mirror of
https://github.com/kidfromjupiter/nearby.git
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116 lines
4.4 KiB
C++
116 lines
4.4 KiB
C++
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef CORE_INTERNAL_MEDIUMS_BLE_BLE_ADVERTISEMENT_HEADER_H_
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#define CORE_INTERNAL_MEDIUMS_BLE_BLE_ADVERTISEMENT_HEADER_H_
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#include <string>
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#include "internal/platform/byte_array.h"
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namespace nearby {
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namespace connections {
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namespace mediums {
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// Represents the format of the Mediums BLE Advertisement Header used in
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// Advertising + Discovery.
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//
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// [VERSION][NUM_SLOTS][SERVICE_ID_BLOOM_FILTER][ADVERTISEMENT_HASH][L2_CAP_PSM]
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//
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// See go/nearby-ble-design for more information.
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//
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// Note. The object constructed by default constructor or the parameterized
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// constructor with invalid value(s) is treated as invalid instance. Caller
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// should be responsible to call IsValid() to check the instance is invalid in
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// advance before continue on.
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class BleAdvertisementHeader {
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public:
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// Versions of the BleAdvertisementHeader.
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enum class Version {
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kUndefined = 0,
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kV1 = 1,
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kV2 = 2,
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// Version is only allocated 3 bits in the BleAdvertisementHeader, so this
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// can never go beyond V7.
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//
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// V1 is not present because it's an old format used in Nearby Connections
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// before this logic was pushed down into Nearby Mediums. V1 put
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// everything in the service data, while V2 puts the data inside a GATT
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// characteristic so the two are not compatible.
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};
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static constexpr int kAdvertisementHashByteLength = 4;
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static constexpr int kServiceIdBloomFilterByteLength = 10;
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static constexpr int kDefaultPsmValue = 0;
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static constexpr int kPsmValueByteLength = 2;
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// Hashable
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bool operator==(const BleAdvertisementHeader& rhs) const;
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template <typename H>
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friend H AbslHashValue(H h, const BleAdvertisementHeader& b) {
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return H::combine(std::move(h), b.version_,
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b.support_extended_advertisement_, b.num_slots_,
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b.service_id_bloom_filter_, b.advertisement_hash_,
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b.psm_);
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}
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BleAdvertisementHeader() = default;
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BleAdvertisementHeader(Version version, bool support_extended_advertisement,
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int num_slots,
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const ByteArray& service_id_bloom_filter,
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const ByteArray& advertisement_hash, int psm);
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explicit BleAdvertisementHeader(
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const ByteArray& ble_advertisement_header_bytes);
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BleAdvertisementHeader(const BleAdvertisementHeader&) = default;
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BleAdvertisementHeader& operator=(const BleAdvertisementHeader&) = default;
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BleAdvertisementHeader(BleAdvertisementHeader&&) = default;
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BleAdvertisementHeader& operator=(BleAdvertisementHeader&&) = default;
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~BleAdvertisementHeader() = default;
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explicit operator ByteArray() const;
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bool IsValid() const { return version_ == Version::kV2; }
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Version GetVersion() const { return version_; }
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bool IsSupportExtendedAdvertisement() const {
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return support_extended_advertisement_;
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}
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int GetNumSlots() const { return num_slots_; }
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ByteArray GetServiceIdBloomFilter() const { return service_id_bloom_filter_; }
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ByteArray GetAdvertisementHash() const { return advertisement_hash_; }
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int GetPsm() const { return psm_; }
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void SetPsm(int psm) { psm_ = psm; }
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private:
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static constexpr int kVersionAndNumSlotsLength = 1;
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static constexpr int kMinAdvertisementHeaderLength =
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kVersionAndNumSlotsLength + kServiceIdBloomFilterByteLength +
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kAdvertisementHashByteLength;
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static constexpr int kVersionBitmask = 0x0E0;
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static constexpr int kExtendedAdvertismentBitMask = 0x010;
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static constexpr int kNumSlotsBitmask = 0x00F;
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Version version_ = Version::kUndefined;
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bool support_extended_advertisement_ = false;
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int num_slots_ = 0;
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ByteArray service_id_bloom_filter_;
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ByteArray advertisement_hash_;
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int psm_ = kDefaultPsmValue;
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};
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} // namespace mediums
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} // namespace connections
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} // namespace nearby
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#endif // CORE_INTERNAL_MEDIUMS_BLE_BLE_ADVERTISEMENT_HEADER_H_
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