set ip type of service to set specific precedence for QoS

connectivity/lwipstack/source/LWIPStack.cpp

@@ -664,6 +664,12 @@ nsapi_error_t LWIP::setsockopt(nsapi_socket_t handle, int level, int optname, co
             return err_remap(igmp_err);
         }
 
+        case NSAPI_IPTOS:
+            if (optlen != sizeof(int)) {
+                 return NSAPI_ERROR_UNSUPPORTED;
+            }
+            s->conn->pcb.ip->tos = (u8_t)(*(const int *)optval);
+            return 0;
         default:
             return NSAPI_ERROR_UNSUPPORTED;
     }

connectivity/netsocket/include/netsocket/nsapi_types.h

@@ -272,6 +272,7 @@ typedef enum nsapi_socket_option {
     NSAPI_BIND_TO_DEVICE,    /*!< Bind socket network interface name*/
     NSAPI_LATENCY,           /*!< Read estimated latency to destination */
     NSAPI_STAGGER,           /*!< Read estimated stagger value to destination */
+    NSAPI_IPTOS,             /*!< Set IP type of service to set specific precedence */
 } nsapi_socket_option_t;
 
 typedef enum nsapi_tlssocket_level {