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searxng/searx/engines/google.py
Markus Heiser 0ef6aa5126 [docs] add documentation from the sources of the google engines 
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
2021-06-21 18:25:52 +02:00

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# SPDX-License-Identifier: AGPL-3.0-or-later
# lint: pylint
"""This is the implementation of the google WEB engine. Some of this
implementations are shared by other engines:
- :ref:`google images engine`
- :ref:`google news engine`
- :ref:`google videos engine`
The google WEB engine itself has a special setup option:
.. code:: yaml
- name: google
...
use_mobile_ui: true
``use_mobile_ui``: (default: ``true``)
Enables to use *mobile endpoint* to bypass the google blocking (see
:issue:`159`). On the mobile UI of Google Search, the button :guilabel:`More
results` is not affected by Google rate limiting and we can still do requests
while actively blocked by the original Google search. By activate
``use_mobile_ui`` this behavior is simulated by adding the parameter
``async=use_ac:true,_fmt:pc`` to the :py:func:`request`.
"""
# pylint: disable=invalid-name, missing-function-docstring
from urllib.parse import urlencode
from lxml import html
from searx import logger
from searx.utils import match_language, extract_text, eval_xpath, eval_xpath_list, eval_xpath_getindex
from searx.exceptions import SearxEngineCaptchaException
logger = logger.getChild('google engine')
# about
about = {
"website": 'https://www.google.com',
"wikidata_id": 'Q9366',
"official_api_documentation": 'https://developers.google.com/custom-search/',
"use_official_api": False,
"require_api_key": False,
"results": 'HTML',
}
# engine dependent config
categories = ['general']
paging = True
time_range_support = True
safesearch = True
use_mobile_ui = False
supported_languages_url = 'https://www.google.com/preferences?#languages'
# based on https://en.wikipedia.org/wiki/List_of_Google_domains and tests
google_domains = {
'BG': 'google.bg', # Bulgaria
'CZ': 'google.cz', # Czech Republic
'DE': 'google.de', # Germany
'DK': 'google.dk', # Denmark
'AT': 'google.at', # Austria
'CH': 'google.ch', # Switzerland
'GR': 'google.gr', # Greece
'AU': 'google.com.au', # Australia
'CA': 'google.ca', # Canada
'GB': 'google.co.uk', # United Kingdom
'ID': 'google.co.id', # Indonesia
'IE': 'google.ie', # Ireland
'IN': 'google.co.in', # India
'MY': 'google.com.my', # Malaysia
'NZ': 'google.co.nz', # New Zealand
'PH': 'google.com.ph', # Philippines
'SG': 'google.com.sg', # Singapore
'US': 'google.com', # United States (google.us) redirects to .com
'ZA': 'google.co.za', # South Africa
'AR': 'google.com.ar', # Argentina
'CL': 'google.cl', # Chile
'ES': 'google.es', # Spain
'MX': 'google.com.mx', # Mexico
'EE': 'google.ee', # Estonia
'FI': 'google.fi', # Finland
'BE': 'google.be', # Belgium
'FR': 'google.fr', # France
'IL': 'google.co.il', # Israel
'HR': 'google.hr', # Croatia
'HU': 'google.hu', # Hungary
'IT': 'google.it', # Italy
'JP': 'google.co.jp', # Japan
'KR': 'google.co.kr', # South Korea
'LT': 'google.lt', # Lithuania
'LV': 'google.lv', # Latvia
'NO': 'google.no', # Norway
'NL': 'google.nl', # Netherlands
'PL': 'google.pl', # Poland
'BR': 'google.com.br', # Brazil
'PT': 'google.pt', # Portugal
'RO': 'google.ro', # Romania
'RU': 'google.ru', # Russia
'SK': 'google.sk', # Slovakia
'SI': 'google.si', # Slovenia
'SE': 'google.se', # Sweden
'TH': 'google.co.th', # Thailand
'TR': 'google.com.tr', # Turkey
'UA': 'google.com.ua', # Ukraine
'CN': 'google.com.hk', # There is no google.cn, we use .com.hk for zh-CN
'HK': 'google.com.hk', # Hong Kong
'TW': 'google.com.tw' # Taiwan
}
time_range_dict = {
'day': 'd',
'week': 'w',
'month': 'm',
'year': 'y'
}
# Filter results. 0: None, 1: Moderate, 2: Strict
filter_mapping = {
0: 'off',
1: 'medium',
2: 'high'
}
# specific xpath variables
# ------------------------
# google results are grouped into <div class="g" ../>
results_xpath = '//div[@class="g"]'
# google *sections* are no usual *results*, we ignore them
g_section_with_header = './g-section-with-header'
# the title is a h3 tag relative to the result group
title_xpath = './/h3[1]'
# in the result group there is <div class="yuRUbf" ../> it's first child is a <a
# href=...>
href_xpath = './/div[@class="yuRUbf"]//a/@href'
# in the result group there is <div class="IsZvec" ../> containing he *content*
content_xpath = './/div[@class="IsZvec"]'
# Suggestions are links placed in a *card-section*, we extract only the text
# from the links not the links itself.
suggestion_xpath = '//div[contains(@class, "card-section")]//a'
# Since google does *auto-correction* on the first query these are not really
# *spelling suggestions*, we use them anyway.
spelling_suggestion_xpath = '//div[@class="med"]/p/a'
def get_lang_info(params, lang_list, custom_aliases, supported_any_language):
"""Composing various language properties for the google engines.
This function is called by the various google engines (:ref:`google web
engine`, :ref:`google images engine`, :ref:`google news engine` and
:ref:`google videos engine`).
:param dict param: request parameters of the engine
:param list lang_list: list of supported languages of the engine
:py:obj:`ENGINES_LANGUAGES[engine-name] <searx.data.ENGINES_LANGUAGES>`
:param dict lang_list: custom aliases for non standard language codes
(used when calling :py:func:`searx.utils.match_language`)
:param bool supported_any_language: When a language is not specified, the
language interpretation is left up to Google to decide how the search
results should be delivered. This argument is ``True`` for the google
engine and ``False`` for the other engines (google-images, -news,
-scholar, -videos).
:rtype: dict
:returns:
Py-Dictionary with the key/value pairs:
language:
Return value from :py:func:`searx.utils.match_language`
country:
The country code (e.g. US, AT, CA, FR, DE ..)
subdomain:
Google subdomain :py:obj:`google_domains` that fits to the country
code.
params:
Py-Dictionary with additional request arguments (can be passed to
:py:func:`urllib.parse.urlencode`).
headers:
Py-Dictionary with additional HTTP headers (can be passed to
request's headers)
"""
ret_val = {
'language' : None,
'country' : None,
'subdomain' : None,
'params' : {},
'headers' : {},
}
# language ...
_lang = params['language']
_any_language = _lang.lower() == 'all'
if _any_language:
_lang = 'en-US'
language = match_language(_lang, lang_list, custom_aliases)
ret_val['language'] = language
# country ...
_l = _lang.split('-')
if len(_l) == 2:
country = _l[1]
else:
country = _l[0].upper()
if country == 'EN':
country = 'US'
ret_val['country'] = country
# subdomain ...
ret_val['subdomain'] = 'www.' + google_domains.get(country.upper(), 'google.com')
# params & headers
lang_country = '%s-%s' % (language, country) # (en-US, en-EN, de-DE, de-AU, fr-FR ..)
# hl parameter:
# https://developers.google.com/custom-search/docs/xml_results#hlsp The
# Interface Language:
# https://developers.google.com/custom-search/docs/xml_results_appendices#interfaceLanguages
ret_val['params']['hl'] = lang_list.get(lang_country, language)
# lr parameter:
# The lr (language restrict) parameter restricts search results to
# documents written in a particular language.
# https://developers.google.com/custom-search/docs/xml_results#lrsp
# Language Collection Values:
# https://developers.google.com/custom-search/docs/xml_results_appendices#languageCollections
if _any_language and supported_any_language:
# interpretation is left up to Google (based on whoogle)
#
# - add parameter ``source=lnt``
# - don't use parameter ``lr``
# - don't add a ``Accept-Language`` HTTP header.
ret_val['params']['source'] = 'lnt'
else:
# restricts search results to documents written in a particular
# language.
ret_val['params']['lr'] = "lang_" + lang_list.get(lang_country, language)
# Accept-Language: fr-CH, fr;q=0.8, en;q=0.6, *;q=0.5
ret_val['headers']['Accept-Language'] = ','.join([
lang_country,
language + ';q=0.8,',
'en;q=0.6',
'*;q=0.5',
])
return ret_val
def detect_google_sorry(resp):
if resp.url.host == 'sorry.google.com' or resp.url.path.startswith('/sorry'):
raise SearxEngineCaptchaException()
def request(query, params):
"""Google search request"""
offset = (params['pageno'] - 1) * 10
lang_info = get_lang_info(
# pylint: disable=undefined-variable
params, supported_languages, language_aliases, True
)
additional_parameters = {}
if use_mobile_ui:
additional_parameters = {
'async': 'use_ac:true,_fmt:pc',
}
# https://www.google.de/search?q=corona&hl=de&lr=lang_de&start=0&tbs=qdr%3Ad&safe=medium
query_url = 'https://' + lang_info['subdomain'] + '/search' + "?" + urlencode({
'q': query,
**lang_info['params'],
'ie': "utf8",
'oe': "utf8",
'start': offset,
**additional_parameters,
})
if params['time_range'] in time_range_dict:
query_url += '&' + urlencode({'tbs': 'qdr:' + time_range_dict[params['time_range']]})
if params['safesearch']:
query_url += '&' + urlencode({'safe': filter_mapping[params['safesearch']]})
params['url'] = query_url
params['headers'].update(lang_info['headers'])
if use_mobile_ui:
params['headers']['Accept'] = '*/*'
else:
params['headers']['Accept'] = (
'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8'
)
return params
def response(resp):
"""Get response from google's search request"""
detect_google_sorry(resp)
results = []
# convert the text to dom
dom = html.fromstring(resp.text)
# results --> answer
answer_list = eval_xpath(dom, '//div[contains(@class, "LGOjhe")]')
if answer_list:
answer_list = [_.xpath("normalize-space()") for _ in answer_list]
results.append({'answer': ' '.join(answer_list)})
else:
logger.debug("did not find 'answer'")
# results --> number_of_results
if not use_mobile_ui:
try:
_txt = eval_xpath_getindex(dom, '//div[@id="result-stats"]//text()', 0)
_digit = ''.join([n for n in _txt if n.isdigit()])
number_of_results = int(_digit)
results.append({'number_of_results': number_of_results})
except Exception as e: # pylint: disable=broad-except
logger.debug("did not 'number_of_results'")
logger.error(e, exc_info=True)
# parse results
for result in eval_xpath_list(dom, results_xpath):
# google *sections*
if extract_text(eval_xpath(result, g_section_with_header)):
logger.debug("ingoring <g-section-with-header>")
continue
try:
title_tag = eval_xpath_getindex(result, title_xpath, 0, default=None)
if title_tag is None:
# this not one of the common google results *section*
logger.debug('ingoring <div class="g" ../> section: missing title')
continue
title = extract_text(title_tag)
url = eval_xpath_getindex(result, href_xpath, 0, None)
if url is None:
continue
content = extract_text(eval_xpath_getindex(result, content_xpath, 0, default=None), allow_none=True)
results.append({
'url': url,
'title': title,
'content': content
})
except Exception as e: # pylint: disable=broad-except
logger.error(e, exc_info=True)
# from lxml import etree
# logger.debug(etree.tostring(result, pretty_print=True))
# import pdb
# pdb.set_trace()
continue
# parse suggestion
for suggestion in eval_xpath_list(dom, suggestion_xpath):
# append suggestion
results.append({'suggestion': extract_text(suggestion)})
for correction in eval_xpath_list(dom, spelling_suggestion_xpath):
results.append({'correction': extract_text(correction)})
# return results
return results
# get supported languages from their site
def _fetch_supported_languages(resp):
ret_val = {}
dom = html.fromstring(resp.text)
radio_buttons = eval_xpath_list(dom, '//*[@id="langSec"]//input[@name="lr"]')
for x in radio_buttons:
name = x.get("data-name")
code = x.get("value").split('_')[-1]
ret_val[code] = {"name": name}
return ret_val
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