uups, sorry stg mail (well, i...) confused the subject lines
bruno
On Wednesday 06 February 2008 11:46:40 Bruno Randolf wrote:
> mac80211: enable IBSS merging
>
> enable IBSS cell merging. if an IBSS beacon with the same channel, same
> ESSID and a TSF higher than the local TSF (mactime) is received, we have to
> join its BSSID. while this might not be immediately apparent from reading
> the 802.11 standard it is compliant and necessary to make IBSS mode
> functional in many cases. most drivers have a similar behaviour.
>
> * move the relevant code section (previously only containing debug code)
> down to the end of the function, so we can reuse the bss structure.
>
> * we have to compare the mactime (TSF at the time of packet receive) rather
> than the current TSF. since some drivers are not able to give a reliable
> mactime we fall back to use the current TSF, which will be enough to catch
> most (but not all) cases where an IBSS merge is necessary.
>
> * in IBSS mode we want to allow beacons to override probe response info so
> we can correctly do merges.
>
> * we don't only configure beacons based on scan results, so change that
> message.
>
> * to enable this we have to let all beacons thru in IBSS mode, even if they
> have a different BSSID.
>
> Signed-off-by: Bruno Randolf <bruno@xxxxxxxxxxxxx>
> ---
>
> include/net/mac80211.h | 3 +-
> net/mac80211/ieee80211_sta.c | 70
> ++++++++++++++++++++++++++---------------- net/mac80211/rx.c |
> 5 ++-
> 3 files changed, 49 insertions(+), 29 deletions(-)
>
>
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 460da54..4ae3a12 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -276,7 +276,8 @@ struct ieee80211_tx_control {
> * @RX_FLAG_FAILED_PLCP_CRC: Set this flag if the PCLP check failed on
> * the frame.
> * @RX_FLAG_TSFT: The timestamp passed in the RX status (@mactime field)
> - * is valid.
> + * is valid. This is useful in monitor mode and necessary for beacon
> frames + * to enable IBSS merging.
> */
> enum mac80211_rx_flags {
> RX_FLAG_MMIC_ERROR = 1<<0,
> diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
> index 08f89fa..4df18ae 100644
> --- a/net/mac80211/ieee80211_sta.c
> +++ b/net/mac80211/ieee80211_sta.c
> @@ -2202,7 +2202,7 @@ static void ieee80211_rx_bss_info(struct net_device
> *dev, struct ieee80211_sta_bss *bss;
> struct sta_info *sta;
> struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> - u64 timestamp;
> + u64 timestamp, mactime;
> DECLARE_MAC_BUF(mac);
> DECLARE_MAC_BUF(mac2);
>
> @@ -2220,30 +2220,6 @@ static void ieee80211_rx_bss_info(struct net_device
> *dev, return;
>
> timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);
> -
> - if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && beacon &&
> - memcmp(mgmt->bssid, sdata->u.sta.bssid, ETH_ALEN) == 0) {
> -#ifdef CONFIG_MAC80211_IBSS_DEBUG
> - static unsigned long last_tsf_debug = 0;
> - u64 tsf;
> - if (local->ops->get_tsf)
> - tsf = local->ops->get_tsf(local_to_hw(local));
> - else
> - tsf = -1LLU;
> - if (time_after(jiffies, last_tsf_debug + 5 * HZ)) {
> - printk(KERN_DEBUG "RX beacon SA=%s BSSID="
> - "%s TSF=0x%llx BCN=0x%llx diff=%lld "
> - "@%lu\n",
> - print_mac(mac, mgmt->sa), print_mac(mac2, mgmt->bssid),
> - (unsigned long long)tsf,
> - (unsigned long long)timestamp,
> - (unsigned long long)(tsf - timestamp),
> - jiffies);
> - last_tsf_debug = jiffies;
> - }
> -#endif /* CONFIG_MAC80211_IBSS_DEBUG */
> - }
> -
> ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);
>
> if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && elems.supp_rates &&
> @@ -2329,8 +2305,10 @@ static void ieee80211_rx_bss_info(struct net_device
> *dev,
>
> bss->band = rx_status->band;
>
> - if (bss->probe_resp && beacon) {
> - /* Do not allow beacon to override data from Probe Response. */
> + if (sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
> + bss->probe_resp && beacon) {
> + /* STA mode:
> + * Do not allow beacon to override data from Probe Response. */
> ieee80211_rx_bss_put(dev, bss);
> return;
> }
> @@ -2434,6 +2412,44 @@ static void ieee80211_rx_bss_info(struct net_device
> *dev, bss->noise = rx_status->noise;
> if (!beacon)
> bss->probe_resp++;
> +
> + /* check if we need to merge IBSS */
> + if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && beacon &&
> + !local->sta_sw_scanning && !local->sta_hw_scanning &&
> + mgmt->u.beacon.capab_info & WLAN_CAPABILITY_IBSS &&
> + bss->freq == local->oper_channel->center_freq &&
> + elems.ssid_len == sdata->u.sta.ssid_len &&
> + memcmp(elems.ssid, sdata->u.sta.ssid, sdata->u.sta.ssid_len) == 0) {
> + if (rx_status->flag & RX_FLAG_TSFT)
> + /* in order for correct IBSS merging we need mactime */
> + mactime = rx_status->mactime;
> + else if (local && local->ops && local->ops->get_tsf)
> + /* second best option: get current TSF */
> + mactime = local->ops->get_tsf(local_to_hw(local));
> + else
> + /* can't merge without knowing the TSF */
> + mactime = -1LLU;
> +#ifdef CONFIG_MAC80211_IBSS_DEBUG
> + printk(KERN_DEBUG "RX beacon SA=%s BSSID="
> + "%s TSF=0x%llx BCN=0x%llx diff=%lld @%lu\n",
> + print_mac(mac, mgmt->sa),
> + print_mac(mac2, mgmt->bssid),
> + (unsigned long long)mactime,
> + (unsigned long long)timestamp,
> + (unsigned long long)(mactime - timestamp),
> + jiffies);
> +#endif /* CONFIG_MAC80211_IBSS_DEBUG */
> + if (mactime <= timestamp) {
> + if (CONFIG_MAC80211_IBSS_DEBUG || net_ratelimit())
> + printk(KERN_DEBUG "%s: beacon TSF higher than "
> + "local TSF - IBSS merge with BSSID %s\n",
> + dev->name, print_mac(mac, mgmt->bssid));
> + ieee80211_sta_join_ibss(dev, &sdata->u.sta, bss);
> + ieee80211_ibss_add_sta(dev, NULL,
> + mgmt->bssid, mgmt->sa);
> + }
> + }
> +
> ieee80211_rx_bss_put(dev, bss);
> }
>
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index beda1bf..ed7cf37 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -1612,7 +1612,10 @@ static int prepare_for_handlers(struct
> ieee80211_sub_if_data *sdata, case IEEE80211_IF_TYPE_IBSS:
> if (!bssid)
> return 0;
> - if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
> + if ((rx->fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT &&
> + (rx->fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_BEACON)
> + return 1;
> + else if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
> if (!(rx->flags & IEEE80211_TXRXD_RXIN_SCAN))
> return 0;
> rx->flags &= ~IEEE80211_TXRXD_RXRA_MATCH;
>
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