[英]UDP epoll detects the data only from single port
I was trying to implementing a program to understand the real working of UDP epoll.我试图实现一个程序来了解 UDP epoll 的实际工作。 I have done the code as below.
我已经完成了如下代码。 This is working for a single socket.
这适用于单个套接字。 But when I tried with multiple socket (say 4 sockets for 10000, 10001, 10002, 10003), it detects the data only on last socket (here 4th, ie 10003).
但是当我尝试使用多个套接字时(比如 4 sockets 代表 10000、10001、10002、10003),它只检测到最后一个套接字上的数据(这里是第 4 个,即 10003)。 Do any one look my code and let me know what is the issue here?
有人看我的代码,让我知道这里有什么问题吗?
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <sys/epoll.h>
#define MAX_EVENTS 20
#define MAXLINE 1024
int get_new_socket(int port)
{
int sockfd;
struct sockaddr_in servaddr;
if ((sockfd = socket(PF_INET, SOCK_DGRAM /*|SOCK_NONBLOCK|SOCK_CLOEXEC*/, IPPROTO_UDP)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = INADDR_ANY;
servaddr.sin_port = htons(port);
if (bind(sockfd, (const struct sockaddr *)&servaddr,
sizeof(servaddr)) < 0 )
{
perror("bind failed");
exit(EXIT_FAILURE);
}
return sockfd;
}
void recv_send_data(int sockfd)
{
char buffer[MAXLINE];
char *hello = "Hello from server";
struct sockaddr_in cliaddr;
int ret;
memset(&cliaddr, 0, sizeof(cliaddr));
int len = sizeof(cliaddr), n = 17;
n = recvfrom(sockfd, (char *)buffer, MAXLINE, 0, (struct sockaddr *)&cliaddr, &len);
perror("recvfrom");
buffer[n] = '\0';
printf("[%d]Client : %s\n", n, buffer);
ret = sendto(sockfd, (const char *)hello, 17, 0, (const struct sockaddr *)&cliaddr, len);
printf("sent back to client.[%d]\n", ret);
}
int main(int argc, char *argv[]) {
struct epoll_event ev, events[MAX_EVENTS];
int listen_sock, nfds, epollfd, n;
int start_port = 10000;
for(n = start_port; n < start_port + 4; n++) {
listen_sock = get_new_socket(n);
printf("Created socket[%d] for port %d\n", listen_sock, n);
epollfd = epoll_create1(0);
if (epollfd == -1) {
perror("epoll_create");
exit(EXIT_FAILURE);
}
ev.events = EPOLLIN;
ev.data.fd = listen_sock;
if (epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, &ev) == -1) {
perror("epoll_ctl: listen_sock");
exit(EXIT_FAILURE);
}
}
for (;;) {
printf("Waiting on epoll\n");
nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
if (nfds == -1) {
perror("epoll_pwait");
exit(EXIT_FAILURE);
}
printf("EPOLL wait over; processing...\n");
for (n = 0; n < nfds; ++n) {
if (events[n].data.fd == listen_sock) {
printf("Data received on: %d, listen_sock: %d\n", events[n].data.fd, listen_sock);
recv_send_data(listen_sock);
}
}
sleep(1);
}
}
Why are you creating epoll for each and every FD.为什么要为每个 FD 创建 epoll。 You need to create epoll only one using epoll_create and use for all fd.
您只需要使用 epoll_create 创建一个 epoll 并用于所有 fd。
epollfd = epoll_create1(0);
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