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/* from https://github.com/mdornseif/didentd */
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/* public domain
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 * BASE64 on stdin -> converted data on stdout */
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/* arbitrary data on stdin -> BASE64 data on stdout
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 * UNIX's newline convention is used, i.e. one ASCII control-j (10 decimal).
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 *
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 * public domain
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 */
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/* Hacked by [email protected] to be a library function working on memory blocks
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 *
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 */
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static unsigned char alphabet[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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int base64decode(char *dest, const char *src, int l)
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{
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  static char inalphabet[256], decoder[256];
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  static short table_initialized = 0;
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  int i, bits, c, char_count;
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  int rpos;
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  int wpos = 0;
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  if (!table_initialized) {
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    for (i = (sizeof alphabet) - 1; i >= 0; i--) {
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      inalphabet[alphabet[i]] = 1;
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      decoder[alphabet[i]] = i;
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    }
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    table_initialized = 1;
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  }
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  char_count = 0;
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  bits = 0;
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  for (rpos = 0; rpos < l; rpos++) {
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    c = src[rpos];
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    if (c == '=') {
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      break;
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    }
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    if (c > 255 || !inalphabet[c]) {
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      return -1;
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    }
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    bits += decoder[c];
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    char_count++;
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    if (char_count < 4) {
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      bits <<= 6;
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    } else {
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      dest[wpos++] = bits >> 16;
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      dest[wpos++] = (bits >> 8) & 0xff;
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      dest[wpos++] = bits & 0xff;
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      bits = 0;
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      char_count = 0;
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    }
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  }
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  switch (char_count) {
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  case 1:
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    return -1;
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    break;
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  case 2:
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    dest[wpos++] = bits >> 10;
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    break;
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  case 3:
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    dest[wpos++] = bits >> 16;
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    dest[wpos++] = (bits >> 8) & 0xff;
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    break;
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  }
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  return wpos;
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}
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int base64encode(char *dest, const char *src, int l)
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{
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  int bits, c, char_count;
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  int rpos;
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  int wpos = 0;
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  char_count = 0;
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  bits = 0;
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  for (rpos = 0; rpos < l; rpos++) {
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    c = src[rpos];
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    bits += c;
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    char_count++;
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    if (char_count < 3) {
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      bits <<= 8;
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    } else {
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      dest[wpos++] = alphabet[bits >> 18];
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      dest[wpos++] = alphabet[(bits >> 12) & 0x3f];
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      dest[wpos++] = alphabet[(bits >> 6) & 0x3f];
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      dest[wpos++] = alphabet[bits & 0x3f];
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      bits = 0;
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      char_count = 0;
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    }
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  }
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  if (char_count != 0) {
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    bits <<= 16 - (8 * char_count);
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    dest[wpos++] = alphabet[bits >> 18];
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    dest[wpos++] = alphabet[(bits >> 12) & 0x3f];
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    if (char_count == 1) {
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      dest[wpos++] = '=';
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      dest[wpos++] = '=';
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    } else {
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      dest[wpos++] = alphabet[(bits >> 6) & 0x3f];
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      dest[wpos++] = '=';
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    }
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  }
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  return wpos;
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}
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