/net/bridge/br_arp_nd_proxy.c

一、介绍

br_arp_nd_proxy.c包括网桥上的ARP协议与IP6的邻居发现协议相关操作。

二、重要结构体

（一）net_bridge

见br.c解析

（二）net_bridge_port

网桥端口数据结构，代表某一个端口。

struct net_bridge_port {
	struct net_bridge		*br;
	struct net_device		*dev;
	struct list_head		list;

	unsigned long			flags;
#ifdef CONFIG_BRIDGE_VLAN_FILTERING
	struct net_bridge_vlan_group	__rcu *vlgrp;
#endif
	struct net_bridge_port		__rcu *backup_port;

	/* STP */
	u8				priority;
	u8				state;
	u16				port_no;
	unsigned char			topology_change_ack;
	unsigned char			config_pending;
	port_id				port_id;
	port_id				designated_port;
	bridge_id			designated_root;
	bridge_id			designated_bridge;
	u32				path_cost;
	u32				designated_cost;
	unsigned long			designated_age;

	struct timer_list		forward_delay_timer;
	struct timer_list		hold_timer;
	struct timer_list		message_age_timer;
	struct kobject			kobj;
	struct rcu_head			rcu;

#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
	struct bridge_mcast_own_query	ip4_own_query;
	struct timer_list		ip4_mc_router_timer;
	struct hlist_node		ip4_rlist;
#if IS_ENABLED(CONFIG_IPV6)
	struct bridge_mcast_own_query	ip6_own_query;
	struct timer_list		ip6_mc_router_timer;
	struct hlist_node		ip6_rlist;
#endif /* IS_ENABLED(CONFIG_IPV6) */
	u32				multicast_eht_hosts_limit;
	u32				multicast_eht_hosts_cnt;
	unsigned char			multicast_router;
	struct bridge_mcast_stats	__percpu *mcast_stats;
	struct hlist_head		mglist;
#endif

#ifdef CONFIG_SYSFS
	char				sysfs_name[IFNAMSIZ];
#endif

#ifdef CONFIG_NET_POLL_CONTROLLER
	struct netpoll			*np;
#endif
#ifdef CONFIG_NET_SWITCHDEV
	int				offload_fwd_mark;
#endif
	u16				group_fwd_mask;
	u16				backup_redirected_cnt;

	struct bridge_stp_xstats	stp_xstats;
};

（三）sk_buff

sk_buff的定义在/include/linux/skbuff.h里，内容发非常多。

简单的说，一个skb_buff变量就代表了一个数据报，可以在系统中流转。完整地包含了一个数据报所需的全部内容和相关信息与属性。

三、函数

1. br_recalculate_neigh_suppress_enabled：设置是否允许进行流控。
   void br_recalculate_neigh_suppress_enabled(struct net_bridge *br)

2. br_arp_send：通过src_ip和dest_ip数据发送ARP报文。

static void br_arp_send(struct net_bridge *br, struct net_bridge_port *p,
			struct net_device *dev, __be32 dest_ip, __be32 src_ip,
			const unsigned char *dest_hw,
			const unsigned char *src_hw,
			const unsigned char *target_hw,
			__be16 vlan_proto, u16 vlan_tci)

3. br_chk_addr_ip：判断指定设备于IP是否相符。
   static int br_chk_addr_ip(struct net_device *dev, struct netdev_nested_priv *priv)

4. br_is_local_ip：检查IP是否是该设备或上层设备的IP。
   static bool br_is_local_ip(struct net_device *dev, __be32 ip)

5. br_do_proxy_suppress_arp：向支持BR_NEIGH_SUPPRESS或BR_PROXYARP_WIFI的端口发送ARP报文。

void br_do_proxy_suppress_arp(struct sk_buff *skb, struct net_bridge *br,
			      u16 vid, struct net_bridge_port *p)

6. br_is_nd_neigh_msg：打开CONFIG_IPV6才有效。判断是否是IP6的邻居发现协议。
   struct nd_msg *br_is_nd_neigh_msg(struct sk_buff *skb, struct nd_msg *msg)

7. br_nd_send：发送IP6的邻居发现协议报文。

static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
		       struct sk_buff *request, struct neighbour *n,
		       __be16 vlan_proto, u16 vlan_tci, struct nd_msg *ns)

8. br_chk_addr_ip6：检查设备与IP6的地址是否相符。
   static int br_chk_addr_ip6(struct net_device *dev, struct netdev_nested_priv *priv)

9. br_is_local_ip6：检查IP6地址是否是本设备地址或上层设备地址。
   static bool br_is_local_ip6(struct net_device *dev, struct in6_addr *addr)

10. br_do_suppress_nd：发送IP6的流控帧。

void br_do_suppress_nd(struct sk_buff *skb, struct net_bridge *br,
		       u16 vid, struct net_bridge_port *p, struct nd_msg *msg)