P2P: Add preferred frequency list extension to GO Neg Req

When sending a GO Negotiation Request, advertise the preferred frequency
list in a new vendor specific IE. This can be used to extend the
standard P2P behavior where a single preferred channel can be advertised
by allowing a priority list of channels to be indicated.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

src/p2p/p2p_build.c

@@ -10,6 +10,7 @@
 
 #include "common.h"
 #include "common/ieee802_11_defs.h"
+#include "common/qca-vendor.h"
 #include "wps/wps_i.h"
 #include "p2p_i.h"
 
@@ -109,6 +110,44 @@ void p2p_buf_add_operating_channel(struct wpabuf *buf, const char *country,
 }
 
 
+void p2p_buf_add_pref_channel_list(struct wpabuf *buf,
+				   const u32 *preferred_freq_list,
+				   unsigned int size)
+{
+	unsigned int i, count = 0;
+	u8 op_class, op_channel;
+
+	if (!size)
+		return;
+
+	/*
+	 * First, determine the number of P2P supported channels in the
+	 * pref_freq_list returned from driver. This is needed for calculations
+	 * of the vendor IE size.
+	 */
+	for (i = 0; i < size; i++) {
+		if (p2p_freq_to_channel(preferred_freq_list[i], &op_class,
+					&op_channel) == 0)
+			count++;
+	}
+
+	wpabuf_put_u8(buf, WLAN_EID_VENDOR_SPECIFIC);
+	wpabuf_put_u8(buf, 4 + count * sizeof(u16));
+	wpabuf_put_be24(buf, OUI_QCA);
+	wpabuf_put_u8(buf, QCA_VENDOR_ELEM_P2P_PREF_CHAN_LIST);
+	for (i = 0; i < size; i++) {
+		if (p2p_freq_to_channel(preferred_freq_list[i], &op_class,
+					&op_channel) < 0) {
+			wpa_printf(MSG_DEBUG, "Unsupported frequency %u MHz",
+				   preferred_freq_list[i]);
+			continue;
+		}
+		wpabuf_put_u8(buf, op_class);
+		wpabuf_put_u8(buf, op_channel);
+	}
+}
+
+
 void p2p_buf_add_channel_list(struct wpabuf *buf, const char *country,
 			      struct p2p_channels *chan)
 {

src/p2p/p2p_go_neg.c

@@ -185,6 +185,9 @@ static struct wpabuf * p2p_build_go_neg_req(struct p2p_data *p2p,
 				      p2p->op_reg_class, p2p->op_channel);
 	p2p_buf_update_ie_hdr(buf, len);
 
+	p2p_buf_add_pref_channel_list(buf, p2p->pref_freq_list,
+				      p2p->num_pref_freq);
+
 	/* WPS IE with Device Password ID attribute */
 	pw_id = p2p_wps_method_pw_id(peer->wps_method);
 	if (peer->oob_pw_id)

src/p2p/p2p_i.h

@@ -769,6 +769,8 @@ void p2p_buf_add_persistent_group_info(struct wpabuf *buf, const u8 *dev_addr,
 				       const u8 *ssid, size_t ssid_len);
 int p2p_build_wps_ie(struct p2p_data *p2p, struct wpabuf *buf, int pw_id,
 		     int all_attr);
+void p2p_buf_add_pref_channel_list(struct wpabuf *buf,
+				   const u32 *preferred_freq_list, u32 size);
 
 /* p2p_sd.c */
 struct p2p_sd_query * p2p_pending_sd_req(struct p2p_data *p2p,