wrapsum
ip.ip_sum = wrapsum(checksum((unsigned char *)&ip, sizeof(ip), 0));
udp.uh_sum = wrapsum(checksum(data, len, checksum((unsigned char *)&udp,
if (wrapsum(checksum(buf + bufix, ip_len, 0)) != 0) {
sum = wrapsum(checksum(data, len,
u_int32_t wrapsum(u_int32_t);
udp.uh_sum = wrapsum(
udp.uh_sum = wrapsum(
ip.ip_sum = wrapsum(checksum(&ip, sizeof(ip), 0));
udp.uh_sum = wrapsum(
udp.uh_sum = wrapsum(