[En-Nut-Discussion] Implementing TCP disconnect timeouts

[Greg Wood]

Hello everyone,

I am still poking around with my ethernut board to get an handle on the
fundamentals I'll need when I get started on a real project.  I have
been trying to implement a mechanism to disconnect a TCP socket when
there is a timeout.  I have implemented a simple timer management system
driven by TIMER2 overflow, this works quite well in its limited
capabilities.  The trouble I am having is that the timeout will occur
correctly if the client (I'm using the Hercules setup utility to send
some raw bytes by TCP) is already disconnected.  If I leave the client
connected my code will not exit and disconnect the port.  My timer does
operate correctly (I can see a port bit change state when expires) and
as soon as I disconnect (assuming the timer has already expired) the
client my coded exits and disconnects the port.  I have tried a number
of different things but nothing seems to work properly.  Basically I
think the problem is that the fread function blocks until new data
arrives or the client disconnects.  My Code is below.  The TCP thread is
created, opens the file/port and calls Dump_TCP.  When Dump_TCP returns
the port and file is closed.  

How could I implement the functionality I am after?  What I am thinking
in the future is a timeout for a telnet session so if there is no
activing for 5 minutes or so it would disconnect.

Regards,

Greg Wood

void Dump_TCP(FILE *data, HANDLE timeout)
{
 unsigned char TCP_data[256];
 int size=0;
 unsigned char i,lines, chars;
 int end_of_file=1;
 
 NutSleep(125);
 HANDLE timer1;
 printf("Displaying Socket Data\n");
 reset_timer(&disconnect_timeout);
 TCP_timeout=0;


 for(;;)
  {
  fflush(data);
  
  PORTB|=0x40;
  while(size==0&&TCP_timeout==0)		           <----PROBLEM
SECTION
   {
   NutThreadYield();
   printf("Size %d %d", size, TCP_timeout);
   size=fread(TCP_data, 1, sizeof(TCP_data), data);

   }
  PORTB&=0x40;
    
  if(TCP_timeout==1)
   {
   TCP_timeout=0;
   printf("disconnect timeout\n");
   break;
   }
  //size=fread(TCP_data, 1, sizeof(TCP_data), data);
  //if(size==0)
  // continue;
  reset_timer(&disconnect_timeout);
  lines=size>>3;
  chars=size&0x07;
  for(i=0;i<lines;i++)
   {
   printf("%02X %02X %02X %02X %02X %02X %02X %02X\n", TCP_data[i*8],
TCP_data[i*8+1],TCP_data[i*8+2],TCP_data[i*8+3],TCP_data[i*8+4],TCP_data
[i*8+5],TCP_data[i*8+6],TCP_data[i*8+7]);
   //fprintf(data,"%02X %02X %02X %02X %02X %02X %02X %02X\n",
TCP_data[i*8],
TCP_data[i*8+1],TCP_data[i*8+2],TCP_data[i*8+3],TCP_data[i*8+4],TCP_data
[i*8+5],TCP_data[i*8+6],TCP_data[i*8+7]);
   }
  lines<<=3;
  for(i=0;i<chars;i++)
   {
   printf("%02X ",TCP_data[lines+i]);
   //fprintf(data,"%02X ",TCP_data[lines+i]);
   }
  printf("\n");
  //fputs(TCP_data, data);
  size=0;

  }
}


THREAD (TCP,arg)
{
    TCPSOCKET *port;
    FILE *data;

 user_timer_start(1000,1,&disconnect_timeout,&disconnect,0);
 for(;;)
 {
 
 printf("Creating socket on 12345\n");
        port = NutTcpCreateSocket();
        NutTcpAccept(port, 12345);
        data = _fdopen((int) port, "r+b");
  //reset_timer(timeout);
  Dump_TCP(data,arg);
  fclose(data);
  NutTcpCloseSocket(port);
 }
}

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