[En-Nut-Discussion] Telnet server with echo and cursor key support

[Hugo Simon]

Hi.

Now I have built a simple read line function that reads a line of characters
from a stream, supporting the BS key and an echo. It works fine on
stdin/stdout routed to the uart0 device. But with a TCP Telnet socket
connected to a stream there came some unreadable characters on connection
and on pressing return. I don't know why. Maybe someone have a look at the
code and give me some hint.

Thank you
Thorsten

/*
 * read a line from a stream with echo and BS support
 */
void readln(char *line, u_char len, FILE *stream)
{
 u_char x=0;
  char ch;
  *line=0;
  do
  {
    ch=fgetc(stream);
    switch (ch)
    {
      case 8:
        if (x>0)
        {
          line[--x]=0;
          fputc(ch,stream);
          fputc(' ',stream);
          fputc(ch,stream);
        }
        break;
      case '\n':
        fputs("\n",stream);
        break;
      default:
          if ((ch>=0x20) && (ch<=0x80))
          {
          if (x<len)
          {
            fputc(ch,stream);
            line[x++]=ch;
            line[x]=0;
          }
        }
    }
  } while (ch!='\n');
}

/*
 * Process client telnet requests.
 */
void ProcessRequests(FILE *stream)
{
  static char buff[128];
  /*
   * Send a welcome banner.
   */
  fputs_P(banner_P, stream);
  for(;;)
  {
   /*
    * Flush output and read a line.
    */
   fflush(stream);
   readln(buff, sizeof(buff), stream);
   puts(buff);
   file://Processline(buff,stream);
 }
}

/*
 * Telnet Server Thread
 */
THREAD(Telnet, arg)
{
  TCPSOCKET *sock;
  FILE *stream;

  /* loop endless for connections. */
  puts("Starting Telnet Daemon...");
  for(;;)
  {
    /* Create a socket. */
   if ((sock = NutTcpCreateSocket()) != 0)
   {
     /* Listen on port 23. If we return, we got a client. */
     printf("Waiting for a telnet client...");
     if (NutTcpAccept(sock, 23) == 0)
     {
      puts("connected");

       /*
       * Open a stream and associate it with the socket, so
       * we can use standard I/O. Note, that socket streams
       * currently do support text mode.
        */
       if((stream = _fdopen((int)sock, "r+b")) != 0)
       {
         /* Process client requests. */
        ProcessRequests(stream);
        puts("Disconnected");

        /* Close the stream. */
        fclose(stream);
      }
      else
        puts("Assigning a stream failed");
     }
     else
      puts("failed");

      /* Close our socket. */
     NutTcpCloseSocket(sock);
   }
  }
}