【Linux网络与网络编程】04.TCP Socket编程

一、TCP Socket编程接口

// 创建套接字
int socket(int domain, int type, int protocol);
// 参数：
//		domain：域（协议家族），这里使用 AF_INET 表示进行网络编程
//		type：网络通信传输的类型，这里选择 SOCK_STREAM表示是使用TCP协议的面向数据报传递信息
//		protocol：这个参数目前置0即可
// 返回值：成功则返回一个文件描述符（所以创建套接字的本质就是创建了一个文件）；失败则返回-1，并设置对应的错误码// 填充网络信息并绑定
int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
// 参数：
//		sockfd：套接字文件描述符
//		addr：这是为了统一socket接口而定义的数据结构，其中的 sockaddr_in 是我们今天网络通信所要用到的，我们需要在绑定之前设置好它的协议家族，端口号和ip地址
//		addrlen：这是将addr的大小传递给内核，方便判断是哪种addr
// 返回值：成功返回0；失败则返回-1，并设置对应的错误码// TCP是面向连接的，连接成功后才能进行通信，因此要求TCP要随时随地等待被连接
// 监听
int listen(int sockfd, int backlog);
// 参数：
//		sockfd：被设置为监听状态的sockfd
//		backlog：最大连接个数
// 返回值：成功返回0；失败则返回-1，并设置对应的错误码// 获取新连接
int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
// 参数：
//		sockfd：监听的sockfd
//		addr：请求连接的addr结构
//		addrlen：请求连接的addr结构的大小
// 返回值：成功返回一个用于服务的sockfd；失败则返回-1，并设置对应的错误码// 客户端不需要bind，首次connect是被自动绑定
// 连接
int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
// 参数：
//		sockfd：客户端想要去连接的sockfd
//		addr和addrlen：目标主机的addr结构
// 返回值：成功返回0；失败则返回-1，并设置对应的错误码

二、TCP Socket编程

2.1 EchoSever

这里我们来仿照UDP的Echo写一个EchoSever来快速熟悉接口。

//TCPSever.hpp
#pragma once
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include "InetAddr.hpp"
#include "Log.hpp"using namespace LogMudule;const static uint16_t defaultport = 8888;class TCPSever
{
public:TCPSever(uint16_t port = defaultport) : _addr(port){// 创建套接字int n = _listensockfd = ::socket(AF_INET, SOCK_STREAM, 0);if (n < 0){LOG(LogLevel::FATAL) << "socket failed";exit(1);}LOG(LogLevel::INFO) << "socket succeed";// 绑定n = ::bind(_listensockfd, _addr.NetAddr(), _addr.Len());if (n < 0){LOG(LogLevel::FATAL) << "bind failed";exit(1);}LOG(LogLevel::INFO) << "bind succeed";// 开始监听n = ::listen(_listensockfd, 5);if (n < 0){LOG(LogLevel::FATAL) << "listen failed";exit(1);}LOG(LogLevel::INFO) << "listen succeed";}void Run(){while(true){//获取连接struct sockaddr_in connected_addr;socklen_t len=sizeof(connected_addr);int sockfd=::accept(_listensockfd,(struct sockaddr*)&connected_addr,&len);if(sockfd<0){LOG(LogLevel::ERROR)<<"accept failed";continue;}InetAddr peer(connected_addr);LOG(LogLevel::INFO)<<"accept succeed connected is "<<peer.Addr() <<" sockfd is "<<sockfd;//既然可以获取到信息了，那么下一步就是提供服务了Service(sockfd);//完成之后就要关闭sockfd::close(sockfd);}}~TCPSever() {::close(_listensockfd);}
private:void Service(int sockfd){char buff[1024];while(true){//TCP是面向字节流的，故而可以采用文件的接口进行读取和写入int n=::read(sockfd,buff,sizeof(buff)-1);if(n>0){buff[n]=0;std::string message="Client Say@";message+=buff;int m=::write(sockfd,message.c_str(),message.size());if(m<0) {LOG(LogLevel::ERROR)<<"write failed";}}else if(n==0){//表示读到了文件末尾LOG(LogLevel::INFO)<<"Client Quit……";break;}else{LOG(LogLevel::ERROR)<<"read error";break;}}}private:int _listensockfd;InetAddr _addr;
};

//TCPSever.cc
#include "TCPSever.hpp"
int main()
{std::unique_ptr<TCPSever> ts_ptr=std::make_unique<TCPSever>();ts_ptr->Run();return 0;
}

再来完成我们的客户端代码：

// TCPClient.hpp
#pragma once
#include <string>
#include <unistd.h>
#include <sys/socket.h>
#include "Log.hpp"
#include "InetAddr.hpp"using namespace LogMudule;
const static std::string defaultip="127.0.0.1";
const static int defaultport=8888;class TCPClient
{
public:TCPClient(std::string ip,uint16_t port):_dst_addr({ip,port}){//创建套接字_sockfd=::socket(AF_INET,SOCK_STREAM,0);if(_sockfd<0){LOG(LogLevel::FATAL)<<"socket failed";exit(1);}LOG(LogLevel::INFO)<<"socket succeed";//不需要绑定}void Run(){cout<<_sockfd<<endl;int n=::connect(_sockfd,_dst_addr.NetAddr(),_dst_addr.Len());if(n<0){LOG(LogLevel::ERROR)<<"connect failed";exit(3);}LOG(LogLevel::INFO)<<"connect succeed";while(true){std::string message;std::getline(std::cin,message);cout<<"message is:"<<message<<endl;::write(_sockfd,message.c_str(),message.size());char buff[1024];n=::read(_sockfd,buff,sizeof(buff)-1);if(n>0){buff[n]=0;std::cout<<buff<<std::endl;}}}~TCPClient(){::close(_sockfd);}private:int _sockfd;InetAddr _dst_addr;
};

//TCOClient.cc
#include <memory>
#include "TCPClient.hpp"int main(int argc,char* argv[])
{if(argc!=3){std::cout<<"Usgae Error"<<std::endl;exit(-1);}std::string ip=argv[1];uint16_t port=std::stoi(argv[2]);std::unique_ptr<TCPClient> c_ptr=std::make_unique<TCPClient>(ip,port);c_ptr->Run();return 0;
}

这段客户端的代码我们就写好了，简单的测试过后可以发现是可以的。本篇博客采用telnet来充当客户端进行测试：

可以见得我们的服务端的代码逻辑也是正确的，接下来我们要实现多线程和多进程的EchoSever

进程分离管理：

//……
void Run()
{while (true){// 2. 进程分离版本，子进程执行任务，父进程来进行监听// 获取连接struct sockaddr_in connected_addr;socklen_t len = sizeof(connected_addr);int sockfd = ::accept(_listensockfd, (struct sockaddr *)&connected_addr, &len);if (sockfd < 0){LOG(LogLevel::ERROR) << "accept failed";continue;}InetAddr peer(connected_addr);LOG(LogLevel::INFO) << "accept succeed connected is " << peer.Addr() << " sockfd is " << sockfd;int id = fork();if (id == 0){// 子进程::close(_listensockfd);// 子进程再次创建子进程，子进程返回，避免父进程阻塞，孙子进程为孤儿进程，被OS领养if(fork()>0)    exit(0);Service(sockfd);exit(0);}else{// 父进程::close(sockfd);int rid=::waitpid(id,nullptr,0);if(rid<0){LOG(LogLevel::ERROR) << "waitpid failed";}}}
}
//……

线程分离管理：

//……
// 3. 线程分离管理
struct ThreadData
{int _sockfd;TCPSever *_self;
};
static void *Handler(void *args)
{pthread_detach(pthread_self());ThreadData* data=(ThreadData*)args;data->_self->Service(data->_sockfd);return nullptr;
}
//……
void Run()
{while (true){// 3.线程管理版本的// 获取连接struct sockaddr_in connected_addr;socklen_t len = sizeof(connected_addr);int sockfd = ::accept(_listensockfd, (struct sockaddr *)&connected_addr, &len);if (sockfd < 0){LOG(LogLevel::ERROR) << "accept failed";continue;}InetAddr peer(connected_addr);LOG(LogLevel::INFO) << "accept succeed connected is " << peer.Addr() << " sockfd is " << sockfd;ThreadData* data=new ThreadData;data->_sockfd=sockfd;data->_self=this;pthread_t tid; pthread_create(&tid, nullptr, Handler, data);}
}

线程池管理：

//……
void Run()
{while (true){// 4.线程池管理版本struct sockaddr_in connected_addr;socklen_t len = sizeof(connected_addr);int sockfd = ::accept(_listensockfd, (struct sockaddr *)&connected_addr, &len);if (sockfd < 0){LOG(LogLevel::ERROR) << "accept failed";continue;}InetAddr peer(connected_addr);LOG(LogLevel::INFO) << "accept succeed connected is " << peer.Addr() << " sockfd is " << sockfd;//绑定生成任务task_t task=std::bind(&TCPSever::Service,this,sockfd);ThreadPool<task_t> ::GetInstance()->Enqueue(task);}
}
//……

2.2 远程命令执行

//command.hpp
#pragma once
#include <string>
#include <cstring>
#include "Log.hpp"using namespace LogMudule;class Command
{
public:std::string Excute(const std::string &command){// 相当于pipe + exclFILE *fp = popen(command.c_str(), "r");if (fp == nullptr)return std::string();char buffer[1024];std::string result;while (fgets(buffer, sizeof(buffer), fp)){result += buffer;}pclose(fp);return result;}
};

//TCPSever.hpp
#pragma once
#include <string>
#include <functional>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sys/wait.h>
#include <pthread.h>
#include "InetAddr.hpp"
#include "Log.hpp"
#include "ThreadPool.hpp"using namespace LogMudule;
using namespace ThreadPoolModual;const static uint16_t defaultport = 8888;using task_t = std::function<void()>;
using command_t = std::function<std::string(const std::string)>;class TCPSever
{void Service(int sockfd){char buff[1024];while (true){// TCP是面向字节流的，故而可以采用文件的接口进行读取和写入int n = ::read(sockfd, buff, sizeof(buff) - 1);if (n > 0){//网络传输中以\r\n结尾buff[n-2] = 0;std::string message = _command(buff);int m = ::send(sockfd, message.c_str(), message.size(),0);if (m < 0){LOG(LogLevel::ERROR) << "write failed";}}else if (n == 0){// 表示读到了文件末尾LOG(LogLevel::INFO) << "Client Quit……";break;}else{LOG(LogLevel::ERROR) << "read error";break;}}}public:TCPSever(command_t command, uint16_t port = defaultport) : _command(command), _addr(port){// 创建套接字int n = _listensockfd = ::socket(AF_INET, SOCK_STREAM, 0);if (n < 0){LOG(LogLevel::FATAL) << "socket failed";exit(1);}LOG(LogLevel::INFO) << "socket succeed";// 绑定n = ::bind(_listensockfd, _addr.NetAddr(), _addr.Len());if (n < 0){LOG(LogLevel::FATAL) << "bind failed";exit(1);}LOG(LogLevel::INFO) << "bind succeed";// 开始监听n = ::listen(_listensockfd, 5);if (n < 0){LOG(LogLevel::FATAL) << "listen failed";exit(1);}LOG(LogLevel::INFO) << "listen succeed";}void Run(){while (true){// 4.远程执行任务struct sockaddr_in connected_addr;socklen_t len = sizeof(connected_addr);int sockfd = ::accept(_listensockfd, (struct sockaddr *)&connected_addr, &len);if (sockfd < 0){LOG(LogLevel::ERROR) << "accept failed";continue;}InetAddr peer(connected_addr);LOG(LogLevel::INFO) << "accept succeed connected is " << peer.Addr() << " sockfd is " << sockfd;// 绑定生成任务task_t task = std::bind(&TCPSever::Service, this, sockfd);ThreadPool<task_t>::GetInstance()->Enqueue(task);}}~TCPSever(){::close(_listensockfd);}private:int _listensockfd;InetAddr _addr;command_t _command;
};

三、Windows下的TCP Socket

#include <winsock2.h>
#include <iostream>
#include <string>
#pragma warning(disable : 4996)
#pragma comment(lib, "ws2_32.lib")
std::string serverip = "62.234.18.77"; // 填写你的云服务器 ip
uint16_t serverport = 8888; // 填写你的云服务开放的端口号
int main()
{WSADATA wsaData;int result = WSAStartup(MAKEWORD(2, 2), &wsaData);if (result != 0){std::cerr << "WSAStartup failed: " << result << std::endl;return 1;}SOCKET clientSocket = socket(AF_INET, SOCK_STREAM,IPPROTO_TCP);if (clientSocket == INVALID_SOCKET){std::cerr << "socket failed" << std::endl;WSACleanup();return 1; }sockaddr_in serverAddr;serverAddr.sin_family = AF_INET;serverAddr.sin_port = htons(serverport);serverAddr.sin_addr.s_addr = inet_addr(serverip.c_str());result = connect(clientSocket, (SOCKADDR*)&serverAddr,sizeof(serverAddr));if (result == SOCKET_ERROR){std::cerr << "connect failed" << std::endl;closesocket(clientSocket);WSACleanup();return 1;}while (true){std::string message;std::cout << "Please Enter@ ";std::getline(std::cin, message);if (message.empty()) continue;send(clientSocket, message.c_str(), message.size(), 0);char buffer[1024] = { 0 };int bytesReceived = recv(clientSocket, buffer,sizeof(buffer) - 1, 0);if (bytesReceived > 0){buffer[bytesReceived] = '\0'; // 确保字符串以 null 结尾std::cout << "Received from server: " << buffer <<std::endl;}else{std::cerr << "recv failed" << std::endl;}}closesocket(clientSocket);WSACleanup();return 0;
}

最后附上跨平台测试截图：