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Code not able to understand please help

Tarun Batra (72)
i have the following code from some website.i am not able to understand following things:-
1>why they have used so many in_addr and in6_addr.
2>Why they have used the in6_addr twice.
3>I am also not able to understand the format specifier used in sscanf.
4>Final problem why they have written so long code in case of tcp6 and udp6.
If someone can explain all the above problems i would be very thank full to him


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void net_dump()
{
	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN::net_dump");
    char buf[BUFFERSIZE*2];

    struct in_addr laddr, raddr;
    struct in6_addr laddr6, raddr6;
    struct in6_addr swapladdr6, swapraddr6;
    unsigned lport, rport, state, uid;//, txq, rxq, num;
    int n;
    FILE *fp,*p;
   /* char file1[200]="C:\\NEWTCP.txt";
    p=fopen(file1,"a+");
    if(p==NULL)
    {
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","cannot open %s",file1);
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","cannot open file error %s", strerror(errno));
  	  printf("cannot open %s",file1);
  	 //exit(0);
    }*/
    sprintf(buf, "/proc/%d/net/tcp", getpid());
  	fp = fopen(buf, "r");

    if(fp != 0)
    {
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN TCP MODE above fgets buffer is %s",buf);
        fgets(buf, BUFFERSIZE*2, fp);
        while(fgets(buf, BUFFERSIZE*2, fp))
        {
        	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN TCP MODE buffer is %s",buf);
            n = sscanf(buf, " %*d: %x:%x %x:%x %x %*x:%*x %*x:%*x %*x %d",
                       &laddr.s_addr, &lport, &raddr.s_addr, &rport,
                       &state, &uid);

            if(n == 6)
				net_list_add("TCP", &laddr, lport, &raddr, rport, state, uid, 0);
        }
        fclose(fp);
    }

    snprintf(buf, BUFFERSIZE, "/proc/%d/net/tcp6", getpid());
  	fp = fopen(buf, "r");
    if(fp != 0)
    {
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN TCP6 MODE above fgets buffer is %s",buf);
        fgets(buf, BUFFERSIZE*2, fp);
        while(fgets(buf, BUFFERSIZE*2, fp))
        {
        	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN TCP6 MODE buffer is %s",buf);
            n = sscanf(buf, " %*d: %08X%08X%08X%08X:%x %08X%08X%08X%08X:%x %x %*x:%*x %*x:%*x %*x %d",
                       &laddr6.in6_u.u6_addr32[0], &laddr6.in6_u.u6_addr32[1],
                       &laddr6.in6_u.u6_addr32[2], &laddr6.in6_u.u6_addr32[3],
                       &lport,
                       &raddr6.in6_u.u6_addr32[0], &raddr6.in6_u.u6_addr32[1],
                       &raddr6.in6_u.u6_addr32[2], &raddr6.in6_u.u6_addr32[3],
                       &rport, &state, &uid);

   			swapladdr6.in6_u.u6_addr8[0] = laddr6.in6_u.u6_addr8[3];
   			swapladdr6.in6_u.u6_addr8[1] = laddr6.in6_u.u6_addr8[2];
   			swapladdr6.in6_u.u6_addr8[2] = laddr6.in6_u.u6_addr8[1];
   			swapladdr6.in6_u.u6_addr8[3] = laddr6.in6_u.u6_addr8[0];

            swapladdr6.in6_u.u6_addr8[4] = laddr6.in6_u.u6_addr8[7];
   			swapladdr6.in6_u.u6_addr8[5] = laddr6.in6_u.u6_addr8[6];
   			swapladdr6.in6_u.u6_addr8[6] = laddr6.in6_u.u6_addr8[5];
   			swapladdr6.in6_u.u6_addr8[7] = laddr6.in6_u.u6_addr8[4];

   			swapladdr6.in6_u.u6_addr8[8] = laddr6.in6_u.u6_addr8[11];
   			swapladdr6.in6_u.u6_addr8[9] = laddr6.in6_u.u6_addr8[10];
   			swapladdr6.in6_u.u6_addr8[10] = laddr6.in6_u.u6_addr8[9];
   			swapladdr6.in6_u.u6_addr8[11] = laddr6.in6_u.u6_addr8[8];

   			swapladdr6.in6_u.u6_addr8[12] = laddr6.in6_u.u6_addr8[15];
   			swapladdr6.in6_u.u6_addr8[13] = laddr6.in6_u.u6_addr8[14];
   			swapladdr6.in6_u.u6_addr8[14] = laddr6.in6_u.u6_addr8[13];
   			swapladdr6.in6_u.u6_addr8[15] = laddr6.in6_u.u6_addr8[12];


   			swapraddr6.in6_u.u6_addr8[0] = raddr6.in6_u.u6_addr8[3];
   			swapraddr6.in6_u.u6_addr8[1] = raddr6.in6_u.u6_addr8[2];
   			swapraddr6.in6_u.u6_addr8[2] = raddr6.in6_u.u6_addr8[1];
   			swapraddr6.in6_u.u6_addr8[3] = raddr6.in6_u.u6_addr8[0];

   			swapraddr6.in6_u.u6_addr8[4] = raddr6.in6_u.u6_addr8[7];
   			swapraddr6.in6_u.u6_addr8[5] = raddr6.in6_u.u6_addr8[6];
   			swapraddr6.in6_u.u6_addr8[6] = raddr6.in6_u.u6_addr8[5];
   			swapraddr6.in6_u.u6_addr8[7] = raddr6.in6_u.u6_addr8[4];

   			swapraddr6.in6_u.u6_addr8[8] = raddr6.in6_u.u6_addr8[11];
   			swapraddr6.in6_u.u6_addr8[9] = raddr6.in6_u.u6_addr8[10];
   			swapraddr6.in6_u.u6_addr8[10] = raddr6.in6_u.u6_addr8[9];
   			swapraddr6.in6_u.u6_addr8[11] = raddr6.in6_u.u6_addr8[8];

   			swapraddr6.in6_u.u6_addr8[12] = raddr6.in6_u.u6_addr8[15];
   			swapraddr6.in6_u.u6_addr8[13] = raddr6.in6_u.u6_addr8[14];
   			swapraddr6.in6_u.u6_addr8[14] = raddr6.in6_u.u6_addr8[13];
   			swapraddr6.in6_u.u6_addr8[15] = raddr6.in6_u.u6_addr8[12];


            if(n == 12)
				net_list_add("TCP6", &swapladdr6, lport, &swapraddr6, rport, state, uid, 1);
        }
        fclose(fp);
    }

    snprintf(buf, BUFFERSIZE*2, "/proc/%d/net/udp", getpid());
    fp = fopen(buf, "r");

    if(fp != 0) {
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN UDP MODE above fgets buffer is %s",buf);
        fgets(buf, BUFFERSIZE*2, fp);
        while(fgets(buf, BUFFERSIZE*2, fp))
        {
        	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN UDP MODE buffer is %s",buf);
            n = sscanf(buf, " %*d: %x:%x %x:%x %x %*x:%*x %*x:%*x %*x %d",
                       &laddr.s_addr, &lport, &raddr.s_addr, &rport,
                       &state, &uid);
            if(n == 6)
  				net_list_add("UDP", &laddr, lport, &raddr, rport, state, uid, 0);
        }
        fclose(fp);
    }

    snprintf(buf, BUFFERSIZE*2, "/proc/%d/net/udp6", getpid());
  	fp = fopen(buf, "r");
    if(fp != 0)
    {
    	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN UDP6 MODE above fgets buffer is %s",buf);
        fgets(buf, BUFFERSIZE*2, fp);
        while(fgets(buf, BUFFERSIZE*2, fp))
        {
        	__android_log_print(ANDROID_LOG_INFO,"Tarun","IN UDP6 MODE buffer is %s",buf);
            n = sscanf(buf, " %*d: %08X%08X%08X%08X:%x %08X%08X%08X%08X:%x %x %*x:%*x %*x:%*x %*x %d",
                       &laddr6.in6_u.u6_addr32[0], &laddr6.in6_u.u6_addr32[1],
                       &laddr6.in6_u.u6_addr32[2], &laddr6.in6_u.u6_addr32[3],
                       &lport,
                       &raddr6.in6_u.u6_addr32[0], &raddr6.in6_u.u6_addr32[1],
                       &raddr6.in6_u.u6_addr32[2], &raddr6.in6_u.u6_addr32[3],
                       &rport, &state, &uid);

   			swapladdr6.in6_u.u6_addr8[0] = laddr6.in6_u.u6_addr8[3];
   			swapladdr6.in6_u.u6_addr8[1] = laddr6.in6_u.u6_addr8[2];
   			swapladdr6.in6_u.u6_addr8[2] = laddr6.in6_u.u6_addr8[1];
   			swapladdr6.in6_u.u6_addr8[3] = laddr6.in6_u.u6_addr8[0];

            swapladdr6.in6_u.u6_addr8[4] = laddr6.in6_u.u6_addr8[7];
   			swapladdr6.in6_u.u6_addr8[5] = laddr6.in6_u.u6_addr8[6];
   			swapladdr6.in6_u.u6_addr8[6] = laddr6.in6_u.u6_addr8[5];
   			swapladdr6.in6_u.u6_addr8[7] = laddr6.in6_u.u6_addr8[4];

   			swapladdr6.in6_u.u6_addr8[8] = laddr6.in6_u.u6_addr8[11];
   			swapladdr6.in6_u.u6_addr8[9] = laddr6.in6_u.u6_addr8[10];
   			swapladdr6.in6_u.u6_addr8[10] = laddr6.in6_u.u6_addr8[9];
   			swapladdr6.in6_u.u6_addr8[11] = laddr6.in6_u.u6_addr8[8];

   			swapladdr6.in6_u.u6_addr8[12] = laddr6.in6_u.u6_addr8[15];
   			swapladdr6.in6_u.u6_addr8[13] = laddr6.in6_u.u6_addr8[14];
   			swapladdr6.in6_u.u6_addr8[14] = laddr6.in6_u.u6_addr8[13];
   			swapladdr6.in6_u.u6_addr8[15] = laddr6.in6_u.u6_addr8[12];


   			swapraddr6.in6_u.u6_addr8[0] = raddr6.in6_u.u6_addr8[3];
   			swapraddr6.in6_u.u6_addr8[1] = raddr6.in6_u.u6_addr8[2];
   			swapraddr6.in6_u.u6_addr8[2] = raddr6.in6_u.u6_addr8[1];
   			swapraddr6.in6_u.u6_addr8[3] = raddr6.in6_u.u6_addr8[0];

   			swapraddr6.in6_u.u6_addr8[4] = raddr6.in6_u.u6_addr8[7];
   			swapraddr6.in6_u.u6_addr8[5] = raddr6.in6_u.u6_addr8[6];
   			swapraddr6.in6_u.u6_addr8[6] = raddr6.in6_u.u6_addr8[5];
   			swapraddr6.in6_u.u6_addr8[7] = raddr6.in6_u.u6_addr8[4];

   			swapraddr6.in6_u.u6_addr8[8] = raddr6.in6_u.u6_addr8[11];
   			swapraddr6.in6_u.u6_addr8[9] = raddr6.in6_u.u6_addr8[10];
   			swapraddr6.in6_u.u6_addr8[10] = raddr6.in6_u.u6_addr8[9];
   			swapraddr6.in6_u.u6_addr8[11] = raddr6.in6_u.u6_addr8[8];

   			swapraddr6.in6_u.u6_addr8[12] = raddr6.in6_u.u6_addr8[15];
   			swapraddr6.in6_u.u6_addr8[13] = raddr6.in6_u.u6_addr8[14];
   			swapraddr6.in6_u.u6_addr8[14] = raddr6.in6_u.u6_addr8[13];
   			swapraddr6.in6_u.u6_addr8[15] = raddr6.in6_u.u6_addr8[12];

   			if(n == 12)
				net_list_add("UDP6", &swapladdr6, lport, &swapraddr6, rport, state, uid, 1);
        }
        fclose(fp);
    }
__android_log_print(ANDROID_LOG_INFO,"Tarun","OUT::net_dump");
    return;
}
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