diff options
Diffstat (limited to 'net')
-rw-r--r-- | net/net.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/net.c b/net/net.c index 2986924824b..37c5fb698e1 100644 --- a/net/net.c +++ b/net/net.c @@ -829,7 +829,10 @@ static ushort CDP_compute_csum(const uchar *buff, ushort len) } if (len) { leftover = (signed short)(*(const signed char *)buff); - /* * XXX CISCO SUCKS big time! (and blows too) */ + /* CISCO SUCKS big time! (and blows too): + * CDP uses the IP checksum algorithm with a twist; + * for the last byte it *sign* extends and sums. + */ result = (result & 0xffff0000) | ((result + leftover) & 0x0000ffff); } while (result >> 16) |