Re: [PATCHv3] mac80211: Add function to get probe request template for current AP

[Johannes Berg <johannes@sipsolutions.net>]

On Thu, 2010-11-11 at 08:50 +0200, juuso.oikarinen@nokia.com wrote:
> From: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> 
> Chipsets with hardware based connection monitoring need to autonomically
> send directed probe-request frames to the AP (in the event of beacon loss,
> for example.)
> 
> For the hardware to be able to do this, it requires a template for the frame
> to transmit to the AP, filled in with the BSSID and SSID of the AP, but also
> the supported rate IE's.
> 
> This patch adds a function to mac80211, which allows the hardware driver to
> fetch this template after association, so it can be configured to the hardware.
> 
> Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> ---
> v2: Add more documentation to the ieee80211_ap_probereq_get function
> v3: Added some honesty to the documentation of ieee80211_ap_probereq_get

:-)

Acked-by: Johannes Berg <johannes@sipsolutions.net>

>  include/net/mac80211.h     |   15 +++++++++++++++
>  net/mac80211/ieee80211_i.h |    4 ++++
>  net/mac80211/mlme.c        |   24 ++++++++++++++++++++++++
>  net/mac80211/util.c        |   23 ++++++++++++++++++-----
>  4 files changed, 61 insertions(+), 5 deletions(-)
> 
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 9fdf982..773694b 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -2501,6 +2501,21 @@ void ieee80211_sta_block_awake(struct ieee80211_hw *hw,
>  			       struct ieee80211_sta *pubsta, bool block);
>  
>  /**
> + * ieee80211_ap_probereq_get - retrieve a Probe Request template
> + * @hw: pointer obtained from ieee80211_alloc_hw().
> + * @vif: &struct ieee80211_vif pointer from the add_interface callback.
> + *
> + * Creates a Probe Request template which can, for example, be uploaded to
> + * hardware. The template is filled with bssid, ssid and supported rate
> + * information. This function must only be called from within the
> + * .bss_info_changed callback function and only in managed mode. The function
> + * is only useful when the interface is associated, otherwise it will return
> + * NULL.
> + */
> +struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,
> +					  struct ieee80211_vif *vif);
> +
> +/**
>   * ieee80211_beacon_loss - inform hardware does not receive beacons
>   *
>   * @vif: &struct ieee80211_vif pointer from the add_interface callback.
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index b80c386..59a1d38 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -1287,6 +1287,10 @@ int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
>  			     const u8 *ie, size_t ie_len,
>  			     enum ieee80211_band band, u32 rate_mask,
>  			     u8 channel);
> +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);
>  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);
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index a3a9421..dfc4a31 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -1108,6 +1108,30 @@ static void ieee80211_mgd_probe_ap(struct ieee80211_sub_if_data *sdata,
>  	mutex_unlock(&ifmgd->mtx);
>  }
>  
> +struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,
> +					  struct ieee80211_vif *vif)
> +{
> +	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
> +	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
> +	struct sk_buff *skb;
> +	const u8 *ssid;
> +
> +	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_STATION))
> +		return NULL;
> +
> +	ASSERT_MGD_MTX(ifmgd);
> +
> +	if (!ifmgd->associated)
> +		return NULL;
> +
> +	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);
> +
> +	return skb;
> +}
> +EXPORT_SYMBOL(ieee80211_ap_probereq_get);
> +
>  static void __ieee80211_connection_loss(struct ieee80211_sub_if_data *sdata)
>  {
>  	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index 0b6fc92..885713d 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -1011,9 +1011,10 @@ int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
>  	return pos - buffer;
>  }
>  
> -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)
> +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)
>  {
>  	struct ieee80211_local *local = sdata->local;
>  	struct sk_buff *skb;
> @@ -1027,7 +1028,7 @@ void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
>  	if (!buf) {
>  		printk(KERN_DEBUG "%s: failed to allocate temporary IE "
>  		       "buffer\n", sdata->name);
> -		return;
> +		return NULL;
>  	}
>  
>  	chan = ieee80211_frequency_to_channel(
> @@ -1050,8 +1051,20 @@ void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
>  	}
>  
>  	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
> -	ieee80211_tx_skb(sdata, skb);
>  	kfree(buf);
> +
> +	return skb;
> +}
> +
> +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)
> +{
> +	struct sk_buff *skb;
> +
> +	skb = ieee80211_build_probe_req(sdata, dst, ssid, ssid_len, ie, ie_len);
> +	if (skb)
> +		ieee80211_tx_skb(sdata, skb);
>  }
>  
>  u32 ieee80211_sta_get_rates(struct ieee80211_local *local,