Function should_bypass_proxies

src/requests/utils.py:810–870

Returns whether we should bypass proxies or not. :rtype: bool

(url: str, no_proxy: str | None)

def should_bypass_proxies(url: str, no_proxy: str | None) -> bool:
    """
    Returns whether we should bypass proxies or not.

    :rtype: bool
    """

    # Prioritize lowercase environment variables over uppercase
    # to keep a consistent behaviour with other http projects (curl, wget).
    def get_proxy(key: str) -> str | None:
        return os.environ.get(key) or os.environ.get(key.upper())

    # First check whether no_proxy is defined. If it is, check that the URL
    # we're getting isn't in the no_proxy list.
    no_proxy_arg = no_proxy
    if no_proxy is None:
        no_proxy = get_proxy("no_proxy")
    parsed = urlparse(url)
    hostname = parsed.hostname

    if hostname is None:
        # URLs don't always have hostnames, e.g. file:/// urls.
        return True

    if no_proxy:
        # We need to check whether we match here. We need to see if we match
        # the end of the hostname, both with and without the port.
        no_proxy_hosts = (host for host in no_proxy.replace(" ", "").split(",") if host)

        if is_ipv4_address(hostname):
            for proxy_ip in no_proxy_hosts:
                if is_valid_cidr(proxy_ip):
                    if address_in_network(hostname, proxy_ip):
                        return True
                elif hostname == proxy_ip:
                    # If no_proxy ip was defined in plain IP notation instead of cidr notation &
                    # matches the IP of the index
                    return True
        else:
            host_with_port = hostname
            if parsed.port:
                host_with_port += f":{parsed.port}"

            for host in no_proxy_hosts:
                host = host.lstrip(".")
                if hostname == host or host_with_port == host:
                    return True
                host = "." + host
                if hostname.endswith(host) or host_with_port.endswith(host):
                    return True

    with set_environ("no_proxy", no_proxy_arg):
        try:
            bypass = proxy_bypass(hostname)
        except (TypeError, socket.gaierror):
            bypass = False

    if bypass: