/*

 * Copyright (c) 2006 Ryan Martell. (rdm4@martellventures.com)

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * @brief Base64 encode/decode

 * @author Ryan Martell <rdm4@martellventures.com> (with lots of Michael)

 */

#include <limits.h>

#include <stddef.h>

#include "base64.h"

#include "error.h"

#include "intreadwrite.h"

/* ---------------- private code */

static const uint8_t map2[256] =

{

    0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff,

    0x3e, 0xff, 0xff, 0xff, 0x3f, 0x34, 0x35, 0x36,

    0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0xff,

    0xff, 0xff, 0xfe, 0xff, 0xff, 0xff, 0x00, 0x01,

    0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,

    0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11,

    0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1a, 0x1b,

    0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,

    0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,

    0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33,

                      0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

};

#define BASE64_DEC_STEP(i) do { \

    bits = map2[in[i]]; \

    if (bits & 0x80) \

        goto out ## i; \

    v = i ? (v << 6) + bits : bits; \

} while(0)

int av_base64_decode(uint8_t *out, const char *in_str, int out_size)

{

    uint8_t *dst = out;

    uint8_t *end;

    // no sign extension

    const uint8_t *in = in_str;

    unsigned bits = 0xff;

    unsigned v;

    if (!out)

        goto validity_check;

    end = out + out_size;

    while (end - dst > 3) {

        BASE64_DEC_STEP(0);

        BASE64_DEC_STEP(1);

        BASE64_DEC_STEP(2);

        BASE64_DEC_STEP(3);

        // Using AV_WB32 directly confuses compiler

        v = av_be2ne32(v << 8);

        AV_WN32(dst, v);

        dst += 3;

        in += 4;

    }

    if (end - dst) {

        BASE64_DEC_STEP(0);

        BASE64_DEC_STEP(1);

        BASE64_DEC_STEP(2);

        BASE64_DEC_STEP(3);

        *dst++ = v >> 16;

        if (end - dst)

            *dst++ = v >> 8;

        if (end - dst)

            *dst++ = v;

        in += 4;

    }

validity_check:

    while (1) {

        BASE64_DEC_STEP(0);

        in++;

        BASE64_DEC_STEP(0);

        in++;

        BASE64_DEC_STEP(0);

        in++;

        BASE64_DEC_STEP(0);

        in++;

    }

out3:

    if (end - dst)

        *dst++ = v >> 10;

    v <<= 2;

out2:

    if (end - dst)

        *dst++ = v >> 4;

out1:

out0:

    return bits & 1 ? AVERROR_INVALIDDATA : out ? dst - out : 0;

}

/*****************************************************************************

* b64_encode: Stolen from VLC's http.c.

* Simplified by Michael.

* Fixed edge cases and made it work from data (vs. strings) by Ryan.

*****************************************************************************/

char *av_base64_encode(char *out, int out_size, const uint8_t *in, int in_size)

{

    static const char b64[] =

        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    char *ret, *dst;

    unsigned i_bits = 0;

    int i_shift = 0;

    int bytes_remaining = in_size;

    if (in_size >= UINT_MAX / 4 ||

        out_size < AV_BASE64_SIZE(in_size))

        return NULL;

    ret = dst = out;

    while (bytes_remaining > 3) {

        i_bits = AV_RB32(in);

        in += 3; bytes_remaining -= 3;

        *dst++ = b64[ i_bits>>26        ];

        *dst++ = b64[(i_bits>>20) & 0x3F];

        *dst++ = b64[(i_bits>>14) & 0x3F];

        *dst++ = b64[(i_bits>>8 ) & 0x3F];

    }

    i_bits = 0;

    while (bytes_remaining) {

        i_bits = (i_bits << 8) + *in++;

        bytes_remaining--;

        i_shift += 8;

    }

    while (i_shift > 0) {

        *dst++ = b64[(i_bits << 6 >> i_shift) & 0x3f];

        i_shift -= 6;

    }

    while ((dst - ret) & 3)

        *dst++ = '=';

    *dst = '\0';

    return ret;

}