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sizeCheckUnmarshalizer.go
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/
sizeCheckUnmarshalizer.go
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package marshal
var _ Marshalizer = (*sizeCheckUnmarshalizer)(nil)
type sizeCheckUnmarshalizer struct {
Marshalizer
acceptedDelta uint32
}
// NewSizeCheckUnmarshalizer creates a wrapper around an existing marshalizer m
// which, during unmarshaling, also checks that the provided buffer dose not contain
// additional unused data.
func NewSizeCheckUnmarshalizer(m Marshalizer, maxDelta uint32) Marshalizer {
scu := &sizeCheckUnmarshalizer{
Marshalizer: m,
acceptedDelta: maxDelta,
}
return scu
}
// Unmarshal tries to unmarshal input buffer values into output object, and checks
// for additional unused data
func (scu *sizeCheckUnmarshalizer) Unmarshal(obj interface{}, buff []byte) error {
err := scu.Marshalizer.Unmarshal(obj, buff)
if err != nil {
return err
}
var objSize int
result, ok := obj.(Sizer)
if !ok {
out, errMarshal := scu.Marshal(obj)
if errMarshal != nil {
return errMarshal
}
objSize = len(out)
} else {
objSize = result.Size()
}
maxSize := objSize + objSize*int(scu.acceptedDelta)/100
if len(buff) > maxSize {
return ErrUnmarshallingBadSize
}
return nil
}
// IsInterfaceNil returns true if there is no value under the interface or
// target marshalizer
func (scu *sizeCheckUnmarshalizer) IsInterfaceNil() bool {
if scu != nil {
return scu.Marshalizer == nil || scu.Marshalizer.IsInterfaceNil()
}
return true
}