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src/subversion/subversion/libsvn_subr/base64.c  view on Meta::CPAN

  /* Encode a partial group at the end if necessary, and write it out.  */
  encode_partial_group(encoded, eb->buf, eb->buflen, eb->linelen, TRUE);
  enclen = encoded->len;
  if (enclen != 0)
    err = svn_stream_write(eb->output, encoded->data, &enclen);

  /* Pass on the close request and clean up the baton.  */
  if (err == SVN_NO_ERROR)
    err = svn_stream_close(eb->output);
  svn_pool_destroy(eb->scratch_pool);
  return err;
}


svn_stream_t *
svn_base64_encode(svn_stream_t *output, apr_pool_t *pool)
{
  struct encode_baton *eb = apr_palloc(pool, sizeof(*eb));
  svn_stream_t *stream;

  eb->output = output;
  eb->buflen = 0;
  eb->linelen = 0;
  eb->scratch_pool = svn_pool_create(pool);
  stream = svn_stream_create(eb, pool);
  svn_stream_set_write(stream, encode_data);
  svn_stream_set_close(stream, finish_encoding_data);
  return stream;
}


const svn_string_t *
svn_base64_encode_string2(const svn_string_t *str,
                          svn_boolean_t break_lines,
                          apr_pool_t *pool)
{
  svn_stringbuf_t *encoded = svn_stringbuf_create_empty(pool);
  unsigned char ingroup[3];
  size_t ingrouplen = 0;
  size_t linelen = 0;

  encode_bytes(encoded, str->data, str->len, ingroup, &ingrouplen, &linelen,
               break_lines);
  encode_partial_group(encoded, ingroup, ingrouplen, linelen,
                       break_lines);
  return svn_stringbuf__morph_into_string(encoded);
}

const svn_string_t *
svn_base64_encode_string(const svn_string_t *str, apr_pool_t *pool)
{
  return svn_base64_encode_string2(str, TRUE, pool);
}



/* Base64-encoded input --> binary output */

struct decode_baton {
  svn_stream_t *output;
  unsigned char buf[4];         /* Bytes waiting to be decoded */
  int buflen;                   /* Number of bytes waiting */
  svn_boolean_t done;           /* True if we already saw an '=' */
  apr_pool_t *scratch_pool;
};


/* Base64-decode a group.  IN needs to have four bytes and OUT needs
   to have room for three bytes.  The input bytes must already have
   been decoded from base64tab into the range 0..63.  The four
   six-bit values are pasted together to form three eight-bit bytes.  */
static APR_INLINE void
decode_group(const unsigned char *in, char *out)
{
  out[0] = (char)((in[0] << 2) | (in[1] >> 4));
  out[1] = (char)(((in[1] & 0xf) << 4) | (in[2] >> 2));
  out[2] = (char)(((in[2] & 0x3) << 6) | in[3]);
}

/* Lookup table for base64 characters; reverse_base64[ch] gives a
   negative value if ch is not a valid base64 character, or otherwise
   the value of the byte represented; 'A' => 0 etc. */
static const signed char reverse_base64[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};

/* Similar to decode_group but this function also translates the
   6-bit values from the IN buffer before translating them.
   Return FALSE if a non-base64 char (e.g. '=' or new line)
   has been encountered. */
static APR_INLINE svn_boolean_t
decode_group_directly(const unsigned char *in, char *out)
{
  /* Translate the base64 chars in values [0..63, 0xff] */
  apr_size_t part0 = (unsigned char)reverse_base64[(unsigned char)in[0]];
  apr_size_t part1 = (unsigned char)reverse_base64[(unsigned char)in[1]];
  apr_size_t part2 = (unsigned char)reverse_base64[(unsigned char)in[2]];
  apr_size_t part3 = (unsigned char)reverse_base64[(unsigned char)in[3]];

  /* Pack 4x6 bits into 3x8.*/
  out[0] = (char)((part0 << 2) | (part1 >> 4));
  out[1] = (char)(((part1 & 0xf) << 4) | (part2 >> 2));
  out[2] = (char)(((part2 & 0x3) << 6) | part3);

  /* FALSE, iff any part is 0xff. */
  return (part0 | part1 | part2 | part3) != (unsigned char)(-1);
}

/* Base64-encode up to BASE64_LINELEN chars from *DATA and append it to
   STR.  After the function returns, *DATA will point to the first char
   that has not been translated, yet.  Returns TRUE if all BASE64_LINELEN
   chars could be translated, i.e. no special char has been encountered
   in between.
   The code in this function will simply transform the data without
   performing any boundary checks.  Therefore, DATA must have at least
   BASE64_LINELEN left and space for at least another BYTES_PER_LINE
   chars must have been pre-allocated in STR before calling this
   function. */
static svn_boolean_t
decode_line(svn_stringbuf_t *str, const char **data)
{
  /* Decode up to BYTES_PER_LINE bytes directly from *DATA into STR->DATA. */
  const unsigned char *p = *(const unsigned char **)data;
  char *out = str->data + str->len;
  char *end = out + BYTES_PER_LINE;

  /* We assume that BYTES_PER_LINE is a multiple of 3 and BASE64_LINELEN
     a multiple of 4.  Stop translation as soon as we encounter a special
     char.  Leave the entire group untouched in that case. */
  for (; out < end; p += 4, out += 3)
    if (!decode_group_directly(p, out))
      break;

  /* Update string sizes and positions. */
  str->len = out - str->data;
  *out = '\0';
  *data = (const char *)p;

  /* Return FALSE, if the caller should continue the decoding process
     using the slow standard method. */
  return out == end;
}


/* (Continue to) Base64-decode the byte string DATA (of length LEN)
   into STR. INBUF, INBUFLEN, and DONE are used internally; the
   caller shall have room for four bytes in INBUF and initialize
   *INBUFLEN to 0 and *DONE to FALSE.

   INBUF and *INBUFLEN carry the leftover bytes from call to call, and
   *DONE keeps track of whether we've seen an '=' which terminates the
   encoded data. */
static void
decode_bytes(svn_stringbuf_t *str, const char *data, apr_size_t len,
             unsigned char *inbuf, int *inbuflen, svn_boolean_t *done)
{
  const char *p = data;
  char group[3];
  signed char find;
  const char *end = data + len;

  /* Resize the stringbuf to make room for the maximum size of output,
     to avoid repeated resizes later.  The optimizations in
     decode_line rely on no resizes being necessary!

     (*inbuflen+len) is encoded data length
     (*inbuflen+len)/4 is the number of complete 4-bytes sets
     (*inbuflen+len)/4*3 is the number of decoded bytes
     svn_stringbuf_ensure will add an additional byte for the terminating 0.
  */
  svn_stringbuf_ensure(str, str->len + ((*inbuflen + len) / 4) * 3);

  while ( !*done && p < end )
    {
      /* If no data is left in temporary INBUF and there is at least
         one line-sized chunk left to decode, we may use the optimized
         code path. */
      if ((*inbuflen == 0) && (p + BASE64_LINELEN <= end))
        if (decode_line(str, &p))
          continue;

      /* A special case or decode_line encountered a special char. */
      if (*p == '=')
        {
          /* We are at the end and have to decode a partial group.  */
          if (*inbuflen >= 2)
            {
              memset(inbuf + *inbuflen, 0, 4 - *inbuflen);
              decode_group(inbuf, group);
              svn_stringbuf_appendbytes(str, group, *inbuflen - 1);
            }
          *done = TRUE;
        }
      else
        {
          find = reverse_base64[(unsigned char)*p];
          ++p;

          if (find >= 0)
            inbuf[(*inbuflen)++] = find;
          if (*inbuflen == 4)
            {
              decode_group(inbuf, group);
              svn_stringbuf_appendbytes(str, group, 3);
              *inbuflen = 0;
            }
        }
    }
}


/* Write handler for svn_base64_decode.  */
static svn_error_t *
decode_data(void *baton, const char *data, apr_size_t *len)
{
  struct decode_baton *db = baton;
  svn_stringbuf_t *decoded;
  apr_size_t declen;
  svn_error_t *err = SVN_NO_ERROR;

  /* Decode this block of data.  */
  decoded = svn_stringbuf_create_empty(db->scratch_pool);
  decode_bytes(decoded, data, *len, db->buf, &db->buflen, &db->done);

  /* Write the output, clean up, go home.  */
  declen = decoded->len;
  if (declen != 0)
    err = svn_stream_write(db->output, decoded->data, &declen);
  svn_pool_clear(db->scratch_pool);
  return err;
}


/* Close handler for svn_base64_decode().  */
static svn_error_t *
finish_decoding_data(void *baton)
{
  struct decode_baton *db = baton;
  svn_error_t *err;

  /* Pass on the close request and clean up the baton.  */
  err = svn_stream_close(db->output);
  svn_pool_destroy(db->scratch_pool);
  return err;
}


svn_stream_t *
svn_base64_decode(svn_stream_t *output, apr_pool_t *pool)
{
  struct decode_baton *db = apr_palloc(pool, sizeof(*db));
  svn_stream_t *stream;

  db->output = output;
  db->buflen = 0;
  db->done = FALSE;
  db->scratch_pool = svn_pool_create(pool);
  stream = svn_stream_create(db, pool);
  svn_stream_set_write(stream, decode_data);
  svn_stream_set_close(stream, finish_decoding_data);
  return stream;
}


const svn_string_t *
svn_base64_decode_string(const svn_string_t *str, apr_pool_t *pool)
{
  svn_stringbuf_t *decoded = svn_stringbuf_create_empty(pool);
  unsigned char ingroup[4];
  int ingrouplen = 0;
  svn_boolean_t done = FALSE;

  decode_bytes(decoded, str->data, str->len, ingroup, &ingrouplen, &done);
  return svn_stringbuf__morph_into_string(decoded);
}


/* Return a base64-encoded representation of CHECKSUM, allocated in POOL.
   If CHECKSUM->kind is not recognized, return NULL.
   ### That 'NULL' claim was in the header file when this was public, but
   doesn't look true in the implementation.

   ### This is now only used as a new implementation of svn_base64_from_md5();
   it would probably be safer to revert that to its old implementation. */
static svn_stringbuf_t *
base64_from_checksum(const svn_checksum_t *checksum, apr_pool_t *pool)
{
  svn_stringbuf_t *checksum_str;
  unsigned char ingroup[3];
  size_t ingrouplen = 0;
  size_t linelen = 0;
  checksum_str = svn_stringbuf_create_empty(pool);

  encode_bytes(checksum_str, checksum->digest,
               svn_checksum_size(checksum), ingroup, &ingrouplen,
               &linelen, TRUE);
  encode_partial_group(checksum_str, ingroup, ingrouplen, linelen, TRUE);

  /* Our base64-encoding routines append a final newline if any data
     was created at all, so let's hack that off. */
  if (checksum_str->len)
    {
      checksum_str->len--;
      checksum_str->data[checksum_str->len] = 0;
    }

  return checksum_str;
}


svn_stringbuf_t *
svn_base64_from_md5(unsigned char digest[], apr_pool_t *pool)
{
  svn_checksum_t *checksum
    = svn_checksum__from_digest_md5(digest, pool);

  return base64_from_checksum(checksum, pool);
}