root/include/net/dsfield.h

INCLUDED FROM

DEFINITIONS

1. ipv4_get_dsfield
2. ipv6_get_dsfield
3. ipv4_change_dsfield
4. ipv6_change_dsfield

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* include/net/dsfield.h - Manipulation of the Differentiated Services field */
   3 
   4 /* Written 1998-2000 by Werner Almesberger, EPFL ICA */
   5 
   6 
   7 #ifndef __NET_DSFIELD_H
   8 #define __NET_DSFIELD_H
   9 
  10 #include <linux/types.h>
  11 #include <linux/ip.h>
  12 #include <linux/ipv6.h>
  13 #include <asm/byteorder.h>
  14 
  15 
  16 static inline __u8 ipv4_get_dsfield(const struct iphdr *iph)
  17 {
  18         return iph->tos;
  19 }
  20 
  21 
  22 static inline __u8 ipv6_get_dsfield(const struct ipv6hdr *ipv6h)
  23 {
  24         return ntohs(*(const __be16 *)ipv6h) >> 4;
  25 }
  26 
  27 
  28 static inline void ipv4_change_dsfield(struct iphdr *iph,__u8 mask,
  29     __u8 value)
  30 {
  31         __u32 check = ntohs((__force __be16)iph->check);
  32         __u8 dsfield;
  33 
  34         dsfield = (iph->tos & mask) | value;
  35         check += iph->tos;
  36         if ((check+1) >> 16) check = (check+1) & 0xffff;
  37         check -= dsfield;
  38         check += check >> 16; /* adjust carry */
  39         iph->check = (__force __sum16)htons(check);
  40         iph->tos = dsfield;
  41 }
  42 
  43 
  44 static inline void ipv6_change_dsfield(struct ipv6hdr *ipv6h,__u8 mask,
  45     __u8 value)
  46 {
  47         __be16 *p = (__force __be16 *)ipv6h;
  48 
  49         *p = (*p & htons((((u16)mask << 4) | 0xf00f))) | htons((u16)value << 4);
  50 }
  51 
  52 
  53 #endif