GAS server: Support comeback delay from the request handler

Allow GAS request handler function to request comeback delay before
providing the response.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

src/common/gas_server.c

@@ -1,6 +1,7 @@
 /*
  * Generic advertisement service (GAS) server
  * Copyright (c) 2017, Qualcomm Atheros, Inc.
+ * Copyright (c) 2020, The Linux Foundation
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -23,8 +24,9 @@ struct gas_server_handler {
 	struct dl_list list;
 	u8 adv_proto_id[MAX_ADV_PROTO_ID_LEN];
 	u8 adv_proto_id_len;
-	struct wpabuf * (*req_cb)(void *ctx, const u8 *sa,
+	struct wpabuf * (*req_cb)(void *ctx, void *resp_ctx, const u8 *sa,
-				  const u8 *query, size_t query_len);
+				  const u8 *query, size_t query_len,
+				  u16 *comeback_delay);
 	void (*status_cb)(void *ctx, struct wpabuf *resp, int ok);
 	void *ctx;
 	struct gas_server *gas;
@@ -39,6 +41,7 @@ struct gas_server_response {
 	u8 dst[ETH_ALEN];
 	u8 dialog_token;
 	struct gas_server_handler *handler;
+	u16 comeback_delay;
 };
 
 struct gas_server {
@@ -61,7 +64,8 @@ static void gas_server_response_timeout(void *eloop_ctx, void *user_ctx)
 		   response, MAC2STR(response->dst), response->dialog_token,
 		   response->freq, response->frag_id,
 		   (unsigned long) response->offset,
-		   (unsigned long) wpabuf_len(response->resp));
+		   (unsigned long) (response->resp ?
+				    wpabuf_len(response->resp) : 0));
 	response->handler->status_cb(response->handler->ctx,
 				     response->resp, 0);
 	response->resp = NULL;
@@ -83,30 +87,27 @@ static void gas_server_free_response(struct gas_server_response *response)
 
 static void
 gas_server_send_resp(struct gas_server *gas, struct gas_server_handler *handler,
+		     struct gas_server_response *response,
 		     const u8 *da, int freq, u8 dialog_token,
-		     struct wpabuf *query_resp)
+		     struct wpabuf *query_resp, u16 comeback_delay)
 {
 	size_t max_len = (freq > 56160) ? 928 : 1400;
 	size_t hdr_len = 24 + 2 + 5 + 3 + handler->adv_proto_id_len + 2;
 	size_t resp_frag_len;
 	struct wpabuf *resp;
-	u16 comeback_delay;
-	struct gas_server_response *response;
 
-	if (!query_resp)
+	if (comeback_delay == 0 && !query_resp)
 		return;
 
-	response = os_zalloc(sizeof(*response));
-	if (!response) {
-		wpabuf_free(query_resp);
-		return;
-	}
-	wpa_printf(MSG_DEBUG, "DPP: Allocated GAS response @%p", response);
 	response->freq = freq;
 	response->handler = handler;
 	os_memcpy(response->dst, da, ETH_ALEN);
 	response->dialog_token = dialog_token;
-	if (hdr_len + wpabuf_len(query_resp) > max_len) {
+	if (comeback_delay) {
+		/* Need more time to prepare the response */
+		resp_frag_len = 0;
+		response->comeback_delay = comeback_delay;
+	} else if (hdr_len + wpabuf_len(query_resp) > max_len) {
 		/* Need to use comeback to initiate fragmentation */
 		comeback_delay = 1;
 		resp_frag_len = 0;
@@ -135,10 +136,12 @@ gas_server_send_resp(struct gas_server *gas, struct gas_server_handler *handler,
 
 	/* Query Response Length */
 	wpabuf_put_le16(resp, resp_frag_len);
-	if (!comeback_delay)
+	if (!comeback_delay && query_resp)
 		wpabuf_put_buf(resp, query_resp);
 
-	if (comeback_delay) {
+	if (comeback_delay && !query_resp) {
+		wpa_printf(MSG_DEBUG, "GAS: No response available yet");
+	} else if (comeback_delay) {
 		wpa_printf(MSG_DEBUG,
 			   "GAS: Need to fragment query response");
 	} else {
@@ -165,6 +168,7 @@ gas_server_rx_initial_req(struct gas_server *gas, const u8 *da, const u8 *sa,
 	u16 query_req_len;
 	struct gas_server_handler *handler;
 	struct wpabuf *resp;
+	struct gas_server_response *response;
 
 	wpa_hexdump(MSG_MSGDUMP, "GAS: Received GAS Initial Request frame",
 		    data, len);
@@ -210,8 +214,15 @@ gas_server_rx_initial_req(struct gas_server *gas, const u8 *da, const u8 *sa,
 			    pos, end - pos);
 	}
 
+	response = os_zalloc(sizeof(*response));
+	if (!response)
+		return -1;
+
+	wpa_printf(MSG_DEBUG, "DPP: Allocated GAS response @%p", response);
 	dl_list_for_each(handler, &gas->handlers, struct gas_server_handler,
 			 list) {
+		u16 comeback_delay = 0;
+
 		if (adv_proto_len < 1 + handler->adv_proto_id_len ||
 		    os_memcmp(adv_proto + 1, handler->adv_proto_id,
 			      handler->adv_proto_id_len) != 0)
@@ -219,17 +230,22 @@ gas_server_rx_initial_req(struct gas_server *gas, const u8 *da, const u8 *sa,
 
 		wpa_printf(MSG_DEBUG,
 			   "GAS: Calling handler for the requested Advertisement Protocol ID");
-		resp = handler->req_cb(handler->ctx, sa, query_req,
+		resp = handler->req_cb(handler->ctx, response, sa, query_req,
-				       query_req_len);
+				       query_req_len, &comeback_delay);
 		wpa_hexdump_buf(MSG_MSGDUMP, "GAS: Response from the handler",
 				resp);
-		gas_server_send_resp(gas, handler, sa, freq, dialog_token,
+		if (comeback_delay)
-				     resp);
+			wpa_printf(MSG_DEBUG,
+				   "GAS: Handler requested comeback delay: %u TU",
+				   comeback_delay);
+		gas_server_send_resp(gas, handler, response, sa, freq,
+				     dialog_token, resp, comeback_delay);
 		return 0;
 	}
 
 	wpa_printf(MSG_DEBUG,
 		   "GAS: No registered handler for the requested Advertisement Protocol ID");
+	gas_server_free_response(response);
 	return -1;
 }
 
@@ -243,6 +259,31 @@ gas_server_handle_rx_comeback_req(struct gas_server_response *response)
 	size_t hdr_len = 24 + 2 + 6 + 3 + handler->adv_proto_id_len + 2;
 	size_t remaining, resp_frag_len;
 	struct wpabuf *resp;
+	unsigned int wait_time = 0;
+
+	if (!response->resp) {
+		resp = gas_build_comeback_resp(response->dialog_token,
+					       WLAN_STATUS_SUCCESS, 0, 0,
+					       response->comeback_delay,
+					       handler->adv_proto_id_len);
+		if (!resp) {
+			dl_list_del(&response->list);
+			gas_server_free_response(response);
+			return;
+		}
+
+		/* Advertisement Protocol element */
+		wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
+		wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
+		wpabuf_put_u8(resp, 0x7f);
+		/* Advertisement Protocol ID */
+		wpabuf_put_data(resp, handler->adv_proto_id,
+				handler->adv_proto_id_len);
+
+		/* Query Response Length */
+		wpabuf_put_le16(resp, 0);
+		goto send_resp;
+	}
 
 	remaining = wpabuf_len(response->resp) - response->offset;
 	if (hdr_len + remaining > max_len)
@@ -279,8 +320,11 @@ gas_server_handle_rx_comeback_req(struct gas_server_response *response)
 
 	response->offset += resp_frag_len;
 
-	gas->tx(gas->ctx, response->freq, response->dst, resp,
+	if (remaining > resp_frag_len)
-		remaining > resp_frag_len ? 2000 : 0);
+		wait_time = 2000;
+
+send_resp:
+	gas->tx(gas->ctx, response->freq, response->dst, resp, wait_time);
 	wpabuf_free(resp);
 }
 
@@ -359,12 +403,19 @@ int gas_server_rx(struct gas_server *gas, const u8 *da, const u8 *sa,
 static void gas_server_handle_tx_status(struct gas_server_response *response,
 					int ack)
 {
-	if (ack && response->offset < wpabuf_len(response->resp)) {
+	if (ack && response->resp &&
+	    response->offset < wpabuf_len(response->resp)) {
 		wpa_printf(MSG_DEBUG,
 			   "GAS: More fragments remaining - keep pending entry");
 		return;
 	}
 
+	if (ack && !response->resp && response->comeback_delay) {
+		wpa_printf(MSG_DEBUG,
+			   "GAS: Waiting for response - keep pending entry");
+		return;
+	}
+
 	if (!ack)
 		wpa_printf(MSG_DEBUG,
 			   "GAS: No ACK received - drop pending entry");
@@ -415,6 +466,27 @@ void gas_server_tx_status(struct gas_server *gas, const u8 *dst, const u8 *data,
 }
 
 
+int gas_server_set_resp(struct gas_server *gas, void *resp_ctx,
+			struct wpabuf *resp)
+{
+	struct gas_server_response *tmp, *response = NULL;
+
+	dl_list_for_each(tmp, &gas->responses, struct gas_server_response,
+			 list) {
+		if (tmp == resp_ctx) {
+			response = tmp;
+			break;
+		}
+	}
+
+	if (!response || response->resp)
+		return -1;
+
+	response->resp = resp;
+	return 0;
+}
+
+
 struct gas_server * gas_server_init(void *ctx,
 				    void (*tx)(void *ctx, int freq,
 					       const u8 *da,
@@ -461,8 +533,9 @@ void gas_server_deinit(struct gas_server *gas)
 int gas_server_register(struct gas_server *gas,
 			const u8 *adv_proto_id, u8 adv_proto_id_len,
 			struct wpabuf *
-			(*req_cb)(void *ctx, const u8 *sa,
+			(*req_cb)(void *ctx, void *resp_ctx, const u8 *sa,
-				  const u8 *query, size_t query_len),
+				  const u8 *query, size_t query_len,
+				  u16 *comeback_delay),
 			void (*status_cb)(void *ctx, struct wpabuf *resp,
 					  int ok),
 			void *ctx)

src/common/gas_server.h

@@ -1,6 +1,7 @@
 /*
  * Generic advertisement service (GAS) server
  * Copyright (c) 2017, Qualcomm Atheros, Inc.
+ * Copyright (c) 2020, The Linux Foundation
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -22,8 +23,9 @@ void gas_server_deinit(struct gas_server *gas);
 int gas_server_register(struct gas_server *gas,
 			const u8 *adv_proto_id, u8 adv_proto_id_len,
 			struct wpabuf *
-			(*req_cb)(void *ctx, const u8 *sa,
+			(*req_cb)(void *ctx, void *resp_ctx, const u8 *sa,
-				  const u8 *query, size_t query_len),
+				  const u8 *query, size_t query_len,
+				  u16 *comeback_delay),
 			void (*status_cb)(void *ctx, struct wpabuf *resp,
 					  int ok),
 			void *ctx);
@@ -32,6 +34,8 @@ int gas_server_rx(struct gas_server *gas, const u8 *da, const u8 *sa,
 		  int freq);
 void gas_server_tx_status(struct gas_server *gas, const u8 *dst, const u8 *data,
 			  size_t data_len, int ack);
+int gas_server_set_resp(struct gas_server *gas, void *resp_ctx,
+			struct wpabuf *resp);
 
 #else /* CONFIG_GAS_SERVER */
 

wpa_supplicant/dpp_supplicant.c

@@ -2647,8 +2647,8 @@ void wpas_dpp_rx_action(struct wpa_supplicant *wpa_s, const u8 *src,
 
 
 static struct wpabuf *
-wpas_dpp_gas_req_handler(void *ctx, const u8 *sa, const u8 *query,
+wpas_dpp_gas_req_handler(void *ctx, void *resp_ctx, const u8 *sa,
-			 size_t query_len)
+			 const u8 *query, size_t query_len, u16 *comeback_delay)
 {
 	struct wpa_supplicant *wpa_s = ctx;
 	struct dpp_authentication *auth = wpa_s->dpp_auth;