Add 'requests' library to third_party.

third_party/requests/sessions.py

Index: third_party/requests/sessions.py
diff --git a/third_party/requests/sessions.py b/third_party/requests/sessions.py
new file mode 100644
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+++ b/third_party/requests/sessions.py
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+# -*- coding: utf-8 -*-
+
+"""
+requests.session
+~~~~~~~~~~~~~~~~
+
+This module provides a Session object to manage and persist settings across
+requests (cookies, auth, proxies).
+
+"""
+import os
+from collections import Mapping
+from datetime import datetime
+
+from .compat import cookielib, OrderedDict, urljoin, urlparse
+from .cookies import cookiejar_from_dict, extract_cookies_to_jar, RequestsCookieJar
+from .models import Request, PreparedRequest
+from .hooks import default_hooks, dispatch_hook
+from .utils import to_key_val_list, default_headers
+from .exceptions import TooManyRedirects, InvalidSchema
+from .structures import CaseInsensitiveDict
+
+from .adapters import HTTPAdapter
+
+from .utils import requote_uri, get_environ_proxies, get_netrc_auth
+
+from .status_codes import codes
+REDIRECT_STATI = (
+    codes.moved, # 301
+    codes.found, # 302
+    codes.other, # 303
+    codes.temporary_moved, # 307
+)
+DEFAULT_REDIRECT_LIMIT = 30
+
+
+def merge_setting(request_setting, session_setting, dict_class=OrderedDict):
+    """
+    Determines appropriate setting for a given request, taking into account the
+    explicit setting on that request, and the setting in the session. If a
+    setting is a dictionary, they will be merged together using `dict_class`
+    """
+
+    if session_setting is None:
+        return request_setting
+
+    if request_setting is None:
+        return session_setting
+
+    # Bypass if not a dictionary (e.g. verify)
+    if not (
+            isinstance(session_setting, Mapping) and
+            isinstance(request_setting, Mapping)
+    ):
+        return request_setting
+
+    merged_setting = dict_class(to_key_val_list(session_setting))
+    merged_setting.update(to_key_val_list(request_setting))
+
+    # Remove keys that are set to None.
+    for (k, v) in request_setting.items():
+        if v is None:
+            del merged_setting[k]
+
+    return merged_setting
+
+
+class SessionRedirectMixin(object):
+    def resolve_redirects(self, resp, req, stream=False, timeout=None,
+                          verify=True, cert=None, proxies=None):
+        """Receives a Response. Returns a generator of Responses."""
+
+        i = 0
+        prepared_request = PreparedRequest()
+        prepared_request.body = req.body
+        prepared_request.headers = req.headers.copy()
+        prepared_request.hooks = req.hooks
+        prepared_request.method = req.method
+        prepared_request.url = req.url
+
+        # ((resp.status_code is codes.see_other))
+        while (('location' in resp.headers and resp.status_code in REDIRECT_STATI)):
+
+            resp.content  # Consume socket so it can be released
+
+            if i >= self.max_redirects:
+                raise TooManyRedirects('Exceeded %s redirects.' % self.max_redirects)
+
+            # Release the connection back into the pool.
+            resp.close()
+
+            url = resp.headers['location']
+            method = prepared_request.method
+
+            # Handle redirection without scheme (see: RFC 1808 Section 4)
+            if url.startswith('//'):
+                parsed_rurl = urlparse(resp.url)
+                url = '%s:%s' % (parsed_rurl.scheme, url)
+
+            # Facilitate non-RFC2616-compliant 'location' headers
+            # (e.g. '/path/to/resource' instead of 'http://domain.tld/path/to/resource')
+            # Compliant with RFC3986, we percent encode the url.
+            if not urlparse(url).netloc:
+                url = urljoin(resp.url, requote_uri(url))
+            else:
+                url = requote_uri(url)
+
+            prepared_request.url = url
+
+            # http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.4
+            if (resp.status_code == codes.see_other and
+                    prepared_request.method != 'HEAD'):
+                method = 'GET'
+
+            # Do what the browsers do, despite standards...
+            if (resp.status_code in (codes.moved, codes.found) and
+                    prepared_request.method not in ('GET', 'HEAD')):
+                method = 'GET'
+
+            prepared_request.method = method
+
+            # https://github.com/kennethreitz/requests/issues/1084
+            if resp.status_code not in (codes.temporary, codes.resume):
+                if 'Content-Length' in prepared_request.headers:
+                    del prepared_request.headers['Content-Length']
+
+                prepared_request.body = None
+
+            headers = prepared_request.headers
+            try:
+                del headers['Cookie']
+            except KeyError:
+                pass
+
+            prepared_request.prepare_cookies(self.cookies)
+
+            resp = self.send(
+                prepared_request,
+                stream=stream,
+                timeout=timeout,
+                verify=verify,
+                cert=cert,
+                proxies=proxies,
+                allow_redirects=False,
+            )
+
+            extract_cookies_to_jar(self.cookies, prepared_request, resp.raw)
+
+            i += 1
+            yield resp
+
+
+class Session(SessionRedirectMixin):
+    """A Requests session.
+
+    Provides cookie persistience, connection-pooling, and configuration.
+
+    Basic Usage::
+
+      >>> import requests
+      >>> s = requests.Session()
+      >>> s.get('http://httpbin.org/get')
+      200
+    """
+
+    __attrs__ = [
+        'headers', 'cookies', 'auth', 'timeout', 'proxies', 'hooks',
+        'params', 'verify', 'cert', 'prefetch', 'adapters', 'stream',
+        'trust_env', 'max_redirects']
+
+    def __init__(self):
+
+        #: A case-insensitive dictionary of headers to be sent on each
+        #: :class:`Request <Request>` sent from this
+        #: :class:`Session <Session>`.
+        self.headers = default_headers()
+
+        #: Default Authentication tuple or object to attach to
+        #: :class:`Request <Request>`.
+        self.auth = None
+
+        #: Dictionary mapping protocol to the URL of the proxy (e.g.
+        #: {'http': 'foo.bar:3128'}) to be used on each
+        #: :class:`Request <Request>`.
+        self.proxies = {}
+
+        #: Event-handling hooks.
+        self.hooks = default_hooks()
+
+        #: Dictionary of querystring data to attach to each
+        #: :class:`Request <Request>`. The dictionary values may be lists for
+        #: representing multivalued query parameters.
+        self.params = {}
+
+        #: Stream response content default.
+        self.stream = False
+
+        #: SSL Verification default.
+        self.verify = True
+
+        #: SSL certificate default.
+        self.cert = None
+
+        #: Maximum number of redirects allowed. If the request exceeds this
+        #: limit, a :class:`TooManyRedirects` exception is raised.
+        self.max_redirects = DEFAULT_REDIRECT_LIMIT
+
+        #: Should we trust the environment?
+        self.trust_env = True
+
+        # Set up a CookieJar to be used by default
+        self.cookies = cookiejar_from_dict({})
+
+        # Default connection adapters.
+        self.adapters = OrderedDict()
+        self.mount('https://', HTTPAdapter())
+        self.mount('http://', HTTPAdapter())
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.close()
+
+    def request(self, method, url,
+        params=None,
+        data=None,
+        headers=None,
+        cookies=None,
+        files=None,
+        auth=None,
+        timeout=None,
+        allow_redirects=True,
+        proxies=None,
+        hooks=None,
+        stream=None,
+        verify=None,
+        cert=None):
+        """Constructs a :class:`Request <Request>`, prepares it and sends it.
+        Returns :class:`Response <Response>` object.
+
+        :param method: method for the new :class:`Request` object.
+        :param url: URL for the new :class:`Request` object.
+        :param params: (optional) Dictionary or bytes to be sent in the query
+            string for the :class:`Request`.
+        :param data: (optional) Dictionary or bytes to send in the body of the
+            :class:`Request`.
+        :param headers: (optional) Dictionary of HTTP Headers to send with the
+            :class:`Request`.
+        :param cookies: (optional) Dict or CookieJar object to send with the
+            :class:`Request`.
+        :param files: (optional) Dictionary of 'filename': file-like-objects
+            for multipart encoding upload.
+        :param auth: (optional) Auth tuple or callable to enable
+            Basic/Digest/Custom HTTP Auth.
+        :param timeout: (optional) Float describing the timeout of the
+            request.
+        :param allow_redirects: (optional) Boolean. Set to True by default.
+        :param proxies: (optional) Dictionary mapping protocol to the URL of
+            the proxy.
+        :param stream: (optional) whether to immediately download the response
+            content. Defaults to ``False``.
+        :param verify: (optional) if ``True``, the SSL cert will be verified.
+            A CA_BUNDLE path can also be provided.
+        :param cert: (optional) if String, path to ssl client cert file (.pem).
+            If Tuple, ('cert', 'key') pair.
+        """
+
+        cookies = cookies or {}
+        proxies = proxies or {}
+
+        # Bootstrap CookieJar.
+        if not isinstance(cookies, cookielib.CookieJar):
+            cookies = cookiejar_from_dict(cookies)
+
+        # Merge with session cookies
+        merged_cookies = RequestsCookieJar()
+        merged_cookies.update(self.cookies)
+        merged_cookies.update(cookies)
+        cookies = merged_cookies
+
+        # Gather clues from the surrounding environment.
+        if self.trust_env:
+            # Set environment's proxies.
+            env_proxies = get_environ_proxies(url) or {}
+            for (k, v) in env_proxies.items():
+                proxies.setdefault(k, v)
+
+            # Set environment's basic authentication.
+            if not auth:
+                auth = get_netrc_auth(url)
+
+            # Look for configuration.
+            if not verify and verify is not False:
+                verify = os.environ.get('REQUESTS_CA_BUNDLE')
+
+            # Curl compatibility.
+            if not verify and verify is not False:
+                verify = os.environ.get('CURL_CA_BUNDLE')
+
+        # Merge all the kwargs.
+        params = merge_setting(params, self.params)
+        headers = merge_setting(headers, self.headers, dict_class=CaseInsensitiveDict)
+        auth = merge_setting(auth, self.auth)
+        proxies = merge_setting(proxies, self.proxies)
+        hooks = merge_setting(hooks, self.hooks)
+        stream = merge_setting(stream, self.stream)
+        verify = merge_setting(verify, self.verify)
+        cert = merge_setting(cert, self.cert)
+
+        # Create the Request.
+        req = Request()
+        req.method = method.upper()
+        req.url = url
+        req.headers = headers
+        req.files = files
+        req.data = data
+        req.params = params
+        req.auth = auth
+        req.cookies = cookies
+        req.hooks = hooks
+
+        # Prepare the Request.
+        prep = req.prepare()
+
+        # Send the request.
+        send_kwargs = {
+            'stream': stream,
+            'timeout': timeout,
+            'verify': verify,
+            'cert': cert,
+            'proxies': proxies,
+            'allow_redirects': allow_redirects,
+        }
+        resp = self.send(prep, **send_kwargs)
+
+        return resp
+
+    def get(self, url, **kwargs):
+        """Sends a GET request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        kwargs.setdefault('allow_redirects', True)
+        return self.request('GET', url, **kwargs)
+
+    def options(self, url, **kwargs):
+        """Sends a OPTIONS request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        kwargs.setdefault('allow_redirects', True)
+        return self.request('OPTIONS', url, **kwargs)
+
+    def head(self, url, **kwargs):
+        """Sends a HEAD request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        kwargs.setdefault('allow_redirects', False)
+        return self.request('HEAD', url, **kwargs)
+
+    def post(self, url, data=None, **kwargs):
+        """Sends a POST request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        return self.request('POST', url, data=data, **kwargs)
+
+    def put(self, url, data=None, **kwargs):
+        """Sends a PUT request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        return self.request('PUT', url, data=data, **kwargs)
+
+    def patch(self, url, data=None, **kwargs):
+        """Sends a PATCH request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        return self.request('PATCH', url,  data=data, **kwargs)
+
+    def delete(self, url, **kwargs):
+        """Sends a DELETE request. Returns :class:`Response` object.
+
+        :param url: URL for the new :class:`Request` object.
+        :param \*\*kwargs: Optional arguments that ``request`` takes.
+        """
+
+        return self.request('DELETE', url, **kwargs)
+
+    def send(self, request, **kwargs):
+        """Send a given PreparedRequest."""
+        # Set defaults that the hooks can utilize to ensure they always have
+        # the correct parameters to reproduce the previous request.
+        kwargs.setdefault('stream', self.stream)
+        kwargs.setdefault('verify', self.verify)
+        kwargs.setdefault('cert', self.cert)
+        kwargs.setdefault('proxies', self.proxies)
+
+        # It's possible that users might accidentally send a Request object.
+        # Guard against that specific failure case.
+        if getattr(request, 'prepare', None):
+            raise ValueError('You can only send PreparedRequests.')
+
+        # Set up variables needed for resolve_redirects and dispatching of
+        # hooks
+        allow_redirects = kwargs.pop('allow_redirects', True)
+        stream = kwargs.get('stream')
+        timeout = kwargs.get('timeout')
+        verify = kwargs.get('verify')
+        cert = kwargs.get('cert')
+        proxies = kwargs.get('proxies')
+        hooks = request.hooks
+
+        # Get the appropriate adapter to use
+        adapter = self.get_adapter(url=request.url)
+
+        # Start time (approximately) of the request
+        start = datetime.utcnow()
+        # Send the request
+        r = adapter.send(request, **kwargs)
+        # Total elapsed time of the request (approximately)
+        r.elapsed = datetime.utcnow() - start
+
+        # Response manipulation hooks
+        r = dispatch_hook('response', hooks, r, **kwargs)
+
+        # Persist cookies
+        extract_cookies_to_jar(self.cookies, request, r.raw)
+
+        # Redirect resolving generator.
+        gen = self.resolve_redirects(r, request, stream=stream,
+                                     timeout=timeout, verify=verify, cert=cert,
+                                     proxies=proxies)
+
+        # Resolve redirects if allowed.
+        history = [resp for resp in gen] if allow_redirects else []
+
+        # Shuffle things around if there's history.
+        if history:
+            # Insert the first (original) request at the start
+            history.insert(0, r)
+            # Get the last request made
+            r = history.pop()
+            r.history = tuple(history)
+
+        return r
+
+    def get_adapter(self, url):
+        """Returns the appropriate connnection adapter for the given URL."""
+        for (prefix, adapter) in self.adapters.items():
+
+            if url.startswith(prefix):
+                return adapter
+
+        # Nothing matches :-/
+        raise InvalidSchema("No connection adapters were found for '%s'" % url)
+
+    def close(self):
+        """Closes all adapters and as such the session"""
+        for _, v in self.adapters.items():
+            v.close()
+
+    def mount(self, prefix, adapter):
+        """Registers a connection adapter to a prefix.
+
+        Adapters are sorted in descending order by key length."""
+        self.adapters[prefix] = adapter
+        keys_to_move = [k for k in self.adapters if len(k) < len(prefix)]
+        for key in keys_to_move:
+            self.adapters[key] = self.adapters.pop(key)
+
+    def __getstate__(self):
+        return dict((attr, getattr(self, attr, None)) for attr in self.__attrs__)
+
+    def __setstate__(self, state):
+        for attr, value in state.items():
+            setattr(self, attr, value)
+
+
+def session():
+    """Returns a :class:`Session` for context-management."""
+
+    return Session()