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linux-next/include/linux/igmp.h
Yuyang Huang 2c2b61d213 netlink: add IGMP/MLD join/leave notifications 
This change introduces netlink notifications for multicast address
changes. The following features are included:
* Addition and deletion of multicast addresses are reported using
  RTM_NEWMULTICAST and RTM_DELMULTICAST messages with AF_INET and
  AF_INET6.
* Two new notification groups: RTNLGRP_IPV4_MCADDR and
  RTNLGRP_IPV6_MCADDR are introduced for receiving these events.

This change allows user space applications (e.g., ip monitor) to
efficiently track multicast group memberships by listening for netlink
events. Previously, applications relied on inefficient polling of
procfs, introducing delays. With netlink notifications, applications
receive realtime updates on multicast group membership changes,
enabling more precise metrics collection and system monitoring. 

This change also unlocks the potential for implementing a wide range
of sophisticated multicast related features in user space by allowing
applications to combine kernel provided multicast address information
with user space data and communicate decisions back to the kernel for
more fine grained control. This mechanism can be used for various
purposes, including multicast filtering, IGMP/MLD offload, and
IGMP/MLD snooping.

Cc: Maciej Żenczykowski <maze@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Co-developed-by: Patrick Ruddy <pruddy@vyatta.att-mail.com>
Signed-off-by: Patrick Ruddy <pruddy@vyatta.att-mail.com>
Link: https://lore.kernel.org/r/20180906091056.21109-1-pruddy@vyatta.att-mail.com
Signed-off-by: Yuyang Huang <yuyanghuang@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-12-15 12:31:35 +00:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Linux NET3: Internet Group Management Protocol [IGMP]
*
* Authors:
* Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* Extended to talk the BSD extended IGMP protocol of mrouted 3.6
*/
#ifndef _LINUX_IGMP_H
#define _LINUX_IGMP_H
#include <linux/skbuff.h>
#include <linux/timer.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/refcount.h>
#include <linux/sockptr.h>
#include <uapi/linux/igmp.h>
static inline struct igmphdr *igmp_hdr(const struct sk_buff *skb)
{
return (struct igmphdr *)skb_transport_header(skb);
}
static inline struct igmpv3_report *
igmpv3_report_hdr(const struct sk_buff *skb)
{
return (struct igmpv3_report *)skb_transport_header(skb);
}
static inline struct igmpv3_query *
igmpv3_query_hdr(const struct sk_buff *skb)
{
return (struct igmpv3_query *)skb_transport_header(skb);
}
struct ip_sf_socklist {
unsigned int sl_max;
unsigned int sl_count;
struct rcu_head rcu;
__be32 sl_addr[] __counted_by(sl_max);
};
#define IP_SFBLOCK 10 /* allocate this many at once */
/* ip_mc_socklist is real list now. Speed is not argument;
this list never used in fast path code
*/
struct ip_mc_socklist {
struct ip_mc_socklist __rcu *next_rcu;
struct ip_mreqn multi;
unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */
struct ip_sf_socklist __rcu *sflist;
struct rcu_head rcu;
};
struct ip_sf_list {
struct ip_sf_list *sf_next;
unsigned long sf_count[2]; /* include/exclude counts */
__be32 sf_inaddr;
unsigned char sf_gsresp; /* include in g & s response? */
unsigned char sf_oldin; /* change state */
unsigned char sf_crcount; /* retrans. left to send */
};
struct ip_mc_list {
struct in_device *interface;
__be32 multiaddr;
unsigned int sfmode;
struct ip_sf_list *sources;
struct ip_sf_list *tomb;
unsigned long sfcount[2];
union {
struct ip_mc_list *next;
struct ip_mc_list __rcu *next_rcu;
};
struct ip_mc_list __rcu *next_hash;
struct timer_list timer;
int users;
refcount_t refcnt;
spinlock_t lock;
char tm_running;
char reporter;
char unsolicit_count;
char loaded;
unsigned char gsquery; /* check source marks? */
unsigned char crcount;
unsigned long mca_cstamp;
unsigned long mca_tstamp;
struct rcu_head rcu;
};
/* V3 exponential field decoding */
#define IGMPV3_MASK(value, nb) ((nb)>=32 ? (value) : ((1<<(nb))-1) & (value))
#define IGMPV3_EXP(thresh, nbmant, nbexp, value) \
((value) < (thresh) ? (value) : \
((IGMPV3_MASK(value, nbmant) | (1<<(nbmant))) << \
(IGMPV3_MASK((value) >> (nbmant), nbexp) + (nbexp))))
#define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value)
#define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)
static inline int ip_mc_may_pull(struct sk_buff *skb, unsigned int len)
{
if (skb_transport_offset(skb) + ip_transport_len(skb) < len)
return 0;
return pskb_may_pull(skb, len);
}
extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u8 proto);
extern int igmp_rcv(struct sk_buff *);
extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
extern int ip_mc_join_group_ssm(struct sock *sk, struct ip_mreqn *imr,
unsigned int mode);
extern int ip_mc_leave_group(struct sock *sk, struct ip_mreqn *imr);
extern void ip_mc_drop_socket(struct sock *sk);
extern int ip_mc_source(int add, int omode, struct sock *sk,
struct ip_mreq_source *mreqs, int ifindex);
extern int ip_mc_msfilter(struct sock *sk, struct ip_msfilter *msf,int ifindex);
extern int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
sockptr_t optval, sockptr_t optlen);
extern int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
sockptr_t optval, size_t offset);
extern int ip_mc_sf_allow(const struct sock *sk, __be32 local, __be32 rmt,
int dif, int sdif);
extern void ip_mc_init_dev(struct in_device *);
extern void ip_mc_destroy_dev(struct in_device *);
extern void ip_mc_up(struct in_device *);
extern void ip_mc_down(struct in_device *);
extern void ip_mc_unmap(struct in_device *);
extern void ip_mc_remap(struct in_device *);
extern void __ip_mc_dec_group(struct in_device *in_dev, __be32 addr, gfp_t gfp);
static inline void ip_mc_dec_group(struct in_device *in_dev, __be32 addr)
{
return __ip_mc_dec_group(in_dev, addr, GFP_KERNEL);
}
extern void __ip_mc_inc_group(struct in_device *in_dev, __be32 addr,
gfp_t gfp);
extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
int ip_mc_check_igmp(struct sk_buff *skb);
#endif
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