net/icmpv6: Fix icmpv6 checksum calculation in icmpv6_reply
The second param of icmpv6_chksum is `iplen`, which indicates `The size of the IPv6 header`.
@@ -139,7 +139,7 @@ void icmpv6_reply(FAR struct net_driver_s *dev, int type, int code, int data)
/* Calculate the ICMPv6 checksum over the ICMPv6 header and payload. */
icmpv6->chksum = 0;
- icmpv6->chksum = ~icmpv6_chksum(dev, datalen + sizeof(*icmpv6));
+ icmpv6->chksum = ~icmpv6_chksum(dev, IPv6_HDRLEN);
if (icmpv6->chksum == 0)
{
icmpv6->chksum = 0xffff;
