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searxng/searx/engines/duckduckgo.py
Markus Heiser 14323d683f [fix] ddg-lite & ddg-extra: don't send empty vqd value
DDG's bot detection is sensitive to the vqd value.  For some search terms (such
as extremely long search terms that are often sent by bots), no vqd value can be
determined.

If SearXNG cannot determine a vqd value, then no request should go out to
DDG (WEB): a request with a wrong vqd value leads to DDG temporarily putting
SearXNG's IP on a block list.

Requests from IPs in this block list run into timeouts.

Not sure, but it seems the block list is a sliding window: to get my IP rid from
the bot list I had to cool down my IP for 1h (send no requests from that IP to
DDG).

Since such issues can't reproduce in a local instance I tested this patch 24h on
my public SearXNG instance: There are still errors (rare), but the reliability
is still 100%.

Related:

- https://github.com/searxng/searxng/pull/2922
- https://github.com/searxng/searxng/pull/2923

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
2023-10-12 08:52:28 +02:00

468 lines
14 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-or-later
# lint: pylint
"""
DuckDuckGo Lite
~~~~~~~~~~~~~~~
"""
from typing import TYPE_CHECKING
import re
from urllib.parse import urlencode
import json
import babel
import lxml.html
from searx import (
locales,
redislib,
external_bang,
)
from searx.utils import (
eval_xpath,
eval_xpath_getindex,
extract_text,
)
from searx.network import get # see https://github.com/searxng/searxng/issues/762
from searx import redisdb
from searx.enginelib.traits import EngineTraits
if TYPE_CHECKING:
import logging
logger: logging.Logger
traits: EngineTraits
about = {
"website": 'https://lite.duckduckgo.com/lite/',
"wikidata_id": 'Q12805',
"use_official_api": False,
"require_api_key": False,
"results": 'HTML',
}
send_accept_language_header = True
"""DuckDuckGo-Lite tries to guess user's prefered language from the HTTP
``Accept-Language``. Optional the user can select a region filter (but not a
language).
"""
# engine dependent config
categories = ['general', 'web']
paging = True
time_range_support = True
safesearch = True # user can't select but the results are filtered
url = 'https://lite.duckduckgo.com/lite/'
# url_ping = 'https://duckduckgo.com/t/sl_l'
time_range_dict = {'day': 'd', 'week': 'w', 'month': 'm', 'year': 'y'}
form_data = {'v': 'l', 'api': 'd.js', 'o': 'json'}
def cache_vqd(query, value):
"""Caches a ``vqd`` value from a query."""
c = redisdb.client()
if c:
logger.debug("cache vqd value: %s", value)
key = 'SearXNG_ddg_vqd' + redislib.secret_hash(query)
c.set(key, value, ex=600)
def get_vqd(query):
"""Returns the ``vqd`` that fits to the *query*. If there is no ``vqd`` cached
(:py:obj:`cache_vqd`) the query is sent to DDG to get a vqd value from the
response.
.. hint::
If an empty string is returned there are no results for the ``query`` and
therefore no ``vqd`` value.
DDG's bot detection is sensitive to the ``vqd`` value. For some search terms
(such as extremely long search terms that are often sent by bots), no ``vqd``
value can be determined.
If SearXNG cannot determine a ``vqd`` value, then no request should go out
to DDG:
A request with a wrong ``vqd`` value leads to DDG temporarily putting
SearXNG's IP on a block list.
Requests from IPs in this block list run into timeouts.
Not sure, but it seems the block list is a sliding window: to get my IP rid
from the bot list I had to cool down my IP for 1h (send no requests from
that IP to DDG).
TL;DR; the ``vqd`` value is needed to pass DDG's bot protection and is used
by all request to DDG:
- DuckDuckGo Lite: ``https://lite.duckduckgo.com/lite`` (POST form data)
- DuckDuckGo Web: ``https://links.duckduckgo.com/d.js?q=...&vqd=...``
- DuckDuckGo Images: ``https://duckduckgo.com/i.js??q=...&vqd=...``
- DuckDuckGo Videos: ``https://duckduckgo.com/v.js??q=...&vqd=...``
- DuckDuckGo News: ``https://duckduckgo.com/news.js??q=...&vqd=...``
"""
value = ''
c = redisdb.client()
if c:
key = 'SearXNG_ddg_vqd' + redislib.secret_hash(query)
value = c.get(key)
if value or value == b'':
value = value.decode('utf-8')
logger.debug("re-use cached vqd value: %s", value)
return value
query_url = 'https://lite.duckduckgo.com/lite/?{args}'.format(args=urlencode({'q': query}))
res = get(query_url)
doc = lxml.html.fromstring(res.text)
value = doc.xpath("//input[@name='vqd']/@value")
if value:
value = value[0]
else:
# Some search terms do not have results and therefore no vqd value. If
# no vqd value can be determined for the search term, an empty string is
# chached.
value = ''
logger.debug("new vqd value: '%s'", value)
cache_vqd(query, value)
return value
def get_ddg_lang(eng_traits: EngineTraits, sxng_locale, default='en_US'):
"""Get DuckDuckGo's language identifier from SearXNG's locale.
DuckDuckGo defines its languages by region codes (see
:py:obj:`fetch_traits`).
To get region and language of a DDG service use:
.. code: python
eng_region = traits.get_region(params['searxng_locale'], traits.all_locale)
eng_lang = get_ddg_lang(traits, params['searxng_locale'])
It might confuse, but the ``l`` value of the cookie is what SearXNG calls
the *region*:
.. code:: python
# !ddi paris :es-AR --> {'ad': 'es_AR', 'ah': 'ar-es', 'l': 'ar-es'}
params['cookies']['ad'] = eng_lang
params['cookies']['ah'] = eng_region
params['cookies']['l'] = eng_region
.. hint::
`DDG-lite <https://lite.duckduckgo.com/lite>`__ does not offer a language
selection to the user, only a region can be selected by the user
(``eng_region`` from the example above). DDG-lite stores the selected
region in a cookie::
params['cookies']['kl'] = eng_region # 'ar-es'
"""
return eng_traits.custom['lang_region'].get( # type: ignore
sxng_locale, eng_traits.get_language(sxng_locale, default)
)
ddg_reg_map = {
'tw-tzh': 'zh_TW',
'hk-tzh': 'zh_HK',
'ct-ca': 'skip', # ct-ca and es-ca both map to ca_ES
'es-ca': 'ca_ES',
'id-en': 'id_ID',
'no-no': 'nb_NO',
'jp-jp': 'ja_JP',
'kr-kr': 'ko_KR',
'xa-ar': 'ar_SA',
'sl-sl': 'sl_SI',
'th-en': 'th_TH',
'vn-en': 'vi_VN',
}
ddg_lang_map = {
# use ar --> ar_EG (Egypt's arabic)
"ar_DZ": 'lang_region',
"ar_JO": 'lang_region',
"ar_SA": 'lang_region',
# use bn --> bn_BD
'bn_IN': 'lang_region',
# use de --> de_DE
'de_CH': 'lang_region',
# use en --> en_US,
'en_AU': 'lang_region',
'en_CA': 'lang_region',
'en_GB': 'lang_region',
# Esperanto
'eo_XX': 'eo',
# use es --> es_ES,
'es_AR': 'lang_region',
'es_CL': 'lang_region',
'es_CO': 'lang_region',
'es_CR': 'lang_region',
'es_EC': 'lang_region',
'es_MX': 'lang_region',
'es_PE': 'lang_region',
'es_UY': 'lang_region',
'es_VE': 'lang_region',
# use fr --> rf_FR
'fr_CA': 'lang_region',
'fr_CH': 'lang_region',
'fr_BE': 'lang_region',
# use nl --> nl_NL
'nl_BE': 'lang_region',
# use pt --> pt_PT
'pt_BR': 'lang_region',
# skip these languages
'od_IN': 'skip',
'io_XX': 'skip',
'tokipona_XX': 'skip',
}
def request(query, params):
# request needs a vqd argument
vqd = get_vqd(query)
if not vqd:
# some search terms do not have results and therefore no vqd value
params['url'] = None
return params
# quote ddg bangs
query_parts = []
# for val in re.split(r'(\s+)', query):
for val in re.split(r'(\s+)', query):
if not val.strip():
continue
if val.startswith('!') and external_bang.get_node(external_bang.EXTERNAL_BANGS, val[1:]):
val = f"'{val}'"
query_parts.append(val)
query = ' '.join(query_parts)
eng_region = traits.get_region(params['searxng_locale'], traits.all_locale)
# eng_lang = get_ddg_lang(traits, params['searxng_locale'])
params['url'] = url
params['method'] = 'POST'
params['data']['q'] = query
# The API is not documented, so we do some reverse engineering and emulate
# what https://lite.duckduckgo.com/lite/ does when you press "next Page"
# link again and again ..
params['headers']['Content-Type'] = 'application/x-www-form-urlencoded'
params['data']['vqd'] = vqd
# initial page does not have an offset
if params['pageno'] == 2:
# second page does have an offset of 30
offset = (params['pageno'] - 1) * 30
params['data']['s'] = offset
params['data']['dc'] = offset + 1
elif params['pageno'] > 2:
# third and following pages do have an offset of 30 + n*50
offset = 30 + (params['pageno'] - 2) * 50
params['data']['s'] = offset
params['data']['dc'] = offset + 1
# initial page does not have additional data in the input form
if params['pageno'] > 1:
params['data']['o'] = form_data.get('o', 'json')
params['data']['api'] = form_data.get('api', 'd.js')
params['data']['nextParams'] = form_data.get('nextParams', '')
params['data']['v'] = form_data.get('v', 'l')
params['headers']['Referer'] = 'https://lite.duckduckgo.com/'
params['data']['kl'] = eng_region
params['cookies']['kl'] = eng_region
params['data']['df'] = ''
if params['time_range'] in time_range_dict:
params['data']['df'] = time_range_dict[params['time_range']]
params['cookies']['df'] = time_range_dict[params['time_range']]
logger.debug("param data: %s", params['data'])
logger.debug("param cookies: %s", params['cookies'])
return params
def response(resp):
if resp.status_code == 303:
return []
results = []
doc = lxml.html.fromstring(resp.text)
result_table = eval_xpath(doc, '//html/body/form/div[@class="filters"]/table')
if len(result_table) == 2:
# some locales (at least China) does not have a "next page" button and
# the layout of the HTML tables is different.
result_table = result_table[1]
elif not len(result_table) >= 3:
# no more results
return []
else:
result_table = result_table[2]
# update form data from response
form = eval_xpath(doc, '//html/body/form/div[@class="filters"]/table//input/..')
if len(form):
form = form[0]
form_data['v'] = eval_xpath(form, '//input[@name="v"]/@value')[0]
form_data['api'] = eval_xpath(form, '//input[@name="api"]/@value')[0]
form_data['o'] = eval_xpath(form, '//input[@name="o"]/@value')[0]
logger.debug('form_data: %s', form_data)
value = eval_xpath(form, '//input[@name="vqd"]/@value')[0]
query = resp.search_params['data']['q']
cache_vqd(query, value)
tr_rows = eval_xpath(result_table, './/tr')
# In the last <tr> is the form of the 'previous/next page' links
tr_rows = tr_rows[:-1]
len_tr_rows = len(tr_rows)
offset = 0
while len_tr_rows >= offset + 4:
# assemble table rows we need to scrap
tr_title = tr_rows[offset]
tr_content = tr_rows[offset + 1]
offset += 4
# ignore sponsored Adds <tr class="result-sponsored">
if tr_content.get('class') == 'result-sponsored':
continue
a_tag = eval_xpath_getindex(tr_title, './/td//a[@class="result-link"]', 0, None)
if a_tag is None:
continue
td_content = eval_xpath_getindex(tr_content, './/td[@class="result-snippet"]', 0, None)
if td_content is None:
continue
results.append(
{
'title': a_tag.text_content(),
'content': extract_text(td_content),
'url': a_tag.get('href'),
}
)
return results
def fetch_traits(engine_traits: EngineTraits):
"""Fetch languages & regions from DuckDuckGo.
SearXNG's ``all`` locale maps DuckDuckGo's "Alle regions" (``wt-wt``).
DuckDuckGo's language "Browsers prefered language" (``wt_WT``) makes no
sense in a SearXNG request since SearXNG's ``all`` will not add a
``Accept-Language`` HTTP header. The value in ``engine_traits.all_locale``
is ``wt-wt`` (the region).
Beside regions DuckDuckGo also defines its languages by region codes. By
example these are the english languages in DuckDuckGo:
- en_US
- en_AU
- en_CA
- en_GB
The function :py:obj:`get_ddg_lang` evaluates DuckDuckGo's language from
SearXNG's locale.
"""
# pylint: disable=too-many-branches, too-many-statements
# fetch regions
engine_traits.all_locale = 'wt-wt'
# updated from u588 to u661 / should be updated automatically?
resp = get('https://duckduckgo.com/util/u661.js')
if not resp.ok: # type: ignore
print("ERROR: response from DuckDuckGo is not OK.")
pos = resp.text.find('regions:{') + 8 # type: ignore
js_code = resp.text[pos:] # type: ignore
pos = js_code.find('}') + 1
regions = json.loads(js_code[:pos])
for eng_tag, name in regions.items():
if eng_tag == 'wt-wt':
engine_traits.all_locale = 'wt-wt'
continue
region = ddg_reg_map.get(eng_tag)
if region == 'skip':
continue
if not region:
eng_territory, eng_lang = eng_tag.split('-')
region = eng_lang + '_' + eng_territory.upper()
try:
sxng_tag = locales.region_tag(babel.Locale.parse(region))
except babel.UnknownLocaleError:
print("ERROR: %s (%s) -> %s is unknown by babel" % (name, eng_tag, region))
continue
conflict = engine_traits.regions.get(sxng_tag)
if conflict:
if conflict != eng_tag:
print("CONFLICT: babel %s --> %s, %s" % (sxng_tag, conflict, eng_tag))
continue
engine_traits.regions[sxng_tag] = eng_tag
# fetch languages
engine_traits.custom['lang_region'] = {}
pos = resp.text.find('languages:{') + 10 # type: ignore
js_code = resp.text[pos:] # type: ignore
pos = js_code.find('}') + 1
js_code = '{"' + js_code[1:pos].replace(':', '":').replace(',', ',"')
languages = json.loads(js_code)
for eng_lang, name in languages.items():
if eng_lang == 'wt_WT':
continue
babel_tag = ddg_lang_map.get(eng_lang, eng_lang)
if babel_tag == 'skip':
continue
try:
if babel_tag == 'lang_region':
sxng_tag = locales.region_tag(babel.Locale.parse(eng_lang))
engine_traits.custom['lang_region'][sxng_tag] = eng_lang
continue
sxng_tag = locales.language_tag(babel.Locale.parse(babel_tag))
except babel.UnknownLocaleError:
print("ERROR: language %s (%s) is unknown by babel" % (name, eng_lang))
continue
conflict = engine_traits.languages.get(sxng_tag)
if conflict:
if conflict != eng_lang:
print("CONFLICT: babel %s --> %s, %s" % (sxng_tag, conflict, eng_lang))
continue
engine_traits.languages[sxng_tag] = eng_lang