link.py

import functools
import logging
import os
import posixpath
import re
import urllib.parse
from typing import TYPE_CHECKING, Dict, List, NamedTuple, Optional, Tuple, Union

from pip._internal.utils.filetypes import WHEEL_EXTENSION
from pip._internal.utils.hashes import Hashes
from pip._internal.utils.misc import (
    redact_auth_from_url,
    split_auth_from_netloc,
    splitext,
)
from pip._internal.utils.models import KeyBasedCompareMixin
from pip._internal.utils.urls import path_to_url, url_to_path

if TYPE_CHECKING:
    from pip._internal.index.collector import HTMLPage

logger = logging.getLogger(__name__)


_SUPPORTED_HASHES = ("sha1", "sha224", "sha384", "sha256", "sha512", "md5")


class Link(KeyBasedCompareMixin):
    """Represents a parsed link from a Package Index's simple URL"""

    __slots__ = [
        "_parsed_url",
        "_url",
        "comes_from",
        "requires_python",
        "yanked_reason",
        "cache_link_parsing",
    ]

    def __init__(
        self,
        url: str,
        comes_from: Optional[Union[str, "HTMLPage"]] = None,
        requires_python: Optional[str] = None,
        yanked_reason: Optional[str] = None,
        cache_link_parsing: bool = True,
    ) -> None:
        """
        :param url: url of the resource pointed to (href of the link)
        :param comes_from: instance of HTMLPage where the link was found,
            or string.
        :param requires_python: String containing the `Requires-Python`
            metadata field, specified in PEP 345. This may be specified by
            a data-requires-python attribute in the HTML link tag, as
            described in PEP 503.
        :param yanked_reason: the reason the file has been yanked, if the
            file has been yanked, or None if the file hasn't been yanked.
            This is the value of the "data-yanked" attribute, if present, in
            a simple repository HTML link. If the file has been yanked but
            no reason was provided, this should be the empty string. See
            PEP 592 for more information and the specification.
        :param cache_link_parsing: A flag that is used elsewhere to determine
                                   whether resources retrieved from this link
                                   should be cached. PyPI index urls should
                                   generally have this set to False, for
                                   example.
        """

        # url can be a UNC windows share
        if url.startswith("\\\\"):
            url = path_to_url(url)

        self._parsed_url = urllib.parse.urlsplit(url)
        # Store the url as a private attribute to prevent accidentally
        # trying to set a new value.
        self._url = url

        self.comes_from = comes_from
        self.requires_python = requires_python if requires_python else None
        self.yanked_reason = yanked_reason

        super().__init__(key=url, defining_class=Link)

        self.cache_link_parsing = cache_link_parsing

    def __str__(self) -> str:
        if self.requires_python:
            rp = f" (requires-python:{self.requires_python})"
        else:
            rp = ""
        if self.comes_from:
            return "{} (from {}){}".format(
                redact_auth_from_url(self._url), self.comes_from, rp
            )
        else:
            return redact_auth_from_url(str(self._url))

    def __repr__(self) -> str:
        return f"<Link {self}>"

    @property
    def url(self) -> str:
        return self._url

    @property
    def filename(self) -> str:
        path = self.path.rstrip("/")
        name = posixpath.basename(path)
        if not name:
            # Make sure we don't leak auth information if the netloc
            # includes a username and password.
            netloc, user_pass = split_auth_from_netloc(self.netloc)
            return netloc

        name = urllib.parse.unquote(name)
        assert name, f"URL {self._url!r} produced no filename"
        return name

    @property
    def file_path(self) -> str:
        return url_to_path(self.url)

    @property
    def scheme(self) -> str:
        return self._parsed_url.scheme

    @property
    def netloc(self) -> str:
        """
        This can contain auth information.
        """
        return self._parsed_url.netloc

    @property
    def path(self) -> str:
        return urllib.parse.unquote(self._parsed_url.path)

    def splitext(self) -> Tuple[str, str]:
        return splitext(posixpath.basename(self.path.rstrip("/")))

    @property
    def ext(self) -> str:
        return self.splitext()[1]

    @property
    def url_without_fragment(self) -> str:
        scheme, netloc, path, query, fragment = self._parsed_url
        return urllib.parse.urlunsplit((scheme, netloc, path, query, ""))

    _egg_fragment_re = re.compile(r"[#&]egg=([^&]*)")

    @property
    def egg_fragment(self) -> Optional[str]:
        match = self._egg_fragment_re.search(self._url)
        if not match:
            return None
        return match.group(1)

    _subdirectory_fragment_re = re.compile(r"[#&]subdirectory=([^&]*)")

    @property
    def subdirectory_fragment(self) -> Optional[str]:
        match = self._subdirectory_fragment_re.search(self._url)
        if not match:
            return None
        return match.group(1)

    _hash_re = re.compile(
        r"({choices})=([a-f0-9]+)".format(choices="|".join(_SUPPORTED_HASHES))
    )

    @property
    def hash(self) -> Optional[str]:
        match = self._hash_re.search(self._url)
        if match:
            return match.group(2)
        return None

    @property
    def hash_name(self) -> Optional[str]:
        match = self._hash_re.search(self._url)
        if match:
            return match.group(1)
        return None

    @property
    def show_url(self) -> str:
        return posixpath.basename(self._url.split("#", 1)[0].split("?", 1)[0])

    @property
    def is_file(self) -> bool:
        return self.scheme == "file"

    def is_existing_dir(self) -> bool:
        return self.is_file and os.path.isdir(self.file_path)

    @property
    def is_wheel(self) -> bool:
        return self.ext == WHEEL_EXTENSION

    @property
    def is_vcs(self) -> bool:
        from pip._internal.vcs import vcs

        return self.scheme in vcs.all_schemes

    @property
    def is_yanked(self) -> bool:
        return self.yanked_reason is not None

    @property
    def has_hash(self) -> bool:
        return self.hash_name is not None

    def is_hash_allowed(self, hashes: Optional[Hashes]) -> bool:
        """
        Return True if the link has a hash and it is allowed.
        """
        if hashes is None or not self.has_hash:
            return False
        # Assert non-None so mypy knows self.hash_name and self.hash are str.
        assert self.hash_name is not None
        assert self.hash is not None

        return hashes.is_hash_allowed(self.hash_name, hex_digest=self.hash)


class _CleanResult(NamedTuple):
    """Convert link for equivalency check.

    This is used in the resolver to check whether two URL-specified requirements
    likely point to the same distribution and can be considered equivalent. This
    equivalency logic avoids comparing URLs literally, which can be too strict
    (e.g. "a=1&b=2" vs "b=2&a=1") and produce conflicts unexpecting to users.

    Currently this does three things:

    1. Drop the basic auth part. This is technically wrong since a server can
       serve different content based on auth, but if it does that, it is even
       impossible to guarantee two URLs without auth are equivalent, since
       the user can input different auth information when prompted. So the
       practical solution is to assume the auth doesn't affect the response.
    2. Parse the query to avoid the ordering issue. Note that ordering under the
       same key in the query are NOT cleaned; i.e. "a=1&a=2" and "a=2&a=1" are
       still considered different.
    3. Explicitly drop most of the fragment part, except ``subdirectory=`` and
       hash values, since it should have no impact the downloaded content. Note
       that this drops the "egg=" part historically used to denote the requested
       project (and extras), which is wrong in the strictest sense, but too many
       people are supplying it inconsistently to cause superfluous resolution
       conflicts, so we choose to also ignore them.
    """

    parsed: urllib.parse.SplitResult
    query: Dict[str, List[str]]
    subdirectory: str
    hashes: Dict[str, str]


def _clean_link(link: Link) -> _CleanResult:
    parsed = link._parsed_url
    netloc = parsed.netloc.rsplit("@", 1)[-1]
    # According to RFC 8089, an empty host in file: means localhost.
    if parsed.scheme == "file" and not netloc:
        netloc = "localhost"
    fragment = urllib.parse.parse_qs(parsed.fragment)
    if "egg" in fragment:
        logger.debug("Ignoring egg= fragment in %s", link)
    try:
        # If there are multiple subdirectory values, use the first one.
        # This matches the behavior of Link.subdirectory_fragment.
        subdirectory = fragment["subdirectory"][0]
    except (IndexError, KeyError):
        subdirectory = ""
    # If there are multiple hash values under the same algorithm, use the
    # first one. This matches the behavior of Link.hash_value.
    hashes = {k: fragment[k][0] for k in _SUPPORTED_HASHES if k in fragment}
    return _CleanResult(
        parsed=parsed._replace(netloc=netloc, query="", fragment=""),
        query=urllib.parse.parse_qs(parsed.query),
        subdirectory=subdirectory,
        hashes=hashes,
    )


@functools.lru_cache(maxsize=None)
def links_equivalent(link1: Link, link2: Link) -> bool:
    return _clean_link(link1) == _clean_link(link2)