wsutil/base32.c

   1 /* base32.c
   2  * Base-32 conversion
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 #include "config.h"
  12 #include "base32.h"
  13
  14 #include <string.h>
  15
  16 /*
  17  * Cjdns style base32 encoding
  18  */
  19
  20 /** Returned by ws_base32_encode() if the input is not valid base32. */
  21 #define Base32_BAD_INPUT -1
  22 /** Returned by ws_base32_encode() if the output buffer is too small. */
  23 #define Base32_TOO_BIG -2
  24
  25 int ws_base32_decode(uint8_t* output, const uint32_t outputLength,
  26                                                 const uint8_t* in, const uint32_t inputLength)
  27 {
  28         uint32_t outIndex = 0;
  29         uint32_t inIndex = 0;
  30         uint32_t work = 0;
  31         uint32_t bits = 0;
  32         static const uint8_t* kChars = (uint8_t*) "0123456789bcdfghjklmnpqrstuvwxyz";
  33         while (inIndex < inputLength) {
  34                 work |= ((unsigned) in[inIndex++]) << bits;
  35                 bits += 8;
  36                 while (bits >= 5) {
  37                         if (outIndex >= outputLength) {
  38                                 return Base32_TOO_BIG;
  39                         }
  40                         output[outIndex++] = kChars[work & 31];
  41                         bits -= 5;
  42                         work >>= 5;
  43                 }
  44         }
  45         if (bits) {
  46                 if (outIndex >= outputLength) {
  47                         return Base32_TOO_BIG;
  48                 }
  49                 output[outIndex++] = kChars[work & 31];
  50         }
  51         if (outIndex < outputLength) {
  52                 output[outIndex] = '\0';
  53         }
  54         return outIndex;
  55 }
  56
  57 /*
  58  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  59  *
  60  * Local variables:
  61  * c-basic-offset: 8
  62  * tab-width: 8
  63  * indent-tabs-mode: t
  64  * End:
  65  *
  66  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
  67  * :indentSize=8:tabSize=8:noTabs=false:
  68  */