[PATCH net-next 03/13] mptcp: skip connecting the connected address

[Mat Martineau]

From: Geliang Tang <geliangt...@gmail.com>

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 and send out the echo.

Signed-off-by: Geliang Tang <geliangt...@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martin...@linux.intel.com>
---
 net/mptcp/pm_netlink.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 53c09db08058..4b4b87803f33 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)
@@ -475,6 +493,10 @@ 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))
+               goto add_addr_echo;
+
        msk->pm.add_addr_accepted++;
        msk->pm.subflows++;
        if (msk->pm.add_addr_accepted >= add_addr_accept_max ||
@@ -494,6 +516,7 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock 
*msk)
        __mptcp_subflow_connect(sk, &local, &remote);
        spin_lock_bh(&msk->pm.lock);
 
+add_addr_echo:
        mptcp_pm_announce_addr(msk, &msk->pm.remote, true);
        mptcp_pm_nl_add_addr_send_ack(msk);
 }
-- 
2.31.0