497 lines
20 KiB
Python
497 lines
20 KiB
Python
"""Blocking and non-blocking HTTP client interfaces.
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This module defines a common interface shared by two implementations,
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``simple_httpclient`` and ``curl_httpclient``. Applications may either
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instantiate their chosen implementation class directly or use the
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`AsyncHTTPClient` class from this module, which selects an implementation
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that can be overridden with the `AsyncHTTPClient.configure` method.
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The default implementation is ``simple_httpclient``, and this is expected
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to be suitable for most users' needs. However, some applications may wish
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to switch to ``curl_httpclient`` for reasons such as the following:
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* ``curl_httpclient`` has some features not found in ``simple_httpclient``,
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including support for HTTP proxies and the ability to use a specified
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network interface.
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* ``curl_httpclient`` is more likely to be compatible with sites that are
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not-quite-compliant with the HTTP spec, or sites that use little-exercised
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features of HTTP.
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* ``curl_httpclient`` is faster.
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* ``curl_httpclient`` was the default prior to Tornado 2.0.
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Note that if you are using ``curl_httpclient``, it is highly recommended that
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you use a recent version of ``libcurl`` and ``pycurl``. Currently the minimum
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supported version is 7.18.2, and the recommended version is 7.21.1 or newer.
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"""
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from __future__ import absolute_import, division, print_function, with_statement
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import functools
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import time
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import weakref
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from tornado.concurrent import Future
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from tornado.escape import utf8
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from tornado import httputil, stack_context
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from tornado.ioloop import IOLoop
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from tornado.util import Configurable
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class HTTPClient(object):
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"""A blocking HTTP client.
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This interface is provided for convenience and testing; most applications
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that are running an IOLoop will want to use `AsyncHTTPClient` instead.
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Typical usage looks like this::
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http_client = httpclient.HTTPClient()
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try:
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response = http_client.fetch("http://www.google.com/")
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print response.body
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except httpclient.HTTPError as e:
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print "Error:", e
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http_client.close()
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"""
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def __init__(self, async_client_class=None, **kwargs):
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self._io_loop = IOLoop()
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if async_client_class is None:
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async_client_class = AsyncHTTPClient
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self._async_client = async_client_class(self._io_loop, **kwargs)
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self._closed = False
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def __del__(self):
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self.close()
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def close(self):
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"""Closes the HTTPClient, freeing any resources used."""
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if not self._closed:
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self._async_client.close()
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self._io_loop.close()
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self._closed = True
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def fetch(self, request, **kwargs):
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"""Executes a request, returning an `HTTPResponse`.
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The request may be either a string URL or an `HTTPRequest` object.
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If it is a string, we construct an `HTTPRequest` using any additional
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kwargs: ``HTTPRequest(request, **kwargs)``
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If an error occurs during the fetch, we raise an `HTTPError`.
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"""
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response = self._io_loop.run_sync(functools.partial(
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self._async_client.fetch, request, **kwargs))
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response.rethrow()
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return response
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class AsyncHTTPClient(Configurable):
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"""An non-blocking HTTP client.
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Example usage::
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def handle_request(response):
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if response.error:
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print "Error:", response.error
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else:
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print response.body
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http_client = AsyncHTTPClient()
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http_client.fetch("http://www.google.com/", handle_request)
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The constructor for this class is magic in several respects: It
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actually creates an instance of an implementation-specific
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subclass, and instances are reused as a kind of pseudo-singleton
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(one per `.IOLoop`). The keyword argument ``force_instance=True``
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can be used to suppress this singleton behavior. Constructor
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arguments other than ``io_loop`` and ``force_instance`` are
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deprecated. The implementation subclass as well as arguments to
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its constructor can be set with the static method `configure()`
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"""
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@classmethod
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def configurable_base(cls):
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return AsyncHTTPClient
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@classmethod
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def configurable_default(cls):
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from tornado.simple_httpclient import SimpleAsyncHTTPClient
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return SimpleAsyncHTTPClient
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@classmethod
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def _async_clients(cls):
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attr_name = '_async_client_dict_' + cls.__name__
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if not hasattr(cls, attr_name):
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setattr(cls, attr_name, weakref.WeakKeyDictionary())
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return getattr(cls, attr_name)
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def __new__(cls, io_loop=None, force_instance=False, **kwargs):
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io_loop = io_loop or IOLoop.current()
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if io_loop in cls._async_clients() and not force_instance:
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return cls._async_clients()[io_loop]
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instance = super(AsyncHTTPClient, cls).__new__(cls, io_loop=io_loop,
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**kwargs)
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if not force_instance:
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cls._async_clients()[io_loop] = instance
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return instance
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def initialize(self, io_loop, defaults=None):
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self.io_loop = io_loop
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self.defaults = dict(HTTPRequest._DEFAULTS)
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if defaults is not None:
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self.defaults.update(defaults)
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def close(self):
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"""Destroys this HTTP client, freeing any file descriptors used.
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Not needed in normal use, but may be helpful in unittests that
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create and destroy http clients. No other methods may be called
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on the `AsyncHTTPClient` after ``close()``.
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"""
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if self._async_clients().get(self.io_loop) is self:
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del self._async_clients()[self.io_loop]
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def fetch(self, request, callback=None, **kwargs):
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"""Executes a request, asynchronously returning an `HTTPResponse`.
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The request may be either a string URL or an `HTTPRequest` object.
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If it is a string, we construct an `HTTPRequest` using any additional
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kwargs: ``HTTPRequest(request, **kwargs)``
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This method returns a `.Future` whose result is an
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`HTTPResponse`. The ``Future`` wil raise an `HTTPError` if
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the request returned a non-200 response code.
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If a ``callback`` is given, it will be invoked with the `HTTPResponse`.
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In the callback interface, `HTTPError` is not automatically raised.
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Instead, you must check the response's ``error`` attribute or
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call its `~HTTPResponse.rethrow` method.
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"""
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if not isinstance(request, HTTPRequest):
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request = HTTPRequest(url=request, **kwargs)
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# We may modify this (to add Host, Accept-Encoding, etc),
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# so make sure we don't modify the caller's object. This is also
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# where normal dicts get converted to HTTPHeaders objects.
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request.headers = httputil.HTTPHeaders(request.headers)
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request = _RequestProxy(request, self.defaults)
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future = Future()
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if callback is not None:
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callback = stack_context.wrap(callback)
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def handle_future(future):
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exc = future.exception()
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if isinstance(exc, HTTPError) and exc.response is not None:
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response = exc.response
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elif exc is not None:
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response = HTTPResponse(
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request, 599, error=exc,
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request_time=time.time() - request.start_time)
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else:
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response = future.result()
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self.io_loop.add_callback(callback, response)
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future.add_done_callback(handle_future)
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def handle_response(response):
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if response.error:
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future.set_exception(response.error)
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else:
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future.set_result(response)
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self.fetch_impl(request, handle_response)
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return future
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def fetch_impl(self, request, callback):
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raise NotImplementedError()
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@classmethod
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def configure(cls, impl, **kwargs):
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"""Configures the `AsyncHTTPClient` subclass to use.
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``AsyncHTTPClient()`` actually creates an instance of a subclass.
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This method may be called with either a class object or the
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fully-qualified name of such a class (or ``None`` to use the default,
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``SimpleAsyncHTTPClient``)
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If additional keyword arguments are given, they will be passed
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to the constructor of each subclass instance created. The
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keyword argument ``max_clients`` determines the maximum number
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of simultaneous `~AsyncHTTPClient.fetch()` operations that can
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execute in parallel on each `.IOLoop`. Additional arguments
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may be supported depending on the implementation class in use.
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Example::
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AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
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"""
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super(AsyncHTTPClient, cls).configure(impl, **kwargs)
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class HTTPRequest(object):
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"""HTTP client request object."""
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# Default values for HTTPRequest parameters.
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# Merged with the values on the request object by AsyncHTTPClient
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# implementations.
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_DEFAULTS = dict(
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connect_timeout=20.0,
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request_timeout=20.0,
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follow_redirects=True,
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max_redirects=5,
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use_gzip=True,
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proxy_password='',
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allow_nonstandard_methods=False,
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validate_cert=True)
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def __init__(self, url, method="GET", headers=None, body=None,
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auth_username=None, auth_password=None, auth_mode=None,
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connect_timeout=None, request_timeout=None,
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if_modified_since=None, follow_redirects=None,
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max_redirects=None, user_agent=None, use_gzip=None,
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network_interface=None, streaming_callback=None,
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header_callback=None, prepare_curl_callback=None,
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proxy_host=None, proxy_port=None, proxy_username=None,
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proxy_password=None, allow_nonstandard_methods=None,
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validate_cert=None, ca_certs=None,
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allow_ipv6=None,
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client_key=None, client_cert=None):
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r"""All parameters except ``url`` are optional.
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:arg string url: URL to fetch
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:arg string method: HTTP method, e.g. "GET" or "POST"
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:arg headers: Additional HTTP headers to pass on the request
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:arg body: HTTP body to pass on the request
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:type headers: `~tornado.httputil.HTTPHeaders` or `dict`
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:arg string auth_username: Username for HTTP authentication
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:arg string auth_password: Password for HTTP authentication
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:arg string auth_mode: Authentication mode; default is "basic".
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Allowed values are implementation-defined; ``curl_httpclient``
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supports "basic" and "digest"; ``simple_httpclient`` only supports
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"basic"
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:arg float connect_timeout: Timeout for initial connection in seconds
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:arg float request_timeout: Timeout for entire request in seconds
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:arg if_modified_since: Timestamp for ``If-Modified-Since`` header
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:type if_modified_since: `datetime` or `float`
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:arg bool follow_redirects: Should redirects be followed automatically
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or return the 3xx response?
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:arg int max_redirects: Limit for ``follow_redirects``
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:arg string user_agent: String to send as ``User-Agent`` header
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:arg bool use_gzip: Request gzip encoding from the server
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:arg string network_interface: Network interface to use for request
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:arg callable streaming_callback: If set, ``streaming_callback`` will
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be run with each chunk of data as it is received, and
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``HTTPResponse.body`` and ``HTTPResponse.buffer`` will be empty in
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the final response.
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:arg callable header_callback: If set, ``header_callback`` will
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be run with each header line as it is received (including the
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first line, e.g. ``HTTP/1.0 200 OK\r\n``, and a final line
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containing only ``\r\n``. All lines include the trailing newline
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characters). ``HTTPResponse.headers`` will be empty in the final
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response. This is most useful in conjunction with
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``streaming_callback``, because it's the only way to get access to
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header data while the request is in progress.
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:arg callable prepare_curl_callback: If set, will be called with
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a ``pycurl.Curl`` object to allow the application to make additional
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``setopt`` calls.
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:arg string proxy_host: HTTP proxy hostname. To use proxies,
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``proxy_host`` and ``proxy_port`` must be set; ``proxy_username`` and
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``proxy_pass`` are optional. Proxies are currently only supported
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with ``curl_httpclient``.
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:arg int proxy_port: HTTP proxy port
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:arg string proxy_username: HTTP proxy username
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:arg string proxy_password: HTTP proxy password
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:arg bool allow_nonstandard_methods: Allow unknown values for ``method``
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argument?
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:arg bool validate_cert: For HTTPS requests, validate the server's
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certificate?
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:arg string ca_certs: filename of CA certificates in PEM format,
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or None to use defaults. Note that in ``curl_httpclient``, if
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any request uses a custom ``ca_certs`` file, they all must (they
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don't have to all use the same ``ca_certs``, but it's not possible
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to mix requests with ``ca_certs`` and requests that use the defaults.
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:arg bool allow_ipv6: Use IPv6 when available? Default is false in
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``simple_httpclient`` and true in ``curl_httpclient``
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:arg string client_key: Filename for client SSL key, if any
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:arg string client_cert: Filename for client SSL certificate, if any
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.. versionadded:: 3.1
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The ``auth_mode`` argument.
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"""
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if headers is None:
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headers = httputil.HTTPHeaders()
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if if_modified_since:
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headers["If-Modified-Since"] = httputil.format_timestamp(
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if_modified_since)
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self.proxy_host = proxy_host
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self.proxy_port = proxy_port
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self.proxy_username = proxy_username
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self.proxy_password = proxy_password
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self.url = url
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self.method = method
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self.headers = headers
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self.body = utf8(body)
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self.auth_username = auth_username
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self.auth_password = auth_password
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self.auth_mode = auth_mode
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self.connect_timeout = connect_timeout
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self.request_timeout = request_timeout
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self.follow_redirects = follow_redirects
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self.max_redirects = max_redirects
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self.user_agent = user_agent
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self.use_gzip = use_gzip
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self.network_interface = network_interface
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self.streaming_callback = stack_context.wrap(streaming_callback)
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self.header_callback = stack_context.wrap(header_callback)
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self.prepare_curl_callback = stack_context.wrap(prepare_curl_callback)
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self.allow_nonstandard_methods = allow_nonstandard_methods
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self.validate_cert = validate_cert
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self.ca_certs = ca_certs
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self.allow_ipv6 = allow_ipv6
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self.client_key = client_key
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self.client_cert = client_cert
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self.start_time = time.time()
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class HTTPResponse(object):
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"""HTTP Response object.
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Attributes:
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* request: HTTPRequest object
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* code: numeric HTTP status code, e.g. 200 or 404
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* reason: human-readable reason phrase describing the status code
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(with curl_httpclient, this is a default value rather than the
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server's actual response)
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* headers: `tornado.httputil.HTTPHeaders` object
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* buffer: ``cStringIO`` object for response body
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* body: response body as string (created on demand from ``self.buffer``)
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* error: Exception object, if any
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* request_time: seconds from request start to finish
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* time_info: dictionary of diagnostic timing information from the request.
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Available data are subject to change, but currently uses timings
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available from http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html,
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plus ``queue``, which is the delay (if any) introduced by waiting for
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a slot under `AsyncHTTPClient`'s ``max_clients`` setting.
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"""
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def __init__(self, request, code, headers=None, buffer=None,
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effective_url=None, error=None, request_time=None,
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time_info=None, reason=None):
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if isinstance(request, _RequestProxy):
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self.request = request.request
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else:
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self.request = request
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self.code = code
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self.reason = reason or httputil.responses.get(code, "Unknown")
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if headers is not None:
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self.headers = headers
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else:
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self.headers = httputil.HTTPHeaders()
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self.buffer = buffer
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self._body = None
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if effective_url is None:
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self.effective_url = request.url
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else:
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self.effective_url = effective_url
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if error is None:
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if self.code < 200 or self.code >= 300:
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self.error = HTTPError(self.code, response=self)
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else:
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self.error = None
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else:
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self.error = error
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self.request_time = request_time
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self.time_info = time_info or {}
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def _get_body(self):
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if self.buffer is None:
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return None
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elif self._body is None:
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self._body = self.buffer.getvalue()
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return self._body
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body = property(_get_body)
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def rethrow(self):
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"""If there was an error on the request, raise an `HTTPError`."""
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if self.error:
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raise self.error
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def __repr__(self):
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args = ",".join("%s=%r" % i for i in sorted(self.__dict__.items()))
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return "%s(%s)" % (self.__class__.__name__, args)
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class HTTPError(Exception):
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"""Exception thrown for an unsuccessful HTTP request.
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Attributes:
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* ``code`` - HTTP error integer error code, e.g. 404. Error code 599 is
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used when no HTTP response was received, e.g. for a timeout.
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* ``response`` - `HTTPResponse` object, if any.
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Note that if ``follow_redirects`` is False, redirects become HTTPErrors,
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and you can look at ``error.response.headers['Location']`` to see the
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destination of the redirect.
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"""
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def __init__(self, code, message=None, response=None):
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self.code = code
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message = message or httputil.responses.get(code, "Unknown")
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self.response = response
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Exception.__init__(self, "HTTP %d: %s" % (self.code, message))
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class _RequestProxy(object):
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"""Combines an object with a dictionary of defaults.
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Used internally by AsyncHTTPClient implementations.
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"""
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def __init__(self, request, defaults):
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self.request = request
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self.defaults = defaults
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def __getattr__(self, name):
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request_attr = getattr(self.request, name)
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if request_attr is not None:
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return request_attr
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elif self.defaults is not None:
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return self.defaults.get(name, None)
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else:
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return None
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def main():
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from tornado.options import define, options, parse_command_line
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define("print_headers", type=bool, default=False)
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define("print_body", type=bool, default=True)
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define("follow_redirects", type=bool, default=True)
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define("validate_cert", type=bool, default=True)
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args = parse_command_line()
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client = HTTPClient()
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for arg in args:
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try:
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response = client.fetch(arg,
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follow_redirects=options.follow_redirects,
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validate_cert=options.validate_cert,
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)
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except HTTPError as e:
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if e.response is not None:
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response = e.response
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else:
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raise
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if options.print_headers:
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print(response.headers)
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if options.print_body:
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print(response.body)
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client.close()
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if __name__ == "__main__":
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|
main()
|