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It is a program to get the source and destination address from the network adapter .When trying to compile the following program,I am been left with errors. Does Any one have an idea on these errors.Thanks

 #include <stdio.h>
    #include <conio.h>
    #include "packet32.h"
    #include <ntddndis.h>
     #include <stdint.h> 
    #include <cstdint>
    #define PCAP_DONT_INCLUDE_PCAP_BPF_H
    #include<pcap.h>

    #define SIZE_ETHERNET 14
    #define ETHER_ADDR_LEN  6
    #define PCAP_ERRBUF_SIZE 30

    /* Ethernet header */
        struct sniff_ethernet {
            u_char ether_dhost[ETHER_ADDR_LEN]; /* Destination host address */
            u_char ether_shost[ETHER_ADDR_LEN]; /* Source host address */
            u_short ether_type; /* IP? ARP? RARP? etc */
        };
        struct bpf_program {
        u_int bf_len;
        struct bpf_insn *bf_insns;
    };

        /* IP header */
        struct sniff_ip {
            u_char ip_vhl;      /* version << 4 | header length >> 2 */
            u_char ip_tos;      /* type of service */
            u_short ip_len;     /* total length */
            u_short ip_id;      /* identification */
            u_short ip_off;     /* fragment offset field */
        #define IP_RF 0x8000        /* reserved fragment flag */
        #define IP_DF 0x4000        /* dont fragment flag */
        #define IP_MF 0x2000        /* more fragments flag */
        #define IP_OFFMASK 0x1fff   /* mask for fragmenting bits */
            u_char ip_ttl;      /* time to live */
            u_char ip_p;        /* protocol */
            u_short ip_sum;     /* checksum */
            struct in_addr ip_src;
            struct in_addr ip_dst; /* source and dest address */
        };
        #define IP_HL(ip)       (((ip)->ip_vhl) & 0x0f)
        #define IP_V(ip)        (((ip)->ip_vhl) >> 4)

        /* TCP header */

        typedef __int32 int32_t;
    typedef unsigned __int32 u_int32_t;
        struct sniff_tcp {
            u_short th_sport;   /* source port */
            u_short th_dport;   /* destination port */
            u_int32_t th_seq;       /* sequence number */
            u_int32_t th_ack;       /* acknowledgement number */

            u_char th_offx2;    /* data offset, rsvd */
        #define TH_OFF(th)  (((th)->th_offx2 & 0xf0) >> 4)
            u_char th_flags;
        #define TH_FIN 0x01
        #define TH_SYN 0x02
        #define TH_RST 0x04
        #define TH_PUSH 0x08
        #define TH_ACK 0x10
        #define TH_URG 0x20
        #define TH_ECE 0x40
        #define TH_CWR 0x80
        #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
            u_short th_win;     /* window */
            u_short th_sum;     /* checksum */
            u_short th_urp;     /* urgent pointer */
    };

    int main(int argc, char *argv[])
    {

        //get file
         char *filename = argv[1];

         //error buffer
         char errbuff[PCAP_ERRBUF_SIZE];

         //open file and create pcap handler
         pcap_t * handler = pcap_open_offline(filename, errbuff);

         //The header that pcap gives us
        struct pcap_pkthdr *header;

        //The actual packet 
        const u_char *packet;   

          int packetCount = 0;
          int i;

          //write to file 
          FILE *fp = fopen ( "result.txt", "w" ) ;

          //tcp info
        const struct sniff_ethernet *ethernet; /* The ethernet header */
        const struct sniff_ip *ip; /* The IP header */
        const struct sniff_tcp *tcp; /* The TCP header */
        u_int size_ip;
        u_int size_tcp;

        while (pcap_next_ex(handler, &header, &packet) >= 0)
        {
            // Show the packet number
            printf("Packet # %i\n", ++packetCount);
            fprintf(fp,"Packet # %i\n", packetCount);

            // Show the size in bytes of the packet
            printf("Packet size: %d bytes\n", header->len);
            fprintf(fp,"Packet size: %d bytes\n", header->len);

            // Show a warning if the length captured is different
            if (header->len != header->caplen)
                printf("Warning! Capture size different than packet size: %ld bytes\n", header->len);

            // Show Epoch Time
            printf("Epoch Time: %d:%d seconds\n", header->ts.tv_sec, header->ts.tv_usec);
            fprintf(fp,"Epoch Time: %d:%d seconds\n", header->ts.tv_sec, header->ts.tv_usec);

            ethernet = (struct sniff_ethernet*)(packet);
            ip = (struct sniff_ip*)(packet + SIZE_ETHERNET);
            size_ip = IP_HL(ip)*4;
            if (size_ip < 20) {
                printf("   * Invalid IP header length: %u bytes\n", size_ip);
                return;
            }
            tcp = (struct sniff_tcp*)(packet + SIZE_ETHERNET + size_ip);

            printf("src port: %d dest port: %d \n", tcp->th_sport, tcp->th_dport);
            fprintf(fp,"src port: %d dest port: %d \n", tcp->th_sport, tcp->th_dport);

            printf("src address: %s dest address: %s \n",  inet_ntoa(ip->ip_src),  inet_ntoa(ip->ip_dst));
            fprintf(fp,"src address: %s dest address: %s \n",  inet_ntoa(ip->ip_src),  inet_ntoa(ip->ip_dst));

            printf("seq number: %u ack number: %u \n", (unsigned int)tcp-> th_seq, (unsigned int)tcp->th_ack);
            fprintf(fp,"seq number: %u ack number: %u \n", (unsigned int)tcp-> th_seq, (unsigned int)tcp->th_ack);

            // Add two lines between packets
            printf("\n");
            fprintf(fp,"\n");
        }
        fclose (fp);
         return(0);
    }

Following are the resulted errors

1>------ Build started: Project: qqq, Configuration: Release Win32 ------
1>Build started 6/1/2015 5:27:54 PM.
1>InitializeBuildStatus:
1>  Touching "Release\qqq.unsuccessfulbuild".
1>ClCompile:
1>  test1.c
1>test1.c(12): warning C4005: 'PCAP_ERRBUF_SIZE' : macro redefinition
1>          C:\Users\Sathwik\Desktop\AirCap\developers\WinPcap_Devpack\Include\pcap/pcap.h(76) : see previous definition of 'PCAP_ERRBUF_SIZE'
1>test1.c(20): error C2011: 'bpf_program' : 'struct' type redefinition
1>          C:\Users\Sathwik\Desktop\AirCap\developers\WinPcap_Devpack\Include\packet32.h(109) : see declaration of 'bpf_program'
1>test1.c(126): error C2561: 'main' : function must return a value
1>          test1.c(72) : see declaration of 'main'
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.34
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
sai
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    The errors are pretty self explanatory. They happen because you are defining things in _your_ code that are _already_ defined by the headers you are including. Don't do that. – Captain Obvlious Jun 01 '15 at 21:30
  • Could you tell us which parts about the errors you don't understand? Do you understand the words 'function', 'must', 'return', 'a', 'value'? Do they all fit together in your mind? If not, which ones don't fit? – autistic Jun 01 '15 at 22:24

1 Answers1

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There are a couple of problems with your code.

  1. Do not include "packet32.h" unless you're using one of the packet.dll routines. You are only using WinPcap routines, so you do not need to include "packet32.h", and removing it will get rid of the "'PCAP_ERRBUF_SIZE' : macro redefinition" warning and the "'bpf_program' : 'struct' type redefinition" error. (You should not use packet.dll routines if you don't need to, and, in your program, you don't need to.) You also don't need to include "".

    Also, do NOT define PCAP_DONT_INCLUDE_PCAP_BPF_H! That's a hack I added to libpcap for use ONLY when compiling some code internal to libpcap; users should NEVER define it.

  2. "'main' : function must return a value" means that the function named main() must return a value; i.e., the function must return a value in all the places where it returns, including in the code

        size_ip = IP_HL(ip)*4;
    if (size_ip < 20) {
        printf("   * Invalid IP header length: %u bytes\n", size_ip);
        return;
    }

    so you must say return(1); or something such as that, not just return;.