RAW socket prgmming

RAW socket prgmming

[neha agrawal]

[-- Attachment #1: Type: text/plain, Size: 1187 bytes --]

hello!

        i want to implement smtp protocol on the same
machine.i have a libpcap trace file..in which i have
captured mail traffic..(single session).and i want to
develop a program which can read this trace file..and
communicate with the smtp server...
    first packet is Sync packet in trace file..so i
want to send it to smtp server...and then i want my
progrem to handle the reply sent by server..(say it
sent Syn-Ack) anf then my prgm should reply
accordingly..
       for doing this i am using PF_PACKET , SOCK_RAW
and using sendto function...i am sending the
packet..im able to see it through tcpdump...but
theserver is not replying...why??i am wrking with
linux Redhat 9 kernel 2.4.20-8
     
       (...if u r familiar with flowreplay tool..i
want to do something similar ...but mine is single
session..so less complicated...)

    attching source code...

 do let me know..if i am on correct track...
                                          thnks
                                           Neha

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[-- Attachment #2: tcp1.c --]
[-- Type: application/octet-stream, Size: 3266 bytes --]

#include "tcp.h"
#include<sys/ioctl.h>
#include<net/if.h>
#define PROTO htons(ETH_P_ALL)

int main()
{
  //unsigned char packet[74];

  struct sockaddr_ll mysocket,to,from;
  int fromlen;
  struct tcphdr *tcp;
  int sockd, sd,on = 1;
  unsigned char rbuf[1500];
  int i,n;
  char errbuf[PCAP_ERRBUF_SIZE];
  pcap_t* descr;
  const u_char *packet;
  struct pcap_pkthdr hdr;     /* pcap.h */
  struct ether_header *eptr;  /* net/ethernet.h */
  u_char *ptr; /* printing out hardware header info */
  struct iphdr *ip;
  struct ifreq ifr;

  descr = pcap_open_offline("/root/s1.trace",errbuf);
    if(descr == NULL)
    {
        printf("pcap_open_offline(): %s\n",errbuf);
        exit(1);
    }
    packet = pcap_next(descr,&hdr);
    if(packet == NULL)
    {
        printf("Didn't grab packet\n");
        exit(1);
    }

   if((sockd = socket(PF_PACKET,SOCK_RAW,PROTO)) < 0)  
   {
     perror("socket");
     exit(1);
   }
 
  strncpy(ifr.ifr_name, "lo", sizeof(ifr.ifr_name));
  if (ioctl(sockd, SIOCGIFINDEX, &ifr) == -1)
   {
    fprintf(stderr, "SIOCGIFINDEX on %s failed: %s\n", "lo",strerror(errno));
    printf("my error\n");
    return 1;
   }
 

  memset(&mysocket,'\0',sizeof(mysocket));  
  mysocket.sll_family = AF_PACKET;
  mysocket.sll_protocol =htons(ETH_P_ALL); 
  mysocket.sll_ifindex  = ifr.ifr_ifindex;
    
  if (bind(sockd,(struct sockaddr *)&mysocket, sizeof(mysocket)) <0) 
    {
     perror("Bind");
     exit(1);
    }
    printf("Bind succecced \n");

  memset(&to , 0,sizeof(to));
  to.sll_family = AF_PACKET;
  to.sll_protocol =htons(ETH_P_ALL); 
  to.sll_ifindex  = ifr.ifr_ifindex;
  to.sll_halen = ETH_ALEN;
  memcpy(to.sll_addr,packet,ETH_ALEN);


 ip = (struct iphdr *) packet;  
 printf("Id1 %d\n",ip->ttl);
 ip->id=htons(getuid());
 printf("ID2 %d\n",(ip->id));
  n = sendto(sockd,packet,74,0x0,(struct sockaddr *)&to,sizeof(to));   
  if(n < 0)  
   {
    perror("sendto");
    exit(1);
    }
 else  printf("Packet send %d bytes \n",n);
  
  /* capture */
  printf("Now recev\n");
  
  
  bzero(rbuf,sizeof(rbuf));
  fromlen = sizeof(from);
  n = recvfrom(sockd,rbuf,sizeof(rbuf),0,(struct sockaddr *)&from,&fromlen);
 
   if(n < 0)  printf("ERROR\n");
    else printf("RECEived %dbytes\n",n);  
  
   printf("Packet type %d\n",from.sll_pkttype);
   printf("Packet hatype %d\n",from.sll_hatype);


    eptr = (struct ether_header *) rbuf;
    if (ntohs (eptr->ether_type) == ETHERTYPE_IP)
    {
        printf("Ethernet type hex:%x dec:%d is an IP packet\n",
                ntohs(eptr->ether_type),
                ntohs(eptr->ether_type));
    }
       else  if (ntohs (eptr->ether_type) == ETHERTYPE_ARP)
      {
        printf("Ethernet type hex:%x dec:%d is an ARP packet\n",
                ntohs(eptr->ether_type),
                ntohs(eptr->ether_type));
      }
      else 
       {
        printf("Ethernet type %x not IP", ntohs(eptr->ether_type));
        exit(1);
      }

   ip = (struct iphdr *)rbuf;
   printf("Version %d\n",ip->version);
   printf("Protocol %d\n",ip->protocol);
   //printf("Source IP: %s \t Destn IP: %s \n",inet_ntoa(ip->saddr) , inet_ntoa(ip->daddr));
   tcp  = (struct tcphdr *) rbuf;
   printf("Souce %04d and destn port %04d\n", ntohs(tcp->source), ntohs(tcp->dest));   
 
  exit(0);
}

[-- Attachment #3: tcp.h --]
[-- Type: application/octet-stream, Size: 385 bytes --]

#include <stdlib.h>
#include <stdio.h>
#include<pcap.h>
#include<errno.h>
//#include <libnd.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <netinet/in_systm.h>

#include <linux/ip.h>
#include <linux/tcp.h>
#include <netinet/if_ether.h>

#include<netpacket/packet.h>
#include <string.h>
#include <unistd.h>
#include <time.h>