include/openssl/base64.h

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#ifndef OPENSSL_HEADER_BASE64_H
#define OPENSSL_HEADER_BASE64_H

#include <openssl/base.h>

#if defined(__cplusplus)
extern "C" {
#endif


// base64 functions.
//
// For historical reasons, these functions have the EVP_ prefix but just do
// base64 encoding and decoding. Note that BoringSSL is a cryptography library,
// so these functions are implemented with side channel protections, at a
// performance cost. For other base64 uses, use a general-purpose base64
// implementation.


// Encoding

// EVP_EncodeBlock encodes |src_len| bytes from |src| and writes the
// result to |dst| with a trailing NUL. It returns the number of bytes
// written, not including this trailing NUL.
OPENSSL_EXPORT size_t EVP_EncodeBlock(uint8_t *dst, const uint8_t *src,
                                      size_t src_len);

// EVP_EncodedLength sets |*out_len| to the number of bytes that will be needed
// to call |EVP_EncodeBlock| on an input of length |len|. This includes the
// final NUL that |EVP_EncodeBlock| writes. It returns one on success or zero
// on error.
OPENSSL_EXPORT int EVP_EncodedLength(size_t *out_len, size_t len);


// Decoding

// EVP_DecodedLength sets |*out_len| to the maximum number of bytes that will
// be needed to call |EVP_DecodeBase64| on an input of length |len|. It returns
// one on success or zero if |len| is not a valid length for a base64-encoded
// string.
OPENSSL_EXPORT int EVP_DecodedLength(size_t *out_len, size_t len);

// EVP_DecodeBase64 decodes |in_len| bytes from base64 and writes
// |*out_len| bytes to |out|. |max_out| is the size of the output
// buffer. If it is not enough for the maximum output size, the
// operation fails. It returns one on success or zero on error.
OPENSSL_EXPORT int EVP_DecodeBase64(uint8_t *out, size_t *out_len,
                                    size_t max_out, const uint8_t *in,
                                    size_t in_len);


// Deprecated functions.
//
// OpenSSL provides a streaming base64 implementation, however its behavior is
// very specific to PEM. It is also very lenient of invalid input. Use of any of
// these functions is thus deprecated.

// EVP_EncodeInit initialises |*ctx|, which is typically stack
// allocated, for an encoding operation.
//
// NOTE: The encoding operation breaks its output with newlines every
// 64 characters of output (48 characters of input). Use
// EVP_EncodeBlock to encode raw base64.
OPENSSL_EXPORT void EVP_EncodeInit(EVP_ENCODE_CTX *ctx);

// EVP_EncodeUpdate encodes |in_len| bytes from |in| and writes an encoded
// version of them to |out| and sets |*out_len| to the number of bytes written.
// Some state may be contained in |ctx| so |EVP_EncodeFinal| must be used to
// flush it before using the encoded data.
OPENSSL_EXPORT void EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, uint8_t *out,
                                     int *out_len, const uint8_t *in,
                                     size_t in_len);

// EVP_EncodeFinal flushes any remaining output bytes from |ctx| to |out| and
// sets |*out_len| to the number of bytes written.
OPENSSL_EXPORT void EVP_EncodeFinal(EVP_ENCODE_CTX *ctx, uint8_t *out,
                                    int *out_len);

// EVP_DecodeInit initialises |*ctx|, which is typically stack allocated, for
// a decoding operation.
//
// TODO(davidben): This isn't a straight-up base64 decode either. Document
// and/or fix exactly what's going on here; maximum line length and such.
OPENSSL_EXPORT void EVP_DecodeInit(EVP_ENCODE_CTX *ctx);

// EVP_DecodeUpdate decodes |in_len| bytes from |in| and writes the decoded
// data to |out| and sets |*out_len| to the number of bytes written. Some state
// may be contained in |ctx| so |EVP_DecodeFinal| must be used to flush it
// before using the encoded data.
//
// It returns -1 on error, one if a full line of input was processed and zero
// if the line was short (i.e. it was the last line).
OPENSSL_EXPORT int EVP_DecodeUpdate(EVP_ENCODE_CTX *ctx, uint8_t *out,
                                    int *out_len, const uint8_t *in,
                                    size_t in_len);

// EVP_DecodeFinal flushes any remaining output bytes from |ctx| to |out| and
// sets |*out_len| to the number of bytes written. It returns one on success
// and minus one on error.
OPENSSL_EXPORT int EVP_DecodeFinal(EVP_ENCODE_CTX *ctx, uint8_t *out,
                                   int *out_len);

// EVP_DecodeBlock encodes |src_len| bytes from |src| and writes the result to
// |dst|. It returns the number of bytes written or -1 on error.
//
// WARNING: EVP_DecodeBlock's return value does not take padding into
// account. It also strips leading whitespace and trailing
// whitespace and minuses.
OPENSSL_EXPORT int EVP_DecodeBlock(uint8_t *dst, const uint8_t *src,
                                   size_t src_len);


struct evp_encode_ctx_st {
  // data_used indicates the number of bytes of |data| that are valid. When
  // encoding, |data| will be filled and encoded as a lump. When decoding, only
  // the first four bytes of |data| will be used.
  unsigned data_used;
  uint8_t data[48];

  // eof_seen indicates that the end of the base64 data has been seen when
  // decoding. Only whitespace can follow.
  char eof_seen;

  // error_encountered indicates that invalid base64 data was found. This will
  // cause all future calls to fail.
  char error_encountered;
};


#if defined(__cplusplus)
}  // extern C
#endif

#endif  // OPENSSL_HEADER_BASE64_H