Function xpack_decode_string

src/proxy/hdrs/XPACK.cc:98–138

[RFC 7541] 5.2. String Literal Representation return content from String Data (Length octets) with huffman decoding if it is encoded

// return content from String Data (Length octets) with huffman decoding if it is encoded
//
int64_t
xpack_decode_string(Arena &arena, char **str, uint64_t &str_length, const uint8_t *buf_start, const uint8_t *buf_end, uint8_t n)
{
  if (buf_start >= buf_end) {
    return XPACK_ERROR_COMPRESSION_ERROR;
  }

  const uint8_t *p                  = buf_start;
  bool           isHuffman          = *p & (0x01 << n);
  uint64_t       encoded_string_len = 0;
  int64_t        len                = 0;

  len = xpack_decode_integer(encoded_string_len, p, buf_end, n);
  if (len == XPACK_ERROR_COMPRESSION_ERROR) {
    return XPACK_ERROR_COMPRESSION_ERROR;
  }
  p += len;

  if (buf_end < p || static_cast<uint64_t>(buf_end - p) < encoded_string_len) {
    return XPACK_ERROR_COMPRESSION_ERROR;
  }

  if (isHuffman) {
    // Allocate temporary area twice the size of before decoded data
    *str = arena.str_alloc(encoded_string_len * 2);

    len = huffman_decode(*str, p, encoded_string_len);
    if (len < 0) {
      return XPACK_ERROR_COMPRESSION_ERROR;
    }
    str_length = len;
  } else {
    *str = arena.str_alloc(encoded_string_len);

    memcpy(*str, reinterpret_cast<const char *>(p), encoded_string_len);

    str_length = encoded_string_len;
  }

  return p + encoded_string_len - buf_start;
}

//
// [RFC 7541] 5.1. Integer representation