release/src/router/nettle/base64-decode.c

   1 /* base64-encode.c
   2  *
   3  */
   4
   5 /* nettle, low-level cryptographics library
   6  *
   7  * Copyright (C) 2002 Niels Möller
   8  *
   9  * The nettle library is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or (at your
  12  * option) any later version.
  13  *
  14  * The nettle library is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  16  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  17  * License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  22  * MA 02111-1301, USA.
  23  */
  24
  25 #if HAVE_CONFIG_H
  26 # include "config.h"
  27 #endif
  28
  29 #include <assert.h>
  30 #include <stdlib.h>
  31
  32 #include "base64.h"
  33
  34 #define TABLE_INVALID -1
  35 #define TABLE_SPACE -2
  36 #define TABLE_END -3
  37
  38 static const signed char
  39 decode_table[0x100] =
  40 {
  41   /* White space is HT, VT, FF, CR, LF and SPC */
  42   -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2, -1, -1,
  43   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  44   -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
  45   52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1,
  46   -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
  47   15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
  48   -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  49   41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
  50   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  51   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  52   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  53   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  54   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  55   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  56   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  57   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  58 };
  59
  60 void
  61 base64_decode_init(struct base64_decode_ctx *ctx)
  62 {
  63   ctx->word = ctx->bits = ctx->padding = 0;
  64 }
  65
  66 int
  67 base64_decode_single(struct base64_decode_ctx *ctx,
  68                      uint8_t *dst,
  69                      uint8_t src)
  70 {
  71   int data;
  72
  73   data = decode_table[src];
  74
  75   switch(data)
  76     {
  77     default:
  78       assert(data >= 0 && data < 0x40);
  79
  80       if (ctx->padding)
  81         return -1;
  82
  83       ctx->word = ctx->word << 6 | data;
  84       ctx->bits += 6;
  85
  86       if (ctx->bits >= 8)
  87         {
  88           ctx->bits -= 8;
  89           dst[0] = ctx->word >> ctx->bits;
  90           return 1;
  91         }
  92       else return 0;
  93
  94     case TABLE_INVALID:
  95       return -1;
  96
  97     case TABLE_SPACE:
  98       return 0;
  99
 100     case TABLE_END:
 101       /* There can be at most two padding characters. */
 102       if (!ctx->bits || ctx->padding > 2)
 103         return -1;
 104
 105       if (ctx->word & ( (1<<ctx->bits) - 1))
 106         /* We shouldn't have any leftover bits */
 107         return -1;
 108
 109       ctx->padding++;
 110       ctx->bits -= 2;
 111       return 0;
 112     }
 113 }
 114
 115 int
 116 base64_decode_update(struct base64_decode_ctx *ctx,
 117                      unsigned *dst_length,
 118                      uint8_t *dst,
 119                      unsigned src_length,
 120                      const uint8_t *src)
 121 {
 122   unsigned done;
 123   unsigned i;
 124
 125   assert(*dst_length >= BASE64_DECODE_LENGTH(src_length));
 126
 127   for (i = 0, done = 0; i<src_length; i++)
 128     switch(base64_decode_single(ctx, dst + done, src[i]))
 129       {
 130       case -1:
 131         return 0;
 132       case 1:
 133         done++;
 134         /* Fall through */
 135       case 0:
 136         break;
 137       default:
 138         abort();
 139       }
 140
 141   assert(done <= BASE64_DECODE_LENGTH(src_length));
 142
 143   *dst_length = done;
 144   return 1;
 145 }
 146
 147 int
 148 base64_decode_final(struct base64_decode_ctx *ctx)
 149 {
 150   return ctx->bits == 0;
 151 }