文章目录
- 前言
- 一. 服务器
- 1. 初始化服务器
- 2. 启动服务器
- 二. 客户端
- 三. 多进程服务器
- 结束语
前言
本系列文章是计算机网络学习的笔记，欢迎大佬们阅读，纠错，分享相关知识。希望可以与你共同进步。
本篇博客基于UDP socket基础，介绍TCP socket编程接口和细节
UDP socket编程可参看【计算机网络学习之路】UDP socket编程
本次编写的服务器和客户端依然是最简单的echo服务器
一. 服务器
服务器的基本框架：
tcp_server.hpp
#pragma once#include <iostream>
#include <string>
#include <cstring>
#include <cerrno>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>namespace ns_server
{const uint16_t default_port = 8888;class TcpServer{public:TcpServer(uint16_t port = default_port) : _port(port){}void InitServer(){}//初始化服务器void Start(){}//启动服务器~TcpServer(){}private:int _sock; // 监听套接字uint16_t _port; // 端口号};
}
tcp_server.cc
#include"tcp_server.hpp"
#include<memory>using namespace std;
using namespace ns_server;static void usage(char*argv)
{cout<<"Usage\n\t"<<argv<<" serverPort"<<endl;
}
int main(int argc,char*argv[])
{if(argc!=2){usage(argv[0]);exit(USAGE_ERR);}uint16_t port=atoi(argv[1]);unique_ptr<TcpServer> usvr(new TcpServer(echo,port));usvr->InitServer();usvr->Start();return 0;
}
1. 初始化服务器
服务器的初始化，还是一样的
- 创建套接字
- 绑定套接字
void InitServer()
{// 1.创建套接字_sock = socket(AF_INET, SOCK_STREAM, 0);if (_listensock < 0){std::cerr << "create sock error," << strerror(errno) << std::endl;exit(1);}std::cout << "create listensock success: " << _sock << std::endl;// 2.绑定套接字struct sockaddr_in local;local.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY;if (bind(_sock , (struct sockaddr *)&local, sizeof(local)) < 0){std::cerr << "bind error," << strerror(errno) << std::endl;exit(2);}
}
需要注意的是，socket的第二个参数为SOCK_STREAM面向字节流
TCP与UDP不同的地方是，TCP是面向连接的，UDP是无连接的
所以TCP还需要listen
返回值：成功返回0，失败返回-1并设置错误码
backlog参数需要在后续TCP详解中学习，先定义大小为32
const int backlog = 32;
void InitServer()
{// 1.创建套接字_sock = socket(AF_INET, SOCK_STREAM, 0);if (_listensock < 0){std::cerr << "create sock error," << strerror(errno) << std::endl;exit(1);}std::cout << "create listensock success: " << _sock << std::endl;// 2.绑定套接字struct sockaddr_in local;local.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY;if (bind(_sock , (struct sockaddr *)&local, sizeof(local)) < 0){std::cerr << "bind error," << strerror(errno) << std::endl;exit(2);}// 3.监听if (listen(_listensock, backlog) < 0){std::cerr << "listen error," << strerror(errno) << std::endl;exit(3);}
}
初始化到此就结束了
接下来是启动服务器
2. 启动服务器
TCP通过accept获取客户端连接
sockfd：socket返回的文件描述符addr：输入输出型参数，客户端信息的结构体addrlen：输入输出型参数，结构体大小。注意：需要传入addr的大小返回值是网络文件描述符
在TCP中，socket返回的网络文件可以理解为连接文件，内部保存了连接信息
而accept是从连接文件中获取连接，然后创建套接字，网络文件。
真正通信的是connect创建的网络文件
我们将私有成员的_sock改为_listensock
void Start()
{while (true){struct sockaddr_in client;memset(&client, 0, sizeof(client));socklen_t len = sizeof(client);int sock = accept(_listensock, (struct sockaddr *)&client, &len);if (sock < 0){std::cerr << "accept error" << std::endl;continue;}// 提取客户端信息std::string clientIp = inet_ntoa(client.sin_addr);uint16_t clientPort = ntohs(client.sin_port);std::string name = "[" + clientIp + ":" + std::to_string(clientPort) + "]";std::cout << "create sock " << sock << " from " << _listensock << std::endl;}
}
接下来就可以在connect返回的套接字中读写数据了。
本次使用read和write
void Start()
{while (true){struct sockaddr_in client;memset(&client, 0, sizeof(client));socklen_t len = sizeof(client);int sock = accept(_listensock, (struct sockaddr *)&client, &len);if (sock < 0){std::cerr << "accept error" << std::endl;continue;}// 提取客户端信息std::string clientIp = inet_ntoa(client.sin_addr);uint16_t clientPort = ntohs(client.sin_port);std::string name = "[" + clientIp + ":" + std::to_string(clientPort) + "]";std::cout << "create sock " << sock << " from " << _listensock << std::endl;char buffer[1024];while (true){int n = read(sock, buffer, sizeof(buffer) - 1);if (n > 0){buffer[n] = '\0';std::cout << name << "# " << buffer << std::endl;std::string responce = buffer;//返回收到的数据int m = write(sock, responce.c_str(), responce.size());}else if (n == 0){// 写端关闭std::cout << name << " quit,me to" << std::endl;close(sock);break;}else{// 读数据异常std::cerr << "read error" << std::endl;break;}}}
}
完整代码：
tcp_server.hpp
#pragma once#include <iostream>
#include <string>
#include <cstring>
#include <cerrno>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>namespace ns_server
{const uint16_t default_port = 8888;const int backlog = 32;class TcpServer{public:TcpServer(func_t func, uint16_t port = default_port) : _port(port), _func(func){}void InitServer(){// 1.创建套接字_listensock = socket(AF_INET, SOCK_STREAM, 0);if (_listensock < 0){std::cerr << "create sock error," << strerror(errno) << std::endl;exit(1);}std::cout << "create listensock success: " << _listensock << std::endl;// 2.绑定套接字struct sockaddr_in local;local.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY;if (bind(_listensock, (struct sockaddr *)&local, sizeof(local)) < 0){std::cerr << "bind error," << strerror(errno) << std::endl;exit(2);}// 3.监听if (listen(_listensock, backlog) < 0){std::cerr << "listen error," << strerror(errno) << std::endl;exit(3);}}void Start(){while (true){struct sockaddr_in client;memset(&client, 0, sizeof(client));socklen_t len = sizeof(client);int sock = accept(_listensock, (struct sockaddr *)&client, &len);if (sock < 0){std::cerr << "accept error" << std::endl;continue;}// 提取客户端信息std::string clientIp = inet_ntoa(client.sin_addr);uint16_t clientPort = ntohs(client.sin_port);std::string name = "[" + clientIp + ":" + std::to_string(clientPort) + "]";std::cout << "create sock " << sock << " from " << _listensock << std::endl;char buffer[1024];while (true){int n = read(sock, buffer, sizeof(buffer) - 1);if (n > 0){buffer[n] = '\0';std::cout << name << "# " << buffer << std::endl;std::string responce = buffer;int m = write(sock, responce.c_str(), responce.size());}else if (n == 0){// 写端关闭std::cout << name << " quit,me to" << std::endl;close(sock);break;}else{// 读数据异常std::cerr << "read error" << std::endl;break;}}}}~TcpServer(){}private:int _listensock; // 监听套接字uint16_t _port; // 端口号};
}
PS：上述的服务器是单进程，所以只能同时处理一个客户端，读者可以尝试添加一下多进程，多线程或者线程池
本篇博客最后会贴出多进程的方案
二. 客户端
客户端就不作封装了
最开始也是要创建套接字
然后TCP的客户端需要connect服务器
sockfd：socket返回的文件描述符addr：服务器信息的结构体addrlen：结构体大小。返回值：成功返回0，失败返回-1并设置错误码
注意：connect时OS会bind客户端
UDP是在发送数据时才会bind
#include <iostream>
#include <string>
#include <unistd.h>
#include <cstring>
#include <cerrno>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>using namespace std;static void usage(char *argv)
{cout << "Usage:\n\t" << argv << " serverIp serverPort" << endl;
}int main(int argc, char *argv[])
{if (argc != 3){usage(argv[0]);exit(USAGE_ERR);}string serverIp = argv[1];uint16_t serverPort = atoi(argv[2]);// 1.创建套接字int sock = socket(AF_INET, SOCK_STREAM, 0);if (sock < 0){cerr << "create sock error," << strerror(errno) << endl;exit(SOCKET_ERR);}cout<<"create sock sucess:"<<sock<<endl;// 2. 连接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);int cnt = 5; // 记录重连次数// connect时会bindwhile (connect(sock, (struct sockaddr *)&server, sizeof(server)) < 0){cout << "正在重连...还有" << cnt-- << "次" << endl;if (cnt <= 0){ cerr<<"连接失败"<<endl;exit(CONNECT_ERR);}sleep(1);}// 连接成功string name = "["+serverIp + ":" + to_string(serverPort)+"]";cout << "connect " << name << " sucess" << endl;return 0;
}
然后也可以开始读写数据了
完整代码：
tcp_client.cc
#include <iostream>
#include <string>
#include <unistd.h>
#include <cstring>
#include <cerrno>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>using namespace std;static void usage(char *argv)
{cout << "Usage:\n\t" << argv << " serverIp serverPort" << endl;
}int main(int argc, char *argv[])
{if (argc != 3){usage(argv[0]);exit(USAGE_ERR);}string serverIp = argv[1];uint16_t serverPort = atoi(argv[2]);// 1.创建套接字int sock = socket(AF_INET, SOCK_STREAM, 0);if (sock < 0){cerr << "create sock error," << strerror(errno) << endl;exit(SOCKET_ERR);}cout<<"create sock sucess:"<<sock<<endl;// 2. 连接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);int cnt = 5; // 记录重连次数// connect时会bindwhile (connect(sock, (struct sockaddr *)&server, sizeof(server)) < 0){cout << "正在重连...还有" << cnt-- << "次" << endl;if (cnt <= 0){ cerr<<"连接失败"<<endl;exit(CONNECT_ERR);}sleep(1);}// 连接成功string name = "["+serverIp + ":" + to_string(serverPort)+"]";cout << "connect " << name << " sucess" << endl;// 发送消息while (true){cout << "please enter your message# ";string message;getline(cin, message);int n = write(sock, message.c_str(), message.size());if (n < 0){cerr << "write error," << strerror(errno) << endl;break;}else if (n == 0){cout << "读端关闭，停止写" << endl;break;}char buffer[1024];int m = read(sock, buffer, sizeof(buffer) - 1);if (m > 0){buffer[n] = '\0';cout<<name<<" echo "<<buffer<<endl;}else if (m == 0){// 写端关闭std::cout << name << " quit,me to" << std::endl;close(sock);break;}else{// 读数据异常std::cerr << "read error" << std::endl;break;}}return 0;
}
三. 多进程服务器
tcp_server.hpp
#pragma once#include <iostream>
#include <string>
#include <cstring>
#include <cerrno>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>namespace ns_server
{const uint16_t default_port = 8888;const int backlog = 32;class TcpServer{public:TcpServer(uint16_t port = default_port) : _port(port){}void InitServer(){// 1.创建套接字_listensock = socket(AF_INET, SOCK_STREAM, 0);if (_listensock < 0){std::cerr << "create sock error," << strerror(errno) << std::endl;exit(1);}std::cout << "create listensock success: " << _listensock << std::endl;// 2.绑定套接字struct sockaddr_in local;local.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY;if (bind(_listensock, (struct sockaddr *)&local, sizeof(local)) < 0){std::cerr << "bind error," << strerror(errno) << std::endl;exit(2);}// 3.监听if (listen(_listensock, backlog) < 0){std::cerr << "listen error," << strerror(errno) << std::endl;exit(3);}}void Start(){//忽略子进程的信号，不需要等待子进程退出（推荐！！！）signal(SIGCHLD,SIG_IGN);while (true){struct sockaddr_in client;memset(&client, 0, sizeof(client));socklen_t len = sizeof(client);int sock = accept(_listensock, (struct sockaddr *)&client, &len);if (sock < 0){std::cerr << "accept error" << std::endl;continue;}std::cout << "create sock " << sock << " from " << _listensock << std::endl;// 多进程pid_t id = fork();if (id < 0){close(sock);continue;}else if (id == 0){//子进程close(_listensock);//建议关掉不需要的fdif(fork()>0)exit(0);//子进程退掉，后续为孙子进程// 提取客户端信息std::string clientIp = inet_ntoa(client.sin_addr);uint16_t clientPort = ntohs(client.sin_port);service(sock, clientIp, clientPort);exit(0);}//父进程//一定关掉不需要的fd，防止fd泄露close(sock);//pid_t ret=waitpid(id,nullptr,0);//默认为阻塞等待//pid_t ret=waitpid(id,nullptr,WNOHANG);//非阻塞//if(ret==id) std::cout<<"wait "<<id<<" sucess"<<std::endl;}}void service(int sock, std::string &clientIp, uint16_t&clientPort){std::string name = "[" + clientIp + ":" + std::to_string(clientPort) + "]";char buffer[1024];while (true){int n = read(sock, buffer, sizeof(buffer) - 1);if (n > 0){buffer[n] = '\0';std::cout << name << "# " << buffer << std::endl;std::string responce = buffer;int m = write(sock, responce.c_str(), responce.size());}else if (n == 0){// 写端关闭std::cout << name << " quit,me to" << std::endl;close(sock);break;}else{// 读数据异常std::cerr << "read error" << std::endl;break;}}}~TcpServer(){}private:int _listensock; // 监听套接字uint16_t _port; // 端口号};
}
结束语
本篇博客到此结束，感谢看到此处。
欢迎大家纠错和补充
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