Correct several issues with rate set negotiation:

o add IEEE80211_F_JOIN flag to ieee80211_fix_rate to indicate a station
  is joining a BSS; this is used to control whether or not we over-write
  the basic rate bit in the calculated rate set
o fix ieee80211_fix_rate to honor IEEE80211_F_DODEL when IEEE80211_F_DONEGO
  is not specified (e.g. when joining an ibss network)
o on sta join always delete unusable rates from the negotiated rate set,
  this was being done only ibss networks but is also needed for 11g bss
  with mixed stations
o on sta join delete unusable rates from the bss node's rate set, not the
  scan table entry's rate set
o when calculating a rate set for new neighbors in an ibss caculate a
  negotiated rate set so drivers are not presented with rates they should
  not use

Submitted by:	Sepherosa Ziehau (w/ modifications)
Obtained from:	DragonFly
MFC after:	1 month

sys/net80211/ieee80211_input.c

@@ -2471,6 +2471,7 @@ ieee80211_recv_mgmt(struct ieee80211com *ic, struct mbuf *m0,
 
 		IEEE80211_VERIFY_ELEMENT(rates, IEEE80211_RATE_MAXSIZE);
 		rate = ieee80211_setup_rates(ni, rates, xrates,
+				IEEE80211_F_JOIN |
 				IEEE80211_F_DOSORT | IEEE80211_F_DOFRATE |
 				IEEE80211_F_DONEGO | IEEE80211_F_DODEL);
 		if (rate & IEEE80211_RATE_BASIC) {

sys/net80211/ieee80211_node.c

@@ -517,7 +517,8 @@ ieee80211_match_bss(struct ieee80211com *ic, struct ieee80211_node *ni)
 		if (ni->ni_capinfo & IEEE80211_CAPINFO_PRIVACY)
 			fail |= 0x04;
 	}
-	rate = ieee80211_fix_rate(ni, IEEE80211_F_DONEGO | IEEE80211_F_DOFRATE);
+	rate = ieee80211_fix_rate(ni,
+	     IEEE80211_F_JOIN | IEEE80211_F_DONEGO | IEEE80211_F_DOFRATE);
 	if (rate & IEEE80211_RATE_BASIC)
 		fail |= 0x08;
 	if (ic->ic_des_esslen != 0 &&
@@ -802,11 +803,6 @@ ieee80211_sta_join(struct ieee80211com *ic, struct ieee80211_node *selbs)
 
 	if (ic->ic_opmode == IEEE80211_M_IBSS) {
 		struct ieee80211_node_table *nt;
-		/*
-		 * Delete unusable rates; we've already checked
-		 * that the negotiated rate set is acceptable.
-		 */
-		ieee80211_fix_rate(selbs, IEEE80211_F_DODEL);
 		/*
 		 * Fillin the neighbor table; it will already
 		 * exist if we are simply switching mastership.
@@ -828,6 +824,13 @@ ieee80211_sta_join(struct ieee80211com *ic, struct ieee80211_node *selbs)
 		copy_bss(selbs, obss);
 		ieee80211_free_node(obss);
 	}
+
+	/*
+	 * Delete unusable rates; we've already checked
+	 * that the negotiated rate set is acceptable.
+	 */
+	ieee80211_fix_rate(ic->ic_bss, IEEE80211_F_DODEL | IEEE80211_F_JOIN);
+
 	/*
 	 * Set the erp state (mostly the slot time) to deal with
 	 * the auto-select case; this should be redundant if the
@@ -1295,7 +1298,9 @@ ieee80211_init_neighbor(struct ieee80211_node *ni,
 		ieee80211_saveie(&ni->ni_wpa_ie, sp->wpa);
 
 	/* NB: must be after ni_chan is setup */
-	ieee80211_setup_rates(ni, sp->rates, sp->xrates, IEEE80211_F_DOSORT);
+	ieee80211_setup_rates(ni, sp->rates, sp->xrates,
+		IEEE80211_F_DOSORT | IEEE80211_F_DOFRATE |
+		IEEE80211_F_DONEGO | IEEE80211_F_DODEL);
 }
 
 /*

sys/net80211/ieee80211_proto.c

@@ -322,12 +322,23 @@ ieee80211_dump_pkt(const u_int8_t *buf, int len, int rate, int rssi)
 	}
 }
 
+static __inline int
+findrix(const struct ieee80211_rateset *rs, int r)
+{
+	int i;
+
+	for (i = 0; i < rs->rs_nrates; i++)
+		if ((rs->rs_rates[i] & IEEE80211_RATE_VAL) == r)
+			return i;
+	return -1;
+}
+
 int
 ieee80211_fix_rate(struct ieee80211_node *ni, int flags)
 {
 #define	RV(v)	((v) & IEEE80211_RATE_VAL)
 	struct ieee80211com *ic = ni->ni_ic;
-	int i, j, ignore, error;
+	int i, j, rix, error;
 	int okrate, badrate, fixedrate;
 	const struct ieee80211_rateset *srs;
 	struct ieee80211_rateset *nrs;
@@ -345,7 +356,6 @@ ieee80211_fix_rate(struct ieee80211_node *ni, int flags)
 	srs = ieee80211_get_suprates(ic, ni->ni_chan);
 	nrs = &ni->ni_rates;
 	for (i = 0; i < nrs->rs_nrates; ) {
-		ignore = 0;
 		if (flags & IEEE80211_F_DOSORT) {
 			/*
 			 * Sort rates.
@@ -367,51 +377,40 @@ ieee80211_fix_rate(struct ieee80211_node *ni, int flags)
 			if (r == RV(srs->rs_rates[ic->ic_fixed_rate]))
 				fixedrate = r;
 		}
+		/*
+		 * Check against supported rates.
+		 */
+		rix = findrix(srs, r);
 		if (flags & IEEE80211_F_DONEGO) {
-			/*
+			if (rix < 0) {
-			 * Check against supported rates.
-			 */
-			for (j = 0; j < srs->rs_nrates; j++) {
-				if (r == RV(srs->rs_rates[j])) {
-					/*
-					 * Overwrite with the supported rate
-					 * value so any basic rate bit is set.
-					 * This insures that response we send
-					 * to stations have the necessary basic
-					 * rate bit set.
-					 */
-					nrs->rs_rates[i] = srs->rs_rates[j];
-					break;
-				}
-			}
-			if (j == srs->rs_nrates) {
 				/*
 				 * A rate in the node's rate set is not
 				 * supported.  If this is a basic rate and we
-				 * are operating as an AP then this is an error.
+				 * are operating as a STA then this is an error.
 				 * Otherwise we just discard/ignore the rate.
-				 * Note that this is important for 11b stations
-				 * when they want to associate with an 11g AP.
 				 */
-				if (ic->ic_opmode == IEEE80211_M_HOSTAP &&
+				if ((flags & IEEE80211_F_JOIN) &&
 				    (nrs->rs_rates[i] & IEEE80211_RATE_BASIC))
 					error++;
-				ignore++;
+			} else if ((flags & IEEE80211_F_JOIN) == 0) {
+				/*
+				 * Overwrite with the supported rate
+				 * value so any basic rate bit is set.
+				 */
+				nrs->rs_rates[i] = srs->rs_rates[rix];
 			}
 		}
-		if (flags & IEEE80211_F_DODEL) {
+		if ((flags & IEEE80211_F_DODEL) && rix < 0) {
 			/*
 			 * Delete unacceptable rates.
 			 */
-			if (ignore) {
+			nrs->rs_nrates--;
-				nrs->rs_nrates--;
+			for (j = i; j < nrs->rs_nrates; j++)
-				for (j = i; j < nrs->rs_nrates; j++)
+				nrs->rs_rates[j] = nrs->rs_rates[j + 1];
-					nrs->rs_rates[j] = nrs->rs_rates[j + 1];
+			nrs->rs_rates[j] = 0;
-				nrs->rs_rates[j] = 0;
+			continue;
-				continue;
-			}
 		}
-		if (!ignore)
+		if (rix >= 0)
 			okrate = nrs->rs_rates[i];
 		i++;
 	}

sys/net80211/ieee80211_proto.h

@@ -180,6 +180,7 @@ const struct ieee80211_aclator *ieee80211_aclator_get(const char *name);
 #define	IEEE80211_F_DOFRATE	0x00000002	/* use fixed rate */
 #define	IEEE80211_F_DONEGO	0x00000004	/* calc negotiated rate */
 #define	IEEE80211_F_DODEL	0x00000008	/* delete ignore rate */
+#define	IEEE80211_F_JOIN	0x00000010	/* sta joining our bss */
 int	ieee80211_fix_rate(struct ieee80211_node *, int);
 
 /*