小编luk*_*ash的帖子

考虑这段代码：

#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

#define SERVADDR "::1"
#define PORT 12345

int main() {
    int sd = -1;

    if ((sd = socket(AF_INET6, SOCK_STREAM, 0)) < 0) {
        fprintf(stderr, "socket() failed: %d", errno);
        exit(1);
    }

    int flag = 1;
    if(setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag)) == -1) {
        fprintf(stderr, "Setsockopt %d, SO_REUSEADDR failed with errno %d\n", sd, errno);
        exit(2);
    }
    if(setsockopt(sd, SOL_SOCKET, SO_REUSEPORT, &flag, sizeof(flag)) == -1) {
        fprintf(stderr, "Setsockopt …