tbase64.c

/**
 * Copyright (c) 2006-2008 Apple Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

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

// deprecated this file for bug prone
// base64 encode
static char basis_64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char *base64_encode(const unsigned char *value, int vlen) {
  unsigned char oval = 0;
  char *        result = (char *)malloc((size_t)(vlen * 4) / 3 + 10);
  char *        out = result;
  while (vlen >= 3) {
    *out++ = basis_64[value[0] >> 2];
    *out++ = basis_64[((value[0] << 4) & 0x30) | (value[1] >> 4)];
    *out++ = basis_64[((value[1] << 2) & 0x3C) | (value[2] >> 6)];
    *out++ = basis_64[value[2] & 0x3F];
    value += 3;
    vlen -= 3;
  }
  if (vlen > 0) {
    *out++ = basis_64[value[0] >> 2];
    oval = (value[0] << 4) & 0x30;
    if (vlen > 1) oval |= value[1] >> 4;
    *out++ = basis_64[oval];
    *out++ = (vlen < 2) ? '=' : basis_64[(value[1] << 2) & 0x3C];
    *out++ = '=';
  }
  *out = '\0';
  return result;
}

// base64 decode
#define CHAR64(c) (((c) < 0 || (c) > 127) ? -1 : index_64[(c)])
static signed char index_64[128] = {
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55,
    56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 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, -1, -1, -1, -1, -1, -1, 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, -1, -1, -1, -1, -1};

unsigned char *base64_decode(const char *value, int inlen, int *outlen) {
  int            c1, c2, c3, c4;
  unsigned char *result = (unsigned char *)malloc((size_t)(inlen * 3) / 4 + 1);
  unsigned char *out = result;

  *outlen = 0;

  while (1) {
    if (value[0] == 0) {
      *out = '\0';
      return result;
    }

    // skip \r\n
    if (value[0] == '\n' || value[0] == '\r') {
      value += 1;
      continue;
    }

    c1 = value[0];
    if (CHAR64(c1) == -1) goto base64_decode_error;
    c2 = value[1];
    if (CHAR64(c2) == -1) goto base64_decode_error;
    c3 = value[2];
    if ((c3 != '=') && (CHAR64(c3) == -1)) goto base64_decode_error;
    c4 = value[3];
    if ((c4 != '=') && (CHAR64(c4) == -1)) goto base64_decode_error;

    value += 4;
    *out++ = (unsigned char)((CHAR64(c1) << 2) | (CHAR64(c2) >> 4));
    *outlen += 1;
    if (c3 != '=') {
      *out++ = (unsigned char)(((CHAR64(c2) << 4) & 0xf0) | (CHAR64(c3) >> 2));
      *outlen += 1;
      if (c4 != '=') {
        *out++ = (unsigned char)(((CHAR64(c3) << 6) & 0xc0) | CHAR64(c4));
        *outlen += 1;
      }
    }
  }

base64_decode_error:
  free(result);
  *result = 0;
  *outlen = 0;

  return result;
}