implemented cb_addnode in the quad_app library

quad/src/quad_app/callbacks.c

 #include "communication.h"
 #include "commands.h"
+#include "graph_blocks.h"
 #include "type_def.h"
 #include "computation_graph.h"
 #include "util.h"
@@ -382,10 +383,29 @@ int cb_getnodes(struct modular_structs *structs, struct metadata *meta, unsigned
  * |-----------------------------|
  */
 int cb_addnode(struct modular_structs *structs, struct metadata *meta, unsigned char *data, unsigned short length) {
-	const struct computation_graph* graph = structs->parameter_struct.graph;
+	// Check if the data length is large enough
 	if (length < 2) {return -1;}
+
 	// Size of name
 	size_t name_len = length - 2;
+	struct computation_graph* graph = structs->parameter_struct.graph;
+	char resp_buf[2];
 
+	int16_t node_type = build_short(data);
+	if (node_type < 0 && node_type >= MAX_BLOCK_TYPES) {
+		pack_short(-1, resp_buf);
+		send_data(&structs->hardware_struct.uart, RESPADDNODE_ID, meta->msg_id, resp_buf, 2);
+		return -1;
+	}
+
+	char* name = strndup(data+2, name_len);
+	int new_block_id = graph_add_defined_block(graph, node_type, name);
+	free(name);
+	// Format the response data
+	// New Block Id
+	pack_short(new_block_id, resp_buf);
+
+	// Send the response
+	send_data(&structs->hardware_struct.uart, RESPADDNODE_ID, meta->msg_id, resp_buf, 2);
 	return 0;
 }