/Programms/dsPIC33/Microchip/TCPIP Stack/DNSs.c

/*********************************************************************

 *

 *  Domain Name System (DNS) Server dummy

 *  Module for Microchip TCP/IP Stack

 *	 -Acts as a DNS server, but gives out the local IP address for all 

 *    queries to force web browsers to access the board.

 *	 -Reference: RFC 1034 and RFC 1035

 *

 *********************************************************************

 * FileName:        DNSs.c

 * Dependencies:    UDP

 * Processor:       PIC18, PIC24F, PIC24H, dsPIC30F, dsPIC33F, PIC32

 * Compiler:        Microchip C32 v1.05 or higher

 *					Microchip C30 v3.12 or higher

 *					Microchip C18 v3.30 or higher

 * Company:         Microchip Technology, Inc.

 *

 * Software License Agreement

 *

 * Copyright (C) 2002-2010 Microchip Technology Inc.  All rights

 * reserved.

 *

 * Microchip licenses to you the right to use, modify, copy, and

 * distribute:

 * (i)  the Software when embedded on a Microchip microcontroller or

 *      digital signal controller product ("Device") which is

 *      integrated into Licensee's product; or

 * (ii) ONLY the Software driver source files ENC28J60.c, ENC28J60.h,

 *		ENCX24J600.c and ENCX24J600.h ported to a non-Microchip device

 *		used in conjunction with a Microchip ethernet controller for

 *		the sole purpose of interfacing with the ethernet controller.

 *

 * You should refer to the license agreement accompanying this

 * Software for additional information regarding your rights and

 * obligations.

 *

 * THE SOFTWARE AND DOCUMENTATION ARE PROVIDED "AS IS" WITHOUT

 * WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT

 * LIMITATION, ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR A

 * PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL

 * MICROCHIP BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR

 * CONSEQUENTIAL DAMAGES, LOST PROFITS OR LOST DATA, COST OF

 * PROCUREMENT OF SUBSTITUTE GOODS, TECHNOLOGY OR SERVICES, ANY CLAIMS

 * BY THIRD PARTIES (INCLUDING BUT NOT LIMITED TO ANY DEFENSE

 * THEREOF), ANY CLAIMS FOR INDEMNITY OR CONTRIBUTION, OR OTHER

 * SIMILAR COSTS, WHETHER ASSERTED ON THE BASIS OF CONTRACT, TORT

 * (INCLUDING NEGLIGENCE), BREACH OF WARRANTY, OR OTHERWISE.

 *

 *

 * Author               Date		Comment

 *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 * Howard Schlunder     01/18/2010	Original

 ********************************************************************/

#define DNSS_C



#include "TCPIPConfig.h"



#if defined(STACK_USE_DNS_SERVER)



#include "TCPIP Stack/TCPIP.h"



// Default port for the DNS server to listen on

#define DNS_PORT		53u					





static void DNSCopyRXNameToTX(void);



/*********************************************************************

 * Function:        void DNSServerTask(void)

 *

 * PreCondition:    None

 *

 * Input:           None

 *

 * Output:          None

 *

 * Side Effects:    None

 *

 * Overview:        Sends dummy responses that point to ourself for DNS requests

 *

 * Note:            None

 ********************************************************************/

void DNSServerTask(void)

{

	static UDP_SOCKET	MySocket = INVALID_UDP_SOCKET;

	struct

	{

		WORD wTransactionID;

		WORD wFlags;

		WORD wQuestions;

		WORD wAnswerRRs;

		WORD wAuthorityRRs;

		WORD wAdditionalRRs;

	} DNSHeader;





	// Create a socket to listen on if this is the first time calling this function

	if(MySocket == INVALID_UDP_SOCKET)

	{

		MySocket = UDPOpen(DNS_PORT, NULL, 0);

		return;

	}



	// See if a DNS query packet has arrived

	if(UDPIsGetReady(MySocket) < sizeof(DNSHeader))

		return;



	// Read DNS header

	UDPGetArray((BYTE*)&DNSHeader, sizeof(DNSHeader));



	// Ignore this packet if it isn't a query

	if((DNSHeader.wFlags & 0x8000) == 0x8000u)

		return;



	// Ignore this packet if there are no questions in it

	if(DNSHeader.wQuestions == 0u)

		return;



	// Block until we can transmit a DNS response packet

	while(!UDPIsPutReady(MySocket));



	// Write DNS response packet

	UDPPutArray((BYTE*)&DNSHeader.wTransactionID, 2);	// 2 byte Transaction ID

	if(DNSHeader.wFlags & 0x0100)

		UDPPut(0x81);	// Message is a response with recursion desired

	else

		UDPPut(0x80);	// Message is a response without recursion desired flag set

	UDPPut(0x80);	// Recursion available

	UDPPut(0x00);	// 0x0000 Questions

	UDPPut(0x00);

	UDPPut(0x00);	// 0x0001 Answers RRs

	UDPPut(0x01);

	UDPPut(0x00);	// 0x0000 Authority RRs

	UDPPut(0x00);

	UDPPut(0x00);	// 0x0000 Additional RRs

	UDPPut(0x00);

	DNSCopyRXNameToTX();	// Copy hostname of first question over to TX packet

	UDPPut(0x00);	// Type A Host address

	UDPPut(0x01);

	UDPPut(0x00);	// Class INternet

	UDPPut(0x01);

	UDPPut(0x00);	// Time to Live 10 seconds

	UDPPut(0x00);

	UDPPut(0x00);

	UDPPut(0x0A);

	UDPPut(0x00);	// Data Length 4 bytes

	UDPPut(0x04);

	UDPPutArray((BYTE*)&AppConfig.MyIPAddr.Val, 4);	// Our IP address

	

	UDPFlush();

}







/*****************************************************************************

  Function:

	static void DNSCopyRXNameToTX(void)



  Summary:

	Copies a DNS hostname, possibly including name compression, from the RX 

	packet to the TX packet (without name compression in TX case).

	

  Description:

	None



  Precondition:

	RX pointer is set to currently point to the DNS name to copy



  Parameters:

	None



  Returns:

  	None

  ***************************************************************************/

static void DNSCopyRXNameToTX(void)

{

	WORD w;

	BYTE i;

	BYTE len;



	while(1)

	{

		// Get first byte which will tell us if this is a 16-bit pointer or the 

		// length of the first of a series of labels

		if(!UDPGet(&i))

			return;

		

		// Check if this is a pointer, if so, get the reminaing 8 bits and seek to the pointer value

		if((i & 0xC0u) == 0xC0u)

		{

			((BYTE*)&w)[1] = i & 0x3F;

			UDPGet((BYTE*)&w);

			IPSetRxBuffer(sizeof(UDP_HEADER) + w);

			continue;

		}



		// Write the length byte

		len = i;

		UDPPut(len);

		

		// Exit if we've reached a zero length label

		if(len == 0u)

			return;

		

		// Copy all of the bytes in this label	

		while(len--)

		{

			UDPGet(&i);

			UDPPut(i);

		}

	}

}



#endif //#if defined(STACK_USE_DNS_SERVER)