Address review feedback

Change-Id: Ib6a8fb2f9b20dbff5f24b18cc5a217d95066a98f

src/encoding/asn1/marshal.go

@@ -80,26 +80,6 @@ func (m multiEncoder) Encode(dst []byte) {
 	}
 }
 
-type octetSorter [][]byte
-
-func (s octetSorter) Len() int {
-	return len(s)
-}
-
-func (s octetSorter) Swap(i, j int) {
-	s[i], s[j] = s[j], s[i]
-}
-
-func (s octetSorter) Less(i, j int) bool {
-	// Since we are using bytes.Compare to compare TLV encodings we
-	// don't need to right pad s[i] and s[j] to the same length as
-	// suggested in X690. If len(s[i]) < len(s[j]) the length octet of
-	// s[i], which is the first determining byte, will inherently be
-	// smaller than the length octet of s[j]. This lets us skip the
-	// padding step.
-	return bytes.Compare(s[i], s[j]) < 0
-}
-
 type setEncoder []encoder
 
 func (s setEncoder) Len() int {
@@ -125,7 +105,15 @@ func (s setEncoder) Encode(dst []byte) {
 		e.Encode(l[i])
 	}
 
-	sort.Sort(octetSorter(l))
+	sort.Slice(l, func(i, j int) bool {
+		// Since we are using bytes.Compare to compare TLV encodings we
+		// don't need to right pad s[i] and s[j] to the same length as
+		// suggested in X690. If len(s[i]) < len(s[j]) the length octet of
+		// s[i], which is the first determining byte, will inherently be
+		// smaller than the length octet of s[j]. This lets us skip the
+		// padding step.
+		return bytes.Compare(l[i], l[j]) < 0
+	})
 
 	var off int
 	for _, b := range l {
@@ -677,6 +665,15 @@ func makeField(v reflect.Value, params fieldParameters) (e encoder, err error) {
 		tag = TagSet
 	}
 
+	// makeField can be called for a slice that should be treated as a SET
+	// but doesn't have params.set set, for instance when using a slice
+	// with the SET type name suffix. In this case getUniversalType returns
+	// TagSet, but makeBody doesn't know about that so will treat the slice
+	// as a sequence. To work around this we set params.set.
+	if tag == TagSet && !params.set {
+		params.set = true
+	}
+
 	t := new(taggedEncoder)
 
 	t.body, err = makeBody(v, params)

src/encoding/asn1/marshal_test.go

@@ -347,6 +347,32 @@ func TestSetEncoder(t *testing.T) {
 		t.Error("Unmarshal returned extra garbage")
 	}
 	if !reflect.DeepEqual(expectedOrder, resultStruct.Strings) {
-		t.Errorf("Unexpected SET content. got: %s, want: %s", resultStruct.Strings, resultStruct.Strings)
+		t.Errorf("Unexpected SET content. got: %s, want: %s", resultStruct.Strings, expectedOrder)
+	}
+}
+
+func TestSetEncoderSETSliceSuffix(t *testing.T) {
+	type testSetSET []string
+	testSet := testSetSET{"a", "aa", "b", "bb", "c", "cc"}
+
+	// Expected ordering of the SET should be:
+	// a, b, c, aa, bb, cc
+
+	output, err := Marshal(testSet)
+	if err != nil {
+		t.Errorf("%v", err)
+	}
+
+	expectedOrder := testSetSET{"a", "b", "c", "aa", "bb", "cc"}
+	var resultSet testSetSET
+	rest, err := Unmarshal(output, &resultSet)
+	if err != nil {
+		t.Errorf("%v", err)
+	}
+	if len(rest) != 0 {
+		t.Error("Unmarshal returned extra garbage")
+	}
+	if !reflect.DeepEqual(expectedOrder, resultSet) {
+		t.Errorf("Unexpected SET content. got: %s, want: %s", resultSet, expectedOrder)
 	}
 }