FreeRTOS_DNS.c

/*
 * FreeRTOS+TCP V2.0.11
 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://aws.amazon.com/freertos
 * http://www.FreeRTOS.org
 */

/* Standard includes. */
#include <stdint.h>

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "list.h"
#include "semphr.h"

/* FreeRTOS+TCP includes. */
#include "FreeRTOS_IP.h"
#include "FreeRTOS_Sockets.h"
#include "FreeRTOS_IP_Private.h"
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_DNS.h"
#include "NetworkBufferManagement.h"
#include "NetworkInterface.h"
#include "IPTraceMacroDefaults.h"

/* Exclude the entire file if DNS is not enabled. */
#if( ipconfigUSE_DNS != 0 )

#if( ipconfigBYTE_ORDER == pdFREERTOS_LITTLE_ENDIAN )
	#define dnsDNS_PORT						0x3500
	#define dnsONE_QUESTION					0x0100
	#define dnsOUTGOING_FLAGS				0x0001 /* Standard query. */
	#define dnsRX_FLAGS_MASK				0x0f80 /* The bits of interest in the flags field of incoming DNS messages. */
	#define dnsEXPECTED_RX_FLAGS			0x0080 /* Should be a response, without any errors. */
#else
	#define dnsDNS_PORT						0x0035
	#define dnsONE_QUESTION					0x0001
	#define dnsOUTGOING_FLAGS				0x0100 /* Standard query. */
	#define dnsRX_FLAGS_MASK				0x800f /* The bits of interest in the flags field of incoming DNS messages. */
	#define dnsEXPECTED_RX_FLAGS			0x8000 /* Should be a response, without any errors. */

#endif /* ipconfigBYTE_ORDER */

/* The maximum number of times a DNS request should be sent out if a response
is not received, before giving up. */
#ifndef ipconfigDNS_REQUEST_ATTEMPTS
	#define ipconfigDNS_REQUEST_ATTEMPTS		5
#endif

/* If the top two bits in the first character of a name field are set then the