IO复用高级应用：同时处理TCP和UDP服务

一个socket只能与一个socket地址绑定即一个socket只能监听一个端口，服务器如果要同时监听多个端口就必须创建多个socket，若在同一个端口监听多个服务也要创建多个socket绑定到这个端口上。现在服务器监听一个端口上的TCP和UDP请求，并将发送来的数据回射到客户端。

服务端程序：

#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <stdio.h>#include <unistd.h>#include <errno.h>#include <string.h>#include <fcntl.h>#include <stdlib.h>#include <sys/epoll.h>#include <pthread.h>#define MAX_EVENT_NUMBER 1024 //最大事件数目#define TCP_BUFFER_SIZE 512//TCP缓冲区#define UDP_BUFFER_SIZE 1024//UDP缓冲区int setnonblocking( int fd )//设置为非阻塞描述符{    int old_option = fcntl( fd, F_GETFL );    int new_option = old_option | O_NONBLOCK;    fcntl( fd, F_SETFL, new_option );    return old_option;}void addfd( int epollfd, int fd )//注册事件{    epoll_event event;    event.data.fd = fd;    //event.events = EPOLLIN | EPOLLET;    event.events = EPOLLIN;//可读事件    epoll_ctl( epollfd, EPOLL_CTL_ADD, fd, &event );    setnonblocking( fd );}int main( int argc, char* argv[] ){    if( argc <= 2 )    {        printf( "usage: %s ip_address port_number\n", basename( argv[0] ) );        return 1;    }    const char* ip = argv[1];    int port = atoi( argv[2] );    int ret = 0;    struct sockaddr_in address;//绑定TCP端口    bzero( &address, sizeof( address ) );    address.sin_family = AF_INET;    inet_pton( AF_INET, ip, &address.sin_addr );    address.sin_port = htons( port );    int listenfd = socket( PF_INET, SOCK_STREAM, 0 );    assert( listenfd >= 0 );    ret = bind( listenfd, ( struct sockaddr* )&address, sizeof( address ) );    assert( ret != -1 );    ret = listen( listenfd, 5 );    assert( ret != -1 );    bzero( &address, sizeof( address ) );//绑定UDP端口    address.sin_family = AF_INET;    inet_pton( AF_INET, ip, &address.sin_addr );    address.sin_port = htons( port );    int udpfd = socket( PF_INET, SOCK_DGRAM, 0 );    assert( udpfd >= 0 );    ret = bind( udpfd, ( struct sockaddr* )&address, sizeof( address ) );    assert( ret != -1 );    epoll_event events[ MAX_EVENT_NUMBER ];    int epollfd = epoll_create( 5 );    assert( epollfd != -1 );    addfd( epollfd, listenfd );//TCP端口注册事件    addfd( epollfd, udpfd );//UDP端口注册事件    while( 1 )    {        int number = epoll_wait( epollfd, events, MAX_EVENT_NUMBER, -1 );//无限期等待事件发生        if ( number < 0 )        {            printf( "epoll failure\n" );            break;        }            for ( int i = 0; i < number; i++ )//EPOLL就绪事件        {            int sockfd = events[i].data.fd;            if ( sockfd == listenfd )//监听端口监听TCP连接事件            {                struct sockaddr_in client_address;                socklen_t client_addrlength = sizeof( client_address );                int connfd = accept( listenfd, ( struct sockaddr* )&client_address, &client_addrlength );                addfd( epollfd, connfd );            }            else if ( sockfd == udpfd )//UDP连接            {                char buf[ UDP_BUFFER_SIZE ];                memset( buf, '\0', UDP_BUFFER_SIZE );                struct sockaddr_in client_address;                socklen_t client_addrlength = sizeof( client_address );//客户端地址//UDP专用接收数据                ret = recvfrom( udpfd, buf, UDP_BUFFER_SIZE-1, 0, ( struct sockaddr* )&client_address, &client_addrlength );                if( ret > 0 )                {//UDP专用发送数据(回射数据)                    sendto( udpfd, buf, UDP_BUFFER_SIZE-1, 0, ( struct sockaddr* )&client_address, client_addrlength );                }            }            else if ( events[i].events & EPOLLIN )//TCP连接            {                char buf[ TCP_BUFFER_SIZE ];                while( 1 )                {                    memset( buf, '\0', TCP_BUFFER_SIZE );                    ret = recv( sockfd, buf, TCP_BUFFER_SIZE-1, 0 );                    if( ret < 0 )                    {                        if( ( errno == EAGAIN ) || ( errno == EWOULDBLOCK ) )//非阻塞出现这种errrno是读取数据完毕                        {                            break;                        }                        close( sockfd );                        break;                    }                    else if( ret == 0 )//关闭连接                    {                        close( sockfd );                    }                    else                    {                        send( sockfd, buf, ret, 0 );//回射数据                    }                }            }            else            {                printf( "something else happened \n" );            }        }    }    close( listenfd );    return 0;}

客户端程序：

#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<assert.h>#include<stdio.h>#include<unistd.h>#include<string.h>#include<stdlib.h>#include<iostream>#define BUF_SIZE 1024using namespace std;int main(int argc,char* argv[]){    if(argc<=2){        cout<<"argc<=2"<<endl;        return 1;    }    const char* ip=argv[1];    int port=atoi(argv[2]);    struct sockaddr_in server_address;    bzero(&server_address,sizeof(server_address));    server_address.sin_family=AF_INET;    inet_pton(AF_INET,ip,&server_address.sin_addr);    server_address.sin_port=htons(port);    int sockfd=socket(PF_INET,SOCK_STREAM,0);    int sockudp=socket(PF_INET,SOCK_DGRAM,0);    assert(sockfd>=0);    if(connect(sockfd,(struct sockaddr*)&server_address,sizeof(server_address))<0){//TCP数据发送与接收        cout<<"connect error"<<endl;        return 1;    }    else{        const char* tcp="this is TCP data\n";        send(sockfd,tcp,strlen(tcp),0);        char buf[BUF_SIZE];        int ret=recv(sockfd,buf,BUF_SIZE-1,0);        if(ret<0){            cout<<"recv tcp error"<<endl;        }        else{            buf[ret+1]='\0';            cout<<ret<<" "<<buf<<endl;        }    }    if(connect(sockudp,(struct sockaddr*)&server_address,sizeof(server_address))<0){//UDP数据发送与接收        cout<<"connect error"<<endl;        return 1;    }    else{        const char* udp="this is UDP data\n";        send(sockudp,udp,strlen(udp),0);        char buf[BUF_SIZE];        int ret=recv(sockudp,buf,BUF_SIZE-1,0);        if(ret<0){            cout<<"recv udp error"<<endl;        }        else{            buf[ret+1]='\0';            cout<<ret<<" "<<buf<<endl;        }    }    close(sockfd);    return 0;}