Linux网络编程之TCP

1、TCP协议的简单认识

• 传输层协议

• 有连接

• 可靠传输

• 面向字节流

2、TCP网络编程接口

2.1、socket

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>

int socket(int domain, int type, int protocol);

该接口和UDP一样，首先我们得先创建socket套接字。

用法不一样的是传入参数不同。

UDP传入的type是SOCK_DGRAM，表示无连接不可靠数据报的传输层协议。

那TCP传入的type是SOCK_STREAM，表示有序、可靠、有连接字节流的传输层协议。

2.2、bind

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>

int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);

和UDP的用法一致。

绑定本地服务器信息。

2.3、listen

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>

int listen(int sockfd, int backlog);

这个接口是UDP没有的。

listen接口是监听是否有客户端发器连接，如果有，则给accept接口说可以建立连接。

2.4、accept

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

这个接口是UDP没有的。

accept接口是和客户端建立连接，成功建立连接则返回一个新的文件描述符！

这里举一个生活例子来说明listen和accept的关系：

假设有一家饭馆，有一个招揽客人的服务员张三，还有多个带客人进饭店某个桌子的服务员李四王五等。服务员张三只负责招揽客人，如果有客人想进来吃饭，那么张三就会叫李四王五等服务员带客人去指定桌子吃饭，然后张三再继续招揽客人，李四王五等人只管服务他们带进来的指定客人，知道他们吃完。当然客人进饭店了看了环境可能不想吃了，然后又不吃了。那么这里的张三就是listen，李四王五等人就是accept后的新文件描述符newsockfd1，newsockfd2等。

2.5、connect

#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>

int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);

这个接口是UDP没有的。

connect是客户端向服务器发起连接的接口。

3、简单的TCP网络程序

3.1、服务器响应程序

和UDP服务器响应程序一样，客户端发什么就回什么，只不过多了建立连接的步骤。
注意：在TcpServer.hpp文件中，有处理任务的多个版本。

• Comm.hpp文件

#pragma once
#include "InetAddr.hpp"

enum errorcode
{
   CREATE_ERROR = 1,
   BIND_ERROR,
   LISTEN_ERROR,
   SEND_ERROR,
   RECV_ERROR,
   CONNECT_ERROR,
   FORK_ERROR,
   USAGE_ERROR
};

#define CONV(ADDR) ((struct sockaddr *)ADDR)

std::string CombineIpAndPort(InetAddr addr)
{
   return "[" + addr.Ip() + ":" + std::to_string(addr.Port()) + "] ";
}

• InetAddr.hpp文件

#pragma once

#include <iostream>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string>

class InetAddr
{
   void GetAddress(std::string *ip, uint16_t *port)
   {
       // char *inet_ntoa(struct in_addr in);
       *ip = inet_ntoa(_addr.sin_addr);
       *port = ntohs(_addr.sin_port);
   }

public:
   InetAddr(const struct sockaddr_in &addr) : _addr(addr)
   {
       GetAddress(&_ip, &_port);
   }

   std::string Ip()
   {
       return _ip;
   }

   uint16_t Port()
   {
       return _port;
   }
   bool operator==(InetAddr &addr)
   {
       return _ip == addr.Ip() && _port == addr.Port();
   }

   const struct sockaddr_in& GetAddr()
   {
       return _addr;
   }

   ~InetAddr() {}

private:
   struct sockaddr_in _addr;
   std::string _ip;
   uint16_t _port;
};

• LockGuard.hpp文件

# pragma once

#include <pthread.h>


class LockGuard
{
public:
   LockGuard(pthread_mutex_t *mutex) : _mutex(mutex)
   {
       pthread_mutex_lock(_mutex); // 构造加锁
   }
   ~LockGuard()
   {
       pthread_mutex_unlock(_mutex); // 析构解锁
   }

private:
   pthread_mutex_t *_mutex;
};

• Log.hpp文件

#pragma once

#include <string>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include <stdarg.h>
#include <sys/types.h>
#include "LockGuard.hpp"

using namespace std;

bool isSave = false; // 默认向显示器打印
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
#define FILEPATH "./log.txt"

enum level
{
   DEBUG = 0,
   INFO,
   WARNING,
   ERROR,
   FATAL
};

void SaveToFile(const string &message)
{
   ofstream out(FILEPATH, ios_base::app);
   if (!out.is_open())
       return;
   out << message;
   out.close();
}

std::string LevelToString(int level)
{
   switch (level)
   {
   case DEBUG:
       return "Debug";
   case INFO:
       return "Info";
   case WARNING:
       return "Warning";
   case ERROR:
       return "Error";
   case FATAL:
       return "Fatal";
   default:
       return "Unknow";
   }
}

std::string GetTimeString()
{
   time_t curr_time = time(nullptr);
   struct tm *format_time = localtime(&curr_time);
   if (format_time == nullptr)
       return "None";
   char buff[1024];
   snprintf(buff, sizeof(buff), "%d-%d-%d %d:%d:%d",
            format_time->tm_year + 1900,
            format_time->tm_mon + 1,
            format_time->tm_mday,
            format_time->tm_hour,
            format_time->tm_min,
            format_time->tm_sec);
   return buff;
}

void LogMessage(const std::string filename, int line, bool issave, int level, const char *format, ...)
{
   std::string levelstr = LevelToString(level);
   std::string timestr = GetTimeString();
   pid_t pid = getpid();

   char buff[1024];
   va_list arg;
   // int vsnprintf(char *str, size_t size, const char *format, va_list ap); // 使用可变参数
   va_start(arg, format);
   vsnprintf(buff, sizeof(buff), format, arg);
   va_end(arg);

   LockGuard lock(&mutex);
   std::string message = "[" + timestr + "]" + "[" + levelstr + "]" + "[pid:" + std::to_string(pid) + "]" + "[" + filename + "]" + "[" + std::to_string(line) + "] " + buff + '\n';
   if (issave == false)
       std::cout << message;
   else
       SaveToFile(message);
}

// 固定文件名和行数
#define LOG(level, format, ...)                                               \
   do                                                                        \
   {                                                                         \
       LogMessage(__FILE__, __LINE__, isSave, level, format, ##__VA_ARGS__); \
   } while (0)

#define EnableScreen()  \
   do                  \
   {                   \
       isSave = false; \
   } while (0)

#define EnableFile()   \
   do                 \
   {                  \
       isSave = true; \
   } while (0)

void Test(int num, ...)
{
   va_list arg;
   va_start(arg, num);
   while (num--)
   {
       int data = va_arg(arg, int);
       std::cout << data << " ";
   }
   std::cout << std::endl;
   va_end(arg);
}

• Main.cc文件

#include <iostream>
#include <memory>
#include "TcpServer.hpp"

void Usage()
{
   // printf("./udp_server serverip serverport\n");
   printf("Usage : ./udp_server serverport\n"); // ip 已经设置为0
}

int main(int argc, char *argv[])
{
   // if (argc != 3)
   if (argc != 2)
   {
       Usage();
       exit(USAGE_ERROR);
   }

   uint16_t serverport = std::stoi(argv[1]);
   std::unique_ptr<TcpServer> tsvr = std::make_unique<TcpServer>(serverport);
   tsvr->InitServer();
   tsvr->Start();

   return 0;
}

• Makefile文件

.PHONY:all
all:tcp_client tcp_server

tcp_client:TcpClient.cc
	g++ -o $@ $^ -std=c++14 -lpthread
tcp_server:Main.cc
	g++ -o $@ $^ -std=c++14 -lpthread

.PHONY:clean
clean:
	rm -f tcp_server tcp_client

• TcpClient.cc文件

#include <iostream>

#include <strings.h>
#include <string.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "Comm.hpp"
#include "Log.hpp"

void Usage()
{
   printf("Usage : ./udp_client serverip serverport\n");
}
int main(int argc, char *argv[])
{
   if (argc != 3)
   {
       Usage();
       exit(USAGE_ERROR);
   }
   std::string serverip = argv[1];
   uint16_t serverport = std::stoi(argv[2]);

   int sockfd = socket(AF_INET, SOCK_STREAM, 0);
   if (sockfd < 0)
   {
       LOG(FATAL, "create sockfd error, error code : %d, error string : %s", errno, strerror(errno));
       exit(CREATE_ERROR);
   }
   LOG(INFO, "create sockfd success");

   struct sockaddr_in local;
   bzero(&local, sizeof(local));
   local.sin_family = AF_INET;
   local.sin_port = htons(serverport);
   local.sin_addr.s_addr = inet_addr(serverip.c_str());

   // 发起连接
   int n = ::connect(sockfd, CONV(&local), sizeof(local));
   if (n < 0)
   {
       LOG(WARNING, "create connect error, error code : %d, error string : %s", errno, strerror(errno));
       exit(CONNECT_ERROR);
   }
   LOG(INFO, "create connect success");

   // 发收数据
   while (true)
   {
       std::cout << "Please Enter# ";
       // 发送数据
       std::string message;
       std::getline(cin, message);

       int ret = ::send(sockfd, message.c_str(), message.size(), 0);
       if (ret < 0)
       {
           LOG(FATAL, "send message error, error code : %d, error string : %s", errno, strerror(errno));
           exit(SEND_ERROR);
       }

       char buff[1024];
       // 接收数据
       int m = ::recv(sockfd, buff, sizeof(buff) - 1, 0);
       if (m > 0)
       {
           buff[m] = 0;
           std::cout << "Server Echo$ " << buff << std::endl;
       }
   }
}

• TcpServer.hpp文件

#pragma once

#include <sys/types.h> /* See NOTES */
#include <sys/wait.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include <error.h>
#include <string.h>
#include <pthread.h>
#include <functional>

#include "Log.hpp"
#include "InetAddr.hpp"
#include "Comm.hpp"
#include "Threadpool.hpp"

const int defaultsockfd = -1;
int gbacklog = 16; // 暂时先用

using task_t = std::function<void()>;

// 声明
class TcpServer;

class ThreadData
{
public:
   ThreadData(int sockfd, InetAddr addr, TcpServer *self)
       : _sockfd(sockfd), _addr(addr), _self(self) {}
   ~ThreadData() = default;

public:
   int _sockfd;
   InetAddr _addr;
   TcpServer *_self;
};

class TcpServer
{
public:
   TcpServer(uint16_t port) : _port(port), _listensock(defaultsockfd), _isrunning(false)
   {
   }

   void InitServer()
   {
       // 创建
       _listensock = socket(AF_INET, SOCK_STREAM, 0); // 这个就是文件描述符
       if (_listensock < 0)
       {
           LOG(FATAL, "create sockfd error, error code : %d, error string : %s", errno, strerror(errno));
           exit(CREATE_ERROR);
       }
       LOG(INFO, "create sockfd success");

       struct sockaddr_in local;
       bzero(&local, sizeof(local));
       local.sin_family = AF_INET;
       local.sin_port = htons(_port);
       local.sin_addr.s_addr = INADDR_ANY;
       // 绑定
       int n = ::bind(_listensock, CONV(&local), sizeof(local));
       if (n < 0)
       {
           LOG(FATAL, "bind sockfd error, error code : %d, error string : %s", errno, strerror(errno));
           exit(BIND_ERROR);
       }
       LOG(INFO, "bind sockfd success");
   }

   void Service(int sockfd, InetAddr client)
   {
       while (true)
       {
           // TCP是字节流（可以使用write和read接口），UDP是数据报
           char buff[1024];
           // 接收消息
           int n = ::read(sockfd, buff, sizeof(buff)); // bug，接收数据可能收到的不完整，比如1+100，可能先收到1+1，再收到00 -- 按序到达
           std::string clientAddr = CombineIpAndPort(client);

           if (n > 0)
           {
               buff[n] = 0;
               std::string message = clientAddr + buff;
               LOG(INFO, "get message : \n %s", message.c_str());

               // 发送消息
               int m = ::write(sockfd, buff, strlen(buff)); 
               if (m < 0)
               {
                   LOG(FATAL, "send message error ,error code : %d , error string : %s", errno, strerror(errno));
                   exit(SEND_ERROR);
               }
           }
           else if (n == 0)
           {
               // 发送端不发送数据了
               LOG(INFO, "%s quit", clientAddr.c_str());
               break;
           }
           else
           {
               LOG(FATAL, "recv message error ,error code : %d , error string : %s", errno, strerror(errno));
               exit(RECV_ERROR);
           }
       }
       ::close(sockfd); // 服务结束，关闭文件描述符，避免文件描述符泄漏
   }

   static void *HandlerService(void *args)
   {
       pthread_detach(pthread_self()); // 分离线程
       ThreadData *td = static_cast<ThreadData *>(args);
       td->_self->Service(td->_sockfd, td->_addr);
       delete td;
       return nullptr;
   }

   void Start()
   {
       _isrunning = true;
       while (_isrunning)
       {
           // 监听
           int ret = ::listen(_listensock, gbacklog);
           if (ret < 0)
           {
               LOG(FATAL, "listen error, error code : %d , error string : %s", errno, strerror(errno));
               exit(LISTEN_ERROR);
           }
           LOG(INFO, "listen success!");

           struct sockaddr_in peer;
           socklen_t len = sizeof(peer);
           // 获取新连接
           int sockfd = accept(_listensock, CONV(&peer), &len); // 建立连接成功，创建新文件描述符进行通信
           if (sockfd < 0)
           {
               LOG(WARNING, "accept error, error code : %d , error string : %s", errno, strerror(errno));
               continue;
           }
           LOG(INFO, "accept success! new sockfd : %d", sockfd);

           InetAddr addr(peer); // 给后面提供传入的ip、port
           // 服务 -- 发送和接收数据
           // V0 -- 单进程
           // Service(sockfd, addr); // 这里是while死循环，没有运行完就一直运行，下一个请求来的时候得这个while退出才能执行

           // v1 -- 多进程
           // int id = fork();
           // if (id == 0)
           // {
           //     // 子进程
           //     ::close(_listensock); // 子进程对监听文件描述符不关心
           //     if (fork() > 0)
           //         exit(0);           // 子进程创建进程后退出，孙子进程被系统领养，不用等待
           //     Service(sockfd, addr); // 孙子进程执行任务
           //     exit(0);
           // }
           // else if (id > 0)
           // {
           //     ::close(sockfd); // 这里每次关闭的文件描述符都是4，使得每次accept创建的文件描述符都是4，这个4是留个各个子进程（子进程再给孙子进程）的（互不影响）
           //     // 父进程
           //     pid_t rid = waitpid(id, nullptr, 0); // 虽然是阻塞等待，但是子进程是刚创建就退出来了，让孙子进程（孤儿进程）执行任务，接下来继续监听和建立连接
           //     if (rid == id)
           //     {
           //         LOG(INFO, "wait child process success");
           //     }
           // }
           // else
           // {
           //     // 异常
           //     LOG(FATAL, "fork error ,error code : %d , error string : %s", errno, strerror(errno));
           //     exit(FORK_ERROR);
           // }

           // v2 -- 多线程
           // pthread_t tid;
           // ThreadData *td = new ThreadData(sockfd, addr, this); // 传指针
           // pthread_create(&tid, nullptr, HandlerService, td); // 这里创建线程后，线程去做执行任务，主线程继续向下执行 , 并且线程不能关闭sockf，线程和进程共享文件描述符表

           // v3 -- 线程池
           task_t t = std::bind(&TcpServer::Service, this, sockfd, addr);
           Threadpool<task_t>::GetInstance()->Enqueue(t);

           // v4 -- 进程池 -- 不推荐，需要传递文件描述符！
       }
       _isrunning = false;
   }

   ~TcpServer()
   {
       if (_listensock > defaultsockfd)
           ::close(_listensock); // 不用了关闭监听
   }

private:
   uint16_t _port;
   int _listensock;
   bool _isrunning;
};

• Thread.hpp文件

#ifndef __THREAD_HPP__
#define __THREAD_HPP__

#include <iostream>
#include <string>
#include <unistd.h>
#include <functional>
#include <pthread.h>

using namespace std;

// 封装Linux线程
namespace ThreadModule
{
   using func_t = function<void(string &)>;
   class Thread
   {
   public:
       // /* ThreadData* */Thread(func_t<T> func, T data, const string& name = "default name") : _func(func), _data(data), _threadname(name), _stop(true) {}
       Thread(func_t func, const string &name = "default name") : _func(func), _threadname(name), _stop(true) {}

       void Execute()
       {
           _func(_threadname);

           // _func(_data);
       }

       //  隐含this
       static void *threadroutine(void *arg)
       {
           Thread *self = static_cast<Thread *>(arg);
           self->Execute(); // static 访问不了成员变量
           return nullptr;
       }
       bool Start()
       {
           int n = pthread_create(&_tid, nullptr, threadroutine, this);
           if (!n)
           {
               _stop = false;
               return true;
           }
           else
           {
               return false;
           }
       }

       void Detach()
       {
           if (!_stop)
           {
               pthread_detach(_tid);
           }
       }

       void Join()
       {
           if (!_stop)
           {
               pthread_join(_tid, nullptr);
           }
       }

       string name()
       {
           return _threadname;
       }

       void Stop()
       {
           _stop = true;
       }
       // ~Thread() {}

   private:
       pthread_t _tid;
       string _threadname;
       func_t _func;
       bool _stop;
   };

} // namespace ThreadModule

#endif

• Threadpool.hpp文件

#pragma once

#include <vector>
#include <queue>
#include <queue>
#include "Thread.hpp"
#include <pthread.h>
#include "LockGuard.hpp"

using namespace ThreadModule;

const int NUM = 3;

template <typename T>
class Threadpool
{
   void LockQueue(pthread_mutex_t &mutex)
   {
       pthread_mutex_lock(&mutex);
   }

   void UnLockQueue(pthread_mutex_t &mutex)
   {
       pthread_mutex_unlock(&mutex);
   }

   void SleepThread(pthread_cond_t &cond, pthread_mutex_t &mutex)
   {
       pthread_cond_wait(&cond, &mutex);
   }
   void WakeUpThread(pthread_cond_t &cond)
   {
       pthread_cond_signal(&cond);
   }
   void WakeUpAll(pthread_cond_t &cond)
   {
       pthread_cond_broadcast(&_cond);
   }
   Threadpool(const int threadnum = NUM) : _threadnum(threadnum), _waitnum(0), _isrunning(false)
   {
       pthread_mutex_init(&_mutex, nullptr);
       pthread_cond_init(&_cond, nullptr);
       LOG(INFO, "Threadpool Constructor successful ! ");
   }

   void TaskHandler(string &name)
   {
       // sleep(1);
       // cout  << name << " : hh " << endl;
       // sleep(1);
       LOG(DEBUG, "%s is running", name.c_str());
       while (true)
       {
           LockQueue(_mutex);
           while (_task_queue.empty() && _isrunning)
           {
               // 等待
               ++_waitnum;
               SleepThread(_cond, _mutex);
               --_waitnum;
           }
           // 此时一定大于一个线程没有休眠
           if (_task_queue.empty() && !_isrunning)
           {
               // 此时任务队列已经没有内容，且此时线程池已经停止
               UnLockQueue(_mutex);
               cout << name << " quit ... " << endl;
               break;
           }
           LOG(DEBUG, "%s get task sucessful !", name.c_str());
           //  其他情况就得处理任务
           T t = _task_queue.front();
           _task_queue.pop();
           UnLockQueue(_mutex);

           // 处理任务
           t();
           // cout << name << " : " << t.stringResult() << endl;
           // LOG(DEBUG, "%s handler task sucessful ! Result is %s", name.c_str(), t.stringResult().c_str());
           sleep(1);
       }
   }
   void InitThreadPool()
   {
       for (int i = 0; i < _threadnum; ++i)
       {
           string name = "Thread - " + to_string(i + 1);
           _threads.emplace_back(bind(&Threadpool::TaskHandler, this, placeholders::_1), name);
       }
       _isrunning = true;
       LOG(INFO, "Init Threadpool successful !");
   }

public:
   static Threadpool<T> *GetInstance(int threadnum = NUM)
   {

       if (_instance == nullptr)
       {
           LockGuard lockguard(&_lock);
           if (_instance == nullptr)
           {
               // pthread_mutex_lock(&_lock);
               // 第一次创建线程池
               _instance = new Threadpool<T>(threadnum);
               _instance->InitThreadPool();
               _instance->Start();
               LOG(DEBUG, "第一次创建线程池");
               // pthread_mutex_unlock(&_lock);
               return _instance;
           }
       }

       LOG(DEBUG, "获取线程池");
       return _instance;
   }

   bool Enqueue(const T &in)
   {
       bool ret = false;
       LockQueue(_mutex);
       if (_isrunning)
       {
           _task_queue.push(in);
           if (_waitnum > 0)
               WakeUpThread(_cond);
           LOG(DEBUG, "enqueue sucessful...");
           ret = true;
       }

       UnLockQueue(_mutex);
       return ret;
   }

   void Stop()
   {
       LockQueue(_mutex);
       _isrunning = false;
       if (_waitnum > 0)
           WakeUpAll(_cond);
       UnLockQueue(_mutex);
   }

   void Start()
   {
       for (auto &thread : _threads)
       {
           thread.Start();
           LOG(INFO, "%s is start sucessful...", thread.name().c_str());
       }
   }

   void Wait()
   {
       for (auto &thread : _threads)
       {
           thread.Join();
           LOG(INFO, "%s is quit...", thread.name().c_str());
       }
   }
   ~Threadpool()
   {
       pthread_mutex_destroy(&_mutex);
       pthread_cond_destroy(&_cond);
       LOG(INFO, "delete mutex sucessful !");
   }

private:
   vector<Thread> _threads;
   queue<T> _task_queue;
   int _threadnum;
   int _waitnum;

   pthread_mutex_t _mutex; // 互斥访问任务队列
   pthread_cond_t _cond;

   bool _isrunning;

   // 懒汉模式
   static Threadpool<T> *_instance;
   static pthread_mutex_t _lock;
};

template <typename T>
Threadpool<T> *Threadpool<T>::_instance = nullptr;
template <typename T>
pthread_mutex_t Threadpool<T>::_lock = PTHREAD_MUTEX_INITIALIZER;

• 运行结果：

3.2、服务器执行命令行

• Comm.hpp文件

#pragma once
#include "InetAddr.hpp"

enum errorcode
{
   CREATE_ERROR = 1,
   BIND_ERROR,
   LISTEN_ERROR,
   SEND_ERROR,
   RECV_ERROR,
   CONNECT_ERROR,
   FORK_ERROR,
   USAGE_ERROR
};

#define CONV(ADDR) ((struct sockaddr *)ADDR)

std::string CombineIpAndPort(InetAddr addr)
{
   return "[" + addr.Ip() + ":" + std::to_string(addr.Port()) + "] ";
}

• CommandExecute.hpp文件

#pragma once

#include <stdio.h>
#include <string>
#include <vector>

bool CheckCommand(std::string command)
{
   std::vector<std::string> cmd = {
       "kill",
       "rm",
       "dd",
       "top",
       "reboot",
       "shutdown",
       "mv",
       "cp",
       "halt",
       "unlink",
       "exit",
       "chmod"};
   for (auto &e : cmd)
   {
       if (command.find(e) != std::string::npos)
           return false;
   }

   return true;
}

std::string OnCommand(std::string command)
{
   if (!CheckCommand(command))
   {
       return "bad man!";
   }
   // FILE *popen(const char *command, const char *type);
   FILE *pp = popen(command.c_str(), "r");
   if (!pp)
   {
       return "popen error!";
   }

   std::string response;
   char buff[1024];
   while (true)
   {
       // char *fgets(char *s, int size, FILE *stream);
       char *s = fgets(buff, sizeof(buff), pp);
       if (!s)
           break;
       else
           response += buff;
   }
   pclose(pp);
   return response.empty() ? "not command" : response;
}

• InetAddr.hpp文件

#pragma once

#include <iostream>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string>

class InetAddr
{
   void GetAddress(std::string *ip, uint16_t *port)
   {
       // char *inet_ntoa(struct in_addr in);
       *ip = inet_ntoa(_addr.sin_addr);
       *port = ntohs(_addr.sin_port);
   }

public:
   InetAddr(const struct sockaddr_in &addr) : _addr(addr)
   {
       GetAddress(&_ip, &_port);
   }

   std::string Ip()
   {
       return _ip;
   }

   uint16_t Port()
   {
       return _port;
   }
   bool operator==(InetAddr &addr)
   {
       return _ip == addr.Ip() && _port == addr.Port();
   }

   const struct sockaddr_in& GetAddr()
   {
       return _addr;
   }

   ~InetAddr() {}

private:
   struct sockaddr_in _addr;
   std::string _ip;
   uint16_t _port;
};

• LockGuard.hpp文件

# pragma once

#include <pthread.h>


class LockGuard
{
public:
   LockGuard(pthread_mutex_t *mutex) : _mutex(mutex)
   {
       pthread_mutex_lock(_mutex); // 构造加锁
   }
   ~LockGuard()
   {
       pthread_mutex_unlock(_mutex); // 析构解锁
   }

private:
   pthread_mutex_t *_mutex;
};

• Log.hpp文件

#pragma once

#include <string>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include <stdarg.h>
#include <sys/types.h>
#include "LockGuard.hpp"

using namespace std;

bool isSave = false; // 默认向显示器打印
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
#define FILEPATH "./log.txt"

enum level
{
   DEBUG = 0,
   INFO,
   WARNING,
   ERROR,
   FATAL
};

void SaveToFile(const string &message)
{
   ofstream out(FILEPATH, ios_base::app);
   if (!out.is_open())
       return;
   out << message;
   out.close();
}

std::string LevelToString(int level)
{
   switch (level)
   {
   case DEBUG:
       return "Debug";
   case INFO:
       return "Info";
   case WARNING:
       return "Warning";
   case ERROR:
       return "Error";
   case FATAL:
       return "Fatal";
   default:
       return "Unknow";
   }
}

std::string GetTimeString()
{
   time_t curr_time = time(nullptr);
   struct tm *format_time = localtime(&curr_time);
   if (format_time == nullptr)
       return "None";
   char buff[1024];
   snprintf(buff, sizeof(buff), "%d-%d-%d %d:%d:%d",
            format_time->tm_year + 1900,
            format_time->tm_mon + 1,
            format_time->tm_mday,
            format_time->tm_hour,
            format_time->tm_min,
            format_time->tm_sec);
   return buff;
}

void LogMessage(const std::string filename, int line, bool issave, int level, const char *format, ...)
{
   std::string levelstr = LevelToString(level);
   std::string timestr = GetTimeString();
   pid_t pid = getpid();

   char buff[1024];
   va_list arg;
   // int vsnprintf(char *str, size_t size, const char *format, va_list ap); // 使用可变参数
   va_start(arg, format);
   vsnprintf(buff, sizeof(buff), format, arg);
   va_end(arg);

   LockGuard lock(&mutex);
   std::string message = "[" + timestr + "]" + "[" + levelstr + "]" + "[pid:" + std::to_string(pid) + "]" + "[" + filename + "]" + "[" + std::to_string(line) + "] " + buff + '\n';
   if (issave == false)
       std::cout << message;
   else
       SaveToFile(message);
}

// 固定文件名和行数
#define LOG(level, format, ...)                                               \
   do                                                                        \
   {                                                                         \
       LogMessage(__FILE__, __LINE__, isSave, level, format, ##__VA_ARGS__); \
   } while (0)

#define EnableScreen()  \
   do                  \
   {                   \
       isSave = false; \
   } while (0)

#define EnableFile()   \
   do                 \
   {                  \
       isSave = true; \
   } while (0)

void Test(int num, ...)
{
   va_list arg;
   va_start(arg, num);
   while (num--)
   {
       int data = va_arg(arg, int);
       std::cout << data << " ";
   }
   std::cout << std::endl;
   va_end(arg);
}

• Main.cc文件

#include <iostream>
#include <memory>

#include "TcpServer.hpp"
#include "CommandExecute.hpp"

void Usage()
{
   // printf("./udp_server serverip serverport\n");
   printf("Usage : ./udp_server serverport\n"); // ip 已经设置为0
}

int main(int argc, char *argv[])
{
   // if (argc != 3)
   if (argc != 2)
   {
       Usage();
       exit(USAGE_ERROR);
   }

   uint16_t serverport = std::stoi(argv[1]);
   std::unique_ptr<TcpServer> tsvr = std::make_unique<TcpServer>(serverport, OnCommand);
   tsvr->InitServer();
   tsvr->Start();

   return 0;
}

• Makefile文件

.PHONY:all
all:tcp_client tcp_server

tcp_client:TcpClient.cc
	g++ -o $@ $^ -std=c++14 -lpthread
tcp_server:Main.cc
	g++ -o $@ $^ -std=c++14 -lpthread

.PHONY:clean
clean:
	rm -f tcp_server tcp_client

• TcpClient.cc文件

#include <iostream>

#include <strings.h>
#include <string.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "Comm.hpp"
#include "Log.hpp"

void Usage()
{
   printf("Usage : ./udp_client serverip serverport\n");
}
int main(int argc, char *argv[])
{
   if (argc != 3)
   {
       Usage();
       exit(USAGE_ERROR);
   }
   std::string serverip = argv[1];
   uint16_t serverport = std::stoi(argv[2]);

   int sockfd = socket(AF_INET, SOCK_STREAM, 0);
   if (sockfd < 0)
   {
       LOG(FATAL, "create sockfd error, error code : %d, error string : %s", errno, strerror(errno));
       exit(CREATE_ERROR);
   }
   LOG(INFO, "create sockfd success");

   struct sockaddr_in local;
   bzero(&local, sizeof(local));
   local.sin_family = AF_INET;
   local.sin_port = htons(serverport);
   local.sin_addr.s_addr = inet_addr(serverip.c_str());

   // 发起连接
   int n = ::connect(sockfd, CONV(&local), sizeof(local));
   if (n < 0)
   {
       LOG(WARNING, "create connect error, error code : %d, error string : %s", errno, strerror(errno));
       exit(CONNECT_ERROR);
   }
   LOG(INFO, "create connect success");

   // 发收数据
   while (true)
   {
       std::cout << "Please Enter# ";
       // 发送数据
       std::string message;
       std::getline(cin, message);

       int ret = ::send(sockfd, message.c_str(), message.size(), 0);
       if (ret < 0)
       {
           LOG(FATAL, "send message error, error code : %d, error string : %s", errno, strerror(errno));
           exit(SEND_ERROR);
       }

       char buff[1024];
       // 接收数据
       int m = ::recv(sockfd, buff, sizeof(buff) - 1, 0);
       if (m > 0)
       {
           buff[m] = 0;
           std::cout << "Server Echo$ " << buff << std::endl;
       }
   }
}

• TcpServer.hpp文件

#pragma once

#include <sys/types.h> /* See NOTES */
#include <sys/wait.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include <error.h>
#include <string.h>
#include <pthread.h>
#include <functional>

#include "Log.hpp"
#include "InetAddr.hpp"
#include "Comm.hpp"


const int defaultsockfd = -1;
int gbacklog = 16; // 暂时先用

using callback_t = std::function<std::string(std::string)>;

// 声明
class TcpServer;

class ThreadData
{
public:
   ThreadData(int sockfd, InetAddr addr, TcpServer *self)
       : _sockfd(sockfd), _addr(addr), _self(self) {}
   ~ThreadData() = default;

public:
   int _sockfd;
   InetAddr _addr;
   TcpServer *_self;
};

class TcpServer
{
public:
   TcpServer(uint16_t port, callback_t cb) : _port(port), _listensock(defaultsockfd), _isrunning(false), _cb(cb)
   {
   }

   void InitServer()
   {
       // 创建
       _listensock = socket(AF_INET, SOCK_STREAM, 0); // 这个就是文件描述符
       if (_listensock < 0)
       {
           LOG(FATAL, "create sockfd error, error code : %d, error string : %s", errno, strerror(errno));
           exit(CREATE_ERROR);
       }
       LOG(INFO, "create sockfd success");

       struct sockaddr_in local;
       bzero(&local, sizeof(local));
       local.sin_family = AF_INET;
       local.sin_port = htons(_port);
       local.sin_addr.s_addr = INADDR_ANY;
       // 绑定
       int n = ::bind(_listensock, CONV(&local), sizeof(local));
       if (n < 0)
       {
           LOG(FATAL, "bind sockfd error, error code : %d, error string : %s", errno, strerror(errno));
           exit(BIND_ERROR);
       }
       LOG(INFO, "bind sockfd success");
   }

   void Service(int sockfd, InetAddr client)
   {
       while (true)
       {
           // TCP是字节流（可以使用write和read接口），UDP是数据报
           char buff[1024];
           // 接收消息
           int n = ::read(sockfd, buff, sizeof(buff)); // bug，接收数据可能收到的不完整，比如1+100，可能先收到1+1，再收到00 -- 按序到达
           std::string clientAddr = CombineIpAndPort(client);

           if (n > 0)
           {
               buff[n] = 0;
               std::string message = clientAddr + buff;
               LOG(INFO, "get message : \n %s", message.c_str());

               // 发送消息
               std::string response = _cb(buff); // 回调
               int m = ::write(sockfd, response.c_str(), response.size());
               if (m < 0)
               {
                   LOG(FATAL, "send message error ,error code : %d , error string : %s", errno, strerror(errno));
                   exit(SEND_ERROR);
               }
           }
           else if (n == 0)
           {
               // 发送端不发送数据了
               LOG(INFO, "%s quit", clientAddr.c_str());
               break;
           }
           else
           {
               LOG(FATAL, "recv message error ,error code : %d , error string : %s", errno, strerror(errno));
               exit(RECV_ERROR);
           }
       }
       ::close(sockfd); // 服务结束，关闭文件描述符，避免文件描述符泄漏
   }

   static void *HandlerService(void *args)
   {
       pthread_detach(pthread_self()); // 分离线程
       ThreadData *td = static_cast<ThreadData *>(args);
       td->_self->Service(td->_sockfd, td->_addr);
       delete td;
       return nullptr;
   }

   void Start()
   {
       _isrunning = true;
       while (_isrunning)
       {
           // 监听
           int ret = ::listen(_listensock, gbacklog);
           if (ret < 0)
           {
               LOG(FATAL, "listen error, error code : %d , error string : %s", errno, strerror(errno));
               exit(LISTEN_ERROR);
           }
           LOG(INFO, "listen success!");

           struct sockaddr_in peer;
           socklen_t len = sizeof(peer);
           // 获取新连接
           int sockfd = accept(_listensock, CONV(&peer), &len); // 建立连接成功，创建新文件描述符进行通信
           if (sockfd < 0)
           {
               LOG(WARNING, "accept error, error code : %d , error string : %s", errno, strerror(errno));
               continue;
           }
           LOG(INFO, "accept success! new sockfd : %d", sockfd);

           InetAddr addr(peer); // 给后面提供传入的ip、port
           // 服务 -- 发送和接收数据

           // v2 -- 多线程
           pthread_t tid;
           ThreadData *td = new ThreadData(sockfd, addr, this); // 传指针
           pthread_create(&tid, nullptr, HandlerService, td);   // 这里创建线程后，线程去做执行任务，主线程继续向下执行 , 并且线程不能关闭sockf，线程和进程共享文件描述符表
       }
       _isrunning = false;
   }

   ~TcpServer()
   {
       if (_listensock > defaultsockfd)
           ::close(_listensock); // 不用了关闭监听
   }

private:
   uint16_t _port;
   int _listensock;
   bool _isrunning;

   callback_t _cb;
};

• 运行结果：

4、TCP客户端connect断线重连

这里是服务器响应程序的断线重连的实现细节：TCP客户端connect断线重连

5、应用层自定义协议以及序列化和反序列化

这里是应用层自定义协议以及序列化和反序列化的实现细节：应用层自定义协议以及序列化和反序列化

里面还包含复杂的TCP网络程序：服务器网络计算器

OKOK，Linux网络编程之TCP就到这里，如果你对Linux和C++也感兴趣的话，可以看看我的主页哦。下面是我的github主页，里面记录了我的学习代码和leetcode的一些题的题解，有兴趣的可以看看。

Xpccccc的github主页