n -= sizeof(*ip);
udp = (struct udphdr *)(ip + 1);
- if (n < sizeof(udp) || udp->uh_sport != st->me.sin.sin_port ||
+ if (n < sizeof(*udp) || udp->uh_sport != st->me.sin.sin_port ||
udp->uh_dport != st->a.sin.sin_port)
goto skip_icmp;
n -= sizeof(*udp);