src/psk.c

   1 /*
   2  * Copyright (C) 2005-2012 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuTLS.
   5  *
   6  * GnuTLS is free software: you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuTLS is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see
  18  * <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <config.h>
  22
  23 /* Gnulib portability files. */
  24 #include <version-etc.h>
  25 #include <progname.h>
  26
  27 #ifndef ENABLE_PSK
  28
  29 #include <stdio.h>
  30
  31 int
  32 main (int argc, char **argv)
  33 {
  34   printf ("\nPSK not supported. This program is a dummy.\n\n");
  35   return 1;
  36 };
  37
  38 #else
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <stdlib.h>
  43 #include <gnutls/gnutls.h>
  44 #include <psk-args.h>
  45
  46 #include <gnutls/crypto.h>      /* for random */
  47
  48 #include <sys/types.h>
  49 #include <sys/stat.h>
  50
  51 #ifndef _WIN32
  52 #include <pwd.h>
  53 #include <unistd.h>
  54 #else
  55 #include <windows.h>
  56 #endif
  57
  58 /* Gnulib portability files. */
  59 #include <minmax.h>
  60 #include "getpass.h"
  61
  62 static int write_key (const char *username, const char *key, int key_size,
  63                       const char *passwd_file);
  64
  65 #define KPASSWD "/etc/passwd.psk"
  66 #define MAX_KEY_SIZE 64
  67 int
  68 main (int argc, char **argv)
  69 {
  70   int ret;
  71 #ifndef _WIN32
  72   struct passwd *pwd;
  73 #endif
  74   unsigned char key[MAX_KEY_SIZE];
  75   char hex_key[MAX_KEY_SIZE * 2 + 1];
  76   int optct, key_size;
  77   gnutls_datum_t dkey;
  78   const char* passwd, *username;
  79   size_t hex_key_size = sizeof (hex_key);
  80
  81   set_program_name (argv[0]);
  82
  83   if ((ret = gnutls_global_init ()) < 0)
  84     {
  85       fprintf (stderr, "global_init: %s\n", gnutls_strerror (ret));
  86       exit (1);
  87     }
  88
  89   umask (066);
  90
  91   optct = optionProcess( &psktoolOptions, argc, argv);
  92   argc -= optct;
  93   argv += optct;
  94
  95   if (!HAVE_OPT(PASSWD))
  96     passwd = (char *) KPASSWD;
  97   else
  98     passwd = OPT_ARG(PASSWD);
  99
 100   if (!HAVE_OPT(USERNAME))
 101     {
 102 #ifndef _WIN32
 103       pwd = getpwuid (getuid ());
 104
 105       if (pwd == NULL)
 106         {
 107           fprintf (stderr, "No such user\n");
 108           return -1;
 109         }
 110
 111       username = pwd->pw_name;
 112 #else
 113       fprintf (stderr, "Please specify a user\n");
 114       return -1;
 115 #endif
 116     }
 117   else
 118     username = OPT_ARG(USERNAME);
 119
 120   if (HAVE_OPT(KEYSIZE) && OPT_VALUE_KEYSIZE > MAX_KEY_SIZE)
 121     {
 122       fprintf (stderr, "Key size is too long\n");
 123       exit (1);
 124     }
 125
 126   if (!HAVE_OPT(KEYSIZE) || OPT_VALUE_KEYSIZE < 1)
 127     key_size = 16;
 128   else
 129     key_size = OPT_VALUE_KEYSIZE;
 130
 131   printf ("Generating a random key for user '%s'\n", username);
 132
 133   ret = gnutls_rnd (GNUTLS_RND_RANDOM, (char *) key, key_size);
 134   if (ret < 0)
 135     {
 136       fprintf (stderr, "Not enough randomness\n");
 137       exit (1);
 138     }
 139
 140   dkey.data = key;
 141   dkey.size = key_size;
 142
 143   ret = gnutls_hex_encode (&dkey, hex_key, &hex_key_size);
 144   if (ret < 0)
 145     {
 146       fprintf (stderr, "HEX encoding error\n");
 147       exit (1);
 148     }
 149
 150   ret = write_key (username, hex_key, hex_key_size, passwd);
 151   if (ret == 0)
 152     printf ("Key stored to %s\n", passwd);
 153
 154   return ret;
 155 }
 156
 157 static int
 158 filecopy (const char *src, const char *dst)
 159 {
 160   FILE *fd, *fd2;
 161   char line[5 * 1024];
 162   char *p;
 163
 164   fd = fopen (dst, "w");
 165   if (fd == NULL)
 166     {
 167       fprintf (stderr, "Cannot open '%s' for write\n", dst);
 168       return -1;
 169     }
 170
 171   fd2 = fopen (src, "r");
 172   if (fd2 == NULL)
 173     {
 174       /* empty file */
 175       fclose (fd);
 176       return 0;
 177     }
 178
 179   line[sizeof (line) - 1] = 0;
 180   do
 181     {
 182       p = fgets (line, sizeof (line) - 1, fd2);
 183       if (p == NULL)
 184         break;
 185
 186       fputs (line, fd);
 187     }
 188   while (1);
 189
 190   fclose (fd);
 191   fclose (fd2);
 192
 193   return 0;
 194 }
 195
 196 static int
 197 write_key (const char *username, const char *key, int key_size,
 198            const char *passwd_file)
 199 {
 200   FILE *fd;
 201   char line[5 * 1024];
 202   char *p, *pp;
 203   char tmpname[1024];
 204
 205
 206   /* delete previous entry */
 207   struct stat st;
 208   FILE *fd2;
 209   int put;
 210
 211   if (strlen (passwd_file) > sizeof (tmpname) + 5)
 212     {
 213       fprintf (stderr, "file '%s' is tooooo long\n", passwd_file);
 214       return -1;
 215     }
 216   strcpy (tmpname, passwd_file);
 217   strcat (tmpname, ".tmp");
 218
 219   if (stat (tmpname, &st) != -1)
 220     {
 221       fprintf (stderr, "file '%s' is locked\n", tmpname);
 222       return -1;
 223     }
 224
 225   if (filecopy (passwd_file, tmpname) != 0)
 226     {
 227       fprintf (stderr, "Cannot copy '%s' to '%s'\n", passwd_file, tmpname);
 228       return -1;
 229     }
 230
 231   fd = fopen (passwd_file, "w");
 232   if (fd == NULL)
 233     {
 234       fprintf (stderr, "Cannot open '%s' for write\n", passwd_file);
 235       remove (tmpname);
 236       return -1;
 237     }
 238
 239   fd2 = fopen (tmpname, "r");
 240   if (fd2 == NULL)
 241     {
 242       fprintf (stderr, "Cannot open '%s' for read\n", tmpname);
 243       remove (tmpname);
 244       return -1;
 245     }
 246
 247   put = 0;
 248   do
 249     {
 250       p = fgets (line, sizeof (line) - 1, fd2);
 251       if (p == NULL)
 252         break;
 253
 254       pp = strchr (line, ':');
 255       if (pp == NULL)
 256         continue;
 257
 258       if (strncmp (p, username,
 259                    MAX (strlen (username), (unsigned int) (pp - p))) == 0)
 260         {
 261           put = 1;
 262           fprintf (fd, "%s:%s\n", username, key);
 263         }
 264       else
 265         {
 266           fputs (line, fd);
 267         }
 268     }
 269   while (1);
 270
 271   if (put == 0)
 272     {
 273       fprintf (fd, "%s:%s\n", username, key);
 274     }
 275
 276   fclose (fd);
 277   fclose (fd2);
 278
 279   remove (tmpname);
 280
 281
 282   return 0;
 283 }
 284
 285 #endif /* ENABLE_PSK */
 286