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/*
* net/sched/em_cmp.c Simple packet data comparison 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 <tgraf@suug.ch>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/tc_ematch/tc_em_cmp.h>
#include <net/pkt_cls.h>
static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
{
return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
}
static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
struct tcf_pkt_info *info)
{
struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
u32 val = 0;
if (!tcf_valid_offset(skb, ptr, cmp->align))
return 0;
switch (cmp->align) {
case TCF_EM_ALIGN_U8:
val = *ptr;
break;
case TCF_EM_ALIGN_U16:
val = *ptr << 8;
val |= *(ptr+1);
if (cmp_needs_transformation(cmp))
val = be16_to_cpu(val);
break;
case TCF_EM_ALIGN_U32:
/* Worth checking boundries? The branching seems
* to get worse. Visit again. */
val = *ptr << 24;
val |= *(ptr+1) << 16;
val |= *(ptr+2) << 8;
val |= *(ptr+3);
if (cmp_needs_transformation(cmp))
val = be32_to_cpu(val);
break;
default:
return 0;
}
if (cmp->mask)
val &= cmp->mask;
switch (cmp->opnd) {
case TCF_EM_OPND_EQ:
return val == cmp->val;
case TCF_EM_OPND_LT:
return val < cmp->val;
case TCF_EM_OPND_GT:
return val > cmp->val;
}
return 0;
}
static struct tcf_ematch_ops em_cmp_ops = {
.kind = TCF_EM_CMP,
.datalen = sizeof(struct tcf_em_cmp),
.match = em_cmp_match,
.owner = THIS_MODULE,
.link = LIST_HEAD_INIT(em_cmp_ops.link)
};
static int __init init_em_cmp(void)
{
return tcf_em_register(&em_cmp_ops);
}
static void __exit exit_em_cmp(void)
{
tcf_em_unregister(&em_cmp_ops);
}
MODULE_LICENSE("GPL");
module_init(init_em_cmp);
module_exit(exit_em_cmp);
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