https://github.com/thom311/libnl/blob/libnl3_2_25/lib/msg.c#L929.

    Positional arguments:
    msg -- Netlink message (nl_msg class instance).
    ofd -- function to call with arguments similar to `logging.debug`.
    hdr -- Netlink message header (nlmsghdr class instance).

def print_msg(msg, ofd, hdr):
    """https://github.com/thom311/libnl/blob/libnl3_2_25/lib/msg.c#L929.

    Positional arguments:
    msg -- Netlink message (nl_msg class instance).
    ofd -- function to call with arguments similar to `logging.debug`.
    hdr -- Netlink message header (nlmsghdr class instance).
    """
    payloadlen = c_int(nlmsg_len(hdr))
    attrlen = 0
    data = nlmsg_data(hdr)
    ops = nl_cache_ops_associate_safe(msg.nm_protocol, hdr.nlmsg_type)
    if ops:
        attrlen = nlmsg_attrlen(hdr, ops.co_hdrsize)
        payloadlen.value -= attrlen
    if msg.nm_protocol == libnl.linux_private.netlink.NETLINK_GENERIC:
        data = print_genl_msg(msg, ofd, hdr, ops, payloadlen)
    if payloadlen.value:
        ofd('  [PAYLOAD] %d octets', payloadlen.value)
        dump_hex(ofd, data, payloadlen.value, 0)
    if attrlen:
        attrs = nlmsg_attrdata(hdr, ops.co_hdrsize)
        attrlen = nlmsg_attrlen(hdr, ops.co_hdrsize)
        dump_attrs(ofd, attrs, attrlen, 0)