/*
 * Copyright (c) 2005, 2006 Thorsten Kukuk <kukuk@suse.de>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, and the entire permission notice in its entirety,
 *    including the disclaimer of warranties.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * ALTERNATIVELY, this product may be distributed under the terms of
 * the GNU Public License, in which case the provisions of the GPL are
 * required INSTEAD OF the above restrictions.  (This clause is
 * necessary due to a potential bad interaction between the GPL and
 * the restrictions contained in a BSD-style copyright.)
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif

#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 255
#endif

#define PAM_SM_ACCOUNT
#define PAM_SM_AUTH
#define PAM_SM_PASSWORD
#define PAM_SM_SESSION

#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <security/_pam_macros.h>
#include <security/pam_ext.h>

static int
replace_and_print (pam_handle_t *pamh, const char *mesg)
{
  char *output;
  size_t length = strlen (mesg) + PAM_MAX_MSG_SIZE;
  char myhostname[HOST_NAME_MAX+1];
  const void *str = NULL;
  const char *p, *q;
  int item;
  size_t len;

  output = malloc (length);
  if (output == NULL)
    {
      pam_syslog (pamh, LOG_CRIT, "running out of memory");
      return PAM_BUF_ERR;
    }

  for (p = mesg, len = 0; *p != '\0' && len < length - 1; ++p)
    {
      if (*p != '%' || p[1] == '\0')
	{
	  output[len++] = *p;
	  continue;
	}
      switch (*++p)
	{
	case 'H':
	  item = PAM_RHOST;
	  break;
	case 'h':
	  item = -2; /* aka PAM_LOCALHOST */
	  break;
	case 's':
	  item = PAM_SERVICE;
	  break;
	case 't':
	  item = PAM_TTY;
	  break;
	case 'U':
	  item = PAM_RUSER;
	  break;
	case 'u':
	  item = PAM_USER;
	  break;
	default:
	  output[len++] = *p;
	  continue;
	}
      if (item == -2)
	{
	  if (gethostname (myhostname, sizeof (myhostname)) == -1)
	    str = NULL;
	  else
	    str = &myhostname;
	}
      else
	{
	  if (pam_get_item (pamh, item, &str) != PAM_SUCCESS)
	    str = NULL;
	}
      if (str == NULL)
	str = "(null)";
      for (q = str; *q != '\0' && len < length - 1; ++q)
	output[len++] = *q;
    }
  output[len] = '\0';

  pam_info (pamh, "%s", output);
  free (output);

  return PAM_SUCCESS;
}

static int
pam_echo (pam_handle_t *pamh, int flags, int argc, const char **argv)
{
  int fd;
  int orig_argc = argc;
  const char **orig_argv = argv;
  const char *file = NULL;
  int retval;

  if (flags & PAM_SILENT)
    return PAM_IGNORE;

  for (; argc-- > 0; ++argv)
    {
      if (!strncmp (*argv, "file=", 5))
	file = (5 + *argv);
    }

  /* No file= option, use argument for output.  */
  if (file == NULL || file[0] == '\0')
    {
      char msg[PAM_MAX_MSG_SIZE];
      const char *p;
      int i;
      size_t len;

      for (i = 0, len = 0; i < orig_argc && len < sizeof (msg) - 1; ++i)
	{
	  if (i > 0)
	    msg[len++] = ' ';
	  for (p = orig_argv[i]; *p != '\0' && len < sizeof(msg) - 1; ++p)
	    msg[len++] = *p;
	}
      msg[len] = '\0';

      retval = replace_and_print (pamh, msg);
    }
  else if ((fd = open (file, O_RDONLY, 0)) >= 0)
    {
      char *mtmp = NULL;
      struct stat st;

      /* load file into message buffer. */
      if ((fstat (fd, &st) < 0) || !st.st_size)
	{
	  close (fd);
	  return PAM_IGNORE;
	}

      mtmp = malloc (st.st_size + 1);
      if (!mtmp)
	{
	  close (fd);
	  return PAM_BUF_ERR;
	}

      if (pam_modutil_read (fd, mtmp, st.st_size) == -1)
	{
	  pam_syslog (pamh, LOG_ERR, "Error while reading %s: %m", file);
	  free (mtmp);
	  close (fd);
	  return PAM_IGNORE;
	}

      if (mtmp[st.st_size - 1] == '\n')
	mtmp[st.st_size - 1] = '\0';
      else
	mtmp[st.st_size] = '\0';

      close (fd);
      retval = replace_and_print (pamh, mtmp);
      free (mtmp);
    }
  else
    {
       pam_syslog (pamh, LOG_ERR, "Cannot open %s: %m", file);
       retval = PAM_IGNORE;
    }
  return retval;
}

int
pam_sm_authenticate (pam_handle_t *pamh, int flags, int argc,
                     const char **argv)
{
  return pam_echo (pamh, flags, argc, argv);
}

int
pam_sm_setcred (pam_handle_t *pamh UNUSED, int flags UNUSED,
		int argc UNUSED, const char **argv UNUSED)
{
  return PAM_IGNORE;
}

int
pam_sm_acct_mgmt (pam_handle_t *pamh, int flags, int argc,
		  const char **argv)
{
  return pam_echo (pamh, flags, argc, argv);
}

int
pam_sm_open_session (pam_handle_t *pamh, int flags, int argc,
		     const char **argv)
{
  return pam_echo (pamh, flags, argc, argv);
}

int
pam_sm_close_session (pam_handle_t *pamh UNUSED, int flags UNUSED,
		      int argc UNUSED, const char **argv UNUSED)
{
  return PAM_IGNORE;
}

int
pam_sm_chauthtok (pam_handle_t *pamh, int flags, int argc,
		  const char **argv)
{
  if (flags & PAM_PRELIM_CHECK)
    return pam_echo (pamh, flags, argc, argv);
  else
    return PAM_IGNORE;
}