Linux --TCP协议实现简单的网络通信（中英翻译）

一、什么是TCP协议

1.1 、TCP是传输层的协议，TCP需要连接，TCP是一种可靠性传输协议，TCP是面向字节流的传输协议；

二、TCPserver端的搭建

2.1、我们最终好实现的效果是

客户端在任何时候都能连接到服务端，然后向服务端发送请求，服务端回应客户端的请求；且当客户端向服务端发送请求连接失败时（断网或者服务器故障），会有一个重新连接的状态，在某个时间段内可以不停尝试重新连接；在这里我们把请求和回应请求设计为一个英文翻译，即客户端发送英文，服务端翻译英文并把结果返回给客户端；

2.2 TCPserver第一步创建套接字

2.3、准备数据

2.4、绑定

2.5、监听

以上初始化工作完成，接下来服务器运行：

2.6、获取连接

2.7、让线程池取获取并处理任务

自己实现的简单版的线程池：

#pragma once
// 线程池类实现
#include <iostream>
#include <vector>
#include <queue>
#include <unistd.h>
const static int defaultNum = 5;
struct ThreadInfo
{pthread_t tid_;std::string threadname_;
};
template <class T>
class threadpool
{
public:void lock(){pthread_mutex_lock(&mutex_);}void unlock(){pthread_mutex_unlock(&mutex_);}void wakeup() // 唤醒{pthread_cond_signal(&cond_);}void sleep_t() // 休眠（到条件变量的等待队列里面等）{pthread_cond_wait(&cond_, &mutex_);}bool isempty(){return task_queue.empty();}std::string getThreadname(pthread_t tid){for (auto &e : threads_){if (e.tid_ == tid)return e.threadname_;}return "None";}public:void push(const T &task){lock();task_queue.push(task);wakeup();unlock();}static void *HandlerTask(void *args) // 类内成员函数有this指针，会参数不匹配，加static修饰就没有了{threadpool<T> *tp = static_cast<threadpool<T> *>(args);std::string name=tp->getThreadname(pthread_self());while (true){tp->lock();// 1.获取任务while (tp->isempty()) // 防止伪唤醒{tp->sleep_t();}T t =tp->pop();tp->unlock();// 2.消费任务t();}}void start(){int threadcout = threads_.size();for (int i = 0; i < threadcout; i++){// 创建的同时把线程数组里的数据初始化好threads_[i].threadname_ = "thread-" + std::to_string(i + 1);pthread_create(&(threads_[i].tid_), nullptr, HandlerTask, this); // static成员函数不能访问成员变量，只能通过类对象访问}}T pop(){T out = task_queue.front();task_queue.pop();return out;}static threadpool<T> *GetInstacne() // 获取实例{                                   // 如果有多个线程同时进来获取实例呢？如果不上锁会导致对象被实例化多份出来if (tp_ == nullptr)             // 后面进来的大部分线程都会判断失败，不需要继续往获取锁{// 走到这里的只有一小部分线程pthread_mutex_lock(&lock_); // 上锁if (tp_ == nullptr)         // 只有第一次获取单例的线程需要进行条件判断，后续线程进来判断都失败{tp_ = new threadpool<T>();}pthread_mutex_unlock(&lock_); // 解锁}return tp_;}private:std::vector<ThreadInfo> threads_; // 存放线程信息（通过里面的tid找到线程）std::queue<T> task_queue;              // 存放任务的队列pthread_mutex_t mutex_;           // 访问队列的时候需要上锁pthread_cond_t cond_;             // 如果没有任务就去里面等threadpool(const T &) = delete;   // 把一切可构造出第二个对象的成员函数禁掉const threadpool<T> &operator=(const threadpool<T> &) = delete;threadpool(int threadnum = defaultNum): threads_(threadnum){// 初始化锁跟条件变量pthread_mutex_init(&mutex_, nullptr);pthread_cond_init(&cond_, nullptr);}~threadpool(){// 销毁锁和条件变量pthread_mutex_destroy(&mutex_);pthread_cond_destroy(&cond_);}static threadpool<T> *tp_;static pthread_mutex_t lock_;
};template <class T> // 静态类成员类外定义
threadpool<T> *threadpool<T>::tp_ = nullptr;template <class T>
pthread_mutex_t threadpool<T>::lock_ = PTHREAD_MUTEX_INITIALIZER; // 如果用全局锁需要对锁进行初始化跟销毁

2.8 把Task任务编写一下，即收发任务

#pragma once
#include <string>
#include"Init.hpp"
Init init;
const int buffersize = 1024;
class Task
{
private:int sock_fd;std::string clientip_;uint16_t clientport_;public:Task(const int &fd, const std::string &ip, const uint16_t &port): sock_fd(fd), clientip_(ip), clientport_(port){}void operator()(){Run();}void Run(){char buffer[buffersize];ssize_t n = read(sock_fd, buffer, sizeof(buffer));if (n > 0){buffer[n] = '\0';std::string message = buffer; // 获取client的信息std::string echo_message = init.translation(message);// 2.写// 把获取到的信息进行转换，输出client想要的信息ssize_t w = write(sock_fd, echo_message.c_str(), echo_message.size());if (w < 0){lg(WARNING, "Write fail!!");}else if (w == 0){lg(WARNING, "Read close!!");}}else if (n < 0){lg(INFO, "Read fail!! client ip is:%s, clien port is:%d",clientip_.c_str(),clientport_);}else{lg(WARNING, "Client close!! fd:%d, client ip: %s, client port: %d",sock_fd,clientip_.c_str(),clientport_);}close(sock_fd);}~Task(){}
};

2.9、server的main入口函数

#include "TcpServer.hpp"
#include <memory>
void Usage(std::string proc)
{std::cout<<"\n\rUsage:"<<proc<<" serverport[1024+]"<<std::endl;
}
//server serverport
int main(int argc,char * argv[])
{if(argc!=2){Usage(argv[0]);exit(1);}uint16_t port=std::stoi(argv[1]);lg.Enable(CLASSFILE);std::unique_ptr<TcpServer> ptr(new TcpServer(port));ptr->Init();ptr->Start();return 0;
}

三、客户端的编写

3.1

#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string>
#include <cstdlib>
#include <cstring>
#include <unistd.h>
#define SIZE 1024
void Usage(std::string proc)
{std::cout << "\n\rUsage:" << proc << " serverip serverport" << std::endl;
}
// client serverip serverport
int main(int argc, char *argv[])
{if (argc != 3){Usage(argv[0]);exit(1);}uint16_t serverport = std::stoi(argv[2]);std::string serverip = argv[1];// 2.准备数据struct sockaddr_in server;memset(&server, 0, sizeof(server)); // 初始化结构体server.sin_family = AF_INET;server.sin_port = htons(serverport);inet_pton(AF_INET, serverip.c_str(), &server.sin_addr);// 3.OS自动绑定在第一次连接成功时// 4.发起连接while (true){// 1.创建套接字int sock_fd = socket(AF_INET, SOCK_STREAM, 0);if (sock_fd < 0){return -1;}int cnt = 5;bool isconnect = false;do{ssize_t c = connect(sock_fd, (sockaddr *)&server, sizeof(server));if (c<0){cnt--;isconnect = true;std::cout << "Is connect!! time: " << cnt << std::endl;sleep(2);}else{break;}} while (cnt && isconnect);if (cnt == 0){std::cout << "user offline!!" << std::endl;break;}// 走到这里连接成功// 1.写std::cout << "Please enter@ " << std::endl;std::string line;std::getline(std::cin, line);ssize_t w = write(sock_fd, line.c_str(), line.size());if(w<0){std::cout<<"Write fail!!"<<std::endl;}// 2.读char buffer[SIZE];ssize_t r = read(sock_fd, buffer, sizeof(buffer));if (r > 0){buffer[r] = '\0';std::cout << buffer << std::endl;}close(sock_fd);}return 0;
}

3.2、在server中加入守护进程

守护进程的实现：

#pragma once
#include <unistd.h>
#include<cstdlib>
#include<signal.h>
#include<string>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>std:: string nullfile="/dev/null";
void Deamon(const std::string& cwd="")
{//1.忽略其他异常信号signal(SIGSTOP,SIG_IGN);signal(SIGPIPE,SIG_IGN);signal(SIGCLD,SIG_IGN);//2.自成会话if(fork()>0)exit(0);setsid();//3.更改调用进程的工作目录if(cwd.c_str()!=""){chdir(cwd.c_str());}//4.关闭标准输入输出错误流//打开垃圾桶int fd=open(nullfile.c_str(),O_RDONLY);//只读方式打开if(fd>0){//重定向到垃圾桶dup2(fd,0);dup2(fd,1);dup2(fd,2);}}

3.3、翻译服务的实现

#pragma oce
#include<unordered_map>
#include<fstream>
#include"log.hpp"
extern Log lg;
std::string filename="dict.txt";
std::string separator=":";
static bool split(const std::string&line,std::string*ptr1,std::string*ptr2)
{auto pos=line.find(separator);if(pos!=std::string::npos){*ptr1=line.substr(0,pos);*ptr2=line.substr(pos+1);return true;}return false;
}
class Init
{private:std::unordered_map<std::string,std::string> dict_;public:Init(){std::ifstream in(filename);if(!in.is_open()){lg(FATAL,"Ifstream open fail!!");exit(1);}std::string line;while(getline(in,line)){std::string ptr1,ptr2;split(line,&ptr1,&ptr2);dict_.insert({ptr1,ptr2});}in.close();}std::string translation(std::string&word){auto iter=dict_.find(word);if(iter!=dict_.end()){return iter->second;}return "Unknow";}~Init(){}
};

其中这个字典集随便找的一些内容：

3.4makefile 编译运行

.PHONY:all
all: tcpclient tcpserver
tcpclient:TcpClient.cppg++ -o $@ $^ -std=c++11
tcpserver:Main.cppg++ -o $@ $^ -std=c++11 -lpthread
.PHONY:clean
clean:rm -f tcpserver tcpclient

服务运行只要运行一次起来后有就会7*24小时在后台跑着：