IPv6:connect()总是以errno 22失败

Question

操作系统是Ubuntu.我正在为基本的IPv6操作做一个简单的测试.PC通过集线器与IP摄像机(支持IPv6)连接.ping6测试成功.

$ ping6 -I eth1 fe80::240:8cff:fe94:451e
PING fe80::240:8cff:fe94:451e(fe80::240:8cff:fe94:451e) from fe80::224:8cff:fe90:ad3b eth1: 56 data bytes
64 bytes from fe80::240:8cff:fe94:451e: icmp_seq=1 ttl=64 time=3.86 ms
64 bytes from fe80::240:8cff:fe94:451e: icmp_seq=2 ttl=64 time=0.471 ms

代码如下:

#include <linux/in6.h>
#include <sys/socket.h>
#include <stdio.h>
#include <errno.h>

void main()
{
  int s, ret, err;
  struct sockaddr_in6 addr;

  s = socket(AF_INET6, SOCK_STREAM, 0);
  addr.sin6_family = AF_INET6;
  addr.sin6_port = htons(554);
  addr.sin6_flowinfo = 0;
  addr.sin6_scope_id = 0;
  addr.sin6_addr.s6_addr[0] = 0xfe;
  addr.sin6_addr.s6_addr[1] = 0x80;
  addr.sin6_addr.s6_addr[2] = 0x00;
  addr.sin6_addr.s6_addr[3] = 0x00;
  addr.sin6_addr.s6_addr[4] = 0x00;
  addr.sin6_addr.s6_addr[5] = 0x00;  
  addr.sin6_addr.s6_addr[6] = 0x00;
  addr.sin6_addr.s6_addr[7] = 0x00;
  addr.sin6_addr.s6_addr[8] = 0x02;
  addr.sin6_addr.s6_addr[9] = 0x40;
  addr.sin6_addr.s6_addr[10] = 0x8c;
  addr.sin6_addr.s6_addr[11] = 0xff;
  addr.sin6_addr.s6_addr[12] = 0xfe;
  addr.sin6_addr.s6_addr[13] = 0x94;
  addr.sin6_addr.s6_addr[14] = 0x45;
  addr.sin6_addr.s6_addr[15] = 0x1e;

  ret = connect(s, (struct sockaddr*)&addr, sizeof(addr));
  if (ret == -1)
  {
    err = errno;
    printf("connect failure, errno = %d\n", err);
  }
}

结果总是"连接失败,错误= 22"问题出在哪里？

Answer 1

如果你要使用链路本地地址,你必须设置sin6_scope_id到链路上的网络设备的设备指数匹配(这就是为什么你必须指定-I eth1你的ping6命令).

您可以getaddrinfo()为您完成所有艰苦的工作,包括设置范围ID(请注意%eth1地址末尾)和端口:

struct addrinfo hints = { 0 };
struct addrinfo *res;
int gai_err;
int s;

hints.ai_family = AF_INET6;
hints.ai_socktype = SOCK_STREAM;

gai_err = getaddrinfo("fe80::240:8cff:fe94:451e%eth1", "554", &hints, &res);

if (gai_err)
{
    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(gai_err));
    return 1;
}

s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);

if (s < 0) {
    perror("socket");
    return 1;
}

if (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
    perror("connect");
    return 1;
}