em_u32.c

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/*
 * net/sched/em_u32.c   U32 Ematch
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * Authors: Thomas Graf <[email protected]>
 *      Alexey Kuznetsov, <[email protected]>
 *
 * Based on net/sched/cls_u32.c
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <net/pkt_cls.h>

static int em_u32_match(struct sk_buff *skb, struct tcf_ematch *em,
            struct tcf_pkt_info *info)
{
    struct tc_u32_key *key = (struct tc_u32_key *) em->data;
    const unsigned char *ptr = skb_network_header(skb);

    if (info) {
        if (info->ptr)
            ptr = info->ptr;
        ptr += (info->nexthdr & key->offmask);
    }

    ptr += key->off;

    if (!tcf_valid_offset(skb, ptr, sizeof(u32)))
        return 0;

    return !(((*(__be32 *) ptr)  ^ key->val) & key->mask);
}

static struct tcf_ematch_ops em_u32_ops = {
    .kind     = TCF_EM_U32,
    .datalen  = sizeof(struct tc_u32_key),
    .match    = em_u32_match,
    .owner    = THIS_MODULE,
    .link     = LIST_HEAD_INIT(em_u32_ops.link)
};

static int __init init_em_u32(void)
{
    return tcf_em_register(&em_u32_ops);
}

static void __exit exit_em_u32(void)
{
    tcf_em_unregister(&em_u32_ops);
}

MODULE_LICENSE("GPL");

module_init(init_em_u32);
module_exit(exit_em_u32);

MODULE_ALIAS_TCF_EMATCH(TCF_EM_U32);