2016-02-16 14:27:33

by Lorenzo Bianconi

[permalink] [raw]
Subject: [PATCH] mac80211: parse VHT info in injected frames

Add VHT radiotap parsing support to ieee80211_parse_tx_radiotap().
That capability has been tested using a d-link dir-860l rev b1 running
OpenWrt trunk and mt76 driver

Signed-off-by: Lorenzo Bianconi <[email protected]>
---
Documentation/networking/mac80211-injection.txt | 10 ++++++++
net/mac80211/tx.c | 31 +++++++++++++++++++++++++
2 files changed, 41 insertions(+)

diff --git a/Documentation/networking/mac80211-injection.txt b/Documentation/networking/mac80211-injection.txt
index ec8f934..ef57cc0 100644
--- a/Documentation/networking/mac80211-injection.txt
+++ b/Documentation/networking/mac80211-injection.txt
@@ -45,6 +45,16 @@ radiotap headers and used to control injection:
number of retries when either IEEE80211_RADIOTAP_RATE or
IEEE80211_RADIOTAP_MCS was used

+ * IEEE80211_RADIOTAP_VHT
+
+ VHT rate for the transmission (only for devices without own rate control).
+ Also some flags are parsed
+
+ IEEE80211_TX_RC_SHORT_GI: use short guard interval
+ IEEE80211_TX_RC_40_MHZ_WIDTH: send in HT40 mode
+ IEEE80211_TX_RC_80_MHZ_WIDTH: send in HT80 mode
+ IEEE80211_TX_RC_160_MHZ_WIDTH: send in HT160 mode
+
The injection code can also skip all other currently defined radiotap fields
facilitating replay of captured radiotap headers directly.

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 7bb67fa..17db889 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1692,6 +1692,8 @@ static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local,
u8 rate_retries = 0;
u16 rate_flags = 0;
u8 mcs_known, mcs_flags;
+ u16 vht_known;
+ u8 vht_mcs = 0, vht_nss = 0;
int i;

info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
@@ -1772,6 +1774,32 @@ static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local,
rate_flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
break;

+ case IEEE80211_RADIOTAP_VHT:
+ vht_known = get_unaligned_le16(iterator.this_arg);
+ rate_found = true;
+
+ rate_flags = IEEE80211_TX_RC_VHT_MCS;
+ if ((vht_known & IEEE80211_RADIOTAP_VHT_KNOWN_GI) &&
+ (iterator.this_arg[2] &
+ IEEE80211_RADIOTAP_VHT_FLAG_SGI))
+ rate_flags |= IEEE80211_TX_RC_SHORT_GI;
+ if (vht_known &
+ IEEE80211_RADIOTAP_VHT_KNOWN_BANDWIDTH) {
+ if (iterator.this_arg[3] == 1)
+ rate_flags |=
+ IEEE80211_TX_RC_40_MHZ_WIDTH;
+ else if (iterator.this_arg[3] == 4)
+ rate_flags |=
+ IEEE80211_TX_RC_80_MHZ_WIDTH;
+ else if (iterator.this_arg[3] == 11)
+ rate_flags |=
+ IEEE80211_TX_RC_160_MHZ_WIDTH;
+ }
+
+ vht_mcs = iterator.this_arg[4] >> 4;
+ vht_nss = iterator.this_arg[4] & 0xF;
+ break;
+
/*
* Please update the file
* Documentation/networking/mac80211-injection.txt
@@ -1797,6 +1825,9 @@ static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local,

if (rate_flags & IEEE80211_TX_RC_MCS) {
info->control.rates[0].idx = rate;
+ } else if (rate_flags & IEEE80211_TX_RC_VHT_MCS) {
+ ieee80211_rate_set_vht(info->control.rates, vht_mcs,
+ vht_nss);
} else {
for (i = 0; i < sband->n_bitrates; i++) {
if (rate * 5 != sband->bitrates[i].bitrate)
--
2.5.0