From c18a52bd74bddfc639968b96e4c2f2a2335c7565 Mon Sep 17 00:00:00 2001
From: Jason <xjasonlyu@gmail.com>
Date: Fri, 4 Oct 2019 21:12:00 +0800
Subject: [PATCH] core: process refused TCP data immediately once the
 connection is ready

If the first TCP data chunk was refused, perhaps due to the
connection was under connecting state (it's almost always the
case), waiting for timers to process the refused data would
introduce a ~250ms (TCP_FAST_INTERVAL) delay for the connection.
(from eycorsican/go-tun2socks)
---
 core/c/include/lwip/tcp.h |  2 ++
 core/tcp_conn.go          | 10 +++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)
 mode change 100644 => 100755 core/c/include/lwip/tcp.h
 mode change 100644 => 100755 core/tcp_conn.go

diff --git a/core/c/include/lwip/tcp.h b/core/c/include/lwip/tcp.h
old mode 100644
new mode 100755
index 8c9ba98..24a7f12
--- a/core/c/include/lwip/tcp.h
+++ b/core/c/include/lwip/tcp.h
@@ -479,6 +479,8 @@ err_t            tcp_output  (struct tcp_pcb *pcb);
 
 err_t            tcp_tcp_get_tcp_addrinfo(struct tcp_pcb *pcb, int local, ip_addr_t *addr, u16_t *port);
 
+err_t             tcp_process_refused_data(struct tcp_pcb *pcb);
+
 #define tcp_dbg_get_tcp_state(pcb) ((pcb)->state)
 
 /* for compatibility with older implementation */
diff --git a/core/tcp_conn.go b/core/tcp_conn.go
old mode 100644
new mode 100755
index 620f27d..6b87298
--- a/core/tcp_conn.go
+++ b/core/tcp_conn.go
@@ -64,7 +64,7 @@ type tcpConn struct {
 	localAddr     *net.TCPAddr
 	connKeyArg    unsafe.Pointer
 	connKey       uint32
-	canWrite      *sync.Cond // Condition variable to implement TCP back pressure.
+	canWrite      *sync.Cond // Condition variable to implement TCP backpressure.
 	state         tcpConnState
 	sndPipeReader *io.PipeReader
 	sndPipeWriter *io.PipeWriter
@@ -116,6 +116,12 @@ func newTCPConn(pcb *C.struct_tcp_pcb, handler TCPConnHandler) (TCPConn, error)
 			conn.Lock()
 			conn.state = tcpConnected
 			conn.Unlock()
+
+			lwipMutex.Lock()
+			if pcb.refused_data != nil {
+				C.tcp_process_refused_data(pcb)
+			}
+			lwipMutex.Unlock()
 		}
 	}()
 
@@ -133,11 +139,9 @@ func (conn *tcpConn) LocalAddr() net.Addr {
 func (conn *tcpConn) SetDeadline(t time.Time) error {
 	return nil
 }
-
 func (conn *tcpConn) SetReadDeadline(t time.Time) error {
 	return nil
 }
-
 func (conn *tcpConn) SetWriteDeadline(t time.Time) error {
 	return nil
 }