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 <da...@davemloft.net>
Cc: Alexey Kuznetsov <kuz...@ms2.inr.ac.ru>
Cc: James Morris <jmor...@namei.org>
Cc: Hideaki YOSHIFUJI <yoshf...@linux-ipv6.org>
Cc: Patrick McHardy <ka...@trash.net>
Signed-off-by: Alexander Aring <alex.ar...@gmail.com>
---
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));
+ }
+}
+
static inline void __ipv6_addr_set_half(__be32 *addr,
__be32 wh, __be32 wl)
{
--
2.6.1
--
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