Create ICMP packets containing valid IP and UDP data

The encapsulated IP packed was missing source/destination addresses and
the UDP datagram had size 0.

src/ConnectionManager.cpp

@@ -55,10 +55,10 @@ class FakeroutePacket* ConnectionManager::getPacketFor(char* sourceAddress, char
 
   if (isTransitHop((*entry).getTtl()/3)) {
     spoofedPacket = new TimeToLiveExpiredFakeroutePacket(sourcePort, destinationPort,
-							 sourceIp, destinationAddress);
+							 sourceIp, destinationAddress, sourceAddress);
   } else {
     spoofedPacket = new DestHostUnreachableFakeroutePacket(sourcePort, destinationPort,
-							   sourceIp, destinationAddress);
+							   sourceIp, destinationAddress, sourceAddress);
   }
 
   (*entry).incrementTtl(routeCount * 3);

src/DestHostUnreachableFakeroutePacket.cpp

@@ -33,9 +33,10 @@
 DestHostUnreachableFakeroutePacket::DestHostUnreachableFakeroutePacket(u_int16_t localReceivedSourcePort,
 								       u_int16_t localReceivedDestinationPort,
 								       char* localSpoofedSourceAddress, 
-								       char* localSpoofedDestinationAddress) : 
+								       char* localSpoofedDestinationAddress,
+								       char* localReceivedSourceAddress) :
   FakeroutePacket(localReceivedSourcePort, localReceivedDestinationPort,
-		  localSpoofedSourceAddress, localSpoofedDestinationAddress)
+		  localSpoofedSourceAddress, localSpoofedDestinationAddress, localReceivedSourceAddress)
 {}
 
 u_int16_t DestHostUnreachableFakeroutePacket::getIcmpType(void) {

src/DestHostUnreachableFakeroutePacket.h

@@ -41,7 +41,7 @@ class DestHostUnreachableFakeroutePacket : public FakeroutePacket {
   
  public:
   DestHostUnreachableFakeroutePacket(u_int16_t receivedSourcePort, u_int16_t receivedDestinationPort,
-				     char* spoofedSourceAddress, char* spoofedDestinationAddress);
+				     char* spoofedSourceAddress, char* spoofedDestinationAddress, char* receivedSourceAddress);
 };
 
 #endif

src/FakeroutePacket.cpp

@@ -46,17 +46,21 @@
 FakeroutePacket::FakeroutePacket(u_int16_t localReceivedSourcePort,
 				 u_int16_t localReceivedDestinationPort,
 				 char* localSpoofedSourceAddress, 
-				 char* localSpoofedDestinationAddress) : 
+				 char* localSpoofedDestinationAddress,
+				 char* localReceivedSourceAddress) :
   ICMP_HDR_SIZE(sizeof(struct icmp)),
   IP_HDR_SIZE(sizeof(struct iphdr)),
   UDP_HDR_SIZE(sizeof(struct udphdr))
 {
   receivedSourcePort        = localReceivedSourcePort;
   receivedDestinationPort   = localReceivedDestinationPort;
+  receivedSourceAddress     = localReceivedSourceAddress;
   spoofedSourceAddress      = localSpoofedSourceAddress;
   spoofedDestinationAddress = localSpoofedDestinationAddress;
 }
 
+FakeroutePacket::~FakeroutePacket() {}
+
 void FakeroutePacket::sendOn(int fd) {
 
   int sockfd;
@@ -81,10 +85,10 @@ void FakeroutePacket::sendOn(int fd) {
   packetTo.sin_family      = AF_INET;
   packetTo.sin_addr.s_addr = inet_addr(spoofedDestinationAddress);
 
-  buildIpHeader(spoofedSourceAddress, spoofedDestinationAddress, (char*)packet);
-  buildIcmpHeader((char*)(packet + IP_HDR_SIZE), IPPROTO_UDP);
   buildUdpHeader((char*)(packet + IP_HDR_SIZE + ICMP_HDR_SIZE), 
 		 receivedSourcePort, receivedDestinationPort);
+  buildIcmpHeader((char*)(packet + IP_HDR_SIZE), IPPROTO_UDP);
+  buildIpHeader(spoofedSourceAddress, receivedSourceAddress, (char*)packet);
 
   if (sendto(sockfd, packet, sizeof(packet), 0x0, (struct sockaddr*)&packetTo, sizeof(packetTo)) < 0) {
     fprintf(stderr, "Packet Send Failed.");
@@ -99,22 +103,25 @@ void FakeroutePacket::buildUdpHeader(char* packet, u_int16_t sourcePort,
   
   udphdr->source = htons(sourcePort);
   udphdr->dest   = htons(destinationPort);
+  udphdr->len    = htons(UDP_BODY_SIZE);
 }
 
 void FakeroutePacket::buildIcmpHeader(char* packet, int protocol) {
   struct iphdr *fakeIpHdr;
   struct icmp  *icmpHeader = (struct icmp*)packet;
 
-  char fakePacket[IP_HDR_SIZE];
+  char fakePacket[IP_HDR_SIZE] = {0};
   fakeIpHdr           = (struct iphdr*)fakePacket;
   fakeIpHdr->ihl      = 5;
   fakeIpHdr->version  = 4;
   fakeIpHdr->protocol = protocol;
+  fakeIpHdr->saddr    = inet_addr(receivedSourceAddress);
+  fakeIpHdr->daddr    = inet_addr(spoofedDestinationAddress);
 
   icmpHeader->icmp_type  = getIcmpType();
   icmpHeader->icmp_code  = getIcmpCode();
   icmpHeader->icmp_ip    = *(struct ip*)fakePacket;
-  icmpHeader->icmp_cksum = (int)in_cksum((unsigned short*)icmpHeader, ICMP_HDR_SIZE);
+  icmpHeader->icmp_cksum = (unsigned short)in_cksum((unsigned short*)packet, ICMP_HDR_SIZE + 8);
 }
 
 void FakeroutePacket::buildIpHeader(char* source, char* destination, char* packet) {

src/FakeroutePacket.h

@@ -38,11 +38,13 @@ class FakeroutePacket {
   const int ICMP_HDR_SIZE;
   const int IP_HDR_SIZE;
   const int UDP_HDR_SIZE;
+  const int UDP_BODY_SIZE = 40;
 
   u_int16_t receivedSourcePort;
   u_int16_t receivedDestinationPort;
   char*     spoofedSourceAddress;
   char*     spoofedDestinationAddress;
+  char*     receivedSourceAddress;
 
   virtual void buildUdpHeader(char* packet, u_int16_t sourcePort, u_int16_t destinationPort);
   virtual void buildIcmpHeader(char* packet, int protocol);
@@ -54,7 +56,7 @@ class FakeroutePacket {
 
  public:
   FakeroutePacket(u_int16_t receivedSourcePort, u_int16_t receivedDestinationPort,
-		  char* spoofedSourceAddress, char* spoofedDestinationAddress);
+		  char* spoofedSourceAddress, char* spoofedDestinationAddress, char* receivedSourceAddress);
   virtual ~FakeroutePacket();
   virtual void sendOn(int fd);
 };

src/TimeToLiveExpiredFakeroutePacket.cpp

@@ -34,9 +34,10 @@
 TimeToLiveExpiredFakeroutePacket::TimeToLiveExpiredFakeroutePacket(u_int16_t localReceivedSourcePort,
 								   u_int16_t localReceivedDestinationPort,
 								   char* localSpoofedSourceAddress, 
-								   char* localSpoofedDestinationAddress) : 
+								   char* localSpoofedDestinationAddress,
+                   char* localReceivedSourceAddress) :
   FakeroutePacket(localReceivedSourcePort, localReceivedDestinationPort,
-		  localSpoofedSourceAddress, localSpoofedDestinationAddress)
+		  localSpoofedSourceAddress, localSpoofedDestinationAddress, localReceivedSourceAddress)
 {}
 
 u_int16_t TimeToLiveExpiredFakeroutePacket::getIcmpType(void) {

src/TimeToLiveExpiredFakeroutePacket.h

@@ -38,10 +38,12 @@ class TimeToLiveExpiredFakeroutePacket : public FakeroutePacket {
  protected:
   u_int16_t getIcmpType(void);
   u_int16_t getIcmpCode(void);
+  char* receivedSourceAddress;
   
  public:
   TimeToLiveExpiredFakeroutePacket(u_int16_t receivedSourcePort, u_int16_t receivedDestinationPort,
-				   char* spoofedSourceAddress, char* spoofedDestinationAddress);
+				   char* spoofedSourceAddress, char* spoofedDestinationAddress, char* receivedSourceAddress);
+
 };
 
 #endif