linux/include/net/dsfield.h
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   1/* include/net/dsfield.h - Manipulation of the Differentiated Services field */
   2
   3/* Written 1998-2000 by Werner Almesberger, EPFL ICA */
   4
   5
   6#ifndef __NET_DSFIELD_H
   7#define __NET_DSFIELD_H
   8
   9#include <linux/types.h>
  10#include <linux/ip.h>
  11#include <linux/ipv6.h>
  12#include <asm/byteorder.h>
  13
  14
  15static inline __u8 ipv4_get_dsfield(const struct iphdr *iph)
  16{
  17        return iph->tos;
  18}
  19
  20
  21static inline __u8 ipv6_get_dsfield(const struct ipv6hdr *ipv6h)
  22{
  23        return ntohs(*(const __be16 *)ipv6h) >> 4;
  24}
  25
  26
  27static inline void ipv4_change_dsfield(struct iphdr *iph,__u8 mask,
  28    __u8 value)
  29{
  30        __u32 check = ntohs((__force __be16)iph->check);
  31        __u8 dsfield;
  32
  33        dsfield = (iph->tos & mask) | value;
  34        check += iph->tos;
  35        if ((check+1) >> 16) check = (check+1) & 0xffff;
  36        check -= dsfield;
  37        check += check >> 16; /* adjust carry */
  38        iph->check = (__force __sum16)htons(check);
  39        iph->tos = dsfield;
  40}
  41
  42
  43static inline void ipv6_change_dsfield(struct ipv6hdr *ipv6h,__u8 mask,
  44    __u8 value)
  45{
  46        __u16 tmp;
  47
  48        tmp = ntohs(*(__be16 *) ipv6h);
  49        tmp = (tmp & ((mask << 4) | 0xf00f)) | (value << 4);
  50        *(__be16 *) ipv6h = htons(tmp);
  51}
  52
  53
  54#endif
  55
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