path: root/src/psk.c

/*
 * Copyright (C) 2005-2012 Free Software Foundation, Inc.
 *
 * This file is part of GnuTLS.
 *
 * GnuTLS is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuTLS 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see
 * <http://www.gnu.org/licenses/>.
 */

#include <config.h>

/* Gnulib portability files. */

#ifndef ENABLE_PSK

#include <stdio.h>

int
main (int argc, char **argv)
{
  printf ("\nPSK not supported. This program is a dummy.\n\n");
  return 1;
};

#else

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <gnutls/gnutls.h>
#include <psk-args.h>

#include <gnutls/crypto.h>      /* for random */

#include <sys/types.h>
#include <sys/stat.h>

#ifndef _WIN32
#include <pwd.h>
#include <unistd.h>
#else
#include <windows.h>
#endif

/* Gnulib portability files. */
#include <minmax.h>
#include "getpass.h"

static int write_key (const char *username, const char *key, int key_size,
                      const char *passwd_file);

#define KPASSWD "/etc/passwd.psk"
#define MAX_KEY_SIZE 64
int
main (int argc, char **argv)
{
  int ret;
#ifndef _WIN32
  struct passwd *pwd;
#endif
  unsigned char key[MAX_KEY_SIZE];
  char hex_key[MAX_KEY_SIZE * 2 + 1];
  int optct, key_size;
  gnutls_datum_t dkey;
  const char* passwd, *username;
  size_t hex_key_size = sizeof (hex_key);

  if ((ret = gnutls_global_init ()) < 0)
    {
      fprintf (stderr, "global_init: %s\n", gnutls_strerror (ret));
      exit (1);
    }

  umask (066);

  optct = optionProcess( &psktoolOptions, argc, argv);
  argc -= optct;
  argv += optct;

  if (!HAVE_OPT(PASSWD))
    passwd = (char *) KPASSWD;
  else
    passwd = OPT_ARG(PASSWD);

  if (!HAVE_OPT(USERNAME))
    {
#ifndef _WIN32
      pwd = getpwuid (getuid ());

      if (pwd == NULL)
        {
          fprintf (stderr, "No such user\n");
          return -1;
        }

      username = pwd->pw_name;
#else
      fprintf (stderr, "Please specify a user\n");
      return -1;
#endif
    }
  else
    username = OPT_ARG(USERNAME);

  if (HAVE_OPT(KEYSIZE) && OPT_VALUE_KEYSIZE > MAX_KEY_SIZE)
    {
      fprintf (stderr, "Key size is too long\n");
      exit (1);
    }

  if (!HAVE_OPT(KEYSIZE) || OPT_VALUE_KEYSIZE < 1)
    key_size = 16;
  else
    key_size = OPT_VALUE_KEYSIZE;

  printf ("Generating a random key for user '%s'\n", username);

  ret = gnutls_rnd (GNUTLS_RND_RANDOM, (char *) key, key_size);
  if (ret < 0)
    {
      fprintf (stderr, "Not enough randomness\n");
      exit (1);
    }

  dkey.data = key;
  dkey.size = key_size;

  ret = gnutls_hex_encode (&dkey, hex_key, &hex_key_size);
  if (ret < 0)
    {
      fprintf (stderr, "HEX encoding error\n");
      exit (1);
    }

  ret = write_key (username, hex_key, hex_key_size, passwd);
  if (ret == 0)
    printf ("Key stored to %s\n", passwd);

  return ret;
}

static int
filecopy (const char *src, const char *dst)
{
  FILE *fd, *fd2;
  char line[5 * 1024];
  char *p;

  fd = fopen (dst, "w");
  if (fd == NULL)
    {
      fprintf (stderr, "Cannot open '%s' for write\n", dst);
      return -1;
    }

  fd2 = fopen (src, "r");
  if (fd2 == NULL)
    {
      /* empty file */
      fclose (fd);
      return 0;
    }

  line[sizeof (line) - 1] = 0;
  do
    {
      p = fgets (line, sizeof (line) - 1, fd2);
      if (p == NULL)
        break;

      fputs (line, fd);
    }
  while (1);

  fclose (fd);
  fclose (fd2);

  return 0;
}

static int
write_key (const char *username, const char *key, int key_size,
           const char *passwd_file)
{
  FILE *fd;
  char line[5 * 1024];
  char *p, *pp;
  char tmpname[1024];


  /* delete previous entry */
  struct stat st;
  FILE *fd2;
  int put;

  if (strlen (passwd_file) + 5 > sizeof (tmpname))
    {
      fprintf (stderr, "file '%s' is tooooo long\n", passwd_file);
      return -1;
    }

  snprintf (tmpname, sizeof(tmpname), "%s.tmp", passwd_file);

  if (stat (tmpname, &st) != -1)
    {
      fprintf (stderr, "file '%s' is locked\n", tmpname);
      return -1;
    }

  if (filecopy (passwd_file, tmpname) != 0)
    {
      fprintf (stderr, "Cannot copy '%s' to '%s'\n", passwd_file, tmpname);
      return -1;
    }

  fd = fopen (passwd_file, "w");
  if (fd == NULL)
    {
      fprintf (stderr, "Cannot open '%s' for write\n", passwd_file);
      remove (tmpname);
      return -1;
    }

  fd2 = fopen (tmpname, "r");
  if (fd2 == NULL)
    {
      fprintf (stderr, "Cannot open '%s' for read\n", tmpname);
      remove (tmpname);
      return -1;
    }

  put = 0;
  do
    {
      p = fgets (line, sizeof (line) - 1, fd2);
      if (p == NULL)
        break;

      pp = strchr (line, ':');
      if (pp == NULL)
        continue;

      if (strncmp (p, username,
                   MAX (strlen (username), (unsigned int) (pp - p))) == 0)
        {
          put = 1;
          fprintf (fd, "%s:%s\n", username, key);
        }
      else
        {
          fputs (line, fd);
        }
    }
  while (1);

  if (put == 0)
    {
      fprintf (fd, "%s:%s\n", username, key);
    }

  fclose (fd);
  fclose (fd2);

  remove (tmpname);


  return 0;
}

#endif /* ENABLE_PSK */