include/net/ip6_checksum.h

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Checksumming functions for IPv6
   7  *
   8  * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
   9  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  10  *              Borrows very liberally from tcp.c and ip.c, see those
  11  *              files for more names.
  12  *
  13  *              This program is free software; you can redistribute it and/or
  14  *              modify it under the terms of the GNU General Public License
  15  *              as published by the Free Software Foundation; either version
  16  *              2 of the License, or (at your option) any later version.
  17  */
  18
  19 /*
  20  *      Fixes:
  21  *
  22  *      Ralf Baechle                    :       generic ipv6 checksum
  23  *      <ralf@waldorf-gmbh.de>
  24  */
  25
  26 #ifndef _CHECKSUM_IPV6_H
  27 #define _CHECKSUM_IPV6_H
  28
  29 #include <asm/types.h>
  30 #include <asm/byteorder.h>
  31 #include <net/ip.h>
  32 #include <asm/checksum.h>
  33 #include <linux/in6.h>
  34 #include <linux/tcp.h>
  35 #include <linux/ipv6.h>
  36
  37 #ifndef _HAVE_ARCH_IPV6_CSUM
  38
  39 static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
  40                                           const struct in6_addr *daddr,
  41                                           __u32 len, unsigned short proto,
  42                                           __wsum csum)
  43 {
  44
  45         int carry;
  46         __u32 ulen;
  47         __u32 uproto;
  48         __u32 sum = (__force u32)csum;
  49
  50         sum += (__force u32)saddr->s6_addr32[0];
  51         carry = (sum < (__force u32)saddr->s6_addr32[0]);
  52         sum += carry;
  53
  54         sum += (__force u32)saddr->s6_addr32[1];
  55         carry = (sum < (__force u32)saddr->s6_addr32[1]);
  56         sum += carry;
  57
  58         sum += (__force u32)saddr->s6_addr32[2];
  59         carry = (sum < (__force u32)saddr->s6_addr32[2]);
  60         sum += carry;
  61
  62         sum += (__force u32)saddr->s6_addr32[3];
  63         carry = (sum < (__force u32)saddr->s6_addr32[3]);
  64         sum += carry;
  65
  66         sum += (__force u32)daddr->s6_addr32[0];
  67         carry = (sum < (__force u32)daddr->s6_addr32[0]);
  68         sum += carry;
  69
  70         sum += (__force u32)daddr->s6_addr32[1];
  71         carry = (sum < (__force u32)daddr->s6_addr32[1]);
  72         sum += carry;
  73
  74         sum += (__force u32)daddr->s6_addr32[2];
  75         carry = (sum < (__force u32)daddr->s6_addr32[2]);
  76         sum += carry;
  77
  78         sum += (__force u32)daddr->s6_addr32[3];
  79         carry = (sum < (__force u32)daddr->s6_addr32[3]);
  80         sum += carry;
  81
  82         ulen = (__force u32)htonl((__u32) len);
  83         sum += ulen;
  84         carry = (sum < ulen);
  85         sum += carry;
  86
  87         uproto = (__force u32)htonl(proto);
  88         sum += uproto;
  89         carry = (sum < uproto);
  90         sum += carry;
  91
  92         return csum_fold((__force __wsum)sum);
  93 }
  94
  95 #endif
  96
  97 static __inline__ __sum16 tcp_v6_check(int len,
  98                                    const struct in6_addr *saddr,
  99                                    const struct in6_addr *daddr,
 100                                    __wsum base)
 101 {
 102         return csum_ipv6_magic(saddr, daddr, len, IPPROTO_TCP, base);
 103 }
 104
 105 static inline void __tcp_v6_send_check(struct sk_buff *skb,
 106                                        const struct in6_addr *saddr,
 107                                        const struct in6_addr *daddr)
 108 {
 109         struct tcphdr *th = tcp_hdr(skb);
 110
 111         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 112                 th->check = ~tcp_v6_check(skb->len, saddr, daddr, 0);
 113                 skb->csum_start = skb_transport_header(skb) - skb->head;
 114                 skb->csum_offset = offsetof(struct tcphdr, check);
 115         } else {
 116                 th->check = tcp_v6_check(skb->len, saddr, daddr,
 117                                          csum_partial(th, th->doff << 2,
 118                                                       skb->csum));
 119         }
 120 }
 121
 122 static inline void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
 123 {
 124         struct ipv6_pinfo *np = inet6_sk(sk);
 125
 126         __tcp_v6_send_check(skb, &np->saddr, &np->daddr);
 127 }
 128
 129 #endif