From 818f1f3e70dd4c8e6f8d59c617857be0fa0fce7c Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Wed, 9 Dec 2015 22:46:31 +0100 Subject: [PATCH] ipv6: add ipv6_addr_prefix_copy MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Alexey Kuznetsov Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy Acked-by: Łukasz Duda Acked-by: Hannes Frederic Sowa Acked-by: YOSHIFUJI Hideaki Acked-by: David S. Miller Reviewed-by: Stefan Schmidt Signed-off-by: Alexander Aring Signed-off-by: Marcel Holtmann --- include/net/ipv6.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 9a5c9f013784..6570f379aba2 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -401,6 +401,21 @@ 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)); + } +} + static inline void __ipv6_addr_set_half(__be32 *addr, __be32 wh, __be32 wl) { -- 2.20.1