3 files changed, 67 insertions, 31 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 1a1d0d8203aa..784ab769b00b 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 a84ead49b1e6..6e5b57dccc50 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -2199,7 +2199,7 @@ 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 beacon_timestamp, rx_timestamp;
         DECLARE_MAC_BUF(mac);
         DECLARE_MAC_BUF(mac2);
 
@@ -2216,31 +2216,7 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
         if (baselen > len)
                 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 */
-        }
-
+        beacon_timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);
         ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);
 
         if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS && elems.supp_rates &&
@@ -2326,8 +2302,10 @@ 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;
         }
@@ -2424,13 +2402,67 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
                 bss->ht_ie_len = 0;
         }
 
-        bss->timestamp = timestamp;
+        bss->timestamp = beacon_timestamp;
         bss->last_update = jiffies;
         bss->rssi = rx_status->ssi;
         bss->signal = rx_status->signal;
         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
+                         *
+                         * since mactime is defined as the time the first data
+                         * symbol of the frame hits the PHY, and the timestamp
+                         * of the beacon is defined as "the time that the data
+                         * symbol containing the first bit of the timestamp is
+                         * transmitted to the PHY plus the transmitting STA’s
+                         * delays through its local PHY from the MAC-PHY
+                         * interface to its interface with the WM"
+                         * (802.11 11.1.2) - equals the time this bit arrives at
+                         * the receiver - we have to take into account the
+                         * offset between the two.
+                         * e.g: at 1 MBit that means mactime is 192 usec earlier
+                         * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
+                         */
+                        int rate = local->hw.wiphy->bands[rx_status->band]->
+                                        bitrates[rx_status->rate_idx].bitrate;
+                        rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
+                } else if (local && local->ops && local->ops->get_tsf)
+                        /* second best option: get current TSF */
+                        rx_timestamp = local->ops->get_tsf(local_to_hw(local));
+                else
+                        /* can't merge without knowing the TSF */
+                        rx_timestamp = -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)rx_timestamp,
+                       (unsigned long long)beacon_timestamp,
+                       (unsigned long long)(rx_timestamp - beacon_timestamp),
+                       jiffies);
+#endif /* CONFIG_MAC80211_IBSS_DEBUG */
+                if (beacon_timestamp > rx_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 472b19fc9143..279ee493520d 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1695,7 +1695,10 @@ 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;