--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tcpiputils/dnd/src/dns.cpp	Tue Jan 26 15:23:49 2010 +0200
@@ -0,0 +1,1213 @@
+// Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// dns.cpp - the main client module of the DNS.
+//
+
+#include <e32math.h>
+#include <in_sock.h>
+#include <in6_opt.h>
+#include "dns.h"
+#include "dnd.hrh"		// EDndDump
+#include <networking/dnd_err.h>
+#include "engine.h"
+#include "servers.h"
+#include "cache.h"
+#include "inet6log.h"
+#ifdef LLMNR_ENABLED
+#	include "llmnrresponder.h"
+#endif
+#include "dnd_ini.h"
+
+#ifdef EXCLUDE_SYMBIAN_DNS_PUNYCODE
+#undef SYMBIAN_DNS_PUNYCODE
+#endif //EXCLUDE_SYMBIAN_DNS_PUNYCODE
+
+class CDnsService : public CDndDnsclient
+	{
+public:
+	CDnsService(CDndEngine &aControl, MDnsServerManager &aServerManager) : CDndDnsclient(aControl, aServerManager) {}
+	void ConstructL();
+	~CDnsService();
+	virtual void ConfigurationChanged();
+
+	TInt SetHostName(TUint32 aId, const THostName &aName);
+	TInt GetHostName(TUint32 aId, THostName &aName, MDnsResolver &aCallback);
+
+	TInt GetByAddress(TUint32 aId, const TInetAddr &aAddr, TInt aNext, THostName &aName);
+	TInt GetByName(TUint32 aId, const THostName &aName, TInt aNext, TInetAddr &aAddr);
+private:
+#ifdef LLMNR_ENABLED
+	CDndLlmnrResponder *iLlmnrResponder; //< Pointer to the LLMNR responder object
+#endif
+	TUint32 GetNetId(TUint32 aIndex);
+	TInetAddressInfo *GetAddressList(TInt &aN);
+	};
+
+
+void CDnsService::ConstructL()
+	{
+	CDndDnsclient::ConstructL();
+#ifdef LLMNR_ENABLED
+	iLlmnrResponder = new (ELeave) CDndLlmnrResponder(iControl, iServerManager, iHostNames);
+	iLlmnrResponder->ConstructL();
+#endif
+	}
+
+CDnsService::~CDnsService()
+	{
+#ifdef LLMNR_ENABLED
+	delete iLlmnrResponder;
+#endif
+	}
+	
+
+void CDnsService::ConfigurationChanged()
+	{
+#ifdef LLMNR_ENABLED
+	iLlmnrResponder->ConfigurationChanged();
+#endif
+	}
+//
+// Gateway hostname processing to the responder
+//
+TInt CDnsService::SetHostName(TUint32 aId, const THostName &aName)
+	{
+	const TInt res = iHostNames.Map(aId, aName);
+#ifdef LLMNR_ENABLED
+	return res == KErrNone ? iLlmnrResponder->SetHostName(aId, iHostNames.Find(aId)) : res;
+#else
+	return res;
+#endif
+	}
+
+TInt CDnsService::GetHostName(TUint32 aId, THostName &aName, MDnsResolver &aCallback)
+	{
+	aName = iHostNames.Find(aId);
+#ifdef LLMNR_ENABLED
+	return iLlmnrResponder->GetHostName(aId, aCallback);
+#else
+	(void)aCallback;
+	return KErrNone;
+#endif
+	}
+
+
+
+TUint32 CDnsService::GetNetId(TUint32 aIndex)
+	{
+	TPckgBuf<TSoInetIfQuery> opt;
+	opt().iIndex = aIndex;
+	return iControl.iSocket.GetOpt(KSoInetIfQueryByIndex, KSolInetIfQuery, opt) == KErrNone
+		? opt().iZone[15] : 0;
+	}
+
+TInetAddressInfo *CDnsService::GetAddressList(TInt &aN)
+	/**
+	* Returns a list of all current addresses.
+	*
+	* @retval aN	The number of addresses (if return is non-NULL).
+	* @return		The address list, or NULL if not available.
+	*
+	* The returned address list must be freed by the caller
+	* as "delete[] list".
+	*/
+	{
+	TPtr8 empty(NULL, 0);
+	aN = iControl.iSocket.GetOpt(KSoInetAddressInfo, KSolInetIfQuery, empty);
+	if (aN <= 0)
+		return NULL;
+	TInetAddressInfo *p = new TInetAddressInfo[aN];
+	if (p == NULL)
+		return NULL;	// No memory available.
+	TPtr8 opt((TUint8 *)p, aN*sizeof(TInetAddressInfo));
+	aN = iControl.iSocket.GetOpt(KSoInetAddressInfo, KSolInetIfQuery, opt);
+	if (aN < 0)
+		aN = 0;
+	else
+		aN = opt.Length() / (TInt)sizeof(TInetAddressInfo);
+	return p;
+	}
+
+
+TInt CDnsService::GetByAddress(TUint32 /*aId*/, const TInetAddr &aAddr, TInt /*aNext*/, THostName &aName)
+	/**
+	* Returns the local hostname, if address is my own.
+	*/
+	{
+	TPckgBuf<TSoInetIfQuery> opt;
+	opt().iSrcAddr = aAddr;
+	if (iControl.iSocket.GetOpt(KSoInetIfQueryBySrcAddr, KSolInetIfQuery, opt) != KErrNone)
+		return KErrNotFound;
+	aName = iHostNames.Find(opt().iZone[15]);	// Locate hostname for network id.
+	return (aName.Length() > 0) ? KErrNone : KErrNotFound;
+	}
+
+TInt CDnsService::GetByName(TUint32 aId, const THostName &aName, TInt /*aNext*/, TInetAddr &aAddr)
+	/**
+	* Returns one of my own addresses, if the hostname is local.
+	*/
+	{
+	const TDesC &name = iHostNames.Find(aId);
+	if (aName.Length() > 0 && name.CompareF(aName) != 0)
+		return KErrNotFound;	// The query name is not a local host.
+	//
+	// Locate a local addres from some interface within the specific network.
+	//
+	TInt N;
+	TInetAddressInfo *list = GetAddressList(N);
+	if (list == NULL)
+		return KErrNotFound;
+
+	TUint32 iface = 0;
+	TUint32 netid = 0;
+	TInt scope = -1;
+	TInt best = 0;
+	for (TInt i = 0; i < N; ++i)
+		{
+		if (list[i].iState != TInetAddressInfo::EAssigned)
+			continue;
+		if (list[i].iInterface != iface)
+			{
+				iface = list[i].iInterface;
+				netid = GetNetId(iface);
+			}
+		if (netid != aId)
+			continue;	// Not this address.
+		if (list[i].iAddress.Scope() > scope)
+			{
+			scope = list[i].iAddress.Scope();
+			best = i;
+			}
+		}
+	aAddr.SetAddress(list[best].iAddress);
+	aAddr.SetScope(list[best].iScopeId);
+	delete[] list;
+	return scope < 0 ? KErrNotFound : KErrNone;
+	}
+
+//
+//
+
+CDndDnsclient *CDndDnsclient::NewL(CDndEngine &aControl, MDnsServerManager &aServerManager)
+	{
+	LOG(Log::Printf(_L("CDndDnsclient::NewL()")));
+
+	CDnsService *const dns = new (ELeave) CDnsService(aControl, aServerManager);
+	CleanupStack::PushL(dns);
+	dns->ConstructL();
+	CleanupStack::Pop();
+	return dns;
+	}
+
+CDndDnsclient::CDndDnsclient(CDndEngine &aControl, MDnsServerManager &aServerManager)
+	: CDnsSocket(aControl.GetConfig().iEDNS0), iControl(aControl), iServerManager(aServerManager)
+	{
+	}
+
+void CDndDnsclient::ConstructL()
+	{
+	LOG(Log::Printf(_L("CDndDnsclient::ConstructL() size=%d"), (TInt)sizeof(*this)));
+	CDnsSocket::ConstructL();
+
+	iCache = new (ELeave) CDndCache();
+	iCache->ConstructL();
+
+	TPtrC localhost;
+	if(iControl.FindVar(DND_INI_HOST, DND_INI_HOSTNAME, localhost))
+		(void)iHostNames.Reset(localhost);
+	else
+		(void)iHostNames.Reset(KDndIni_Hostname);
+	}
+
+
+
+
+void CDndDnsclient::HandleCommandL(TInt aCommand)
+	{
+#ifdef _LOG
+	switch(aCommand)
+		{
+		case EDndDump:
+			if (iCache)
+				iCache->Dump(iControl);
+			break;
+		default:
+			break;
+		}
+#endif
+	if (aCommand == EDndFlush)
+		iCache->Flush();
+	}
+
+CDndDnsclient::~CDndDnsclient()
+	{
+	DeactivateSocket();
+
+	// Just to be sure, cancel server list notifys (if any)
+	// (this means that SERVER MANAGER MUST NOT BE DELETED
+	// before this object!)
+	for (TUint i = 0; i < KDndNumRequests; i++)
+		iServerManager.CloseList(iDndReqData[i].iFilter);
+	delete iCache;
+	}
+
+// CDndDnsclient::CheckAddress
+// ***************************
+TInt CDndDnsclient::CheckAddress(const TInetAddr &aDestination)
+	{
+	TPckgBuf<TSoInetIfQuery> opt;
+	opt().iDstAddr = aDestination;
+	
+	const TInt err = iControl.iSocket.GetOpt(KSoInetIfQueryByDstAddr, KSolInetIfQuery, opt);
+	if (err == KErrNone && TInetAddr::Cast(opt().iSrcAddr).IsUnspecified())
+		return KErrNotFound;	// No route or source address.
+	return err;
+	}
+
+
+
+// TDndReqData::PickDefaultServer
+// ********************************
+TBool TDndReqData::PickDefaultServer()
+	{
+	TInetAddr tmp;
+	TBool ret = FALSE;
+
+	if (iCurrentServer == 0)
+		ret = iOwner->iServerManager.OpenList(iFilter, this) > 0;
+	iOwner->iCache->GetServerAddress(iOwner->iServerManager.NameSpace(iFilter, iCurrentServer), tmp);
+	iFilter.iServerId = iOwner->iServerManager.ServerId(tmp);
+	iCurrentServer = iOwner->iServerManager.Next(iFilter, 0);
+#ifdef _LOG
+	if (iCurrentServer)
+		Log::Printf(_L("\t\tDNS session [%u] default nameserver (id=%d) assigned"), (TInt)this, (TInt)iCurrentServer);
+	else
+		Log::Printf(_L("\t\tDNS session [%u] no nameservers available for this session"), (TInt)this);
+#endif
+	return ret || iCurrentServer != 0;
+	}
+
+
+// TDndReqData::PickNewServer
+// ****************************
+TBool TDndReqData::PickNewServer()
+	{
+	if (iCurrentServer == 0)
+		iOwner->iServerManager.BuildServerList();
+	iCurrentServer = iOwner->iServerManager.Next(iFilter, iCurrentServer);
+#ifdef _LOG
+	if (iCurrentServer)
+		Log::Printf(_L("\t\tDNS session [%u] next nameserver (id=%d) assigned"), (TInt)this, (TInt)iCurrentServer);
+	else
+		Log::Printf(_L("\t\tDNS session [%u] next, no alternate nameservers to assign"), (TInt)this);
+#endif
+	return iCurrentServer != 0;
+	}
+
+void TDndReqData::ServerListComplete(const TDnsServerFilter &aFilter, TInt aResult)
+	{
+	if (&aFilter == &iFilter)
+		{
+		iCurrentServer = iOwner->iServerManager.Next(iFilter, 0);
+		if (iIsReqPending)
+			{
+			if (aResult == KErrNone)
+				{
+				if (PickDefaultServer())
+					{
+					iOwner->ReSend(*this);
+					aResult = KDnsNotify_HAVE_SERVERLIST;
+					}
+				else
+					aResult = KErrDndServerUnusable;
+				}
+			SendResponse(aResult);
+			}
+		}
+	}
+
+
+// CDndDnsclient::OpenSession
+// **************************
+/**
+// A session is internally represented by a TDndReqData. Find an unused
+// entry and assign it. Unused entry is recognized by it having no
+// callback function (= NULL).
+*/
+MDnsSession *CDndDnsclient::OpenSession(MDnsResolver *const aCallback)
+	{
+	TUint i;
+	//
+	// Locate available TDndReqData entry...
+	//
+	for (i = 0;; ++i)
+		{
+		if (i >= KDndNumRequests)
+			return NULL;	// No "sessions" available
+		// For now, assume the slot is available, if no callback has been installed
+		if (iDndReqData[i].iCallback == NULL)
+			break;
+		}
+	TDndReqData &rq = iDndReqData[i];
+	rq.iCallback = aCallback;
+	rq.iOwner = this;
+	iActivityCount++;	// Count each open session as "activity".
+	return &rq;
+	}
+
+
+void CDndDnsclient::Error(const TInetAddr &aServer, TInt /*aError*/)
+	{
+	const TUint server_id = iServerManager.ServerId(aServer);
+	if (server_id == 0)
+		return;		// -- nothing to do, address not registered as a server
+
+	//
+	// Try to notify all sessions currently using this server
+	//
+	for (TUint i = 0; i < KDndNumRequests; ++i)
+		{
+		TDndReqData &rq = iDndReqData[i];
+		// For now, assume the slot is in used, if callback has been installed
+		if (rq.iCallback == NULL)
+			continue;
+		if (rq.iCurrentServer == server_id)
+			rq.SendResponse(KErrDndServerUnusable);
+		}
+	}
+
+
+
+// TDndReqData::Close
+// ******************
+void TDndReqData::Close()
+	{
+	CancelQuery();
+	iCallback = NULL;
+	if (iRecord)
+		{
+		iRecord->Unlock(this);
+		iRecord = NULL;
+		}
+	iOwner->iServerManager.CloseList(iFilter);
+	// If this was the last active session, then
+	// cancel all requests 
+	ASSERT(iOwner->iActivityCount > 0);
+	if (--iOwner->iActivityCount == 0)
+		iOwner->DeactivateSocket();
+	}
+
+// TDndReqData::NewQuery
+// ***********************
+TInt TDndReqData::NewQuery(const TDnsMessage &aQuery, TDnsServerScope aServerScope, TUint32 aFlags)
+	{
+	iIsReqPending = FALSE;
+	iIsNewQuery = TRUE;
+	iIsUsingTCP = 0;
+	iQdCount = 1;
+	iFlags = aFlags;
+	iFilter.iServerScope = aServerScope;
+	iFilter.iServerId = 0;
+	iNetworkId = aQuery.iId;  // Get the networkId information from the Query.
+
+#ifdef SYMBIAN_DNS_PUNYCODE
+	if( (aQuery.iScope & 0x80) == 0x80 )
+		{
+		iIdnEnabled = 1;
+		iQuestion.EnableIdn(ETrue);
+		}
+	else 
+		{
+		iIdnEnabled = 0;
+		iQuestion.EnableIdn(EFalse);
+		}
+#endif //SYMBIAN_DNS_PUNYCODE
+
+	switch (aQuery.iType)
+		{
+		case KDnsRequestType_GetByName:
+		case KDnsRequestType_GetByAddress:
+			{
+			const TNameRecord &query = aQuery.NameRecord();
+
+			if (aQuery.iType == KDnsRequestType_GetByName)
+				{
+				iFilter.iLockId = aQuery.iId;
+				iFilter.iLockType = KIp6AddrScopeNetwork;
+#ifdef SYMBIAN_DNS_PUNYCODE
+				TInt err = iQuestion.SetName(query.iName);
+				if( err != KErrNone)
+					{
+					return err;
+					}
+#else
+				iQuestion.SetName(query.iName);
+#endif // SYMBIAN_DNS_PUNYCODE
+				}
+			else
+				{
+				iOwner->iServerManager.LockByAddress(TInetAddr::Cast(query.iAddr), aQuery.iId, iFilter);
+#ifdef SYMBIAN_DNS_PUNYCODE
+				TInt err = iQuestion.SetName(TInetAddr::Cast(query.iAddr));
+				if( err != KErrNone)
+					{
+					return err;
+					}
+#else
+				iQuestion.SetName(TInetAddr::Cast(query.iAddr));
+#endif // SYMBIAN_DNS_PUNYCODE
+				}
+			}
+			break;
+		case KDnsRequestType_TDnsQuery:
+			{
+			const TDnsQuery &query = aQuery.Query();
+			iQuestion.Copy(query.Data());
+			iFilter.iLockId = aQuery.iId;
+			iFilter.iLockType = KIp6AddrScopeNetwork;
+			}
+			break;
+		default:
+			return KErrNotSupported;
+		}
+	iCurrentServer = 0;
+	//
+	// For forward query, the Scope identifier of the aQuery.iAddr is the network id
+	// For pointer query, if the address is not of network scope, then need to find
+	// the network id based on the scope id... (fix later). -- msa
+
+	iOpcode = EDnsOpcode_QUERY;		// Only EStandard supported! (EInverse is not same as PTR query!!!)
+	if (iRecord)
+		{
+		iRecord->Unlock(this);
+		iRecord = NULL;
+		}
+	return KErrNone;
+	}
+
+
+// TDndReqData::CancelQuery
+// **************************
+void TDndReqData::CancelQuery()
+	{
+	iIsReqPending = FALSE;
+	Cancel();
+	iOwner->iServerManager.CloseList(iFilter);
+	}
+
+
+// TDndReqData::DoNext
+// *********************
+/**
+// @retval aReply	returns the requested Resource Record value, if KErrNone return
+// @param aNext		the index of the value to be returned. 0 is the index of the first value
+// @returns
+//	@li	KErrNotFound, if there is no value at specified index
+//	@li	KErrDndCache, if the reply from DNS stored in cache was corrupt
+//	@li	KErrNone, if value successfully returned
+*/
+TInt TDndReqData::DoNext(TDnsMessageBuf &aReply, TInt aNext) const
+	{
+	if (iRecord == NULL)
+		return KErrNotFound;
+	TInt ret = iRecord->ErrorCode();
+	if (ret < 0)
+		return ret;	// No usable record present
+
+	TDndRR tempRR(iRecord->Reply());
+#ifdef SYMBIAN_DNS_PUNYCODE
+		tempRR.iIdnEnabled = TBool(iIdnEnabled);
+#endif //SYMBIAN_DNS_PUNYCODE
+
+	const TInet6HeaderDNS &hdr = iRecord->Header();
+	TInt answerCount = hdr.ANCOUNT();
+
+	ret = tempRR.FindRR(iRecord->AnswerOffset(), answerCount, iQuestion.QType(), iQuestion.QClass(), aNext);
+	if (ret < 0)
+		{
+		if (ret == KErrDndCache)
+			iRecord->Invalidate();
+		return ret;
+		}
+
+	TInetAddr *addr = NULL;
+
+	switch (aReply().iType)
+		{
+		case KDnsRequestType_GetByName:
+		case KDnsRequestType_GetByAddress:
+			{
+			TNameRecord &reply = aReply().NameRecord();
+			aReply.SetLength(aReply().HeaderSize() + sizeof(reply));
+			if (hdr.AA())
+				reply.iFlags |= EDnsAuthoritive;
+			ret = GetResponse(tempRR, reply);
+			reply.iFlags |= EDnsServer | (iIsFromCache ? EDnsCache : 0);
+			addr = &TInetAddr::Cast(reply.iAddr);
+			break;
+			}
+#ifndef NO_DNS_QUERY_SUPPORT
+		case KDnsRequestType_TDnsQuery:
+			ret = tempRR.GetResponse(aReply, &addr);
+			break;
+#endif
+		default:
+			return KErrNotSupported;
+		}
+	if (ret < 0)
+		return ret;		// Some error detected!
+
+	if (addr)
+		{
+		// Reply contains a TInetAddr. This needs some special processing
+
+		// Supplement IPv6 addresses with the scope value
+		// (Should do the same with IPv4 after converting to IPv4 mapped?)
+		if (addr->Family() == KAfInet)
+			addr->ConvertToV4Mapped();
+		if (addr->Family() == KAfInet6)
+			{
+			const TInt scope_level = addr->Ip6Address().Scope();
+
+			// Add the scope id only for addresses with larger than node
+			// local scope (this leaves the scope id as zero, if a loopback
+			// address is returned from the name server (The id of the node
+			// local scope is the interface index and non-zero value would
+			// bind loopback destination to real interface instead of internal
+			// loopback interface).
+			if (scope_level > KIp6AddrScopeNodeLocal)
+				addr->SetScope(iOwner->iServerManager.Scope(iRecord->Server(), *addr));
+
+#ifdef LLMNR_ENABLED
+			if(iOwner->iControl.GetConfig().iLlmnrLlOnly) // accept only linklocal replies to LLMNR queries
+				if (iFilter.iServerScope == EDnsServerScope_MC_LOCAL)
+					{
+					// Check compliance w. link-local addressing requirements (ipv6/ipv4)
+					if (scope_level != KIp6AddrScopeLinkLocal)
+						return KErrNotFound;
+					}
+#endif
+
+			//
+			// A backward compatibility hack: if address is IPv4 global address
+			// and the network scope in the query matches the scope of the address,
+			// then convert the returned address into old KAfInet format (and lose
+			// lose the scope id).
+			if (addr->IsV4Mapped() &&
+				addr->Scope() == aReply().iId &&
+				scope_level == KIp6AddrScopeNetwork)
+				addr->SetAddress(addr->Address());
+			}
+		}
+	return KErrNone;
+	}
+
+// TDndReqData::DoError
+// **********************
+/**
+// If a session has a DNS reply in cache associated with it, then
+// set the state of this reply to indicated error code.
+//
+// @param aError	the error code to be stored
+// @param aTLL		the new "Time To Live" for the record (in seconds). The
+//					record (and error state) will expire after this time.
+*/
+void TDndReqData::DoError(TInt aError, TUint aTTL)
+	{
+	if (aError >= 0)
+		return;		// Only errors can be set!
+
+	if (iRecord == NULL)
+		return;
+	iRecord->FillErrorCode(aError, aTTL);
+	}
+
+// TDndReqData::DoQueryL
+// ***********************
+/**
+// Activate a query of specified type for the loaded query information
+// (enable RecvReply callback). Note: the callback may occur already within call!
+//
+// @param	aRequestTime is the time when the request is received from the application
+// @param	aQType	type of the query (all queries assume IN class)
+// @returns
+//	@li	< 0, serious error, (resolving process should be aborted)
+//	@li	= 0, reply found from cache (reply callback has been called)
+//	@li	= 1, DNS Query message has been queued for transmission
+// @execption
+//	LEAVE on any serious error (resolving process should be aborted)
+*/
+TInt TDndReqData::DoQueryL(const TTime &aRequestTime, const EDnsQType aQType)
+	{
+	// -- class is now always IN,
+	// -- should only look from cache if aQType is not a "wildcard" type
+	//    (however, if wildcard, cache should not give hits...)
+	iQuestion.SetQType(aQType);
+	// -- only IN class queries are supported
+	iQuestion.SetQClass(EDnsQClass_IN);
+
+	if (iRecord)
+		{
+		iRecord->Unlock(this);
+		iRecord = NULL;
+		}
+
+	if (iCurrentServer == 0)
+		{
+		if (!PickDefaultServer())
+			{
+			SendResponse(KErrDndServerUnusable);
+			return 0;
+			}
+		if (iCurrentServer == 0)
+			{
+			// Cannot check cache nor start any query, if the
+			// name space id cannot be determined (no interfaces
+			// up). Return "query queued" anyway, and let the
+			// resolver retry process try it again later.
+			iIsReqPending = TRUE;
+			return 1;
+			}
+		}
+	TUint32 id = iOwner->iServerManager.NameSpace(iFilter, iCurrentServer);
+
+	if (id == 0)
+		{
+		SendResponse(KErrDndServerUnusable);
+		return 0;
+		}
+				
+	// Check in the cache first. If the record does not exist
+	// in the cache, it will be created now (empty with KErrNotFound).
+	iRecord = iOwner->iCache->FindL(
+			id,
+			iQuestion,
+			iQuestion.QType(),
+			// *HACK WARNING* To achieve independent caching of answers which
+			// are result of queries where RD=1 or RD=0 (recursion desired),
+			// the Class value is made different depending on the RD state.
+			(EDnsQClass)(iQuestion.QClass() | ((iFlags & KDnsModifier_RD) ? 0 : 0x80)),
+			aRequestTime);
+	// The above FindL must either leave of return a valid
+	// record pointer. Just as a safety measure, if record
+	// is not returned, then panic on in DEBUG builds, and
+	// in release, leave with KErrDndNoRecord
+	// (** however, this should never happen! **)
+	ASSERT(iRecord != NULL);
+	if (iRecord == NULL)
+		User::Leave(KErrDndNoRecord);
+
+	// Prevent record from being deleted while the
+	// iRecord pointer exists...
+	iRecord->Lock();
+	switch(iRecord->ErrorCode())
+		{
+		// If no error in the record, retrieve the informations and send
+		case KErrNone:	
+		// For certain errors, send the error code
+		case KErrDndBadName:
+		case KErrDndNotImplemented:
+		case KErrDndRefused:
+		case KErrDndNoRecord:
+			iIsFromCache = TRUE;
+			iIsNewQuery = FALSE;
+			if (IsQueued())
+				Cancel();
+			SendResponse(iRecord->ErrorCode());
+			return 0;
+		
+		// For other errors, try sending the query to the DNS
+		default:
+			break;
+		}
+
+	// Automatic restart of DNS socket, if closed for some reason
+	iOwner->ActivateSocketL(iNetworkId);  // pass on the networkId information
+
+	iIsReqPending = TRUE;
+	// If the query is probe, do not AssignWork but continue..
+	if (!(iFlags & KDnsModifier_PQ) && !iRecord->AssignWork(this))
+		return 1;	// just let the other worker do the job.
+
+	// Try to detect retransmissions of the same query and
+	// reuse old ID in such case... (don't generate a new)
+	if (iIsNewQuery ||
+		iQuestion.QType() != aQType ||
+		iQuestion.QClass() != EDnsQClass_IN)
+		Cancel();				// A new ID required
+
+	iIsNewQuery = FALSE;
+	iIsFromCache = FALSE;
+
+	// If the DNS "mode" is Multicast DNS, then assume that PTR queries
+	// which are generated from IP address are to be made via TCP. Test
+	// this and use TCP if query is PTR query for valid IP address.
+	// [specified in draft-ietf-dnsext-mdns-22.txt, but generalized here
+	// also for any future Multicast DNS]
+	for ( ;iFilter.IsMulticast() && iQuestion.QType() == EDnsQType_PTR;)
+		{
+		// Use "for" just for easy "break" exits!
+		TInetAddr server;
+
+		// Get correct DNS port number into 'server' (actual address is thrown away)
+		if (iOwner->iServerManager.Address(iCurrentServer, server) != KErrNone)
+			break;
+		// Use server address type as a flag, whether Ipv4 or IPv6 is done
+		const TInt is_ipv4 = server.IsV4Mapped();
+
+		if (!iQuestion.GetAddress(server) || !server.IsUnicast())
+			break;
+		// Usually LLMNR has both IPv4 and IPv6 multicast addresses as "servers".
+		// There is no point in doing PTR query for the same address twice, thus
+		// only do it once per matching "server" address (thus, if there is no
+		// IPv4 multicast "server", no IPv4 reverse queries are done either).
+		if (is_ipv4 != server.IsV4Mapped())
+			{
+			SendResponse(KErrDndServerUnusable);
+			return 0;
+			}
+
+		// Supplement 'server' address with a scope id based on current server
+		server.SetScope(iOwner->iServerManager.Scope(iCurrentServer, server));
+
+		// For link local multicast, use TTL = 1 (otherwise, system default is used)
+		const TInt ttl = iFilter.iServerScope == EDnsServerScope_MC_LOCAL ? 1 : -1;
+		if (iOwner->Queue(*this, server, -1, ttl) != KErrNone)
+			break;
+		iIsUsingTCP = 1;
+		SendResponse(KDnsNotify_USING_TCP);
+		return 1;
+		}
+	iOwner->ReSend(*this);		// (uses old ID, if request queued already)
+	return 1;
+	}
+
+// TDndReqData::UpdateCacheData
+// ******************************
+/**
+// @param aQuery	the session from which the reply is updated
+// @param aMsg		the reply from the DNS server
+// @param aAnswerOffset the start offset to the andwer secion in the reply
+// @param aErr		the status code of the reply
+// @returns
+//	@li	TRUE, if cache record updated
+//	@li	FALSE, if not updated (error code is "transient", concerns single query)
+*/
+TBool TDndReqData::UpdateCacheData(const TMsgBuf &aMsg, const TInt aAnswerOffset, const TInt aErr)
+	{
+	if (iRecord == NULL)
+		return FALSE;
+
+#ifdef _LOG
+	THostName name;
+	iQuestion.GetName(name);
+	Log::Printf(_L("\t\tDNS session [%u] -- Update cache: %S (offset=%d) aErr=%d"), (TInt)this, &name, aAnswerOffset, aErr);
+#endif
+	if (aErr == KErrDndDiscard)
+		return FALSE;
+
+	// If there is already have valid answer cached, decide whether the new
+	// answer is better and should replace the old?
+	const TInet6HeaderDNS &new_hdr = aMsg.Header();
+	if (iRecord->ErrorCode() == KErrNone && !new_hdr.AA())
+		{
+		// If new header is not authoritative, then it will replace the value
+		// only if old is non-authoritative and there is no error.
+		const TInet6HeaderDNS &old_hdr = iRecord->Header();
+		if (old_hdr.AA() || aErr != KErrNone)
+			return FALSE; // Not updated, keep previous valid value in cache.
+		}
+
+	TBool updated = FALSE;
+	if (aErr == KErrNone || aErr == KErrDndBadName || aErr == KErrDndNotImplemented || aErr == KErrDndNoRecord)
+		{
+		// Try to locate the SOA record from the authority section and
+		// use the minttl as the ttl of the negative caching.
+		TInt ttl;
+		TDndRR soa(aMsg);
+#ifdef SYMBIAN_DNS_PUNYCODE
+		soa.iIdnEnabled = (TBool) iIdnEnabled;
+#endif //SYMBIAN_DNS_PUNYCODE
+		TInt off = soa.LocateRR(aAnswerOffset, new_hdr.ANCOUNT()+new_hdr.NSCOUNT(), EDnsQType_SOA, EDnsQClass_IN, new_hdr.ANCOUNT());
+		if (off < 0)
+			{
+			ttl = iOwner->iControl.GetConfig().iMaxTime;
+			LOG(Log::Printf(_L("\t\tDNS session [%u] -- Update cache: no SOA, default ttl = %d"), (TInt)this, ttl));
+			}
+		else if ((off = aMsg.SkipName(soa.iRd)) > 0 &&
+				 (off = aMsg.SkipName(off)) > 0 &&
+				 off >= (TInt)soa.iRd &&
+				 off + 20 <= (TInt)(soa.iRd + soa.iRdLength))
+			{
+			ttl = BigEndian::Get32(aMsg.Ptr()+off+16);
+			LOG(Log::Printf(_L("\t\tDNS session [%u] -- Update cache: SOA minttl = %d"), (TInt)this, ttl));
+			}
+		else
+			{
+			ttl = 0;	// The reply is broken in some way, use ttl = 0
+			LOG(Log::Printf(_L("\t\tDNS session [%u] -- Update cache: SOA access failed"), (TInt)this));
+			}
+		iRecord->FillData(aMsg, aAnswerOffset, iCurrentServer, aErr, ttl);
+#ifdef SYMBIAN_DNS_PUNYCODE
+		
+		LOG(iRecord->Print(iOwner->iControl,(TBool)iIdnEnabled));
+#else
+		LOG(iRecord->Print(iOwner->iControl));
+#endif //SYMBIAN_DNS_PUNYCODE
+		updated = TRUE;
+		}
+	//
+	// Got some answer from a server, update the "good" server (unless error indicates "bad"
+	//
+	if (iFilter.IsUnicast() && aErr != KErrDndRefused && aErr != KErrDndServerUnusable)
+		{
+		TInetAddr addr;
+		if (iOwner->iServerManager.Address(iCurrentServer, addr) == KErrNone)
+			{
+#ifdef _LOG
+			// borrow the 'name' from earlier LOG section!
+			addr.OutputWithScope(name);
+			Log::Printf(_L("\t\tDNS session [%u] -- Update cache: preferred server = %S port=%d ns=%d"),
+				(TInt)this, &name, addr.Port(), iOwner->iServerManager.NameSpace(iFilter, iCurrentServer));
+#endif
+			iOwner->iCache->SetServerAddress(iOwner->iServerManager.NameSpace(iFilter, iCurrentServer), addr, KErrNone);
+			}
+		}
+
+	return updated;
+	}
+
+
+void CDndDnsclient::QueryBegin()
+	{
+	++iActivityCount;
+	}
+
+
+void CDndDnsclient::QueryEnd()
+	{
+	ASSERT(iActivityCount > 0);
+	if (--iActivityCount == 0)
+		DeactivateSocket();
+	}
+
+
+//
+// TDndReqData
+//
+
+// TDndReqData::TranslateRCODE
+// ***************************
+/**
+//
+// @param	aHdr	The fixed DNS reply header
+//
+// @returns
+//	@li	KErrNone, if reply is ok
+//	@li	KErrDndDiscard/KErrDndUnknown
+//		if reply does not match the query, has errors
+//		in the format or RCODE was unknown
+//	@li	KErrDndFormat, RCODE was EDnsRcode_FORMAT_ERROR
+//	@li	KErrDndServerFailure, RCODE was EDnsRcode_SERVER_FAILURE
+//	@li	KErrDndBadName, RCODE was EDnsRcode_NAME_ERROR
+//	@li	KErrDndNotImplemented, RCODE was EDnsRcode_NOT_IMPLEMENTED
+//	@li	KErrDndRefuced, RCODE was EDnsRcode_REFUSED
+//	@li	KErrDndServerUnusable, if empty reply is not authoritative
+*/
+TInt TDndReqData::TranslateRCODE(const TDndHeader &aHdr, TInt aRCode) const
+	{
+	switch (aRCode) 
+		{
+		case EDnsRcode_NOERROR:
+			break;
+		case EDnsRcode_FORMAT_ERROR:
+			return KErrDndFormat;
+		case EDnsRcode_SERVER_FAILURE:
+			return KErrDndServerFailure;
+		case EDnsRcode_NAME_ERROR:
+			return KErrDndBadName;
+		case EDnsRcode_NOT_IMPLEMENTED:
+			return KErrDndNotImplemented;
+		case EDnsRcode_REFUSED:
+			return KErrDndRefused;
+		default:
+			return KErrDndUnknown;
+		}	
+
+	if (iOpcode == EDnsOpcode_QUERY && aHdr.QDCOUNT() != iQdCount)
+		return KErrDndDiscard;
+	//
+	// A special heuristics: discard empty replies, if the selected server does
+	// not do recursion as requested, and if it is not authority on the queried
+	// name. => return a special "server unusable for this query" error
+	if (aHdr.ANCOUNT() == 0 && (iFlags & KDnsModifier_RD) != 0 && !aHdr.RA() && !aHdr.AA())
+		return KErrDndServerUnusable;
+	return KErrNone;
+	}
+
+// TDndReqData::CheckQuestion
+// **************************
+/**
+// @param	aOffset starting offset of the question section in the message
+// @param	aMsg the reply message from a DNS server
+//
+// @returns
+//	@li	> 0,
+//		if message checks ok, the value is the new offset pointing
+//		to the next section after the question.
+//	@li	= 0, reply does not match the question.
+//	@li < 0, bad DNS reply
+*/
+TInt TDndReqData::CheckQuestion(const TMsgBuf &aMsg, TInt &aRCode) const
+	{
+	if (!iIsReqPending)
+		return 0;	// Not for me.
+
+	TDndQuestion question;
+	const TInt offset = aMsg.VerifyMessage(aRCode, question);
+	if (offset < 0)
+		return offset;	// Invalid message format, just ignore.
+	const TDndHeader &hdr = aMsg.Header();
+
+	// Only ONE question supported, sematics of receiving a reply
+	// with more than one Question are hairy... [which answers
+	// relate to which question?] (and multiple questions are
+	// not supported by current servers anyway -- msa)
+	if (hdr.QDCOUNT() != 1)
+		return KErrDndUnknown;
+
+	// This is supposed to be a REPLY, if not, then "no match".
+	if (!hdr.QR())
+		return 0;
+	// Reply OPCODE match the query?
+	if (hdr.OPCODE() != iOpcode)
+		return KErrDndDiscard;
+
+	// Does the question match the query?
+	//
+	if (question.CheckQuestion(iQuestion) != KErrNone)
+		return 0;
+	return offset;
+	}
+
+
+// TDndReqData::GetResponse
+// ************************
+/**
+// Map the contents of single resource record into TNameRecord.
+//
+// @param	aRR	the resource from which the reply is extracted
+// @retval	aAnswer receives the extracted value
+// @returns
+//	@li	KErrNone, if extraction successful
+//	@li	KErrDndNameTooBig, if answer cannot be fit into aAnswer
+//	@li and other errors
+*/
+TInt TDndReqData::GetResponse(const TDndRR &aRR, TNameRecord &aAnswer) const
+	{
+	TInt err = aRR.GetResponse(aAnswer.iName, TInetAddr::Cast(aAnswer.iAddr));
+	if (err != KErrNone)
+		return err;
+	aAnswer.iFlags |= (aRR.iType == EDnsType_CNAME) ? (EDnsAlias | EDnsServer) : EDnsServer;
+	return KErrNone;
+	}
+
+
+// TDndReqData::SendResponce
+// *************************
+/**
+// @param	aErr is the status,
+//	@li	= 0, the request has completed successfully
+//	@li > 0, request being processed, just a progress noticification
+//	@li	< 0, the request has completed with an error
+*/
+void TDndReqData::SendResponse(TInt aErr)
+	{
+	if (aErr <= 0)
+		{
+		iIsReqPending = FALSE;	// Current request completed
+		Cancel();
+		}
+	if (iCallback)
+		iCallback->ReplyCallback(aErr);
+	}
+
+// TDndReqData::Build
+// ******************
+/**
+// @retval	aMsg
+//		contains the fully constructed message to be sent to the DNS server,
+//		if Build succeeds
+// @retval	aServer
+//		contains the server address for which the message should be sent
+// @param	aMaxMessage
+//		the size of the current receive buffer (if UDP, zero for TCP)
+//
+// @returns TRUE, successful Build, and error (< 0) otherwise
+*/
+TBool TDndReqData::Build(CDnsSocket &aSource, TMsgBuf &aMsg, TInetAddr &aServer, TInt aMaxMessage)
+	{
+	CDndDnsclient &dns = (CDndDnsclient &)aSource;
+
+	if (dns.iServerManager.Address(iCurrentServer, aServer) != KErrNone)
+		return 0;
+	ASSERT(aServer.Port() != 0);
+
+	aMsg.SetLength(sizeof(TDndHeader));
+	TDndHeader &hdr = (TDndHeader &)aMsg.Header();
+	if (aServer.IsMulticast())
+		{
+		ASSERT(iFilter.IsMulticast());
+		hdr.SetRD(0);
+		if (aServer.IsV4Mapped())
+			{
+			if(iQuestion.QType() == EDnsQType_AAAA)
+				{
+				SendResponse(KErrDndServerUnusable);
+				return 0;
+				}
+			}
+		else
+			{
+
+			if(iQuestion.QType() == EDnsQType_A)
+				{
+				SendResponse(KErrDndServerUnusable);
+				return 0;
+				}
+			}
+#ifdef LLMNR_ENABLED
+		dns.SetHoplimit(dns.iControl.GetConfig().iLlmnrHoplimit);
+#endif
+		}
+	else
+		{
+#ifdef LLMNR_ENABLED
+		dns.SetHoplimit(-1);
+#endif
+		hdr.SetRD(iFlags & KDnsModifier_RD);
+		}
+	hdr.SetQdCount(1);
+	if (iQuestion.Append(aMsg) < 0)
+		return 0;
+
+	// Assume EDNS0 enabled, if the current receive buffer
+	// is larger than KDnsMaxMessage (all smaller
+	// values are treated as "no EDNS0".
+	if (aMaxMessage > KDnsMaxMessage)
+		{
+		TDndRROut opt(aMsg);
+#ifdef SYMBIAN_DNS_PUNYCODE
+		opt.iIdnEnabled = (TBool) iIdnEnabled;
+#endif //SYMBIAN_DNS_PUNYCODE
+		opt.iType = (TUint16)EDnsQType_OPT;
+		opt.iClass = (TUint16)aMaxMessage;
+		opt.iTTL = 0;	// RCODE = 0, version = 0, Z = 0
+		if (opt.Append(KNullDesC8, 0) == KErrNone)
+			{
+			hdr.SetArCount(1);
+			opt.AppendRData();
+			}
+		}
+	return 1;
+	}
+
+
+void TDndReqData::Sent(CDnsSocket &aSource)
+	{
+	CDndDnsclient &dns = (CDndDnsclient &)aSource;
+
+	dns.iServerManager.CloseList(iFilter);
+
+	SendResponse(KDnsNotify_QUERY_SENT);
+	}
+
+
+TBool TDndReqData::Reply(CDnsSocket &aSource, const TMsgBuf &aBuf, const TInetAddr &aServer)
+	{
+	TInt rcode = 0;
+	const TInt offset = CheckQuestion(aBuf, rcode);
+	if (offset < 0)
+		return 1;	// Invalid message format, just ignore.
+	const TDndHeader &hdr = aBuf.Header();
+	TInt err = TranslateRCODE(hdr, rcode);
+
+	CDndDnsclient &dns = (CDndDnsclient &)aSource;
+	ASSERT(&dns == iOwner);
+	// If configuration requests that "Not found" replies from a server
+	// are not to be cached, but ignored, then substitue err with
+	// KErrDndServerUnusable (meaning that this server is not usable for
+	// this query) This error is not cached!
+	//
+	if (err == KErrDndBadName && dns.iControl.GetConfig().iSkipNotFound)
+		err = KErrDndServerUnusable;
+	else if (iIsUsingTCP == 0 && hdr.TC() != 0)
+		{
+		// The current query was not TCP and got truncated reply,
+		// restart query with TCP (if we get truncated reply with
+		// TCP, something is broken...)
+		//
+
+		// It is assumed that the aServer has the correct port
+		// already set (it should be the remote port of the original
+		// UDP query)
+		ASSERT(aServer.IsUnicast());	// Should always be true.
+		if (aServer.IsUnicast())
+			{
+			if (iOwner->Queue(*this, aServer, hdr.ID()) == KErrNone)
+				{
+				iIsUsingTCP = 1;
+				SendResponse(KDnsNotify_USING_TCP);
+				return 1;
+				}
+			}
+		// If cannot use the TCP, then just use the trunctated
+		// answer as is...
+		}
+	//
+	// UpdateCacheData updates data in cache only, if err is KErrNone, or
+	// updates error status for some specific err codes,
+	// otherwise, it does nothing.
+	TBool updated = UpdateCacheData(aBuf, offset, err);
+
+#ifdef DEBUG_CACHE
+	iCache->Dump(*iControl);
+#endif
+
+	if (updated)
+		{
+		// Cache modified! In addition to the original query,
+		// send the responce to every request that is waiting for
+		// the same reply... (iRecord pointers are same).
+		for (TUint i = 0; i < KDndNumRequests; ++i)
+			{
+			TDndReqData &rq = dns.iDndReqData[i];
+			if (rq.iIsReqPending && iRecord == rq.iRecord)
+				{
+				rq.Cancel();	// No need to send the query
+				rq.SendResponse(err);
+				}
+			}
+		return 1;
+		}
+
+	// Cache not updated, send to original query only.
+	SendResponse(err);
+	return 1;
+	}
+
+void TDndReqData::Abort(CDnsSocket &/*aSource*/, const TInt aReason)
+	{
+	SendResponse(aReason);
+	}