venv/lib/python3.11/site-packages/werkzeug/sansio/utils.py

from __future__ import annotations

import typing as t
from urllib.parse import quote

from .._internal import _plain_int
from ..exceptions import SecurityError
from ..urls import uri_to_iri


def host_is_trusted(hostname: str | None, trusted_list: t.Iterable[str]) -> bool:
    """Check if a host matches a list of trusted names.

    :param hostname: The name to check.
    :param trusted_list: A list of valid names to match. If a name
        starts with a dot it will match all subdomains.

    .. versionadded:: 0.9
    """
    if not hostname:
        return False

    try:
        hostname = hostname.partition(":")[0].encode("idna").decode("ascii")
    except UnicodeEncodeError:
        return False

    if isinstance(trusted_list, str):
        trusted_list = [trusted_list]

    for ref in trusted_list:
        if ref.startswith("."):
            ref = ref[1:]
            suffix_match = True
        else:
            suffix_match = False

        try:
            ref = ref.partition(":")[0].encode("idna").decode("ascii")
        except UnicodeEncodeError:
            return False

        if ref == hostname or (suffix_match and hostname.endswith(f".{ref}")):
            return True

    return False


def get_host(
    scheme: str,
    host_header: str | None,
    server: tuple[str, int | None] | None = None,
    trusted_hosts: t.Iterable[str] | None = None,
) -> str:
    """Return the host for the given parameters.

    This first checks the ``host_header``. If it's not present, then
    ``server`` is used. The host will only contain the port if it is
    different than the standard port for the protocol.

    Optionally, verify that the host is trusted using
    :func:`host_is_trusted` and raise a
    :exc:`~werkzeug.exceptions.SecurityError` if it is not.

    :param scheme: The protocol the request used, like ``"https"``.
    :param host_header: The ``Host`` header value.
    :param server: Address of the server. ``(host, port)``, or
        ``(path, None)`` for unix sockets.
    :param trusted_hosts: A list of trusted host names.

    :return: Host, with port if necessary.
    :raise ~werkzeug.exceptions.SecurityError: If the host is not
        trusted.

    .. versionchanged:: 3.1.3
        If ``SERVER_NAME`` is IPv6, it is wrapped in ``[]``.
    """
    host = ""

    if host_header is not None:
        host = host_header
    elif server is not None:
        host = server[0]

        # If SERVER_NAME is IPv6, wrap it in [] to match Host header.
        # Check for : because domain or IPv4 can't have that.
        if ":" in host and host[0] != "[":
            host = f"[{host}]"

        if server[1] is not None:
            host = f"{host}:{server[1]}"

    if scheme in {"http", "ws"} and host.endswith(":80"):
        host = host[:-3]
    elif scheme in {"https", "wss"} and host.endswith(":443"):
        host = host[:-4]

    if trusted_hosts is not None:
        if not host_is_trusted(host, trusted_hosts):
            raise SecurityError(f"Host {host!r} is not trusted.")

    return host


def get_current_url(
    scheme: str,
    host: str,
    root_path: str | None = None,
    path: str | None = None,
    query_string: bytes | None = None,
) -> str:
    """Recreate the URL for a request. If an optional part isn't
    provided, it and subsequent parts are not included in the URL.

    The URL is an IRI, not a URI, so it may contain Unicode characters.
    Use :func:`~werkzeug.urls.iri_to_uri` to convert it to ASCII.

    :param scheme: The protocol the request used, like ``"https"``.
    :param host: The host the request was made to. See :func:`get_host`.
    :param root_path: Prefix that the application is mounted under. This
        is prepended to ``path``.
    :param path: The path part of the URL after ``root_path``.
    :param query_string: The portion of the URL after the "?".
    """
    url = [scheme, "://", host]

    if root_path is None:
        url.append("/")
        return uri_to_iri("".join(url))

    # safe = https://url.spec.whatwg.org/#url-path-segment-string
    # as well as percent for things that are already quoted
    url.append(quote(root_path.rstrip("/"), safe="!$&'()*+,/:;=@%"))
    url.append("/")

    if path is None:
        return uri_to_iri("".join(url))

    url.append(quote(path.lstrip("/"), safe="!$&'()*+,/:;=@%"))

    if query_string:
        url.append("?")
        url.append(quote(query_string, safe="!$&'()*+,/:;=?@%"))

    return uri_to_iri("".join(url))


def get_content_length(
    http_content_length: str | None = None,
    http_transfer_encoding: str | None = None,
) -> int | None:
    """Return the ``Content-Length`` header value as an int. If the header is not given
    or the ``Transfer-Encoding`` header is ``chunked``, ``None`` is returned to indicate
    a streaming request. If the value is not an integer, or negative, 0 is returned.

    :param http_content_length: The Content-Length HTTP header.
    :param http_transfer_encoding: The Transfer-Encoding HTTP header.

    .. versionadded:: 2.2
    """
    if http_transfer_encoding == "chunked" or http_content_length is None:
        return None

    try:
        return max(0, _plain_int(http_content_length))
    except ValueError:
        return 0