Socket通信实践

以你之姓@ 2022-11-18 04:43 208阅读 0赞

1、获取HostInfo

get\_host\_info.h

#include <arpa/inet.h> 
    #include <netdb.h>    
    #include <unistd.h>   
    
    bool getHostInfo(std::string& host_name, std::string& ip)
    {
        char name[256];
        gethostname(name, sizeof(name));
        host_name = name;
        struct hostent* host = gethostbyname(name);
        char ipStr[32];
        const char* ret =
            inet_ntop(host->h_addrtype, host->h_addr_list[0], ipStr, sizeof(ipStr));
        if (NULL == ret) {
          return false;
        }
        ip = ipStr;
        return true;
    };

2、服务端Server

#include <sys/socket.h> 
    #include <iostream>
    
    #include "get_host_info.h"
    
    int main()
    {
        int port = 9100;
        std::string host_name,ip;
        if(!getHostInfo(host_name,ip)){
            return 0;
        }
    
        //创建套接字，绑定端口，IP
        int server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        struct sockaddr_in server_addr;
        memset(&server_addr, 0, sizeof(server_addr));         
        server_addr.sin_family = AF_INET;                              
        server_addr.sin_addr.s_addr = inet_addr(ip.c_str());            
        server_addr.sin_port = htons(port);                    
        bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr));
    
        //进入监听状态，等待用户发起请求
        if (listen(server_socket, 20)) {return 0;}
    
        //在while循环内等待客户端的链接
        struct sockaddr_in client_addr;
        socklen_t client_addr_size = sizeof(client_addr);
        while(true)
        {
            //接收到客户端套接字,server会持续停留在下面这条语句，直到接收到客户端
            int client_sock = accept(server_socket, (struct sockaddr*)&client_addr, &client_addr_size);
    
            //一次成功链接，考试处理作出反应
            if (client_sock > 0) 
            {
              std::string recv_buffer = "";
              //一次成功链接后，会持续接受该客户端信息，直到客户端关闭，才会失去链接
              while(1)
              {
                //注意client发过来的信息可能很长，会切割成1024大小的片段发送，所以需要多次接受
                char buffer[1024];      
                memset(buffer,0,sizeof(buffer));
                int len = recv(client_sock,buffer,sizeof(buffer),0);
                if(len <= 0)break;
                recv_buffer += std::string(buffer);                  
              }
              if(recv_buffer == ""){continue;}
              //打印接收到的信息
              std::cout<<"receive info : "<<recv_buffer<<std::endl;
              //在这里也可以发送信息给client
            }
            close(client_sock);
        }
        close(server_socket);
        return 0;
    }

3、客户端Client

#include <sys/socket.h> 
    #include <iostream>
    #include <ros/ros.h>
    
    #include "get_host_info.h"
    
    int main()
    {
        //切片发送字符串的lambda函数
        auto sendString = [](int& socket, int step,std::string& send_str)
        {
          //计算待发送数据的长度
          int len = strlen(send_str.c_str());
          //发送数据
          for (int i = 0; i < len; i = i + step) {
            std::string str = send_str.substr(i, step);
            send(socket, str.c_str(), strlen(str.c_str()), 0);
            usleep(1);//中间需要有停顿，不可以一直发送，否则server接受会出现错乱
          }
          //发送一个空字符，server收到长度为0的字符后会停止接收
          std::string str = "";
          send(socket, str.c_str(), strlen(str.c_str()), 0);  
        };
    
        //获取HostInfo
        int port = 9100;
        std::string host_name,ip;
        if(!getHostInfo(host_name,ip)){return 0;}
    
        //在while循环内持续创建套接字，并且发送信息
        while (true) {
          //创建客户端套接字
          int sock = socket(AF_INET, SOCK_STREAM, 0);
          //向服务器（特定的IP和端口）发起请求
          struct sockaddr_in serv_addr;
          memset(&serv_addr, 0, sizeof(serv_addr));           //每个字节都用0填充
          serv_addr.sin_family = AF_INET;                     //使用IPv4地址
          serv_addr.sin_addr.s_addr = inet_addr(ip.c_str());  //具体的IP地址
          serv_addr.sin_port = htons(port);          //端口
    
          //连接服务器
          //connect只会链接一次，不会一直等待
          if (connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
            //std::cout << "can not connect socket" << std::endl;
            // exit(1);
          } else {
            //向server发送信息
            //发送当前的wall time给服务端
            ros::WallTime wall_time = ros::WallTime::now();
            std::string str = std::to_string(wall_time.toSec());
            sendString(sock, 1024, str);
          }
          close(sock);
          sleep(1);
        }  
    }