2020-06-08 11:15:05 +02:00
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/*
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* Copyright (c) 2020 Olaf Landsiedel
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/types.h>
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#include <stddef.h>
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#include <sys/printk.h>
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#include <sys/util.h>
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#include <string.h>
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#include <bluetooth/bluetooth.h>
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#include <bluetooth/hci.h>
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#include "exposure-notification.h"
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#include "covid_types.h"
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#include "contacts.h"
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#include "covid.h"
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typedef struct covid_adv_svd {
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uint16_t ens;
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rolling_proximity_identifier_t rolling_proximity_identifier;
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associated_encrypted_metadata_t associated_encrypted_metadata;
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} __packed covid_adv_svd_t;
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const static bt_metadata_t bt_metadata= {
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.version = 0b00100000,
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.tx_power = 0, //TODO set to actual transmit power
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.rsv1 = 0,
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.rsv2 = 0,
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};
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#define COVID_ENS (0xFD6F)
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static covid_adv_svd_t covid_adv_svd= {
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.ens = COVID_ENS,
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//do not initialiuze the rest of the packet, will write this later
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};
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static struct bt_data ad[] = {
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BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
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BT_DATA_BYTES(BT_DATA_UUID16_ALL, 0x6f, 0xfd), //0xFD6F Exposure Notification Service
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BT_DATA(BT_DATA_SVC_DATA16, &covid_adv_svd, sizeof(covid_adv_svd_t))
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};
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2020-06-12 12:25:31 +02:00
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static void scan_cb(const bt_addr_le_t *addr, int8_t rssi, uint8_t adv_type, struct net_buf_simple *buf)
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2020-06-08 11:15:05 +02:00
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{
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if( adv_type == 3 ){
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2020-06-12 12:25:31 +02:00
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uint8_t len = 0;
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2020-06-08 11:15:05 +02:00
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while (buf->len > 1) {
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2020-06-12 12:25:31 +02:00
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uint8_t type;
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2020-06-08 11:15:05 +02:00
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len = net_buf_simple_pull_u8(buf);
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if (!len) {
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break;
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}
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/* Check if field length is correct */
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if (len > buf->len || buf->len < 1) {
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break;
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}
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type = net_buf_simple_pull_u8(buf);
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if (type == BT_DATA_SVC_DATA16 && len == sizeof(covid_adv_svd_t) + 1){
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covid_adv_svd_t* rx_adv = (covid_adv_svd_t*) buf->data;
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if (rx_adv->ens == COVID_ENS){
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check_add_contact(k_uptime_get() / 1000, &rx_adv->rolling_proximity_identifier, &rx_adv->associated_encrypted_metadata, rssi);
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}
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}
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net_buf_simple_pull(buf, len - 1); //consume the rest, note we already consumed one byte via net_buf_simple_pull_u8(buf)
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}
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}
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}
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#define NUM_PERIOD_KEYS (14)
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static period_t periods[NUM_PERIOD_KEYS];
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static int current_period_index = 0;
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static ENIntervalNumber currentInterval;
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static unsigned int period_cnt = 0;
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static ENPeriodMetadataEncryptionKey periodMetadataEncryptionKey;
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static ENIntervalIdentifier intervalIdentifier;
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static associated_encrypted_metadata_t encryptedMetadata;
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static bool init = 1;
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static bool infected = 0;
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2020-09-13 20:42:20 +02:00
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static void test_against_fixtures(void) {
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// First define base values
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ENIntervalNumber intervalNumber = 2642976;
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ENPeriodKey periodKey = {.b = {0x75, 0xc7, 0x34, 0xc6, 0xdd, 0x1a, 0x78, 0x2d, 0xe7, 0xa9, 0x65, 0xda, 0x5e, 0xb9, 0x31, 0x25}};
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unsigned char metadata[4] = {0x40, 0x08, 0x00, 0x00};
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// define the expected values
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ENPeriodIdentifierKey expectedPIK = {.b = {0x18, 0x5a, 0xd9, 0x1d, 0xb6, 0x9e, 0xc7, 0xdd, 0x04, 0x89, 0x60, 0xf1, 0xf3, 0xba, 0x61, 0x75}};
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ENPeriodMetadataEncryptionKey expectedPMEK = {.b = {0xd5, 0x7c, 0x46, 0xaf, 0x7a, 0x1d, 0x83, 0x96, 0x5b, 0x9b, 0xed, 0x8b, 0xd1, 0x52, 0x93, 0x6a}};
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ENIntervalIdentifier expectedIntervalIdentifier = {.b = {0x8b, 0xe6, 0xcd, 0x37, 0x1c, 0x5c, 0x89, 0x16, 0x04, 0xbf, 0xbe, 0x49, 0xdf, 0x84, 0x50, 0x96}};
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unsigned char expectedEncryptedMetadata[4] = {0x72, 0x03, 0x38, 0x74};
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ENPeriodIdentifierKey pik;
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en_derive_period_identifier_key(&pik, &periodKey);
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printk("expectedPIK: "); print_key(&expectedPIK); printk(", ");
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printk("actualPIK: "); print_key(&pik); printk(", ");
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ENIntervalIdentifier intervalIdentifier;
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en_derive_interval_identifier(&intervalIdentifier, &pik, intervalNumber);
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printk("expectedRPI: "); print_key(&expectedIntervalIdentifier); printk(", ");
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printk("actualRPI: "); print_key(&intervalIdentifier); printk(", ");
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/*ENPeriodMetadataEncryptionKey pmek;
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en_derive_period_metadata_encryption_key(&pmek, &periodKey);
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TEST_ASSERT_EQUAL_KEY(expectedPMEK, pmek);
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unsigned char encryptedMetadata[sizeof(metadata)] = {0};
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en_encrypt_interval_metadata(&pmek, &intervalIdentifier, metadata, encryptedMetadata, sizeof(metadata));
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TEST_ASSERT_EQUAL_CHAR_ARRAY(expectedEncryptedMetadata, encryptedMetadata, sizeof(expectedEncryptedMetadata));*/
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}
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2020-06-08 11:15:05 +02:00
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static void new_period_key(time_t currentTime ){
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printk("\n----------------------------------------\n\n");
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printk("\n----------------------------------------\n\n");
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printk("*** New Period\n");
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current_period_index = period_cnt % NUM_PERIOD_KEYS;
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periods[current_period_index].periodInterval = en_get_interval_number_at_period_start(currentTime);
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printk("periodInterval %u\n", periods[current_period_index].periodInterval);
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en_generate_period_key(&periods[current_period_index].periodKey);
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period_cnt++;
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}
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//To be called when new keys are needed
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static void check_keys(struct k_work *work){
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// we check the current time to know if we actually need to regenerate anything
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// TODO: Use real unix timestamp!: currentTime = time(NULL);
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time_t currentTime = k_uptime_get() / 1000;
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ENIntervalNumber newInterval = en_get_interval_number(currentTime);
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if( currentInterval != newInterval || init){
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currentInterval = newInterval;
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bool newPeriod = ((currentInterval - periods[current_period_index].periodInterval) >= EN_TEK_ROLLING_PERIOD);
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// we check if we need to generate new keys
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if (newPeriod || init) {
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new_period_key(currentTime);
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}
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// we now generate the new interval identifier and re-encrypt the metadata
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en_derive_interval_identifier(&intervalIdentifier, &periods[current_period_index].periodKey, currentInterval);
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en_encrypt_interval_metadata(&periodMetadataEncryptionKey, &intervalIdentifier, (unsigned char*)&bt_metadata, (unsigned char*)&encryptedMetadata, sizeof(associated_encrypted_metadata_t));
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// broadcast intervalIdentifier plus encryptedMetada according to specs
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//printk("\n----------------------------------------\n\n");
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printk("Time: %llu, ", currentTime);
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printk("Interval: %u, ", currentInterval);
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2020-09-13 20:42:20 +02:00
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printk("TEK: "); print_rpi((rolling_proximity_identifier_t*)&periods[current_period_index].periodKey); printk(", ");
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2020-06-08 11:15:05 +02:00
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printk("RPI: "); print_rpi((rolling_proximity_identifier_t*)&intervalIdentifier); printk(", ");
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printk("AEM: "); print_aem(&encryptedMetadata); printk("\n");
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//TODO do we have to worry about race conditions here?
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//worst case: we would be advertising a wrong key for a while
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memcpy(&covid_adv_svd.rolling_proximity_identifier, &intervalIdentifier, sizeof(rolling_proximity_identifier_t));
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memcpy(&covid_adv_svd.associated_encrypted_metadata, &encryptedMetadata, sizeof(associated_encrypted_metadata_t));
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if( !init ){
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key_change(current_period_index);
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}
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init = 0;
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}
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}
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K_WORK_DEFINE(my_work, check_keys);
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static void my_timer_handler(struct k_timer *dummy){
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k_work_submit(&my_work);
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}
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K_TIMER_DEFINE(my_timer, my_timer_handler, NULL);
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static const struct bt_le_scan_param scan_param = {
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.type = BT_HCI_LE_SCAN_PASSIVE,
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.filter_dup = BT_HCI_LE_SCAN_FILTER_DUP_DISABLE,
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.interval = 0x0010, //Scan Interval (N * 0.625 ms), TODO: set to correct interval
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.window = 0x0010, //Scan Window (N * 0.625 ms), TODO: set to correct interval
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};
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#define KEY_CHECK_INTERVAL (K_MSEC(EN_INTERVAL_LENGTH * 1000 / 10))
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int init_covid(){
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2020-09-13 20:42:20 +02:00
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2020-06-08 11:15:05 +02:00
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// TODO: Use real unix timestamp!: currentTime = time(NULL);
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init = 1;
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period_cnt = 0;
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infected = 0;
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2020-09-13 20:42:20 +02:00
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test_against_fixtures();
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2020-06-08 11:15:05 +02:00
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check_keys(NULL);
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int err = 0;
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err = bt_le_scan_start(&scan_param, scan_cb);
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if (err) {
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printk("Starting scanning failed (err %d)\n", err);
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return err;
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}
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2020-09-13 20:42:20 +02:00
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2020-06-08 11:15:05 +02:00
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k_timer_start(&my_timer, KEY_CHECK_INTERVAL, KEY_CHECK_INTERVAL);
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return 0;
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}
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int do_covid(){
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//printk("covid start\n");
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int err = 0;
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err = bt_le_adv_start(BT_LE_ADV_NCONN, ad, ARRAY_SIZE(ad), NULL, 0);
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if (err) {
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printk("Advertising failed to start (err %d)\n", err);
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return err;
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}
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k_sleep(K_SECONDS(10));
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err = bt_le_adv_stop();
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if (err) {
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printk("Advertising failed to stop (err %d)\n", err);
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return err;
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}
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//printk("covid end\n");
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return 0;
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}
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bool get_infection(){
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return infected;
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}
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void set_infection(bool _infected){
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infected = _infected;
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}
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unsigned int get_period_cnt_if_infected(){
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if( !infected ){
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return 0;
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}
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return period_cnt;
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}
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period_t* get_period_if_infected(unsigned int id, size_t* size){
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if( !infected || id >= NUM_PERIOD_KEYS || id >= period_cnt ){
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*size = 0;
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return NULL;
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}
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*size = sizeof(period_t);
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return &periods[id];
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}
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int get_index_by_interval(ENIntervalNumber periodInterval){
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int index = 0;
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while( index < NUM_PERIOD_KEYS || index < period_cnt ){
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if( periods[index].periodInterval == periodInterval){
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return index;
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}
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index++;
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}
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return -1;
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}
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