hostapd: Add an option to notify management frames on ctrl_iface

In some contexts (e.g., Multi-AP) it can be useful to have access to
some of the management frames in upper layers (e.g., to be able to
process the content of association requests externally).

Add 'notify_mgmt_frames'. When enabled, it will notify the ctrl_iface
when a management frame arrives using the AP-MGMT-FRAME-RECEIVED event
message.

Note that to avoid completely flooding the ctrl_iface, not all
management frames are included (e.g., Beacon and Probe Request frames
are excluded).

Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>

hostapd/config_file.c

@@ -4368,6 +4368,8 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 		bss->multicast_to_unicast = atoi(pos);
 	} else if (os_strcmp(buf, "broadcast_deauth") == 0) {
 		bss->broadcast_deauth = atoi(pos);
+	} else if (os_strcmp(buf, "notify_mgmt_frames") == 0) {
+		bss->notify_mgmt_frames = atoi(pos);
 #ifdef CONFIG_DPP
 	} else if (os_strcmp(buf, "dpp_name") == 0) {
 		os_free(bss->dpp_name);

hostapd/hostapd.conf

@@ -571,6 +571,10 @@ wmm_ac_vo_acm=0
 # Default: 1 (enabled)
 #broadcast_deauth=1
 
+# Get notifications for received Management frames on control interface
+# Default: 0 (disabled)
+#notify_mgmt_frames=0
+
 ##### IEEE 802.11n related configuration ######################################
 
 # ieee80211n: Whether IEEE 802.11n (HT) is enabled

src/ap/ap_config.h

@@ -736,6 +736,8 @@ struct hostapd_bss_config {
 
 	int broadcast_deauth;
 
+	int notify_mgmt_frames;
+
 #ifdef CONFIG_DPP
 	char *dpp_name;
 	char *dpp_mud_url;

src/ap/ieee802_11.c

@@ -6023,6 +6023,31 @@ static int handle_action(struct hostapd_data *hapd,
 }
 
 
+/**
+ * notify_mgmt_frame - Notify of Management frames on the control interface
+ * @hapd: hostapd BSS data structure (the BSS to which the Management frame was
+ * sent to)
+ * @buf: Management frame data (starting from the IEEE 802.11 header)
+ * @len: Length of frame data in octets
+ *
+ * Notify the control interface of any received Management frame.
+ */
+static void notify_mgmt_frame(struct hostapd_data *hapd, const u8 *buf,
+			      size_t len)
+{
+
+	int hex_len = len * 2 + 1;
+	char *hex = os_malloc(hex_len);
+
+	if (hex) {
+		wpa_snprintf_hex(hex, hex_len, buf, len);
+		wpa_msg_ctrl(hapd->msg_ctx, MSG_INFO,
+			     AP_MGMT_FRAME_RECEIVED "buf=%s", hex);
+		os_free(hex);
+	}
+}
+
+
 /**
  * ieee802_11_mgmt - process incoming IEEE 802.11 management frames
  * @hapd: hostapd BSS data structure (the BSS to which the management frame was
@@ -6113,6 +6138,9 @@ int ieee802_11_mgmt(struct hostapd_data *hapd, const u8 *buf, size_t len,
 	if (hapd->iconf->track_sta_max_num)
 		sta_track_add(hapd->iface, mgmt->sa, ssi_signal);
 
+	if (hapd->conf->notify_mgmt_frames)
+		notify_mgmt_frame(hapd, buf, len);
+
 	switch (stype) {
 	case WLAN_FC_STYPE_AUTH:
 		wpa_printf(MSG_DEBUG, "mgmt::auth");

src/common/wpa_ctrl.h

@@ -404,6 +404,9 @@ extern "C" {
  * frame=<saqueryreq/saqueryresp> error=<error string> */
 #define OCV_FAILURE "OCV-FAILURE "
 
+/* Event triggered for received management frame */
+#define AP_MGMT_FRAME_RECEIVED "AP-MGMT-FRAME-RECEIVED "
+
 #ifndef BIT
 #define BIT(x) (1U << (x))
 #endif