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encoding/json: disallow unknown fields in Decoder
Add a DisallowUnknownFields flag to Decoder. DisallowUnknownFields causes the Decoder to return an error when the the decoding destination is a struct and the input contains object keys which do not match any non-ignored, public field the destination, including keys whose value is set to null. Note: this fix has already been worked on in 27231, which seems to be abandoned. This version is a slightly simpler implementation and is up to date with the master branch. Fixes #15314 Change-Id: I987a5857c52018df334f4d1a2360649c44a7175d Reviewed-on: https://go-review.googlesource.com/74830 Reviewed-by: Joe Tsai <joetsai@google.com> Run-TryBot: Joe Tsai <joetsai@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Ivan Bertona
Joe Tsai
parent
d58f4e9b7b
commit
2596a0c075
@ -44,8 +44,9 @@ import (
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//
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// To unmarshal JSON into a struct, Unmarshal matches incoming object
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// keys to the keys used by Marshal (either the struct field name or its tag),
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// preferring an exact match but also accepting a case-insensitive match.
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// Unmarshal will only set exported fields of the struct.
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// preferring an exact match but also accepting a case-insensitive match. By
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// default, object keys which don't have a corresponding struct field are
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// ignored (see Decoder.DisallowUnknownFields for an alternative).
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//
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// To unmarshal JSON into an interface value,
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// Unmarshal stores one of these in the interface value:
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@ -277,6 +278,7 @@ type decodeState struct {
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}
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savedError error
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useNumber bool
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disallowUnknownFields bool
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}
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// errPhase is used for errors that should not happen unless
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@ -713,6 +715,8 @@ func (d *decodeState) object(v reflect.Value) {
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}
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d.errorContext.Field = f.name
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d.errorContext.Struct = v.Type().Name()
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} else if d.disallowUnknownFields {
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d.saveError(fmt.Errorf("json: unknown field %q", key))
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}
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}
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@ -378,6 +378,7 @@ type unmarshalTest struct {
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err error
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useNumber bool
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golden bool
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disallowUnknownFields bool
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}
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type B struct {
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@ -401,6 +402,7 @@ var unmarshalTests = []unmarshalTest{
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{in: "null", ptr: new(interface{}), out: nil},
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{in: `{"X": [1,2,3], "Y": 4}`, ptr: new(T), out: T{Y: 4}, err: &UnmarshalTypeError{"array", reflect.TypeOf(""), 7, "T", "X"}},
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{in: `{"x": 1}`, ptr: new(tx), out: tx{}},
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{in: `{"x": 1}`, ptr: new(tx), err: fmt.Errorf("json: unknown field \"x\""), disallowUnknownFields: true},
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{in: `{"F1":1,"F2":2,"F3":3}`, ptr: new(V), out: V{F1: float64(1), F2: int32(2), F3: Number("3")}},
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{in: `{"F1":1,"F2":2,"F3":3}`, ptr: new(V), out: V{F1: Number("1"), F2: int32(2), F3: Number("3")}, useNumber: true},
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{in: `{"k1":1,"k2":"s","k3":[1,2.0,3e-3],"k4":{"kk1":"s","kk2":2}}`, ptr: new(interface{}), out: ifaceNumAsFloat64},
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@ -415,10 +417,13 @@ var unmarshalTests = []unmarshalTest{
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// Z has a "-" tag.
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{in: `{"Y": 1, "Z": 2}`, ptr: new(T), out: T{Y: 1}},
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{in: `{"Y": 1, "Z": 2}`, ptr: new(T), err: fmt.Errorf("json: unknown field \"Z\""), disallowUnknownFields: true},
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{in: `{"alpha": "abc", "alphabet": "xyz"}`, ptr: new(U), out: U{Alphabet: "abc"}},
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{in: `{"alpha": "abc", "alphabet": "xyz"}`, ptr: new(U), err: fmt.Errorf("json: unknown field \"alphabet\""), disallowUnknownFields: true},
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{in: `{"alpha": "abc"}`, ptr: new(U), out: U{Alphabet: "abc"}},
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{in: `{"alphabet": "xyz"}`, ptr: new(U), out: U{}},
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{in: `{"alphabet": "xyz"}`, ptr: new(U), err: fmt.Errorf("json: unknown field \"alphabet\""), disallowUnknownFields: true},
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// syntax errors
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{in: `{"X": "foo", "Y"}`, err: &SyntaxError{"invalid character '}' after object key", 17}},
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@ -609,11 +614,23 @@ var unmarshalTests = []unmarshalTest{
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ptr: new(S5),
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out: S5{S8: S8{S9: S9{Y: 2}}},
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},
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{
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in: `{"X": 1,"Y":2}`,
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ptr: new(S5),
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err: fmt.Errorf("json: unknown field \"X\""),
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disallowUnknownFields: true,
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},
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{
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in: `{"X": 1,"Y":2}`,
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ptr: new(S10),
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out: S10{S13: S13{S8: S8{S9: S9{Y: 2}}}},
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},
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{
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in: `{"X": 1,"Y":2}`,
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ptr: new(S10),
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err: fmt.Errorf("json: unknown field \"X\""),
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disallowUnknownFields: true,
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},
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// invalid UTF-8 is coerced to valid UTF-8.
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{
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@ -793,6 +810,62 @@ var unmarshalTests = []unmarshalTest{
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{in: `{"B": "False"}`, ptr: new(B), err: errors.New(`json: invalid use of ,string struct tag, trying to unmarshal "False" into bool`)},
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{in: `{"B": "null"}`, ptr: new(B), out: B{false}},
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{in: `{"B": "nul"}`, ptr: new(B), err: errors.New(`json: invalid use of ,string struct tag, trying to unmarshal "nul" into bool`)},
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// additional tests for disallowUnknownFields
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{
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in: `{
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"Level0": 1,
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"Level1b": 2,
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"Level1c": 3,
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"x": 4,
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"Level1a": 5,
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"LEVEL1B": 6,
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"e": {
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"Level1a": 8,
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"Level1b": 9,
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"Level1c": 10,
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"Level1d": 11,
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"x": 12
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},
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"Loop1": 13,
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"Loop2": 14,
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"X": 15,
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"Y": 16,
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"Z": 17,
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"Q": 18,
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"extra": true
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}`,
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ptr: new(Top),
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err: fmt.Errorf("json: unknown field \"extra\""),
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disallowUnknownFields: true,
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},
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{
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in: `{
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"Level0": 1,
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"Level1b": 2,
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"Level1c": 3,
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"x": 4,
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"Level1a": 5,
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"LEVEL1B": 6,
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"e": {
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"Level1a": 8,
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"Level1b": 9,
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"Level1c": 10,
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"Level1d": 11,
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"x": 12,
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"extra": null
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},
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"Loop1": 13,
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"Loop2": 14,
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"X": 15,
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"Y": 16,
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"Z": 17,
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"Q": 18
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}`,
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ptr: new(Top),
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err: fmt.Errorf("json: unknown field \"extra\""),
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disallowUnknownFields: true,
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},
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}
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func TestMarshal(t *testing.T) {
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@ -911,6 +984,9 @@ func TestUnmarshal(t *testing.T) {
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if tt.useNumber {
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dec.UseNumber()
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}
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if tt.disallowUnknownFields {
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dec.DisallowUnknownFields()
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}
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if err := dec.Decode(v.Interface()); !reflect.DeepEqual(err, tt.err) {
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t.Errorf("#%d: %v, want %v", i, err, tt.err)
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continue
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@ -35,6 +35,11 @@ func NewDecoder(r io.Reader) *Decoder {
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// Number instead of as a float64.
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func (dec *Decoder) UseNumber() { dec.d.useNumber = true }
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// DisallowUnknownFields causes the Decoder to return an error when the destination
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// is a struct and the input contains object keys which do not match any
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// non-ignored, exported fields in the destination.
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func (dec *Decoder) DisallowUnknownFields() { dec.d.disallowUnknownFields = true }
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// Decode reads the next JSON-encoded value from its
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// input and stores it in the value pointed to by v.
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//
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