Prevent doom loop on broken RPC frames

rpc/bridge.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/diodechain/diode_client/config"
 	"github.com/diodechain/diode_client/edge"
+	"github.com/diodechain/diode_client/rlp"
 )
 
 var (
@@ -265,6 +266,16 @@ func (client *Client) isAllowlisted(port *config.Port, addr Address) bool {
 
 // handleInboundMessage handle inbound message
 func (client *Client) handleInboundMessage(msg edge.Message) {
+	// If message framing is broken, the payload will not be valid RLP.
+	// This is non-recoverable because we won't be able to find the beginning of
+	// the next frame again, so close the connection to prevent a loop.
+	if err := validateRLPMessage(msg.Buffer); err != nil {
+		client.Log().Error("Invalid RLP frame received, closing connection: %v", err)
+		client.Log().Debug("Invalid RLP data: %x", msg.Buffer)
+		client.Close()
+		return
+	}
+
 	if msg.IsResponse() {
 		defer client.timer.profile(time.Now(), "handleResponse")
 
@@ -320,6 +331,34 @@ func (client *Client) handleInboundMessage(msg edge.Message) {
 	client.handleInboundRequest(inboundRequest)
 }
 
+func validateRLPMessage(b []byte) error {
+	k, content, rest, err := rlp.Split(b)
+	if err != nil {
+		return err
+	}
+	if len(rest) != 0 {
+		return rlp.ErrMoreThanOneValue
+	}
+	return validateRLPValue(k, content)
+}
+
+func validateRLPValue(k rlp.Kind, content []byte) error {
+	if k != rlp.List {
+		return nil
+	}
+	for len(content) > 0 {
+		innerKind, innerContent, rest, err := rlp.Split(content)
+		if err != nil {
+			return err
+		}
+		if err := validateRLPValue(innerKind, innerContent); err != nil {
+			return err
+		}
+		content = rest
+	}
+	return nil
+}
+
 // recvMessageLoop infinite loop to read message from server
 func (client *Client) recvMessageLoop() {
 	msgBuffer := make(chan edge.Message, 20)

rpc/bridge_inbound_test.go

@@ -0,0 +1,94 @@
+// Diode Network Client
+// Copyright 2021 Diode
+// Licensed under the Diode License, Version 1.1
+package rpc
+
+import (
+	"testing"
+
+	"github.com/diodechain/diode_client/config"
+	"github.com/diodechain/diode_client/edge"
+	"github.com/diodechain/diode_client/rlp"
+)
+
+func TestHandleInboundMessage_ClosesOnInvalidRLP(t *testing.T) {
+	cfg := testConfig()
+	config.AppConfig = cfg
+	pool := NewPool()
+	client := NewClient("localhost:0", nil, cfg, pool)
+
+	// 0xb8 indicates a long string with 1 byte length-of-length, but the length byte is missing.
+	msg := edge.Message{Len: 1, Buffer: []byte{0xb8}}
+	client.handleInboundMessage(msg)
+
+	if !client.Closed() {
+		t.Fatalf("expected client to be closed on invalid RLP frame")
+	}
+}
+
+func TestHandleInboundMessage_DoesNotCloseOnValidUnsupportedRequest(t *testing.T) {
+	cfg := testConfig()
+	config.AppConfig = cfg
+	pool := NewPool()
+	client := NewClient("localhost:0", nil, cfg, pool)
+
+	buf, err := rlp.EncodeToBytes([]interface{}{[]byte("not-a-known-rpc")})
+	if err != nil {
+		t.Fatalf("failed to encode rlp: %v", err)
+	}
+
+	msg := edge.Message{Len: len(buf), Buffer: buf}
+	client.handleInboundMessage(msg)
+
+	if client.Closed() {
+		t.Fatalf("did not expect client to be closed on a valid but unsupported request")
+	}
+}
+
+func TestHandleInboundMessage_ClosesOnBrokenFrameFromLog(t *testing.T) {
+	cfg := testConfig()
+	config.AppConfig = cfg
+	pool := NewPool()
+	client := NewClient("localhost:0", nil, cfg, pool)
+
+	// Reported by customer as a doom-loop trigger; parsing indicates framing is broken.
+	// The message contains extra/truncated data and must be treated as non-recoverable.
+	buf := []byte{
+		0xf9, 0x01, 0x89, 0x84, 0x01, 0x00, 0x00, 0x01, 0xf9, 0x01, 0x81, 0x88, 0x72, 0x65, 0x73, 0x70,
+		0x6f, 0x6e, 0x73, 0x65, 0xf9, 0x01, 0x53, 0xec, 0x8a, 0x62, 0x6c, 0x6f, 0x63, 0x6b, 0x5f, 0x68,
+		0x61, 0x73, 0x68, 0xa0, 0x00, 0x00, 0x04, 0xaf, 0x7c, 0xc9, 0x8c, 0x99, 0xd0, 0xa0, 0xa8, 0x6d,
+		0xaf, 0x6a, 0xbd, 0x9b, 0x16, 0xc7, 0x2d, 0xdc, 0xed, 0x51, 0x56, 0x5a, 0x86, 0x23, 0x50, 0x62,
+		0x24, 0xd5, 0x08, 0x57, 0xf8, 0x53, 0x8f, 0x6d, 0x69, 0x6e, 0x65, 0x72, 0x5f, 0x73, 0x69, 0x67,
+		0x6e, 0x61, 0x74, 0x75, 0x72, 0x65, 0xb8, 0x41, 0x01, 0x4e, 0x5e, 0x3d, 0x1a, 0x8b, 0xd8, 0x3b,
+		0xf5, 0x90, 0x4d, 0xe9, 0xf1, 0x53, 0x58, 0x94, 0xc5, 0x40, 0xf6, 0x9c, 0x26, 0x95, 0x36, 0x07,
+		0x48, 0x62, 0x6d, 0xc6, 0x81, 0x0b, 0x03, 0x8b, 0x06, 0x1a, 0x6d, 0x29, 0x5b, 0xe9, 0xd9, 0x62,
+		0x4d, 0x0b, 0x8c, 0x6d, 0x4b, 0xba, 0x3d, 0x4e, 0xdc, 0x46, 0x4e, 0x79, 0x2f, 0xec, 0x14, 0xc7,
+		0xbd, 0x85, 0x77, 0xe7, 0x11, 0x6b, 0x2f, 0xc9, 0x36, 0x56, 0xe3, 0x85, 0x6e, 0x6f, 0x6e, 0x63,
+		0x65, 0x9c, 0x22, 0x49, 0xc2, 0xa7, 0x73, 0x26, 0x59, 0x7b, 0x2e, 0x01, 0x2e, 0x8e, 0x5f, 0xd9,
+		0x1a, 0x9f, 0xcf, 0x4a, 0xd0, 0x93, 0x91, 0xf4, 0xd3, 0x8b, 0x27, 0xfd, 0x32, 0x34, 0xcb, 0x86,
+		0x6e, 0x75, 0x6d, 0x62, 0x65, 0x72, 0x83, 0x9a, 0x28, 0x73, 0xf0, 0x8e, 0x70, 0x72, 0x65, 0x76,
+		0x69, 0x6f, 0x75, 0x73, 0x5f, 0x62, 0x6c, 0x6f, 0x63, 0x6b, 0xa0, 0x00, 0x00, 0x04, 0xad, 0xb4,
+		0x33, 0xa9, 0x67, 0x07, 0x8e, 0x8f, 0xd4, 0x1d, 0x5b, 0x20, 0x81, 0x31, 0x50, 0x70, 0xfb, 0x18,
+		0xf9, 0x6b, 0x1d, 0x9c, 0xd4, 0xa3, 0xce, 0xbf, 0x59, 0x0f, 0x8c, 0xec, 0x8a, 0x73, 0x74, 0x61,
+		0x74, 0x65, 0x5f, 0x68, 0x61, 0x73, 0x68, 0xa0, 0x2e, 0x49, 0x56, 0x87, 0x0c, 0xa5, 0x96, 0xa4,
+		0x92, 0x6d, 0x57, 0xfe, 0xa5, 0xee, 0x06, 0x8a, 0x0f, 0x6d, 0xfd, 0x5e, 0x8d, 0x62, 0xbc, 0x5b,
+		0x35, 0x6b, 0x80, 0x0a, 0xe4, 0x06, 0x18, 0x06, 0xcf, 0x89, 0x74, 0x69, 0x6d, 0x65, 0x73, 0x74,
+		0x61, 0x6d, 0x70, 0x84, 0x69, 0x35, 0x70, 0xd4, 0xf2, 0x90, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x61,
+		0x63, 0x74, 0x69, 0x6f, 0x6e, 0x5f, 0x68, 0x61, 0x73, 0x68, 0xa0, 0xe7, 0xaf, 0x85, 0xcf, 0x72,
+		0x40, 0xe4, 0x4d, 0x5d, 0xb3, 0x3a, 0xfa, 0x4e, 0x4e, 0x0a, 0xed, 0x10, 0x23, 0x71, 0xab, 0x7b,
+		0x23, 0x8c, 0xc0, 0x3f, 0xec, 0x75, 0xe0, 0x0a, 0xf9, 0x8a, 0xc2, 0xa1, 0x02, 0x10, 0x07, 0xad,
+		0xc7, 0xe9, 0xd3, 0x3f, 0xec, 0x5a, 0xab, 0x31, 0xf8, 0x83, 0x29, 0x30, 0xc1, 0x60, 0x1b, 0x64,
+		0x9a, 0x6c, 0xa0, 0x86, 0x48, 0x9a, 0x45, 0xc6, 0xe7, 0x6b, 0x3c, 0xb8, 0x32,
+	}
+
+	if err := validateRLPMessage(buf); err == nil {
+		t.Fatalf("expected invalid RLP for reported frame")
+	}
+
+	msg := edge.Message{Len: 398, Buffer: buf}
+	client.handleInboundMessage(msg)
+
+	if !client.Closed() {
+		t.Fatalf("expected client to be closed for reported broken frame")
+	}
+}