import asyncio import re from pathlib import PurePath from typing import Any, Awaitable, Callable, Dict, List, Optional, Set, TypeVar, Union import aiohttp from aiohttp import hdrs from bs4 import BeautifulSoup, Tag from ...auth import Authenticator, TfaAuthenticator from ...config import Config from ...logging import ProgressBar, log from ...output_dir import FileSink, Redownload from ...utils import fmt_path, soupify, url_set_query_param from ..crawler import CrawlError, CrawlToken, CrawlWarning, DownloadToken, anoncritical from ..http_crawler import HttpCrawler, HttpCrawlerSection from .file_templates import Links from .kit_ilias_html import IliasElementType, IliasPage, IliasPageElement TargetType = Union[str, int] class KitIliasWebCrawlerSection(HttpCrawlerSection): def target(self) -> TargetType: target = self.s.get("target") if not target: self.missing_value("target") if re.fullmatch(r"\d+", target): # Course id return int(target) if target == "desktop": # Full personal desktop return target if target.startswith("https://ilias.studium.kit.edu"): # ILIAS URL return target self.invalid_value("target", target, "Should be ") def tfa_auth(self, authenticators: Dict[str, Authenticator]) -> Optional[Authenticator]: value: Optional[str] = self.s.get("tfa_auth") if value is None: return None auth = authenticators.get(value) if auth is None: self.invalid_value("tfa_auth", value, "No such auth section exists") return auth def links(self) -> Links: type_str: Optional[str] = self.s.get("links") if type_str is None: return Links.FANCY try: return Links.from_string(type_str) except ValueError as e: self.invalid_value("links", type_str, str(e).capitalize()) def link_redirect_delay(self) -> int: return self.s.getint("link_redirect_delay", fallback=-1) def videos(self) -> bool: return self.s.getboolean("videos", fallback=False) _DIRECTORY_PAGES: Set[IliasElementType] = set([ IliasElementType.EXERCISE, IliasElementType.EXERCISE_FILES, IliasElementType.FOLDER, IliasElementType.MEETING, IliasElementType.VIDEO_FOLDER, IliasElementType.VIDEO_FOLDER_MAYBE_PAGINATED, ]) _VIDEO_ELEMENTS: Set[IliasElementType] = set([ IliasElementType.VIDEO, IliasElementType.VIDEO_PLAYER, IliasElementType.VIDEO_FOLDER, IliasElementType.VIDEO_FOLDER_MAYBE_PAGINATED, ]) AWrapped = TypeVar("AWrapped", bound=Callable[..., Awaitable[Optional[Any]]]) def _iorepeat(attempts: int, name: str) -> Callable[[AWrapped], AWrapped]: def decorator(f: AWrapped) -> AWrapped: async def wrapper(*args: Any, **kwargs: Any) -> Optional[Any]: last_exception: Optional[BaseException] = None for round in range(attempts): try: return await f(*args, **kwargs) except aiohttp.ContentTypeError: # invalid content type raise CrawlWarning("ILIAS returned an invalid content type") except aiohttp.TooManyRedirects: raise CrawlWarning("Got stuck in a redirect loop") except aiohttp.ClientPayloadError as e: # encoding or not enough bytes last_exception = e except aiohttp.ClientConnectionError as e: # e.g. timeout, disconnect, resolve failed, etc. last_exception = e except asyncio.exceptions.TimeoutError as e: # explicit http timeouts in HttpCrawler last_exception = e log.explain_topic(f"Retrying operation {name}. Retries left: {attempts - 1 - round}") if last_exception: message = f"Error in I/O Operation: {last_exception}" raise CrawlWarning(message) from last_exception raise CrawlError("Impossible return in ilias _iorepeat") return wrapper # type: ignore return decorator def _wrap_io_in_warning(name: str) -> Callable[[AWrapped], AWrapped]: """ Wraps any I/O exception in a CrawlWarning. """ return _iorepeat(1, name) # Crawler control flow: # # crawl_desktop -+ # | # crawl_course --+ # | # @_io_repeat | # retries internally (before the bar) # +- crawl_url <-+ # | # | # | @_wrap_io_exception # does not need to retry as children acquire bars # +> crawl_ilias_element -+ # ^ | # | @_io_repeat | # retries internally (before the bar) # +- crawl_ilias_page <---+ # | | # +> get_page | # Handles and retries authentication # | # @_io_repeat | # retries internally (before the bar) # +- download_link <---+ # | | # +> resolve_target | # Handles and retries authentication # | # @_io_repeat | # retries internally (before the bar) # +- download_video <---+ # | | # | @_io_repeat | # retries internally (before the bar) # +- download_file <---+ # | # +> stream_from_url # Handles and retries authentication class KitIliasWebCrawler(HttpCrawler): def __init__( self, name: str, section: KitIliasWebCrawlerSection, config: Config, authenticators: Dict[str, Authenticator] ): # Setting a main authenticator for cookie sharing auth = section.auth(authenticators) super().__init__(name, section, config, shared_auth=auth) if section.tasks() > 1: log.warn(""" Please avoid using too many parallel requests as these are the KIT ILIAS instance's greatest bottleneck. """.strip()) self._shibboleth_login = KitShibbolethLogin( auth, section.tfa_auth(authenticators), ) self._base_url = "https://ilias.studium.kit.edu" self._target = section.target() self._link_file_redirect_delay = section.link_redirect_delay() self._links = section.links() self._videos = section.videos() async def _run(self) -> None: if isinstance(self._target, int): log.explain_topic(f"Inferred crawl target: Course with id {self._target}") await self._crawl_course(self._target) elif self._target == "desktop": log.explain_topic("Inferred crawl target: Personal desktop") await self._crawl_desktop() else: log.explain_topic(f"Inferred crawl target: URL {self._target}") await self._crawl_url(self._target) async def _crawl_course(self, course_id: int) -> None: # Start crawling at the given course root_url = url_set_query_param( self._base_url + "/goto.php", "target", f"crs_{course_id}" ) await self._crawl_url(root_url, expected_id=course_id) async def _crawl_desktop(self) -> None: await self._crawl_url(self._base_url) async def _crawl_url(self, url: str, expected_id: Optional[int] = None) -> None: maybe_cl = await self.crawl(PurePath(".")) if not maybe_cl: return cl = maybe_cl # Not mypy's fault, but explained here: https://github.com/python/mypy/issues/2608 elements: List[IliasPageElement] = [] @_iorepeat(3, "crawling url") async def gather_elements() -> None: elements.clear() async with cl: soup = await self._get_page(url) if expected_id is not None: perma_link_element: Tag = soup.find(id="current_perma_link") if not perma_link_element or "crs_" not in perma_link_element.get("value"): raise CrawlError("Invalid course id? Didn't find anything looking like a course") # Duplicated code, but the root page is special - we want to avoid fetching it twice! log.explain_topic("Parsing root HTML page") log.explain(f"URL: {url}") page = IliasPage(soup, url, None) elements.extend(page.get_child_elements()) # Fill up our task list with the found elements await gather_elements() elements.sort(key=lambda e: e.id()) tasks: List[Awaitable[None]] = [] for element in elements: if handle := await self._handle_ilias_element(PurePath("."), element): tasks.append(asyncio.create_task(handle)) # And execute them await self.gather(tasks) async def _handle_ilias_page( self, url: str, parent: IliasPageElement, path: PurePath, ) -> Optional[Awaitable[None]]: maybe_cl = await self.crawl(path) if not maybe_cl: return None return self._crawl_ilias_page(url, parent, maybe_cl) async def _crawl_ilias_page( self, url: str, parent: IliasPageElement, cl: CrawlToken, ) -> None: elements: List[IliasPageElement] = [] @_iorepeat(3, "crawling folder") async def gather_elements() -> None: elements.clear() async with cl: next_stage_url: Optional[str] = url current_parent = parent while next_stage_url: soup = await self._get_page(next_stage_url) log.explain_topic(f"Parsing HTML page for {fmt_path(cl.path)}") log.explain(f"URL: {next_stage_url}") page = IliasPage(soup, next_stage_url, current_parent) if next_element := page.get_next_stage_element(): current_parent = next_element next_stage_url = next_element.url else: next_stage_url = None elements.extend(page.get_child_elements()) # Fill up our task list with the found elements await gather_elements() elements.sort(key=lambda e: e.id()) tasks: List[Awaitable[None]] = [] for element in elements: if handle := await self._handle_ilias_element(cl.path, element): tasks.append(asyncio.create_task(handle)) # And execute them await self.gather(tasks) @anoncritical # Shouldn't happen but we also really don't want to let I/O errors bubble up to anoncritical. # If that happens we will be terminated as anoncritical doesn't tream them as non-critical. @_wrap_io_in_warning("handling ilias element") async def _handle_ilias_element( self, parent_path: PurePath, element: IliasPageElement, ) -> Optional[Awaitable[None]]: element_path = PurePath(parent_path, element.name) if element.type in _VIDEO_ELEMENTS: log.explain_topic(f"Decision: Crawl video element {fmt_path(element_path)}") if not self._videos: log.explain("Video crawling is disabled") log.explain("Answer: no") return None else: log.explain("Video crawling is enabled") log.explain("Answer: yes") if element.type == IliasElementType.FILE: return await self._handle_file(element, element_path) elif element.type == IliasElementType.FORUM: log.explain_topic(f"Decision: Crawl {fmt_path(element_path)}") log.explain("Forums are not supported") log.explain("Answer: No") return None elif element.type == IliasElementType.TEST: log.explain_topic(f"Decision: Crawl {fmt_path(element_path)}") log.explain("Tests contain no relevant files") log.explain("Answer: No") return None elif element.type == IliasElementType.LINK: return await self._handle_link(element, element_path) elif element.type == IliasElementType.BOOKING: return await self._handle_booking(element, element_path) elif element.type == IliasElementType.VIDEO: return await self._handle_file(element, element_path) elif element.type == IliasElementType.VIDEO_PLAYER: return await self._handle_video(element, element_path) elif element.type in _DIRECTORY_PAGES: return await self._handle_ilias_page(element.url, element, element_path) else: # This will retry it a few times, failing everytime. It doesn't make any network # requests, so that's fine. raise CrawlWarning(f"Unknown element type: {element.type!r}") async def _handle_link( self, element: IliasPageElement, element_path: PurePath, ) -> Optional[Awaitable[None]]: log.explain_topic(f"Decision: Crawl Link {fmt_path(element_path)}") log.explain(f"Links type is {self._links}") link_template_maybe = self._links.template() link_extension = self._links.extension() if not link_template_maybe or not link_extension: log.explain("Answer: No") return None else: log.explain("Answer: Yes") element_path = element_path.with_name(element_path.name + link_extension) maybe_dl = await self.download(element_path, mtime=element.mtime) if not maybe_dl: return None return self._download_link(element, link_template_maybe, maybe_dl) @_iorepeat(3, "resolving link") async def _download_link(self, element: IliasPageElement, link_template: str, dl: DownloadToken) -> None: async with dl as (bar, sink): export_url = element.url.replace("cmd=calldirectlink", "cmd=exportHTML") real_url = await self._resolve_link_target(export_url) self._write_link_content(link_template, real_url, element.name, element.description, sink) def _write_link_content( self, link_template: str, url: str, name: str, description: Optional[str], sink: FileSink, ) -> None: content = link_template content = content.replace("{{link}}", url) content = content.replace("{{name}}", name) content = content.replace("{{description}}", str(description)) content = content.replace("{{redirect_delay}}", str(self._link_file_redirect_delay)) sink.file.write(content.encode("utf-8")) sink.done() async def _handle_booking( self, element: IliasPageElement, element_path: PurePath, ) -> Optional[Awaitable[None]]: log.explain_topic(f"Decision: Crawl Booking Link {fmt_path(element_path)}") log.explain(f"Links type is {self._links}") link_template_maybe = self._links.template() link_extension = self._links.extension() if not link_template_maybe or not link_extension: log.explain("Answer: No") return None else: log.explain("Answer: Yes") element_path = element_path.with_name(element_path.name + link_extension) maybe_dl = await self.download(element_path, mtime=element.mtime) if not maybe_dl: return None return self._download_booking(element, link_template_maybe, maybe_dl) @_iorepeat(3, "resolving booking") async def _download_booking( self, element: IliasPageElement, link_template: str, dl: DownloadToken, ) -> None: async with dl as (bar, sink): self._write_link_content(link_template, element.url, element.name, element.description, sink) async def _resolve_link_target(self, export_url: str) -> str: async with self.session.get(export_url, allow_redirects=False) as resp: # No redirect means we were authenticated if hdrs.LOCATION not in resp.headers: return soupify(await resp.read()).select_one("a").get("href").strip() self._authenticate() async with self.session.get(export_url, allow_redirects=False) as resp: # No redirect means we were authenticated if hdrs.LOCATION not in resp.headers: return soupify(await resp.read()).select_one("a").get("href").strip() raise CrawlError("resolve_link_target failed even after authenticating") async def _handle_video( self, element: IliasPageElement, element_path: PurePath, ) -> Optional[Awaitable[None]]: # Videos will NOT be redownloaded - their content doesn't really change and they are chunky maybe_dl = await self.download(element_path, mtime=element.mtime, redownload=Redownload.NEVER) if not maybe_dl: return None return self._download_video(element, maybe_dl) @_iorepeat(3, "downloading video") async def _download_video(self, element: IliasPageElement, dl: DownloadToken) -> None: async with dl as (bar, sink): page = IliasPage(await self._get_page(element.url), element.url, element) real_element = page.get_child_elements()[0] log.explain(f"Streaming video from real url {real_element.url}") await self._stream_from_url(real_element.url, sink, bar, is_video=True) async def _handle_file( self, element: IliasPageElement, element_path: PurePath, ) -> Optional[Awaitable[None]]: maybe_dl = await self.download(element_path, mtime=element.mtime) if not maybe_dl: return None return self._download_file(element, maybe_dl) @_iorepeat(3, "downloading file") async def _download_file(self, element: IliasPageElement, dl: DownloadToken) -> None: assert dl # The function is only reached when dl is not None async with dl as (bar, sink): await self._stream_from_url(element.url, sink, bar, is_video=False) async def _stream_from_url(self, url: str, sink: FileSink, bar: ProgressBar, is_video: bool) -> None: async def try_stream() -> bool: async with self.session.get(url, allow_redirects=is_video) as resp: if not is_video: # Redirect means we weren't authenticated if hdrs.LOCATION in resp.headers: return False # we wanted a video but got HTML if is_video and "html" in resp.content_type: return False if resp.content_length: bar.set_total(resp.content_length) async for data in resp.content.iter_chunked(1024): sink.file.write(data) bar.advance(len(data)) sink.done() return True auth_id = await self._current_auth_id() if await try_stream(): return await self.authenticate(auth_id) if not await try_stream(): raise CrawlError("File streaming failed after authenticate()") async def _get_page(self, url: str) -> BeautifulSoup: auth_id = await self._current_auth_id() async with self.session.get(url) as request: soup = soupify(await request.read()) if self._is_logged_in(soup): return soup # We weren't authenticated, so try to do that await self.authenticate(auth_id) # Retry once after authenticating. If this fails, we will die. async with self.session.get(url) as request: soup = soupify(await request.read()) if self._is_logged_in(soup): return soup raise CrawlError("get_page failed even after authenticating") # We repeat this as the login method in shibboleth doesn't handle I/O errors. # Shibboleth is quite reliable as well, the repeat is likely not critical here. @_iorepeat(3, "Login") async def _authenticate(self) -> None: await self._shibboleth_login.login(self.session) @staticmethod def _is_logged_in(soup: BeautifulSoup) -> bool: # Normal ILIAS pages userlog = soup.find("li", {"id": "userlog"}) if userlog is not None: return True # Video listing embeds do not have complete ILIAS html. Try to match them by # their video listing table video_table = soup.find( recursive=True, name="table", attrs={"id": lambda x: x is not None and x.startswith("tbl_xoct")} ) if video_table is not None: return True # The individual video player wrapper page has nothing of the above. # Match it by its playerContainer. if soup.select_one("#playerContainer") is not None: return True return False class KitShibbolethLogin: """ Login via KIT's shibboleth system. """ def __init__(self, authenticator: Authenticator, tfa_authenticator: Optional[Authenticator]) -> None: self._auth = authenticator self._tfa_auth = tfa_authenticator async def login(self, sess: aiohttp.ClientSession) -> None: """ Performs the ILIAS Shibboleth authentication dance and saves the login cookies it receieves. This function should only be called whenever it is detected that you're not logged in. The cookies obtained should be good for a few minutes, maybe even an hour or two. """ # Equivalent: Click on "Mit KIT-Account anmelden" button in # https://ilias.studium.kit.edu/login.php url = "https://ilias.studium.kit.edu/Shibboleth.sso/Login" data = { "sendLogin": "1", "idp_selection": "https://idp.scc.kit.edu/idp/shibboleth", "target": "/shib_login.php", "home_organization_selection": "Mit KIT-Account anmelden", } soup: BeautifulSoup = await _post(sess, url, data) # Attempt to login using credentials, if necessary while not self._login_successful(soup): # Searching the form here so that this fails before asking for # credentials rather than after asking. form = soup.find("form", {"class": "full content", "method": "post"}) action = form["action"] csrf_token = form.find("input", {"name": "csrf_token"})["value"] # Equivalent: Enter credentials in # https://idp.scc.kit.edu/idp/profile/SAML2/Redirect/SSO url = "https://idp.scc.kit.edu" + action username, password = await self._auth.credentials() data = { "_eventId_proceed": "", "j_username": username, "j_password": password, "csrf_token": csrf_token } soup = await _post(sess, url, data) if self._tfa_required(soup): soup = await self._authenticate_tfa(sess, soup) if not self._login_successful(soup): self._auth.invalidate_credentials() # Equivalent: Being redirected via JS automatically # (or clicking "Continue" if you have JS disabled) relay_state = soup.find("input", {"name": "RelayState"}) saml_response = soup.find("input", {"name": "SAMLResponse"}) url = "https://ilias.studium.kit.edu/Shibboleth.sso/SAML2/POST" data = { # using the info obtained in the while loop above "RelayState": relay_state["value"], "SAMLResponse": saml_response["value"], } await sess.post(url, data=data) async def _authenticate_tfa( self, session: aiohttp.ClientSession, soup: BeautifulSoup ) -> BeautifulSoup: if not self._tfa_auth: self._tfa_auth = TfaAuthenticator("ilias-anon-tfa") tfa_token = await self._tfa_auth.password() # Searching the form here so that this fails before asking for # credentials rather than after asking. form = soup.find("form", {"method": "post"}) action = form["action"] csrf_token = form.find("input", {"name": "csrf_token"})["value"] # Equivalent: Enter token in # https://idp.scc.kit.edu/idp/profile/SAML2/Redirect/SSO url = "https://idp.scc.kit.edu" + action data = { "_eventId_proceed": "", "j_tokenNumber": tfa_token, "csrf_token": csrf_token } return await _post(session, url, data) @staticmethod def _login_successful(soup: BeautifulSoup) -> bool: relay_state = soup.find("input", {"name": "RelayState"}) saml_response = soup.find("input", {"name": "SAMLResponse"}) return relay_state is not None and saml_response is not None @staticmethod def _tfa_required(soup: BeautifulSoup) -> bool: return soup.find(id="j_tokenNumber") is not None async def _post(session: aiohttp.ClientSession, url: str, data: Any) -> BeautifulSoup: async with session.post(url, data=data) as response: return soupify(await response.read())