p2p: revert reason decoding back to using array

p2p/peer.go

@@ -343,11 +343,11 @@ func (p *Peer) handle(msg Msg) error {
 		case <-p.closed:
 		}
 	case msg.Code == discMsg:
+		var reason [1]DiscReason
 		// This is the last message. We don't need to discard or
 		// check errors because, the connection will be closed after it.
-		var m struct{ R DiscReason }
-		rlp.Decode(msg.Payload, &m)
-		return m.R
+		rlp.Decode(msg.Payload, &reason)
+		return reason[0]
 	case msg.Code < baseProtocolLength:
 		// ignore other base protocol messages
 		return msg.Discard()

p2p/peer_test.go

@@ -17,9 +17,12 @@
 package p2p
 
 import (
+	"bytes"
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"github.com/autonity/autonity/rlp"
+	"github.com/stretchr/testify/require"
 	"math/rand"
 	"net"
 	"reflect"
@@ -360,3 +363,15 @@ func TestMatchProtocols(t *testing.T) {
 		}
 	}
 }
+
+func TestDiscReasonDecoding(t *testing.T) {
+	// as it is encoded func (t *rlpxTransport) close(err error) in transport.go
+	var payload bytes.Buffer
+	err := rlp.Encode(&payload, []DiscReason{DiscQuitting})
+	require.NoError(t, err)
+
+	p := &Peer{}
+	err = p.handle(Msg{Code: discMsg, Payload: bytes.NewReader(payload.Bytes())})
+	t.Log(err)
+	require.True(t, errors.Is(err, DiscQuitting))
+}