20 // Sum of bytes used to Decode values.
25 func (d *Decoder) Decode(v interface{}) (err error) {
31 _, ok := r.(runtime.Error)
41 pv := reflect.ValueOf(v)
42 if pv.Kind() != reflect.Ptr || pv.IsNil() {
43 return &UnmarshalInvalidArgError{reflect.TypeOf(v)}
46 ok, err := d.parseValue(pv.Elem())
51 d.throwSyntaxError(d.Offset-1, errors.New("unexpected 'e'"))
56 func checkForUnexpectedEOF(err error, offset int64) {
60 What: io.ErrUnexpectedEOF,
65 func (d *Decoder) readByte() byte {
66 b, err := d.r.ReadByte()
68 checkForUnexpectedEOF(err, d.Offset)
76 // reads data writing it to 'd.buf' until 'sep' byte is encountered, 'sep' byte
77 // is consumed, but not included into the 'd.buf'
78 func (d *Decoder) readUntil(sep byte) {
88 func checkForIntParseError(err error, offset int64) {
97 func (d *Decoder) throwSyntaxError(offset int64, err error) {
104 // Assume the 'i' is already consumed. Read and validate the rest of an int into the buffer.
105 func (d *Decoder) readInt() error {
106 // start := d.Offset - 1
108 if err := d.bufLeadingZero(); err != nil {
111 // if d.buf.Len() == 0 {
112 // panic(&SyntaxError{
114 // What: errors.New("empty integer value"),
120 // called when 'i' was consumed, for the integer type in v.
121 func (d *Decoder) parseInt(v reflect.Value) error {
122 start := d.Offset - 1
124 if err := d.readInt(); err != nil {
127 s := bytesAsString(d.buf.Bytes())
130 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
131 n, err := strconv.ParseInt(s, 10, 64)
132 checkForIntParseError(err, start)
134 if v.OverflowInt(n) {
135 return &UnmarshalTypeError{
136 BencodeTypeName: "int",
137 UnmarshalTargetType: v.Type(),
141 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
142 n, err := strconv.ParseUint(s, 10, 64)
143 checkForIntParseError(err, start)
145 if v.OverflowUint(n) {
146 return &UnmarshalTypeError{
147 BencodeTypeName: "int",
148 UnmarshalTargetType: v.Type(),
155 return &UnmarshalTypeError{
156 BencodeTypeName: "int",
157 UnmarshalTargetType: v.Type(),
164 func (d *Decoder) bufLeadingZero() error {
166 if len(b) > 1 && b[0] == '0' {
167 return fmt.Errorf("non-zero integer has leading zeroes: %q", b)
172 func (d *Decoder) parseStringLength() (uint64, error) {
173 // We should have already consumed the first byte of the length into the Decoder buf.
174 start := d.Offset - 1
176 if err := d.bufLeadingZero(); err != nil {
179 length, err := strconv.ParseUint(bytesAsString(d.buf.Bytes()), 10, 32)
180 checkForIntParseError(err, start)
185 func (d *Decoder) parseString(v reflect.Value) error {
186 length, err := d.parseStringLength()
191 read := func(b []byte) {
192 n, err := io.ReadFull(d.r, b)
195 checkForUnexpectedEOF(err, d.Offset)
198 What: errors.New("unexpected I/O error: " + err.Error()),
205 b := make([]byte, length)
207 v.SetString(bytesAsString(b))
210 if v.Type().Elem().Kind() != reflect.Uint8 {
213 b := make([]byte, length)
218 if v.Type().Elem().Kind() != reflect.Uint8 {
221 d.buf.Grow(int(length))
222 b := d.buf.Bytes()[:length]
224 reflect.Copy(v, reflect.ValueOf(b))
227 d.buf.Grow(int(length))
228 read(d.buf.Bytes()[:length])
229 // I believe we return here to support "ignore_unmarshal_type_error".
230 return &UnmarshalTypeError{
231 BencodeTypeName: "string",
232 UnmarshalTargetType: v.Type(),
236 // Info for parsing a dict value.
237 type dictField struct {
239 Get func(value reflect.Value) func(reflect.Value)
243 // Returns specifics for parsing a dict field value.
244 func getDictField(dict reflect.Type, key string) (_ dictField, err error) {
245 // get valuev as a map value or as a struct field
246 switch k := dict.Kind(); k {
250 Get: func(mapValue reflect.Value) func(reflect.Value) {
251 return func(value reflect.Value) {
252 if mapValue.IsNil() {
253 mapValue.Set(reflect.MakeMap(dict))
255 // Assigns the value into the map.
256 // log.Printf("map type: %v", mapValue.Type())
257 mapValue.SetMapIndex(reflect.ValueOf(key).Convert(dict.Key()), value)
262 return getStructFieldForKey(dict, key), nil
263 // if sf.r.PkgPath != "" {
264 // panic(&UnmarshalFieldError{
266 // Type: dict.Type(),
271 err = fmt.Errorf("can't assign bencode dict items into a %v", k)
277 structFieldsMu sync.Mutex
278 structFields = map[reflect.Type]map[string]dictField{}
281 func parseStructFields(struct_ reflect.Type, each func(key string, df dictField)) {
282 for _i, n := 0, struct_.NumField(); _i < n; _i++ {
284 f := struct_.Field(i)
287 if t.Kind() == reflect.Ptr {
290 parseStructFields(t, func(key string, df dictField) {
292 df.Get = func(value reflect.Value) func(reflect.Value) {
293 anonPtr := value.Field(i)
294 if anonPtr.Kind() == reflect.Ptr && anonPtr.IsNil() {
295 anonPtr.Set(reflect.New(f.Type.Elem()))
296 anonPtr = anonPtr.Elem()
298 return innerGet(anonPtr)
304 tagStr := f.Tag.Get("bencode")
308 tag := parseTag(tagStr)
313 each(key, dictField{f.Type, func(value reflect.Value) func(reflect.Value) {
314 return value.Field(i).Set
319 func saveStructFields(struct_ reflect.Type) {
320 m := make(map[string]dictField)
321 parseStructFields(struct_, func(key string, sf dictField) {
324 structFields[struct_] = m
327 func getStructFieldForKey(struct_ reflect.Type, key string) (f dictField) {
328 structFieldsMu.Lock()
329 if _, ok := structFields[struct_]; !ok {
330 saveStructFields(struct_)
332 f, ok := structFields[struct_][key]
333 structFieldsMu.Unlock()
335 var discard interface{}
337 Type: reflect.TypeOf(discard),
338 Get: func(reflect.Value) func(reflect.Value) { return func(reflect.Value) {} },
345 func (d *Decoder) parseDict(v reflect.Value) error {
346 // At this point 'd' byte was consumed, now read key/value pairs
349 keyValue := reflect.ValueOf(&keyStr).Elem()
350 ok, err := d.parseValue(keyValue)
352 return fmt.Errorf("error parsing dict key: %w", err)
358 df, err := getDictField(v.Type(), keyStr)
360 return fmt.Errorf("parsing bencode dict into %v: %w", v.Type(), err)
363 // now we need to actually parse it
365 // Discard the value, there's nowhere to put it.
367 if_, ok = d.parseValueInterface()
369 return fmt.Errorf("error parsing value for key %q", keyStr)
372 return fmt.Errorf("missing value for key %q", keyStr)
376 setValue := reflect.New(df.Type).Elem()
377 // log.Printf("parsing into %v", setValue.Type())
378 ok, err = d.parseValue(setValue)
380 var target *UnmarshalTypeError
381 if !(errors.As(err, &target) && df.Tags.IgnoreUnmarshalTypeError()) {
382 return fmt.Errorf("parsing value for key %q: %w", keyStr, err)
386 return fmt.Errorf("missing value for key %q", keyStr)
392 func (d *Decoder) parseList(v reflect.Value) error {
395 // If the list is a singleton of the expected type, use that value. See
396 // https://github.com/anacrolix/torrent/issues/297.
397 l := reflect.New(reflect.SliceOf(v.Type()))
398 if err := d.parseList(l.Elem()); err != nil {
401 if l.Elem().Len() != 1 {
402 return &UnmarshalTypeError{
403 BencodeTypeName: "list",
404 UnmarshalTargetType: v.Type(),
407 v.Set(l.Elem().Index(0))
409 case reflect.Array, reflect.Slice:
410 // We can work with this. Normal case, fallthrough.
415 if v.Kind() == reflect.Slice && i >= v.Len() {
416 v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
420 ok, err := d.parseValue(v.Index(i))
428 _, ok := d.parseValueInterface()
436 if v.Kind() == reflect.Array {
437 z := reflect.Zero(v.Type().Elem())
438 for n := v.Len(); i < n; i++ {
446 if i == 0 && v.Kind() == reflect.Slice {
447 v.Set(reflect.MakeSlice(v.Type(), 0, 0))
452 func (d *Decoder) readOneValue() bool {
453 b, err := d.r.ReadByte()
467 // read until there is nothing to read
468 for d.readOneValue() {
470 // consume 'e' as well
475 d.buf.WriteString("e")
477 if b >= '0' && b <= '9' {
478 start := d.buf.Len() - 1
480 length, err := strconv.ParseInt(bytesAsString(d.buf.Bytes()[start:]), 10, 64)
481 checkForIntParseError(err, d.Offset-1)
483 d.buf.WriteString(":")
484 n, err := io.CopyN(&d.buf, d.r, length)
487 checkForUnexpectedEOF(err, d.Offset)
490 What: errors.New("unexpected I/O error: " + err.Error()),
496 d.raiseUnknownValueType(b, d.Offset-1)
502 func (d *Decoder) parseUnmarshaler(v reflect.Value) bool {
503 if !v.Type().Implements(unmarshalerType) {
504 if v.Addr().Type().Implements(unmarshalerType) {
511 if !d.readOneValue() {
514 m := v.Interface().(Unmarshaler)
515 err := m.UnmarshalBencode(d.buf.Bytes())
517 panic(&UnmarshalerError{v.Type(), err})
522 // Returns true if there was a value and it's now stored in 'v', otherwise
523 // there was an end symbol ("e") and no value was stored.
524 func (d *Decoder) parseValue(v reflect.Value) (bool, error) {
525 // we support one level of indirection at the moment
526 if v.Kind() == reflect.Ptr {
527 // if the pointer is nil, allocate a new element of the type it
530 v.Set(reflect.New(v.Type().Elem()))
535 if d.parseUnmarshaler(v) {
539 // common case: interface{}
540 if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
541 iface, _ := d.parseValueInterface()
542 v.Set(reflect.ValueOf(iface))
546 b, err := d.r.ReadByte()
556 return true, d.parseDict(v)
558 return true, d.parseList(v)
560 return true, d.parseInt(v)
562 if b >= '0' && b <= '9' {
565 // Write the first digit of the length to the buffer.
567 return true, d.parseString(v)
570 d.raiseUnknownValueType(b, d.Offset-1)
575 // An unknown bencode type character was encountered.
576 func (d *Decoder) raiseUnknownValueType(b byte, offset int64) {
579 What: fmt.Errorf("unknown value type %+q", b),
583 func (d *Decoder) parseValueInterface() (interface{}, bool) {
584 b, err := d.r.ReadByte()
594 return d.parseDictInterface(), true
596 return d.parseListInterface(), true
598 return d.parseIntInterface(), true
600 if b >= '0' && b <= '9' {
602 // append first digit of the length to the buffer
604 return d.parseStringInterface(), true
607 d.raiseUnknownValueType(b, d.Offset-1)
612 // Called after 'i', for an arbitrary integer size.
613 func (d *Decoder) parseIntInterface() (ret interface{}) {
614 start := d.Offset - 1
616 if err := d.readInt(); err != nil {
619 n, err := strconv.ParseInt(d.buf.String(), 10, 64)
620 if ne, ok := err.(*strconv.NumError); ok && ne.Err == strconv.ErrRange {
622 _, ok := i.SetString(d.buf.String(), 10)
626 What: errors.New("failed to parse integer"),
631 checkForIntParseError(err, start)
639 func (d *Decoder) parseStringInterface() string {
640 length, err := d.parseStringLength()
644 b := make([]byte, length)
645 n, err := io.ReadFull(d.r, b)
648 panic(&SyntaxError{Offset: d.Offset, What: err})
650 return bytesAsString(b)
653 func (d *Decoder) parseDictInterface() interface{} {
654 dict := make(map[string]interface{})
658 keyi, ok := d.parseValueInterface()
663 key, ok := keyi.(string)
667 What: errors.New("non-string key in a dict"),
671 d.throwSyntaxError(start, fmt.Errorf("dict keys unsorted: %q <= %q", key, lastKey))
674 valuei, ok := d.parseValueInterface()
676 d.throwSyntaxError(start, fmt.Errorf("dict elem missing value [key=%v]", key))
685 func (d *Decoder) parseListInterface() (list []interface{}) {
686 list = []interface{}{}
687 valuei, ok := d.parseValueInterface()
689 list = append(list, valuei)
690 valuei, ok = d.parseValueInterface()