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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, port_by_scheme from .exceptions import ( LocationValueError, MaxRetryError, ProxySchemeUnknown, ProxySchemeUnsupported, URLSchemeUnknown, ) import six from six.moves.urllib.parse import urljoin from .request import RequestMethods from .util.proxy import connection_requires_http_tunnel from .util.retry import Retry from .util.url import parse_url __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", "key_password", ) # 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_key_password", # 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__proxy_config", # class "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) _proxy_config_fields = ("ssl_context", "use_forwarding_for_https") ProxyConfig = collections.namedtuple("ProxyConfig", _proxy_config_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 proxy_config = 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:`urllib3.connectionpool.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:`urllib3.connectionpool.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:`urllib3.connectionpool.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.get(scheme) if not pool_key_constructor: raise URLSchemeUnknown(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:`urllib3.connectionpool.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 _proxy_requires_url_absolute_form(self, parsed_url): """ Indicates if the proxy requires the complete destination URL in the request. Normally this is only needed when not using an HTTP CONNECT tunnel. """ if self.proxy is None: return False return not connection_requires_http_tunnel( self.proxy, self.proxy_config, parsed_url.scheme ) def _validate_proxy_scheme_url_selection(self, url_scheme): """ Validates that were not attempting to do TLS in TLS connections on Python2 or with unsupported SSL implementations. """ if self.proxy is None or url_scheme != "https": return if self.proxy.scheme != "https": return if six.PY2 and not self.proxy_config.use_forwarding_for_https: raise ProxySchemeUnsupported( "Contacting HTTPS destinations through HTTPS proxies " "'via CONNECT tunnels' is not supported in Python 2" ) def urlopen(self, method, url, redirect=True, **kw): """ Same as :meth:`urllib3.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) self._validate_proxy_scheme_url_selection(u.scheme) 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_requires_url_absolute_form(u): 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: response.drain_conn() raise return response kw["retries"] = retries kw["redirect"] = redirect log.info("Redirecting %s -> %s", url, redirect_location) response.drain_conn() 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. :param proxy_ssl_context: The proxy SSL context is used to establish the TLS connection to the proxy when using HTTPS proxies. :param use_forwarding_for_https: (Defaults to False) If set to True will forward requests to the HTTPS proxy to be made on behalf of the client instead of creating a TLS tunnel via the CONNECT method. **Enabling this flag means that request and response headers and content will be visible from the HTTPS proxy** whereas tunneling keeps request and response headers and content private. IP address, target hostname, SNI, and port are always visible to an HTTPS proxy even when this flag is disabled. 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, proxy_ssl_context=None, use_forwarding_for_https=False, **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 proxy.scheme not in ("http", "https"): raise ProxySchemeUnknown(proxy.scheme) if not proxy.port: port = port_by_scheme.get(proxy.scheme, 80) proxy = proxy._replace(port=port) self.proxy = proxy self.proxy_headers = proxy_headers or {} self.proxy_ssl_context = proxy_ssl_context self.proxy_config = ProxyConfig(proxy_ssl_context, use_forwarding_for_https) connection_pool_kw["_proxy"] = self.proxy connection_pool_kw["_proxy_headers"] = self.proxy_headers connection_pool_kw["_proxy_config"] = self.proxy_config 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 not connection_requires_http_tunnel(self.proxy, self.proxy_config, u.scheme): # For connections using HTTP CONNECT, httplib sets the necessary # headers on the CONNECT to the proxy. If we're not using CONNECT, # 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)