[MPTCP] [PATCH mptcp-next v2 04/12] mptcp: Add mptcp_close_state() helper

[MPTCP] [PATCH mptcp-next v2 04/12] mptcp: Add mptcp_close_state() helper

[Mat Martineau]

[-- Attachment #1: Type: text/plain, Size: 1579 bytes --]

This will be used to transition to the appropriate state on close and
determine if a DATA_FIN needs to be sent for that state transition.

Signed-off-by: Mat Martineau <mathew.j.martineau(a)linux.intel.com>
---
 net/mptcp/protocol.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 84087982367f..35b93ffeebc3 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1424,6 +1424,33 @@ static void mptcp_subflow_shutdown(struct sock *ssk, int how,
 	release_sock(ssk);
 }
 
+static const unsigned char new_state[16] = {
+  /* current state:        new state:      action:	*/
+  [0 /* (Invalid) */]	= TCP_CLOSE,
+  [TCP_ESTABLISHED]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_SYN_SENT]	= TCP_CLOSE,
+  [TCP_SYN_RECV]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_FIN_WAIT1]	= TCP_FIN_WAIT1,
+  [TCP_FIN_WAIT2]	= TCP_FIN_WAIT2,
+  [TCP_TIME_WAIT]	= TCP_CLOSE,	/* should not happen ! */
+  [TCP_CLOSE]		= TCP_CLOSE,
+  [TCP_CLOSE_WAIT]	= TCP_LAST_ACK  | TCP_ACTION_FIN,
+  [TCP_LAST_ACK]	= TCP_LAST_ACK,
+  [TCP_LISTEN]		= TCP_CLOSE,
+  [TCP_CLOSING]		= TCP_CLOSING,
+  [TCP_NEW_SYN_RECV]	= TCP_CLOSE,	/* should not happen ! */
+};
+
+static int mptcp_close_state(struct sock *sk)
+{
+	int next = (int)new_state[sk->sk_state];
+	int ns = next & TCP_STATE_MASK;
+
+	inet_sk_state_store(sk, ns);
+
+	return next & TCP_ACTION_FIN;
+}
+
 static void mptcp_close(struct sock *sk, long timeout)
 {
 	struct mptcp_subflow_context *subflow, *tmp;
-- 
2.27.0