# urllib3.contrib package

These modules implement various extra features, that may not be ready for prime time or that require optional third-party dependencies.

## urllib3.contrib.appengine module

This module provides a pool manager that uses Google App Engine’s URLFetch Service.

Example usage:

    from urllib3 import PoolManager
    from urllib3.contrib.appengine import AppEngineManager, is_appengine_sandbox

    if is_appengine_sandbox():
        # AppEngineManager uses AppEngine's URLFetch API behind the scenes
        http = AppEngineManager()
    else:
        # PoolManager uses a socket-level API behind the scenes
        http = PoolManager()

    r = http.request('GET', 'https://google.com/')

There are limitations to the URLFetch service and it may not be the best choice for your application. There are three options for using urllib3 on Google App Engine:

1. You can use `AppEngineManager` with URLFetch. URLFetch is cost-effective in many circumstances as long as your usage is within the limitations.

2. You can use a normal `PoolManager` by enabling sockets. Sockets also have limitations and restrictions and have a lower free quota than URLFetch. To use sockets, be sure to specify the following in your `app.yaml`:

       env_variables:
           GAE_USE_SOCKETS_HTTPLIB : 'true'

3. If you are using App Engine Flexible, you can use the standard `PoolManager` without any configuration or special environment variables.

class `urllib3.contrib.appengine.``AppEngineManager`(headers=None, retries=None, validate_certificate=True, urlfetch_retries=True)

  Bases: `urllib3.request.RequestMethods`

  Connection manager for Google App Engine sandbox applications.

  This manager uses the URLFetch service directly instead of using the emulated httplib, and is subject to URLFetch limitations as described in the App Engine documentation here.

  Notably it will raise an `AppEnginePlatformError` if:
    - URLFetch is not available.
    - If you attempt to use this on App Engine Flexible, as full socket support is available.
    - If a request size is more than 10 megabytes.
    - If a response size is more than 32 megabtyes.
    - If you use an unsupported request method such as OPTIONS.

  Beyond those cases, it will raise normal urllib3 errors.

  `urlopen`(method, url, body=None, headers=None, retries=None, redirect=True, timeout=<object object>, **response_kw)

exception `urllib3.contrib.appengine.``AppEnginePlatformError`

  Bases: `urllib3.exceptions.HTTPError`

exception `urllib3.contrib.appengine.``AppEnginePlatformWarning`

  Bases: `urllib3.exceptions.HTTPWarning`

`urllib3.contrib.appengine.``is_appengine`()

`urllib3.contrib.appengine.``is_appengine_sandbox`()

`urllib3.contrib.appengine.``is_local_appengine`()

`urllib3.contrib.appengine.``is_prod_appengine`()

`urllib3.contrib.appengine.``is_prod_appengine_mvms`()

## urllib3.contrib.ntlmpool module

NTLM authenticating pool, contributed by erikcederstran

Issue #10, see: http://code.google.com/p/urllib3/issues/detail?id=10

class `urllib3.contrib.ntlmpool.``NTLMConnectionPool`(user, pw, authurl, *args, **kwargs)

  Bases: `urllib3.connectionpool.HTTPSConnectionPool`

  Implements an NTLM authentication version of an urllib3 connection pool

  `scheme` = 'https'
  `urlopen`(method, url, body=None, headers=None, retries=3, redirect=True, assert_same_host=True)

## urllib3.contrib.pyopenssl module

SSL with SNI-support for Python 2. Follow these instructions if you would like to verify SSL certificates in Python 2. Note, the default libraries do not do certificate checking; you need to do additional work to validate certificates yourself.

This needs the following packages installed:

- pyOpenSSL (tested with 16.0.0)
- cryptography (minimum 1.3.4, from pyopenssl)
- idna (minimum 2.0, from cryptography)

However, pyopenssl depends on cryptography, which depends on idna, so while we use all three directly here we end up having relatively few packages required.

You can install them with the following command:

> pip install pyopenssl cryptography idna

To activate certificate checking, call `inject_into_urllib3()` from your Python code before you begin making HTTP requests. This can be done in a `sitecustomize` module, or at any other time before your application begins using `urllib3`, like this:

    try:
        import urllib3.contrib.pyopenssl
        urllib3.contrib.pyopenssl.inject_into_urllib3()
    except ImportError:
        pass

Now you can use `urllib3` as you normally would, and it will support SNI when the required modules are installed.

Activating this module also has the positive side effect of disabling SSL/TLS compression in Python 2 (see CRIME attack).

If you want to configure the default list of supported cipher suites, you can set the `urllib3.contrib.pyopenssl.DEFAULT_SSL_CIPHER_LIST` variable.

`urllib3.contrib.pyopenssl.``inject_into_urllib3`()

  Monkey-patch urllib3 with PyOpenSSL-backed SSL-support.

`urllib3.contrib.pyopenssl.``extract_from_urllib3`()

  Undo monkey-patching by `inject_into_urllib3()`.

## urllib3.contrib.socks module

This module contains provisional support for SOCKS proxies from within urllib3. This module supports SOCKS4 (specifically the SOCKS4A variant) and SOCKS5. To enable its functionality, either install PySocks or install this module with the `socks` extra.

The SOCKS implementation supports the full range of urllib3 features. It also supports the following SOCKS features:

- SOCKS4
- SOCKS4a
- SOCKS5
- Usernames and passwords for the SOCKS proxy

Known Limitations:

- Currently PySocks does not support contacting remote websites via literal IPv6 addresses. Any such connection attempt will fail. You must use a domain name.
- Currently PySocks does not support IPv6 connections to the SOCKS proxy. Any such connection attempt will fail.

class `urllib3.contrib.socks.``SOCKSConnection`(*args, **kwargs)

  Bases: `urllib3.connection.HTTPConnection`

  A plain-text HTTP connection that connects via a SOCKS proxy.

class `urllib3.contrib.socks.``SOCKSHTTPConnectionPool`(host, port=None, strict=False, timeout=<object object>, maxsize=1, block=False, headers=None, retries=None, _proxy=None, _proxy_headers=None, **conn_kw)

  Bases: `urllib3.connectionpool.HTTPConnectionPool`

  `ConnectionCls`

    alias of `SOCKSConnection`

class `urllib3.contrib.socks.``SOCKSHTTPSConnection`(*args, **kwargs)

  Bases: `urllib3.contrib.socks.SOCKSConnection`, `urllib3.connection.VerifiedHTTPSConnection`

class `urllib3.contrib.socks.``SOCKSHTTPSConnectionPool`(host, port=None, strict=False, timeout=<object object>, maxsize=1, block=False, headers=None, retries=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, ca_cert_dir=None, **conn_kw)

  Bases: `urllib3.connectionpool.HTTPSConnectionPool`

  `ConnectionCls`

    alias of `SOCKSHTTPSConnection`

class `urllib3.contrib.socks.``SOCKSProxyManager`(proxy_url, username=None, password=None, num_pools=10, headers=None, **connection_pool_kw)

  Bases: `urllib3.poolmanager.PoolManager`

  A version of the urllib3 ProxyManager that routes connections via the defined SOCKS proxy.

  `pool_classes_by_scheme` = {'http': <class 'urllib3.contrib.socks.SOCKSHTTPConnectionPool'>, 'https': <class 'urllib3.contrib.socks.SOCKSHTTPSConnectionPool'>}