/*

 * Base64 encoding: Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>

 * This software may be distributed under the terms of the BSD license.

 *

 * Base64 decoding: Copyright (c) 2016, polfosol

 * Posted at https://stackoverflow.com/a/37109258 under the CC-BY-SA Creative

 * Commons license.

 */

#include "base64.h"

#include <open62541/types.h>

static const unsigned char base64_table[65] =

  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

unsigned char *

UA_base64(const unsigned char *src, size_t len, size_t *out_len) {

    if(len == 0) {

        *out_len = 0;

        return (unsigned char*)UA_EMPTY_ARRAY_SENTINEL;

    }

  size_t olen = 4*((len + 2) / 3); /* 3-byte blocks to 4-byte */

  if(olen < len)

    return NULL; /* integer overflow */

  unsigned char *out = (unsigned char*)UA_malloc(olen);

  if(!out)

    return NULL;

    *out_len = UA_base64_buf(src, len, out);

    return out;

}

size_t

UA_base64_buf(const unsigned char *src, size_t len, unsigned char *out) {

  const unsigned char *end = src + len;

  const unsigned char *in = src;

  unsigned char *pos = out;

  while(end - in >= 3) {

    *pos++ = base64_table[in[0] >> 2];

    *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];

    *pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];

    *pos++ = base64_table[in[2] & 0x3f];

    in += 3;

  }

  if(end - in) {

    *pos++ = base64_table[in[0] >> 2];

    if(end - in == 1) {

      *pos++ = base64_table[(in[0] & 0x03) << 4];

      *pos++ = '=';

    } else {

      *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];

      *pos++ = base64_table[(in[1] & 0x0f) << 2];

    }

    *pos++ = '=';

  }

    return (size_t)(pos - out);

}

static const uint32_t from_b64[256] = {

    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,

    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,

    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  62, 63, 62, 62, 63,

    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0,  0,  0,  0,  0,  0,

    0,  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, 0,  0,  0,  0,  63,

    0,  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};

unsigned char *

UA_unbase64(const unsigned char *src, size_t len, size_t *out_len) {

    // we need a minimum length

    if(len <= 2) {

        *out_len = 0;

        return (unsigned char*)UA_EMPTY_ARRAY_SENTINEL;

    }

    const unsigned char *p = src;

    size_t pad1 = len % 4 || p[len - 1] == '=';

    size_t pad2 = pad1 && (len % 4 > 2 || p[len - 2] != '=');

    const size_t last = (len - pad1) / 4 << 2;

    unsigned char *str = (unsigned char*)UA_malloc(last / 4 * 3 + pad1 + pad2);

    if(!str)

        return NULL;

    unsigned char *pos = str;

    for(size_t i = 0; i < last; i += 4) {

        uint32_t n = from_b64[p[i]] << 18 | from_b64[p[i + 1]] << 12 |

                     from_b64[p[i + 2]] << 6 | from_b64[p[i + 3]];

        *pos++ = (unsigned char)(n >> 16);

        *pos++ = (unsigned char)(n >> 8 & 0xFF);

        *pos++ = (unsigned char)(n & 0xFF);

    }

    if(pad1) {

        if (last + 1 >= len) {

            UA_free(str);

            *out_len = 0;

            return (unsigned char*)UA_EMPTY_ARRAY_SENTINEL;

        }

        uint32_t n = from_b64[p[last]] << 18 | from_b64[p[last + 1]] << 12;

        *pos++ = (unsigned char)(n >> 16);

        if(pad2) {

            if (last + 2 >= len) {

                UA_free(str);

                *out_len = 0;

                return (unsigned char*)UA_EMPTY_ARRAY_SENTINEL;

            }

            n |= from_b64[p[last + 2]] << 6;

            *pos++ = (unsigned char)(n >> 8 & 0xFF);

        }

    }

    *out_len = (uintptr_t)(pos - str);

    return str;

}