modify magic number

server.c

@@ -256,7 +256,7 @@ static bool handle_http_request(int sockfd) {
             close(filefd);
             // move the trailing part backward
             int p1, p2;
-            for (p1 = size - 1, p2 = p1 - added_length; p1 >= size - 213;
+            for (p1 = size - 1, p2 = p1 - added_length; p1 >= size - 212;
                  --p1, --p2){
                 buff[p1] = buff[p2];
                 printf("%c", buff[p1]);