Validate Generic Netlink message headers.

    https://github.com/thom311/libnl/blob/libnl3_2_25/lib/genl/genl.c#L117

    Verifies the integrity of the Netlink and Generic Netlink headers by enforcing the following requirements:
    - Valid Netlink message header (`nlmsg_valid_hdr()`)
    - Presence of a complete Generic Netlink header
    - At least `hdrlen` bytes of payload included after the generic Netlink header.

    Positional arguments:
    nlh -- Netlink message header (nlmsghdr class instance).
    hdrlen -- length of user header (integer).

    Returns:
    True if the headers are valid or False if not.

def genlmsg_valid_hdr(nlh, hdrlen):
    """Validate Generic Netlink message headers.

    https://github.com/thom311/libnl/blob/libnl3_2_25/lib/genl/genl.c#L117

    Verifies the integrity of the Netlink and Generic Netlink headers by enforcing the following requirements:
    - Valid Netlink message header (`nlmsg_valid_hdr()`)
    - Presence of a complete Generic Netlink header
    - At least `hdrlen` bytes of payload included after the generic Netlink header.

    Positional arguments:
    nlh -- Netlink message header (nlmsghdr class instance).
    hdrlen -- length of user header (integer).

    Returns:
    True if the headers are valid or False if not.
    """
    if not nlmsg_valid_hdr(nlh, GENL_HDRLEN):
        return False

    ghdr = genlmsghdr(nlmsg_data(nlh))
    if genlmsg_len(ghdr) < NLMSG_ALIGN(hdrlen):
        return False

    return True