98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/*
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* This program source code file is part of SystemK, a library in the KTag project.
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*
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* 🛡️ <https://ktag.clubk.club> 🃞
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*
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* Copyright © 2016-2025 Joseph P. Kearney and the KTag developers.
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU Affero General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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* details.
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*
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* There should be a copy of the GNU Affero General Public License in the LICENSE
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* file in the root of this repository. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdbool.h>
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#include <string.h>
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#include "SystemK.h"
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#include "BLE_Packets.h"
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#include "BLE_Packet_Tracker.h"
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#define MAX_REMEMBERED_PACKETS 10
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typedef struct
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{
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uint8_t sender_BD_ADDR[BD_ADDR_SIZE];
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BLE_PacketType_T packet_type;
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uint8_t event_number;
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} TrackedPacket_T;
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typedef struct
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{
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TrackedPacket_T packets[MAX_REMEMBERED_PACKETS];
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// Number of unique packets we've seen so far. This value saturates at MAX_REMEMBERED_PACKETS.
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uint8_t count;
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// Index of the oldest packet.
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uint8_t head;
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} PacketTracker_T;
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static PacketTracker_T Tracker =
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{
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.count = 0,
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.head = 0,
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};
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// A packet is _new_ if the combination of BLE adress, type, and event number have not been seen recently.
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bool BLE_IsPacketNew(const uint8_t *sender_BD_ADDR,
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BLE_PacketType_T packet_type,
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uint8_t event_number)
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{
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// Check if the packet already exists in the tracker.
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for (int i = 0; i < Tracker.count; i++)
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{
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int index = (Tracker.head + i) % MAX_REMEMBERED_PACKETS;
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if ((memcmp(Tracker.packets[index].sender_BD_ADDR, sender_BD_ADDR, BD_ADDR_SIZE) == 0) &&
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(Tracker.packets[index].packet_type == packet_type) &&
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(Tracker.packets[index].event_number == event_number))
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{
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// We've already seen this packet.
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return false;
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}
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}
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// The packet is new--find the location to store it.
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int new_index;
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if (Tracker.count < MAX_REMEMBERED_PACKETS)
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{
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// There's space, so just add the new packet at the end.
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new_index = (Tracker.head + Tracker.count) % MAX_REMEMBERED_PACKETS;
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Tracker.count++;
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}
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else
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{
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// No space, so overwrite the oldest packet.
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new_index = Tracker.head;
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Tracker.head = (Tracker.head + 1) % MAX_REMEMBERED_PACKETS;
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}
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// Add the new packet to the tracker.
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memcpy(Tracker.packets[new_index].sender_BD_ADDR, sender_BD_ADDR, BD_ADDR_SIZE);
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Tracker.packets[new_index].packet_type = packet_type;
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Tracker.packets[new_index].event_number = event_number;
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return true;
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}
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// Initialize the MessageTracker
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void BLE_ClearPacketTracker(void)
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{
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Tracker.count = 0;
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Tracker.head = 0;
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}
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