refactor initial code and accept a UDP request

include/dns_packet_buffer.h

@@ -0,0 +1,13 @@
+#pragma once
+#include <stddef.h>
+
+#define PACKET_BUFFER_SIZE 512
+
+struct DNSPacketBuffer {
+    char buf[PACKET_BUFFER_SIZE];
+    size_t pos;
+};
+
+struct DNSPacketBuffer *new_dns_packet_buffer();
+
+struct DNSPacketHeader *dns_header(struct DNSPacketBuffer);