libavutil/base64.c

   1 /*
   2  * Copyright (c) 2006 Ryan Martell. (rdm4@martellventures.com)
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * @brief Base64 encode/decode
  24  * @author Ryan Martell <rdm4@martellventures.com> (with lots of Michael)
  25  */
  26
  27 #include <limits.h>
  28 #include <stddef.h>
  29
  30 #include "base64.h"
  31 #include "error.h"
  32 #include "intreadwrite.h"
  33
  34 /* ---------------- private code */
  35 static const uint8_t map2[256] =
  36 {
  37     0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  38     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  39     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  40     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  41     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  42     0xff, 0xff, 0xff,
  43
  44     0x3e, 0xff, 0xff, 0xff, 0x3f, 0x34, 0x35, 0x36,
  45     0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0xff,
  46     0xff, 0xff, 0xfe, 0xff, 0xff, 0xff, 0x00, 0x01,
  47     0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
  48     0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11,
  49     0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
  50     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1a, 0x1b,
  51     0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
  52     0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
  53     0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33,
  54
  55                       0xff, 0xff, 0xff, 0xff, 0xff,
  56     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  57     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  58     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  59     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  60     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  61     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  62     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  63     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  64     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  65     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  66     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  67     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  68     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  69     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  70     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  71     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  72 };
  73
  74 #define BASE64_DEC_STEP(i) do { \
  75     bits = map2[in[i]]; \
  76     if (bits & 0x80) \
  77         goto out ## i; \
  78     v = i ? (v << 6) + bits : bits; \
  79 } while(0)
  80
  81 int av_base64_decode(uint8_t *out, const char *in_str, int out_size)
  82 {
  83     uint8_t *dst = out;
  84     uint8_t *end;
  85     // no sign extension
  86     const uint8_t *in = in_str;
  87     unsigned bits = 0xff;
  88     unsigned v;
  89
  90     if (!out)
  91         goto validity_check;
  92
  93     end = out + out_size;
  94     while (end - dst > 3) {
  95         BASE64_DEC_STEP(0);
  96         BASE64_DEC_STEP(1);
  97         BASE64_DEC_STEP(2);
  98         BASE64_DEC_STEP(3);
  99         // Using AV_WB32 directly confuses compiler
 100         v = av_be2ne32(v << 8);
 101         AV_WN32(dst, v);
 102         dst += 3;
 103         in += 4;
 104     }
 105     if (end - dst) {
 106         BASE64_DEC_STEP(0);
 107         BASE64_DEC_STEP(1);
 108         BASE64_DEC_STEP(2);
 109         BASE64_DEC_STEP(3);
 110         *dst++ = v >> 16;
 111         if (end - dst)
 112             *dst++ = v >> 8;
 113         if (end - dst)
 114             *dst++ = v;
 115         in += 4;
 116     }
 117 validity_check:
 118     while (1) {
 119         BASE64_DEC_STEP(0);
 120         in++;
 121         BASE64_DEC_STEP(0);
 122         in++;
 123         BASE64_DEC_STEP(0);
 124         in++;
 125         BASE64_DEC_STEP(0);
 126         in++;
 127     }
 128
 129 out3:
 130     if (end - dst)
 131         *dst++ = v >> 10;
 132     v <<= 2;
 133 out2:
 134     if (end - dst)
 135         *dst++ = v >> 4;
 136 out1:
 137 out0:
 138     return bits & 1 ? AVERROR_INVALIDDATA : out ? dst - out : 0;
 139 }
 140
 141 /*****************************************************************************
 142 * b64_encode: Stolen from VLC's http.c.
 143 * Simplified by Michael.
 144 * Fixed edge cases and made it work from data (vs. strings) by Ryan.
 145 *****************************************************************************/
 146
 147 char *av_base64_encode(char *out, int out_size, const uint8_t *in, int in_size)
 148 {
 149     static const char b64[] =
 150         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 151     char *ret, *dst;
 152     unsigned i_bits = 0;
 153     int i_shift = 0;
 154     int bytes_remaining = in_size;
 155
 156     if (in_size >= UINT_MAX / 4 ||
 157         out_size < AV_BASE64_SIZE(in_size))
 158         return NULL;
 159     ret = dst = out;
 160     while (bytes_remaining > 3) {
 161         i_bits = AV_RB32(in);
 162         in += 3; bytes_remaining -= 3;
 163         *dst++ = b64[ i_bits>>26        ];
 164         *dst++ = b64[(i_bits>>20) & 0x3F];
 165         *dst++ = b64[(i_bits>>14) & 0x3F];
 166         *dst++ = b64[(i_bits>>8 ) & 0x3F];
 167     }
 168     i_bits = 0;
 169     while (bytes_remaining) {
 170         i_bits = (i_bits << 8) + *in++;
 171         bytes_remaining--;
 172         i_shift += 8;
 173     }
 174     while (i_shift > 0) {
 175         *dst++ = b64[(i_bits << 6 >> i_shift) & 0x3f];
 176         i_shift -= 6;
 177     }
 178     while ((dst - ret) & 3)
 179         *dst++ = '=';
 180     *dst = '\0';
 181
 182     return ret;
 183 }