/**
 * ns_mxcheck.C: Check MX records for registering email.
 *
 * Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team
 * Rights to this code are as documented in COPYING.
 *
 *
 * Portions of this file were derived from sources bearing the following license:
 * Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team
 * Copyright © 2007 Atheme Development Group
 * Rights to this code are as documented in doc/pod/license.pod.
 *
 * $Id: ns_mxcheck.C,v 1.4 2007/09/16 18:54:43 pippijn Exp $
 */

#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>

#include "atheme.h"
#include <ermyth/module.h>

static char const rcsid[] = "$Id: ns_mxcheck.C,v 1.4 2007/09/16 18:54:43 pippijn Exp $";

REGISTER_MODULE ("nickserv/mxcheck", false, "Jamie L. Penman-Smithson <jamie@slacked.org>");

static int
count_mx (char const * const host)
{
  u_char nsbuf[4096];
  ns_msg amsg;
  int l;

  l = res_query (host, ns_c_any, ns_t_mx, nsbuf, sizeof (nsbuf));

  if (l < 0)
    return 0;
  
  ns_initparse (nsbuf, l, &amsg);
  l = ns_msg_count (amsg, ns_s_an);
  
  return l;
}

static bool
check_registration (sourceinfo_t *si, char const * const account, char const * const email)
{
  char buf[1024];
  int count;

  strlcpy (buf, email, sizeof buf);
  /* char const * const user = */strtok (buf, "@");
  char const * const domain = strtok (NULL, "@");
  count = count_mx (domain);

  if (count > 0)
    /* there are MX records for this domain */
    snoop ("REGISTER: mxcheck: %d MX records for %s", count, domain);
  else
    {
      /* no MX records or error */
      struct hostent *host;

      /* attempt to resolve host (fallback to A) */
      if ((host = gethostbyname (domain)) == NULL)
	{
	  snoop ("REGISTER: mxcheck: no A/MX records for %s - "
                 "REGISTER failed", domain);
	  command_fail (si, fault::noprivs, "Sorry, \2%s\2 does not exist, "
                        "I can't send mail there. Please check and try again.", domain);
	  return false;
	}
    }

  return true;
}

bool
_modinit (module *m)
{
  user_t::callback.can_register.attach (check_registration);

  return true;
}

void
_moddeinit (void)
{
  user_t::callback.can_register.detach (check_registration);
}