Some APs will not negotiate 11n (aka HT) if the vendor-specific WME
(Wireless Multimedia Extensions) info element is missing in probe
and association requests. WME info essentially tells the other end
that we're QoS capable, which is a requirement for 11n (e.g. A-MPDUs
are sent in QoS data frames).
The 802.11-2012 standard defines other ways of indicating QoS support
which we already use. WME is not part of this standard but I'm adding
it for interoperability. FreeBSD and Linux send a WME info element, too.
Since this is an ugly vendor-specific element I decided to use magic
numbers instead of IEEE80211_ defines. I have no document explaining
what these numbers really mean, and Linux and FreeBSD use different
terminology. I put the names FreeBSD uses in comments.
Also, fix bugs where the wrong flag was checked to determine whether
11n-related elements should be included in management frames.
If 11n mode is enabled (F_HTON flag) we can always include 11n related
elements in management frames we send out, regardless of whether the
other STAs or APs support 11n.
The NODE_HT flag is only set once HT has been negotiated with a peer,
i.e. after exchanging assoc request and response with the AP.
Checking this flag earlier, e.g. in ieee80211_get_assoc_resp(), is wrong.
Index: net80211/ieee80211_output.c
===================================================================
RCS file: /cvs/src/sys/net80211/ieee80211_output.c,v
retrieving revision 1.101
diff -u -p -r1.101 ieee80211_output.c
--- net80211/ieee80211_output.c 24 Nov 2015 12:32:53 -0000 1.101
+++ net80211/ieee80211_output.c 12 Dec 2015 10:12:58 -0000
@@ -94,6 +94,7 @@ struct mbuf *ieee80211_get_addba_resp(st
struct ieee80211_node *, u_int8_t, u_int8_t, u_int16_t);
struct mbuf *ieee80211_get_delba(struct ieee80211com *,
struct ieee80211_node *, u_int8_t, u_int8_t, u_int16_t);
+uint8_t *ieee80211_add_wme_info(uint8_t *, struct ieee80211com *);
#endif
struct mbuf *ieee80211_get_sa_query(struct ieee80211com *,
struct ieee80211_node *, u_int8_t);
@@ -831,6 +832,26 @@ ieee80211_add_qos_capability(u_int8_t *f
return frm;
}
+#ifndef IEEE80211_NO_HT
+/*
+ * Add a Wifi-Alliance WME (aka WMM) info element to a frame.
+ * WME is a requirement for Wifi-Alliance compliance and some
+ * 11n APs will not negotiate HT if this element is missing.
+ */
+uint8_t *
+ieee80211_add_wme_info(uint8_t *frm, struct ieee80211com *ic)
+{
+ *frm++ = IEEE80211_ELEMID_VENDOR;
+ *frm++ = 7;
+ memcpy(frm, MICROSOFT_OUI, 3); frm += 3;
+ *frm++ = 2; /* OUI type */
+ *frm++ = 0; /* OUI subtype */
+ *frm++ = 1; /* version */
+ *frm++ = 0; /* info */
+
+ return frm;
+}
+#endif
/*
* Add an RSN element to a frame (see 802.11-2012 8.4.2.27)
*/
@@ -1097,7 +1118,7 @@ ieee80211_get_probe_req(struct ieee80211
2 + min(rs->rs_nrates, IEEE80211_RATE_SIZE) +
((rs->rs_nrates > IEEE80211_RATE_SIZE) ?
2 + rs->rs_nrates - IEEE80211_RATE_SIZE : 0) +
- ((ni->ni_flags & IEEE80211_NODE_HT) ? 28 : 0));
+ ((ic->ic_flags & IEEE80211_F_HTON) ? 28 + 9 : 0));
if (m == NULL)
return NULL;
@@ -1107,8 +1128,10 @@ ieee80211_get_probe_req(struct ieee80211
if (rs->rs_nrates > IEEE80211_RATE_SIZE)
frm = ieee80211_add_xrates(frm, rs);
#ifndef IEEE80211_NO_HT
- if (ni->ni_flags & IEEE80211_NODE_HT)
+ if (ic->ic_flags & IEEE80211_F_HTON) {
frm = ieee80211_add_htcaps(frm, ic);
+ frm = ieee80211_add_wme_info(frm, ic);
+ }
#endif
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
@@ -1278,7 +1301,7 @@ ieee80211_get_assoc_req(struct ieee80211
(((ic->ic_flags & IEEE80211_F_RSNON) &&
(ni->ni_rsnprotos & IEEE80211_PROTO_WPA)) ?
2 + IEEE80211_WPAIE_MAXLEN : 0) +
- ((ni->ni_flags & IEEE80211_NODE_HT) ? 28 : 0));
+ ((ic->ic_flags & IEEE80211_F_HTON) ? 28 + 9 : 0));
if (m == NULL)
return NULL;
@@ -1310,8 +1333,10 @@ ieee80211_get_assoc_req(struct ieee80211
(ni->ni_rsnprotos & IEEE80211_PROTO_WPA))
frm = ieee80211_add_wpa(frm, ic, ni);
#ifndef IEEE80211_NO_HT
- if (ni->ni_flags & IEEE80211_NODE_HT)
+ if (ic->ic_flags & IEEE80211_F_HTON) {
frm = ieee80211_add_htcaps(frm, ic);
+ frm = ieee80211_add_wme_info(frm, ic);
+ }
#endif
m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
@@ -1347,7 +1372,7 @@ ieee80211_get_assoc_resp(struct ieee8021
2 + rs->rs_nrates - IEEE80211_RATE_SIZE : 0) +
((ni->ni_flags & IEEE80211_NODE_QOS) ? 2 + 18 : 0) +
((status == IEEE80211_STATUS_TRY_AGAIN_LATER) ? 2 + 7 : 0) +
- ((ni->ni_flags & IEEE80211_NODE_HT) ? 28 + 24 : 0));
+ ((ic->ic_flags & IEEE80211_F_HTON) ? 28 + 24 : 0));
if (m == NULL)
return NULL;
@@ -1370,7 +1395,7 @@ ieee80211_get_assoc_resp(struct ieee8021
frm = ieee80211_add_tie(frm, 3, 1000 /* XXX */);
}
#ifndef IEEE80211_NO_HT
- if (ni->ni_flags & IEEE80211_NODE_HT) {
+ if (ic->ic_flags & IEEE80211_F_HTON) {
frm = ieee80211_add_htcaps(frm, ic);
frm = ieee80211_add_htop(frm, ic);
}
