[RFC PATCH mptcp-next v5 04/10] Treat a socket option TCP_FASTOPEN on Lister side. Suggestion @mmartineau(MAY 22): 'Need to use ssk instead of sk in these several lines' (1 AUG): 'Since fastopen is only relevant for the initial subflow (and never with MP_JOIN). __mptcp_nmpc_socket() should give the initial subflow'

[Dmytro Shytyi <dmytro@shytyi.net>]

Treat a socket option TCP_FASTOPEN on
Lister side. Suggestion @mmartineau(MAY 22): 'Need to use ssk instead of sk
in these several lines' (1 AUG): 'Since fastopen is only relevant for the
initial subflow (and never with MP_JOIN). __mptcp_nmpc_socket() should give
the initial subflow'

Signed-off-by: Dmytro Shytyi <dmytro@shytyi.net>
---
 net/mptcp/fastopen.c | 31 +++++++++++++++++++++++++++++++
 net/mptcp/protocol.c |  4 ++--
 net/mptcp/protocol.h |  3 +++
 net/mptcp/sockopt.c  |  3 +++
 4 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c
index 0e071c988894..2633d5148dcb 100644
--- a/net/mptcp/fastopen.c
+++ b/net/mptcp/fastopen.c
@@ -54,3 +54,34 @@ int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
 	ret = -EFAULT;
 	return ret;
 }
+
+int mptcp_setsockopt_sol_tcp_fastopen(struct mptcp_sock *msk, sockptr_t optval,
+				      unsigned int optlen)
+{
+	struct sock *ssk = __mptcp_nmpc_socket(msk)->sk;
+	struct sock *sk = (struct sock *)msk;
+	struct net *net = sock_net(sk);
+	int val;
+	int ret;
+
+	ret = 0;
+
+	if (copy_from_sockptr(&val, optval, sizeof(val)))
+		return -EFAULT;
+
+	lock_sock(sk);
+	lock_sock(ssk);
+
+	if (val >= 0 && ((1 << ssk->sk_state) & (TCPF_CLOSE |
+	    TCPF_LISTEN))) {
+		tcp_fastopen_init_key_once(net);
+		fastopen_queue_tune(ssk, val);
+	} else {
+		ret = -EINVAL;
+	}
+
+	release_sock(ssk);
+	release_sock(sk);
+
+	return ret;
+}
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 6bbf1b86465d..af99a03021c9 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3474,8 +3474,8 @@ static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
 	__mptcp_do_fallback(msk);
 }
 
-static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
-				int addr_len, int flags)
+int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+			 int addr_len, int flags)
 {
 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
 	struct mptcp_subflow_context *subflow;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ad51910f1cc9..ef8330d5a9b5 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -835,11 +835,14 @@ void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
 void mptcp_event_addr_announced(const struct sock *ssk, const struct mptcp_addr_info *info);
 void mptcp_event_addr_removed(const struct mptcp_sock *msk, u8 id);
 bool mptcp_userspace_pm_active(const struct mptcp_sock *msk);
+int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, int addr_len, int flags);
 
 // Fast Open Mechanism functions begin
 int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
 			   size_t len, struct mptcp_sock *msk,
 			   size_t *copied);
+int mptcp_setsockopt_sol_tcp_fastopen(struct mptcp_sock *msk, sockptr_t optval,
+				      unsigned int optlen);
 // Fast Open Mechanism functions end
 
 static inline bool mptcp_pm_should_add_signal(struct mptcp_sock *msk)
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 423d3826ca1e..f62f0d63b8e6 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -559,6 +559,7 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		case TCP_NOTSENT_LOWAT:
 		case TCP_TX_DELAY:
 		case TCP_INQ:
+		case TCP_FASTOPEN:
 			return true;
 		}
 
@@ -796,6 +797,8 @@ static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 		return mptcp_setsockopt_sol_tcp_nodelay(msk, optval, optlen);
 	case TCP_DEFER_ACCEPT:
 		return mptcp_setsockopt_sol_tcp_defer(msk, optval, optlen);
+	case TCP_FASTOPEN:
+		return mptcp_setsockopt_sol_tcp_fastopen(msk, optval, optlen);
 	}
 
 	return -EOPNOTSUPP;
-- 
2.25.1