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Add decoding option for return type of data with an unknown tag
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Adds a decoding option to specify the preferred return type when unmarshalling a data with an unknown tag.
If this option is not set, Unmarshal returns a value of type Tag{}. This ensures backward compatibility.
If the option is set, Unmarshal returns the unmarshalled content.

Signed-off-by: Suriyan Subbarayan suriyansub710@gmail.com
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@ssuriyan7
ssuriyan7 committed Feb 3, 2024
1 parent 25223c7 commit 2c841f6
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Showing 2 changed files with 219 additions and 0 deletions.
33 changes: 33 additions & 0 deletions decode.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -446,6 +446,26 @@ func (fnbsm FieldNameByteStringMode) valid() bool {
return fnbsm >= 0 && fnbsm < maxFieldNameByteStringMode
}

// UnrecognizedTagToAnyMode specifies how to decode unrecognized CBOR tag into an empty interface (any).
// Currently, recognized CBOR tag numbers are 0, 1, 2, 3, or registered by TagSet.
type UnrecognizedTagToAnyMode int

const (
// UnrecognizedTagNumAndContentToAny decodes CBOR tag number and tag content to cbor.Tag
// when decoding unrecognized CBOR tag into an empty interface.
UnrecognizedTagNumAndContentToAny UnrecognizedTagToAnyMode = iota

// UnrecognizedTagContentToAny decodes only CBOR tag content (into its default type)
// when decoding unrecognized CBOR tag into an empty interface.
UnrecognizedTagContentToAny

maxUnrecognizedTagToAny
)

func (uttam UnrecognizedTagToAnyMode) valid() bool {
return uttam >= 0 && uttam < maxUnrecognizedTagToAny
}

// DecOptions specifies decoding options.
type DecOptions struct {
// DupMapKey specifies whether to enforce duplicate map key.
Expand Down Expand Up @@ -514,6 +534,10 @@ type DecOptions struct {
// FieldNameByteString specifies the behavior when decoding a CBOR byte string map key as a
// Go struct field name.
FieldNameByteString FieldNameByteStringMode

// UnrecognizedTagToAny specifies how to decode unrecognized CBOR tag into an empty interface.
// Currently, recognized CBOR tag numbers are 0, 1, 2, 3, or registered by TagSet.
UnrecognizedTagToAny UnrecognizedTagToAnyMode
}

// DecMode returns DecMode with immutable options and no tags (safe for concurrency).
Expand Down Expand Up @@ -637,6 +661,9 @@ func (opts DecOptions) decMode() (*decMode, error) {
if !opts.FieldNameByteString.valid() {
return nil, errors.New("cbor: invalid FieldNameByteString " + strconv.Itoa(int(opts.FieldNameByteString)))
}
if !opts.UnrecognizedTagToAny.valid() {
return nil, errors.New("cbor: invalid UnrecognizedTagToAnyMode " + strconv.Itoa(int(opts.UnrecognizedTagToAny)))
}
dm := decMode{
dupMapKey: opts.DupMapKey,
timeTag: opts.TimeTag,
Expand All @@ -655,6 +682,7 @@ func (opts DecOptions) decMode() (*decMode, error) {
defaultByteStringType: opts.DefaultByteStringType,
byteStringToString: opts.ByteStringToString,
fieldNameByteString: opts.FieldNameByteString,
unrecognizedTagToAny: opts.UnrecognizedTagToAny,
}
return &dm, nil
}
Expand Down Expand Up @@ -724,6 +752,7 @@ type decMode struct {
defaultByteStringType reflect.Type
byteStringToString ByteStringToStringMode
fieldNameByteString FieldNameByteStringMode
unrecognizedTagToAny UnrecognizedTagToAnyMode
}

var defaultDecMode, _ = DecOptions{}.decMode()
Expand All @@ -747,6 +776,7 @@ func (dm *decMode) DecOptions() DecOptions {
DefaultByteStringType: dm.defaultByteStringType,
ByteStringToString: dm.byteStringToString,
FieldNameByteString: dm.fieldNameByteString,
UnrecognizedTagToAny: dm.unrecognizedTagToAny,
}
}

Expand Down Expand Up @@ -1426,6 +1456,9 @@ func (d *decoder) parse(skipSelfDescribedTag bool) (interface{}, error) { //noli
if err != nil {
return nil, err
}
if d.dm.unrecognizedTagToAny == UnrecognizedTagContentToAny {
return content, nil
}
return Tag{tagNum, content}, nil
case cborTypePrimitives:
_, ai, val := d.getHead()
Expand Down
186 changes: 186 additions & 0 deletions decode_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8366,6 +8366,192 @@ func TestUnmarshalFieldNameByteString(t *testing.T) {
}
}

func TestDecModeInvalidReturnTypeForEmptyInterface(t *testing.T) {
for _, tc := range []struct {
name string
opts DecOptions
wantErrorMsg string
}{
{
name: "below range of valid modes",
opts: DecOptions{UnrecognizedTagToAny: -1},
wantErrorMsg: "cbor: invalid UnrecognizedTagToAnyMode -1",
},
{
name: "above range of valid modes",
opts: DecOptions{UnrecognizedTagToAny: 101},
wantErrorMsg: "cbor: invalid UnrecognizedTagToAnyMode 101",
},
} {
t.Run(tc.name, func(t *testing.T) {
_, err := tc.opts.DecMode()
if err == nil {
t.Errorf("DecMode() didn't return an error")
} else if err.Error() != tc.wantErrorMsg {
t.Errorf("DecMode() returned error %q, want %q", err.Error(), tc.wantErrorMsg)
}
})
}
}

func TestUnmarshalWithUnrecognizedTagToAnyMode(t *testing.T) {
for _, tc := range []struct {
name string
opts DecOptions
in []byte
want interface{}
}{
{
name: "default to value of type Tag",
opts: DecOptions{},
in: hexDecode("d8ff00"),
want: Tag{Number: uint64(255), Content: uint64(0)},
},
{
name: "Tag's content",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("d8ff00"),
want: uint64(0),
},
} {
t.Run(tc.name, func(t *testing.T) {
dm, err := tc.opts.DecMode()
if err != nil {
t.Fatal(err)
}

var got interface{}
if err := dm.Unmarshal(tc.in, &got); err != nil {
t.Errorf("unexpected error: %v", err)
}

if tc.want != got {
t.Errorf("got %s, want %s", got, tc.want)
}
})
}
}

func TestUnmarshalWithUnrecognizedTagToAnyModeForSupportedTags(t *testing.T) {
for _, tc := range []struct {
name string
opts DecOptions
in []byte
want interface{}
}{
{
name: "Unmarshal with tag number 0 when UnrecognizedTagContentToAny option is not set",
opts: DecOptions{},
in: hexDecode("c074323031332d30332d32315432303a30343a30305a"),
want: time.Date(2013, 3, 21, 20, 4, 0, 0, time.UTC),
},
{
name: "Unmarshal with tag number 0 when UnrecognizedTagContentToAny option is set",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("c074323031332d30332d32315432303a30343a30305a"),
want: time.Date(2013, 3, 21, 20, 4, 0, 0, time.UTC),
},
{
name: "Unmarshal with tag number 1 when UnrecognizedTagContentToAny option is not set",
opts: DecOptions{},
in: hexDecode("c11a514b67b0"),
want: time.Date(2013, 3, 21, 20, 4, 0, 0, time.UTC),
},
{
name: "Unmarshal with tag number 1 when UnrecognizedTagContentToAny option is set",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("c11a514b67b0"),
want: time.Date(2013, 3, 21, 20, 4, 0, 0, time.UTC),
},
{
name: "Unmarshal with tag number 2 when UnrecognizedTagContentToAny option is not set",
opts: DecOptions{},
in: hexDecode("c249010000000000000000"),
want: bigIntOrPanic("18446744073709551616"),
},
{
name: "Unmarshal with tag number 2 when UnrecognizedTagContentToAny option is set",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("c249010000000000000000"),
want: bigIntOrPanic("18446744073709551616"),
},
{
name: "Unmarshal with tag number 3 when UnrecognizedTagContentToAny option is not set",
opts: DecOptions{},
in: hexDecode("c349010000000000000000"),
want: bigIntOrPanic("-18446744073709551617"),
},
{
name: "Unmarshal with tag number 3 when UnrecognizedTagContentToAny option is set",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("c349010000000000000000"),
want: bigIntOrPanic("-18446744073709551617"),
},
} {
t.Run(tc.name, func(t *testing.T) {
dm, err := tc.opts.DecMode()
if err != nil {
t.Fatal(err)
}

var got interface{}
if err := dm.Unmarshal(tc.in, &got); err != nil {
t.Errorf("unexpected error: %v", err)
}

compareNonFloats(t, tc.in, got, tc.want)

})
}
}

func TestUnmarshalWithUnrecognizedTagToAnyModeForSharedTag(t *testing.T) {

type myInt int
typ := reflect.TypeOf(myInt(0))

tags := NewTagSet()
if err := tags.Add(TagOptions{EncTag: EncTagRequired, DecTag: DecTagRequired}, typ, 125); err != nil {
t.Fatalf("TagSet.Add(%s, %v) returned error %v", typ, 125, err)
}

for _, tc := range []struct {
name string
opts DecOptions
in []byte
want interface{}
}{
{
name: "Unmarshal with a shared tag when UnrecognizedTagContentToAny option is not set",
opts: DecOptions{},
in: hexDecode("d9d9f7d87d01"), // 55799(125(1))
want: myInt(1),
},
{
name: "Unmarshal with a shared tag when UnrecognizedTagContentToAny option is set",
opts: DecOptions{UnrecognizedTagToAny: UnrecognizedTagContentToAny},
in: hexDecode("d9d9f7d87d01"), // 55799(125(1))
want: myInt(1),
},
} {
t.Run(tc.name, func(t *testing.T) {
dm, err := tc.opts.DecModeWithTags(tags)
if err != nil {
t.Fatal(err)
}

var got interface{}

if err := dm.Unmarshal(tc.in, &got); err != nil {
t.Errorf("unexpected error: %v", err)
}

compareNonFloats(t, tc.in, got, tc.want)

})
}
}

func isCBORNil(data []byte) bool {
return len(data) > 0 && (data[0] == 0xf6 || data[0] == 0xf7)
}

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