encoding/asn1: fix unmarshalling SEQUENCE OF SET

Fixes #27426

Change-Id: I34d4784658ce7b9e6130bae9717e80d0e9a290a2
GitHub-Last-Rev: 6de610cdce
GitHub-Pull-Request: golang/go#30059
Reviewed-on: https://go-review.googlesource.com/c/go/+/160819
Reviewed-by: Agniva De Sarker <agniva.quicksilver@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>

src/encoding/asn1/asn1_test.go

@@ -1129,3 +1129,22 @@ func TestBMPString(t *testing.T) {
 		}
 	}
 }
+
+func TestSequenceOfSet(t *testing.T) {
+	type someSetSET struct {
+		A int `asn1:"tag:0"`
+	}
+
+	type someStruct struct {
+		B int          `asn1:"tag:0"`
+		C []someSetSET `asn1:"tag:1"`
+	}
+
+	der := []byte{0x30, 0x0F, 0x80, 0x01, 0x01, 0xA1, 0x0A, 0x31, 0x03, 0x80, 0x01, 0x01, 0x31, 0x03, 0x80, 0x01, 0x02}
+
+	var b someStruct
+	if _, err := Unmarshal(der, &b); err != nil {
+		t.Errorf("Unmarshal failed: %v", err)
+	}
+
+}

src/encoding/asn1/common.go

@@ -167,6 +167,9 @@ func getUniversalType(t reflect.Type) (matchAny bool, tagNumber int, isCompound,
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		return false, TagInteger, false, true
 	case reflect.Struct:
+		if strings.HasSuffix(t.Name(), "SET") {
+			return false, TagSet, true, true
+		}
 		return false, TagSequence, true, true
 	case reflect.Slice:
 		if t.Elem().Kind() == reflect.Uint8 {