Merge pull request #4391 from matheusdtech/lnwire-zero-sid

lnwire: fix decoding for initial zero sid

lnwire/query_short_chan_ids.go

@@ -184,8 +184,13 @@ func decodeShortChanIDs(r io.Reader) (ShortChanIDEncoding, []ShortChannelID, err
 					"short chan ID: %v", err)
 			}
 
+			// We'll ensure that this short chan ID is greater than
+			// the last one. This is a requirement within the
+			// encoding, and if violated can aide us in detecting
+			// malicious payloads. This can only be true starting
+			// at the second chanID.
 			cid := shortChanIDs[i]
-			if cid.ToUint64() <= lastChanID.ToUint64() {
+			if i > 0 && cid.ToUint64() <= lastChanID.ToUint64() {
 				return 0, nil, ErrUnsortedSIDs{lastChanID, cid}
 			}
 			lastChanID = cid
@@ -224,6 +229,7 @@ func decodeShortChanIDs(r io.Reader) (ShortChanIDEncoding, []ShortChannelID, err
 		var (
 			shortChanIDs []ShortChannelID
 			lastChanID   ShortChannelID
+			i            int
 		)
 		for {
 			// We'll now attempt to read the next short channel ID
@@ -255,12 +261,14 @@ func decodeShortChanIDs(r io.Reader) (ShortChanIDEncoding, []ShortChannelID, err
 			// Finally, we'll ensure that this short chan ID is
 			// greater than the last one. This is a requirement
 			// within the encoding, and if violated can aide us in
-			// detecting malicious payloads.
+			// detecting malicious payloads. This can only be true
-			if cid.ToUint64() <= lastChanID.ToUint64() {
+			// starting at the second chanID.
+			if i > 0 && cid.ToUint64() <= lastChanID.ToUint64() {
 				return 0, nil, ErrUnsortedSIDs{lastChanID, cid}
 			}
 
 			lastChanID = cid
+			i++
 		}
 
 	default:

lnwire/query_short_chan_ids_test.go

@@ -49,6 +49,7 @@ var (
 // TestQueryShortChanIDsUnsorted tests that decoding a QueryShortChanID request
 // that contains duplicate or unsorted ids returns an ErrUnsortedSIDs failure.
 func TestQueryShortChanIDsUnsorted(t *testing.T) {
+
 	for _, test := range unsortedSidTests {
 		test := test
 		t.Run(test.name, func(t *testing.T) {
@@ -73,3 +74,48 @@ func TestQueryShortChanIDsUnsorted(t *testing.T) {
 		})
 	}
 }
+
+// TestQueryShortChanIDsZero ensures that decoding of a list of short chan ids
+// still works as expected when the first element of the list is zero.
+func TestQueryShortChanIDsZero(t *testing.T) {
+	testCases := []struct {
+		name     string
+		encoding ShortChanIDEncoding
+	}{
+		{
+			name:     "plain",
+			encoding: EncodingSortedPlain,
+		}, {
+			name:     "zlib",
+			encoding: EncodingSortedZlib,
+		},
+	}
+
+	testSids := []ShortChannelID{
+		NewShortChanIDFromInt(0),
+		NewShortChanIDFromInt(10),
+	}
+
+	for _, test := range testCases {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			req := &QueryShortChanIDs{
+				EncodingType: test.encoding,
+				ShortChanIDs: testSids,
+				noSort:       true,
+			}
+
+			var b bytes.Buffer
+			err := req.Encode(&b, 0)
+			if err != nil {
+				t.Fatalf("unable to encode req: %v", err)
+			}
+
+			var req2 QueryShortChanIDs
+			err = req2.Decode(bytes.NewReader(b.Bytes()), 0)
+			if err != nil {
+				t.Fatalf("unexpected decoding error: %v", err)
+			}
+		})
+	}
+}