Fix a problem with associating to wifi networks with a hidden SSID.

If an AP is configured to hide its SSID it sends a non-zero length SSID
which contains only zeroes. The AP sends its actual SSID only in probe
responses after a client includes this SSID in a probe request.
If we happened to receive a beacon before the probe response we stored a
non-zero-length SSID of zeroes and never updated the SSID when the probe
response arrived. The client was then unable to find the AP.

test & ok jung@

diff --git a/sys/net80211/ieee80211_input.c b/sys/net80211/ieee80211_input.c
index 8fd5a9c..65b2e22 100644 (file)
--- a/sys/net80211/ieee80211_input.c
+++ b/sys/net80211/ieee80211_input.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ieee80211_input.c,v 1.191 2017/04/11 14:43:49 dhill Exp $     */
+/*     $OpenBSD: ieee80211_input.c,v 1.192 2017/05/02 11:03:48 stsp Exp $      */
 
 /*-
  * Copyright (c) 2001 Atsushi Onoe
@@ -1549,9 +1549,24 @@ ieee80211_recv_probe_resp(struct ieee80211com *ic, struct mbuf *m,
         * for this APs does not exist or if the new node is the
         * potential better one.
         */
-       if ((ni = ieee80211_find_node_for_beacon(ic, wh->i_addr2,
-           &ic->ic_channels[chan], ssid, rxi->rxi_rssi)) != NULL)
+       ni = ieee80211_find_node_for_beacon(ic, wh->i_addr2,
+           &ic->ic_channels[chan], ssid, rxi->rxi_rssi);
+       if (ni != NULL) {
+               /*
+                * If we are doing a directed scan for an AP with a hidden SSID
+                * we must collect the SSID from a probe response to override
+                * a non-zero-length SSID filled with zeroes that we may have
+                * received earlier in a beacon.
+                */
+               if (isprobe && ssid[1] != 0 && ni->ni_essid[0] == '\0') {
+                       ni->ni_esslen = ssid[1];
+                       memset(ni->ni_essid, 0, sizeof(ni->ni_essid));
+                       /* we know that ssid[1] <= IEEE80211_NWID_LEN */
+                       memcpy(ni->ni_essid, &ssid[2], ssid[1]);
+               }
+
                return;
+       }
 
 #ifdef IEEE80211_DEBUG
        if (ieee80211_debug > 1 &&
@@ -1711,7 +1726,7 @@ ieee80211_recv_probe_resp(struct ieee80211com *ic, struct mbuf *m,
                }
        }
 
-       if (ssid[1] != 0 && ni->ni_esslen == 0) {
+       if (ssid[1] != 0 && ni->ni_essid[0] == '\0') {
                ni->ni_esslen = ssid[1];
                memset(ni->ni_essid, 0, sizeof(ni->ni_essid));
                /* we know that ssid[1] <= IEEE80211_NWID_LEN */