显示"mqtt.h"和"mqtt.c"文件的代码

以下是一个简单的MQTT客户端的示例代码，包含了mqtt.h和mqtt.c文件的代码：

mqtt.h:

#ifndef MQTT_H
#define MQTT_H

#include <stdint.h>

typedef struct {
    const char *host;
    uint16_t port;
    const char *client_id;
    const char *username;
    const char *password;
} mqtt_config_t;

typedef struct {
    uint8_t *data;
    uint16_t len;
} mqtt_message_t;

typedef struct {
    void (*connected)(void);
    void (*disconnected)(void);
    void (*message_received)(const char *topic, mqtt_message_t *message);
} mqtt_callback_t;

void mqtt_init(mqtt_config_t *config, mqtt_callback_t *callback);
void mqtt_connect(void);
void mqtt_subscribe(const char *topic);
void mqtt_publish(const char *topic, mqtt_message_t *message);
void mqtt_loop(void);

#endif /* MQTT_H */

mqtt.c:

#include "mqtt.h"
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>

#define BUF_SIZE 1024

static int sockfd;
static mqtt_callback_t *callback;
static char buf[BUF_SIZE];

static void mqtt_on_connected(void);
static void mqtt_on_disconnected(void);
static void mqtt_on_message_received(void);

void mqtt_init(mqtt_config_t *config, mqtt_callback_t *cb) {
    callback = cb;
    // TODO: Initialize config and callback
}

void mqtt_connect(void) {
    // TODO: Connect to server
    mqtt_on_connected();
}

void mqtt_subscribe(const char *topic) {
    // TODO: Subscribe to topic
}

void mqtt_publish(const char *topic, mqtt_message_t *message) {
    // TODO: Publish message to topic
}

void mqtt_loop(void) {
    while (1) {
        // TODO: Read from socket and call callback functions
    }
}

static void mqtt_on_connected(void) {
    if (callback->connected != NULL) {
        callback->connected();
    }
}

static void mqtt_on_disconnected(void) {
    if (callback->disconnected != NULL) {
        callback->disconnected();
    }
}

static void mqtt_on_message_received(void) {
    if (callback->message_received != NULL) {
        // TODO: Parse message and call callback function
    }
}