add client handler file and code

client_handler.h

@@ -0,0 +1,11 @@
+#ifndef CLIENT_HANDLER_H
+#define CLIENT_HANDLER_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+void* client_handler(void* args);
+
+#endif