2011-06-23 17:26:34

by Paul Stewart

Subject: [PATCH] mac80211: Drop DS Channel PARAM in directed probe

Do not send DS Channel parameter for directed probe requests
in order to maximize the chance that we get a response. Some
badly-behaved APs don't respond when this parameter is included.

Signed-off-by: Paul Stewart <[email protected]>
---
net/mac80211/ieee80211_i.h | 6 ++++--
net/mac80211/mlme.c | 5 +++--
net/mac80211/scan.c | 3 ++-
net/mac80211/util.c | 21 ++++++++++++++++-----
net/mac80211/work.c | 2 +-
5 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 090b0ec..25c15cc 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1350,10 +1350,12 @@ int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
struct sk_buff *ieee80211_build_probe_req(struct ieee80211_sub_if_data *sdata,
u8 *dst,
const u8 *ssid, size_t ssid_len,
- const u8 *ie, size_t ie_len);
+ const u8 *ie, size_t ie_len,
+ bool directed);
void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
const u8 *ssid, size_t ssid_len,
- const u8 *ie, size_t ie_len);
+ const u8 *ie, size_t ie_len,
+ bool directed);

void ieee80211_sta_def_wmm_params(struct ieee80211_sub_if_data *sdata,
const size_t supp_rates_len,
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index faca503..0f6052f 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1204,7 +1204,8 @@ static void ieee80211_mgd_probe_ap_send(struct ieee80211_sub_if_data *sdata)
ieee80211_send_nullfunc(sdata->local, sdata, 0);
} else {
ssid = ieee80211_bss_get_ie(ifmgd->associated, WLAN_EID_SSID);
- ieee80211_send_probe_req(sdata, dst, ssid + 2, ssid[1], NULL, 0);
+ ieee80211_send_probe_req(sdata, dst, ssid + 2, ssid[1], NULL, 0,
+ true);
}

ifmgd->probe_send_count++;
@@ -1289,7 +1290,7 @@ struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,

ssid = ieee80211_bss_get_ie(ifmgd->associated, WLAN_EID_SSID);
skb = ieee80211_build_probe_req(sdata, ifmgd->associated->bssid,
- ssid + 2, ssid[1], NULL, 0);
+ ssid + 2, ssid[1], NULL, 0, true);

return skb;
}
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 1758b46..a97eed0 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -658,7 +658,8 @@ static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
sdata, NULL,
local->scan_req->ssids[i].ssid,
local->scan_req->ssids[i].ssid_len,
- local->scan_req->ie, local->scan_req->ie_len);
+ local->scan_req->ie, local->scan_req->ie_len,
+ false);

/*
* After sending probe requests, wait for probe responses
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 05e3fb8..652e569 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1018,7 +1018,8 @@ int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
struct sk_buff *ieee80211_build_probe_req(struct ieee80211_sub_if_data *sdata,
u8 *dst,
const u8 *ssid, size_t ssid_len,
- const u8 *ie, size_t ie_len)
+ const u8 *ie, size_t ie_len,
+ bool directed)
{
struct ieee80211_local *local = sdata->local;
struct sk_buff *skb;
@@ -1035,8 +1036,16 @@ struct sk_buff *ieee80211_build_probe_req(struct ieee80211_sub_if_data *sdata,
return NULL;
}

- chan = ieee80211_frequency_to_channel(
- local->hw.conf.channel->center_freq);
+ /*
+ * Do not send DS Channel parameter for directed probe requests
+ * in order to maximize the chance that we get a response. Some
+ * badly-behaved APs don't respond when this parameter is included.
+ */
+ if (directed)
+ chan = 0;
+ else
+ chan = ieee80211_frequency_to_channel(
+ local->hw.conf.channel->center_freq);

buf_len = ieee80211_build_preq_ies(local, buf, ie, ie_len,
local->hw.conf.channel->band,
@@ -1062,11 +1071,13 @@ struct sk_buff *ieee80211_build_probe_req(struct ieee80211_sub_if_data *sdata,

void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
const u8 *ssid, size_t ssid_len,
- const u8 *ie, size_t ie_len)
+ const u8 *ie, size_t ie_len,
+ bool directed)
{
struct sk_buff *skb;

- skb = ieee80211_build_probe_req(sdata, dst, ssid, ssid_len, ie, ie_len);
+ skb = ieee80211_build_probe_req(sdata, dst, ssid, ssid_len, ie, ie_len,
+ directed);
if (skb)
ieee80211_tx_skb(sdata, skb);
}
diff --git a/net/mac80211/work.c b/net/mac80211/work.c
index d2e7f0e..edf8583 100644
--- a/net/mac80211/work.c
+++ b/net/mac80211/work.c
@@ -450,7 +450,7 @@ ieee80211_direct_probe(struct ieee80211_work *wk)
* will not answer to direct packet in unassociated state.
*/
ieee80211_send_probe_req(sdata, NULL, wk->probe_auth.ssid,
- wk->probe_auth.ssid_len, NULL, 0);
+ wk->probe_auth.ssid_len, NULL, 0, true);

wk->timeout = jiffies + IEEE80211_AUTH_TIMEOUT;
run_again(local, wk->timeout);
--
1.7.3.1

2011-06-27 12:40:04

by Johannes Berg

Subject: Re: [PATCH] mac80211: Drop DS Channel PARAM in directed probe

On Thu, 2011-06-23 at 09:00 -0800, Paul Stewart wrote:
> Do not send DS Channel parameter for directed probe requests
> in order to maximize the chance that we get a response. Some
> badly-behaved APs don't respond when this parameter is included.
>
> Signed-off-by: Paul Stewart <[email protected]>

Reviewed-by: Johannes Berg <[email protected]>

Thanks Paul, this is a good workaround, hopefully those broken devices
won't ever support hidden SSIDs.

johannes