tcpiputils/networkaddressandporttranslation/src/icmp.cpp
changeset 0 af10295192d8
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-1:000000000000 0:af10295192d8
       
     1 // Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
       
     2 // All rights reserved.
       
     3 // This component and the accompanying materials are made available
       
     4 // under the terms of "Eclipse Public License v1.0"
       
     5 // which accompanies this distribution, and is available
       
     6 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
       
     7 //
       
     8 // Initial Contributors:
       
     9 // Nokia Corporation - initial contribution.
       
    10 //
       
    11 // Contributors:
       
    12 //
       
    13 // Description:
       
    14 // napt.cpp
       
    15 // implementation of ICMP tranlation
       
    16 // 
       
    17 //
       
    18 
       
    19 /**
       
    20  @file
       
    21  @internalTechnology 
       
    22 */
       
    23 
       
    24 #include "hookdefs.h"
       
    25 #include <e32std.h>
       
    26 #include <in6_opt.h>
       
    27 #include <udp_hdr.h>
       
    28 #include <icmp6_hdr.h>
       
    29 #include <udp_hdr.h>
       
    30 #include <in_pkt.h>
       
    31 #include <ext_hdr.h>
       
    32 #include <in_chk.h>
       
    33 #include <tcp_hdr.h>
       
    34 #include <icmp6_hdr.h>
       
    35 #include "naptlog.h"
       
    36 #include "panic.h"
       
    37 #include "napt_ini.h"
       
    38 #include <posthook.h>
       
    39 
       
    40 
       
    41 /*
       
    42 *----------------------------------------------------------------------------------------
       
    43 *						ICMP FILE
       
    44 *  Every ICMP message is supported except ICMP Redirect message. NAPT will not temper
       
    45 *  Other messages are taken care.
       
    46 *------------------------------------------------------------------------------------------
       
    47 */
       
    48 
       
    49 
       
    50 TInt CProtocolNaptIn::IcmpHandler(RMBufHookPacket& aPacket, RMBufRecvInfo& aInfo)
       
    51 /* This Function will manipulate ICMP packets. It will handle two ICMP cases.
       
    52  * First ping request.
       
    53  * Second is Destination unreachable
       
    54  * @param aPacket
       
    55  * @param aInfo
       
    56 */
       
    57 	{
       
    58 	TUint lSrcPort;
       
    59     // This flag states that packets have been translated and that KIp6Hook_DONE should be used as return value
       
    60 	TBool translatedFlag = EFalse;
       
    61 
       
    62 	TInet6Checksum<TInet6HeaderIP4> lIp(aPacket);
       
    63 	TInt lengthIP	= lIp.iHdr->HeaderLength();
       
    64     
       
    65 	//Obtain ICMP packet for checking error type 
       
    66     TInet6Checksum<TInet6HeaderICMP_Echo> lIcmpIn(aPacket,lengthIP);
       
    67     TUint type = lIcmpIn.iHdr->Type();
       
    68 	
       
    69 	//query identifier for particular ICMP echo reply
       
    70     TUint16 queryId = lIcmpIn.iHdr->Identifier();
       
    71 	
       
    72 	const CNaptIPPortMap* table= NULL;
       
    73 	TNaptConfigInfo* info = NULL;
       
    74  
       
    75 	switch(type)
       
    76 		{
       
    77 			case KInet4ICMP_TimeStampReply:
       
    78 				LOG(Log::Printf(_L("ICMP type is time stamp reply ")));
       
    79 			case KInet4ICMP_EchoReply:
       
    80 						
       
    81 				LOG(Log::Printf(_L("ICMP type is PING response ")));
       
    82 
       
    83 				//check whether translation is required or not.Result should be KErrNone
       
    84 				table =iNapt->iNaptMapMgr.GetIPTranslationNode(queryId);
       
    85 
       
    86 		    	if (table)
       
    87 		    		{
       
    88 		    		lIcmpIn.iHdr->SetIdentifier(table->iSrcPort); //Store Original Query Id from node
       
    89 		    		info = table->iConfigInfo; //Store Config info in the local pointer
       
    90 		    	
       
    91 		    		//recompute checksum as we have changed query id
       
    92 		    		lIcmpIn.ComputeChecksum(aPacket,NULL);
       
    93 		    	    		
       
    94 		    	  	//Take original IP which is translated by NAPT.
       
    95 		 			TUint32 originalIP;
       
    96 			  		originalIP=table->iSrcIpAddr;
       
    97 			            
       
    98 		            //Set destination IP to the Original IP which was translated
       
    99 		            lIp.iHdr->SetDstAddr(originalIP);
       
   100 		            TInetAddr::Cast(aInfo.iDstAddr).SetV4MappedAddress(originalIP);
       
   101 
       
   102 					//This will set source scope i,e networkID as zero this will allow incoming hook to set scope 
       
   103 					//by itself.
       
   104 
       
   105 		            lIp.ComputeChecksum();
       
   106 		            translatedFlag = ETrue;
       
   107 		            
       
   108 		    		}
       
   109 		    	break;
       
   110 				
       
   111 			case KInet4ICMP_SourceQuench:
       
   112 
       
   113 		 	case KInet4ICMP_TimeExceeded:
       
   114 				//IcmpHandlerTracert return type is TBool, which is same as TInt, hence it the return value is 
       
   115 				//directly assigned to translatedFlag. Any change in return value (other than 0 and 1), 
       
   116 				//this assginment have to be revisited.
       
   117 		 	   translatedFlag =	IcmpHandlerTracert(aPacket, aInfo, &info);
       
   118 		 		break;
       
   119 
       
   120 				
       
   121 			case KInet4ICMP_ParameterProblem:
       
   122 			
       
   123 			case KInet4ICMP_Unreachable:
       
   124 				LOG(Log::Printf(_L("my type id is %d"),type));
       
   125 
       
   126 /*------------------------------------------------------------------------------------				
       
   127 *			 	ICMP destination Unreachable packet format.
       
   128 *				
       
   129 *					-------------------------------------------------
       
   130 *			        |	OUTER	|ICMP	|INNER	|UDP		|PAYLOAD|
       
   131 *				    |	IP		|HEADER	|IP     |           |       |
       
   132 *				    |	HEADER	|		|header |HEADER		|		|
       
   133 *					-------------------------------------------------
       
   134 *
       
   135 *  Rare case TYPE 3 CODE 4..NAPT not required 
       
   136 *
       
   137 *From RFC 1191 for use when the code is set to 4: 
       
   138 *when a router is unable to forward a datagram because it exceeds the MTU of the 
       
   139 *next-hop network and its Don't Fragment bit is set, the router is required to 
       
   140 *return an ICMP Destination Unreachable message to the source of the datagram,
       
   141 *with the Code indicating "fragmentation needed and DF set". 
       
   142 *To support the Path MTU Discovery technique specified in this memo, 
       
   143 *the router MUST include the MTU of that next-hop network in the low-order 16 bits of
       
   144 *the ICMP header field that is labelled "unused" in the ICMP specification.
       
   145 *The high-order 16 bits remain unused, and MUST be set to zero....
       
   146 *The size in bytes of the largest datagram that could be forwarded, 
       
   147 *along the path of the original datagram, without being fragmented at this
       
   148 *router. The size includes the IP header and IP data, and does not include 
       
   149 *any lower-level headers. This field will never contain a value less than 
       
   150 *68 since every router must be able to forward a 68 byte datagram without 
       
   151 *fragmentation.
       
   152 ---------------------------------------------------------------------------------------
       
   153 */
       
   154 	
       
   155 				//Split ICMP destnation Unreachable packet.
       
   156 				RMBufChain payload;
       
   157 				aPacket.SplitL(lengthIP, payload); 
       
   158 				
       
   159 				TInet6Checksum<TInet6HeaderICMP> lIcmpIn(payload);
       
   160 
       
   161 				TInt code = lIcmpIn.iHdr->Code();
       
   162 				TInt lenHeader=0;
       
   163      		    if(code==KInet4ICMP_CODE_DF)
       
   164      		    	{
       
   165      		    	//rare case TYPE 3, CODE 4 dont need NAPT.Since there is not Transport header
       
   166 			 		LOG(
       
   167 						TBuf<70> tmpSrc;
       
   168 						TBuf<70> tmpDst;
       
   169 						TInetAddr::Cast(aInfo.iSrcAddr).OutputWithScope(tmpSrc);
       
   170 						TInetAddr::Cast(aInfo.iDstAddr).OutputWithScope(tmpDst);
       
   171 						LOG(Log::Printf(_L("\t I am ICMP packet dont reqquire NAPT \n src=[%S] dst=[%S] ICMP code =%d"), &tmpSrc, &tmpDst,code,type));
       
   172 						);
       
   173 
       
   174      		    	aPacket.Append(payload);
       
   175      		    	return KIp6Hook_PASS;
       
   176      		    	}
       
   177      		    
       
   178      		    
       
   179      		    //Length of ICMP header + 4 is size of Empty + next Hop MTU
       
   180 				lenHeader= lIcmpIn.iHdr->HeaderLength() + 4 ;
       
   181 				
       
   182 				//Inner IP header
       
   183 				TInet6Checksum<TInet6HeaderIP4> lIpIn(payload, lenHeader);
       
   184 				lenHeader += lIpIn.iHdr->HeaderLength();
       
   185 			
       
   186 				//Find transport protocol it is using.According to this Translation will be made.
       
   187 				TInt transport;
       
   188 				transport=lIpIn.iHdr->Protocol();
       
   189 
       
   190 				LOG(Log::Printf(_L("I am using protocol=%d for communication and my destination is unreachable"),transport));
       
   191 				if(transport==KProtocolInetUdp)
       
   192 					{
       
   193 				
       
   194 					//Inner UDP header.
       
   195 					TInet6Packet<TInet6HeaderUDP> lUdpIn(payload,lenHeader);
       
   196 				
       
   197 					//check if header length is appropriate
       
   198 					if(lUdpIn.iHdr==NULL)
       
   199 						{
       
   200 						LOG(Log::Printf(_L("Insuffient header length")));
       
   201 						aPacket.Append(payload);
       
   202 						return KIp6Hook_PASS;
       
   203 						}
       
   204 					lenHeader += lUdpIn.iHdr->HeaderLength();
       
   205 					lSrcPort = lUdpIn.iHdr->SrcPort();
       
   206 		 
       
   207 		 			//Check if there is an entry in the translation table.
       
   208 					table = iNapt->iNaptMapMgr.GetIPTranslationNode(lSrcPort);
       
   209 					
       
   210 					
       
   211 					if(table)
       
   212 						{
       
   213 			    	  	TUint32 originalIP;
       
   214 			    	  	originalIP = table->iSrcIpAddr;
       
   215 			    	  	TUint originalPort = table->iSrcPort;
       
   216 			    	  	info = table->iConfigInfo;
       
   217 
       
   218 						lIp.iHdr->SetDstAddr(originalIP);
       
   219 		            
       
   220 		                //Translate inner IP information
       
   221 						lIpIn.iHdr->SetSrcAddr(originalIP);
       
   222 						lIpIn.ComputeChecksum();
       
   223 					
       
   224 						//Translate inner Port			
       
   225 						lUdpIn.iHdr->SetSrcPort(originalPort);
       
   226 					
       
   227 					
       
   228 						lUdpIn.iHdr->SetChecksum(0);
       
   229 			           
       
   230 			   			
       
   231 			            TInetAddr::Cast(aInfo.iDstAddr).SetV4MappedAddress(originalIP);
       
   232 						
       
   233 						//This will set source scope i,e networkID of private Interface this will allow incoming hook to set scope 
       
   234 						//by itself.
       
   235 						lIp.ComputeChecksum();
       
   236 		 	            translatedFlag = ETrue;
       
   237 
       
   238 						}
       
   239 				
       
   240 					aPacket.Append(payload);
       
   241 					//NULL argument id for ICMP v4 packets	
       
   242 					lIcmpIn.ComputeChecksum(aPacket,NULL,NULL);
       
   243 
       
   244 				    }//Protocol UDP if
       
   245 			
       
   246 				else if(transport==KProtocolInetTcp)
       
   247 					{
       
   248 					//Tcp Header
       
   249 					TInet6Checksum<TInet6HeaderTCP> lTcpIn(payload, lenHeader);
       
   250 					//check if header length is appropriate
       
   251 					if(lTcpIn.iHdr==NULL)
       
   252 						{
       
   253 						LOG(Log::Printf(_L("Insuffient header length rare case type 3 code 4")));
       
   254 						aPacket.Append(payload);
       
   255 						return KIp6Hook_PASS;
       
   256 						}
       
   257 
       
   258 					lenHeader += lTcpIn.iHdr->HeaderLength();
       
   259 					lSrcPort = lTcpIn.iHdr->SrcPort();
       
   260 
       
   261 					//check whether packet need translation...
       
   262 					table =iNapt->iNaptMapMgr.GetIPTranslationNode(lSrcPort);
       
   263 					
       
   264 					if(table)
       
   265 						{
       
   266 			    	  	TUint32 originalIP;
       
   267 			    	  	originalIP =table->iSrcIpAddr;
       
   268 			    	  	TUint originalPort = table->iSrcPort;
       
   269 			    	  	info = table->iConfigInfo;
       
   270 						
       
   271 						//outer IP header...
       
   272 						lIp.iHdr->SetDstAddr(originalIP);
       
   273 						
       
   274 						//Translate Inner IP header...
       
   275 						lIpIn.iHdr->SetSrcAddr(originalIP);
       
   276 						lIpIn.ComputeChecksum();
       
   277 										
       
   278 						//Translate Port....
       
   279 						lTcpIn.iHdr->SetSrcPort(originalPort);
       
   280 			   	
       
   281 			   	
       
   282 			   			//this one is to avoid armv5 errors and calculate checksum right
       
   283 						RMBufChain& payload = static_cast<RMBufChain&>(aPacket);	   	
       
   284 			   			lTcpIn.ComputeChecksum(payload,&aInfo,aInfo.iOffset);
       
   285 			
       
   286 			            TInetAddr::Cast(aInfo.iDstAddr).SetV4MappedAddress(originalIP);
       
   287 			
       
   288 
       
   289 						lIp.ComputeChecksum();
       
   290 			            translatedFlag = ETrue;
       
   291 
       
   292 		 				}
       
   293 					aPacket.Append(payload);
       
   294 					//NULL argument id for ICMP v4 packets
       
   295 				 	lIcmpIn.ComputeChecksum(aPacket,NULL,NULL);
       
   296 					}//Protocol TCP if
       
   297 				break;	
       
   298 	 		}//Switch end
       
   299 	if(translatedFlag)
       
   300 		{
       
   301 		aInfo.iFlags &= ~KIpAddressVerified;
       
   302 		LOG(
       
   303 			TBuf<70> tmpSrc;
       
   304 			TBuf<70> tmpDst;
       
   305 			TInetAddr::Cast(aInfo.iSrcAddr).OutputWithScope(tmpSrc);
       
   306 			TInetAddr::Cast(aInfo.iDstAddr).OutputWithScope(tmpDst);
       
   307 			LOG(Log::Printf(_L("\t I am translated ICMP packet \n src=[%S] dst=[%S] proto=%d"), &tmpSrc, &tmpDst, aInfo.iProtocol));
       
   308 			);
       
   309 
       
   310 	    // Setting the scope to 0 will cause the stack to automatically fill in the correct scope itself
       
   311 		TInetAddr::Cast(aInfo.iSrcAddr).SetScope(0);
       
   312 
       
   313 		//Setting Network ID of private Interfae as a scope. Route will be searched according 
       
   314 		//to the Destination Id which is set as the scope of private interface.
       
   315 		TInetAddr::Cast(aInfo.iDstAddr).SetScope(info->iScopeSrc);
       
   316 		
       
   317 		return KIp6Hook_DONE;	
       
   318 		}
       
   319 	
       
   320 	return KIp6Hook_PASS;
       
   321 
       
   322 	}
       
   323 	
       
   324 	
       
   325 void CProtocolNapt::IcmpHandlerForward(RMBufHookPacket& aPacket, RMBufRecvInfo& aInfo)
       
   326 /* This Function will manipulate ICMP packets. It will handle two ICMP cases.
       
   327  * First ping request.
       
   328  * @param aPacket
       
   329  * @param aInfo
       
   330 */
       
   331 	{
       
   332 		
       
   333     LOG(Log::Printf(_L(" CProtocolNapt::IcmpHandlerForwardL called for out going packets to global interface")));
       
   334 
       
   335 	//retrieve information from aInfo. This information will be maintained in the transation 
       
   336 	//table.
       
   337  	TUint32 sourceIP = (TInetAddr::Cast(aInfo.iSrcAddr)).Address();
       
   338     TUint32 destinationIP =(TInetAddr::Cast(aInfo.iDstAddr)).Address();
       
   339     const TUint32 targetIP= iCurConfigInfo->iPublicGatewayIP.Address();
       
   340 	
       
   341 	//IP packet.lengthIP is the length of IP header.
       
   342 	TInet6Checksum<TInet6HeaderIP4> lIp(aPacket);
       
   343 	TInt lengthIP	= lIp.iHdr->HeaderLength();
       
   344     
       
   345 	//Obtain ICMP packet. 
       
   346     TInet6Checksum<TInet6HeaderICMP_Echo> lIcmpIn(aPacket,lengthIP);
       
   347     TUint type = lIcmpIn.iHdr->Type();
       
   348     
       
   349 	//check if the type is ECHO i.e. 8. Then only translate else just pass packets.
       
   350     switch(type)
       
   351 	    {
       
   352 		
       
   353     case KInet4ICMP_TimeStamp:
       
   354     
       
   355 	case KInetICMP_Information_Request:
       
   356 	
       
   357 	case KInet4ICMP_AddressMask_Request:
       
   358 
       
   359 	case KInet4ICMP_DNS_Request:
       
   360 	    
       
   361     case KInet4ICMP_Echo :
       
   362 		LOG(Log::Printf(_L("my type id is %d"),type));
       
   363 
       
   364 	    TUint16 orgQueryId = lIcmpIn.iHdr->Identifier();
       
   365 
       
   366 		const CNaptIPPortMap* table=NULL;
       
   367 
       
   368 		//Finds  Translation Node,if already existing or creates  a new node filled with unique translated port number for 
       
   369 		//translated IP for TCP/UDP/ICMP connections.  
       
   370 		TRAPD(ret,table=iNaptMapMgr.FindOrCreateNaptEntryL(KProtocolInetIcmp ,sourceIP, destinationIP,orgQueryId ,0, iCurConfigInfo));
       
   371 	
       
   372 		if(table==NULL || (ret== KErrNoMemory))
       
   373 			{
       
   374 			LOG(Log::Printf(_L("No entry for table ")));
       
   375 			return;
       
   376 			}
       
   377 			
       
   378 		//set new Query Id -extract which is set in table node
       
   379 		lIcmpIn.iHdr->SetIdentifier(table->iTrPort)	;
       
   380 		//recompute checksum as we have changed QueryId in IcmpEchoRequest packet.
       
   381 		lIcmpIn.ComputeChecksum(aPacket, NULL);
       
   382 						
       
   383 		lIp.iHdr->SetSrcAddr(targetIP);
       
   384 	    TInetAddr::Cast(aInfo.iSrcAddr).SetV4MappedAddress(targetIP);
       
   385 
       
   386 	    // Setting the scope to 0 will cause the stack to automatically fill in the correct scope itself
       
   387 		TInetAddr::Cast(aInfo.iSrcAddr).SetScope(0);
       
   388 
       
   389 		//Setting Network ID of desired interface as a scope. Route will be searched according 
       
   390 		//to the Destination Id which is set as the scope of desired interface.
       
   391 		TInetAddr::Cast(aInfo.iDstAddr).SetScope(iCurConfigInfo->iScopedest);
       
   392 		LOG(
       
   393 			TBuf<70> tmpSrc;
       
   394 			TBuf<70> tmpDst;
       
   395 			TInetAddr::Cast(aInfo.iSrcAddr).OutputWithScope(tmpSrc);
       
   396 			TInetAddr::Cast(aInfo.iDstAddr).OutputWithScope(tmpDst);
       
   397 			LOG(Log::Printf(_L("\t I am translated ICMP packet OutBound \n src=[%S] dst=[%S] proto=%d"), &tmpSrc, &tmpDst, aInfo.iProtocol));
       
   398 			);
       
   399 
       
   400 		//Compute checksum
       
   401 		lIp.ComputeChecksum();
       
   402 		aInfo.iFlags &= ~KIpAddressVerified;
       
   403 		break;
       
   404         }
       
   405 	}
       
   406 
       
   407 
       
   408 TInt CProtocolNaptIn::IcmpHandlerTracert(RMBufHookPacket& aPacket, RMBufRecvInfo& aInfo, TNaptConfigInfo** aConfigInfo)
       
   409 /*
       
   410 ------------------------------------------------------------------------------------------------
       
   411 *				Packet format for ICMP type 11(Time exceeded message)
       
   412 *				
       
   413 *				 -------------------------------------------------------
       
   414 *				|IP 	|ICMP	 	|IP			| ICMP					|
       
   415 *				|Header	|Header	 	|Header		| Header				|
       
   416 *				|		|Type =11	|			| Type = 8(ping request)|
       
   417 *				 -------------------------------------------------------
       
   418 *	The internet header plus the first 8 bytes of the original datagram's data is returned to the sender. 
       
   419 *	This data is used by the host to match the message to the appropriate process.
       
   420 *	If a higher level protocol uses port numbers, they are assumed to be in the first 64 data bits of the original datagram's data.
       
   421 *
       
   422 *	Tracert could be a application.Clients can send UDP packets for tracert.64 bits(8bytes)might contain transport header.
       
   423 *	
       
   424 *
       
   425 *				 -------------------------------------------------------
       
   426 *				|IP 	|ICMP	 	|IP			| 	64 bits of data 	|
       
   427 *				|Header	|Header	 	|Header		| 	which could contain	|
       
   428 *				|		|Type =11	|			| 	port)				|
       
   429 *				 -------------------------------------------------------
       
   430 *
       
   431 *
       
   432 -------------------------------------------------------------------------------------------------
       
   433 */
       
   434 	{
       
   435 	//source port of the packet
       
   436 	TUint lSrcPort;
       
   437 	
       
   438 	const CNaptIPPortMap* table= NULL;
       
   439 	
       
   440 	//IP header,this header will be outer most header of the packet. Take header length 
       
   441 	//and split packet.
       
   442 	TInet6Checksum<TInet6HeaderIP4> lIp(aPacket);
       
   443 	TInt lengthIP	= lIp.iHdr->HeaderLength();
       
   444 	
       
   445     // This flag states that packets have been translated and that KIp6Hook_DONE should be used as return value
       
   446 	TBool translatedFlag= EFalse;
       
   447 
       
   448 	//Split packet and seperate outer IP and ICMP
       
   449 	RMBufChain payload;
       
   450 	aPacket.SplitL(lengthIP, payload); 
       
   451 
       
   452 
       
   453 	TInet6Checksum<TInet6HeaderICMP> lIcmpTem(payload);
       
   454 
       
   455 	//Length of ICMP header + 4 is size of Empty + next Hop MTU
       
   456 	TInt headerLen = lIcmpTem.iHdr->HeaderLength() + 4 ;
       
   457 
       
   458 	//Inner IP header
       
   459 	TInet6Checksum<TInet6HeaderIP4> lIpInternal(payload, headerLen);
       
   460 	headerLen += lIpInternal.iHdr->HeaderLength();
       
   461 	
       
   462 	//Find whether after inner header there is transport header
       
   463 	TInt transport= lIpInternal.iHdr->Protocol();
       
   464 	
       
   465 	if(transport==KProtocolInetUdp)
       
   466 		{
       
   467 		//Inner UDP header.
       
   468 		TInet6Packet<TInet6HeaderUDP> lUdpIn(payload,headerLen);
       
   469 
       
   470 		//check if header length is appropriate
       
   471 		if(lUdpIn.iHdr==NULL)
       
   472 			{
       
   473 			LOG(Log::Printf(_L("Insuffient header length")));
       
   474 			aPacket.Append(payload);
       
   475 			return KIp6Hook_PASS;
       
   476 			}
       
   477 		headerLen += lUdpIn.iHdr->HeaderLength();
       
   478 		lSrcPort = lUdpIn.iHdr->SrcPort();
       
   479 
       
   480 		//Check if there is an entry in the translation table.
       
   481 		table = iNapt->iNaptMapMgr.GetIPTranslationNode(lSrcPort);
       
   482 
       
   483 		if(table)
       
   484 			{
       
   485 			TUint32 originalIP;
       
   486 			originalIP = table->iSrcIpAddr;
       
   487 			TUint originalPort = table->iSrcPort;
       
   488 			*aConfigInfo = table->iConfigInfo;
       
   489 
       
   490 			lIp.iHdr->SetDstAddr(originalIP);
       
   491 
       
   492 			//Translate inner IP information
       
   493 			lIpInternal.iHdr->SetSrcAddr(originalIP);
       
   494 			lIpInternal.ComputeChecksum();
       
   495 
       
   496 			//Translate inner Port			
       
   497 			lUdpIn.iHdr->SetSrcPort(originalPort);
       
   498 
       
   499 
       
   500 			lUdpIn.iHdr->SetChecksum(0);
       
   501 
       
   502 			TInetAddr::Cast(aInfo.iDstAddr).SetV4MappedAddress(originalIP);
       
   503 
       
   504 			//This will set source scope i,e networkID of private Interface this will allow incoming hook to set scope 
       
   505 			//by itself.
       
   506 			lIp.ComputeChecksum();
       
   507 			translatedFlag = ETrue;
       
   508 			}
       
   509 		//Append splitted packet.Means join outer IP and ICMP.
       
   510 		aPacket.Append(payload);
       
   511 	
       
   512 		//NULL argument id for ICMP v4 packets	
       
   513 		lIcmpTem.ComputeChecksum(aPacket,NULL,NULL);
       
   514 
       
   515 		}//Protocol UDP if
       
   516 
       
   517 	else if(transport==KProtocolInetTcp)
       
   518 		{
       
   519 		//Tcp Header
       
   520 		TInet6Checksum<TInet6HeaderTCP> lTcpIn(payload, headerLen);
       
   521 		//check if header length is appropriate
       
   522 		if(lTcpIn.iHdr==NULL)
       
   523 			{
       
   524 			LOG(Log::Printf(_L("Insuffient header length")));
       
   525 			aPacket.Append(payload);
       
   526 			return KIp6Hook_PASS;
       
   527 			}
       
   528 
       
   529 		headerLen += lTcpIn.iHdr->HeaderLength();
       
   530 		lSrcPort = lTcpIn.iHdr->SrcPort();
       
   531 
       
   532 		//check whether packet need translation...
       
   533 		table =iNapt->iNaptMapMgr.GetIPTranslationNode(lSrcPort);
       
   534 
       
   535 		if(table)
       
   536 			{
       
   537 			TUint32 originalIP;
       
   538 			originalIP =table->iSrcIpAddr;
       
   539 			TUint originalPort = table->iSrcPort;
       
   540             *aConfigInfo = table->iConfigInfo;
       
   541 			//outer IP header...
       
   542 			lIp.iHdr->SetDstAddr(originalIP);
       
   543 
       
   544 			//Translate Inner IP header...
       
   545 			lIpInternal.iHdr->SetSrcAddr(originalIP);
       
   546 			lIpInternal.ComputeChecksum();
       
   547 						
       
   548 			//Translate Port....
       
   549 			lTcpIn.iHdr->SetSrcPort(originalPort);
       
   550 
       
   551 
       
   552 			//this one is to avoid armv5 errors and calculate checksum right
       
   553 			RMBufChain& payload = static_cast<RMBufChain&>(aPacket);	   	
       
   554 			lTcpIn.ComputeChecksum(payload,&aInfo,aInfo.iOffset);
       
   555 
       
   556 			TInetAddr::Cast(aInfo.iDstAddr).SetV4MappedAddress(originalIP);
       
   557 
       
   558 
       
   559 			lIp.ComputeChecksum();
       
   560 			translatedFlag = ETrue;
       
   561 
       
   562 			}
       
   563 		aPacket.Append(payload);//Append splitted packet.Means join outer IP and ICMP.
       
   564 		//NULL argument id for ICMP v4 packets
       
   565 		lIcmpTem.ComputeChecksum(aPacket,NULL,NULL);
       
   566 		}//Protocol TCP if
       
   567 	else
       
   568 		{
       
   569 		TInet6Checksum<TInet6HeaderICMP_Echo> lIcmpPingHeader(payload, headerLen);
       
   570 
       
   571 		TUint16 queryId = lIcmpPingHeader.iHdr->Identifier();
       
   572 
       
   573 		table =iNapt->iNaptMapMgr.GetIPTranslationNode(queryId);
       
   574 
       
   575 		if(table)
       
   576 			{
       
   577 			TUint32 originalIP;
       
   578 			originalIP =table->iSrcIpAddr;
       
   579             *aConfigInfo = table->iConfigInfo;
       
   580 			//outer IP header...
       
   581 			lIp.iHdr->SetDstAddr(originalIP);
       
   582 
       
   583 			//Translate Inner IP header...
       
   584 			lIpInternal.iHdr->SetSrcAddr(originalIP);
       
   585 			lIpInternal.ComputeChecksum();
       
   586 
       
   587 			lIp.ComputeChecksum();
       
   588 			translatedFlag = ETrue;
       
   589 
       
   590 			lIcmpPingHeader.ComputeChecksum(aPacket,NULL,NULL);
       
   591 			}
       
   592 		//Append splitted packet.Means join outer IP and ICMP.
       
   593 		aPacket.Append(payload);
       
   594 		lIcmpTem.ComputeChecksum(aPacket,NULL,NULL);
       
   595 
       
   596 	}//ICMP else
       
   597 	return translatedFlag;	
       
   598 
       
   599 }
       
   600 
       
   601 
       
   602 
       
   603 
       
   604 
       
   605 
       
   606 
       
   607 
       
   608 
       
   609 
       
   610 
       
   611