python-telegram-bot/telegram/utils/request.py

#!/usr/bin/env python
#
# A library that provides a Python interface to the Telegram Bot API
# Copyright (C) 2015-2017
# Leandro Toledo de Souza <devs@python-telegram-bot.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser Public License for more details.
#
# You should have received a copy of the GNU Lesser Public License
# along with this program.  If not, see [http://www.gnu.org/licenses/].
"""This module contains methods to make POST and GET requests"""
import os
import socket
import logging

try:
    import ujson as json
except ImportError:
    import json

import certifi
import urllib3
import urllib3.contrib.appengine
from urllib3.connection import HTTPConnection
from urllib3.util.timeout import Timeout

from telegram import (InputFile, TelegramError)
from telegram.error import (Unauthorized, NetworkError, TimedOut, BadRequest, ChatMigrated,
                            RetryAfter, InvalidToken)

logging.getLogger('urllib3').setLevel(logging.WARNING)


class Request(object):
    """
    Helper class for python-telegram-bot which provides methods to perform POST & GET towards
    telegram servers.

    Args:
        con_pool_size (int): Number of connections to keep in the connection pool.
        proxy_url (str): The URL to the proxy server. For example: `http://127.0.0.1:3128`.
        urllib3_proxy_kwargs (dict): Arbitrary arguments passed as-is to `urllib3.ProxyManager`.
            This value will be ignored if proxy_url is not set.
        connect_timeout (int|float): The maximum amount of time (in seconds) to wait for a
            connection attempt to a server to succeed. None will set an infinite timeout for
            connection attempts. (default: 5.)
        read_timeout (int|float): The maximum amount of time (in seconds) to wait between
            consecutive read operations for a response from the server. None will set an infinite
            timeout. This value is usually overridden by the various ``telegram.Bot`` methods.
            (default: 5.)

    """

    def __init__(self,
                 con_pool_size=1,
                 proxy_url=None,
                 urllib3_proxy_kwargs=None,
                 connect_timeout=5.,
                 read_timeout=5.):
        if urllib3_proxy_kwargs is None:
            urllib3_proxy_kwargs = dict()

        self._connect_timeout = connect_timeout

        kwargs = dict(
            maxsize=con_pool_size,
            cert_reqs='CERT_REQUIRED',
            ca_certs=certifi.where(),
            socket_options=HTTPConnection.default_socket_options + [
                (socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),
            ],
            timeout=urllib3.Timeout(
                connect=self._connect_timeout, read=read_timeout, total=None))

        # Set a proxy according to the following order:
        # * proxy defined in proxy_url (+ urllib3_proxy_kwargs)
        # * proxy set in `HTTPS_PROXY` env. var.
        # * proxy set in `https_proxy` env. var.
        # * None (if no proxy is configured)

        if not proxy_url:
            proxy_url = os.environ.get('HTTPS_PROXY') or os.environ.get('https_proxy')

        if not proxy_url:
            if urllib3.contrib.appengine.is_appengine_sandbox():
                # Use URLFetch service if running in App Engine
                mgr = urllib3.contrib.appengine.AppEngineManager()
            else:
                mgr = urllib3.PoolManager(**kwargs)
        else:
            kwargs.update(urllib3_proxy_kwargs)
            if proxy_url.startswith('socks'):
                try:
                    from urllib3.contrib.socks import SOCKSProxyManager
                except ImportError:
                    raise RuntimeError('PySocks is missing')
                mgr = SOCKSProxyManager(proxy_url, **kwargs)
            else:
                mgr = urllib3.proxy_from_url(proxy_url, **kwargs)
                if mgr.proxy.auth:
                    # TODO: what about other auth types?
                    auth_hdrs = urllib3.make_headers(proxy_basic_auth=mgr.proxy.auth)
                    mgr.proxy_headers.update(auth_hdrs)

        self._con_pool = mgr

    def stop(self):
        self._con_pool.clear()

    @staticmethod
    def _parse(json_data):
        """Try and parse the JSON returned from Telegram.

        Returns:
            dict: A JSON parsed as Python dict with results - on error this dict will be empty.

        """
        decoded_s = json_data.decode('utf-8')
        try:
            data = json.loads(decoded_s)
        except ValueError:
            raise TelegramError('Invalid server response')

        if not data.get('ok'):
            description = data.get('description')
            parameters = data.get('parameters')
            if parameters:
                migrate_to_chat_id = parameters.get('migrate_to_chat_id')
                if migrate_to_chat_id:
                    raise ChatMigrated(migrate_to_chat_id)
                retry_after = parameters.get('retry_after')
                if retry_after:
                    raise RetryAfter(retry_after)
            if description:
                return description

        return data['result']

    def _request_wrapper(self, *args, **kwargs):
        """Wraps urllib3 request for handling known exceptions.

        Args:
            args: unnamed arguments, passed to urllib3 request.
            kwargs: keyword arguments, passed tp urllib3 request.

        Returns:
            str: A non-parsed JSON text.

        Raises:
            TelegramError

        """
        # Make sure to hint Telegram servers that we reuse connections by sending
        # "Connection: keep-alive" in the HTTP headers.
        if 'headers' not in kwargs:
            kwargs['headers'] = {}
        kwargs['headers']['connection'] = 'keep-alive'

        try:
            resp = self._con_pool.request(*args, **kwargs)
        except urllib3.exceptions.TimeoutError:
            raise TimedOut()
        except urllib3.exceptions.HTTPError as error:
            # HTTPError must come last as its the base urllib3 exception class
            # TODO: do something smart here; for now just raise NetworkError
            raise NetworkError('urllib3 HTTPError {0}'.format(error))

        if 200 <= resp.status <= 299:
            # 200-299 range are HTTP success statuses
            return resp.data

        try:
            message = self._parse(resp.data)
        except ValueError:
            raise NetworkError('Unknown HTTPError {0}'.format(resp.status))

        if resp.status in (401, 403):
            raise Unauthorized(message)
        elif resp.status == 400:
            raise BadRequest(message)
        elif resp.status == 404:
            raise InvalidToken()
        elif resp.status == 502:
            raise NetworkError('Bad Gateway')
        else:
            raise NetworkError('{0} ({1})'.format(message, resp.status))

    def get(self, url, timeout=None):
        """Request an URL.

        Args:
            url (str): The web location we want to retrieve.
            timeout (Optional[int|float]): If this value is specified, use it as the read timeout
                from the server (instead of the one specified during creation of the connection
                pool).

        Returns:
          A JSON object.

        """
        urlopen_kwargs = {}

        if timeout is not None:
            urlopen_kwargs['timeout'] = Timeout(read=timeout, connect=self._connect_timeout)

        result = self._request_wrapper('GET', url, **urlopen_kwargs)
        return self._parse(result)

    def post(self, url, data, timeout=None):
        """Request an URL.
        Args:
            url (str): The web location we want to retrieve.
            data (dict[str, str]): A dict of key/value pairs. Note: On py2.7 value is unicode.
            timeout (Optional[int|float]): If this value is specified, use it as the read timeout
                from the server (instead of the one specified during creation of the connection
                pool).

        Returns:
          A JSON object.

        """
        urlopen_kwargs = {}

        if timeout is not None:
            urlopen_kwargs['timeout'] = Timeout(read=timeout, connect=self._connect_timeout)

        if InputFile.is_inputfile(data):
            data = InputFile(data)
            result = self._request_wrapper(
                'POST', url, body=data.to_form(), headers=data.headers, **urlopen_kwargs)
        else:
            data = json.dumps(data)
            result = self._request_wrapper(
                'POST',
                url,
                body=data.encode(),
                headers={'Content-Type': 'application/json'},
                **urlopen_kwargs)

        return self._parse(result)

    def retrieve(self, url, timeout=None):
        """Retrieve the contents of a file by its URL.

        Args:
            url (str): The web location we want to retrieve.
            timeout (Optional[int|float]): If this value is specified, use it as the read timeout
                from the server (instead of the one specified during creation of the connection
                pool).

        """
        urlopen_kwargs = {}
        if timeout is not None:
            urlopen_kwargs['timeout'] = Timeout(read=timeout, connect=self._connect_timeout)

        return self._request_wrapper('GET', url, **urlopen_kwargs)

    def download(self, url, filename, timeout=None):
        """Download a file by its URL.
        Args:
            url (str): The web location we want to retrieve.
            timeout (Optional[int|float]): If this value is specified, use it as the read timeout
                from the server (instead of the one specified during creation of the connection
                pool).

          filename:
            The filename within the path to download the file.

        """
        buf = self.retrieve(url, timeout=timeout)
        with open(filename, 'wb') as fobj:
            fobj.write(buf)