/*
 * Base64 encoding/decoding (RFC1341)
 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "base64.h"

static const unsigned char base64_table[65] =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**
 * base64_encode - Base64 encode
 * @src: Data to be encoded
 * @len: Length of the data to be encoded
 * @out_len: Pointer to output length variable, or %NULL if not used
 * Returns: Allocated buffer of out_len bytes of encoded data,
 * or %NULL on failure
 *
 * Caller is responsible for freeing the returned buffer. Returned buffer is
 * nul terminated to make it easier to use as a C string. The nul terminator is
 * not included in out_len.
 */
unsigned char * base64_encode(const unsigned char *src, size_t len,
			      size_t *out_len)
{
	unsigned char *out, *pos;
	const unsigned char *end, *in;
	size_t olen;
	int line_len;

	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
	olen += olen / 76; /* line feeds */
	olen++; /* nul termination */
	if (olen < len)
		return NULL; /* integer overflow */
	out = malloc(olen);
	if (out == NULL)
		return NULL;

	end = src + len;
	in = src;
	pos = out;
	line_len = 0;
	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;
		line_len += 4;
		if (line_len >= 76) {
			*pos++ = '\n';
			line_len = 0;
		}
	}

	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++ = '=';
		line_len += 4;
	}

	if (line_len)
		*pos++ = '\n';

	*pos = '\0';
	if (out_len)
		*out_len = pos - out;
	return out;
}


/**
 * base64_decode - Base64 decode
 * @src: Data to be decoded
 * @len: Length of the data to be decoded
 * @out_len: Pointer to output length variable
 * Returns: Allocated buffer of out_len bytes of decoded data,
 * or %NULL on failure
 *
 * Caller is responsible for freeing the returned buffer.
 */
unsigned char * base64_decode(const unsigned char *src, size_t len,
			      size_t *out_len)
{
	unsigned char dtable[256], *out, *pos, block[4], tmp;
	size_t i, count, olen;
	int pad = 0;

	memset(dtable, 0x80, 256);
	for (i = 0; i < sizeof(base64_table) - 1; i++)
		dtable[base64_table[i]] = (unsigned char) i;
	dtable['='] = 0;

	count = 0;
	for (i = 0; i < len; i++) {
		if (dtable[src[i]] != 0x80)
			count++;
	}

	if (count == 0 || count % 4)
		return NULL;

	olen = count / 4 * 3;
	pos = out = malloc(olen);
	if (out == NULL)
		return NULL;

	count = 0;
	for (i = 0; i < len; i++) {
		tmp = dtable[src[i]];
		if (tmp == 0x80)
			continue;

		if (src[i] == '=')
			pad++;
		block[count] = tmp;
		count++;
		if (count == 4) {
			*pos++ = (block[0] << 2) | (block[1] >> 4);
			*pos++ = (block[1] << 4) | (block[2] >> 2);
			*pos++ = (block[2] << 6) | block[3];
			count = 0;
			if (pad) {
				if (pad == 1)
					pos--;
				else if (pad == 2)
					pos -= 2;
				else {
					/* Invalid padding */
					free(out);
					return NULL;
				}
				break;
			}
		}
	}

	*out_len = pos - out;
	return out;
}

unsigned char * b64t_encode(const unsigned char *src, size_t len,
            			      size_t *out_len)
{
    // allocate new buffer
    unsigned char *out = malloc(len);
    if (out == NULL)
        return NULL;
    memset(out, 0, len);
    
    // remove new line
    size_t index = 0;
    size_t new_index = 0;
    for (index =0; index < len; index++)
    {
        if(src[index] != '\n' && 
           src[index] != '\r' &&
           src[index] != '='  && 
           src[index] >= '+'  &&
           src[index] <= 'z'     ) {
            out[new_index] = src[index];
            new_index ++;
        }
    }
    if(new_index)
        out[new_index] = 0;
    *out_len = new_index;

    for (size_t i=0; i < *out_len; i++) {
        if(out[i] == '+') {
            out[i] = '-';
        }
    }
    for (size_t i=0; i < *out_len; i++) {
        if(out[i] == '/') {
            out[i] = '_';
        }
    }
    return out;
}

unsigned char * b64t_decode(const unsigned char *src, size_t len,
            			      size_t *out_len)
{
    size_t index = 0;
    size_t nb_encoding_chars = 0;
    for (index=0; index < len; index++) {
        if(src[index] == '\n' ||
           src[index] == '\r' || 
           src[index] == '=') {
            nb_encoding_chars++;
        }
    }

    size_t new_len = len - nb_encoding_chars;
    size_t nb_newlines = new_len / 76;
    size_t padding_len = 0;
    if (new_len % 4 != 0) {
        padding_len = 4 - new_len % 4;
    }
    *out_len = new_len + nb_newlines + padding_len + 1;

    // allocate new buffer
    unsigned char *out = malloc(*out_len);
    if (out == NULL)
        return NULL;
    memset(out, 0, len);

    size_t index_out = 0;
    size_t index_data = 0;
    for(index = 0; index < len; index++) {
        if(src[index] != '\n' &&
           src[index] != '\r' &&
           src[index] != '=') {
            if(index_data != 0 && index_data % 76 == 0) {
                out[index_out] = '\n';
                index_out++;
            }
            if (src[index] == '-') {
                out[index_out] = '+';
            }
            else if (src[index] == '_') {
                out[index_out] = '/';
            }
            else {
                out[index_out] = src[index];
            }
            index_out++;
            index_data++;
        }
    }
    for(index = 0; index < padding_len; index ++) {
        out[index_out] = '=';
        index_out++;
    }
    out[index_out] = '\n';

    return out;
}