> enable IBSS cell merging. if an IBSS beacon with the same ESSID and a TSF
> higher than the local TSF (mactime) is received, we have to join its BSSID.
Can you back that up with standard references? I see no such requirement
in the standard text. I can see that under some circumstances this may
be desirable, but maybe not.
In fact, this seems to *break* standard behaviour, as per 11.1.3.1:
(emphasis mine)
When a STA starts a BSS, that STA shall determine the BSSID of
the BSS. If the BSSType indicates an infrastructure BSS, then
the STA shall start an infrastructure BSS and the BSSID shall be
equal to the STA’s dot11StationID. ***The value of the BSSID
shall remain unchanged***, even if the value of dot11StationID
is changed after the completion of the MLME-START.request. If
the BSSType indicates an IBSS, the STA shall start an IBSS, and
the BSSID shall be an individual locally administered IEEE MAC
address as defined in 5.2 of IEEE Std 802-1990. The remaining 46
bits of that MAC address shall be a number selected in a manner
that minimizes the probability of STAs generating the same
number, even when those STAs are subjected to the same initial
conditions.
Remember that BSSIDs, *not* SSIDs are used to identify BSSes uniquely.
Of course you could argue that "merging" is simply tearing down the own
and then joining the other IBSS.
Comments on the code now.
> --- a/net/mac80211/ieee80211_sta.c
> +++ b/net/mac80211/ieee80211_sta.c
> @@ -80,6 +80,9 @@ static void ieee80211_rx_bss_put(struct net_device *dev,
> struct ieee80211_sta_bss *bss);
> static int ieee80211_sta_find_ibss(struct net_device *dev,
> struct ieee80211_if_sta *ifsta);
> +static int ieee80211_sta_join_ibss(struct net_device *dev,
> + struct ieee80211_if_sta *ifsta,
> + struct ieee80211_sta_bss *bss);
No way, order the code properly, this mess needs to be cleaned up not
added to.
> - if (bss->probe_resp && beacon) {
> + if (sdata->vif.type != IEEE80211_IF_TYPE_IBSS &&
> + bss->probe_resp && beacon) {
> /* Do not allow beacon to override data from Probe Response. */
Ahem. Comment update required.
> + /* check if we need to merge IBSS */
Could use a plural, but whatever.
> + 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 &&
> + memcmp(elems.ssid, sdata->u.sta.ssid, sdata->u.sta.ssid_len) == 0) {
I think that needs a check "&& ssid_len" or something. Someone's bound
to try making an IBSS with a hidden SSID and we really don't want that
to work.
> +#ifdef CONFIG_MAC80211_IBSS_DEBUG
> + static unsigned long last_tsf_debug;
> +#endif
Let's just get rid of that, it's not usable with multiple devices.
> + if (rx_status->flag & RX_FLAG_TSFT)
> + mactime = rx_status->mactime;
> + else {
> + mactime = -1LLU;
> + printk(KERN_WARNING "%s: IBSS mode needs mactime for "
> + "beacons\n", dev->name);
Very bad, you'll be flooded by this when others send beacons. Also, I
doubt its truthfulness.
> + printk(KERN_DEBUG "%s: beacon TSF higher than local TSF"
> + " -> IBSS merge with BSSID %s\n",
> + dev->name, print_mac(mac, mgmt->bssid));
No way. At the very least you need to ratelimit this.
johannes
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