前言

在上几篇文章中我们用MQTT.fx模拟客户端实现了与阿里云物联网平台的双向通信，接下来我们自己动手编程使用mosquitto库实现一个发布端。

iniparser配置文件

iniparser介绍
与阿里云进行通信时，我们需要如下一些信息，例如在使用MQTT.fx时：

阿里云配置和MQTT.fx使用
在上篇文章中阿里云配置文件另外之前发布和订阅的topic也要记下来：

这些都是我们在项目中要用到的配置信息，具体应用在：

#客户端id
clientid：
struct mosquitto *mosquitto_new( const char * id, bool clean_session, void * obj )
#连接阿里云的端口,主机名
brokeraddress and brokerport：
int mosquitto_connect( struct mosquitto * mosq, const char * host, int port, int keepalive )
#连接阿里云账号和密码
username and password：
int mosquitto_username_pw_set(struct mosquitto * mosq, const char *username, const char *password )
#订阅的主题
topic：
int mosquitto_publish( struct mosquitto * mosq, int * mid, const char * topic, int payloadlen, const void * payload, int qos, bool retain )

当然可以直接写死在代码里，但是这样一来，代码复用性不高，换一个设备那么就要改一次源码来更改设备配置信息。MQTT主机使用可以看这篇博客.

所以我们写一个.ini文件，这样当我们更换设备的时候只需要修改这个.ini文件中的信息即可。然后在代码中使用iniparser库中API。

cJSON

JSON(JavaScript Object Notation, JS 对象简谱) 是一种轻量级的数据交换格式。它基于 ECMAScript (欧洲计算机协会制定的js规范)的一个子集，采用完全独立于编程语言的文本格式来存储和表示数据。简洁和清晰的层次结构使得 JSON 成为理想的数据交换语言。 易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。

阿里云上payload must be json format 负载（消息）必须为cJSON格式。
因为使用的阿里云提供的标准物模型，所以消息格式应该遵循阿里云的规范。这就是我们要使用cJSON的原因。

要是已其他格式发送,阿里云收到了消息，但是因为参数不匹配，无法对消息进行解析，也就无法获取到温度消息
学习cJSON可以参考博客

sqlite3数据库

SQLite是一个进程内的库，实现了自给自足的、无服务器的、零配置的、事务性的 SQL 数据库引擎。它是一个零配置的数据库，这意味着与其他数据库不一样，您不需要在系统中配置。
就像其他数据库，SQLite 引擎不是一个独立的进程，可以按应用程序需求进行静态或动态连接。SQLite 直接访问其存储文件。

sqlite3数据库优点

1.不需要一个单独的服务器进程或操作的系统（无服务器的）。
2.SQLite 不需要配置，这意味着不需要安装或管理。
3. 一个完整的 SQLite数据库是存储在一个单一的跨平台的磁盘文件。
4. SQLite 是非常小的，是轻量级的，完全配置时小于 400KiB，省略可选功能配置时小于250KiB。
5.SQLite 是自给自足的，这意味着不需要任何外部的依赖。
6 SQLite 事务是完全兼容ACID 的，允许从多个进程或线程安全访问。
7.SQLite 支持 SQL92（SQL2）标准的大多数查询语言的功能。
8. SQLite 使用ANSI-C 编写的，并提供了简单和易于使用的 API。
9. SQLite 可在 UNIX（Linux, Mac OS-X, Android,iOS）和 Windows（Win32, WinCE, WinRT）中运行。

sqlite3库函数

流程图

配置信息

#include "iniparser.h"
#include "mqtt_conf.h"
#include <stdio.h>
#include <string.h>/* 载入设置参数 */
int get_config(char *path,mqtt_user_data *mqtt,int mode)
{dictionary      *ini = NULL;const char      *brokeraddress;int             brokerport;const char      *username;const char      *password;const char      *clientid;const char      *topic;int             Qos;const char      *method;const char      *time;const char      *jsonid;const char      *identifier;const char      *version;if(!path || !mqtt){printf("invalid_argument: %s\n",__FUNCTION__);return -1;}ini = iniparser_load(path);if(!ini){printf("iniparser_load failed!\n");return -1;}brokeraddress = iniparser_getstring(ini,"address:host",DEFAULT_BROKER_ADDRESS);brokerport= iniparser_getint(ini,"address:port",DEFAULT_BROKER_PORT);username = iniparser_getstring(ini,"user_name_pwd:username",DEFAULT_USERNAME);password = iniparser_getstring(ini,"user_name_pwd:pwd",DEFAULT_PASSWORD);clientid = iniparser_getstring(ini,"clientid:id",DEFAULT_CLIENTID);identifier = iniparser_getstring(ini,"ali_json:identifier",DEFAULT_JSONID);if(mode == SUB){topic = iniparser_getstring(ini,"sub_topic:topic",DEFAULT_SUB_TOPIC);}else if(mode == PUB){topic = iniparser_getstring(ini,"pub_topic:topic",DEFAULT_PUB_TOPIC);method = iniparser_getstring(ini,"ali_json:method",DEFAULT_METHOD);//time = iniparser_getstring(ini,"ali_time:time",DEFAULT_TIME);//jsonid = iniparser_getstring(ini,"ali_json:id",DEFAULT_JSONID);version = iniparser_getstring(ini,"ali_json:version",DEFAULT_VERSION);}else if(mode != SUB && mode != PUB){printf("invalid_argument : %s mode!\n",__FUNCTION__);return -1;}strncpy(mqtt->brokeraddress,brokeraddress,SIZE);mqtt->brokerport = brokerport;mqtt->Qos        = Qos;strncpy(mqtt->username,username,SIZE);strncpy(mqtt->password,password,SIZE);strncpy(mqtt->clientid,clientid,SIZE);strncpy(mqtt->topic,topic,SIZE);          strncpy(mqtt->identifier,identifier,SIZE);if(mode == PUB){strncpy(mqtt->method,method,SIZE);//strncpy(mqtt->time,time,SIZE);//strncpy(mqtt->jsonid,jsonid,SIZE);strncpy(mqtt->version,version,SIZE);}iniparser_freedict(ini);return 0;}

#ifndef MQTT_CONF_H
#define MQTT_CONF_H#define  SIZE                1024
#define KEEP_ALIVE          60enum{SUB ,PUB
};typedef struct mqtt_user_data
{char    brokeraddress[SIZE] ;int     brokerport;char    username[SIZE];char    password[SIZE];char    clientid[SIZE];char    topic[SIZE];int     Qos;char    method[SIZE] ;char    time[SIZE];char    jsonid[SIZE] ;char    identifier[SIZE] ;char    version[SIZE] ;}mqtt_user_data;int set_config(char *path,char *host,int port, char *clientid,char *uname,char *pwd,char *topic);int get_config(char *path, mqtt_user_data *mqtt, int mode);#endif

[address]
host    =       iot-06z00i99uliom9a.mqtt.iothub.aliyuncs.com
port    =       1883[user_name_pwd]
username    =   ds18b20&gr71iZ9S48c
pwd         =   2a59fde4b9765b403df5bfe7ce63b06cfb79e7d57cb373a0dfa501f79623cc83[clientid]
id          =    gr71iZ9S48c.ds18b20|securemode=2,signmethod=hmacsha256,timestamp=2524608000000|[pub_topic]
topic       =   /sys/gr71iZ9S48c/ds18b20/thing/event/property/post[sub_topic]
topic       =   /sys/gr71iZ9S48c/ds18b20/thing/service/property/set[ali_json]
method      =   thing.service.property.set
id          =   ip    
identifier  =   CurrentTemperature
version     =   1.0.0[KEEP_ALIVE]
alive   =   60[ali_Qos]
Qos     =   0

发布端代码实现

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <libgen.h>
#include <getopt.h>
#include <string.h>
#include <mosquitto.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <signal.h>
#include <time.h>#include "mqtt_conf.h"
#include "cJSON.h"
#include "dictionary.h"
#include "iniparser.h"
#include "ifconfig.h"
#include "db_sqlite3.h"#define  PROG_VERSION "1.0.0"
#define  INI_PATH "./mqtt_aliyun.ini"static int g_stop = 0;/* 调用信号 */
void sig_handler(int sig_num)
{if(sig_num == SIGUSR1)g_stop = 1;}int db_init(sqlite3  *db,char *zErrMsg);
int db_table(char *zErrMsg, sqlite3 *db);
int db_store(sqlite3 *db,char *zErrMsg);
int get_temperature(float *temper);
int get_time (char *datetime,int len);
static inline void print_usage(char *progname);
char *create_json(void *obj);
void connect_callback(struct mosquitto *mosq,void *obj,int rc);int main (int argc, char **argv)
{char                        *progname = basename(argv[0]);int                         brokerport = 1883;char                        *brokeraddress = NULL;char                        *clientid = NULL;char                        *username = NULL;char                        *password = NULL;char                        *topic = NULL;struct mosquitto            *mosq = NULL;int                         daemon_run = 0;int                         opt = -1;int                         rv;int                         log_fd;struct mqtt_user_data       mqtt;struct option options[] = {{"daemon",no_argument,NULL,'d'},{"topic", required_argument,NULL,'t'},{"brokeraddress", required_argument,NULL,'H'},{"clientid", required_argument, NULL, 'i'},{"brokerport",required_argument,NULL,'p'},{"help",no_argument,NULL,'h'},{"username",required_argument,NULL,'u'},{"password",required_argument,NULL,'P'},{NULL,0,NULL,0}};while((opt = getopt_long(argc,argv,"dhp:t:i:u:P:H:",options,NULL)) != -1){switch(opt){case 't':topic = optarg;break;case 'i':clientid = optarg;break;case 'H':brokeraddress = optarg;break;case 'u':username = optarg;break;case 'P':password = optarg;break;case 'd':daemon_run = 1;break;case 'p':brokerport = atoi(optarg);break;case 'h':print_usage(argv[0]);return 0;default:break;}}/* 创建日志 */if(daemon_run){printf("program %s running in backgrund\n", progname);if( (log_fd = open("client.log", O_CREAT|O_RDWR, 0666)) < 0){printf("open() failed:%s\n", strerror(errno)) ;return -2;}dup2(log_fd, STDOUT_FILENO);dup2(log_fd, STDERR_FILENO);daemon(1,1);}/* 安装信号 */signal(SIGUSR1,sig_handler);/* 载入配置文件 */memset(&mqtt,0,sizeof(mqtt));rv = get_config(INI_PATH,&mqtt,PUB);/* MQTT 初始化 */mosquitto_lib_init();/* 创建MQTT 客户端 */mosq = mosquitto_new(mqtt.clientid,true,(void *)&mqtt);if(!mosq){printf("mosquitto_new() failed: %s\n",strerror(errno));goto cleanup;return -1;}/* 设置账号密码 */if(mosquitto_username_pw_set(mosq,mqtt.username,mqtt.password) != MOSQ_ERR_SUCCESS){printf("mosquitto_username_pw_set failed: %s\n",strerror(errno));goto cleanup;}printf("Create mosquitto successfully!\n");/* 回调函数 */mosquitto_connect_callback_set(mosq,connect_callback);while(!g_stop){/* 连接MQTT服务器,ip,端口,时间 */ if(mosquitto_connect(mosq, mqtt.brokeraddress,mqtt.brokerport,KEEP_ALIVE) != MOSQ_ERR_SUCCESS){printf("mosquitto_connect() failed: %s\n",strerror(errno));goto cleanup;}printf("connect successfully\n");/*无阻塞 断线连接 */mosquitto_loop_forever(mosq,-1,1);sleep(3);}/* 释放客户端,清除 */
cleanup:close(log_fd);mosquitto_destroy(mosq);mosquitto_lib_cleanup();return 0;
} /* 帮助信息 */
void print_usage(char *progname)
{printf("%s usage:\n",progname);printf("Example: %s -h ${brokeraddress} -p ${brokerport} -i ${clientid} -u ${username} -p ${password} -t${topic} -h ${help} -d ${daemon}\n",progname);printf("-h(--host): sepcify brokeraddress.\n");printf("-p(--port): sepcify brokerport.\n");printf("-h(--Help): print this help information.\n");printf("-d(--daemon): set program running on background.\n");printf("-i(--clientid): sepcify the clientid.\n");printf("-u(--username): sepcify username of the client.\n");printf("-p(--password): sepcify password of the username.\n");printf("-t(--topic): sepcify topic of the client.\n");printf("-d(--daemon): running in backgrund.\n");
}/* cJSON打包数据 */
void connect_callback(struct mosquitto *mosq,void *obj,int rc)
{char                    ipaddr[16];char                    *interface="eth0";char                    datetime[64];cJSON                   *root;cJSON                   *item;char                    *msg;struct mqtt_user_data   *mqtt;char                    buf[2048];printf("Connection successful cJSON call packaging\n");float temper = 0.00000000;if(get_temperature(&temper) < 0){printf("get_temperature failed.\n");return;}if(get_time(datetime,sizeof(datetime))<0){printf("get_time failure\n");return ;}memset(ipaddr,0,sizeof(ipaddr));if(get_ipaddr(interface,ipaddr,sizeof(ipaddr))<0){printf("ERROR:get ip address failure\n");return ;}snprintf(buf,sizeof(buf),"%s/%s/%f",ipaddr,datetime,temper);sqlite_tem(buf);printf("Data transfer database successfully!\n");printf("\n");root = cJSON_CreateObject();item = cJSON_CreateObject();if(!obj){printf("invalid_argument in %s\n",__FUNCTION__);return;}mqtt = (mqtt_user_data *)obj;cJSON_AddItemToObject(root,"method",cJSON_CreateString(mqtt->method));cJSON_AddItemToObject(root,"id",cJSON_CreateString(ipaddr));cJSON_AddItemToObject(root,"time",cJSON_CreateString(datetime));cJSON_AddItemToObject(root,"params",item);cJSON_AddItemToObject(item,"CurrentTemperature",cJSON_CreateNumber(temper));cJSON_AddItemToObject(root,"version",cJSON_CreateString(mqtt->version));msg = cJSON_Print(root);printf("%s\n",msg);if(!rc){if(mosquitto_publish(mosq,NULL,mqtt->topic,strlen(msg),msg,mqtt->Qos,NULL) != MOSQ_ERR_SUCCESS){printf("mosquitto_publish failed: %s\n",strerror(errno));return;}}mosquitto_disconnect(mosq);}/* 获取温度 */
int get_temperature(float *temper)
{char            w1_path[64] = "/sys/bus/w1/devices/";char            chip[32];char            buf[128];DIR            *dirp;struct dirent  *direntp;int             fd = -1;char           *ptr;int             found = 0;if( !temper ){return -1;}if((dirp = opendir(w1_path)) == NULL){printf("Opendir '%s' error: %s\n", w1_path, strerror(errno));return -2;}while((direntp = readdir(dirp)) != NULL){if(strstr(direntp->d_name,"28-")){strncpy(chip, direntp->d_name, sizeof(chip));found = 1;break;}}closedir(dirp);if( !found ){printf("Can not find ds18b20 in '%s'\n", w1_path);return -3;}strncat(w1_path, chip, sizeof(w1_path)-strlen(w1_path));strncat(w1_path, "/w1_slave", sizeof(w1_path)-strlen(w1_path));if( (fd=open(w1_path, O_RDONLY)) < 0 ) { printf("open %s error: %s\n", w1_path, strerror(errno)); return -4;} if(read(fd, buf, sizeof(buf)) < 0){printf("read %s error: %s\n", w1_path, strerror(errno)); return -5;} ptr = strstr(buf, "t=");if( !ptr ){printf("ERROR: Can not get temperature\n");return -6;}*temper = atof(ptr+=2)/1000;close(fd);return 0;
}/* 获取时间 */
int get_time(char *datime,int len)
{time_t          t;struct tm       *p;time(&t);p = gmtime(&t);snprintf(datime, 32, "%d-%d-%d %d:%d:%d", 1900+p->tm_year,1+p->tm_mon, p->tm_mday, (p->tm_hour + 8), p->tm_min, p->tm_sec);return 0 ;
}

运行结果

可以看到温度在实时更新(我设置睡眠时间短,所有没有显示,温度变化).

项目源码地址