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I/O复用的高级应用:同时处理 TCP 和 UDP 服务
2022-04-23 14:36:00 【m0_51551385】
1、I/O复用的另一用武之地:同时处理 TCP 和 UDP 服务
同一端口(或socket地址)既能接收UDP请求也能接收TCP请求。我们使用同一个socket地址创建两个 socket 文件描述符,分别用于处理该端口上的UDP和TCP请求。然后使用I/O复用技术同时监听这两个socket 文件描述符的事件,就可以实现同时处理一个端口上的 TCP 和 UDP 请求。
2、实例程序
下面是一个服务器程序,他能同时处理 TCP 和 UDP 服务。
/* 本程序实现一个同时处理 TCP 请求和 UDP 请求的回射服务器 */
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<assert.h>
#include<unistd.h>
#include<stdio.h>
#include<fcntl.h>
#include<stdlib.h>
#include<string.h>
#include<sys/epoll.h>
#include<pthread.h>
#include<errno.h>
#define MAX_EVENT_NUMBER 1024
#define TCP_BUFFER_SIZE 512
#define UDP_BUFFER_SIZE 1024
int setnonblocking(int fd)
{
int old_option = fcntl(fd, F_GETFL);
int new_option = old_option | O_NONBLOCK;
fcntl(fd, F_SETFL, new_option);
return new_option;
}
void addfd(int epollfd, int fd)
{
epoll_event event;
event.data.fd = fd;
event.events = EPOLLIN | EPOLLET;
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
setnonblocking(fd);
}
int main(int argc, char* argv[])
{
if (argc <= 2)
{
return 1;
}
const char* ip = argv[1];
int port = atoi(argv[2]);
struct sockaddr_in address;
bzero(&address, sizeof(address));
address.sin_port = htons(port);
address.sin_family = AF_INET;
inet_pton(AF_INET, ip, &address.sin_addr);
/* 创建 TCP socket,并将其绑定到端口 port 上 */
int listenfd = socket(PF_INET, SOCK_STREAM, 0);
assert(listenfd >= 0);
int ret = bind(listenfd, (struct sockaddr*)&address, sizeof(address));
assert(ret != -1);
ret = listen(listenfd, 5);
assert(ret != -1);
/* 创建 UDP socket,并将其绑定到端口 port 上 */
bzero(&address, sizeof(address));
address.sin_family = AF_INET;
address.sin_port = htons(port);
inet_pton(AF_INET, ip, &address.sin_addr);
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(10);
assert(epollfd != -1);
/* 注册 TCP socket 和 UDP socket 上的可读事件 */
addfd(epollfd, listenfd);
addfd(epollfd, udpfd);
while (1)
{
int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
if (number < 0)
{
printf("epoll failure\n");
break;
}
for (int i = 0; i < number; i++)
{
int sockfd = events[i].data.fd;
if (sockfd == listenfd) /* 如果是 TCP 的监听 socket */
{
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) /* 如果是 UDP 的 socket */
{
char buf[UDP_BUFFER_SIZE];
memset(buf, '\0', UDP_BUFFER_SIZE);
struct sockaddr_in client_address;
socklen_t client_addrlength = sizeof(client_address);
ret = recvfrom(udpfd, buf, UDP_BUFFER_SIZE, 0, (struct sockaddr*)&client_address, &client_addrlength);
if (ret > 0)
{
sendto(udpfd, buf, UDP_BUFFER_SIZE - 1, 0, (struct sockaddr*)&client_address, client_addrlength);
}
}
else if (events[i].events & EPOLLIN) /* 如果是 TCP 可写事件 */
{
char buf[TCP_BUFFER_SIZE];
while (1) /* 由于 TCP 传输的是字节流,所以需要用 while 确保所有数据都被读出,UDP就不用使用 while */
{
memset(buf, '\0', TCP_BUFFER_SIZE);
ret = recv(events[i].data.fd, buf, TCP_BUFFER_SIZE - 1, 0);
if (ret < 0)
{
if (errno == EAGAIN || errno == EWOULDBLOCK) /* 在Vxorks和Windows上,EAGAIN 叫做 EWOULDBLOCK */
{
break;
}
close(sockfd);
break;
}
else if (ret == 0)
{
close(sockfd);
}
else
{
send(sockfd, buf, ret, 0);
}
}
}
else
{
printf("something else happened\n");
}
}
}
close(listenfd);
return 0;
}
版权声明
本文为[m0_51551385]所创,转载请带上原文链接,感谢
https://blog.csdn.net/m0_51551385/article/details/124363330
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