Hi,
In packet-udp.c, the following code is used to calculate UDP checksum:
/* Set up the fields of the pseudo-header. */
cksum_vec[0].ptr = pinfo->src.data;
cksum_vec[0].len = pinfo->src.len;
cksum_vec[1].ptr = pinfo->dst.data;
cksum_vec[1].len = pinfo->dst.len;
cksum_vec[2].ptr = (const guint8 *)&phdr;
switch (pinfo->src.type) {
case AT_IPv4:
phdr[0] = g_htonl((IP_PROTO_UDP<<16) + udph->uh_ulen);
cksum_vec[2].len = 4;
break;
case AT_IPv6:
phdr[0] = g_htonl(udph->uh_ulen);
phdr[1] = g_htonl(IP_PROTO_UDP);
cksum_vec[2].len = 8;
break;
default:
/* UDP runs only atop IPv4 and IPv6.... */
DISSECTOR_ASSERT_NOT_REACHED();
break;
}
cksum_vec[3].ptr = tvb_get_ptr(tvb, offset, udph->uh_ulen);
cksum_vec[3].len = udph->uh_ulen;
computed_cksum = in_cksum(&cksum_vec[0], 4);
Are
pinfo->src.data;
pinfo->src.len;
pinfo->dst.data;
pinfo->dst.len;
equivalent to
inet_ntoa(ip->ip_src);
4
inet_ntoa(ip->ip_dst);
4
respectively?
And does cksum_vec[3].ptr point to the beginning of the UDP header?
Thank you.
Regards,
Rayne
