【在Linux世界中追寻伟大的One Piece】Socket编程UDP

目录

1 -> UDP网络编程

1.1 -> V1版本 -echo server

1.2 -> V2版本 -DictServer

1.3 -> V2版本 -DictServer(封装版)

---

1 -> UDP网络编程

1.1 -> V1版本 -echo server

简单的回显服务器和客户端代码。

备注：代码中会用到地址转换函数。

nocopy.hpp

#pragma once
#include <iostream>class nocopy
{
public:nocopy() {}nocopy(const nocopy&) = delete;const nocopy& operator = (const nocopy&) = delete;~nocopy() {}
};

UdpServer.hpp

#pragma once
#include <iostream>
#include <string>
#include <cerrno>
#include <cstring>
#include <unistd.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "nocopy.hpp"
#include "Log.hpp"
#include "Comm.hpp"
#include "InetAddr.hpp"const static uint16_t defaultport = 8888;
const static int defaultfd = -1;
const static int defaultsize = 1024;class UdpServer : public nocopy
{
public:UdpServer(uint16_t port = defaultport): _port(port), _sockfd(defaultfd){}void Init(){// 1. 创建 socket，就是创建了文件细节_sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (_sockfd < 0){lg.LogMessage(Fatal, "socket errr, %d : %s\n", errno,strerror(errno));exit(Socket_Err);}lg.LogMessage(Info, "socket success, sockfd: %d\n",_sockfd);// 2. 绑定，指定网络信息struct sockaddr_in local;bzero(&local, sizeof(local)); // memsetlocal.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY; // 0// local.sin_addr.s_addr = inet_addr(_ip.c_str()); // 1. 4字节 IP 2. 变成网络序列// 结构体填完，设置到内核中了吗？？没有int n = ::bind(_sockfd, (struct sockaddr*)&local,sizeof(local));if (n != 0){lg.LogMessage(Fatal, "bind errr, %d : %s\n", errno,strerror(errno));exit(Bind_Err);}}void Start(){// 服务器永远不退出char buffer[defaultsize];for (;;){struct sockaddr_in peer;socklen_t len = sizeof(peer); // 不能乱写ssize_t n = recvfrom(_sockfd, buffer, sizeof(buffer) -1, 0, (struct sockaddr*)&peer, &len);if (n > 0){InetAddr addr(peer);buffer[n] = 0;std::cout << "[" << addr.PrintDebug() << "]# " <<buffer << std::endl;sendto(_sockfd, buffer, strlen(buffer), 0, (structsockaddr*)&peer, len);}}}~UdpServer(){}private:// std::string _ip; // 后面要调整uint16_t _port;int _sockfd;
};

InetAddr.hpp

#pragma once
#include <iostream>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>class InetAddr
{
public:InetAddr(struct sockaddr_in& addr) :_addr(addr){_port = ntohs(_addr.sin_port);_ip = inet_ntoa(_addr.sin_addr);}std::string Ip() { return _ip; }uint16_t Port() { return _port; };std::string PrintDebug(){std::string info = _ip;info += ":";info += std::to_string(_port); // "127.0.0.1:4444"return info;}~InetAddr() {}private:std::string _ip;uint16_t _port;struct sockaddr_in _addr;
};

Comm.hpp

#pragma onceenum 
{Usage_Err = 1,Socket_Err,Bind_Err
};

• 云服务器不允许直接bind公有IP，我们也不推荐编写服务器的时候，bind明确的IP，推荐直接写成INADDR_ANY。

/* Address to accept any incoming messages. */#define INADDR_ANY ((in_addr_t) 0x00000000)

在网络编程中，当一个进程需要绑定一个网络端口以进行通信时，可以使用INADDR_ANY作为IP地址参数。这样做意味着该端口可以接受来自任何IP地址的连接请求，无论是本地主机还是远程主机。例如，如果服务器有多个网卡(每个网卡上有不同的IP地址)，使用INADDR_ANY可以省去确定数据是从服务器上具体哪个网卡/IP地址上面获取的。

UdpClient.hpp

#include <iostream>
#include <cerrno>
#include <cstring>
#include <string>
#include <unistd.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>void Usage(const std::string& process)
{std::cout << "Usage: " << process << " server_ip server_port"<< std::endl;
}// ./udp_client server_ip server_port
int main(int argc, char* argv[])
{if (argc != 3){Usage(argv[0]);return 1;}std::string serverip = argv[1];uint16_t serverport = std::stoi(argv[2]);// 1. 创建 socketint sock = socket(AF_INET, SOCK_DGRAM, 0);if (sock < 0){std::cerr << "socket error: " << strerror(errno) <<std::endl;return 2;}std::cout << "create socket success: " << sock << std::endl;// 2. client 要不要进行 bind? 一定要 bind 的！！// 但是，不需要显示 bind，client 会在首次发送数据的时候会自动进行bind// 为什么？server 端的端口号，一定是众所周知，不可改变的，client 需要 port，bind 随机端口.// 为什么？client 会非常多.// client 需要 bind，但是不需要显示 bind，让本地 OS 自动随机 bind，选择随机端口号// 2.1 填充一下 server 信息struct sockaddr_in server;memset(&server, 0, sizeof(server));server.sin_family = AF_INET;server.sin_port = htons(serverport);server.sin_addr.s_addr = inet_addr(serverip.c_str());while (true){// 我们要发的数据std::string inbuffer;std::cout << "Please Enter# ";std::getline(std::cin, inbuffer);// 我们要发给谁呀？serverssize_t n = sendto(sock, inbuffer.c_str(),inbuffer.size(), 0, (struct sockaddr*)&server, sizeof(server));if (n > 0){char buffer[1024];//收消息struct sockaddr_in temp;socklen_t len = sizeof(temp);ssize_t m = recvfrom(sock, buffer, sizeof(buffer) - 1,0, (struct sockaddr*)&temp, &len); // 一般建议都是要填的.if (m > 0){buffer[m] = 0;std::cout << "server echo# " << buffer <<std::endl;}elsebreak;}elsebreak;}close(sock);return 0;
}

1.2 -> V2版本 -DictServer

实现一个简单的英译汉的网络字典

dict.txt

apple：苹果

banana：香蕉

cat：猫

dog：狗

book：书

pen：笔

happy：快乐的

sad：悲伤的

run：跑

jump：跳

teacher：老师

student：学生

car：汽车

bus：公交车

love：爱

hate：恨

hello：你好

goodbye：再见

summer：夏天

winter：冬天

Dict.hpp

#pragma once
#include <iostream>
#include <string>
#include <fstream>
#include <unordered_map>const std::string sep = ": ";class Dict
{
private:void LoadDict(){std::ifstream in(_confpath);if (!in.is_open()){std::cerr << "open file error" << std::endl; // 后面可以用日志替代打印return;}std::string line;while (std::getline(in, line)){if (line.empty()) continue;auto pos = line.find(sep);if (pos == std::string::npos) continue;std::string key = line.substr(0, pos);std::string value = line.substr(pos + sep.size());_dict.insert(std::make_pair(key, value));}in.close();}public:Dict(const std::string& confpath) :_confpath(confpath){LoadDict();}std::string Translate(const std::string& key){auto iter = _dict.find(key);if (iter == _dict.end()) return std::string("Unknown");else return iter->second;}~Dict(){}private:std::string _confpath;std::unordered_map<std::string, std::string> _dict;
};

UdpServer.hpp

#pragma once
#include <iostream>
#include <string>
#include <cerrno>
#include <cstring>
#include <unistd.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unordered_map>
#include <functional>
#include "nocopy.hpp"
#include "Log.hpp"
#include "Comm.hpp"
#include "InetAddr.hpp"const static uint16_t defaultport = 8888;
const static int defaultfd = -1;
const static int defaultsize = 1024;using func_t = std::function<void(const std::string& req,std::string* resp)>;class UdpServer : public nocopy
{
public:UdpServer(func_t func, uint16_t port = defaultport): _func(func), _port(port), _sockfd(defaultfd){}void Init(){// 1. 创建 socket，就是创建了文件细节_sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (_sockfd < 0){lg.LogMessage(Fatal, "socket errr, %d : %s\n", errno,strerror(errno));exit(Socket_Err);}lg.LogMessage(Info, "socket success, sockfd: %d\n",_sockfd);// 2. 绑定，指定网络信息struct sockaddr_in local;bzero(&local, sizeof(local)); // memsetlocal.sin_family = AF_INET;local.sin_port = htons(_port);local.sin_addr.s_addr = INADDR_ANY; // 0// local.sin_addr.s_addr = inet_addr(_ip.c_str()); // 1. 4字节 IP 2. 变成网络序列// 结构体填完，设置到内核中了吗？？没有int n = ::bind(_sockfd, (struct sockaddr*)&local,sizeof(local));if (n != 0){lg.LogMessage(Fatal, "bind errr, %d : %s\n", errno,strerror(errno));exit(Bind_Err);}}void Start(){// 服务器永远不退出char buffer[defaultsize];for (;;){struct sockaddr_in peer;socklen_t len = sizeof(peer); // 不能乱写ssize_t n = recvfrom(_sockfd, buffer, sizeof(buffer) -1, 0, (struct sockaddr*)&peer, &len);if (n > 0){InetAddr addr(peer);buffer[n] = 0;std::cout << "[" << addr.PrintDebug() << "]# " <<buffer << std::endl;std::string value;_func(buffer, &value); // 回调业务翻译方法sendto(_sockfd, value.c_str(), value.size(), 0,(struct sockaddr*)&peer, len);}}}~UdpServer(){}private:// std::string _ip; // 后面要调整uint16_t _port;int _sockfd;func_t _func;
};

Main.cc

#include "UdpServer.hpp"
#include "Comm.hpp"
#include "Dict.hpp"
#include <memory>void Usage(std::string proc)
{std::cout << "Usage : \n\t" << proc << " local_port\n" <<std::endl;
}Dict gdict("./dict.txt");
void Execute(const std::string& req, std::string* resp)
{*resp = gdict.Translate(req);
}// ./udp_server 8888
int main(int argc, char* argv[])
{if (argc != 2){Usage(argv[0]);return Usage_Err;}// std::string ip = argv[1];uint16_t port = std::stoi(argv[1]);std::unique_ptr<UdpServer> usvr =std::make_unique<UdpServer>(Execute, port);usvr->Init();usvr->Start();return 0;
}

1.3 -> V2版本 -DictServer(封装版)

udp_socket.hpp

#pragma once
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <cassert>
#include <string>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>typedef struct sockaddr sockaddr;
typedef struct sockaddr_in sockaddr_in;class UdpSocket 
{
public:UdpSocket() : fd_(-1) {}bool Socket() {fd_ = socket(AF_INET, SOCK_DGRAM, 0);if (fd_ < 0) {perror("socket");return false;}return true;}bool Close() {close(fd_);return true;}bool Bind(const std::string& ip, uint16_t port) {sockaddr_in addr;addr.sin_family = AF_INET;addr.sin_addr.s_addr = inet_addr(ip.c_str());addr.sin_port = htons(port);int ret = bind(fd_, (sockaddr*)&addr, sizeof(addr));if (ret < 0) {perror("bind");return false;}return true;}bool RecvFrom(std::string* buf, std::string* ip = NULL,uint16_t* port = NULL) {char tmp[1024 * 10] = { 0 };sockaddr_in peer;socklen_t len = sizeof(peer);ssize_t read_size = recvfrom(fd_, tmp,sizeof(tmp) - 1, 0,(sockaddr*)&peer, &len);if (read_size < 0) {perror("recvfrom");return false;}// 将读到的缓冲区内容放到输出参数中buf->assign(tmp, read_size);if (ip != NULL) {*ip = inet_ntoa(peer.sin_addr);}if (port != NULL) {*port = ntohs(peer.sin_port);}return true;}bool SendTo(const std::string& buf, const std::string& ip,uint16_t port) {sockaddr_in addr;addr.sin_family = AF_INET;addr.sin_addr.s_addr = inet_addr(ip.c_str());addr.sin_port = htons(port);ssize_t write_size = sendto(fd_, buf.data(), buf.size(), 0,(sockaddr*)&addr, sizeof(addr));if (write_size < 0) {perror("sendto");return false;}return true;}private:int fd_;
};

UDP通用服务器

udp_server.hpp

#pragma once
#include "udp_socket.hpp"// C 式写法
// typedef void (*Handler)(const std::string& req, std::string*resp);
// C++ 11 式写法, 能够兼容函数指针, 仿函数, 和 lambda#include <functional>typedef std::function<void(const std::string&, std::string*resp)> Handler;class UdpServer 
{
public:UdpServer() {assert(sock_.Socket());}~UdpServer() {sock_.Close();}bool Start(const std::string& ip, uint16_t port, Handlerhandler) {// 1. 创建 socket// 2. 绑定端口号bool ret = sock_.Bind(ip, port);if (!ret) {return false;}// 3. 进入事件循环for (;;) {// 4. 尝试读取请求std::string req;std::string remote_ip;uint16_t remote_port = 0;bool ret = sock_.RecvFrom(&req, &remote_ip, &remote_port);if (!ret) {continue;}std::string resp;// 5. 根据请求计算响应handler(req, &resp);// 6. 返回响应给客户端sock_.SendTo(resp, remote_ip, remote_port);printf("[%s:%d] req: %s, resp: %s\n", remote_ip.c_str(),remote_port,req.c_str(), resp.c_str());}sock_.Close();return true;}private:UdpSocket sock_;
};

实现英译汉服务器

以上代码是对udp服务器进行通用接口的封装。基于以上封装，实现一个查字典的服务器就很容易了。

dict_server.cc

#include "udp_server.hpp"
#include <unordered_map>
#include <iostream>std::unordered_map<std::string, std::string> g_dict;void Translate(const std::string& req, std::string* resp) 
{auto it = g_dict.find(req);if (it == g_dict.end()) {*resp = "未查到!";return;}*resp = it->second;
}int main(int argc, char* argv[]) 
{if (argc != 3) {printf("Usage ./dict_server [ip] [port]\n");return 1;}// 1. 数据初始化g_dict.insert(std::make_pair("hello", "你好"));g_dict.insert(std::make_pair("world", "世界"));g_dict.insert(std::make_pair("c++", "最好的编程语言"));g_dict.insert(std::make_pair("bit", "特别 NB"));// 2. 启动服务器UdpServer server;server.Start(argv[1], atoi(argv[2]), Translate);return 0;
}

UDP通用客户端

udp_client.hpp

#pragma once
#include "udp_socket.hpp"class UdpClient 
{
public:UdpClient(const std::string& ip, uint16_t port) : ip_(ip),port_(port) {assert(sock_.Socket());}~UdpClient() {sock_.Close();}bool RecvFrom(std::string* buf) {return sock_.RecvFrom(buf);}bool SendTo(const std::string& buf) {return sock_.SendTo(buf, ip_, port_);}private:UdpSocket sock_;// 服务器端的 IP 和 端口号std::string ip_;uint16_t port_;
};

实现英译汉客户端

#include "udp_client.hpp"
#include <iostream>int main(int argc, char* argv[]) 
{if (argc != 3) {printf("Usage ./dict_client [ip] [port]\n");return 1;}UdpClient client(argv[1], atoi(argv[2]));for (;;) {std::string word;std::cout << "请输入您要查的单词: ";std::cin >> word;if (!std::cin) {std::cout << "Good Bye" << std::endl;break;}client.SendTo(word);std::string result;client.RecvFrom(&result);std::cout << word << " 意思是 " << result << std::endl;}return 0;
}

---

感谢各位大佬支持！！！

互三啦！！！