102 lines
2.1 KiB
C
102 lines
2.1 KiB
C
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/*
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* net/sched/em_cmp.c Simple packet data comparison ematch
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/tc_ematch/tc_em_cmp.h>
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#include <net/pkt_cls.h>
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static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
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{
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return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
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}
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static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
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struct tcf_pkt_info *info)
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{
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struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
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unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
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u32 val = 0;
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if (!tcf_valid_offset(skb, ptr, cmp->align))
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return 0;
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switch (cmp->align) {
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case TCF_EM_ALIGN_U8:
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val = *ptr;
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break;
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case TCF_EM_ALIGN_U16:
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val = *ptr << 8;
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val |= *(ptr+1);
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if (cmp_needs_transformation(cmp))
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val = be16_to_cpu(val);
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break;
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case TCF_EM_ALIGN_U32:
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/* Worth checking boundries? The branching seems
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* to get worse. Visit again. */
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val = *ptr << 24;
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val |= *(ptr+1) << 16;
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val |= *(ptr+2) << 8;
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val |= *(ptr+3);
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if (cmp_needs_transformation(cmp))
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val = be32_to_cpu(val);
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break;
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default:
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return 0;
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}
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if (cmp->mask)
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val &= cmp->mask;
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switch (cmp->opnd) {
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case TCF_EM_OPND_EQ:
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return val == cmp->val;
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case TCF_EM_OPND_LT:
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return val < cmp->val;
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case TCF_EM_OPND_GT:
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return val > cmp->val;
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}
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return 0;
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}
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static struct tcf_ematch_ops em_cmp_ops = {
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.kind = TCF_EM_CMP,
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.datalen = sizeof(struct tcf_em_cmp),
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.match = em_cmp_match,
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.owner = THIS_MODULE,
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.link = LIST_HEAD_INIT(em_cmp_ops.link)
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};
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static int __init init_em_cmp(void)
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{
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return tcf_em_register(&em_cmp_ops);
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}
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static void __exit exit_em_cmp(void)
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{
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tcf_em_unregister(&em_cmp_ops);
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}
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MODULE_LICENSE("GPL");
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module_init(init_em_cmp);
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module_exit(exit_em_cmp);
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