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Tx MCS set is not interpreted properly in WLAN beacon frame. Bug 8894 (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=8894) 

#BACKPORT

svn path=/trunk/; revision=53670
This commit is contained in:
Michael Mann 2013-11-30 01:35:03 +00:00
parent 6d3d1556dc
commit e1532f39ec
1 changed files with 58 additions and 4 deletions
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62
epan/dissectors/packet-ieee80211.c
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@ -2302,6 +2302,7 @@ static const value_string mcsset_tx_max_spatial_streams_flags[] = {
{0x01, "2 spatial streams"},
{0x02, "3 spatial streams"},
{0x03, "4 spatial streams"},
{0x04, "TX MCS Set Not Defined"},
{0x00, NULL}
};
@ -9715,7 +9716,10 @@ dissect_mcs_set(proto_tree *tree, tvbuff_t *tvb, int offset, gboolean basic, gbo
{
proto_item *ti;
proto_tree *mcs_tree, *bit_tree;
guint8 rx_nss, tx_nss; /* 0-4 for HT and 0-8 for VHT*/
guint32 value_mcs_0_31, value_mcs_32_52, value_mcs_53_76;
guint16 tx_mcs_set;
rx_nss = tx_nss = 8;
/* 16 byte Supported MCS set */
if (vs)
{
@ -9733,31 +9737,81 @@ dissect_mcs_set(proto_tree *tree, tvbuff_t *tvb, int offset, gboolean basic, gbo
bit_tree = proto_item_add_subtree(ti, ett_mcsbit_tree);
/* Bits 0 - 31 */
value_mcs_0_31 = tvb_get_letohl(tvb, offset);
/* Handle all zeroes/ff's case..*/
if (value_mcs_0_31 != 0x0)
{
if (!(value_mcs_0_31 & (0xffffff00)))
rx_nss = 0 ; /* 1 spatial stream*/
else if (!(value_mcs_0_31 & (0xffff0000)))
rx_nss = 1 ; /*2 spatial streams*/
else if (!(value_mcs_0_31 & (0xff000000)))
rx_nss = 2 ;/*3 spatial streams*/
else
rx_nss = 3 ;/*4 spatial streams*/
}
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_0to7, tvb, offset, 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_8to15, tvb, offset, 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_16to23, tvb, offset, 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_24to31, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
/* Should be we check UEQM Supported?*/
/* Bits 32 - 52 */
value_mcs_32_52 = tvb_get_letohl(tvb, offset);
if (!(value_mcs_32_52 & ~(0x00000001)))
rx_nss = rx_nss ; /* 1 spatial stream*/
else if (!(value_mcs_32_52 & ~(0x00007e)))
rx_nss = MAX(1,rx_nss) ; /*2 spatial streams*/
else if (!(value_mcs_32_52 & ~(0x1ffff80)))
rx_nss = MAX(2,rx_nss); /*3 spatial streams*/
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_32, tvb, offset , 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_33to38, tvb, offset, 4, ENC_LITTLE_ENDIAN);
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_39to52, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 2;
/* Bits 53 - 76 */
value_mcs_53_76 = tvb_get_letohl(tvb, offset);
if ((value_mcs_53_76 & (0x1fffffe0)))
rx_nss = MAX(3,rx_nss) ; /* 4 spatial streams*/
proto_tree_add_item(bit_tree, hf_ieee80211_mcsset_rx_bitmask_53to76, tvb, offset, 4, ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_highest_data_rate, tvb, offset, 2, ENC_LITTLE_ENDIAN);
offset += 2;
/* Follow table 8-126 from 802.11-2012 */
tx_mcs_set = tvb_get_letohs(tvb,offset);
if (!(tx_mcs_set & 0x0001) && !(tx_mcs_set & 0x0002))
{
/* TX MCS Set is not defined
* so there is no interpretation for Max Tx Spatial Streams
*/
tx_nss = 4; /* Not Defined*/
}
if ((tx_mcs_set & 0x0001) && !(tx_mcs_set & 0x0002))
{
/* TX MCS Set is defined to be equal to Rx MCS Set
* So, get the Max Spatial Streams from Rx
* MCS set
*/
tx_nss = rx_nss;
}
proto_item_append_text(ti, ": %s",val_to_str(rx_nss,mcsset_tx_max_spatial_streams_flags,"Reserved:%d" ) );
proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_tx_mcs_set_defined, tvb, offset, 1,
ENC_LITTLE_ENDIAN);
proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_tx_rx_mcs_set_not_equal, tvb, offset, 1,
ENC_LITTLE_ENDIAN);
proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_tx_max_spatial_streams, tvb, offset, 1,
ti = proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_tx_max_spatial_streams, tvb, offset, 1,
ENC_LITTLE_ENDIAN);
proto_item_append_text(ti, ", %s",val_to_str(tx_nss,mcsset_tx_max_spatial_streams_flags,"Reserved:%d" ) );
proto_tree_add_item(mcs_tree, hf_ieee80211_mcsset_tx_unequal_modulation, tvb, offset, 1,
ENC_LITTLE_ENDIAN);
offset += 1;
@ -18232,8 +18286,8 @@ proto_register_ieee80211 (void)
NULL, HFILL }},
{&hf_ieee80211_mcsset_tx_max_spatial_streams,
{"Max Tximum Number of Spatial Streams Supported", "wlan_mgt.ht.mcsset.txmaxss",
FT_UINT16, BASE_HEX, VALS(mcsset_tx_max_spatial_streams_flags) , 0x000c,
{"Maximum Number of Tx Spatial Streams Supported", "wlan_mgt.ht.mcsset.txmaxss",
FT_UINT16, BASE_HEX, 0 , 0x000c,
NULL, HFILL }},
{&hf_ieee80211_mcsset_tx_unequal_modulation,