1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <objmng/drm_decoder.h>
18
19/* global variables */
20static const uint8_t * base64_alphabet = (const uint8_t *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
21
22#define SKIP_CRLF(p) while('\r' == *(p) || '\n' == *(p)) \
23                         p++
24
25static int8_t get_alphabet_index(int8_t ch)
26{
27    uint8_t * tmp;
28
29    if ('=' == ch)
30        return 64;
31
32    tmp = (uint8_t *)strchr((const char *)base64_alphabet, ch);
33    if (NULL == tmp)
34        return -1;
35
36    return (int8_t)(tmp - base64_alphabet);
37}
38
39/* See drm_decoder.h */
40int32_t drm_decodeBase64(uint8_t * dest, int32_t destLen, uint8_t * src, int32_t * srcLen)
41{
42    int32_t maxDestSize, i, maxGroup;
43    uint8_t *pDest, *pSrc;
44    int8_t tpChar;
45
46    if (NULL == src || NULL == srcLen || *srcLen <= 0 || destLen < 0)
47        return -1;
48
49    maxDestSize = (*srcLen) * 3/4;
50    if (NULL == dest || 0 == destLen)
51        return maxDestSize;
52
53    if (destLen < maxDestSize)
54        maxDestSize = destLen;
55    maxGroup = maxDestSize/3;
56
57    pDest = dest;   /* start to decode src to dest */
58    pSrc = src;
59    for (i = 0; i < maxGroup && *srcLen - (pSrc - src) >= 4; i++) {
60        SKIP_CRLF(pSrc);
61        if (pSrc - src >= *srcLen)
62            break;
63        tpChar = get_alphabet_index(*pSrc);       /* to first byte */
64        if (-1 == tpChar || 64 == tpChar)
65            return -1;
66        pDest[0] = tpChar << 2;
67        pSrc++;
68        SKIP_CRLF(pSrc);
69        tpChar = get_alphabet_index(*pSrc);
70        if (-1 == tpChar || 64 == tpChar)
71            return -1;
72        pDest[0] |= (tpChar >> 4);
73        pDest[1] = tpChar << 4;                     /* to second byte */
74        pSrc++;
75        SKIP_CRLF(pSrc);
76        tpChar = get_alphabet_index(*pSrc);
77        if (-1 == tpChar)
78            return -1;
79        if (64 == tpChar)           /* end */
80            return pDest - dest + 1;
81        pDest[1] |= (tpChar >> 2);
82        pDest[2] = tpChar << 6;                     /* to third byte */
83        pSrc++;
84        SKIP_CRLF(pSrc);
85        tpChar = get_alphabet_index(*pSrc);
86        if (-1 == tpChar)
87            return -1;
88        if (64 == tpChar)           /* end */
89            return pDest - dest + 2;
90        pDest[2] |= tpChar;
91        pDest += 3;
92        pSrc++;
93    }
94    *srcLen = pSrc - src;
95    return pDest - dest;
96}
97