net/ipv6/ip6_checksum.c

   1 #include <net/ip.h>
   2 #include <net/udp.h>
   3 #include <net/udplite.h>
   4 #include <asm/checksum.h>
   5
   6 #ifndef _HAVE_ARCH_IPV6_CSUM
   7 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
   8                         const struct in6_addr *daddr,
   9                         __u32 len, unsigned short proto,
  10                         __wsum csum)
  11 {
  12
  13         int carry;
  14         __u32 ulen;
  15         __u32 uproto;
  16         __u32 sum = (__force u32)csum;
  17
  18         sum += (__force u32)saddr->s6_addr32[0];
  19         carry = (sum < (__force u32)saddr->s6_addr32[0]);
  20         sum += carry;
  21
  22         sum += (__force u32)saddr->s6_addr32[1];
  23         carry = (sum < (__force u32)saddr->s6_addr32[1]);
  24         sum += carry;
  25
  26         sum += (__force u32)saddr->s6_addr32[2];
  27         carry = (sum < (__force u32)saddr->s6_addr32[2]);
  28         sum += carry;
  29
  30         sum += (__force u32)saddr->s6_addr32[3];
  31         carry = (sum < (__force u32)saddr->s6_addr32[3]);
  32         sum += carry;
  33
  34         sum += (__force u32)daddr->s6_addr32[0];
  35         carry = (sum < (__force u32)daddr->s6_addr32[0]);
  36         sum += carry;
  37
  38         sum += (__force u32)daddr->s6_addr32[1];
  39         carry = (sum < (__force u32)daddr->s6_addr32[1]);
  40         sum += carry;
  41
  42         sum += (__force u32)daddr->s6_addr32[2];
  43         carry = (sum < (__force u32)daddr->s6_addr32[2]);
  44         sum += carry;
  45
  46         sum += (__force u32)daddr->s6_addr32[3];
  47         carry = (sum < (__force u32)daddr->s6_addr32[3]);
  48         sum += carry;
  49
  50         ulen = (__force u32)htonl((__u32) len);
  51         sum += ulen;
  52         carry = (sum < ulen);
  53         sum += carry;
  54
  55         uproto = (__force u32)htonl(proto);
  56         sum += uproto;
  57         carry = (sum < uproto);
  58         sum += carry;
  59
  60         return csum_fold((__force __wsum)sum);
  61 }
  62 EXPORT_SYMBOL(csum_ipv6_magic);
  63 #endif
  64
  65 int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto)
  66 {
  67         int err;
  68
  69         UDP_SKB_CB(skb)->partial_cov = 0;
  70         UDP_SKB_CB(skb)->cscov = skb->len;
  71
  72         if (proto == IPPROTO_UDPLITE) {
  73                 err = udplite_checksum_init(skb, uh);
  74                 if (err)
  75                         return err;
  76         }
  77
  78         if (uh->check == 0) {
  79                 /* RFC 2460 section 8.1 says that we SHOULD log
  80                    this error. Well, it is reasonable.
  81                  */
  82                 LIMIT_NETDEBUG(KERN_INFO "IPv6: udp checksum is 0\n");
  83                 return 1;
  84         }
  85         if (skb->ip_summed == CHECKSUM_COMPLETE &&
  86             !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr,
  87                              skb->len, proto, skb->csum))
  88                 skb->ip_summed = CHECKSUM_UNNECESSARY;
  89
  90         if (!skb_csum_unnecessary(skb))
  91                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
  92                                                          &ipv6_hdr(skb)->daddr,
  93                                                          skb->len, proto, 0));
  94
  95         return 0;
  96 }
  97 EXPORT_SYMBOL(udp6_csum_init);