发送MQTT包

Question

#include "hw_util.h"
#include "MQTTPacket.h"
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
int main (void) {


    int i;
    float temperatura;
    unsigned char buffer[50];





    MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
    int rc = 0;
    char buf[200];
    int buflen = sizeof(buf);
    MQTTString topicString = MQTTString_initializer;
    char* payload = "I'm Alive";
    int payloadlen = strlen(payload);
    int len = 0;
    data.clientID.cstring = "Testing";
    data.keepAliveInterval = 20;
    data.cleansession=1;
    data.MQTTVersion=3;
    len = MQTTSerialize_connect(buf,buflen,&data);
    topicString.cstring="SampleTopic";
    len += MQTTSerialize_publish(buf + len, buflen - len, 0, 0, 0, 0, topicString, payload, payloadlen);

    printf("Hello world");
    rc = 0;
    while(1)
    {

        ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);







    }
}

我下载了HiveMQ，它是一个代理，正在运行：

2018-03-05 19:28:08,195信息-在地址0.0.0.0和端口1883上启动TCP侦听器

现在我想做的是向这个代理或Putty发送类似“Hello World”之类的内容，或者显示整个MQTT有效负载的内容。C是如何处理这个的？这些文档帮助我理解了发生了什么，但并没有真正帮助我编写C代码，因为我对它还是非常陌生。

Answer 1

这花了一段时间，但我想通了。仍然有很多问题需要解决，但至少它会向本地主机发送一个MQTT（Wireshark approved）数据包。

1. 使用以下库创建MQTT数据包:https://os.mbed.com/teams/MQTT/code/mqttpacket/

使用以下代码：

MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
char buf[200];

MQTTString topicString = MQTTString_initializer;
data.clientID.cstring = "TESTIRAM";
data.keepAliveInterval = 20;
data.cleansession=1;
data.MQTTVersion=3;
len = MQTTSerialize_connect(buf,buflen,&data);
topicString.cstring="ka";
len += MQTTSerialize_publish(buf + len, buflen - len, 0, 0, 0, 0, 
topicString, payload, payloadlen);

#include "hw_util.h"
#include "MQTTPacket.h"
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
char buf[200];
int mysock=0;
char *host = "127.0.0.1";
int port = 1883;
mysock = socket(AF_INET, SOCK_STREAM, 0);

AF_INET指定IPv4，而SOCK_STREAM指定TCP。

使用此：

struct sockaddr_in cliaddr;

int rc = 0;
    //initialize the host address

    memset(&cliaddr, 0, sizeof(cliaddr));
    //specify IPv4 protocol
    /*following includes are necessary for this:#include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>*/
    cliaddr.sin_family = AF_INET;
    //intialize the IP address of the host as "127.0.0.1"
    cliaddr.sin_addr.s_addr = inet_addr(host);
    //initialize the port, 1883
    cliaddr.sin_port = htons(port);
    //client has no bind
    //socket()>connect()->send()<->recv()->close
    int statusConn = connect(mysock,(const struct sockaddr*)&cliaddr,sizeof(cliaddr));
    if(statusConn=0){
        printf("Success!");
    }
    if(statusConn=-1){
        printf("Connect unsuccessful!\n");

1. 通过套接字发送！

while(1)
{
        printf("Sending to hostname %s port %d\n", host, port);
        //infinite loop, sending packets to the specified ASOCKET
        //after sending sleep for 10 seconds
        //sleep uses unistd.h

        printf("Sent packets: ");

        int countSend = send(mysock ,buf,buflen,0);

        printf("%d",countSend);

        printf("\n");
        sleep(10);
}