refer:hostloc
Author:dunce

#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>

const char* redir = "HTTP/1.1 301 Moved Permanently\r\n"
        "Location: http://www.baidu.com\r\n\r\n";

int main()
{
        struct sockaddr_in sa;
        memset(&sa,0,sizeof(sa));
        sa.sin_family = AF_INET;
        sa.sin_port = htons(8888);
        
        int fd = socket(AF_INET,SOCK_STREAM,0);
        bind(fd,(struct sockaddr*)&sa,sizeof(sa));
        listen(fd,16);

        int xfd;
        while(1)
        {
                xfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK);
                write(xfd, redir, strlen(redir));
                close(xfd);
        }
        close(fd);
}