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#include <apdu/apdu.h>
18
19#include <limits>
20
21namespace android {
22
23CommandApdu::CommandApdu(const uint8_t cla, const uint8_t ins, const uint8_t p1, const uint8_t p2,
24        const size_t lc, const size_t le) {
25    constexpr size_t headerSize = 4;
26    constexpr size_t shortLcMax = std::numeric_limits<uint8_t>::max();
27    constexpr size_t shortLeMax = std::numeric_limits<uint8_t>::max() + 1;
28    //constexpr size_t extendedLcMax = std::numeric_limits<uint16_t>::max();
29    constexpr size_t extendedLeMax = std::numeric_limits<uint16_t>::max() + 1;
30
31    const bool extended = lc > shortLcMax || le > shortLeMax;
32    const bool hasLc = lc > 0;
33    const bool hasLe = le > 0;
34    const size_t lcSize = hasLc ? (extended ? 3 : 1) : 0;
35    const size_t leSize = hasLe ? (extended ? (hasLc ? 2 : 3) : 1) : 0;
36    const size_t commandSize = headerSize + lcSize + lc + leSize;
37    mCommand.resize(commandSize, 0);
38
39    // All cases have the header
40    auto it = mCommand.begin();
41    *it++ = cla;
42    *it++ = ins;
43    *it++ = p1;
44    *it++ = p2;
45
46    // Cases 3 & 4 send data
47    if (hasLc) {
48        if (extended) {
49            *it++ = 0;
50            *it++ = 0xff & (lc >> 8);
51        }
52        *it++ = 0xff & lc;
53        mDataBegin = it;
54        it += lc;
55        mDataEnd = it;
56    } else {
57        mDataBegin = mDataEnd = mCommand.end();
58    }
59
60    // Cases 2 & 4 expect data back
61    if (hasLe) {
62        if (extended) {
63            if (!hasLc) {
64                *it++ = 0;
65            }
66            const bool isLeMax = le == extendedLeMax;
67            *it++ = (isLeMax ? 0 : 0xff & (le >> 8));
68            *it++ = (isLeMax ? 0 : 0xff & le);
69        } else {
70            *it++ = (le == shortLeMax ? 0 : 0xff & le);
71        }
72    }
73}
74
75} // namespace android
76