ICMP_ECHO_LEN
icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
if (data + sizeof(*eth) + sizeof(*iph) + ICMP_ECHO_LEN > data_end)
if (bpf_ntohs(iph->tot_len) - sizeof(*iph) != ICMP_ECHO_LEN)