l2cap: track minimal security level

src/gap.h

@@ -278,6 +278,13 @@ void gap_set_secure_connections_only_mode(bool enable);
  */
 bool gap_get_secure_connections_only_mode(void);
 
+/**
+ * @brief Set minimal security level for registered services
+ * @param security_level
+ * @note Called by L2CAP based on registered services
+ */
+void gap_set_minimal_service_security_level(gap_security_level_t security_level);
+
 /**
  * @brief Register filter for rejecting classic connections. Callback will return 1 accept connection, 0 on reject.
  */

src/hci.c

@@ -3509,6 +3509,10 @@ gap_security_level_t gap_get_security_level(void){
     return hci_stack->gap_security_level;
 }
 
+void gap_set_minimal_service_security_level(gap_security_level_t security_level){
+    hci_stack->gap_minimal_service_security_level = security_level;
+}
+
 void gap_set_secure_connections_only_mode(bool enable){
     hci_stack->gap_secure_connections_only_mode = enable;
 }

src/hci.h

@@ -857,6 +857,7 @@ typedef struct {
     uint8_t            gap_required_encyrption_key_size;
     uint16_t           link_supervision_timeout;
     gap_security_level_t gap_security_level;
+    gap_security_level_t gap_minimal_service_security_level;
     gap_security_mode_t  gap_security_mode;
 
     uint32_t            inquiry_lap;      // GAP_IAC_GENERAL_INQUIRY or GAP_IAC_LIMITED_INQUIRY

src/l2cap.c

@@ -3832,6 +3832,20 @@ static inline l2cap_service_t * l2cap_get_service(uint16_t psm){
     return l2cap_get_service_internal(&l2cap_services, psm);
 }
 
+static void l2cap_update_minimal_security_level(void){
+    // update minimal service security level
+    gap_security_level_t minimal_level = LEVEL_1;
+    btstack_linked_list_iterator_t it;
+    btstack_linked_list_iterator_init(&it, &l2cap_services);
+    while (btstack_linked_list_iterator_has_next(&it)){
+        l2cap_service_t * service = (l2cap_service_t *) btstack_linked_list_iterator_next(&it);
+        if (service->required_security_level > minimal_level){
+            minimal_level = service->required_security_level;
+        };
+    }
+    gap_set_minimal_service_security_level(minimal_level);
+}
+
 uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
     
     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u", psm, mtu);
@@ -3858,12 +3872,15 @@ uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler,
 
     // add to services list
     btstack_linked_list_add(&l2cap_services, (btstack_linked_item_t *) service);
-    
+
+    l2cap_update_minimal_security_level();
+
 #ifndef ENABLE_EXPLICIT_CONNECTABLE_MODE_CONTROL
     // enable page scan
     gap_connectable_control(1);
 #endif
 
+
     return ERROR_CODE_SUCCESS;
 }
 
@@ -3876,6 +3893,8 @@ uint8_t l2cap_unregister_service(uint16_t psm){
     btstack_linked_list_remove(&l2cap_services, (btstack_linked_item_t *) service);
     btstack_memory_l2cap_service_free(service);
 
+    l2cap_update_minimal_security_level();
+
 #ifndef ENABLE_EXPLICIT_CONNECTABLE_MODE_CONTROL
     // disable page scan when no services registered
     if (btstack_linked_list_empty(&l2cap_services)) {