pcp/include/pcp/z85.h

/*
    This file is part of Pretty Curved Privacy (pcp1).

    Copyright (C) 2013-2014 T.v.Dein.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

    You can contact me by mail: <tom AT vondein DOT org>.
*/


/*  from https://github.com/tlinden/curve-keygen/ */
#ifndef _HAVE_PCP_Z85_H

/**
 * \defgroup Z85 Z85
 * @{

 Z85 Encoding functions.

The Z85 encoding format is described here: <a href="http://rfc.zeromq.org/spec:32">ZeroMQ Spec.32</a>.
It's part of <a href="http://zeromq.org">ZeroMQ</a>. Z85 is based on ASCII85 with
a couple of modifications (portability, readability etc).

To fulfil the requirements of the ZeroMQ Z85 functions, PCP
does some additional preparations of raw input before actually doing the 
encoding, since the input for zmq_z85_encode() must be divisible by 4. Therefore
we pad the input with zeroes and remove them after decoding.

 */
#include <ctype.h>
#include "defines.h"
#include "zmq_z85.h"
#include "mem.h"
#include "buffer.h"

/** Zero-pad some input data.

    This function allocates new memory for the returned data. It puts
    the original pointer into it and adds a number of zeros so that the
    result has a size divisable by 4.

    \param[in] src Unpadded data.
    \param[in] srclen Size of unpadded data.
    \param[in] dstlen Returned size of padded data (pointer to int).

    \return Returns a pointer to the padded data.
 */
byte *pcp_padfour(byte *src, size_t srclen, size_t *dstlen);


/** Unpad padded input data.

    It just calculates the size of the unpadded result (size - all trailing zeroes).
    Doesn't allocate any memory or modify anything.

    \param[in] src Padded data.
    \param[in] srclen Size of padded data.

    \return Returns the unpadded size of the data.
 */
size_t pcp_unpadfour(byte *src, size_t srclen);

/** Decode data from Z85 encoding.

    The input \a z85block may contain newlines which will be removed.

    \param[in] z85block The Z85 encoded string.
    \param[in] dstlen Returned size of decoded data (pointer to int).

    \return Returns a newly allocated pointer to the decoded data. If decoding failed,
            returns NULL. Check fatals_if_any().

*/
byte *pcp_z85_decode(char *z85block, size_t *dstlen);


/** Encode data to Z85 encoding.

    Beside Z85 encoding it also adds a newline everiy 72 characters.

    \param[in] raw Pointer to raw data.
    \param[in] srclen Size of the data.
    \param[in] dstlen Returned size of encoded data (pointer to int).

    \return Returns a string (char array) containing the Z85 encoded data.
*/
char *pcp_z85_encode(byte *raw, size_t srclen, size_t *dstlen);

/** Read a Z85 encoded file.

    Reads a file and returns the raw Z85 encoded string.
    It ignores newlines, comments and Headerstrings.

    \param[in] infile FILE stream to read from.

    \return Raw Z85 encoded string with comments, headers and newlines removed.
 */
char *pcp_readz85file(FILE *infile);

/** Read a Z85 encoded string.

    Parses the given input string and returns the raw Z85 encoded string.
    It ignores newlines, comments and Headerstrings.

    \param[in] input Z85 encoded string.
    \param[in] bufsize Size of the string.

    \return Raw Z85 encoded string with comments, headers and newlines removed.

 */
char *pcp_readz85string(byte *input, size_t bufsize);

/** Check if a binary array is utf8.

    Based on http://stackoverflow.com/questions/1031645/how-to-detect-utf-8-in-plain-c
    by Christoph Gärtner

    Modified to only check for one utf8 char. The given sequence must have
    at least 4 bytes length. No boundary checks are being made.

    \param[in] bytes A byte sequence with 4 or more bytes length.

    \return Returns 0 if the sequence is not utf8 or a number greater than 1 indicating the size of the utf8 char.
*/
uint8_t is_utf8(const byte * bytes);

/** Determine if a buffer is binary or ascii.

    \param[in] buf The buffer to check.
    \param[in] len Len of the buffer.
    \return Returns 0 if the input is ascii or a number > 0 if
            it contains binary data.
*/
size_t _buffer_is_binary(byte *buf, size_t len);


/** Determine if a char is a Z85 character

    \param[out] z Buffer object where to put the char if it's z85 and not inside a comment.
    \param[in] c The char to check.
    \param[in] is_comment Denotes if we're currently within a comment.

    \return Returns 1 if a comment starts or 0 otherwise.
 */
uint8_t _parse_zchar(Buffer *z, uint8_t c, uint8_t is_comment);


long int z85_header_startswith(Buffer *buf, char *what);
int z85_isheader(Buffer *buf);
int z85_isend(Buffer *buf);
int z85_isbegin(Buffer *buf);
int z85_iscomment(Buffer *buf);
int z85_isempty(Buffer *line);
int z85_isencoded(Buffer *line);

#endif /*  _HAVE_PCP_Z85_H */

/**@}*/