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Have separate routines to dissect an FCS and TI CC24xx metadata. 

Those fields have nothing in common.

Change-Id: Ida29ce36a8a3e311b58a900a5631e314ebc39662
Reviewed-on: https://code.wireshark.org/review/32279
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2019-02-28 16:19:06 -08:00
parent 371c71ac1e
commit 8ecb42ae0d
1 changed files with 68 additions and 27 deletions
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95
epan/dissectors/packet-ieee802154.c
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@ -351,7 +351,8 @@ static int dissect_ieee802154_cc24xx (tvbuff_t *, packet_info *, proto_tre
static int dissect_ieee802154_tap (tvbuff_t *, packet_info *, proto_tree *, void *);
static tvbuff_t *dissect_zboss_specific (tvbuff_t *, packet_info *, proto_tree *);
static void dissect_ieee802154_common (tvbuff_t *, packet_info *, proto_tree *, guint, guint);
static void ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, guint, gboolean is_cc24xx, gboolean fcs_ok);
static void ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, guint fcs_len, gboolean fcs_ok);
static void ieee802154_dissect_cc24xx_metadata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, gboolean fcs_ok);
static ieee802154_fcs_type_t dissect_ieee802154_tap_tlvs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
/* Information Elements */
@ -2034,8 +2035,12 @@ dissect_ieee802154_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
}
}
if (fcs_present)
ieee802154_dissect_fcs(tvb, pinfo, ieee802154_tree, fcs_len, options & DISSECT_IEEE802154_OPTION_CC24xx, fcs_ok);
if (fcs_present) {
if (options & DISSECT_IEEE802154_OPTION_CC24xx)
ieee802154_dissect_cc24xx_metadata(tvb, pinfo, ieee802154_tree, fcs_ok);
else
ieee802154_dissect_fcs(tvb, pinfo, ieee802154_tree, fcs_len, fcs_ok);
}
if (ieee802154_ack_tracking && fcs_ok && (packet->ack_request || packet->frame_type == IEEE802154_FCF_ACK)) {
address src_addr;
@ -2767,18 +2772,17 @@ guint ieee802154_dissect_frame_payload(tvbuff_t *tvb, packet_info *pinfo, proto_
}
/**
* Dissect the FCS, or TI CC24xx metadata, at the end of the frame.
* Dissect the FCS at the end of the frame.
* That is only displayed if the included length of the tvb encompasses it.
*
* @param tvb the 802.15.4 frame tvb
* @param pinfo pointer to packet information fields
* @param ieee802154_tree the 802.15.4 protocol tree
* @param fcs_len length of the FCS/metadata field
* @param is_cc24xx indicate if it's TI CC24xx-format metadata
* @param fcs_len length of the FCS field
* @param fcs_ok set to FALSE to indicate FCS verification failed
*/
static void
ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, guint fcs_len, gboolean is_cc24xx, gboolean fcs_ok)
ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, guint fcs_len, gboolean fcs_ok)
{
proto_item *ti;
/* The FCS should be the last bytes of the reported packet. */
@ -2789,32 +2793,19 @@ ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154
* is too short for an FCS don't make a fuss.
*/
if (fcs_len && tvb_bytes_exist(tvb, offset, fcs_len) && (ieee802154_tree)) {
proto_tree *field_tree;
if (fcs_len == 2) {
guint16 fcs = tvb_get_letohs(tvb, offset);
/* Display the FCS or metadata, depending on expected format */
if (is_cc24xx) {
/* Create a subtree for the FCS. */
field_tree = proto_tree_add_subtree_format(ieee802154_tree, tvb, offset, 2, ett_ieee802154_fcs, NULL,
"TI CC24xx-format metadata: FCS %s", (fcs_ok) ? "OK" : "Bad");
/* Display metadata contents. */
proto_tree_add_boolean(field_tree, hf_ieee802154_fcs_ok, tvb, offset, 1, (guint32) (fcs & IEEE802154_CC24xx_CRC_OK));
proto_tree_add_int(field_tree, hf_ieee802154_rssi, tvb, offset++, 1, (gint8) (fcs & IEEE802154_CC24xx_RSSI));
proto_tree_add_uint(field_tree, hf_ieee802154_correlation, tvb, offset, 1, (guint8) ((fcs & IEEE802154_CC24xx_CORRELATION) >> 8));
ti = proto_tree_add_uint(ieee802154_tree, hf_ieee802154_fcs, tvb, offset, 2, fcs);
if (fcs_ok) {
proto_item_append_text(ti, " (Correct)");
}
else {
ti = proto_tree_add_uint(ieee802154_tree, hf_ieee802154_fcs, tvb, offset, 2, fcs);
if (fcs_ok) {
proto_item_append_text(ti, " (Correct)");
}
else {
proto_item_append_text(ti, " (Incorrect, expected FCS=0x%04x)", ieee802154_crc_tvb(tvb, offset));
}
/* To Help with filtering, add the fcs_ok field to the tree. */
ti = proto_tree_add_boolean(ieee802154_tree, hf_ieee802154_fcs_ok, tvb, offset, 2, (guint32) fcs_ok);
PROTO_ITEM_SET_HIDDEN(ti);
proto_item_append_text(ti, " (Incorrect, expected FCS=0x%04x)", ieee802154_crc_tvb(tvb, offset));
}
/* To Help with filtering, add the fcs_ok field to the tree. */
ti = proto_tree_add_boolean(ieee802154_tree, hf_ieee802154_fcs_ok, tvb, offset, 2, (guint32) fcs_ok);
PROTO_ITEM_SET_HIDDEN(ti);
}
else {
guint32 fcs = tvb_get_letohl(tvb, offset);
@ -2849,6 +2840,56 @@ ieee802154_dissect_fcs(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154
}
} /* ieee802154_dissect_fcs */
/**
* Dissect the TI CC24xx metadata at the end of the frame.
* That is only displayed if the included length of the tvb encompasses it.
*
* @param tvb the 802.15.4 frame tvb
* @param pinfo pointer to packet information fields
* @param ieee802154_tree the 802.15.4 protocol tree
* @param fcs_ok set to FALSE to indicate FCS verification failed
*/
static void
ieee802154_dissect_cc24xx_metadata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ieee802154_tree, gboolean fcs_ok)
{
proto_item *ti;
/* The metadata should be the last 2 bytes of the reported packet. */
guint offset = tvb_reported_length(tvb)-2;
/* Dissect the metadata only if it exists (captures which don't or can't get the
* metadata will simply truncate the packet to omit it, but should still set the
* reported length to cover the original packet length), so if the snapshot
* is too short for the metadata don't make a fuss.
*/
if (tvb_bytes_exist(tvb, offset, 2) && (ieee802154_tree)) {
proto_tree *field_tree;
guint16 metadata = tvb_get_letohs(tvb, offset);
/* Create a subtree for the metadata. */
field_tree = proto_tree_add_subtree_format(ieee802154_tree, tvb, offset, 2, ett_ieee802154_fcs, NULL,
"TI CC24xx-format metadata: FCS %s", (fcs_ok) ? "OK" : "Bad");
/* Display metadata contents. */
proto_tree_add_boolean(field_tree, hf_ieee802154_fcs_ok, tvb, offset, 1, (guint32) (metadata & IEEE802154_CC24xx_CRC_OK));
proto_tree_add_int(field_tree, hf_ieee802154_rssi, tvb, offset++, 1, (gint8) (metadata & IEEE802154_CC24xx_RSSI));
proto_tree_add_uint(field_tree, hf_ieee802154_correlation, tvb, offset, 1, (guint8) ((metadata & IEEE802154_CC24xx_CORRELATION) >> 8));
}
else if (ieee802154_tree) {
/* Even if the FCS isn't present, add the fcs_ok field to the tree to
* help with filter. Be sure not to make it visible though.
*/
ti = proto_tree_add_boolean_format_value(ieee802154_tree, hf_ieee802154_fcs_ok, tvb, offset, 2, fcs_ok, "Unknown");
PROTO_ITEM_SET_HIDDEN(ti);
}
/* If the CRC is invalid, make a note of it in the info column. */
if (!fcs_ok) {
col_append_str(pinfo->cinfo, COL_INFO, ", Bad FCS");
proto_item_append_text(proto_tree_get_parent(ieee802154_tree), ", Bad FCS");
/* Flag packet as having a bad crc. */
expert_add_info(pinfo, proto_tree_get_parent(ieee802154_tree), &ei_ieee802154_fcs);
}
} /* ieee802154_dissect_cc24xx_metadata */
static void
dissect_ieee802154_tap_sun_phy(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, guint length)
{