[MPTCP] [MPTCP][PATCH v2 mptcp-next 1/4] mptcp: skip connecting the connected address

[MPTCP] [MPTCP][PATCH v2 mptcp-next 1/4] mptcp: skip connecting the connected address

[Geliang Tang]

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

In mptcp_pm_add_addr_received, use mptcp_lookup_subflow_by_daddr to check
whether the announced address is already connected. If it is, skip
connecting this address and send out the echo.

Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
---
 net/mptcp/pm.c         |  3 ++-
 net/mptcp/pm_netlink.c | 20 +++++++++++++++++++-
 net/mptcp/protocol.h   |  2 ++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index db2ce84d250a..0d3ea9b45228 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -186,7 +186,8 @@ void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 
 	spin_lock_bh(&pm->lock);
 
-	if (!READ_ONCE(pm->accept_addr)) {
+	if (!READ_ONCE(pm->accept_addr) ||
+	    mptcp_lookup_subflow_by_daddr(&msk->conn_list, addr)) {
 		mptcp_pm_announce_addr(msk, addr, true, addr->port);
 		mptcp_pm_add_addr_send_ack(msk);
 	} else if (mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED)) {
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 55fdcb1b5281..4412a339e305 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -59,7 +59,7 @@ struct pm_nl_pernet {
 static void mptcp_pm_nl_add_addr_send_ack(struct mptcp_sock *msk);
 
 static bool addresses_equal(const struct mptcp_addr_info *a,
-			    struct mptcp_addr_info *b, bool use_port)
+			    const struct mptcp_addr_info *b, bool use_port)
 {
 	bool addr_equals = false;
 
@@ -140,6 +140,24 @@ static bool lookup_subflow_by_saddr(const struct list_head *list,
 	return false;
 }
 
+bool mptcp_lookup_subflow_by_daddr(const struct list_head *list,
+				   const 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)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 6af3e259fa05..aa44bc28c5a8 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -662,6 +662,8 @@ mptcp_pm_del_add_timer(struct mptcp_sock *msk,
 struct mptcp_pm_add_entry *
 mptcp_lookup_anno_list_by_saddr(struct mptcp_sock *msk,
 				struct mptcp_addr_info *addr);
+bool mptcp_lookup_subflow_by_daddr(const struct list_head *list,
+				   const struct mptcp_addr_info *daddr);
 
 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   const struct mptcp_addr_info *addr,
-- 
2.29.2