Re: [PATCH iproute2-next] iproute2: add 'ip monitor mcaddr' support

[Hangbin Liu <liuhangbin@gmail.com>]

On Sun, Nov 17, 2024 at 11:16:55PM +0900, Yuyang Huang wrote:
> Enhanced the 'ip monitor' command to track changes in IPv4 and IPv6
> multicast addresses. This update allows the command to listen for
> events related to multicast address additions and deletions by
> registering to the newly introduced RTNLGRP_IPV4_MCADDR and
> RTNLGRP_IPV6_MCADDR netlink groups.
> 
> This patch depends on the kernel patch that adds RTNLGRP_IPV4_MCADDR
> and RTNLGRP_IPV6_MCADDR being merged first.
> 
> Here is an example usage:
> 
> root@uml-x86-64:/# ip monitor mcaddr
> 8: nettest123    inet6 mcast ff01::1 scope global
> 8: nettest123    inet6 mcast ff02::1 scope global
> 8: nettest123    inet mcast 224.0.0.1 scope link
> 8: nettest123    inet6 mcast ff02::1:ff00:7b01 scope global
> Deleted 8: nettest123    inet mcast 224.0.0.1 scope link
> Deleted 8: nettest123    inet6 mcast ff02::1:ff00:7b01 scope global
> Deleted 8: nettest123    inet6 mcast ff02::1 scope global
> 
> Cc: Maciej Żenczykowski <maze@google.com>
> Cc: Lorenzo Colitti <lorenzo@google.com>
> Signed-off-by: Yuyang Huang <yuyanghuang@google.com>
> ---
>  include/uapi/linux/rtnetlink.h |  8 ++++++++
>  ip/ipaddress.c                 | 17 +++++++++++++++--
>  ip/ipmonitor.c                 | 25 ++++++++++++++++++++++++-
>  3 files changed, 47 insertions(+), 3 deletions(-)
> 
> diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
> index 4e6c8e14..ccf26bf1 100644
> --- a/include/uapi/linux/rtnetlink.h
> +++ b/include/uapi/linux/rtnetlink.h
> @@ -93,6 +93,10 @@ enum {
>  	RTM_NEWPREFIX	= 52,
>  #define RTM_NEWPREFIX	RTM_NEWPREFIX
>  
> +	RTM_NEWMULTICAST,
> +#define RTM_NEWMULTICAST RTM_NEWMULTICAST
> +	RTM_DELMULTICAST,
> +#define RTM_DELMULTICAST RTM_DELMULTICAST
>  	RTM_GETMULTICAST = 58,
>  #define RTM_GETMULTICAST RTM_GETMULTICAST
>  
> @@ -772,6 +776,10 @@ enum rtnetlink_groups {
>  #define RTNLGRP_TUNNEL		RTNLGRP_TUNNEL
>  	RTNLGRP_STATS,
>  #define RTNLGRP_STATS		RTNLGRP_STATS
> +	RTNLGRP_IPV4_MCADDR,
> +#define RTNLGRP_IPV4_MCADDR	RTNLGRP_IPV4_MCADDR
> +	RTNLGRP_IPV6_MCADDR,
> +#define RTNLGRP_IPV6_MCADDR    RTNLGRP_IPV6_MCADDR
>  	__RTNLGRP_MAX
>  };
>  #define RTNLGRP_MAX	(__RTNLGRP_MAX - 1)

No need changes for headers. Stephen will sync the headers.

> @@ -220,6 +226,8 @@ int do_ipmonitor(int argc, char **argv)
>  			lmask |= IPMON_LNEXTHOP;
>  		} else if (strcmp(*argv, "stats") == 0) {
>  			lmask |= IPMON_LSTATS;
> +		} else if (strcmp(*argv, "mcaddr") == 0) {
> +			lmask |= IPMON_LMCADDR;
>  		} else if (strcmp(*argv, "all") == 0) {
>  			prefix_banner = 1;
>  		} else if (matches(*argv, "all-nsid") == 0) {
> @@ -326,6 +334,21 @@ int do_ipmonitor(int argc, char **argv)
>  		exit(1);
>  	}
>  
> +	if (lmask & IPMON_LMCADDR) {
> +		if ((!preferred_family || preferred_family == AF_INET) &&
> +			rtnl_add_nl_group(&rth, RTNLGRP_IPV4_MCADDR) < 0) {

The rtnl_add_nl_group() should be aligned with the upper bracket. e.g.

		if ((!preferred_family || preferred_family == AF_INET) &&
		    rtnl_add_nl_group(&rth, RTNLGRP_IPV4_MCADDR) < 0) {

> +			fprintf(stderr,
> +				"Failed to add ipv4 mcaddr group to list\n");
> +			exit(1);
> +		}
> +		if ((!preferred_family || preferred_family == AF_INET6) &&
> +			rtnl_add_nl_group(&rth, RTNLGRP_IPV6_MCADDR) < 0) {

Same with this one.

Thanks
Hangbin