Merge pull request #7649 from morehouse/fuzz_lnwire_signature

lnwire: signature parsing/conversion fuzz tests

docs/release-notes/release-notes-0.17.0.md

@@ -54,6 +54,11 @@ unlock or create.
   `github.com/golang/protobuf/jsonpb`
   module](https://github.com/lightningnetwork/lnd/pull/7659).
 
+## Testing
+
+* [Added fuzz tests](https://github.com/lightningnetwork/lnd/pull/7649) for
+  signature parsing and conversion.
+
 # Contributors (Alphabetical Order)
 
 * Carla Kirk-Cohen
@@ -62,6 +67,7 @@ unlock or create.
 * Erik Arvstedt
 * hieblmi
 * Jordi Montes
+* Matt Morehouse
 * Michael Street
 * Oliver Gugger
 * ziggie1984

lnwire/fuzz_test.go

@@ -822,3 +822,60 @@ func FuzzCustomMessage(f *testing.F) {
 		harness(t, data)
 	})
 }
+
+// FuzzParseRawSignature tests that our DER-encoded signature parsing does not
+// panic for arbitrary inputs and that serializing and reparsing the signatures
+// does not mutate them.
+func FuzzParseRawSignature(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		sig, err := NewSigFromRawSignature(data)
+		if err != nil {
+			return
+		}
+
+		sig2, err := NewSigFromRawSignature(sig.ToSignatureBytes())
+		if err != nil {
+			t.Fatalf("failed to reparse signature: %v", err)
+		}
+
+		if !reflect.DeepEqual(sig, sig2) {
+			t.Fatalf("signature mismatch: %v != %v", sig, sig2)
+		}
+	})
+}
+
+// FuzzConvertFixedSignature tests that conversion of fixed 64-byte signatures
+// to DER-encoded signatures does not panic and that parsing and reconverting
+// the signatures does not mutate them.
+func FuzzConvertFixedSignature(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var sig Sig
+		if len(data) > len(sig) {
+			return
+		}
+		copy(sig[:], data)
+
+		derSig, err := sig.ToSignature()
+		if err != nil {
+			return
+		}
+
+		sig2, err := NewSigFromSignature(derSig)
+		if err != nil {
+			t.Fatalf("failed to parse signature: %v", err)
+		}
+
+		derSig2, err := sig2.ToSignature()
+		if err != nil {
+			t.Fatalf("failed to reconvert signature to DER: %v",
+				err)
+		}
+
+		derBytes := derSig.Serialize()
+		derBytes2 := derSig2.Serialize()
+		if !bytes.Equal(derBytes, derBytes2) {
+			t.Fatalf("signature mismatch: %v != %v", derBytes,
+				derBytes2)
+		}
+	})
+}