On Sun, Nov 29, 2015, at 12:34, Alexander Aring wrote:
> This patch adds a static inline function ipv6_addr_prefix_copy which
> copies a ipv6 address prefix(argument pfx) into the ipv6 address prefix.
> The prefix len is given by plen as bits. This function mainly based on
> ipv6_addr_prefix which copies one address prefix from address into a new
> ipv6 address destination and zero all other address bits.
>
> The difference is that ipv6_addr_prefix_copy don't get a prefix from an
> ipv6 address, it sets a prefix to an ipv6 address with keeping other
> address bits. The use case is for context based address compression
> inside 6LoWPAN IPHC header which keeping ipv6 prefixes inside a context
> table to lookup address-bits without sending them.
>
> Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
> Cc: James Morris <jmorris@xxxxxxxxx>
> Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>
> Cc: Patrick McHardy <kaber@xxxxxxxxx>
> Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx>
> ---
> include/net/ipv6.h | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index e1a10b0..cd3881e6 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -382,6 +382,21 @@ static inline void ipv6_addr_prefix(struct in6_addr
> *pfx,
> pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
> }
>
> +static inline void ipv6_addr_prefix_copy(struct in6_addr *addr,
> + const struct in6_addr *pfx,
> + int plen)
> +{
> + /* caller must guarantee 0 <= plen <= 128 */
> + int o = plen >> 3,
> + b = plen & 0x7;
> +
> + memcpy(addr->s6_addr, pfx, o);
> + if (b != 0) {
> + addr->s6_addr[o] &= ~(0xff00 >> b);
> + addr->s6_addr[o] |= (pfx->s6_addr[o] & (0xff00 >> b));
> + }
> +}
> +
Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
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