def exit_signal(signum: 'Optional[Union[int, Signals]]' = None,
frame: 'Optional[FrameType]' = None) -> None:
"""Handler for exiting signals.
If the current process is not the main process, the function
shall transfer the signal to the main process.
Args:
signum: The signal to handle.
frame (types.FrameType): The traceback frame from the signal.
See Also:
* :func:`darc.const.getpid`
"""
from darc.process import _WORKER_POOL # pylint: disable=import-outside-toplevel
if FLAG_MP and _WORKER_POOL:
for proc in cast('List[Process]', _WORKER_POOL):
proc.kill()
proc.join()
if FLAG_TH and _WORKER_POOL:
for thrd in cast('List[Thread]', _WORKER_POOL):
thrd._stop() # type: ignore[attr-defined] # pylint: disable=protected-access
thrd.join()
if os.path.isfile(PATH_ID):
os.remove(PATH_ID)
try:
sig = strsignal(signum) if signum else signum
except Exception:
sig = signum
logger.info('[DARC] Exit with signal: %s <%s>', sig, frame)
def zeronet_bootstrap() -> None:
"""Bootstrap wrapper for ZeroNet.
The function will bootstrap the ZeroNet proxy. It will retry for
:data:`~darc.proxy.zeronet.ZERONET_RETRY` times in case of failure.
Also, it will **NOT** re-bootstrap the proxy as is guaranteed by
:data:`~darc.proxy.zeronet._ZERONET_BS_FLAG`.
Warns:
ZeroNetBootstrapFailed: If failed to bootstrap ZeroNet proxy.
Raises:
:exc:`UnsupportedPlatform`: If the system is not supported, i.e. not macOS or Linux.
See Also:
* :func:`darc.proxy.zeronet._zeronet_bootstrap`
* :data:`darc.proxy.zeronet.ZERONET_RETRY`
* :data:`darc.proxy.zeronet._ZERONET_BS_FLAG`
"""
# don't re-bootstrap
if _ZERONET_BS_FLAG:
return
logger.info('-*- ZeroNet Bootstrap -*-')
for _ in range(ZERONET_RETRY+1):
try:
_zeronet_bootstrap()
break
except Exception:
if DEBUG:
logger.ptb('[Error bootstraping ZeroNet proxy]')
logger.pexc(LOG_WARNING, category=ZeroNetBootstrapFailed, line='zeronet_bootstrap()')
logger.pline(LOG_INFO, logger.horizon)
def tor_bootstrap() -> None:
"""Bootstrap wrapper for Tor.
The function will bootstrap the Tor proxy. It will retry for
:data:`~darc.proxy.tor.TOR_RETRY` times in case of failure.
Also, it will **NOT** re-bootstrap the proxy as is guaranteed by
:data:`~darc.proxy.tor._TOR_BS_FLAG`.
Warns:
TorBootstrapFailed: If failed to bootstrap Tor proxy.
See Also:
* :func:`darc.proxy.tor._tor_bootstrap`
* :data:`darc.proxy.tor.TOR_RETRY`
* :data:`darc.proxy.tor._TOR_BS_FLAG`
"""
# don't re-bootstrap
if _TOR_BS_FLAG:
return
logger.info('-*- Tor Bootstrap -*-')
for _ in range(TOR_RETRY + 1):
try:
_tor_bootstrap()
break
except Exception:
if DEBUG:
logger.ptb('[Error bootstraping Tor proxy]')
logger.pexc(LOG_WARNING,
category=TorBootstrapFailed,
line='tor_bootstrap()')
logger.pline(LOG_INFO, logger.horizon)
def _check_ng(temp_list: 'List[darc_link.Link]') -> 'List[darc_link.Link]':
"""Check content type of links through ``HEAD`` requests.
Args:
temp_list: List of links to be checked.
Returns:
List of links matches the requirements.
See Also:
* :func:`darc.parse.match_host`
* :func:`darc.parse.match_proxy`
* :func:`darc.parse.match_mime`
"""
from darc.crawl import request_session # pylint: disable=import-outside-toplevel
session_map = {} # type: Dict[str, FuturesSession]
result_list = []
for link in temp_list:
if match_host(link.host):
continue
if match_proxy(link.proxy):
continue
# get session
session = session_map.get(link.proxy)
if session is None:
session = request_session(link, futures=True)
session_map[link.proxy] = session
result = session.head(link.url, allow_redirects=True)
result_list.append(result)
logger.info('[HEAD] Checking content type from %s', link.url)
link_list = []
for result in concurrent.futures.as_completed(result_list): # type: ignore
try:
response = result.result() # type: Response
except requests.RequestException as error:
if error.response is None:
logger.pexc(message='[HEAD] Checking failed')
continue
logger.pexc(message=f'[HEAD] Failed on {error.response.url}')
link_list.append(error.response.url)
continue
ct_type = get_content_type(response)
logger.info('[HEAD] Checked content type from %s (%s)', response.url,
ct_type)
if match_mime(ct_type):
continue
temp_link = parse_link(response.request.url) # type: ignore
link_list.append(temp_link)
return link_list
def fetch_hosts(link: 'darc_link.Link', force: bool = False) -> None:
"""Fetch ``hosts.txt``.
Args:
link: Link object to fetch for its ``hosts.txt``.
force: Force refetch ``hosts.txt``.
Returns:
Content of the ``hosts.txt`` file.
"""
if force:
logger.warning('[HOSTS] Force refetch %s', link.url)
hosts_path = None if force else have_hosts(link)
if hosts_path is not None:
logger.warning('[HOSTS] Cached %s', link.url) # pylint: disable=no-member
with open(hosts_path) as hosts_file:
hosts_text = hosts_file.read()
else:
from darc.requests import i2p_session # pylint: disable=import-outside-toplevel
hosts_link = parse_link(urljoin(link.url, '/hosts.txt'), backref=link)
logger.info('[HOSTS] Subscribing %s', hosts_link.url)
with i2p_session() as session:
try:
response = session.get(hosts_link.url)
except requests.RequestException:
logger.pexc(message=f'[HOSTS] Failed on {hosts_link.url}')
return
if not response.ok:
logger.error('[HOSTS] Failed on %s [%d]', hosts_link.url, response.status_code)
return
ct_type = get_content_type(response)
if ct_type not in ['text/text', 'text/plain']:
logger.error('[HOSTS] Unresolved content type on %s (%s)', hosts_link.url, ct_type)
return
hosts_text = response.text
save_hosts(hosts_link, hosts_text)
logger.info('[HOSTS] Subscribed %s', hosts_link.url)
from darc.db import save_requests # pylint: disable=import-outside-toplevel
# add link to queue
save_requests(read_hosts(link, hosts_text))
def process_crawler() -> None:
"""A worker to run the :func:`~darc.crawl.crawler` process.
Warns:
HookExecutionFailed: When hook function raises an error.
"""
logger.info('[CRAWLER] Starting mainloop...')
logger.debug('[CRAWLER] Starting first round...')
# start mainloop
while True:
# requests crawler
link_pool = load_requests()
if not link_pool:
if DARC_WAIT is not None:
time.sleep(DARC_WAIT)
continue
for link in link_pool:
crawler(link)
time2break = False
for hook in _HOOK_REGISTRY:
try:
hook('crawler', link_pool)
except WorkerBreak:
time2break = True
except Exception:
logger.pexc(LOG_WARNING, '[CRAWLER] hook execution failed',
HookExecutionFailed)
# marked to break by hook function
if time2break:
break
# quit in reboot mode
if REBOOT:
break
# renew Tor session
renew_tor_session()
logger.debug('[CRAWLER] Starting next round...')
logger.info('[CRAWLER] Stopping mainloop...')
def freenet_bootstrap() -> None:
"""Bootstrap wrapper for Freenet.
The function will bootstrap the Freenet proxy. It will retry for
:data:`~darc.proxy.freenet.FREENET_RETRY` times in case of failure.
Also, it will **NOT** re-bootstrap the proxy as is guaranteed by
:data:`~darc.proxy.freenet._FREENET_BS_FLAG`.
Warns:
FreenetBootstrapFailed: If failed to bootstrap Freenet proxy.
Raises:
:exc:`UnsupportedPlatform`: If the system is not supported, i.e. not macOS or Linux.
See Also:
* :func:`darc.proxy.freenet._freenet_bootstrap`
* :data:`darc.proxy.freenet.FREENET_RETRY`
* :data:`darc.proxy.freenet._FREENET_BS_FLAG`
"""
if _unsupported:
raise UnsupportedPlatform(f'unsupported system: {platform.system()}')
# don't re-bootstrap
if _FREENET_BS_FLAG:
return
logger.info('-*- Freenet Bootstrap -*-')
for _ in range(FREENET_RETRY + 1):
try:
_freenet_bootstrap()
break
except Exception:
if DEBUG:
logger.ptb('[Error bootstraping Freenet proxy]')
logger.pexc(LOG_WARNING,
category=FreenetBootstrapFailed,
line='freenet_bootstrap()')
logger.pline(LOG_INFO, logger.horizon)
def fetch_sitemap(link: 'darc_link.Link', force: bool = False) -> None:
"""Fetch sitemap.
The function will first fetch the ``robots.txt``, then
fetch the sitemaps accordingly.
Args:
link: Link object to fetch for its sitemaps.
force: Force refetch its sitemaps.
Returns:
Contents of ``robots.txt`` and sitemaps.
See Also:
* :func:`darc.proxy.null.read_robots`
* :func:`darc.proxy.null.read_sitemap`
* :func:`darc.parse.get_sitemap`
"""
if force:
logger.warning('[ROBOTS] Force refetch %s', link.url)
robots_path = None if force else have_robots(link)
if robots_path is not None:
logger.warning('[ROBOTS] Cached %s', link.url)
with open(robots_path) as file:
robots_text = file.read()
else:
robots_link = parse_link(urljoin(link.url, '/robots.txt'), backref=link)
logger.info('[ROBOTS] Checking %s', robots_link.url)
with request_session(robots_link) as session:
try:
response = session.get(robots_link.url)
except requests.RequestException:
logger.pexc(message=f'[ROBOTS] Failed on {robots_link.url}')
return
if response.ok:
ct_type = get_content_type(response)
if ct_type not in ['text/text', 'text/plain']:
logger.error('[ROBOTS] Unresolved content type on %s (%s)', robots_link.url, ct_type)
robots_text = ''
else:
robots_text = response.text
save_robots(robots_link, robots_text)
logger.info('[ROBOTS] Checked %s', robots_link.url)
else:
logger.error('[ROBOTS] Failed on %s [%d]', robots_link.url, response.status_code)
robots_text = ''
if force:
logger.warning('[SITEMAP] Force refetch %s', link.url)
sitemaps = read_robots(link, robots_text, host=link.host)
for sitemap_link in sitemaps:
sitemap_path = None if force else have_sitemap(sitemap_link)
if sitemap_path is not None:
logger.warning('[SITEMAP] Cached %s', sitemap_link.url)
with open(sitemap_path) as file:
sitemap_text = file.read()
else:
logger.info('[SITEMAP] Fetching %s', sitemap_link.url)
with request_session(sitemap_link) as session:
try:
response = session.get(sitemap_link.url)
except requests.RequestException:
logger.pexc(message=f'[SITEMAP] Failed on {sitemap_link.url}')
continue
if not response.ok:
logger.error('[SITEMAP] Failed on %s [%d]', sitemap_link.url, response.status_code)
continue
# check content type
ct_type = get_content_type(response)
if ct_type == 'application/gzip':
try:
sitemap_text = gzip.decompress(response.content).decode()
except UnicodeDecodeError:
sitemap_text = response.text
elif ct_type in ['text/xml', 'text/html']:
sitemap_text = response.text
save_sitemap(sitemap_link, sitemap_text)
else:
logger.error('[SITEMAP] Unresolved content type on %s (%s)', sitemap_link.url, ct_type)
continue
logger.info('[SITEMAP] Fetched %s', sitemap_link.url)
# get more sitemaps
sitemaps.extend(get_sitemap(sitemap_link, sitemap_text, host=link.host))
# add link to queue
save_requests(read_sitemap(link, sitemap_text))
os.kill(pid, signum)
return
if isinstance(signum, enum.Enum):
sigint = signum.value
else:
sigint = signum
for func in _HANDLER_REGISTRY[sigint]:
func(signum, frame)
try:
sig = strsignal(signum) if signum else signum
except Exception:
sig = f'Signal: {signum}'
logger.info('[DARC] Handled signal: %s <%s>', sig, frame)
def exit_signal(signum: 'Optional[Union[int, Signals]]' = None,
frame: 'Optional[FrameType]' = None) -> None:
"""Handler for exiting signals.
If the current process is not the main process, the function
shall transfer the signal to the main process.
Args:
signum: The signal to handle.
frame (types.FrameType): The traceback frame from the signal.
See Also:
* :func:`darc.const.getpid`
def process(worker: 'Literal["crawler", "loader"]') -> None:
"""Main process.
The function will register :func:`~darc.process._signal_handler` for ``SIGTERM``,
and start the main process of the :mod:`darc` darkweb crawlers.
Args:
worker: Worker process type.
Raises:
ValueError: If ``worker`` is not a valid value.
Before starting the workers, the function will start proxies through
* :func:`darc.proxy.tor.tor_proxy`
* :func:`darc.proxy.i2p.i2p_proxy`
* :func:`darc.proxy.zeronet.zeronet_proxy`
* :func:`darc.proxy.freenet.freenet_proxy`
The general process can be described as following for *workers* of ``crawler`` type:
1. :func:`~darc.process.process_crawler`: obtain URLs from the :mod:`requests`
link database (c.f. :func:`~darc.db.load_requests`), and feed such URLs to
:func:`~darc.crawl.crawler`.
.. note::
If :data:`~darc.const.FLAG_MP` is :data:`True`, the function will be
called with *multiprocessing* support; if :data:`~darc.const.FLAG_TH`
if :data:`True`, the function will be called with *multithreading*
support; if none, the function will be called in single-threading.
2. :func:`~darc.crawl.crawler`: parse the URL using
:func:`~darc.link.parse_link`, and check if need to crawl the
URL (c.f. :data:`~darc.const.PROXY_WHITE_LIST`, :data:`~darc.const.PROXY_BLACK_LIST`
, :data:`~darc.const.LINK_WHITE_LIST` and :data:`~darc.const.LINK_BLACK_LIST`);
if true, then crawl the URL with :mod:`requests`.
If the URL is from a brand new host, :mod:`darc` will first try
to fetch and save ``robots.txt`` and sitemaps of the host
(c.f. :func:`~darc.proxy.null.save_robots` and :func:`~darc.proxy.null.save_sitemap`),
and extract then save the links from sitemaps (c.f. :func:`~darc.proxy.null.read_sitemap`)
into link database for future crawling (c.f. :func:`~darc.db.save_requests`).
Also, if the submission API is provided, :func:`~darc.submit.submit_new_host`
will be called and submit the documents just fetched.
If ``robots.txt`` presented, and :data:`~darc.const.FORCE` is
:data:`False`, :mod:`darc` will check if allowed to crawl the URL.
.. note::
The root path (e.g. ``/`` in https://www.example.com/) will always
be crawled ignoring ``robots.txt``.
At this point, :mod:`darc` will call the customised hook function
from :mod:`darc.sites` to crawl and get the final response object.
:mod:`darc` will save the session cookies and header information,
using :func:`~darc.save.save_headers`.
.. note::
If :exc:`requests.exceptions.InvalidSchema` is raised, the link
will be saved by :func:`~darc.proxy.null.save_invalid`. Further
processing is dropped.
If the content type of response document is not ignored (c.f.
:data:`~darc.const.MIME_WHITE_LIST` and :data:`~darc.const.MIME_BLACK_LIST`),
:func:`~darc.submit.submit_requests` will be called and submit the document
just fetched.
If the response document is HTML (``text/html`` and ``application/xhtml+xml``),
:func:`~darc.parse.extract_links` will be called then to extract all possible
links from the HTML document and save such links into the database
(c.f. :func:`~darc.db.save_requests`).
And if the response status code is between ``400`` and ``600``,
the URL will be saved back to the link database
(c.f. :func:`~darc.db.save_requests`). If **NOT**, the URL will
be saved into :mod:`selenium` link database to proceed next steps
(c.f. :func:`~darc.db.save_selenium`).
The general process can be described as following for *workers* of ``loader`` type:
1. :func:`~darc.process.process_loader`: in the meanwhile, :mod:`darc` will
obtain URLs from the :mod:`selenium` link database (c.f. :func:`~darc.db.load_selenium`),
and feed such URLs to :func:`~darc.crawl.loader`.
.. note::
If :data:`~darc.const.FLAG_MP` is :data:`True`, the function will be
called with *multiprocessing* support; if :data:`~darc.const.FLAG_TH`
if :data:`True`, the function will be called with *multithreading*
support; if none, the function will be called in single-threading.
2. :func:`~darc.crawl.loader`: parse the URL using
:func:`~darc.link.parse_link` and start loading the URL using
:mod:`selenium` with Google Chrome.
At this point, :mod:`darc` will call the customised hook function
from :mod:`darc.sites` to load and return the original
:class:`~selenium.webdriver.Chrome` object.
If successful, the rendered source HTML document will be saved, and a
full-page screenshot will be taken and saved.
If the submission API is provided, :func:`~darc.submit.submit_selenium`
will be called and submit the document just loaded.
Later, :func:`~darc.parse.extract_links` will be called then to
extract all possible links from the HTML document and save such
links into the :mod:`requests` database (c.f. :func:`~darc.db.save_requests`).
After each *round*, :mod:`darc` will call registered hook functions in
sequential order, with the type of worker (``'crawler'`` or ``'loader'``)
and the current link pool as its parameters, see :func:`~darc.process.register`
for more information.
If in reboot mode, i.e. :data:`~darc.const.REBOOT` is :data:`True`, the function
will exit after first round. If not, it will renew the Tor connections (if
bootstrapped), c.f. :func:`~darc.proxy.tor.renew_tor_session`, and start
another round.
"""
register_signal(signal.SIGINT, exit_signal)
register_signal(signal.SIGTERM, exit_signal)
#register_signal(signal.SIGKILL, exit_signal)
logger.info('[DARC] Starting %s...', worker)
if not _TOR_BS_FLAG:
tor_bootstrap()
if not _I2P_BS_FLAG:
i2p_bootstrap()
if not _ZERONET_BS_FLAG:
zeronet_bootstrap()
if not _FREENET_BS_FLAG:
freenet_bootstrap()
if worker == 'crawler':
_process(process_crawler)
elif worker == 'loader':
_process(process_loader)
else:
raise ValueError(f'invalid worker type: {worker!r}')
logger.info('[DARC] Gracefully existing %s...', worker)
def crawler(link: 'darc_link.Link') -> None:
"""Single :mod:`requests` crawler for an entry link.
Args:
link: URL to be crawled by :mod:`requests`.
The function will first parse the URL using
:func:`~darc.link.parse_link`, and check if need to crawl the
URL (c.f. :data:`~darc.const.PROXY_WHITE_LIST`, :data:`~darc.const.PROXY_BLACK_LIST`,
:data:`~darc.const.LINK_WHITE_LIST` and :data:`~darc.const.LINK_BLACK_LIST`);
if true, then crawl the URL with :mod:`requests`.
If the URL is from a brand new host, :mod:`darc` will first try
to fetch and save ``robots.txt`` and sitemaps of the host
(c.f. :func:`~darc.proxy.null.save_robots` and :func:`~darc.proxy.null.save_sitemap`),
and extract then save the links from sitemaps (c.f. :func:`~darc.proxy.null.read_sitemap`)
into link database for future crawling (c.f. :func:`~darc.db.save_requests`).
.. note::
A host is new if :func:`~darc.db.have_hostname` returns :data:`True`.
If :func:`darc.proxy.null.fetch_sitemap` and/or :func:`darc.proxy.i2p.fetch_hosts`
failed when fetching such documents, the host will be removed from the
hostname database through :func:`~darc.db.drop_hostname`, and considered
as new when next encounter.
Also, if the submission API is provided, :func:`~darc.submit.submit_new_host`
will be called and submit the documents just fetched.
If ``robots.txt`` presented, and :data:`~darc.const.FORCE` is
:data:`False`, :mod:`darc` will check if allowed to crawl the URL.
.. note::
The root path (e.g. ``/`` in https://www.example.com/) will always
be crawled ignoring ``robots.txt``.
At this point, :mod:`darc` will call the customised hook function
from :mod:`darc.sites` to crawl and get the final response object.
:mod:`darc` will save the session cookies and header information,
using :func:`~darc.save.save_headers`.
.. note::
If :exc:`requests.exceptions.InvalidSchema` is raised, the link
will be saved by :func:`~darc.proxy.null.save_invalid`. Further
processing is dropped, and the link will be removed from the
:mod:`requests` database through :func:`~darc.db.drop_requests`.
If :exc:`~darc.error.LinkNoReturn` is raised, the link will be
removed from the :mod:`requests` database through
:func:`~darc.db.drop_requests`.
If the content type of response document is not ignored (c.f.
:data:`~darc.const.MIME_WHITE_LIST` and :data:`~darc.const.MIME_BLACK_LIST`),
:func:`~darc.submit.submit_requests` will be called and submit the document
just fetched.
If the response document is HTML (``text/html`` and ``application/xhtml+xml``),
:func:`~darc.parse.extract_links` will be called then to extract
all possible links from the HTML document and save such links into
the database (c.f. :func:`~darc.db.save_requests`).
And if the response status code is between ``400`` and ``600``,
the URL will be saved back to the link database
(c.f. :func:`~darc.db.save_requests`). If **NOT**, the URL will
be saved into :mod:`selenium` link database to proceed next steps
(c.f. :func:`~darc.db.save_selenium`).
"""
logger.info('[REQUESTS] Requesting %s', link.url)
try:
if match_proxy(link.proxy):
logger.warning('[REQUESTS] Ignored proxy type from %s (%s)',
link.url, link.proxy)
drop_requests(link)
return
if match_host(link.host):
logger.warning('[REQUESTS] Ignored hostname from %s (%s)',
link.url, link.proxy)
drop_requests(link)
return
# timestamp
timestamp = datetime.now()
# get the session object in advance
session = request_session(link)
# check whether schema supported by :mod:`requests`
try:
session.get_adapter(link.url) # test for adapter
requests_supported = True
except requests.exceptions.InvalidSchema:
requests_supported = False
# if need to test for new host
if requests_supported:
# if it's a new host
flag_have, force_fetch = have_hostname(link)
if not flag_have or force_fetch:
partial = False
if link.proxy not in ('zeronet', 'freenet'):
# fetch sitemap.xml
try:
fetch_sitemap(link, force=force_fetch)
except Exception:
logger.ptb('[Error fetching sitemap of %s]', link.url)
partial = True
if link.proxy == 'i2p':
# fetch hosts.txt
try:
fetch_hosts(link, force=force_fetch)
except Exception:
logger.ptb('[Error subscribing hosts from %s]',
link.url)
partial = True
# submit data / drop hostname from db
if partial:
drop_hostname(link)
submit_new_host(timestamp,
link,
partial=partial,
force=force_fetch)
if not FORCE and not check_robots(link):
logger.warning('[REQUESTS] Robots disallowed link from %s',
link.url)
return
# reuse the session object
with session:
try:
# requests session hook
response = crawler_hook(timestamp, session, link)
except requests.exceptions.InvalidSchema:
logger.pexc(message=f'[REQUESTS] Fail to crawl {link.url}')
save_invalid(link)
drop_requests(link)
return
except requests.RequestException as error:
logger.pexc(message=f'[REQUESTS] Fail to crawl {link.url}')
save_requests(link, single=True)
return
except LinkNoReturn as error:
logger.pexc(LOG_WARNING,
f'[REQUESTS] Removing from database: {link.url}')
if error.drop:
drop_requests(link)
return
# save headers
save_headers(timestamp, link, response, session)
# check content type
ct_type = get_content_type(response)
if ct_type not in ['text/html', 'application/xhtml+xml']:
logger.warning('[REQUESTS] Generic content type from %s (%s)',
link.url, ct_type)
# probably hosts.txt
if link.proxy == 'i2p' and ct_type in [
'text/plain', 'text/text'
]:
text = response.text
save_requests(read_hosts(link, text))
if match_mime(ct_type):
drop_requests(link)
return
# submit data
data = response.content
submit_requests(timestamp,
link,
response,
session,
data,
mime_type=ct_type,
html=False)
return
html = response.content
if not html:
logger.error('[REQUESTS] Empty response from %s', link.url)
save_requests(link, single=True)
return
# submit data
submit_requests(timestamp,
link,
response,
session,
html,
mime_type=ct_type,
html=True)
# add link to queue
save_requests(extract_links(link, html), score=0, nx=True)
if not response.ok:
logger.error('[REQUESTS] Failed on %s [%d]', link.url,
response.status_code)
save_requests(link, single=True)
return
# add link to queue
save_selenium(link, single=True, score=0, nx=True)
except Exception:
if SAVE_DB:
with contextlib.suppress(Exception):
host = HostnameModel.get_or_none(
HostnameModel.hostname ==
link.host) # type: Optional[HostnameModel]
if host is not None:
host.alive = False
host.save()
with contextlib.suppress(Exception):
url = URLModel.get_or_none(
URLModel.hash == link.name) # type: Optional[URLModel]
if url is not None:
url.alias = False
url.save()
logger.ptb('[Error from %s]', link.url)
save_requests(link, single=True)
logger.info('[REQUESTS] Requested %s', link.url)
def loader(link: 'darc_link.Link') -> None:
"""Single :mod:`selenium` loader for an entry link.
Args:
Link: URL to be crawled by :mod:`selenium`.
The function will first parse the URL using :func:`~darc.link.parse_link`
and start loading the URL using :mod:`selenium` with Google Chrome.
At this point, :mod:`darc` will call the customised hook function
from :mod:`darc.sites` to load and return the original
:class:`selenium.webdriver.chrome.webdriver.WebDriver` object.
.. note::
If :exc:`~darc.error.LinkNoReturn` is raised, the link will be
removed from the :mod:`selenium` database through
:func:`~darc.db.drop_selenium`.
If successful, the rendered source HTML document will be saved, and a
full-page screenshot will be taken and saved.
.. note::
When taking full-page screenshot, :func:`~darc.crawl.loader` will
use :javascript:`document.body.scrollHeight` to get the total
height of web page. If the page height is *less than* **1,000 pixels**,
then :mod:`darc` will by default set the height as **1,000 pixels**.
Later :mod:`darc` will tell :mod:`selenium` to resize the window (in
*headless* mode) to **1,024 pixels** in width and **110%** of the
page height in height, and take a *PNG* screenshot.
If the submission API is provided, :func:`~darc.submit.submit_selenium`
will be called and submit the document just loaded.
Later, :func:`~darc.parse.extract_links` will be called then to
extract all possible links from the HTML document and save such
links into the :mod:`requests` database (c.f. :func:`~darc.db.save_requests`).
.. seealso::
* :data:`darc.const.SE_EMPTY`
* :data:`darc.const.SE_WAIT`
"""
logger.info('[SELENIUM] Loading %s', link.url)
try:
# timestamp
timestamp = datetime.now()
# retrieve source from Chrome
with request_driver(link) as driver:
try:
# selenium driver hook
driver = loader_hook(timestamp, driver, link)
except urllib3_exceptions.HTTPError:
logger.pexc(message=f'[SELENIUM] Fail to load {link.url}')
save_selenium(link, single=True)
return
except selenium_exceptions.WebDriverException as error:
logger.pexc(message=f'[SELENIUM] Fail to load {link.url}')
save_selenium(link, single=True)
return
except LinkNoReturn as error:
logger.pexc(LOG_WARNING,
f'[SELENIUM] Removing from database: {link.url}')
if error.drop:
drop_selenium(link)
return
# get HTML source
html = driver.page_source
if html == SE_EMPTY:
logger.error('[SELENIUM] Empty page from %s', link.url)
save_selenium(link, single=True)
return
screenshot = None
try:
# get maximum height
height = driver.execute_script(
'return document.body.scrollHeight')
# resize window (with some magic numbers)
driver.set_window_size(1024,
math.ceil(max(height, 1000) * 1.1))
# take a full page screenshot
screenshot = driver.get_screenshot_as_base64()
except Exception:
logger.pexc(
message=
f'[SELENIUM] Fail to save screenshot from {link.url}')
# submit data
submit_selenium(timestamp, link, html, screenshot)
# add link to queue
save_requests(extract_links(link, html), score=0, nx=True)
except Exception:
logger.ptb('[Error from %s]', link.url)
save_selenium(link, single=True)
logger.info('[SELENIUM] Loaded %s', link.url)
