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 1024
using 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;
}