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| 1 | +/* |
| 2 | +Copyright 2021 The Knative Authors |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +package json |
| 18 | + |
| 19 | +import ( |
| 20 | + "bytes" |
| 21 | + "encoding/json" |
| 22 | + "io" |
| 23 | +) |
| 24 | + |
| 25 | +var ( |
| 26 | + emptyMeta = []byte(`:{}`) |
| 27 | + metaPrefix = []byte(`{"metadata"`) |
| 28 | + metaSuffix = []byte(`}`) |
| 29 | +) |
| 30 | + |
| 31 | +var ( |
| 32 | + // Unmarshal is an alias for json.Unmarshal |
| 33 | + Unmarshal = json.Unmarshal |
| 34 | + |
| 35 | + //Marshal is an alias for json.Marshal |
| 36 | + Marshal = json.Marshal |
| 37 | +) |
| 38 | + |
| 39 | +// Decode will parse the json byte array to the target object. When |
| 40 | +// unknown fields are _not_ allowed we still accept unknown |
| 41 | +// fields in the Object's metadata |
| 42 | +// |
| 43 | +// See https://github.com/knative/serving/issues/11448 for details |
| 44 | +func Decode(bites []byte, target interface{}, disallowUnknownFields bool) error { |
| 45 | + if !disallowUnknownFields { |
| 46 | + return json.Unmarshal(bites, target) |
| 47 | + } |
| 48 | + |
| 49 | + // If we don't allow unknown fields we skip validating fields in the metadata |
| 50 | + // block since that is opaque to us and validated by the API server |
| 51 | + start, end, err := findMetadataOffsets(bites) |
| 52 | + if err != nil { |
| 53 | + return err |
| 54 | + } else if start == -1 || end == -1 { |
| 55 | + // If for some reason the json does not have metadata continue with normal parsing |
| 56 | + dec := json.NewDecoder(bytes.NewReader(bites)) |
| 57 | + dec.DisallowUnknownFields() |
| 58 | + return dec.Decode(target) |
| 59 | + } |
| 60 | + |
| 61 | + before := bites[:start] |
| 62 | + metadata := bites[start:end] |
| 63 | + after := bites[end:] |
| 64 | + |
| 65 | + // Parse everything but skip metadata |
| 66 | + dec := json.NewDecoder(io.MultiReader( |
| 67 | + bytes.NewReader(before), |
| 68 | + bytes.NewReader(emptyMeta), |
| 69 | + bytes.NewReader(after), |
| 70 | + )) |
| 71 | + |
| 72 | + dec.DisallowUnknownFields() |
| 73 | + if err := dec.Decode(target); err != nil { |
| 74 | + return err |
| 75 | + } |
| 76 | + |
| 77 | + // Now we parse just the metadata |
| 78 | + dec = json.NewDecoder(io.MultiReader( |
| 79 | + bytes.NewReader(metaPrefix), |
| 80 | + bytes.NewReader(metadata), |
| 81 | + bytes.NewReader(metaSuffix), |
| 82 | + )) |
| 83 | + |
| 84 | + if err := dec.Decode(target); err != nil { |
| 85 | + return err |
| 86 | + } |
| 87 | + |
| 88 | + return nil |
| 89 | +} |
| 90 | + |
| 91 | +func findMetadataOffsets(bites []byte) (start, end int64, err error) { |
| 92 | + start, end = -1, -1 |
| 93 | + level := 0 |
| 94 | + |
| 95 | + var ( |
| 96 | + dec = json.NewDecoder(bytes.NewReader(bites)) |
| 97 | + t json.Token |
| 98 | + ) |
| 99 | + |
| 100 | + for { |
| 101 | + t, err = dec.Token() |
| 102 | + if err == io.EOF { //nolint |
| 103 | + break |
| 104 | + } |
| 105 | + if err != nil { |
| 106 | + return |
| 107 | + } |
| 108 | + |
| 109 | + switch v := t.(type) { |
| 110 | + case json.Delim: |
| 111 | + if v == '{' { |
| 112 | + level++ |
| 113 | + } else if v == '}' { |
| 114 | + level-- |
| 115 | + } |
| 116 | + case string: |
| 117 | + if v == "metadata" && level == 1 { |
| 118 | + start = dec.InputOffset() |
| 119 | + x := struct{}{} |
| 120 | + if err = dec.Decode(&x); err != nil { |
| 121 | + return -1, -1, err |
| 122 | + } |
| 123 | + end = dec.InputOffset() |
| 124 | + |
| 125 | + // we exit early to stop processing the rest of the object |
| 126 | + return |
| 127 | + } |
| 128 | + } |
| 129 | + } |
| 130 | + return -1, -1, nil |
| 131 | +} |
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