src/home/modhex.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4
   5 #include "modhex.h"
   6 #include "macro.h"
   7 #include "memory-util.h"
   8
   9 const char modhex_alphabet[16] = {
  10         'c', 'b', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'n', 'r', 't', 'u', 'v'
  11 };
  12
  13 int decode_modhex_char(char x) {
  14
  15         for (size_t i = 0; i < ELEMENTSOF(modhex_alphabet); i++)
  16                 /* Check both upper and lowercase */
  17                 if (modhex_alphabet[i] == x || (modhex_alphabet[i] - 32) == x)
  18                         return i;
  19
  20         return -EINVAL;
  21 }
  22
  23 int normalize_recovery_key(const char *password, char **ret) {
  24         _cleanup_(erase_and_freep) char *mangled = NULL;
  25         size_t l;
  26
  27         assert(password);
  28         assert(ret);
  29
  30         l = strlen(password);
  31         if (!IN_SET(l,
  32                     MODHEX_RAW_LENGTH*2,          /* syntax without dashes */
  33                     MODHEX_FORMATTED_LENGTH-1))   /* syntax with dashes */
  34                 return -EINVAL;
  35
  36         mangled = new(char, MODHEX_FORMATTED_LENGTH);
  37         if (!mangled)
  38                 return -ENOMEM;
  39
  40         for (size_t i = 0, j = 0; i < MODHEX_RAW_LENGTH; i++) {
  41                 size_t k;
  42                 int a, b;
  43
  44                 if (l == MODHEX_RAW_LENGTH*2)
  45                         /* Syntax without dashes */
  46                         k = i * 2;
  47                 else {
  48                         /* Syntax with dashes */
  49                         assert(l == MODHEX_FORMATTED_LENGTH-1);
  50                         k = i * 2 + i / 4;
  51
  52                         if (i > 0 && i % 4 == 0 && password[k-1] != '-')
  53                                 return -EINVAL;
  54                 }
  55
  56                 a = decode_modhex_char(password[k]);
  57                 if (a < 0)
  58                         return -EINVAL;
  59                 b = decode_modhex_char(password[k+1]);
  60                 if (b < 0)
  61                         return -EINVAL;
  62
  63                 mangled[j++] = modhex_alphabet[a];
  64                 mangled[j++] = modhex_alphabet[b];
  65
  66                 if (i % 4 == 3)
  67                         mangled[j++] = '-';
  68         }
  69
  70         mangled[MODHEX_FORMATTED_LENGTH-1] = 0;
  71
  72         *ret = TAKE_PTR(mangled);
  73         return 0;
  74 }