| The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 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 */ |
| 20 | static const uint8_t * base64_alphabet = (const uint8_t *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 21 | |
| 22 | #define SKIP_CRLF(p) while('\r' == *(p) || '\n' == *(p)) \ |
| 23 | p++ |
| 24 | |
| 25 | static 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 */ |
| 40 | int32_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 | } |