int chksum6(struct pkt_ip6hdr_t *iph)
{
struct pkt_ip6pseudo_t hdr;
uint32_t sum = 0;
switch (iph->next_header) {
case ICMPv6_NEXT_HEADER:
{
struct pkt_icmphdr_t *icmp =
(struct pkt_icmphdr_t *)(((uint8_t *) iph) +
sizeof(struct
pkt_ip6hdr_t));
memcpy(hdr.src_addr, iph->src_addr, PKT_IPv6_ALEN);
memcpy(hdr.dst_addr, iph->dst_addr, PKT_IPv6_ALEN);
hdr.packet_len = htonl((uint32_t) ntohs(iph->data_len));
hdr.zero[0] = hdr.zero[1] = hdr.zero[2] = 0;
hdr.next_header = iph->next_header;
icmp->check = 0;
sum = in_cksum((uint16_t *) & hdr, sizeof(hdr));
sum +=
in_cksum((uint16_t *) icmp, ntohs(iph->data_len));
icmp->check = cksum_wrap(sum);
break;
}
case PKT_IP_PROTO_UDP:
{
struct pkt_udphdr_t *udphdr = (struct pkt_udphdr_t *)
(((uint8_t *) iph) + sizeof(struct pkt_ip6hdr_t));
uint16_t udplen = ntohs(udphdr->len);
memcpy(hdr.src_addr, iph->src_addr, PKT_IPv6_ALEN);
memcpy(hdr.dst_addr, iph->dst_addr, PKT_IPv6_ALEN);
hdr.packet_len = htonl((uint32_t) ntohs(iph->data_len));
hdr.zero[0] = hdr.zero[1] = hdr.zero[2] = 0;
hdr.next_header = iph->next_header;
udphdr->check = 0;
sum = in_cksum((uint16_t *) & hdr, sizeof(hdr));
sum += in_cksum((uint16_t *) udphdr, udplen);
udphdr->check = cksum_wrap(sum);
}
break;
case PKT_IP_PROTO_TCP:
{
struct pkt_tcphdr_t *tcphdr = (struct pkt_tcphdr_t *)
(((uint8_t *) iph) + sizeof(struct pkt_ip6hdr_t));
uint16_t tcplen = ntohs(iph->data_len);
memcpy(hdr.src_addr, iph->src_addr, PKT_IPv6_ALEN);
memcpy(hdr.dst_addr, iph->dst_addr, PKT_IPv6_ALEN);
hdr.packet_len = htonl((uint32_t) ntohs(iph->data_len));
hdr.zero[0] = hdr.zero[1] = hdr.zero[2] = 0;
hdr.next_header = iph->next_header;
tcphdr->check = 0;
sum = in_cksum((uint16_t *) & hdr, sizeof(hdr));
sum += in_cksum((uint16_t *) tcphdr, tcplen);
tcphdr->check = cksum_wrap(sum);
}
break;
}
return 0;
}
int chksum(struct pkt_iphdr_t *iph) {
uint16_t hlen;
uint32_t sum;
uint16_t len;
/* Only IPv4 currently */
if ((iph->version_ihl & 0xf0) != 0x40)
return -1;
/* Header length */
hlen = iph->version_ihl & 0x0f;
hlen <<= 2;
len = ntohs(iph->tot_len);
/* XXX: redundant */
if (hlen < PKT_IP_HLEN)
return -1;
#if(PKT_BUFFER < 65535)
if (len > PKT_BUFFER)
return -1; /* too long? */
#endif
if (len < hlen)
return -1; /* too short? */
switch(iph->protocol) {
case PKT_IP_PROTO_TCP:
{
struct pkt_tcphdr_t *tcph =
(struct pkt_tcphdr_t *)(((void *)iph) + hlen);
len -= hlen; /* length of tcp header + data */
tcph->check = 0;
sum = in_cksum(((uint16_t *)iph)+6/*saddr*/, 8);
sum += ntohs(IPPROTO_TCP + len);
sum += in_cksum((uint16_t *)tcph, len);
tcph->check = cksum_wrap(sum);
}
break;
case PKT_IP_PROTO_UDP:
{
struct pkt_udphdr_t *udph =
(struct pkt_udphdr_t *)(((void *)iph) + hlen);
uint16_t udplen = ntohs(udph->len);
if (udplen > len)
return -1;
udph->check = 0;
sum = in_cksum(((uint16_t *)iph)+6/*saddr*/, 8);
sum += ntohs(IPPROTO_UDP + udplen);
sum += in_cksum((uint16_t *)udph, udplen);
udph->check = cksum_wrap(sum);
}
break;
case PKT_IP_PROTO_ICMP:
{
struct pkt_icmphdr_t *icmph =
(struct pkt_icmphdr_t *)(((void *)iph) + hlen);
len -= hlen;
icmph->check = 0;
sum = in_cksum((uint16_t *)icmph, len);
icmph->check = cksum_wrap(sum);
}
break;
}
iph->check = 0;
sum = in_cksum((uint16_t *)iph, hlen);
iph->check = cksum_wrap(sum);
return 0;
}
