// tcp_test [c]
int tcp_test(const char* ip_str, const short port)
{
    int sock, i;
    struct sockaddr_in s_in;
    int packetsize = 1024;
    unsigned char packet[packetsize];
    struct timeval tv, tv2, tv3;
    int caplen = 0;
    int times[REQUESTS];
    int min, avg, max, len;
    struct net_hdr nh;

    tv3.tv_sec=0;
    tv3.tv_usec=1;

    s_in.sin_family = PF_INET;
    s_in.sin_port = htons(port);
    if (!inet_aton(ip_str, &s_in.sin_addr))
            return -1;

    if ((sock = socket(s_in.sin_family, SOCK_STREAM, IPPROTO_TCP)) == -1)
            return -1;

    /* avoid blocking on reading the socket */
    if( fcntl( sock, F_SETFL, O_NONBLOCK ) < 0 )
    {
        perror( "fcntl(O_NONBLOCK) failed" );
        return( 1 );
    }

    gettimeofday( &tv, NULL );

    while (1)  //waiting for relayed packet
    {
        if (connect(sock, (struct sockaddr*) &s_in, sizeof(s_in)) == -1)
        {
            if(errno != EINPROGRESS && errno != EALREADY)
            {
                perror("connect");
                close(sock);

                printf("Failed to connect\n");

                return -1;
            }
        }
        else
        {
            gettimeofday( &tv2, NULL );
            break;
        }

        gettimeofday( &tv2, NULL );
        //wait 3000ms for a successful connect
        if (((tv2.tv_sec*1000000 - tv.tv_sec*1000000) + (tv2.tv_usec - tv.tv_usec)) > (3000*1000))
        {
            printf("Connection timed out\n");
            close(sock);
            return(-1);
        }
        usleep(10);
    }

    PCT; printf("TCP connection successful\n");

    //trying to identify airserv-ng
    memset(&nh, 0, sizeof(nh));
//     command: GET_CHAN
    nh.nh_type	= 2;
    nh.nh_len	= htonl(0);

    if (send(sock, &nh, sizeof(nh), 0) != sizeof(nh))
    {
        perror("send");
        return -1;
    }

    gettimeofday( &tv, NULL );
    i=0;

    while (1)  //waiting for GET_CHAN answer
    {
        caplen = read(sock, &nh, sizeof(nh));

        if(caplen == -1)
        {
            if( errno != EAGAIN )
            {
                perror("read");
                return -1;
            }
        }

        if( (unsigned)caplen == sizeof(nh))
        {
            len = ntohl(nh.nh_len);
            if( nh.nh_type == 1 && i==0 )
            {
                i=1;
                caplen = read(sock, packet, len);
                if(caplen == len)
                {
                    i=2;
                    break;
                }
                else
                {
                    i=0;
                }
            }
            else
            {
                caplen = read(sock, packet, len);
            }
        }

        gettimeofday( &tv2, NULL );
        //wait 1000ms for an answer
        if (((tv2.tv_sec*1000000 - tv.tv_sec*1000000) + (tv2.tv_usec - tv.tv_usec)) > (1000*1000))
        {
            break;
        }
        if(caplen == -1)
            usleep(10);
    }

    if(i==2)
    {
        PCT; printf("airserv-ng found\n");
    }
    else
    {
        PCT; printf("airserv-ng NOT found\n");
    }

    close(sock);

    for(i=0; i<REQUESTS; i++)
    {
        if ((sock = socket(s_in.sin_family, SOCK_STREAM, IPPROTO_TCP)) == -1)
                return -1;

        /* avoid blocking on reading the socket */
        if( fcntl( sock, F_SETFL, O_NONBLOCK ) < 0 )
        {
            perror( "fcntl(O_NONBLOCK) failed" );
            return( 1 );
        }

        usleep(1000);

        gettimeofday( &tv, NULL );

        while (1)  //waiting for relayed packet
        {
            if (connect(sock, (struct sockaddr*) &s_in, sizeof(s_in)) == -1)
            {
                if(errno != EINPROGRESS && errno != EALREADY)
                {
                    perror("connect");
                    close(sock);

                    printf("Failed to connect\n");

                    return -1;
                }
            }
            else
            {
                gettimeofday( &tv2, NULL );
                break;
            }

            gettimeofday( &tv2, NULL );
            //wait 1000ms for a successful connect
            if (((tv2.tv_sec*1000000 - tv.tv_sec*1000000) + (tv2.tv_usec - tv.tv_usec)) > (1000*1000))
            {
                break;
            }
            //simple "high-precision" usleep
            select(1, NULL, NULL, NULL, &tv3);
        }
        times[i] = ((tv2.tv_sec*1000000 - tv.tv_sec*1000000) + (tv2.tv_usec - tv.tv_usec));
        printf( "\r%d/%d\r", i, REQUESTS);
        fflush(stdout);
        close(sock);
    }

    min = INT_MAX;
    avg = 0;
    max = 0;

    for(i=0; i<REQUESTS; i++)
    {
        if(times[i] < min) min = times[i];
        if(times[i] > max) max = times[i];
        avg += times[i];
    }
    avg /= REQUESTS;

    PCT; printf("ping %s:%d (min/avg/max): %.3fms/%.3fms/%.3fms\n", ip_str, port, min/1000.0, avg/1000.0, max/1000.0);

    return 0;
}