[MPTCP][PATCH mptcp-next 4/9] mptcp: register ipv4 addr notifier

[Geliang Tang <geliangtang@gmail.com>]

This patch registered a ipv4 addr notifier, named mptcp_pm_addr4_notifier,
to deal with the events of net device UP, DOWN and CHANGE, and skip the
loopback device.

Save the ipv4 address, and pass it to the event handler.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 net/mptcp/pm_fullmesh.c | 49 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/net/mptcp/pm_fullmesh.c b/net/mptcp/pm_fullmesh.c
index b27f13a031e3..7c2d2b23fac3 100644
--- a/net/mptcp/pm_fullmesh.c
+++ b/net/mptcp/pm_fullmesh.c
@@ -3,6 +3,7 @@
 #define pr_fmt(fmt) "MPTCP: " fmt
 
 #include <linux/kernel.h>
+#include <linux/inetdevice.h>
 #include <net/tcp.h>
 #include <net/netns/generic.h>
 #include <net/mptcp.h>
@@ -130,6 +131,45 @@ void mptcp_pm_fm_data_init(struct mptcp_sock *msk)
 	WRITE_ONCE(pm->accept_subflow, MPTCP_PM_FM_MAX_ADDR);
 }
 
+static int mptcp_fm_cmd_mod_addr(struct net *net, const struct mptcp_addr_info *addr)
+{
+	return 0;
+}
+
+static void addr_event_handler(unsigned long event, struct net *net,
+			       struct mptcp_addr_info *addr)
+{
+	if (event == NETDEV_CHANGE)
+		mptcp_fm_cmd_mod_addr(net, addr);
+}
+
+static int mptcp_pm_addr4_event(struct notifier_block *this,
+				unsigned long event, void *ptr)
+{
+	const struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
+	struct net *net = dev_net(ifa->ifa_dev->dev);
+	struct mptcp_addr_info addr = { 0 };
+
+	if (!(event == NETDEV_UP || event == NETDEV_DOWN || event == NETDEV_CHANGE))
+		goto out;
+
+	if (ifa->ifa_scope > RT_SCOPE_LINK ||
+	    ipv4_is_loopback(ifa->ifa_local))
+		goto out;
+
+	addr.family = AF_INET;
+	addr.addr.s_addr = ifa->ifa_local;
+
+	addr_event_handler(event, net, &addr);
+
+out:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block mptcp_pm_addr4_notifier = {
+	.notifier_call = mptcp_pm_addr4_event,
+};
+
 static int __net_init pm_fm_init_net(struct net *net)
 {
 	struct pm_fm_pernet *pernet = net_generic(net, pm_fm_pernet_id);
@@ -177,4 +217,13 @@ void __init mptcp_pm_fm_init(void)
 	ret = register_pernet_subsys(&mptcp_pm_fm_pernet_ops);
 	if (ret)
 		return;
+
+	ret = register_inetaddr_notifier(&mptcp_pm_addr4_notifier);
+	if (ret)
+		goto err_reg_inetaddr;
+
+	return;
+
+err_reg_inetaddr:
+	unregister_pernet_subsys(&mptcp_pm_fm_pernet_ops);
 }
-- 
2.31.1