1 /******************************************************************************
3 * Copyright 2017 The Android Open Source Project
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:
9 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 ******************************************************************************/
24 // Scan Response data from Traxxas
25 static constexpr std::array<uint8_t, 18> trx_quirk{
26 {0x14, 0x09, 0x54, 0xFF, 0xFF, 0x20, 0x42, 0x4C, 0x45, 0x05, 0x12, 0xFF,
27 0x00, 0xE8, 0x03, 0x02, 0x0A, 0x00}};
29 class AdvertiseDataParser {
30 // Return true if the packet is malformed, but should be considered valid for
31 // compatibility with already existing devices
32 static bool MalformedPacketQuirk(const std::vector<uint8_t>& ad,
34 auto data_start = ad.begin() + position;
36 // Traxxas - bad name length
37 if ((ad.size() - position) >= 18 &&
38 std::equal(data_start, data_start + 3, trx_quirk.begin()) &&
39 std::equal(data_start + 5, data_start + 11, trx_quirk.begin() + 5) &&
40 std::equal(data_start + 12, data_start + 18, trx_quirk.begin() + 12)) {
48 static void RemoveTrailingZeros(std::vector<uint8_t>& ad) {
51 size_t ad_len = ad.size();
52 while (position != ad_len) {
53 uint8_t len = ad[position];
55 // A field length of 0 would be invalid as it should at least contain the
56 // EIR field type. However, some existing devices send zero padding at the
57 // end of advertisement. If this is the case, cut the zero padding from
58 // end of the packet. Otherwise i.e. gluing scan response to advertise
59 // data will result in data with zero padding in the middle.
61 ad.erase(ad.begin() + position, ad.end());
65 if (position + len >= ad_len) {
74 * Return true if this |ad| represent properly formatted advertising data.
76 static bool IsValid(const std::vector<uint8_t>& ad) {
79 size_t ad_len = ad.size();
80 while (position != ad_len) {
81 uint8_t len = ad[position];
83 // A field length of 0 would be invalid as it should at least contain the
84 // EIR field type. However, some existing devices send zero padding at the
85 // end of advertisement. If this is the case, treat the packet as valid.
87 for (size_t i = position + 1; i < ad_len; i++) {
88 if (ad[i] != 0) return false;
93 // If the length of the current field would exceed the total data length,
94 // then the data is badly formatted.
95 if (position + len >= ad_len) {
96 if (MalformedPacketQuirk(ad, position)) return true;
108 * This function returns a pointer inside the |ad| array of length |ad_len|
109 * where a field of |type| is located, together with its length in |p_length|
111 static const uint8_t* GetFieldByType(const uint8_t* ad, size_t ad_len,
112 uint8_t type, uint8_t* p_length) {
115 while (position != ad_len) {
116 uint8_t len = ad[position];
119 if (position + len >= ad_len) break;
121 uint8_t adv_type = ad[position + 1];
123 if (adv_type == type) {
124 /* length doesn't include itself */
125 *p_length = len - 1; /* minus the length of type */
126 return ad + position + 2;
129 position += len + 1; /* skip the length of data */
137 * This function returns a pointer inside the |adv| where a field of |type| is
138 * located, together with it' length in |p_length|
140 static const uint8_t* GetFieldByType(std::vector<uint8_t> const& ad,
141 uint8_t type, uint8_t* p_length) {
142 return GetFieldByType(ad.data(), ad.size(), type, p_length);