Re: [PATCH net-next, v2] netlink: add IGMP/MLD join/leave notifications

[Hangbin Liu <liuhangbin@gmail.com>]

Hi Yuyang,
On Sun, Nov 17, 2024 at 11:11:37PM +0900, Yuyang Huang wrote:
> +static int inet_fill_ifmcaddr(struct sk_buff *skb, struct net_device *dev,
> +			      __be32 addr, int event)
> +{
> +	struct ifaddrmsg *ifm;
> +	struct nlmsghdr *nlh;
> +
> +	nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct ifaddrmsg), 0);
> +	if (!nlh)
> +		return -EMSGSIZE;
> +
> +	ifm = nlmsg_data(nlh);
> +	ifm->ifa_family = AF_INET;
> +	ifm->ifa_prefixlen = 32;
> +	ifm->ifa_flags = IFA_F_PERMANENT;
> +	ifm->ifa_scope = RT_SCOPE_LINK;

Why the IPv4 scope use RT_SCOPE_LINK,

> +static int inet6_fill_ifmcaddr(struct sk_buff *skb, struct net_device *dev,
> +			       const struct in6_addr *addr, int event)
> +{
> +	struct ifaddrmsg *ifm;
> +	struct nlmsghdr *nlh;
> +	u8 scope;
> +
> +	scope = RT_SCOPE_UNIVERSE;
> +	if (ipv6_addr_scope(addr) & IFA_SITE)
> +		scope = RT_SCOPE_SITE;

And IPv6 use RT_SCOPE_UNIVERSE by default?

> +
> +	nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct ifaddrmsg), 0);
> +	if (!nlh)
> +		return -EMSGSIZE;
> +
> +	ifm = nlmsg_data(nlh);
> +	ifm->ifa_family = AF_INET6;
> +	ifm->ifa_prefixlen = 128;
> +	ifm->ifa_flags = IFA_F_PERMANENT;
> +	ifm->ifa_scope = scope;
> +	ifm->ifa_index = dev->ifindex;
> +
> +static void inet6_ifmcaddr_notify(struct net_device *dev,
> +				  const struct in6_addr *addr, int event)
> +{
> +	struct net *net = dev_net(dev);
> +	struct sk_buff *skb;
> +	int err = -ENOBUFS;
> +
> +	skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg))
> +			+ nla_total_size(16), GFP_ATOMIC);
> +	if (!skb)
> +		goto error;
> +
> +	err = inet6_fill_ifmcaddr(skb, dev, addr, event);
> +	if (err < 0) {
> +		WARN_ON(err == -EMSGSIZE);

Not sure if we really need this WARN_ON. Wait for others comments.

Thanks
Hangbin