static void
dissect_stt_checksum(tvbuff_t *tvb, packet_info *pinfo, proto_tree *stt_tree)
{
gboolean can_checksum = !pinfo->fragmented &&
tvb_bytes_exist(tvb, 0, tvb_reported_length(tvb));
if (can_checksum && pref_check_checksum) {
vec_t cksum_vec[4];
guint32 phdr[2];
/* Set up the fields of the pseudo-header. */
SET_CKSUM_VEC_PTR(cksum_vec[0], (const guint8 *)pinfo->src.data,
pinfo->src.len);
SET_CKSUM_VEC_PTR(cksum_vec[1], (const guint8 *)pinfo->dst.data,
pinfo->dst.len);
switch (pinfo->src.type) {
case AT_IPv4:
phdr[0] = g_htonl((IP_PROTO_TCP<<16) + tvb_reported_length(tvb));
SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *)phdr, 4);
break;
case AT_IPv6:
phdr[0] = g_htonl(tvb_reported_length(tvb));
phdr[1] = g_htonl(IP_PROTO_TCP);
SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *)phdr, 8);
break;
default:
/* STT runs only atop IPv4 and IPv6.... */
DISSECTOR_ASSERT_NOT_REACHED();
break;
}
SET_CKSUM_VEC_TVB(cksum_vec[3], tvb, 0, tvb_reported_length(tvb));
proto_tree_add_checksum(stt_tree, tvb, 16, hf_stt_checksum, hf_stt_checksum_status, &ei_stt_checksum_bad, pinfo,
in_cksum(cksum_vec, 4), ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
} else {
proto_tree_add_checksum(stt_tree, tvb, 16, hf_stt_checksum, hf_stt_checksum_status, &ei_stt_checksum_bad, pinfo,
0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
}
}
static void
dissect_stt_checksum(tvbuff_t *tvb, packet_info *pinfo, proto_tree *stt_tree)
{
proto_tree *checksum_tree;
proto_item *item;
guint16 checksum = tvb_get_ntohs(tvb, 16);
gboolean can_checksum;
guint16 computed_cksum;
gboolean checksum_good = FALSE, checksum_bad = FALSE;
item = proto_tree_add_uint_format_value(stt_tree, hf_stt_checksum,
tvb, 16, 2, checksum,
"0x%04x", checksum);
can_checksum = !pinfo->fragmented &&
tvb_bytes_exist(tvb, 0, tvb_reported_length(tvb));
if (can_checksum && pref_check_checksum) {
vec_t cksum_vec[4];
guint32 phdr[2];
/* Set up the fields of the pseudo-header. */
SET_CKSUM_VEC_PTR(cksum_vec[0], (const guint8 *)pinfo->src.data,
pinfo->src.len);
SET_CKSUM_VEC_PTR(cksum_vec[1], (const guint8 *)pinfo->dst.data,
pinfo->dst.len);
switch (pinfo->src.type) {
case AT_IPv4:
phdr[0] = g_htonl((IP_PROTO_TCP<<16) + tvb_reported_length(tvb));
SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *)phdr, 4);
break;
case AT_IPv6:
phdr[0] = g_htonl(tvb_reported_length(tvb));
phdr[1] = g_htonl(IP_PROTO_TCP);
SET_CKSUM_VEC_PTR(cksum_vec[2], (const guint8 *)phdr, 8);
break;
default:
/* STT runs only atop IPv4 and IPv6.... */
DISSECTOR_ASSERT_NOT_REACHED();
break;
}
SET_CKSUM_VEC_TVB(cksum_vec[3], tvb, 0, tvb_reported_length(tvb));
computed_cksum = in_cksum(cksum_vec, 4);
checksum_good = (computed_cksum == 0);
checksum_bad = !checksum_good;
if (checksum_good) {
proto_item_append_text(item, " [correct]");
} else if (checksum_bad) {
guint16 expected_cksum = in_cksum_shouldbe(checksum, computed_cksum);
proto_item_append_text(item, " [incorrect, should be 0x%04x (maybe caused by \"TCP checksum offload\"?)]",
expected_cksum);
expert_add_info(pinfo, item, &ei_stt_checksum_bad);
checksum = expected_cksum;
}
} else if (pref_check_checksum) {
proto_item_append_text(item, " [unchecked, not all data available]");
} else {
proto_item_append_text(item, " [validation disabled]");
}
checksum_tree = proto_item_add_subtree(item, ett_stt_checksum);
if (checksum_good || checksum_bad) {
item = proto_tree_add_uint(checksum_tree, hf_stt_checksum_calculated,
tvb, 16, 2, checksum);
PROTO_ITEM_SET_GENERATED(item);
}
item = proto_tree_add_boolean(checksum_tree, hf_stt_checksum_good, tvb,
16, 2, checksum_good);
PROTO_ITEM_SET_GENERATED(item);
item = proto_tree_add_boolean(checksum_tree, hf_stt_checksum_bad, tvb,
16, 2, checksum_bad);
PROTO_ITEM_SET_GENERATED(item);
}
