vendor/github.com/jcmturner/rpc/v2/ndr/decoder.go - voltha-go - Gitiles

 // Package ndr provides the ability to unmarshal NDR encoded byte steams into Go data structures
 package ndr

 import (
 	"bufio"
 	"fmt"
 	"io"
 	"reflect"
 	"strings"
 )

 // Struct tag values
 const (
 	TagConformant = "conformant"
 	TagVarying    = "varying"
 	TagPointer    = "pointer"
 	TagPipe       = "pipe"
 )

 // Decoder unmarshals NDR byte stream data into a Go struct representation
 type Decoder struct {
 	r             *bufio.Reader // source of the data
 	size          int           // initial size of bytes in buffer
 	ch            CommonHeader  // NDR common header
 	ph            PrivateHeader // NDR private header
 	conformantMax []uint32      // conformant max values that were moved to the beginning of the structure
 	s             interface{}   // pointer to the structure being populated
 	current       []string      // keeps track of the current field being populated
 }

 type deferedPtr struct {
 	v   reflect.Value
 	tag reflect.StructTag
 }

 // NewDecoder creates a new instance of a NDR Decoder.
 func NewDecoder(r io.Reader) *Decoder {
 	dec := new(Decoder)
 	dec.r = bufio.NewReader(r)
 	dec.r.Peek(int(commonHeaderBytes)) // For some reason an operation is needed on the buffer to initialise it so Buffered() != 0
 	dec.size = dec.r.Buffered()
 	return dec
 }

 // Decode unmarshals the NDR encoded bytes into the pointer of a struct provided.
 func (dec *Decoder) Decode(s interface{}) error {
 	dec.s = s
 	err := dec.readCommonHeader()
 	if err != nil {
 		return err
 	}
 	err = dec.readPrivateHeader()
 	if err != nil {
 		return err
 	}
 	_, err = dec.r.Discard(4) //The next 4 bytes are an RPC unique pointer referent. We just skip these.
 	if err != nil {
 		return Errorf("unable to process byte stream: %v", err)
 	}

 	return dec.process(s, reflect.StructTag(""))
 }

 func (dec *Decoder) process(s interface{}, tag reflect.StructTag) error {
 	// Scan for conformant fields as their max counts are moved to the beginning
 	// http://pubs.opengroup.org/onlinepubs/9629399/chap14.htm#tagfcjh_37
 	err := dec.scanConformantArrays(s, tag)
 	if err != nil {
 		return err
 	}
 	// Recursively fill the struct fields
 	var localDef []deferedPtr
 	err = dec.fill(s, tag, &localDef)
 	if err != nil {
 		return Errorf("could not decode: %v", err)
 	}
 	// Read any deferred referents associated with pointers
 	for _, p := range localDef {
 		err = dec.process(p.v, p.tag)
 		if err != nil {
 			return fmt.Errorf("could not decode deferred referent: %v", err)
 		}
 	}
 	return nil
 }

 // scanConformantArrays scans the structure for embedded conformant fields and captures the maximum element counts for
 // dimensions of the array that are moved to the beginning of the structure.
 func (dec *Decoder) scanConformantArrays(s interface{}, tag reflect.StructTag) error {
 	err := dec.conformantScan(s, tag)
 	if err != nil {
 		return fmt.Errorf("failed to scan for embedded conformant arrays: %v", err)
 	}
 	for i := range dec.conformantMax {
 		dec.conformantMax[i], err = dec.readUint32()
 		if err != nil {
 			return fmt.Errorf("could not read preceding conformant max count index %d: %v", i, err)
 		}
 	}
 	return nil
 }

 // conformantScan inspects the structure's fields for whether they are conformant.
 func (dec *Decoder) conformantScan(s interface{}, tag reflect.StructTag) error {
 	ndrTag := parseTags(tag)
 	if ndrTag.HasValue(TagPointer) {
 		return nil
 	}
 	v := getReflectValue(s)
 	switch v.Kind() {
 	case reflect.Struct:
 		for i := 0; i < v.NumField(); i++ {
 			err := dec.conformantScan(v.Field(i), v.Type().Field(i).Tag)
 			if err != nil {
 				return err
 			}
 		}
 	case reflect.String:
 		if !ndrTag.HasValue(TagConformant) {
 			break
 		}
 		dec.conformantMax = append(dec.conformantMax, uint32(0))
 	case reflect.Slice:
 		if !ndrTag.HasValue(TagConformant) {
 			break
 		}
 		d, t := sliceDimensions(v.Type())
 		for i := 0; i < d; i++ {
 			dec.conformantMax = append(dec.conformantMax, uint32(0))
 		}
 		// For string arrays there is a common max for the strings within the array.
 		if t.Kind() == reflect.String {
 			dec.conformantMax = append(dec.conformantMax, uint32(0))
 		}
 	}
 	return nil
 }

 func (dec *Decoder) isPointer(v reflect.Value, tag reflect.StructTag, def *[]deferedPtr) (bool, error) {
 	// Pointer so defer filling the referent
 	ndrTag := parseTags(tag)
 	if ndrTag.HasValue(TagPointer) {
 		p, err := dec.readUint32()
 		if err != nil {
 			return true, fmt.Errorf("could not read pointer: %v", err)
 		}
 		ndrTag.delete(TagPointer)
 		if p != 0 {
 			// if pointer is not zero add to the deferred items at end of stream
 			*def = append(*def, deferedPtr{v, ndrTag.StructTag()})
 		}
 		return true, nil
 	}
 	return false, nil
 }

 func getReflectValue(s interface{}) (v reflect.Value) {
 	if r, ok := s.(reflect.Value); ok {
 		v = r
 	} else {
 		if reflect.ValueOf(s).Kind() == reflect.Ptr {
 			v = reflect.ValueOf(s).Elem()
 		}
 	}
 	return
 }

 // fill populates fields with values from the NDR byte stream.
 func (dec *Decoder) fill(s interface{}, tag reflect.StructTag, localDef *[]deferedPtr) error {
 	v := getReflectValue(s)

 	//// Pointer so defer filling the referent
 	ptr, err := dec.isPointer(v, tag, localDef)
 	if err != nil {
 		return fmt.Errorf("could not process struct field(%s): %v", strings.Join(dec.current, "/"), err)
 	}
 	if ptr {
 		return nil
 	}

 	// Populate the value from the byte stream
 	switch v.Kind() {
 	case reflect.Struct:
 		dec.current = append(dec.current, v.Type().Name()) //Track the current field being filled
 		// in case struct is a union, track this and the selected union field for efficiency
 		var unionTag reflect.Value
 		var unionField string // field to fill if struct is a union
 		// Go through each field in the struct and recursively fill
 		for i := 0; i < v.NumField(); i++ {
 			fieldName := v.Type().Field(i).Name
 			dec.current = append(dec.current, fieldName) //Track the current field being filled
 			//fmt.Fprintf(os.Stderr, "DEBUG Decoding: %s\n", strings.Join(dec.current, "/"))
 			structTag := v.Type().Field(i).Tag
 			ndrTag := parseTags(structTag)

 			// Union handling
 			if !unionTag.IsValid() {
 				// Is this field a union tag?
 				unionTag = dec.isUnion(v.Field(i), structTag)
 			} else {
 				// What is the selected field value of the union if we don't already know
 				if unionField == "" {
 					unionField, err = unionSelectedField(v, unionTag)
 					if err != nil {
 						return fmt.Errorf("could not determine selected union value field for %s with discriminat"+
 							" tag %s: %v", v.Type().Name(), unionTag, err)
 					}
 				}
 				if ndrTag.HasValue(TagUnionField) && fieldName != unionField {
 					// is a union and this field has not been selected so will skip it.
 					dec.current = dec.current[:len(dec.current)-1] //This field has been skipped so remove it from the current field tracker
 					continue
 				}
 			}

 			// Check if field is a pointer
 			if v.Field(i).Type().Implements(reflect.TypeOf(new(RawBytes)).Elem()) &&
 				v.Field(i).Type().Kind() == reflect.Slice && v.Field(i).Type().Elem().Kind() == reflect.Uint8 {
 				//field is for rawbytes
 				structTag, err = addSizeToTag(v, v.Field(i), structTag)
 				if err != nil {
 					return fmt.Errorf("could not get rawbytes field(%s) size: %v", strings.Join(dec.current, "/"), err)
 				}
 				ptr, err := dec.isPointer(v.Field(i), structTag, localDef)
 				if err != nil {
 					return fmt.Errorf("could not process struct field(%s): %v", strings.Join(dec.current, "/"), err)
 				}
 				if !ptr {
 					err := dec.readRawBytes(v.Field(i), structTag)
 					if err != nil {
 						return fmt.Errorf("could not fill raw bytes struct field(%s): %v", strings.Join(dec.current, "/"), err)
 					}
 				}
 			} else {
 				err := dec.fill(v.Field(i), structTag, localDef)
 				if err != nil {
 					return fmt.Errorf("could not fill struct field(%s): %v", strings.Join(dec.current, "/"), err)
 				}
 			}
 			dec.current = dec.current[:len(dec.current)-1] //This field has been filled so remove it from the current field tracker
 		}
 		dec.current = dec.current[:len(dec.current)-1] //This field has been filled so remove it from the current field tracker
 	case reflect.Bool:
 		i, err := dec.readBool()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Uint8:
 		i, err := dec.readUint8()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Uint16:
 		i, err := dec.readUint16()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Uint32:
 		i, err := dec.readUint32()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Uint64:
 		i, err := dec.readUint64()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Int8:
 		i, err := dec.readInt8()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Int16:
 		i, err := dec.readInt16()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Int32:
 		i, err := dec.readInt32()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Int64:
 		i, err := dec.readInt64()
 		if err != nil {
 			return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.String:
 		ndrTag := parseTags(tag)
 		conformant := ndrTag.HasValue(TagConformant)
 		// strings are always varying so this is assumed without an explicit tag
 		var s string
 		var err error
 		if conformant {
 			s, err = dec.readConformantVaryingString(localDef)
 			if err != nil {
 				return fmt.Errorf("could not fill with conformant varying string: %v", err)
 			}
 		} else {
 			s, err = dec.readVaryingString(localDef)
 			if err != nil {
 				return fmt.Errorf("could not fill with varying string: %v", err)
 			}
 		}
 		v.Set(reflect.ValueOf(s))
 	case reflect.Float32:
 		i, err := dec.readFloat32()
 		if err != nil {
 			return fmt.Errorf("could not fill %v: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Float64:
 		i, err := dec.readFloat64()
 		if err != nil {
 			return fmt.Errorf("could not fill %v: %v", v.Type().Name(), err)
 		}
 		v.Set(reflect.ValueOf(i))
 	case reflect.Array:
 		err := dec.fillFixedArray(v, tag, localDef)
 		if err != nil {
 			return err
 		}
 	case reflect.Slice:
 		if v.Type().Implements(reflect.TypeOf(new(RawBytes)).Elem()) && v.Type().Elem().Kind() == reflect.Uint8 {
 			//field is for rawbytes
 			err := dec.readRawBytes(v, tag)
 			if err != nil {
 				return fmt.Errorf("could not fill raw bytes struct field(%s): %v", strings.Join(dec.current, "/"), err)
 			}
 			break
 		}
 		ndrTag := parseTags(tag)
 		conformant := ndrTag.HasValue(TagConformant)
 		varying := ndrTag.HasValue(TagVarying)
 		if ndrTag.HasValue(TagPipe) {
 			err := dec.fillPipe(v, tag)
 			if err != nil {
 				return err
 			}
 			break
 		}
 		_, t := sliceDimensions(v.Type())
 		if t.Kind() == reflect.String && !ndrTag.HasValue(subStringArrayValue) {
 			// String array
 			err := dec.readStringsArray(v, tag, localDef)
 			if err != nil {
 				return err
 			}
 			break
 		}
 		// varying is assumed as fixed arrays use the Go array type rather than slice
 		if conformant && varying {
 			err := dec.fillConformantVaryingArray(v, tag, localDef)
 			if err != nil {
 				return err
 			}
 		} else if !conformant && varying {
 			err := dec.fillVaryingArray(v, tag, localDef)
 			if err != nil {
 				return err
 			}
 		} else {
 			//default to conformant and not varying
 			err := dec.fillConformantArray(v, tag, localDef)
 			if err != nil {
 				return err
 			}
 		}
 	default:
 		return fmt.Errorf("unsupported type")
 	}
 	return nil
 }

 // readBytes returns a number of bytes from the NDR byte stream.
 func (dec *Decoder) readBytes(n int) ([]byte, error) {
 	//TODO make this take an int64 as input to allow for larger values on all systems?
 	b := make([]byte, n, n)
 	m, err := dec.r.Read(b)
 	if err != nil || m != n {
 		return b, fmt.Errorf("error reading bytes from stream: %v", err)
 	}
 	return b, nil
 }
	// Package ndr provides the ability to unmarshal NDR encoded byte steams into Go data structures
	package ndr

	import (
	"bufio"
	"fmt"
	"io"
	"reflect"
	"strings"
	)

	// Struct tag values
	const (
	TagConformant = "conformant"
	TagVarying = "varying"
	TagPointer = "pointer"
	TagPipe = "pipe"
	)

	// Decoder unmarshals NDR byte stream data into a Go struct representation
	type Decoder struct {
	r *bufio.Reader // source of the data
	size int // initial size of bytes in buffer
	ch CommonHeader // NDR common header
	ph PrivateHeader // NDR private header
	conformantMax []uint32 // conformant max values that were moved to the beginning of the structure
	s interface{} // pointer to the structure being populated
	current []string // keeps track of the current field being populated
	}

	type deferedPtr struct {
	v reflect.Value
	tag reflect.StructTag
	}

	// NewDecoder creates a new instance of a NDR Decoder.
	func NewDecoder(r io.Reader) *Decoder {
	dec := new(Decoder)
	dec.r = bufio.NewReader(r)
	dec.r.Peek(int(commonHeaderBytes)) // For some reason an operation is needed on the buffer to initialise it so Buffered() != 0
	dec.size = dec.r.Buffered()
	return dec
	}

	// Decode unmarshals the NDR encoded bytes into the pointer of a struct provided.
	func (dec *Decoder) Decode(s interface{}) error {
	dec.s = s
	err := dec.readCommonHeader()
	if err != nil {
	return err
	}
	err = dec.readPrivateHeader()
	if err != nil {
	return err
	}
	_, err = dec.r.Discard(4) //The next 4 bytes are an RPC unique pointer referent. We just skip these.
	if err != nil {
	return Errorf("unable to process byte stream: %v", err)
	}

	return dec.process(s, reflect.StructTag(""))
	}

	func (dec *Decoder) process(s interface{}, tag reflect.StructTag) error {
	// Scan for conformant fields as their max counts are moved to the beginning
	// http://pubs.opengroup.org/onlinepubs/9629399/chap14.htm#tagfcjh_37
	err := dec.scanConformantArrays(s, tag)
	if err != nil {
	return err
	}
	// Recursively fill the struct fields
	var localDef []deferedPtr
	err = dec.fill(s, tag, &localDef)
	if err != nil {
	return Errorf("could not decode: %v", err)
	}
	// Read any deferred referents associated with pointers
	for _, p := range localDef {
	err = dec.process(p.v, p.tag)
	if err != nil {
	return fmt.Errorf("could not decode deferred referent: %v", err)
	}
	}
	return nil
	}

	// scanConformantArrays scans the structure for embedded conformant fields and captures the maximum element counts for
	// dimensions of the array that are moved to the beginning of the structure.
	func (dec *Decoder) scanConformantArrays(s interface{}, tag reflect.StructTag) error {
	err := dec.conformantScan(s, tag)
	if err != nil {
	return fmt.Errorf("failed to scan for embedded conformant arrays: %v", err)
	}
	for i := range dec.conformantMax {
	dec.conformantMax[i], err = dec.readUint32()
	if err != nil {
	return fmt.Errorf("could not read preceding conformant max count index %d: %v", i, err)
	}
	}
	return nil
	}

	// conformantScan inspects the structure's fields for whether they are conformant.
	func (dec *Decoder) conformantScan(s interface{}, tag reflect.StructTag) error {
	ndrTag := parseTags(tag)
	if ndrTag.HasValue(TagPointer) {
	return nil
	}
	v := getReflectValue(s)
	switch v.Kind() {
	case reflect.Struct:
	for i := 0; i < v.NumField(); i++ {
	err := dec.conformantScan(v.Field(i), v.Type().Field(i).Tag)
	if err != nil {
	return err
	}
	}
	case reflect.String:
	if !ndrTag.HasValue(TagConformant) {
	break
	}
	dec.conformantMax = append(dec.conformantMax, uint32(0))
	case reflect.Slice:
	if !ndrTag.HasValue(TagConformant) {
	break
	}
	d, t := sliceDimensions(v.Type())
	for i := 0; i < d; i++ {
	dec.conformantMax = append(dec.conformantMax, uint32(0))
	}
	// For string arrays there is a common max for the strings within the array.
	if t.Kind() == reflect.String {
	dec.conformantMax = append(dec.conformantMax, uint32(0))
	}
	}
	return nil
	}

	func (dec Decoder) isPointer(v reflect.Value, tag reflect.StructTag, def []deferedPtr) (bool, error) {
	// Pointer so defer filling the referent
	ndrTag := parseTags(tag)
	if ndrTag.HasValue(TagPointer) {
	p, err := dec.readUint32()
	if err != nil {
	return true, fmt.Errorf("could not read pointer: %v", err)
	}
	ndrTag.delete(TagPointer)
	if p != 0 {
	// if pointer is not zero add to the deferred items at end of stream
	def = append(def, deferedPtr{v, ndrTag.StructTag()})
	}
	return true, nil
	}
	return false, nil
	}

	func getReflectValue(s interface{}) (v reflect.Value) {
	if r, ok := s.(reflect.Value); ok {
	v = r
	} else {
	if reflect.ValueOf(s).Kind() == reflect.Ptr {
	v = reflect.ValueOf(s).Elem()
	}
	}
	return
	}

	// fill populates fields with values from the NDR byte stream.
	func (dec Decoder) fill(s interface{}, tag reflect.StructTag, localDef []deferedPtr) error {
	v := getReflectValue(s)

	//// Pointer so defer filling the referent
	ptr, err := dec.isPointer(v, tag, localDef)
	if err != nil {
	return fmt.Errorf("could not process struct field(%s): %v", strings.Join(dec.current, "/"), err)
	}
	if ptr {
	return nil
	}

	// Populate the value from the byte stream
	switch v.Kind() {
	case reflect.Struct:
	dec.current = append(dec.current, v.Type().Name()) //Track the current field being filled
	// in case struct is a union, track this and the selected union field for efficiency
	var unionTag reflect.Value
	var unionField string // field to fill if struct is a union
	// Go through each field in the struct and recursively fill
	for i := 0; i < v.NumField(); i++ {
	fieldName := v.Type().Field(i).Name
	dec.current = append(dec.current, fieldName) //Track the current field being filled
	//fmt.Fprintf(os.Stderr, "DEBUG Decoding: %s\n", strings.Join(dec.current, "/"))
	structTag := v.Type().Field(i).Tag
	ndrTag := parseTags(structTag)

	// Union handling
	if !unionTag.IsValid() {
	// Is this field a union tag?
	unionTag = dec.isUnion(v.Field(i), structTag)
	} else {
	// What is the selected field value of the union if we don't already know
	if unionField == "" {
	unionField, err = unionSelectedField(v, unionTag)
	if err != nil {
	return fmt.Errorf("could not determine selected union value field for %s with discriminat"+
	" tag %s: %v", v.Type().Name(), unionTag, err)
	}
	}
	if ndrTag.HasValue(TagUnionField) && fieldName != unionField {
	// is a union and this field has not been selected so will skip it.
	dec.current = dec.current[:len(dec.current)-1] //This field has been skipped so remove it from the current field tracker
	continue
	}
	}

	// Check if field is a pointer
	if v.Field(i).Type().Implements(reflect.TypeOf(new(RawBytes)).Elem()) &&
	v.Field(i).Type().Kind() == reflect.Slice && v.Field(i).Type().Elem().Kind() == reflect.Uint8 {
	//field is for rawbytes
	structTag, err = addSizeToTag(v, v.Field(i), structTag)
	if err != nil {
	return fmt.Errorf("could not get rawbytes field(%s) size: %v", strings.Join(dec.current, "/"), err)
	}
	ptr, err := dec.isPointer(v.Field(i), structTag, localDef)
	if err != nil {
	return fmt.Errorf("could not process struct field(%s): %v", strings.Join(dec.current, "/"), err)
	}
	if !ptr {
	err := dec.readRawBytes(v.Field(i), structTag)
	if err != nil {
	return fmt.Errorf("could not fill raw bytes struct field(%s): %v", strings.Join(dec.current, "/"), err)
	}
	}
	} else {
	err := dec.fill(v.Field(i), structTag, localDef)
	if err != nil {
	return fmt.Errorf("could not fill struct field(%s): %v", strings.Join(dec.current, "/"), err)
	}
	}
	dec.current = dec.current[:len(dec.current)-1] //This field has been filled so remove it from the current field tracker
	}
	dec.current = dec.current[:len(dec.current)-1] //This field has been filled so remove it from the current field tracker
	case reflect.Bool:
	i, err := dec.readBool()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Uint8:
	i, err := dec.readUint8()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Uint16:
	i, err := dec.readUint16()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Uint32:
	i, err := dec.readUint32()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Uint64:
	i, err := dec.readUint64()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Int8:
	i, err := dec.readInt8()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Int16:
	i, err := dec.readInt16()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Int32:
	i, err := dec.readInt32()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Int64:
	i, err := dec.readInt64()
	if err != nil {
	return fmt.Errorf("could not fill %s: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.String:
	ndrTag := parseTags(tag)
	conformant := ndrTag.HasValue(TagConformant)
	// strings are always varying so this is assumed without an explicit tag
	var s string
	var err error
	if conformant {
	s, err = dec.readConformantVaryingString(localDef)
	if err != nil {
	return fmt.Errorf("could not fill with conformant varying string: %v", err)
	}
	} else {
	s, err = dec.readVaryingString(localDef)
	if err != nil {
	return fmt.Errorf("could not fill with varying string: %v", err)
	}
	}
	v.Set(reflect.ValueOf(s))
	case reflect.Float32:
	i, err := dec.readFloat32()
	if err != nil {
	return fmt.Errorf("could not fill %v: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Float64:
	i, err := dec.readFloat64()
	if err != nil {
	return fmt.Errorf("could not fill %v: %v", v.Type().Name(), err)
	}
	v.Set(reflect.ValueOf(i))
	case reflect.Array:
	err := dec.fillFixedArray(v, tag, localDef)
	if err != nil {
	return err
	}
	case reflect.Slice:
	if v.Type().Implements(reflect.TypeOf(new(RawBytes)).Elem()) && v.Type().Elem().Kind() == reflect.Uint8 {
	//field is for rawbytes
	err := dec.readRawBytes(v, tag)
	if err != nil {
	return fmt.Errorf("could not fill raw bytes struct field(%s): %v", strings.Join(dec.current, "/"), err)
	}
	break
	}
	ndrTag := parseTags(tag)
	conformant := ndrTag.HasValue(TagConformant)
	varying := ndrTag.HasValue(TagVarying)
	if ndrTag.HasValue(TagPipe) {
	err := dec.fillPipe(v, tag)
	if err != nil {
	return err
	}
	break
	}
	_, t := sliceDimensions(v.Type())
	if t.Kind() == reflect.String && !ndrTag.HasValue(subStringArrayValue) {
	// String array
	err := dec.readStringsArray(v, tag, localDef)
	if err != nil {
	return err
	}
	break
	}
	// varying is assumed as fixed arrays use the Go array type rather than slice
	if conformant && varying {
	err := dec.fillConformantVaryingArray(v, tag, localDef)
	if err != nil {
	return err
	}
	} else if !conformant && varying {
	err := dec.fillVaryingArray(v, tag, localDef)
	if err != nil {
	return err
	}
	} else {
	//default to conformant and not varying
	err := dec.fillConformantArray(v, tag, localDef)
	if err != nil {
	return err
	}
	}
	default:
	return fmt.Errorf("unsupported type")
	}
	return nil
	}

	// readBytes returns a number of bytes from the NDR byte stream.
	func (dec *Decoder) readBytes(n int) ([]byte, error) {
	//TODO make this take an int64 as input to allow for larger values on all systems?
	b := make([]byte, n, n)
	m, err := dec.r.Read(b)
	if err != nil \|\| m != n {
	return b, fmt.Errorf("error reading bytes from stream: %v", err)
	}
	return b, nil
	}