diff options
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/ipv6.h | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 65ec86678a0..98661fa4fc7 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -341,6 +341,54 @@ static inline int ipv6_addr_any(const struct in6_addr *a) } /* + * find the first different bit between two addresses + * length of address must be a multiple of 32bits + */ +static inline int __ipv6_addr_diff(const void *token1, const void *token2, int addrlen) +{ + const __u32 *a1 = token1, *a2 = token2; + int i; + + addrlen >>= 2; + + for (i = 0; i < addrlen; i++) { + __u32 xb = a1[i] ^ a2[i]; + if (xb) { + int j = 31; + + xb = ntohl(xb); + while ((xb & (1 << j)) == 0) + j--; + + return (i * 32 + 31 - j); + } + } + + /* + * we should *never* get to this point since that + * would mean the addrs are equal + * + * However, we do get to it 8) And exacly, when + * addresses are equal 8) + * + * ip route add 1111::/128 via ... + * ip route add 1111::/64 via ... + * and we are here. + * + * Ideally, this function should stop comparison + * at prefix length. It does not, but it is still OK, + * if returned value is greater than prefix length. + * --ANK (980803) + */ + return (addrlen << 5); +} + +static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_addr *a2) +{ + return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr)); +} + +/* * Prototypes exported by ipv6 */ |