Receive min/max temperature on iot device

iot/Makefile

@@ -1,7 +1,9 @@
-FILES=main.c brokers/mqtt.c brokers/amqp.c devices/temperature.c devices/display.c devices/buzzer.c device_id.c
+FILES=main.c brokers/mqtt.c brokers/amqp.c devices/temperature.c devices/display.c devices/buzzer.c device_properties.c
 
 # libgpiod version must be < 2.0
 
-all: $(FILES)
-	$(CC) -lmosquitto -lrabbitmq -pthread -li2c -lgpiod $(FILES)
+# apt install libmosquitto-dev librabbitmq-dev libi2c-dev libgpiod-dev libcjson-dev
+
+all: $(FILES)
+	$(CC) -lmosquitto -lrabbitmq -pthread -li2c -lgpiod -lcjson $(FILES)
 

iot/brokers/amqp.c

@@ -1,13 +1,20 @@
 #include <rabbitmq-c/amqp.h>
 #include <rabbitmq-c/tcp_socket.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
 
 #include "../config.h"
 
 amqp_connection_state_t conn;
 amqp_socket_t *socket;
+amqp_channel_t channel = 1;
 
 void broker_on_connect(void);
 
+bool broker_on_message(char *exchange, char *message);
+
 void amqp_send_message(char *queue, char *message)
 {
 	amqp_basic_properties_t props;
@@ -15,7 +22,22 @@ void amqp_send_message(char *queue, char *message)
 	props.content_type = amqp_literal_bytes("text/plain");
 	props.delivery_mode = 2;
 
-	amqp_basic_publish(conn, 1, amqp_cstring_bytes(queue), amqp_cstring_bytes(queue), 0, 0, &props, amqp_cstring_bytes(message));
+	amqp_basic_publish(conn, channel, amqp_cstring_bytes(queue), amqp_cstring_bytes(queue), 0, 0, &props, amqp_cstring_bytes(message));
+}
+
+void amqp_subscribe(char *queue)
+{
+	amqp_basic_consume(conn, channel, amqp_cstring_bytes(queue), amqp_cstring_bytes("iot"), 1, 0, 0, amqp_empty_table);
+}
+
+char *amqp_bytes_to_cstring(amqp_bytes_t bytes)
+{
+	char *str = malloc(bytes.len + 1);
+
+	memcpy(str, bytes.bytes, bytes.len);
+	str[bytes.len] = '\0';
+
+	return str;
 }
 
 void init_amqp(void)
@@ -27,9 +49,24 @@ void init_amqp(void)
 
 	amqp_login(conn, "/", 0, 131072, 0, AMQP_SASL_METHOD_PLAIN, AMQP_USER, AMQP_PASSWORD);
 
-	amqp_channel_open(conn, 1);
+	amqp_channel_open(conn, channel);
 
 	broker_on_connect();
 
-	for (;;);
+	while (true) {
+		amqp_envelope_t envelope;
+		amqp_consume_message(conn, &envelope, NULL, 0);
+
+		char *exchange_name = amqp_bytes_to_cstring(envelope.exchange);
+		char *message = amqp_bytes_to_cstring(envelope.message.body);
+
+		if (broker_on_message(exchange_name, message)) {
+			amqp_basic_ack(conn, channel, envelope.delivery_tag, 0);
+		}
+
+		free(exchange_name);
+		free(message);
+		amqp_destroy_envelope(&envelope);
+	}
 }
+

iot/brokers/amqp.h

@@ -2,3 +2,5 @@ void init_amqp(void);
 
 void amqp_send_message(char *topic, char *message);
 
+void amqp_subscribe(char *queue);
+

iot/device_id.c

@@ -1,46 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-
-#include "device_id.h"
-
-#define DEVICE_ID_SIZE 5
-
-char *get_device_id(void)
-{
-	FILE *file = fopen("device_id.txt", "r");
-
-	if (!file) {
-		char *device_id = generate_device_id();
-
-		file = fopen("device_id.txt", "w");
-		fprintf(file, "%s", device_id);
-		fclose(file);
-
-		return device_id;
-	}
-
-	char *device_id = malloc(DEVICE_ID_SIZE + 1);
-	fgets(device_id, DEVICE_ID_SIZE + 1, file);
-	fclose(file);
-
-	return device_id;
-}
-
-char *generate_device_id(void)
-{
-	char *device_id = malloc(DEVICE_ID_SIZE + 1);
-
-	for (int i = 0; i < DEVICE_ID_SIZE; i++) {
-		device_id[i] = 'A' + (random() % 26);
-	}
-
-	device_id[DEVICE_ID_SIZE] = '\0';
-
-	return device_id;
-}
-
-void destroy_device_id(char *device_id)
-{
-	free(device_id);
-}
-

iot/device_id.h

@@ -1,6 +0,0 @@
-char *get_device_id(void);
-
-char *generate_device_id(void);
-
-void destroy_device_id(char *device_id);
-

iot/device_properties.c

@@ -0,0 +1,80 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+
+#include "device_properties.h"
+
+#define DEVICE_ID_SIZE 5
+
+char *get_device_id(void)
+{
+	FILE *file = fopen("device_id.txt", "r");
+
+	if (!file) {
+		char *device_id = generate_device_id();
+
+		file = fopen("device_id.txt", "w");
+		fprintf(file, "%s", device_id);
+		fclose(file);
+
+		return device_id;
+	}
+
+	char *device_id = malloc(DEVICE_ID_SIZE + 1);
+	fgets(device_id, DEVICE_ID_SIZE + 1, file);
+	fclose(file);
+
+	return device_id;
+}
+
+char *generate_device_id(void)
+{
+	char *device_id = malloc(DEVICE_ID_SIZE + 1);
+
+	for (int i = 0; i < DEVICE_ID_SIZE; i++) {
+		device_id[i] = 'A' + (random() % 26);
+	}
+
+	device_id[DEVICE_ID_SIZE] = '\0';
+
+	return device_id;
+}
+
+void set_min_temperature(double temperature)
+{
+	FILE *file = fopen("min_temp.txt", "w");
+	fprintf(file, "%lf", temperature);
+	fclose(file);
+}
+
+double get_min_temperature(void)
+{
+	FILE *file = fopen("min_temp.txt", "r");
+	if (!file) return NAN;
+
+	double temperature = NAN;
+	fscanf(file, "%lf", &temperature);
+	fclose(file);
+
+	return temperature;
+}
+
+void set_max_temperature(double temperature)
+{
+	FILE *file = fopen("max_temp.txt", "w");
+	fprintf(file, "%lf", temperature);
+	fclose(file);
+}
+
+double get_max_temperature(void)
+{
+	FILE *file = fopen("max_temp.txt", "r");
+	if (!file) return NAN;
+
+	double temperature = NAN;
+	fscanf(file, "%lf", &temperature);
+	fclose(file);
+
+	return temperature;
+}
+

iot/device_properties.h

@@ -0,0 +1,9 @@
+char *get_device_id(void);
+char *generate_device_id(void);
+
+void set_min_temperature(double temperature);
+double get_min_temperature(void);
+
+void set_max_temperature(double temperature);
+double get_max_temperature(void);
+

iot/main.c

@@ -5,12 +5,14 @@
 #include <string.h>
 #include <stdio.h>
 #include <time.h>
+#include <math.h>
+#include <cjson/cJSON.h>
 
 #include "brokers/amqp.h"
 #include "devices/temperature.h"
 #include "devices/display.h"
 #include "devices/buzzer.h"
-#include "device_id.h"
+#include "device_properties.h"
 
 void *sound_alarm(void *arg)
 {
@@ -31,9 +33,6 @@ void *sound_alarm(void *arg)
 
 void *watch_temperature(void *arg)
 {
-	// TODO change
-	int max_temperature = 27, min_temperature = 18;
-
 	char *device_id = get_device_id();
 
 	printf("Device ID: %s\n", device_id);
@@ -49,6 +48,8 @@ void *watch_temperature(void *arg)
 
 	while (true) {
 		// Retrieve data
+		double min_temperature = get_min_temperature();
+		double max_temperature = get_max_temperature();
 		double temperature = get_temperature(temp_handle);
 		size_t timestamp = time(NULL);
 
@@ -76,7 +77,10 @@ void *watch_temperature(void *arg)
 		free(str);
 
 		// Sound alarm if applicable
-		if (temperature < min_temperature || temperature > max_temperature) {
+		if (
+			min_temperature != NAN && max_temperature != NAN &&
+			(temperature < min_temperature || temperature > max_temperature)
+		) {
 			pthread_t alarm_thread;
 			pthread_create(&alarm_thread, NULL, sound_alarm, NULL);
 		}
@@ -86,17 +90,53 @@ void *watch_temperature(void *arg)
 		sleep(60);
 	}
 
-	destroy_device_id(device_id);
+	free(device_id);
 
 	return NULL;
 }
 
 void broker_on_connect(void)
 {
+	amqp_subscribe("temperature-limits");
+
 	pthread_t temperature_thread;
 	pthread_create(&temperature_thread, NULL, watch_temperature, NULL);
 }
 
+bool broker_on_message(char *exchange, char *message)
+{
+	cJSON *json = cJSON_Parse(message);
+	if (cJSON_IsInvalid(json)) goto cancel;
+
+	// Get values
+	cJSON *reference_id = cJSON_GetObjectItem(json, "ReferenceId");
+	if (!cJSON_IsString(reference_id)) goto cancel;
+
+	cJSON *min_temp = cJSON_GetObjectItem(json, "TempLow");
+	if (!cJSON_IsNumber(min_temp)) goto cancel;
+
+	cJSON *max_temp = cJSON_GetObjectItem(json, "TempHigh");
+	if (!cJSON_IsNumber(min_temp)) goto cancel;
+
+	if (strcmp(reference_id->valuestring, get_device_id()) != 0) {
+		goto cancel;
+	}
+
+	printf("Min temperature: %lf, Max temperature: %lf\n", min_temp->valuedouble, max_temp->valuedouble);
+
+	set_min_temperature(min_temp->valuedouble);
+	set_max_temperature(max_temp->valuedouble);
+
+	cJSON_Delete(json);
+
+	return true;
+
+cancel:
+	cJSON_Delete(json);
+
+	return false;
+}
+
 int main(void)
 {
 	srand(time(NULL));