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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <errno.h>
#define PORT 8080
#define MAX_EVENTS 64
#define BUFFER_SIZE 1024
void set_nonblocking(int32_t fd)
{
int32_t flags = fcntl(fd, F_GETFL, 0);
fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}
int32_t main(void)
{
int32_t server_fd = socket(AF_INET, SOCK_STREAM, 0);
int32_t opt = 1;
setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
struct sockaddr_in address = {
.sin_family = AF_INET,
.sin_addr.s_addr = INADDR_ANY,
.sin_port = htons(PORT)
};
bind(server_fd, (struct sockaddr *)&address, sizeof(address));
listen(server_fd, SOMAXCONN);
set_nonblocking(server_fd);
printf("server listening on port %d...\n", PORT);
int32_t epoll_fd = epoll_create1(0);
if (epoll_fd < 0) {
perror("epoll_create1 failed");
exit(EXIT_FAILURE);
}
struct epoll_event ev;
ev.events = EPOLLIN;
ev.data.fd = server_fd;
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, server_fd, &ev) < 0) {
perror("epoll_ctl: server_fd failed");
exit(EXIT_FAILURE);
}
struct epoll_event events[MAX_EVENTS];
char buffer[BUFFER_SIZE];
while (1) {
int32_t nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
if (nfds < 0) {
perror("epoll_wait failed");
break;
}
for (int32_t i = 0; i < nfds; i++) {
if (events[i].data.fd == server_fd) {
struct sockaddr_in client_addr;
socklen_t client_len = sizeof(client_addr);
int32_t client_fd = accept(server_fd, (struct sockaddr *)&client_addr, &client_len);
if (client_fd < 0) {
perror("accept failed");
continue;
}
printf("connection accepted (client fd: %d)\n", client_fd);
set_nonblocking(client_fd);
ev.events = EPOLLIN | EPOLLET;
ev.data.fd = client_fd;
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client_fd, &ev) < 0) {
perror("epoll_ctl: client_fd failed");
close(client_fd);
}
} else {
int32_t client_fd = events[i].data.fd;
while (1) {
ssize_t bytes_read = read(client_fd, buffer, sizeof(buffer));
if (bytes_read > 0) {
write(client_fd, buffer, bytes_read);
} else if (bytes_read == 0) {
printf("client on fd %d closed connection.\n", client_fd);
epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client_fd, NULL);
close(client_fd);
break;
} else {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
break;
}
perror("read error");
epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client_fd, NULL);
close(client_fd);
break;
}
}
}
}
}
close(epoll_fd);
close(server_fd);
return 0;
}
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