Hello.
On 25/11/15 19:17, Alexander Aring wrote:
On Wed, Nov 25, 2015 at 05:42:52PM +0100, Stefan Schmidt wrote:
Hello.
On 17/11/15 23:33, Alexander Aring wrote:
This patch adds a static inline function ipv6_addr_prefix_cpy 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_cpy 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..9d38fc2 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_cpy(struct in6_addr *addr,
+ const struct in6_addr *pfx,
+ int plen)
+{
Naming it ipv6_addr_prefix_cop, as Sergei suggested, would be easier to
read.
ok.
+ /* caller must guarantee 0 <= plen <= 128 */
+ int o = plen >> 3,
+ b = plen & 0x7;
+
Any reason you are not doing the memset here before memcpy like it is done
in ipv6_addr_prefi()?
ipv6_addr_prefix is more a "getter" for a prefix from an address. The
destination address (which should be the result) will memset the whole
address before copy the prefix from address to it.
Ah, right. Missed that part.
THe ipv6_addr_prefix_copy will set a prefix given by second parameter
pfx and set the prefix to the address (given by first parameter).
Maybe the ipv6_addr_prefix could call:
1. memset(pfx, sizeof...)
2. ipv6_addr_prefix_copy(pfx, addr, plen);
but ipv6_addr_prefix_copy need to care about other bits which are set at
destination address, if (plen/8 != 0). I don't want to touch
ipv6_addr_prefix function and slow-down some mechanism.
No need to change this from my side. I just missed the memset being
handled in the destination address.
With the name change to _copy you can add my
Reviewed-by: Stefan Schmidt <stefan@xxxxxxxxxxxxxxx>
regards
Stefan Schmidt
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