[MPTCP] [MPTCP][PATCH mptcp-next 1/4] mptcp: skip connecting the connected address

[Geliang Tang <geliangtang at gmail.com>]

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This patch added a new helper named lookup_subflow_by_daddr to find
whether the destination address is in the msk's conn_list.

In mptcp_pm_nl_add_addr_received, use lookup_subflow_by_daddr to check
whether the announced address is already connected. If it is, skip
connecting this address.

Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
---
 net/mptcp/pm_netlink.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 55fdcb1b5281..9396f9635231 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -140,6 +140,24 @@ static bool lookup_subflow_by_saddr(const struct list_head *list,
 	return false;
 }
 
+static bool lookup_subflow_by_daddr(const struct list_head *list,
+				    struct mptcp_addr_info *daddr)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_addr_info cur;
+	struct sock_common *skc;
+
+	list_for_each_entry(subflow, list, node) {
+		skc = (struct sock_common *)mptcp_subflow_tcp_sock(subflow);
+
+		remote_address(skc, &cur);
+		if (addresses_equal(&cur, daddr, daddr->port))
+			return true;
+	}
+
+	return false;
+}
+
 static struct mptcp_pm_addr_entry *
 select_local_address(const struct pm_nl_pernet *pernet,
 		     struct mptcp_sock *msk)
@@ -476,6 +494,10 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
 	pr_debug("accepted %d:%d remote family %d",
 		 msk->pm.add_addr_accepted, add_addr_accept_max,
 		 msk->pm.remote.family);
+
+	if (lookup_subflow_by_daddr(&msk->conn_list, &msk->pm.remote))
+		return;
+
 	msk->pm.add_addr_accepted++;
 	msk->pm.subflows++;
 	if (msk->pm.add_addr_accepted >= add_addr_accept_max ||
-- 
2.29.2