sendmsg如何从指定接口(网卡)发数据

[爱碎碎念]

环境:linux

ssize_t sendmsg (int sockfd, struct msghdr *msg, int flags);

其中sockfd=socket(AF_INET6, SOCK_RAW, 88 );/* 88 是自己定义的 */

sendmsg可以带辅助数据,我使用的辅助数据类型cmsg_type = IPV6_PKTINFO

而struct in6_pktinfo中有ipi6_ifindex成员,我想使用它来接定发送的接口(即网卡).

可实际上发送的数据确从所有接口发送出去.也就是指定无效.

恳请达人给予解答.谢谢.

-------
在使用recvmsg函数接收数据并判断是从哪个接口接收到的数据时,也是使用这种辅助数据,刚开使未成功.

后来设置了选项setsockopt (sockfd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on, sizeof(on));就可以了.

我怀疑是不是对于sendmsg也需要设置什么选项.

怕上面说的不清楚,代码也贴上来了.

int cn_send (struct in6_addr *src, struct in6_addr *dst,
		struct cn_interface *ci, struct cn_header *ch)
{
	struct sockaddr_in6 sa6_dst;
	memset (&sa6_dst, 0, sizeof (sa6_dst));
	sa6_dst.sin6_family = AF_INET6;
	memcpy (&sa6_dst.sin6_addr, dst, sizeof (struct in6_addr));

	u_char cmsgbuf[CMSG_SPACE(sizeof (struct in6_pktinfo))];
	struct cmsghdr *scmsgp;
	scmsgp = (struct cmsghdr *)cmsgbuf;
	struct in6_pktinfo *pktinfo;
	pktinfo = (struct in6_pktinfo *)(CMSG_DATA(scmsgp));

	scmsgp->cmsg_len = CMSG_LEN (sizeof (struct in6_pktinfo));
	scmsgp->cmsg_level = IPPROTO_IPV6;
	scmsgp->cmsg_type = IPV6_PKTINFO;
	memset (&pktinfo->ipi6_addr, 0, sizeof (struct in6_addr));
	pktinfo->ipi6_ifindex = ci->ifindex;

	struct iovec iov;
	iov.iov_base = (void *)ch;
	iov.iov_len = ntohs (ch->length);

	struct msghdr smsghdr;
	memset (&smsghdr, 0, sizeof (struct msghdr));
	smsghdr.msg_name = (void *)&sa6_dst;
	smsghdr.msg_namelen = sizeof (struct sockaddr_in6);
	smsghdr.msg_iov = &iov;
	smsghdr.msg_iovlen = 1;
	smsghdr.msg_control = NULL;
	smsghdr.msg_controllen = 0;
	smsghdr.msg_flags = 0;

	int n;
	if ((n = sendmsg (sockfd, &smsghdr, 0)) < 0)
	{
		perror("sendmsg");
		return -1;
	}
	.........
	return 0;
}

[爱碎碎念]

贴子沉了,顶一下下.

[shiweifu]

帮顶了！

[爱碎碎念]

[Quote=引用 2 楼 shiweifu 的回复:]
帮顶了！
[/Quote]
谢谢!