dns.h

Dns查询Mx记录的源代码。

	{
		NS = Buffer.GetName(0);
	}

	virtual CString ToString()
	{
		CString Text;
		Text += "NS Record:\n";
		Text += CDnsRR::ToString();
		Text += "NS=" + NS + "\n";
		return Text;
	}

	virtual void CopyRData(CDnsRR* pRR){
		CDnsRRNS * pRRNS = (CDnsRRNS*) pRR;
		NS = pRRNS->NS;
	}
};



















/************************************************************************
		 
		 Name   : CDnsQueryType
		 Type   : Class
------------------------------------------------------------------------
		 Author : Akash Kava
		 Purpose: Returns int type number from string representation of type
		          Also returns new Resource Record Class Pointer
		          
		          This static function makes new object of specified type
		          and also copies contents of CDnsRR to type dependent
		          resource record object
************************************************************************/
class CDnsQueryType{
public:
	static int GetType( CString Name )
	{
		Name.MakeUpper();
		
		if(Name == "A")
			return 1;
		
		if(Name == "NS")
			return 2;

		if(Name == "MD")
			return 3;

		if(Name == "MF")
			return 4;

		if(Name == "CNAME")
			return 5;

		if(Name == "SOA")
			return 6;

		if(Name == "MB")
			return 7;

		if(Name == "MG")
			return 8;

		if(Name == "MR")
			return 9;

		if(Name == "NULL")
			return 10;

		if(Name == "WKS")
			return 11;

		if(Name == "PTR")
			return 12;

		if(Name == "HINFO")
			return 13;

		if(Name == "MINFO")
			return 14;

		if(Name == "MX")
			return 15;

		if(Name == "TXT")
			return 16;

		return -1;
	}

	static CDnsRR * GetNewRecord(CDnsRR * pRR)
	{
		switch(pRR->Type)
		{
		case 1:
			return new CDnsRRA(pRR);
		case 2:
			return new CDnsRRNS(pRR);
		case 5:
			return new CDnsRRCNAME(pRR);
		case 15:
			return new CDnsRRMX(pRR);

			// Rest you implement if you need it !! he he

		default:
			return new CDnsRRDefault(pRR);
		}
	}
};










/************************************************************************
		 
		 Name   : CDnsQuery
		 Type   : Class
------------------------------------------------------------------------
		 Author : Akash Kava
		 Purpose: Dns Query Class
************************************************************************/
class CDnsQuery{
public:
	CStringList			Names;
	unsigned __int16	Type;
	unsigned __int16	Class;

	CDnsQuery( LPCTSTR lpszHost , LPCTSTR lpszType )
	{
		CString host(lpszHost);
		int i;
		do
		{
			i = host.Find('.');
			if(i != -1)
			{
				Names.AddTail(host.Mid(0,i));
				host = host.Mid(i+1);
			}
			else
			{
				Names.AddTail(host);
				break;
			}
		}while(true);

		Type = CDnsQueryType::GetType(lpszType);
		Class = 1;
	}

	CDnsBuffer Pack()
	{

		CDnsBuffer Buffer;

		POSITION Pos = Names.GetHeadPosition();
		while(Pos)
		{
			CString Name = Names.GetNext(Pos);
			unsigned __int8 Len = Name.GetLength();
			Buffer << Len;
			Buffer.Append((unsigned char *)(LPCTSTR)Name,Len);

		}

		unsigned __int8 n = 0;
		Buffer << n;

		Buffer << Type;
		Buffer << Class;
		return Buffer;
	}

	void Unpack( CDnsBuffer & Buffer )
	{
		CString Name = Buffer.GetName(0);
		Buffer >> Type;
		Buffer >> Class;

	}
};











/************************************************************************
		 
		 Name   : CDnsRRPtrList
		 Type   : Class
------------------------------------------------------------------------
		 Author : Akash Kava
		 Purpose: All Resource Records are hold in a CList class which holds 
		          pointers of all objects. And also implements CHostSearch 
		          and returns IP address found in A records if any

				  Users who use the record pointer are requested to keep
				  copy of Resource Record according to type because when
				  This clas gets destroys it deletes its pointers !!
************************************************************************/
class CDnsRRPtrList :public  CList<CDnsRR*,CDnsRR*>{
public:

	~CDnsRRPtrList ()
	{
		while(!IsEmpty())
		{
			CDnsRR * pRR = RemoveHead();
			delete pRR;
		}
	}

};







/************************************************************************
		 
		 Name   : CDnsClient
		 Type   : Class
------------------------------------------------------------------------
		 Author : Akash Kava
		 Purpose: The final DnsClient class
		          
		          It can be used in 2 ways.
		          
		          1) Directly Query MX records and CStringList by calling 
		          static member function. No hastle of pointer management.
		          
		          2) Call another static function Get to get result of type 
				  requested The CDnsRRPtrList supplied gets all required 
				  resource records. It searches recursivly of found names 
				  servers so you dont need to worry about nameservers 
				  returned in query. What you will get is the final result 
				  after 10 tries. Or else domain does not exist.
		              The list returned has pointers to CDnsRR derived class
		          depending upon type. While using it, please copy the 
				  relevant content and then processing because everything 
				  will get destroyed as soon as CDnsRRPtrList goes out of 
				  scope.
		          
		          2) Create Object of class and query, you will need to do all 
		          recursive nameserver processing etc so just forget it.
************************************************************************/
class CDnsClient{
public:

	CString				Log;
	CSocketClient		Client;
	CDnsBuffer			Buffer;

	int					QueryType;
	CDnsHeader			Header;
	CDnsRRPtrList		Questions;
	CDnsRRPtrList		Answers;
	CDnsRRPtrList		Authorities;
	CDnsRRPtrList		Additionals;

	
	BOOL Query(LPCTSTR lpszServer, LPCTSTR lpszHost, LPCTSTR lpszType)
	{

		try
		{

			unsigned __int16 size;

			// Build The query
			CDnsQuery Query(lpszHost,lpszType);


			// Make the Buffer
			Buffer += Header.Pack();
			Buffer += Query.Pack();


			// Try to connect to server, if failed, will give an exception
			Client.ConnectTo(lpszServer,53);

			
			// Write Buffer to end client
			size = Buffer.GetSize();
			Client.WriteInt16(size);
			Client.WriteBytes(Buffer.GetBuffer(),Buffer.GetSize());


			// Dns Response send buffer length first, read it
			// then read buffer
			size = Client.ReadInt16();
			Client.ReadBytes(Buffer.GetBufferSetLength(size),size);


			// Cool now Socket is not needed, close it
			Client.Close();

			// Put Buffer's pointer to 0 and start reading things now.
			Buffer.Reset(0);


			// First Extract Header from buffer
			Header.Unpack(Buffer);

			// Dns Query is sent again by server, uselessly..
			// Extract it, what else we an do...
			Query.Unpack(Buffer);
			QueryType = Query.Type;

			

			// Read rest of Records
			GetRecords(Answers,Header.ANCount);
			GetRecords(Authorities,Header.NSCount);
			GetRecords(Additionals,Header.ARCount);

			return true;
		}
		catch(CSocketException * pE)
		{
			Log += pE->m_strError + "\n";
			return false;
		}
	}


	void GetRecords( CDnsRRPtrList & List , int Total )
	{
		if(Total==0)
			return;
		for(int i=0;i<Total;i++)
		{
			CDnsRR RR;
			RR.Unpack(Buffer);

			CDnsRR * pRR = CDnsQueryType::GetNewRecord(&RR);

			pRR->Unpack(Buffer);

			List.AddTail(pRR);
			TRACE0(pRR->ToString());
		}
	}





	/************************************************************************
			 FUNCTION
			 Name   : Get
			 Author : Akash Kava
			 Purpose: Call this function to retrive answers of query, this function
					  does recursive processing upto specified number of trials
					  
					  While calling this function, please pass the Reference parameters
					  as explained
	========================================================================
			 Params : Server	: Name of the name server to connect
					  Name		: Domain name to query
					  Type		: Type of query, case insensitive, MX or mx
					  Answers	: Resource Record Object List , please pass empty 
									List here, it will return all answers
					  Additional: Resource Record Object List, please pass empty
									List here , it will pass additional A record entries
					  NSTried	: Please pass empty CStringList here
					  Log		: Please pass empty CString here
					  nTries	: Make sure you pass atleast 5 trials
	------------------------------------------------------------------------
			 Returns: True if successful , false if failed
	************************************************************************/
	static BOOL Get(
					LPCTSTR lpszServer,		
					LPCTSTR lpszName,		
					LPCTSTR lpszType,		
			CDnsRRPtrList&	Answers,	
			CDnsRRPtrList&	Additionals,
			CStringList&	NSTried,	
				CString&	Log,		
					int&	nTries		
					)
	{

		
		if(lpszServer==NULL)
		{
			// If you dont specify servers then try root servers.. too costly!!!


			if(Get("A.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
			nTries = 10;
			if(Get("B.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("C.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("D.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("E.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("F.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("G.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("H.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			nTries = 10;
			if(Get("I.GTLD-SERVERS.net",lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
				return true;
			if(nTries==0)
				return false;

		
	
			return false;
		}

		
		// Tries over, fine, return true to indicate end of process
		if(nTries<=0)
		{
			Log += lpszName;
			Log += " Domain Does not exist Probably\n";
			return true;
		}


		nTries--;

		
		// Resolve DNS
		CDnsClient Client;
		if(!Client.Query(lpszServer,lpszName,lpszType))
			return false;


		// Found Answers, cool, Make a copy and return
		if(Client.Answers.GetCount()!=0)
		{
			POSITION Pos = Client.Answers.GetHeadPosition();
			while(Pos)
			{
				CDnsRR * pRR = (CDnsRR*) Client.Answers.GetNext(Pos);

				// Allocate new Record from CDnsQueryType and also copy initial content
				//		that is without RData
				CDnsRR * pNewRR = CDnsQueryType::GetNewRecord(pRR);

				// Copy RData to new object
				pNewRR->CopyRData(pRR);

				// Add it to Answer List
				Answers.AddTail(pNewRR);
			}


			// Add additional entries from here of all A records only
			Pos = Client.Additionals.GetHeadPosition();
			while(Pos)
			{
				CDnsRR * pRR = Client.Additionals.GetNext(Pos);
				if(pRR->Type == 1)
				{

					// Allocate new record from CDnsQueryType and also copy
					//      initiail conent without RData
					CDnsRR * pNewRR = CDnsQueryType::GetNewRecord(pRR);

					// Copy RData to new object
					pNewRR->CopyRData(pRR);

					Additionals.AddTail(pNewRR);
				}
			}
			return true;
		}


		// If the Name Server we queried is already authorized
		// return true, may be domain expired !!
		if(Client.Header.Flags.Flags.AA == 1)
			return true;


		// Recursive Query , The DNS client returns NS records
		// which contains name server information, get it and
		// query them to find answer
		POSITION Pos = Client.Authorities.GetHeadPosition();
		while(Pos)
		{
			CDnsRRNS * pRRNS = (CDnsRRNS *)Client.Authorities.GetNext(Pos);
			
			// Choose only Name Servers , or else goto next
			if(pRRNS->Type != 2)
				continue;

			// Get IP , put less load on System DNS Resolver, forget it now..
			//CString NS = Client.Additionals.GetHostIP(pRRNS->NS);
			CString NS = pRRNS->NS;


			// Make sure you visit Name server only once
			// if you have already tried then leave, goto next
			if(NSTried.Find(NS)!=NULL)
				continue;

			// Add this name server into Tried List
			NSTried.AddTail(NS);


			// If recursive query returns true then return true,
			// either it was successful
			// or it gave empty result and domain expired
			if(Get(NS,lpszName,lpszType,Answers,Additionals,NSTried,Log,nTries))
			{
				return true;
			}

			// In case there are any resource records in answer
			// go and return true
			if(!Answers.IsEmpty())
				return true;

		}

		// Even if you didnt find anything in Name servers
		// might be cilent couldnt connect to name server
		// try next, just return false
		return false;
	}



	

	// whooooooo baby, the most important , MX search
	// Just searches the MX of domain, returns IP address only,
	// however you can use Get function to get detailed MX records
	// CStringList receives all host addresses for MX
	static CString GetMX(LPCTSTR lpszServer,LPCTSTR lpszHost,CStringList & List)
	{

		List.RemoveAll();

		CString Log;
		CStringList NSTried;
		int nTries=10;

		CDnsRRPtrList Answers;
		CDnsRRPtrList Additionals;

		if(Get(lpszServer,lpszHost,"MX",Answers,Additionals,NSTried,Log,nTries))
		{
			Log.Empty();
			while(!Answers.IsEmpty())
			{
				CDnsRRMX * pRR = (CDnsRRMX*)Answers.RemoveHead();
				
				SearchARecords(pRR->Exchange,Additionals,List);

				Log += pRR->ToString();
				delete pRR;
			}
		}
		
		return Log;
	}


	static void SearchARecords( CString & Domain , CDnsRRPtrList & Additionals, CStringList & IPList)
	{

		BOOL bFound = false;

		POSITION Pos = Additionals.GetHeadPosition();
		while(Pos)
		{
			CDnsRR * pRR = (CDnsRR*) Additionals.GetNext(Pos);
			if(pRR->Type!=1)
				continue;

			CDnsRRA * pRRA = (CDnsRRA*) pRR;
			if(pRRA->Name.CompareNoCase(Domain)==0)
			{
				IPList.AddTail(pRRA->A);
				bFound = true;
			}
		}

		if(!bFound)
			IPList.AddTail(Domain);
	}

};

#endif