pcap - Traceroute and packet capture -

the following code required capture route taken packet moves local router destination router. should print intermediate routers , ip addresses. code given below. output doesn't list ip addresses. shows 1 router's ip. how can modify code shows intermediate ip addresses? please me out. thank you!

input format: ./a.out (destination ip) (port no) (max_ttl) (max_probe)

the output got this:

./a.out 68.71.216.176 80 10 2 

tracing 68.71.216.176 max_ttl 10 on port 80 2 probes

1>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  1>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  2>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  2>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  3>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  3>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  4>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  4>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  5>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  5>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  6>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  6>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  7>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit  7>192.168.1.1:80.....192.168.1.3:35410------------------->time-to-live exceeded: time-to-live exceeded on transit   #include<stdio.h> #include<string.h> #include<stdlib.h> #include<sys/socket.h> #include<netinet/in.h> #include<unistd.h> #include<errno.h> #include<netinet/ip.h> #include<pcap.h> #include<signal.h> #include<arpa/inet.h>  /*ip header*/  struct ip_hdr { unsigned char ip_v:4, ip_hl:4; unsigned char ip_tos; unsigned short int ip_len; unsigned short int ip_id; unsigned short int ip_off; unsigned char ip_ttl; unsigned char ip_p; unsigned short int ip_sum; struct in_addr ip_src, ip_dst; };  /*icmp header*/  struct icmp_hdr { unsigned char icmp_type; unsigned char icmp_code; unsigned short int icmp_chksum; int icmo_nouse; };  struct udp_hdr { unsigned short int udp_srcport; unsigned short int udp_destport; unsigned short int udp_len; unsigned short int udp_chksum; };  int sockfd1; char *buf = "s",dst[inet_addrstrlen],src[inet_addrstrlen]; int ttl,max_ttl,max_probe,pac; struct sockaddr_in servaddr;  pcap_t *handle; unsigned short int port_now; int initiate_pcapsession(); void send_packets(int); void parse(u_char *,const struct pcap_pkthdr *,const u_char *);  int main (int argc, char **argv) { int state; unsigned short int port; if (argc < 5) {     printf ("\n usage ./a.out <d-ip> <port> <maxttl> <maxprobe>\n");     return 0; } port = atoi (argv[2]); max_ttl = atoi (argv[3]); max_probe = atoi (argv[4]);  printf ("tracing %s max_ttl %d on port %u  %d probes\n", argv[1], max_ttl, port, max_probe); servaddr.sin_family = af_inet;  if (inet_pton (af_inet, argv[1], &servaddr.sin_addr) < 0)     {         perror ("\tspecified address invalid:progrm terminates:inet_pton");         return 0;     }  if ((sockfd1 = socket (af_inet, sock_dgram, ipproto_udp)) < 0)     {         perror ("error creating socket:socket");         return 0;     }  if((state=initiate_pcapsession())==-1) {     printf("\ncoudnt create packet capture session:terminating");     return 0; }  (ttl = 1; ttl <= max_ttl; ttl++)     {      port_now=htons(port + ttl -1);         //printf("\n%d>",ttl);         servaddr.sin_port = port_now;         send_packets (ttl);     }  pcap_close(handle); close (sockfd1); return 0; }  int initiate_pcapsession() { int state; char *dev; char errbuf[pcap_errbuf_size]; struct bpf_program fp; char filter_exp[]="icmp , (icmp[0] = 11 , icmp[1] = 0) or (icmp[0] = 3 , icmp[1] = 3)"; bpf_u_int32 mask,net;  if((dev=pcap_lookupdev(errbuf))==null) {     printf("\ncoudnt find  default device: %s\n",errbuf);     return -1; } //  else //      printf("\nfound default device %s ",dev);  if (pcap_lookupnet ("wlan0", &net, &mask, errbuf) == -1) {     printf ("\ncoudn't netmask device %s:%s\n", "wlan0", errbuf);         return -1; }  if ((handle = pcap_open_live ("wlan0", bufsiz, 1, 270000, errbuf)) == null)     {         printf ("\ncoudn't open device %s:%s","wlan0", errbuf);         return -1;     }  if((state=pcap_setnonblock(handle, 1, errbuf))==-1) {     printf("\ncoudn't set capture descriptor non-blocking mode :%s",errbuf);     return -1; }  if (pcap_compile (handle, &fp, filter_exp, 0, net) == -1)     {         printf ("\ncoudn't parse filter %s:%s", filter_exp, pcap_geterr (handle));         return -1;     }  if (pcap_setfilter (handle, &fp) == -1)     {         printf ("\ncoudn't install filter %s:%s\n", filter_exp, pcap_geterr (handle));         return -1;     }  return 1; }  void send_packets( int ttl_now) { pid_t pid; int p,num,status; setsockopt (sockfd1, ipproto_ip, ip_ttl, &ttl_now, sizeof (ttl_now));  for(p=1;p<=max_probe;p++) {         if ((sendto(sockfd1, buf, sizeof (buf), 0, (struct sockaddr *) &servaddr,sizeof (servaddr))) == -1)             {                 perror ("sendto");             }             else             {             pac+=1;                     //printf("\n\t\tsent packet %d",pac);                     if((pid=fork())<0)                     {                         perror("fork");                             exit(0);                     }                     if(pid==0)                     {                             num=pcap_loop(handle,-1,parse,null);                             if(num)                  printf("\npcap_dispatch:%d packets captured",num);                             else                     printf("\npcap_dispatch:no pcakets captured");                     }                     else                     {                             sleep(1);                             //wait(&status);                             kill(pid,sigstop);                     }     } } }  void parse(u_char *args,const struct pcap_pkthdr *header,const u_char *packet) { struct ip_hdr *ip1 = (struct ip_hdr *) (packet + 14);   /*initialising ip pointer beyond sll protocol header 16 bytes */ struct icmp_hdr *icmp = (struct icmp_hdr *) (packet + 14 + sizeof (struct ip_hdr)); struct ip_hdr *ip2 = (struct ip_hdr *) (packet + 14 + sizeof (struct ip_hdr) + sizeof (struct icmp_hdr)); struct udp_hdr *udp = (struct udp_hdr *) (packet + 14 + sizeof (struct ip_hdr) + sizeof (struct icmp_hdr) + sizeof (struct ip_hdr));      //if (ntohs (udp->udp_destport) == ntohs (port_now))     //{     inet_ntop (af_inet, &ip1->ip_dst, dst, 16);     inet_ntop (af_inet, &ip1->ip_src, src, 16);     printf ("\n\t%d>%s:%u.....%s:%u------------------->",ttl, src,ntohs (udp->udp_destport), dst,ntohs (udp->udp_srcport));  if(icmp->icmp_code==0)         printf("time-to-live exceeded: time-to-live exceeded on transit\n"); else if(icmp->icmp_code==3)         printf("destination unreachable: port unreachable\n"); //}  exit(0); } 

this type of icmp packet has 2 ip headers. address you're looking not in ip1 (which you're printing), it's in ip2 (which did load, did not print values it).