sdp_client: add sdp_client_register_query_callback() allows to register query request instead of polling sdp_client_ready()

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - `btstack_run_loop_base`: added `btstack_run_loop_base_dump_timer`
 - GAP: request role change for classic connection via `gap_request_role`
 - GAP: LE Whitelist API with 'gap_le_whitelist_x' with x = add, remove, clear and new `gap_connect_with_whitelist`
+- SDP Client: add sdp_client_register_query_callback() allows to register query request instead of polling sdp_client_ready()
 
 ### Changed
 - GAP: treat AES-CCM encrypted connection as mutually authenticated (BIAS)

src/classic/sdp_client.c

@@ -116,6 +116,10 @@ static uint8_t   continuationState[16];
 static uint8_t   continuationStateLen;
 static sdp_client_state_t sdp_client_state = INIT;
 static SDP_PDU_ID_t PDU_ID = SDP_Invalid;
+
+// Query registration
+static btstack_linked_list_t sdp_client_query_requests;
+
 #ifdef ENABLE_SDP_EXTRA_QUERIES
 static uint32_t serviceRecordHandle;
 static uint32_t record_handle;
@@ -307,12 +311,30 @@ void sdp_parser_handle_service_search(uint8_t * data, uint16_t total_count, uint
 }
 #endif
 
+static void sdp_client_notify_callbacks(void){
+    if (!sdp_client_ready) {
+        return;
+    }
+    btstack_context_callback_registration_t * callback = btstack_linked_list_pop(&sdp_client_query_requests);
+    if (callback == NULL) {
+        return;
+    }
+    (*callback->callback)(callback->callback);
+}
+
 void sdp_parser_handle_done(uint8_t status){
+    // reset state
+    sdp_client_state = INIT;
+
+    // emit query complete event
     uint8_t event[3];
     event[0] = SDP_EVENT_QUERY_COMPLETE;
     event[1] = 1;
     event[2] = status;
     (*sdp_parser_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event)); 
+
+    // trigger next query if pending
+    sdp_client_notify_callbacks();
 }
 
 // SDP Client
@@ -447,7 +469,6 @@ void sdp_client_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *p
             // data: event (8), len(8), status (8), address(48), handle (16), psm (16), local_cid(16), remote_cid (16), local_mtu(16), remote_mtu(16) 
             if (packet[2]) {
                 log_info("SDP Client Connection failed, status 0x%02x.", packet[2]);
-                sdp_client_state = INIT;
                 sdp_parser_handle_done(packet[2]);
                 break;
             }
@@ -472,7 +493,6 @@ void sdp_client_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *p
             }
             log_info("SDP Client disconnected.");
             uint8_t status = (sdp_client_state == QUERY_COMPLETE) ? 0 : SDP_QUERY_INCOMPLETE;
-            sdp_client_state = INIT;
             sdp_parser_handle_done(status);
             break;
         }
@@ -686,6 +706,13 @@ int sdp_client_ready(void){
     return sdp_client_state == INIT;
 }
 
+uint8_t sdp_client_register_query_callback(btstack_context_callback_registration_t * callback_registration){
+    bool added = btstack_linked_list_add_tail(&sdp_client_query_requests, (btstack_linked_item_t*) callback_registration);
+    if (!added) return ERROR_CODE_COMMAND_DISALLOWED;
+    sdp_client_notify_callbacks();
+    return ERROR_CODE_SUCCESS;
+}
+
 uint8_t sdp_client_query(btstack_packet_handler_t callback, bd_addr_t remote, const uint8_t * des_service_search_pattern, const uint8_t * des_attribute_id_list){
     if (!sdp_client_ready()) return SDP_QUERY_BUSY;
 

src/classic/sdp_client.h

@@ -64,10 +64,18 @@ int  de_state_size(uint8_t eventByte, de_state_t *de_state);
 
 /** 
  * @brief Checks if the SDP Client is ready
+ * @deprecated Please use sdp_client_register_query_callback instead
  * @return 1 when no query is active
  */
 int sdp_client_ready(void);
 
+/**
+ * @brief Requests a callback, when the SDP Client is ready and can be used
+ * @note The callback might happens before sdp_client_register_query_callback has returned
+ * @param callback_registration
+ */
+uint8_t sdp_client_register_query_callback(btstack_context_callback_registration_t * callback_registration);
+
 /** 
  * @brief Queries the SDP service of the remote device given a service search pattern and a list of attribute IDs. 
  * The remote data is handled by the SDP parser. The SDP parser delivers attribute values and done event via the callback.