1 /*
2 * Copyright (C) 2021 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 "android-base/hex.h"
18
19 #include "android-base/logging.h"
20
21 namespace android {
22 namespace base {
23
HexString(const void * bytes,size_t len)24 std::string HexString(const void* bytes, size_t len) {
25 CHECK(bytes != nullptr || len == 0) << bytes << " " << len;
26
27 // b/132916539: Doing this the 'C way', std::setfill triggers ubsan implicit conversion
28 const uint8_t* bytes8 = static_cast<const uint8_t*>(bytes);
29 const char chars[] = "0123456789abcdef";
30 std::string result;
31 result.resize(len * 2);
32
33 for (size_t i = 0; i < len; i++) {
34 result[2 * i] = chars[bytes8[i] >> 4];
35 result[2 * i + 1] = chars[bytes8[i] & 0xf];
36 }
37
38 return result;
39 }
40
HexNybbleToValue(char c)41 static uint8_t HexNybbleToValue(char c) {
42 if (c >= '0' && c <= '9') {
43 return c - '0';
44 }
45 if (c >= 'a' && c <= 'f') {
46 return c - 'a' + 10;
47 }
48 if (c >= 'A' && c <= 'Z') {
49 return c - 'A' + 10;
50 }
51 return 0xff;
52 }
53
HexToBytes(const std::string & hex,std::vector<uint8_t> * bytes)54 bool HexToBytes(const std::string& hex, std::vector<uint8_t>* bytes) {
55 if (hex.size() % 2 != 0) {
56 LOG(ERROR) << "HexToBytes: Invalid size: " << hex.size();
57 return false;
58 }
59 bytes->resize(hex.size() / 2);
60 for (unsigned i = 0; i < bytes->size(); i++) {
61 uint8_t hi = HexNybbleToValue(hex[i * 2]);
62 uint8_t lo = HexNybbleToValue(hex[i * 2 + 1]);
63 if (lo > 0xf || hi > 0xf) {
64 LOG(ERROR) << "HexToBytes: Invalid characters: " << hex[i * 2] << ", " << hex[i * 2 + 1];
65 return false;
66 }
67 (*bytes)[i] = (hi << 4) | lo;
68 }
69 return true;
70 }
71
72 } // namespace base
73 } // namespace android
74