lib/base64.c

   1 /*
   2  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /*
  10 * Copied from Nettle 3.0 under GPLv2, with adjustments
  11  */
  12
  13 #include "squid.h"
  14 #include "base64.h"
  15
  16 #if !HAVE_NETTLE_BASE64_H || !HAVE_NETTLE30_BASE64
  17
  18 #if HAVE_STDLIB_H
  19 #include <stdlib.h>
  20 #endif
  21
  22 static const uint8_t encode_table[64] =
  23     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
  24     "abcdefghijklmnopqrstuvwxyz"
  25     "0123456789+/";
  26
  27 #define ENCODE(x) (encode_table[0x3F & (x)])
  28
  29 static const signed char decode_table[0x100] =
  30 {
  31     /* White space is HT, VT, FF, CR, LF and SPC */
  32     -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2, -1, -1,
  33     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  34     -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
  35     52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1,
  36     -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
  37     15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
  38     -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  39     41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
  40     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  41     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  42     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  43     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  44     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  45     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  46     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  47     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
  48 };
  49
  50 #define TABLE_INVALID -1
  51 #define TABLE_SPACE -2
  52 #define TABLE_END -3
  53
  54 #define BASE64_VALUE_SZ 256
  55 int base64_value[BASE64_VALUE_SZ];
  56
  57 void
  58 base64_decode_init(struct base64_decode_ctx *ctx)
  59 {
  60     ctx->word = ctx->bits = ctx->padding = 0;
  61 }
  62
  63 static int
  64 base64_decode_single(struct base64_decode_ctx *ctx, uint8_t *dst, uint8_t src)
  65 {
  66     int data = decode_table[src];
  67
  68     switch(data) {
  69     default:
  70         assert(data >= 0 && data < 0x40);
  71
  72         if (ctx->padding)
  73             return -1;
  74
  75         ctx->word = ctx->word << 6 | data;
  76         ctx->bits += 6;
  77
  78         if (ctx->bits >= 8) {
  79             ctx->bits -= 8;
  80             dst[0] = ctx->word >> ctx->bits;
  81             return 1;
  82         } else
  83             return 0;
  84
  85     case TABLE_INVALID:
  86         return -1;
  87
  88     case TABLE_SPACE:
  89         return 0;
  90
  91     case TABLE_END:
  92         /* There can be at most two padding characters. */
  93         if (!ctx->bits || ctx->padding > 2)
  94             return -1;
  95
  96         if (ctx->word & ( (1<<ctx->bits) - 1))
  97             /* We shouldn't have any leftover bits */
  98             return -1;
  99
 100         ctx->padding++;
 101         ctx->bits -= 2;
 102         return 0;
 103     }
 104 }
 105
 106 int
 107 base64_decode_update(struct base64_decode_ctx *ctx,
 108                      size_t *dst_length,
 109                      uint8_t *dst,
 110                      size_t src_length,
 111                      const uint8_t *src)
 112 {
 113     size_t done;
 114     size_t i;
 115
 116     for (i = 0, done = 0; i < src_length; i++) {
 117         switch(base64_decode_single(ctx, dst + done, src[i])) {
 118         case -1:
 119             return 0;
 120         case 1:
 121             done++;
 122         /* Fall through */
 123         case 0:
 124             break;
 125         default:
 126             abort();
 127         }
 128     }
 129
 130     assert(done <= BASE64_DECODE_LENGTH(src_length));
 131
 132     *dst_length = done;
 133     return 1;
 134 }
 135
 136 int
 137 base64_decode_final(struct base64_decode_ctx *ctx)
 138 {
 139     return ctx->bits == 0;
 140 }
 141
 142 static void
 143 base64_encode_raw(uint8_t *dst, size_t length, const uint8_t *src)
 144 {
 145     const uint8_t *in = src + length;
 146     uint8_t *out = dst + BASE64_ENCODE_RAW_LENGTH(length);
 147
 148     unsigned left_over = length % 3;
 149
 150     if (left_over) {
 151         in -= left_over;
 152         *--out = '=';
 153         switch(left_over) {
 154         case 1:
 155             *--out = '=';
 156             *--out = ENCODE(in[0] << 4);
 157             break;
 158
 159         case 2:
 160             *--out = ENCODE( in[1] << 2);
 161             *--out = ENCODE((in[0] << 4) | (in[1] >> 4));
 162             break;
 163
 164         default:
 165             abort();
 166         }
 167         *--out = ENCODE(in[0] >> 2);
 168     }
 169
 170     while (in > src) {
 171         in -= 3;
 172         *--out = ENCODE( in[2]);
 173         *--out = ENCODE((in[1] << 2) | (in[2] >> 6));
 174         *--out = ENCODE((in[0] << 4) | (in[1] >> 4));
 175         *--out = ENCODE( in[0] >> 2);
 176     }
 177     assert(in == src);
 178     assert(out == dst);
 179 }
 180
 181 void
 182 base64_encode_init(struct base64_encode_ctx *ctx)
 183 {
 184     ctx->word = ctx->bits = 0;
 185 }
 186
 187 /* Encodes a single byte. */
 188 size_t
 189 base64_encode_single(struct base64_encode_ctx *ctx,
 190                      uint8_t *dst,
 191                      uint8_t src)
 192 {
 193     unsigned done = 0;
 194     unsigned word = ctx->word << 8 | src;
 195     unsigned bits = ctx->bits + 8;
 196
 197     while (bits >= 6) {
 198         bits -= 6;
 199         dst[done++] = ENCODE(word >> bits);
 200     }
 201
 202     ctx->bits = bits;
 203     ctx->word = word;
 204
 205     assert(done <= 2);
 206
 207     return done;
 208 }
 209
 210 /* Returns the number of output characters. DST should point to an
 211  * area of size at least BASE64_ENCODE_LENGTH(length). */
 212 size_t
 213 base64_encode_update(struct base64_encode_ctx *ctx,
 214                      uint8_t *dst,
 215                      size_t length,
 216                      const uint8_t *src)
 217 {
 218     size_t done = 0;
 219     size_t left = length;
 220     unsigned left_over;
 221     size_t bulk;
 222
 223     while (ctx->bits && left) {
 224         left--;
 225         done += base64_encode_single(ctx, dst + done, *src++);
 226     }
 227
 228     left_over = left % 3;
 229     bulk = left - left_over;
 230
 231     if (bulk) {
 232         assert(!(bulk % 3));
 233
 234         base64_encode_raw(dst + done, bulk, src);
 235         done += BASE64_ENCODE_RAW_LENGTH(bulk);
 236         src += bulk;
 237         left = left_over;
 238     }
 239
 240     while (left) {
 241         left--;
 242         done += base64_encode_single(ctx, dst + done, *src++);
 243     }
 244
 245     assert(done <= BASE64_ENCODE_LENGTH(length));
 246
 247     return done;
 248 }
 249
 250 /* DST should point to an area of size at least
 251  * BASE64_ENCODE_FINAL_SIZE */
 252 size_t
 253 base64_encode_final(struct base64_encode_ctx *ctx,
 254                     uint8_t *dst)
 255 {
 256     unsigned done = 0;
 257     unsigned bits = ctx->bits;
 258
 259     if (bits) {
 260         dst[done++] = ENCODE(ctx->word << (6 - ctx->bits));
 261         for (; bits < 6; bits += 2)
 262             dst[done++] = '=';
 263
 264         ctx->bits = 0;
 265     }
 266
 267     assert(done <= BASE64_ENCODE_FINAL_LENGTH);
 268     return done;
 269 }
 270
 271 #endif /* !HAVE_NETTLE_BASE64_H || !HAVE_NETTLE30_BASE64 */
 272