LWIP2.0.2 & FreeRTOS & MQTT 客户端的 使用

1、参考链接 ：http://www.nongnu.org/lwip/2_0_x/group__mqtt.html

2、首先移植好lwip,然后添加 lwip-2.0.2\src\apps\mqtt  文件下 的 mqtt.c 文件，如果有头文件问题，清解决头文件问题！

3、根据参考链接，做一下修改

下面代码中的MQTT 服务器 是我自己搭建的，你也可以找一台Linux 主机搭建一个。。2017年4月24日09:10:19

/*
 * MQTT client for lwIP

 * Author: Erik Andersson

 * Details of the MQTT protocol can be found at:
     http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html 
 *
 */

#include "oneNet_MQTT.h"

#include "string.h"

ip_addr_t mqttServerIpAddr;

//1. Initial steps, reserve memory and make connection to server:

//1.1: Provide storage

//Static allocation: //下面这两句转移到 MAIN.c 中
//  mqtt_client_t static_client;

//  example_do_connect(&static_client);

//Dynamic allocation:
//  mqtt_client_t *client = mqtt_client_new();
//  if(client != NULL) {
//    example_do_connect(&client);
//  }

//1.2: Establish Connection with server

void example_do_connect(mqtt_client_t *client)
{
  struct mqtt_connect_client_info_t ci;
    
  err_t err;
  
  /* Setup an empty client info structure */
  memset(&ci, 0, sizeof(ci));
  
  /* Minimal amount of information required is client identifier, so set it here */ 
  ci.client_id = "lwip_test";
    
    // MQTT服务器地址为：59.110.142.105端口号为：1883
    IP4_ADDR(&mqttServerIpAddr, 59, 110, 142, 105);//配置 MQTT 服务器地址
  
  /* Initiate client and connect to server, if this fails immediately an error code is returned
     otherwise mqtt_connection_cb will be called with connection result after attempting 
     to establish a connection with the server. 
     For now MQTT version 3.1.1 is always used */
  
    //MQTT 服务器进行连接 ,并注册 “连接结果处理”的回调函数，2017年4月12日09:00:12
    
  err = mqtt_client_connect(client, &mqttServerIpAddr, 1883, mqtt_connection_cb, 0, &ci);
  
  /* For now just print the result code if something goes wrong */
  if(err != ERR_OK) 
    {
    printf("mqtt_connect return %d\n", err);
  }
}

//Connection to server can also be probed by calling mqtt_client_is_connected(client) 

//-----------------------------------------------------------------
//2. Implementing the connection status callback
//执行连接状态 的 回调函数
static void mqtt_connection_cb(mqtt_client_t *client, void *arg, mqtt_connection_status_t status)
{
  err_t err;
  if(status == MQTT_CONNECT_ACCEPTED) 
    {
    printf("mqtt_connection_cb: Successfully connected\n");
    
    /* Setup callback for incoming publish requests */
        //注册 消息推送 回调函数 以及消息数据到来的处理函数
    mqtt_set_inpub_callback(client, mqtt_incoming_publish_cb, mqtt_incoming_data_cb, arg);
    
    /* Subscribe to a topic named "subtopic" with QoS level 2, call mqtt_sub_request_cb with result */ 
    err = mqtt_subscribe(client, "subtopic", 2, mqtt_sub_request_cb, arg);

    if(err != ERR_OK)
        {
      printf("mqtt_subscribe return: %d\n", err);
    }
  } 
    else 
    {
    printf("mqtt_connection_cb: Disconnected, reason: %d\n", status);
    
    /* Its more nice to be connected, so try to reconnect */
    example_do_connect(client);
  }  
}

void mqtt_sub_request_cb(void *arg, err_t result)
{
  /* Just print the result code here for simplicity, 
     normal behaviour would be to take some action if subscribe fails like 
     notifying user, retry subscribe or disconnect from server */
  printf("Subscribe result: %d\n", result);
}

//-----------------------------------------------------------------
//3. Implementing callbacks for incoming publish and data

/* The idea is to demultiplex topic and create some reference to be used in data callbacks
   Example here uses a global variable, better would be to use a member in arg
   If RAM and CPU budget allows it, the easiest implementation might be to just take a copy of
   the topic string and use it in mqtt_incoming_data_cb
*/

//这两个函数 一个 处理 消息头 一个 处理 具体的 数据

static int inpub_id;
static void mqtt_incoming_publish_cb(void *arg, const char *topic, u32_t tot_len)
{
    
    //消息来了之后，先进入这里用于判断 是什么主题 的，2017年4月20日09:25:51
    
  printf("Incoming publish at topic \" %s \" with total length %u\r\n", topic, (unsigned int)tot_len);

  /* Decode topic string into a user defined reference */
  if(strcmp(topic, "subtopic") == 0) 
    {
    inpub_id = 0;
  } 
    else if(topic[0] == 'A')        
    {
    /* All topics starting with 'A' might be handled at the same way */
    inpub_id = 1;
  }
    else
    {
    /* For all other topics */
    inpub_id = 2;
  }
}

static void mqtt_incoming_data_cb(void *arg, const u8_t *data, u16_t len, u8_t flags)
{
    //消息来了之后先判断主题 上面那个函数，然后在这里是根据不同的主题，进行不同的处理
    
    uint8_t tempBuff[20]={0};
    
    uint8_t i;
    
    //数据复制到到缓冲区，并加  字符‘0’结尾，因为 发送工具只能发送 字符 不能发送字符串，2017年4月20日09:24:43
    for(i=0;i<len;i++)
    {
        tempBuff[i]=data[i];
    }
    tempBuff[i]=0;
    

  printf("Incoming publish payload with length %d, flags %u\n", len, (unsigned int)flags);

  if(flags & MQTT_DATA_FLAG_LAST) 
    {
    /* Last fragment of payload received (or whole part if payload fits receive buffer
       See MQTT_VAR_HEADER_BUFFER_LEN)  */

    /* Call function or do action depending on reference, in this case inpub_id */
    if(inpub_id == 0) 
        {
      /* Don't trust the publisher, check zero termination */
      if(tempBuff[len] == 0) 
            {
        printf("mqtt_incoming_data_cb: %s\n", (const char *)data);
      }
    }
        else if(inpub_id == 1) 
        {
      /* Call an 'A' function... */
    }
        else 
        {
      printf("mqtt_incoming_data_cb: Ignoring payload...\n");
    }
  }
    else 
    {
    /* Handle fragmented payload, store in buffer, write to file or whatever */
  }
}

//-----------------------------------------------------------------
//4. Using outgoing publish

//使用 向外推送消息
//MQTT传输的消息分为：主题（Topic）和负载（payload）两部分

void example_publish(mqtt_client_t *client, void *arg)
{
  const char *pub_payload= "Hello,MQTT!\r\n";//推送的有效数据(负载)
  err_t err;
    /*
      *    最多一次，这一级别会发生消息丢失或重复，消息发布依赖于底层TCP/IP网络。即：<=1
        *    至多一次，这一级别会确保消息到达，但消息可能会重复。即：>=1
        *    只有一次，确保消息只有一次到达。即：＝1。在一些要求比较严格的计费系统中，可以使用此级别
      */
  u8_t qos = 2; /* 0 1 or 2, see MQTT specification */
    
    //=0 的意思应该是不保留有效负载（有效数据）
  u8_t retain = 0; /* No don't retain such crappy payload... */
    
  err = mqtt_publish(client, "pub_topic", pub_payload, strlen(pub_payload), qos, retain, mqtt_pub_request_cb, arg);
  
    if(err != ERR_OK)
    {
    printf("Publish err: %d.\r\n", err);
  }
    else
    {
      printf("Publish Success.\r\n");
    }
}

/* Called when publish is complete either with sucess or failure */
//推送消息完成后 的 回调函数
void mqtt_pub_request_cb(void *arg, err_t result)
{
  if(result != ERR_OK)
    {
    printf("Publish result: %d\n", result);
  }
}

//-----------------------------------------------------------------
//5. Disconnecting

//Simply call mqtt_disconnect(client)

    static_client.conn_state=0;
    
    /* Initialize MQTT client */
  example_do_connect(&static_client);
    
    while(1)
    {
        
            example_publish(&static_client,(void *)mqtt_pub_request_cb);
            
        /* vTaskDelayUntil是绝对延迟，vTaskDelay是相对延迟。*/
        vTaskDelay(2000);
    }

 上面 的服务器 地址 今天 已经 到期了 ，阿里 的 太贵了 没钱 续费了  哎 2017年6月26日17:15:40