loop.c

/*
     This file (was) part of GNUnet.
     Copyright (C) 2018 Christian Grothoff

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file loop.c
 * @brief Sample implementation of the main loop for interacting with the parent
 * @author Christian Grothoff
 */


/**
 * Sample main loop.  Reads packets from STDIN_FILENO
 * and calls handle_mac(), handle_control() or handle_frame()
 * on each depending on the type.
 */
static void
loop ()
{
  char buf[UINT16_MAX];
  size_t off;
  ssize_t ret;
  int have_mac;

  off = 0;
  have_mac = 0;
  while (-1 != (ret = read (STDIN_FILENO,
                            &buf[off],
                            sizeof (buf) - off)))
    {
      struct GLAB_MessageHeader hdr;
      uint16_t size;

      if (0 >= ret)
	break;
      off += ret;
      while (off > sizeof (struct GLAB_MessageHeader))
	{
	  memcpy (&hdr,
		  buf,
		  sizeof (hdr));
	  size = ntohs (hdr.size);
	  if (off < size)
	    break;
          if (size < sizeof (struct GLAB_MessageHeader))
            abort ();
	  switch (ntohs (hdr.type)) {
	  case 0: /* control */
	    if (0 == have_mac)
	      {
		for (unsigned int i=0;i<(size - sizeof (hdr)) / sizeof (struct MacAddress);i++)
		  {
		    struct MacAddress mac;

		    memcpy (&mac,
			    &buf[sizeof (hdr) + i * sizeof (struct MacAddress)],
			    sizeof (struct MacAddress));
		    handle_mac (i + 1,
				&mac);
		  }
		have_mac = 1;
	      }
	    else
	      {
		handle_control (&buf[sizeof (hdr)],
				size - sizeof (hdr));
	      }
	    break;
	  default:
	    handle_frame (ntohs (hdr.type),
			  (const void *) &buf[sizeof (hdr)],
			  size - sizeof (hdr));
	    break;
	  }
	  memmove (buf,
		   &buf[size],
		   off - size);
	  off -= size;
	}
    }
}