From 1e457b659989478004329c2f3a82b5ac67b32cbf Mon Sep 17 00:00:00 2001
From: Anton Evangelatov <anton.evangelatov@gmail.com>
Date: Thu, 22 Feb 2018 11:41:06 +0100
Subject: [PATCH] p2p: don't send DiscReason when using net.Pipe (#16004)

---
 p2p/rlpx.go      | 10 ++++++++--
 p2p/rlpx_test.go | 38 +++++++++++++++++++++++++++++++++++---
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index 24037ecc13..e65a0b6047 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -108,8 +108,14 @@ func (t *rlpx) close(err error) {
 	// Tell the remote end why we're disconnecting if possible.
 	if t.rw != nil {
 		if r, ok := err.(DiscReason); ok && r != DiscNetworkError {
-			t.fd.SetWriteDeadline(time.Now().Add(discWriteTimeout))
-			SendItems(t.rw, discMsg, r)
+			// rlpx tries to send DiscReason to disconnected peer
+			// if the connection is net.Pipe (in-memory simulation)
+			// it hangs forever, since net.Pipe does not implement
+			// a write deadline. Because of this only try to send
+			// the disconnect reason message if there is no error.
+			if err := t.fd.SetWriteDeadline(time.Now().Add(discWriteTimeout)); err == nil {
+				SendItems(t.rw, discMsg, r)
+			}
 		}
 	}
 	t.fd.Close()
diff --git a/p2p/rlpx_test.go b/p2p/rlpx_test.go
index f4cefa650b..bca4604021 100644
--- a/p2p/rlpx_test.go
+++ b/p2p/rlpx_test.go
@@ -156,14 +156,18 @@ func TestProtocolHandshake(t *testing.T) {
 		node1   = &discover.Node{ID: discover.PubkeyID(&prv1.PublicKey), IP: net.IP{5, 6, 7, 8}, TCP: 44}
 		hs1     = &protoHandshake{Version: 3, ID: node1.ID, Caps: []Cap{{"c", 1}, {"d", 3}}}
 
-		fd0, fd1 = net.Pipe()
-		wg       sync.WaitGroup
+		wg sync.WaitGroup
 	)
 
+	fd0, fd1, err := tcpPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	wg.Add(2)
 	go func() {
 		defer wg.Done()
-		defer fd1.Close()
+		defer fd0.Close()
 		rlpx := newRLPX(fd0)
 		remid, err := rlpx.doEncHandshake(prv0, node1)
 		if err != nil {
@@ -597,3 +601,31 @@ func TestHandshakeForwardCompatibility(t *testing.T) {
 		t.Errorf("ingress-mac('foo') mismatch:\ngot %x\nwant %x", fooIngressHash, wantFooIngressHash)
 	}
 }
+
+// tcpPipe creates an in process full duplex pipe based on a localhost TCP socket
+func tcpPipe() (net.Conn, net.Conn, error) {
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return nil, nil, err
+	}
+	defer l.Close()
+
+	var aconn net.Conn
+	aerr := make(chan error, 1)
+	go func() {
+		var err error
+		aconn, err = l.Accept()
+		aerr <- err
+	}()
+
+	dconn, err := net.Dial("tcp", l.Addr().String())
+	if err != nil {
+		<-aerr
+		return nil, nil, err
+	}
+	if err := <-aerr; err != nil {
+		dconn.Close()
+		return nil, nil, err
+	}
+	return aconn, dconn, nil
+}