1/*
2Copyright 2014 The Kubernetes Authors.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8    http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17package versioning
18
19import (
20	"io"
21	"reflect"
22
23	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
24	"k8s.io/apimachinery/pkg/runtime"
25	"k8s.io/apimachinery/pkg/runtime/schema"
26)
27
28// NewDefaultingCodecForScheme is a convenience method for callers that are using a scheme.
29func NewDefaultingCodecForScheme(
30	// TODO: I should be a scheme interface?
31	scheme *runtime.Scheme,
32	encoder runtime.Encoder,
33	decoder runtime.Decoder,
34	encodeVersion runtime.GroupVersioner,
35	decodeVersion runtime.GroupVersioner,
36) runtime.Codec {
37	return NewCodec(encoder, decoder, runtime.UnsafeObjectConvertor(scheme), scheme, scheme, scheme, encodeVersion, decodeVersion, scheme.Name())
38}
39
40// NewCodec takes objects in their internal versions and converts them to external versions before
41// serializing them. It assumes the serializer provided to it only deals with external versions.
42// This class is also a serializer, but is generally used with a specific version.
43func NewCodec(
44	encoder runtime.Encoder,
45	decoder runtime.Decoder,
46	convertor runtime.ObjectConvertor,
47	creater runtime.ObjectCreater,
48	typer runtime.ObjectTyper,
49	defaulter runtime.ObjectDefaulter,
50	encodeVersion runtime.GroupVersioner,
51	decodeVersion runtime.GroupVersioner,
52	originalSchemeName string,
53) runtime.Codec {
54	internal := &codec{
55		encoder:   encoder,
56		decoder:   decoder,
57		convertor: convertor,
58		creater:   creater,
59		typer:     typer,
60		defaulter: defaulter,
61
62		encodeVersion: encodeVersion,
63		decodeVersion: decodeVersion,
64
65		originalSchemeName: originalSchemeName,
66	}
67	return internal
68}
69
70type codec struct {
71	encoder   runtime.Encoder
72	decoder   runtime.Decoder
73	convertor runtime.ObjectConvertor
74	creater   runtime.ObjectCreater
75	typer     runtime.ObjectTyper
76	defaulter runtime.ObjectDefaulter
77
78	encodeVersion runtime.GroupVersioner
79	decodeVersion runtime.GroupVersioner
80
81	// originalSchemeName is optional, but when filled in it holds the name of the scheme from which this codec originates
82	originalSchemeName string
83}
84
85// Decode attempts a decode of the object, then tries to convert it to the internal version. If into is provided and the decoding is
86// successful, the returned runtime.Object will be the value passed as into. Note that this may bypass conversion if you pass an
87// into that matches the serialized version.
88func (c *codec) Decode(data []byte, defaultGVK *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) {
89	versioned, isVersioned := into.(*runtime.VersionedObjects)
90	if isVersioned {
91		into = versioned.Last()
92	}
93
94	// If the into object is unstructured and expresses an opinion about its group/version,
95	// create a new instance of the type so we always exercise the conversion path (skips short-circuiting on `into == obj`)
96	decodeInto := into
97	if into != nil {
98		if _, ok := into.(runtime.Unstructured); ok && !into.GetObjectKind().GroupVersionKind().GroupVersion().Empty() {
99			decodeInto = reflect.New(reflect.TypeOf(into).Elem()).Interface().(runtime.Object)
100		}
101	}
102
103	obj, gvk, err := c.decoder.Decode(data, defaultGVK, decodeInto)
104	if err != nil {
105		return nil, gvk, err
106	}
107
108	if d, ok := obj.(runtime.NestedObjectDecoder); ok {
109		if err := d.DecodeNestedObjects(runtime.WithoutVersionDecoder{c.decoder}); err != nil {
110			return nil, gvk, err
111		}
112	}
113
114	// if we specify a target, use generic conversion.
115	if into != nil {
116		// perform defaulting if requested
117		if c.defaulter != nil {
118			// create a copy to ensure defaulting is not applied to the original versioned objects
119			if isVersioned {
120				versioned.Objects = []runtime.Object{obj.DeepCopyObject()}
121			}
122			c.defaulter.Default(obj)
123		} else {
124			if isVersioned {
125				versioned.Objects = []runtime.Object{obj}
126			}
127		}
128
129		// Short-circuit conversion if the into object is same object
130		if into == obj {
131			if isVersioned {
132				return versioned, gvk, nil
133			}
134			return into, gvk, nil
135		}
136
137		if err := c.convertor.Convert(obj, into, c.decodeVersion); err != nil {
138			return nil, gvk, err
139		}
140
141		if isVersioned {
142			versioned.Objects = append(versioned.Objects, into)
143			return versioned, gvk, nil
144		}
145		return into, gvk, nil
146	}
147
148	// Convert if needed.
149	if isVersioned {
150		// create a copy, because ConvertToVersion does not guarantee non-mutation of objects
151		versioned.Objects = []runtime.Object{obj.DeepCopyObject()}
152	}
153
154	// perform defaulting if requested
155	if c.defaulter != nil {
156		c.defaulter.Default(obj)
157	}
158
159	out, err := c.convertor.ConvertToVersion(obj, c.decodeVersion)
160	if err != nil {
161		return nil, gvk, err
162	}
163	if isVersioned {
164		if versioned.Last() != out {
165			versioned.Objects = append(versioned.Objects, out)
166		}
167		return versioned, gvk, nil
168	}
169	return out, gvk, nil
170}
171
172// Encode ensures the provided object is output in the appropriate group and version, invoking
173// conversion if necessary. Unversioned objects (according to the ObjectTyper) are output as is.
174func (c *codec) Encode(obj runtime.Object, w io.Writer) error {
175	switch obj := obj.(type) {
176	case *runtime.Unknown:
177		return c.encoder.Encode(obj, w)
178	case runtime.Unstructured:
179		// An unstructured list can contain objects of multiple group version kinds. don't short-circuit just
180		// because the top-level type matches our desired destination type. actually send the object to the converter
181		// to give it a chance to convert the list items if needed.
182		if _, ok := obj.(*unstructured.UnstructuredList); !ok {
183			// avoid conversion roundtrip if GVK is the right one already or is empty (yes, this is a hack, but the old behaviour we rely on in kubectl)
184			objGVK := obj.GetObjectKind().GroupVersionKind()
185			if len(objGVK.Version) == 0 {
186				return c.encoder.Encode(obj, w)
187			}
188			targetGVK, ok := c.encodeVersion.KindForGroupVersionKinds([]schema.GroupVersionKind{objGVK})
189			if !ok {
190				return runtime.NewNotRegisteredGVKErrForTarget(c.originalSchemeName, objGVK, c.encodeVersion)
191			}
192			if targetGVK == objGVK {
193				return c.encoder.Encode(obj, w)
194			}
195		}
196	}
197
198	gvks, isUnversioned, err := c.typer.ObjectKinds(obj)
199	if err != nil {
200		return err
201	}
202
203	objectKind := obj.GetObjectKind()
204	old := objectKind.GroupVersionKind()
205	// restore the old GVK after encoding
206	defer objectKind.SetGroupVersionKind(old)
207
208	if c.encodeVersion == nil || isUnversioned {
209		if e, ok := obj.(runtime.NestedObjectEncoder); ok {
210			if err := e.EncodeNestedObjects(runtime.WithVersionEncoder{Encoder: c.encoder, ObjectTyper: c.typer}); err != nil {
211				return err
212			}
213		}
214		objectKind.SetGroupVersionKind(gvks[0])
215		return c.encoder.Encode(obj, w)
216	}
217
218	// Perform a conversion if necessary
219	out, err := c.convertor.ConvertToVersion(obj, c.encodeVersion)
220	if err != nil {
221		return err
222	}
223
224	if e, ok := out.(runtime.NestedObjectEncoder); ok {
225		if err := e.EncodeNestedObjects(runtime.WithVersionEncoder{Version: c.encodeVersion, Encoder: c.encoder, ObjectTyper: c.typer}); err != nil {
226			return err
227		}
228	}
229
230	// Conversion is responsible for setting the proper group, version, and kind onto the outgoing object
231	return c.encoder.Encode(out, w)
232}
233