Linux手把手教你实现udp服务器的详细过程

cc=g++
.PHONY:all
all:udpClient udpServer
udpClient:udpClient.cc
	$(cc) -o $@ $^ -std=c++11
udpServer:udpServer.cc
	$(cc) -o $@ $^ -std=c++11
.PHONY:clean
clean:
	rm -f udpClient udpServer

namespace Server
{
    class udpServer
    {
    public:
        udpServer() 
        {
        }
        void InitServer()
        {
        }
        void start()
        {
        }
        ~udpServer()
        {
        }
    private:
        //服务器一定要有自己的服务端口号（注意端口号是16位的)
        uint16_t _port;     //端口号
        //实际上一款服务器不建议指明一个IP
        string _ip;    //ip
    };
}

 static const string defaultIp = "0.0.0.0";

 udpServer(const uint16_t& port,const string ip = defaultIp)
            :_port(port)
            ,_ip(ip) 
        {
        }

udpServer(const uint16_t& port,const string ip = defaultIp)
            :_port(port)
            ,_ip(ip)
            ,_sockfd(-1)
        {
        }

 void InitServer()
        {
            //UDP第一步：创建了一个套接字
            _sockfd = socket(AF_INET,SOCK_DGRAM,0);
            if (_sockfd==-1)
            {
                cerr<<"socket error: "<<errno<<" : "<<strerror(errno)<<endl;
                exit(SOCKET_ERROR);
            }
            cout<<"server socket success: "<<" : "<<_sockfd<<endl;
        }

    enum 
    {
       SOCKET_ERROR = 2
    };

            struct sockaddr_in local;  //在栈（用户）上定义了一个结构体变量
            bzero(&local,sizeof(local));
            local.sin_family = AF_INET;
            local.sin_port = htons(_port);  //给别人发消息要将port和ip发送给对方 htons主机转网络序列(port是short类型)
            local.sin_addr.s_addr = inet_addr(_ip.c_str());     //1.string->uint32_t 2.主机转网络，ip是四字节htonl

            int n = bind(_sockfd,(struct sockaddr*)&local,sizeof(local));
            if (n==-1)
            {
                cerr<<"bind error:  "<<errno<<" : "<<strerror(errno)<<endl;
                exit(BIND_ERR);
            }

    enum 
    {
       SOCKET_ERROR = 2
       ,BIND_ERR
    };

static void Usage(string proc)
{
    cout<<"Usage:\n\t"<<proc<<" local_ip local_port\n\n";
}
int main(int argc,char* argv[])
{
    if (argc!=3)
    {
        Usage(argv[0]);
        exit(USAGE_ERR);
    }
    uint16_t port = atoi(argv[2]);
    string ip = argv[1];
    unique_ptr<udpServer> usvr(new udpServer(port,ip));
    usvr->InitServer();
    usvr->start();
    return 0;
}

    enum 
    {
       USAGE_ERR = 1
       ,SOCKET_ERROR
       ,BIND_ERR
    };

local.sin_addr.s_addr = INADDR_ANY; //任意地址绑定才是服务器的真实写法

static void Usage(string proc)
{
    cout<<"Usage:\n\t"<<proc<<" local_port\n\n";
}
int main(int argc,char* argv[])
{
    if (argc!=2)
    {
        Usage(argv[0]);
        exit(USAGE_ERR);
    } 
    uint16_t port = atoi(argv[1]); 
    unique_ptr<udpServer> usvr(new udpServer(handerMessage,port));
    usvr->InitServer();
    usvr->start();
    return 0;
}

static const int gnum = 1024;
void start()
        {
            //服务器的本质实际上就是一个死循环
            char buffer[gnum];
            for (;;)
            {
                struct sockaddr_in peer;
                socklen_t len = sizeof(peer);   //必填
                ssize_t s = recvfrom(_sockfd,buffer,sizeof(buffer)-1,0,(structsockaddr*)&peer,&len); //成功返回字节数
            }
        }

void start()
        {
            //服务器的本质实际上就是一个死循环
            char buffer[gnum];
            for (;;)
            {
                struct sockaddr_in peer;
                socklen_t len = sizeof(peer);   //必填
                ssize_t s = recvfrom(_sockfd,buffer,sizeof(buffer)-1,0,(struct sockaddr*)&peer,&len); //成功返回字节数
                //1.数据是什么？ 2.谁发的
                if (s>0)
                {
                    buffer[s] = 0;
                    string clientip = inet_ntoa(peer.sin_addr);   //1.网络序列 2.int->点分十进制IP
                    uint16_t clientport = ntohs(peer.sin_port);
                    string message = buffer;
                    cout<<clientip<<"["<<clientport<<"]#"<<message<<endl;
                }
            }
        }

namespace Client
{
    class udpClient
    {
    public:
       udpClient(const string& serverip,const uint16_t &serverport)
          :_serverip(serverip)
          ,_serverport(serverport)
       {
       }
       void InitClient()
       {
       }
       void run()
       {
       }
       ~udpClient()
       {
       }
    private:
       string _serverip;
       uint16_t _serverport;
    };
}

#include "udpClient.hpp"
#include <memory>
using namespace Client;
static void Usage(string proc)
{
    cout<<"Usage:\n\t"<<proc<<" server_ip server_port\n\n";
}
//./udpClient server_ip server_port
int main(int argc, char* argv[])
{
    if (argc!=3)
    {
        Usage(argv[0]);
        exit(1);
    }
    string serverip = argv[1];
    uint16_t serverport = atoi(argv[2]);
    unique_ptr<udpClient> ucli(new udpClient(serverip,serverport));
    ucli->InitClient();
    ucli->run();
    return 0;
}

udpClient(const string& serverip,const uint16_t &serverport)
          :_sockfd(-1)
          ,_serverip(serverip)
          ,_serverport(serverport) 
       {
       }

void InitClient()
       {
           // 1.创建socket
           _sockfd = socket(AF_INET,SOCK_DGRAM,0);
           if (_sockfd==-1)
           {
               cerr<<"socket error: "<<errno<<" : "<<strerror(errno)<<endl;
               exit(2);
           }
           cout<<"client socket success: "<<" : "<<_sockfd<<endl;
           //2.  client要不要bind(必须要)，client要不要明确的bind(不需要，不需要程序员自己bind(由OS自动形成端口绑定))
       }

void run()
       {
           struct sockaddr_in server;
           memset(&server,0,sizeof(server));
           server.sin_family = AF_INET;
           server.sin_addr.s_addr = inet_addr(_serverip.c_str());
           server.sin_port = htons(_serverport);
           string message;
           while (!_quit)
           {
              cout<<"Please Enter# ";
              cin>>message;
              sendto(_sockfd,message.c_str(),message.size(),0,(struct sockaddr*)&server,sizeof(server));
           }
       }