/*
 * Base64 encoding/decoding (RFC1341)
 * Copyright (c) 2005, Jouni Malinen <jkmaline@cc.hut.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include <stdlib.h>
#include <string.h>

#include "base64.h"

static const unsigned char base64_table[64] =
    "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, int len,
                             int *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 / 72; /* line feeds */
    olen++; /* nul termination */
    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 >= 72) {
            //*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, int len,
                             int *out_len)
{
    unsigned char dtable[256], *out, *pos, in[4], block[4], tmp;
    size_t i, count;

    memset(dtable, 0x80, 256);
    for (i = 0; i < sizeof(base64_table); i++) {
        dtable[base64_table[i]] = i;
    }
    dtable['='] = 0;

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

    if (count % 4) {
        return NULL;
    }

    pos = out = malloc(count);
    if (out == NULL) {
        return NULL;
    }

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

        in[count] = src[i];
        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 (pos > out) {
        if (in[2] == '=') {
            pos -= 2;
        } else if (in[3] == '=') {
            pos--;
        }
    }

    *out_len = pos - out;
    return out;
}


/* #ifdef TEST_MAIN */
/* #include <stdio.h> */

/* int main(int argc, char *argv[]) */
/* { */
/* FILE *f; */
/* size_t len, elen; */
/* unsigned char *buf, *e; */

/* if (argc != 4) { */
/* printf("Usage: base64 <encode|decode> <in file> <out file>\n"); */
/* return -1; */
/* } */

/* f = fopen(argv[2], "r"); */
/* if (f == NULL) */
/* return -1; */
/* fseek(f, 0, SEEK_END); */
/* len = ftell(f); */
/* fseek(f, 0, SEEK_SET); */
/* buf = malloc(len); */
/* if (buf == NULL) { */
/* fclose(f); */
/* return -1; */
/* } */
/* fread(buf, 1, len, f); */
/* fclose(f); */

/* if (strcmp(argv[1], "encode") == 0) */
/* e = base64_encode(buf, len, &elen); */
/* else */
/* e = base64_decode(buf, len, &elen); */
/* if (e == NULL) */
/* return -2; */
/* f = fopen(argv[3], "w"); */
/* if (f == NULL) */
/* return -3; */
/* fwrite(e, 1, elen, f); */
/* fclose(f); */
/* free(e); */

/* return 0; */
/* } */
/* #endif [> TEST_MAIN <] */