modbus_tcp

add lwip_strerr
fix tcp_close

tests/mocs.c

@@ -141,10 +141,11 @@ void tcp_poll(void* pcb, void* poll, uint8_t interval) {
     dprint("tcp_poll\n");
 }
 
-void tcp_close(void* pcb) {
+err_t tcp_close(void* pcb) {
     UNUSED(pcb);
 
     dprint("tcp_close\n");
+    return ERR_OK;
 }
 
 void tcp_write(void* pcb, const char* data, size_t len, uint8_t apiflags) {
@@ -185,4 +186,11 @@ void pbuf_free(struct pbuf* p) {
 uint16_t pbuf_copy_partial(const struct pbuf* buf, void* dataptr, uint16_t len, uint16_t offset) {
     memcpy(dataptr, ((uint8_t*)(buf->payload)) + offset, len);
     return len;
+}
+
+const char* lwip_strerr(err_t err) {
+    UNUSED(err);
+
+    dprint("lwip_sterr\n");
+    return NULL;
 }