1 /*
2 * Copyright (C) 2017 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 #ifndef ESED_PN81A_UTILS_H_
18 #define ESED_PN81A_UTILS_H_
19
20 #include <functional>
21 #include <string>
22
23 #include <hidl/Status.h>
24
25 #include <apdu/apdu.h>
26
27 #include "pn81a.h"
28
29 namespace android {
30 namespace esed {
31 namespace pn81a {
32
33 // HIDL
34 using ::android::hardware::Status;
35
36
37 // libapdu
38 using ::android::CommandApdu;
39 using ResponseApdu = ::android::ResponseApdu<const std::vector<uint8_t>>;
40
41 /**
42 * Reads a 32-bit integer from an iterator.
43 * @param first The first position to read from.
44 * @return A tuple of the value read and an iterator to one after the last position read from.
45 */
46 template<typename InputIt>
readBigEndianInt32(InputIt first)47 std::tuple<uint32_t, InputIt> readBigEndianInt32(InputIt first) {
48 uint32_t ret;
49 auto it = first;
50 ret = *it++ << 24;
51 ret |= *it++ << 16;
52 ret |= *it++ << 8;
53 ret |= *it++;
54 return {ret, it};
55 }
56
57 /**
58 * Writes a 32-bit integer to the iterator in big-endian format.
59 * @param value The value to write.
60 * @param first The first position in the iterator.
61 * @return An iterator to one after the last position written to.
62 */
63 template<typename OutputIt>
writeBigEndian(const uint32_t value,OutputIt first)64 OutputIt writeBigEndian(const uint32_t value, OutputIt first) {
65 auto it = first;
66 *it++ = 0xff & (value >> 24);
67 *it++ = 0xff & (value >> 16);
68 *it++ = 0xff & (value >> 8);
69 *it++ = 0xff & value;
70 return it;
71 }
72
73 /**
74 * Transceive a command with the eSE and perform common error checking. When the
75 * handler is called, it has been checked that the transmission to and reception
76 * from the eSE was successful and that the response is in a valid format.
77 */
78 template<typename T, T OK, T FAILED>
79 T transceive(::android::esed::EseInterface& ese, const CommandApdu& command,
80 std::function<T(const ResponseApdu&)> handler = {}) {
81 // +1 for max size of extended response, +2 for status bytes
82 constexpr size_t MAX_RESPONSE_SIZE = std::numeric_limits<uint16_t>::max() + 1 + 2;
83 std::vector<uint8_t> responseBuffer(MAX_RESPONSE_SIZE);
84 const int ret = ese.transceive(command.vector(), responseBuffer);
85
86 // Check eSE communication was successful
87 if (ret < 0) {
88 std::string errMsg = "Failed to transceive data between AP and eSE";
89 if (ese.error()) {
90 errMsg += " (" + std::to_string(ese.error_code()) + "): " + ese.error_message();
91 } else {
92 errMsg += ": reason unknown";
93 }
94 LOG(ERROR) << errMsg;
95 return FAILED;
96 }
97 const size_t recvd = static_cast<size_t>(ret);
98
99 // Need to recalculate the maximum response size if this fails
100 if (recvd > MAX_RESPONSE_SIZE) {
101 LOG(ERROR) << "eSE response was longer than the buffer, check the buffer size.";
102 return FAILED;
103 }
104 responseBuffer.resize(recvd);
105
106 // Check for ISO 7816-4 APDU response format errors
107 ResponseApdu apdu{responseBuffer};
108 if (!apdu.ok()) {
109 LOG(ERROR) << "eSE response was invalid.";
110 return FAILED;
111 }
112
113 // Call handler if one was provided
114 if (handler) {
115 return handler(apdu);
116 }
117
118 return OK;
119 }
120
121 /**
122 * Checks that the amount of data in the response APDU matches the expected
123 * value.
124 */
125 template<typename T, T OK, T FAILED>
checkLength(const ResponseApdu & apdu,const size_t size)126 T checkLength(const ResponseApdu& apdu, const size_t size) {
127 if (apdu.dataSize() != size) {
128 LOG(ERROR) << "eSE response was the wrong length.";
129 return FAILED;
130 }
131 return OK;
132 }
133
134 /**
135 * Checks that the response APDU does no encode an error and that the amount of
136 * data matches the expected value.
137 */
138 template<typename T, T OK, T FAILED>
checkNoErrorAndLength(const ResponseApdu & apdu,const size_t size)139 T checkNoErrorAndLength(const ResponseApdu& apdu, const size_t size) {
140 if (apdu.isError()) {
141 LOG(ERROR) << "eSE operation failed";
142 return FAILED;
143 }
144 return checkLength<T, OK, FAILED>(apdu, size);
145 }
146
147 } // namespace android
148 } // namespace esed
149 } // namespace pn81a
150
151 #endif // ESED_PN81A_UTILS_H_
152