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.venv/Lib/site-packages/pip/_internal/index/collector.py

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+"""
+The main purpose of this module is to expose LinkCollector.collect_sources().
+"""
+
+import cgi
+import collections
+import functools
+import itertools
+import logging
+import os
+import re
+import urllib.parse
+import urllib.request
+import xml.etree.ElementTree
+from html.parser import HTMLParser
+from optparse import Values
+from typing import (
+    TYPE_CHECKING,
+    Callable,
+    Dict,
+    Iterable,
+    List,
+    MutableMapping,
+    NamedTuple,
+    Optional,
+    Sequence,
+    Tuple,
+    Union,
+)
+
+from pip._vendor import html5lib, requests
+from pip._vendor.requests import Response
+from pip._vendor.requests.exceptions import RetryError, SSLError
+
+from pip._internal.exceptions import NetworkConnectionError
+from pip._internal.models.link import Link
+from pip._internal.models.search_scope import SearchScope
+from pip._internal.network.session import PipSession
+from pip._internal.network.utils import raise_for_status
+from pip._internal.utils.filetypes import is_archive_file
+from pip._internal.utils.misc import pairwise, redact_auth_from_url
+from pip._internal.vcs import vcs
+
+from .sources import CandidatesFromPage, LinkSource, build_source
+
+if TYPE_CHECKING:
+    from typing import Protocol
+else:
+    Protocol = object
+
+logger = logging.getLogger(__name__)
+
+HTMLElement = xml.etree.ElementTree.Element
+ResponseHeaders = MutableMapping[str, str]
+
+
+def _match_vcs_scheme(url: str) -> Optional[str]:
+    """Look for VCS schemes in the URL.
+
+    Returns the matched VCS scheme, or None if there's no match.
+    """
+    for scheme in vcs.schemes:
+        if url.lower().startswith(scheme) and url[len(scheme)] in "+:":
+            return scheme
+    return None
+
+
+class _NotHTML(Exception):
+    def __init__(self, content_type: str, request_desc: str) -> None:
+        super().__init__(content_type, request_desc)
+        self.content_type = content_type
+        self.request_desc = request_desc
+
+
+def _ensure_html_header(response: Response) -> None:
+    """Check the Content-Type header to ensure the response contains HTML.
+
+    Raises `_NotHTML` if the content type is not text/html.
+    """
+    content_type = response.headers.get("Content-Type", "")
+    if not content_type.lower().startswith("text/html"):
+        raise _NotHTML(content_type, response.request.method)
+
+
+class _NotHTTP(Exception):
+    pass
+
+
+def _ensure_html_response(url: str, session: PipSession) -> None:
+    """Send a HEAD request to the URL, and ensure the response contains HTML.
+
+    Raises `_NotHTTP` if the URL is not available for a HEAD request, or
+    `_NotHTML` if the content type is not text/html.
+    """
+    scheme, netloc, path, query, fragment = urllib.parse.urlsplit(url)
+    if scheme not in {"http", "https"}:
+        raise _NotHTTP()
+
+    resp = session.head(url, allow_redirects=True)
+    raise_for_status(resp)
+
+    _ensure_html_header(resp)
+
+
+def _get_html_response(url: str, session: PipSession) -> Response:
+    """Access an HTML page with GET, and return the response.
+
+    This consists of three parts:
+
+    1. If the URL looks suspiciously like an archive, send a HEAD first to
+       check the Content-Type is HTML, to avoid downloading a large file.
+       Raise `_NotHTTP` if the content type cannot be determined, or
+       `_NotHTML` if it is not HTML.
+    2. Actually perform the request. Raise HTTP exceptions on network failures.
+    3. Check the Content-Type header to make sure we got HTML, and raise
+       `_NotHTML` otherwise.
+    """
+    if is_archive_file(Link(url).filename):
+        _ensure_html_response(url, session=session)
+
+    logger.debug("Getting page %s", redact_auth_from_url(url))
+
+    resp = session.get(
+        url,
+        headers={
+            "Accept": "text/html",
+            # We don't want to blindly returned cached data for
+            # /simple/, because authors generally expecting that
+            # twine upload && pip install will function, but if
+            # they've done a pip install in the last ~10 minutes
+            # it won't. Thus by setting this to zero we will not
+            # blindly use any cached data, however the benefit of
+            # using max-age=0 instead of no-cache, is that we will
+            # still support conditional requests, so we will still
+            # minimize traffic sent in cases where the page hasn't
+            # changed at all, we will just always incur the round
+            # trip for the conditional GET now instead of only
+            # once per 10 minutes.
+            # For more information, please see pypa/pip#5670.
+            "Cache-Control": "max-age=0",
+        },
+    )
+    raise_for_status(resp)
+
+    # The check for archives above only works if the url ends with
+    # something that looks like an archive. However that is not a
+    # requirement of an url. Unless we issue a HEAD request on every
+    # url we cannot know ahead of time for sure if something is HTML
+    # or not. However we can check after we've downloaded it.
+    _ensure_html_header(resp)
+
+    return resp
+
+
+def _get_encoding_from_headers(headers: ResponseHeaders) -> Optional[str]:
+    """Determine if we have any encoding information in our headers."""
+    if headers and "Content-Type" in headers:
+        content_type, params = cgi.parse_header(headers["Content-Type"])
+        if "charset" in params:
+            return params["charset"]
+    return None
+
+
+def _determine_base_url(document: HTMLElement, page_url: str) -> str:
+    """Determine the HTML document's base URL.
+
+    This looks for a ``<base>`` tag in the HTML document. If present, its href
+    attribute denotes the base URL of anchor tags in the document. If there is
+    no such tag (or if it does not have a valid href attribute), the HTML
+    file's URL is used as the base URL.
+
+    :param document: An HTML document representation. The current
+        implementation expects the result of ``html5lib.parse()``.
+    :param page_url: The URL of the HTML document.
+
+    TODO: Remove when `html5lib` is dropped.
+    """
+    for base in document.findall(".//base"):
+        href = base.get("href")
+        if href is not None:
+            return href
+    return page_url
+
+
+def _clean_url_path_part(part: str) -> str:
+    """
+    Clean a "part" of a URL path (i.e. after splitting on "@" characters).
+    """
+    # We unquote prior to quoting to make sure nothing is double quoted.
+    return urllib.parse.quote(urllib.parse.unquote(part))
+
+
+def _clean_file_url_path(part: str) -> str:
+    """
+    Clean the first part of a URL path that corresponds to a local
+    filesystem path (i.e. the first part after splitting on "@" characters).
+    """
+    # We unquote prior to quoting to make sure nothing is double quoted.
+    # Also, on Windows the path part might contain a drive letter which
+    # should not be quoted. On Linux where drive letters do not
+    # exist, the colon should be quoted. We rely on urllib.request
+    # to do the right thing here.
+    return urllib.request.pathname2url(urllib.request.url2pathname(part))
+
+
+# percent-encoded:                   /
+_reserved_chars_re = re.compile("(@|%2F)", re.IGNORECASE)
+
+
+def _clean_url_path(path: str, is_local_path: bool) -> str:
+    """
+    Clean the path portion of a URL.
+    """
+    if is_local_path:
+        clean_func = _clean_file_url_path
+    else:
+        clean_func = _clean_url_path_part
+
+    # Split on the reserved characters prior to cleaning so that
+    # revision strings in VCS URLs are properly preserved.
+    parts = _reserved_chars_re.split(path)
+
+    cleaned_parts = []
+    for to_clean, reserved in pairwise(itertools.chain(parts, [""])):
+        cleaned_parts.append(clean_func(to_clean))
+        # Normalize %xx escapes (e.g. %2f -> %2F)
+        cleaned_parts.append(reserved.upper())
+
+    return "".join(cleaned_parts)
+
+
+def _clean_link(url: str) -> str:
+    """
+    Make sure a link is fully quoted.
+    For example, if ' ' occurs in the URL, it will be replaced with "%20",
+    and without double-quoting other characters.
+    """
+    # Split the URL into parts according to the general structure
+    # `scheme://netloc/path;parameters?query#fragment`.
+    result = urllib.parse.urlparse(url)
+    # If the netloc is empty, then the URL refers to a local filesystem path.
+    is_local_path = not result.netloc
+    path = _clean_url_path(result.path, is_local_path=is_local_path)
+    return urllib.parse.urlunparse(result._replace(path=path))
+
+
+def _create_link_from_element(
+    element_attribs: Dict[str, Optional[str]],
+    page_url: str,
+    base_url: str,
+) -> Optional[Link]:
+    """
+    Convert an anchor element's attributes in a simple repository page to a Link.
+    """
+    href = element_attribs.get("href")
+    if not href:
+        return None
+
+    url = _clean_link(urllib.parse.urljoin(base_url, href))
+    pyrequire = element_attribs.get("data-requires-python")
+    yanked_reason = element_attribs.get("data-yanked")
+
+    link = Link(
+        url,
+        comes_from=page_url,
+        requires_python=pyrequire,
+        yanked_reason=yanked_reason,
+    )
+
+    return link
+
+
+class CacheablePageContent:
+    def __init__(self, page: "HTMLPage") -> None:
+        assert page.cache_link_parsing
+        self.page = page
+
+    def __eq__(self, other: object) -> bool:
+        return isinstance(other, type(self)) and self.page.url == other.page.url
+
+    def __hash__(self) -> int:
+        return hash(self.page.url)
+
+
+class ParseLinks(Protocol):
+    def __call__(
+        self, page: "HTMLPage", use_deprecated_html5lib: bool
+    ) -> Iterable[Link]:
+        ...
+
+
+def with_cached_html_pages(fn: ParseLinks) -> ParseLinks:
+    """
+    Given a function that parses an Iterable[Link] from an HTMLPage, cache the
+    function's result (keyed by CacheablePageContent), unless the HTMLPage
+    `page` has `page.cache_link_parsing == False`.
+    """
+
+    @functools.lru_cache(maxsize=None)
+    def wrapper(
+        cacheable_page: CacheablePageContent, use_deprecated_html5lib: bool
+    ) -> List[Link]:
+        return list(fn(cacheable_page.page, use_deprecated_html5lib))
+
+    @functools.wraps(fn)
+    def wrapper_wrapper(page: "HTMLPage", use_deprecated_html5lib: bool) -> List[Link]:
+        if page.cache_link_parsing:
+            return wrapper(CacheablePageContent(page), use_deprecated_html5lib)
+        return list(fn(page, use_deprecated_html5lib))
+
+    return wrapper_wrapper
+
+
+def _parse_links_html5lib(page: "HTMLPage") -> Iterable[Link]:
+    """
+    Parse an HTML document, and yield its anchor elements as Link objects.
+
+    TODO: Remove when `html5lib` is dropped.
+    """
+    document = html5lib.parse(
+        page.content,
+        transport_encoding=page.encoding,
+        namespaceHTMLElements=False,
+    )
+
+    url = page.url
+    base_url = _determine_base_url(document, url)
+    for anchor in document.findall(".//a"):
+        link = _create_link_from_element(
+            anchor.attrib,
+            page_url=url,
+            base_url=base_url,
+        )
+        if link is None:
+            continue
+        yield link
+
+
+@with_cached_html_pages
+def parse_links(page: "HTMLPage", use_deprecated_html5lib: bool) -> Iterable[Link]:
+    """
+    Parse an HTML document, and yield its anchor elements as Link objects.
+    """
+
+    if use_deprecated_html5lib:
+        yield from _parse_links_html5lib(page)
+        return
+
+    parser = HTMLLinkParser(page.url)
+    encoding = page.encoding or "utf-8"
+    parser.feed(page.content.decode(encoding))
+
+    url = page.url
+    base_url = parser.base_url or url
+    for anchor in parser.anchors:
+        link = _create_link_from_element(
+            anchor,
+            page_url=url,
+            base_url=base_url,
+        )
+        if link is None:
+            continue
+        yield link
+
+
+class HTMLPage:
+    """Represents one page, along with its URL"""
+
+    def __init__(
+        self,
+        content: bytes,
+        encoding: Optional[str],
+        url: str,
+        cache_link_parsing: bool = True,
+    ) -> None:
+        """
+        :param encoding: the encoding to decode the given content.
+        :param url: the URL from which the HTML was downloaded.
+        :param cache_link_parsing: whether links parsed from this page's url
+                                   should be cached. PyPI index urls should
+                                   have this set to False, for example.
+        """
+        self.content = content
+        self.encoding = encoding
+        self.url = url
+        self.cache_link_parsing = cache_link_parsing
+
+    def __str__(self) -> str:
+        return redact_auth_from_url(self.url)
+
+
+class HTMLLinkParser(HTMLParser):
+    """
+    HTMLParser that keeps the first base HREF and a list of all anchor
+    elements' attributes.
+    """
+
+    def __init__(self, url: str) -> None:
+        super().__init__(convert_charrefs=True)
+
+        self.url: str = url
+        self.base_url: Optional[str] = None
+        self.anchors: List[Dict[str, Optional[str]]] = []
+
+    def handle_starttag(self, tag: str, attrs: List[Tuple[str, Optional[str]]]) -> None:
+        if tag == "base" and self.base_url is None:
+            href = self.get_href(attrs)
+            if href is not None:
+                self.base_url = href
+        elif tag == "a":
+            self.anchors.append(dict(attrs))
+
+    def get_href(self, attrs: List[Tuple[str, Optional[str]]]) -> Optional[str]:
+        for name, value in attrs:
+            if name == "href":
+                return value
+        return None
+
+
+def _handle_get_page_fail(
+    link: Link,
+    reason: Union[str, Exception],
+    meth: Optional[Callable[..., None]] = None,
+) -> None:
+    if meth is None:
+        meth = logger.debug
+    meth("Could not fetch URL %s: %s - skipping", link, reason)
+
+
+def _make_html_page(response: Response, cache_link_parsing: bool = True) -> HTMLPage:
+    encoding = _get_encoding_from_headers(response.headers)
+    return HTMLPage(
+        response.content,
+        encoding=encoding,
+        url=response.url,
+        cache_link_parsing=cache_link_parsing,
+    )
+
+
+def _get_html_page(
+    link: Link, session: Optional[PipSession] = None
+) -> Optional["HTMLPage"]:
+    if session is None:
+        raise TypeError(
+            "_get_html_page() missing 1 required keyword argument: 'session'"
+        )
+
+    url = link.url.split("#", 1)[0]
+
+    # Check for VCS schemes that do not support lookup as web pages.
+    vcs_scheme = _match_vcs_scheme(url)
+    if vcs_scheme:
+        logger.warning(
+            "Cannot look at %s URL %s because it does not support lookup as web pages.",
+            vcs_scheme,
+            link,
+        )
+        return None
+
+    # Tack index.html onto file:// URLs that point to directories
+    scheme, _, path, _, _, _ = urllib.parse.urlparse(url)
+    if scheme == "file" and os.path.isdir(urllib.request.url2pathname(path)):
+        # add trailing slash if not present so urljoin doesn't trim
+        # final segment
+        if not url.endswith("/"):
+            url += "/"
+        url = urllib.parse.urljoin(url, "index.html")
+        logger.debug(" file: URL is directory, getting %s", url)
+
+    try:
+        resp = _get_html_response(url, session=session)
+    except _NotHTTP:
+        logger.warning(
+            "Skipping page %s because it looks like an archive, and cannot "
+            "be checked by a HTTP HEAD request.",
+            link,
+        )
+    except _NotHTML as exc:
+        logger.warning(
+            "Skipping page %s because the %s request got Content-Type: %s."
+            "The only supported Content-Type is text/html",
+            link,
+            exc.request_desc,
+            exc.content_type,
+        )
+    except NetworkConnectionError as exc:
+        _handle_get_page_fail(link, exc)
+    except RetryError as exc:
+        _handle_get_page_fail(link, exc)
+    except SSLError as exc:
+        reason = "There was a problem confirming the ssl certificate: "
+        reason += str(exc)
+        _handle_get_page_fail(link, reason, meth=logger.info)
+    except requests.ConnectionError as exc:
+        _handle_get_page_fail(link, f"connection error: {exc}")
+    except requests.Timeout:
+        _handle_get_page_fail(link, "timed out")
+    else:
+        return _make_html_page(resp, cache_link_parsing=link.cache_link_parsing)
+    return None
+
+
+class CollectedSources(NamedTuple):
+    find_links: Sequence[Optional[LinkSource]]
+    index_urls: Sequence[Optional[LinkSource]]
+
+
+class LinkCollector:
+
+    """
+    Responsible for collecting Link objects from all configured locations,
+    making network requests as needed.
+
+    The class's main method is its collect_sources() method.
+    """
+
+    def __init__(
+        self,
+        session: PipSession,
+        search_scope: SearchScope,
+    ) -> None:
+        self.search_scope = search_scope
+        self.session = session
+
+    @classmethod
+    def create(
+        cls,
+        session: PipSession,
+        options: Values,
+        suppress_no_index: bool = False,
+    ) -> "LinkCollector":
+        """
+        :param session: The Session to use to make requests.
+        :param suppress_no_index: Whether to ignore the --no-index option
+            when constructing the SearchScope object.
+        """
+        index_urls = [options.index_url] + options.extra_index_urls
+        if options.no_index and not suppress_no_index:
+            logger.debug(
+                "Ignoring indexes: %s",
+                ",".join(redact_auth_from_url(url) for url in index_urls),
+            )
+            index_urls = []
+
+        # Make sure find_links is a list before passing to create().
+        find_links = options.find_links or []
+
+        search_scope = SearchScope.create(
+            find_links=find_links,
+            index_urls=index_urls,
+        )
+        link_collector = LinkCollector(
+            session=session,
+            search_scope=search_scope,
+        )
+        return link_collector
+
+    @property
+    def find_links(self) -> List[str]:
+        return self.search_scope.find_links
+
+    def fetch_page(self, location: Link) -> Optional[HTMLPage]:
+        """
+        Fetch an HTML page containing package links.
+        """
+        return _get_html_page(location, session=self.session)
+
+    def collect_sources(
+        self,
+        project_name: str,
+        candidates_from_page: CandidatesFromPage,
+    ) -> CollectedSources:
+        # The OrderedDict calls deduplicate sources by URL.
+        index_url_sources = collections.OrderedDict(
+            build_source(
+                loc,
+                candidates_from_page=candidates_from_page,
+                page_validator=self.session.is_secure_origin,
+                expand_dir=False,
+                cache_link_parsing=False,
+            )
+            for loc in self.search_scope.get_index_urls_locations(project_name)
+        ).values()
+        find_links_sources = collections.OrderedDict(
+            build_source(
+                loc,
+                candidates_from_page=candidates_from_page,
+                page_validator=self.session.is_secure_origin,
+                expand_dir=True,
+                cache_link_parsing=True,
+            )
+            for loc in self.find_links
+        ).values()
+
+        if logger.isEnabledFor(logging.DEBUG):
+            lines = [
+                f"* {s.link}"
+                for s in itertools.chain(find_links_sources, index_url_sources)
+                if s is not None and s.link is not None
+            ]
+            lines = [
+                f"{len(lines)} location(s) to search "
+                f"for versions of {project_name}:"
+            ] + lines
+            logger.debug("\n".join(lines))
+
+        return CollectedSources(
+            find_links=list(find_links_sources),
+            index_urls=list(index_url_sources),
+        )