheme, pool_kwargs=pool_kwargs) return super(ProxyManager, self).connection_from_host( self.proxy.host, self.proxy.port, self.proxy.scheme, pool_kwargs=pool_kwargs) def _set_proxy_headers(self, url, headers=None): """ Sets headers needed by proxies: specifically, the Accept and Host headers. Only sets headers not provided by the user. """ headers_ = {'Accept': '*/*'} netloc = parse_url(url).netloc if netloc: headers_['Host'] = netloc if headers: headers_.update(headers) return headers_ def urlopen(self, method, url, redirect=True, **kw): "Same as HTTP(S)ConnectionPool.urlopen, ``url`` must be absolute." u = parse_url(url) if u.scheme == "http": # For proxied HTTPS requests, httplib sets the necessary headers # on the CONNECT to the proxy. For HTTP, we'll definitely # need to set 'Host' at the very least. headers = kw.get('headers', self.headers) kw['headers'] = self._set_proxy_headers(url, headers) return super(ProxyManager, self).urlopen(method, url, redirect=redirect, **kw) def proxy_from_url(url, **kw): return ProxyManager(proxy_url=url, **kw)