1 /******************************************************************************
2 *
3 * Copyright (C) 2012 Broadcom Corporation
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 ******************************************************************************/
18 #include "CrcChecksum.h"
19
20 #include <android-base/stringprintf.h>
21 #include <base/logging.h>
22 #include <fcntl.h>
23 #include <unistd.h>
24
25 #include <string>
26
27 using android::base::StringPrintf;
28
29 extern bool nfc_debug_enabled;
30
31 static const uint16_t crctab[256] = {
32 0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241, 0xc601,
33 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440, 0xcc01, 0x0cc0,
34 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40, 0x0a00, 0xcac1, 0xcb81,
35 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841, 0xd801, 0x18c0, 0x1980, 0xd941,
36 0x1b00, 0xdbc1, 0xda81, 0x1a40, 0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01,
37 0x1dc0, 0x1c80, 0xdc41, 0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0,
38 0x1680, 0xd641, 0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081,
39 0x1040, 0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
40 0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441, 0x3c00,
41 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41, 0xfa01, 0x3ac0,
42 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840, 0x2800, 0xe8c1, 0xe981,
43 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41, 0xee01, 0x2ec0, 0x2f80, 0xef41,
44 0x2d00, 0xedc1, 0xec81, 0x2c40, 0xe401, 0x24c0, 0x2580, 0xe541, 0x2700,
45 0xe7c1, 0xe681, 0x2640, 0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0,
46 0x2080, 0xe041, 0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281,
47 0x6240, 0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
48 0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41, 0xaa01,
49 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840, 0x7800, 0xb8c1,
50 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41, 0xbe01, 0x7ec0, 0x7f80,
51 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40, 0xb401, 0x74c0, 0x7580, 0xb541,
52 0x7700, 0xb7c1, 0xb681, 0x7640, 0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101,
53 0x71c0, 0x7080, 0xb041, 0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0,
54 0x5280, 0x9241, 0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481,
55 0x5440, 0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
56 0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841, 0x8801,
57 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40, 0x4e00, 0x8ec1,
58 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41, 0x4400, 0x84c1, 0x8581,
59 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641, 0x8201, 0x42c0, 0x4380, 0x8341,
60 0x4100, 0x81c1, 0x8081, 0x4040,
61 };
62
63 /*******************************************************************************
64 **
65 ** Function crcChecksumCompute
66 **
67 ** Description Compute a checksum on a buffer of data.
68 **
69 ** Returns 2-byte checksum.
70 **
71 *******************************************************************************/
crcChecksumCompute(const unsigned char * buffer,int bufferLen)72 uint16_t crcChecksumCompute(const unsigned char* buffer, int bufferLen) {
73 uint16_t crc = 0;
74 const unsigned char* cp = buffer;
75 int cnt = bufferLen;
76
77 while (cnt--) {
78 crc = ((crc >> 8) & 0xff) ^ crctab[(crc & 0xff) ^ *cp++];
79 }
80 return (crc);
81 }
82
83 /*******************************************************************************
84 **
85 ** Function crcChecksumVerifyIntegrity
86 **
87 ** Description Detect any corruption in a file by computing a checksum.
88 ** filename: file name.
89 **
90 ** Returns True if file is good.
91 **
92 *******************************************************************************/
crcChecksumVerifyIntegrity(const char * filename)93 bool crcChecksumVerifyIntegrity(const char* filename) {
94 DLOG_IF(INFO, nfc_debug_enabled)
95 << StringPrintf("%s: filename=%s", __func__, filename);
96 bool isGood = false;
97 int fileStream = open(filename, O_RDONLY);
98 if (fileStream >= 0) {
99 uint16_t checksum = 0;
100 std::string data;
101 size_t actualReadCrc = read(fileStream, &checksum, sizeof(checksum));
102 while (true) {
103 char buffer[1024];
104 ssize_t actualReadData = read(fileStream, buffer, sizeof(buffer));
105 if (actualReadData > 0)
106 data.append(buffer, actualReadData);
107 else
108 break;
109 }
110 close(fileStream);
111 if ((actualReadCrc == sizeof(checksum)) && (data.size() > 0)) {
112 DLOG_IF(INFO, nfc_debug_enabled)
113 << StringPrintf("%s: data size=%zu", __func__, data.size());
114 if (checksum ==
115 crcChecksumCompute((const unsigned char*)data.data(), data.size()))
116 isGood = true;
117 else
118 LOG(ERROR) << StringPrintf("%s: checksum mismatch", __func__);
119 } else
120 LOG(ERROR) << StringPrintf("%s: invalid length", __func__);
121 } else
122 isGood = true; // assume file does not exist
123 return isGood;
124 }
125