tcp网络编程（基础）

一.编程前的一些基础

二.tcp网络编程

1.一个服务器只能有一个客户端连接（下面代码）

Socket.hpp

TcpServer.hpp

TcpServerMain.cc

TcpClientMain.cc

2.一个服务器可以有多个客户端连接（多线程）

看这篇文章前，先把有关udp和一些网络基础看了（最好敲一下代码）

网络基础1-CSDN博客

一.编程前的一些基础

1.tcp是面向连接的，面向字节流的，在通信前要先建立连接（将服务端设置为监听状态（listen），服务端等待连接的到来（accept）,客户端主动建立连接（connect），建立连接后就可以通信（send,recv）了）

二.tcp网络编程

1.一个服务器只能有一个客户端连接（下面代码）

Socket.hpp

#pragma once#include<iostream>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include<cstring>
#include<string>
#include <unistd.h>#define Convert(addr) ((struct sockaddr*)addr)enum
{SocketError = 1,BindError,ListenError,
};const static int defaultbackflag = 5;
const int defaultsockfd = -1;//简单解释下：Socket.hpp用了继承，多态的知识
//我们将创建socket，bind, listen, accept, connect等方法都单独封装起来class Socket
{
public:Socket(){}~Socket(){}virtual void CreateSocket() = 0; //创建socket套接字virtual void BindSocket(uint16_t port) = 0; //绑定套接字virtual void ListenSocket(int backflag = defaultbackflag) = 0; //将服务端设置为监听状态virtual Socket* AcceptConnection(std::string *peerip, uint16_t *peerport) = 0; //服务端接收客户端发来的连接请求virtual bool ConnectServer(std::string& serverip, uint16_t serverport) = 0; //客户端准备连接服务端virtual int GetSockfd() = 0; //获取sockfdvirtual void SetSockfd(int sockfd) = 0;virtual void CloseSockfd() = 0; //关闭文件描述符
public://将服务端设置为监听状态 //tcpserver.hpp调用void BuildListenSocketMethod(uint16_t port, int backflag = defaultbackflag){CreateSocket();BindSocket(port);ListenSocket(backflag);}//客户端去连接服务端  //tcpclient.hpp调用bool BuildConnectSocketMethod(std::string& serverip, uint16_t serverport){CreateSocket();return ConnectServer(serverip, serverport);}void BuildNormalSocketMethod(int sockfd){SetSockfd(sockfd);}
};//继承并将具体方法实现
class TcpSocket : public Socket
{
public:TcpSocket(int sockfd = defaultsockfd):_sockfd(sockfd){}void CreateSocket() override{//创建socket套接字//tcp用SOCK_STREAM,_sockfd = socket(AF_INET, SOCK_STREAM, 0);if(_sockfd < 0)//失败{exit(SocketError);}}void BindSocket(uint16_t port) override{//方法同udpstruct sockaddr_in local;local.sin_family = AF_INET;local.sin_port = htons(port);local.sin_addr.s_addr = INADDR_ANY;int n = bind(_sockfd, Convert(&local), sizeof(local)); //绑定本机socketif(n != 0) exit(BindError);}void ListenSocket(int backflag = defaultbackflag) override{//设置服务端为监听状态int n = listen(_sockfd, backflag);if(n != 0) exit(ListenError);}//peerip,peerport是输出型参数，目的是获取有关client的一些信息，并为我们所用Socket* AcceptConnection(std::string* peerip, uint16_t* peerport) override{//client的一些信息struct sockaddr_in peer;socklen_t len = sizeof(peer);//服务端获取客户端的connect请求，进行连接（此函数阻塞等待）//accept成功会返回一个新的文件描述符（>0），我们使用新的文件描述符进行通信int newsockfd = ::accept(_sockfd, Convert(&peer), &len);if(newsockfd < 0) return nullptr;*peerip = inet_ntoa(peer.sin_addr);*peerport = ntohs(peer.sin_port);Socket* s = new TcpSocket(newsockfd);return s;}bool ConnectServer(std::string& serverip, uint16_t serverport) override{//客户端发送连接请求struct sockaddr_in server;memset(&server, 0, sizeof(server));server.sin_family = AF_INET;server.sin_port = htons(serverport);inet_pton(AF_INET, serverip.c_str(), &server.sin_addr); //更安全//或者server.sin_addr.s_addr = inet_addr(serverip.c_str());//失败-1，并且我们发起连接时，client会被os自动地进行bind，我们不需要自己调用bind函数int n = ::connect(_sockfd, Convert(&server), sizeof(server));if(n == 0) return true;else return false;}int GetSockfd() override{return _sockfd;}void SetSockfd(int sockfd) override{_sockfd = sockfd;}void CloseSockfd() override  //关闭文件描述符{if(_sockfd > defaultsockfd) {close(_sockfd);}}private:int _sockfd;
};

TcpServer.hpp

#pragma once#include<iostream>
#include"Socket.hpp"class TcpServer
{
public:TcpServer(uint16_t port) :_port(port), _listensocket(new TcpSocket()){_listensocket->BuildListenSocketMethod(_port, defaultbackflag); //设置为监听状态}void Loop(){char bufferin[1024];std::string peerip;uint16_t peerport;Socket* s = _listensocket->AcceptConnection(&peerip, &peerport); //服务端接收客户端发来的连接请求if(s == nullptr) exit(0);std::cout << "accept success" << std::endl;while(true) //接收client发的信息{ssize_t n = recv(s->GetSockfd(), bufferin, sizeof(bufferin)-1, 0); //接收client发送的信息//ssize_t n = (s->GetSockfd(), bufferin, sizeof(bufferin)-1);if(n > 0){bufferin[n] = 0;std::string ret;ret += peerip;ret += " ";ret += std::to_string(peerport);std::cout << ret << " " << "client say#" << bufferin << std::endl;}else{break;}}}~TcpServer(){delete _listensocket;}
private:int _port;Socket* _listensocket;
};

TcpServerMain.cc

#include<iostream>
#include<memory>
#include"TcpServer.hpp"//./tcpserver 8888
int main(int argc, char* argv[])
{if(argc != 2){std::cout << "Usage:" << "./tcpserver " << "serverport" << std::endl;}uint16_t localport = std::stoi(argv[1]);std::unique_ptr<TcpServer> svr(new TcpServer(localport));svr->Loop();return 0;
}

TcpClientMain.cc


#include<iostream>
#include "Socket.hpp"
//./tcpclient 127.0.0.1 8888
int main(int argc, char* argv[])
{if(argc != 3){std::cout << "Usage:" << "./tcpclient " << "serverip serverport" << std::endl;}std::string serverip = argv[1];uint16_t serverport = std::stoi(argv[2]);Socket* s = new TcpSocket();if(!s->BuildConnectSocketMethod(serverip, serverport)) //向服务端申请建立连接{std::cerr << "connect " << serverip << ":" << serverport << " failed" << std::endl;}std::cout << "connect " << serverip << ":" << serverport << " success" << std::endl;std::string buffer;while(true)//发信息给服务端{std::getline(std::cin, buffer);std::cout << "Enter:" << std::endl;ssize_t n = send(s->GetSockfd(), buffer.c_str(), buffer.size(), 0); //向服务端发送信息//ssize_t n = write(s->GetSockfd(), buffer.c_str(), buffer.size());if(n < 0){break;}}s->CloseSockfd();return 0;
}