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.checkBufferedInt(); 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) checkBufferedInt() error {
172 if b[0] < '1' || b[0] > '9' {
173 return errors.New("invalid leading digit")
178 func (d *Decoder) parseStringLength() (uint64, error) {
179 // We should have already consumed the first byte of the length into the Decoder buf.
180 start := d.Offset - 1
182 if err := d.checkBufferedInt(); err != nil {
185 length, err := strconv.ParseUint(bytesAsString(d.buf.Bytes()), 10, 32)
186 checkForIntParseError(err, start)
191 func (d *Decoder) parseString(v reflect.Value) error {
192 length, err := d.parseStringLength()
197 read := func(b []byte) {
198 n, err := io.ReadFull(d.r, b)
201 checkForUnexpectedEOF(err, d.Offset)
204 What: errors.New("unexpected I/O error: " + err.Error()),
211 b := make([]byte, length)
213 v.SetString(bytesAsString(b))
216 if v.Type().Elem().Kind() != reflect.Uint8 {
219 b := make([]byte, length)
224 if v.Type().Elem().Kind() != reflect.Uint8 {
227 d.buf.Grow(int(length))
228 b := d.buf.Bytes()[:length]
230 reflect.Copy(v, reflect.ValueOf(b))
233 d.buf.Grow(int(length))
234 read(d.buf.Bytes()[:length])
235 // I believe we return here to support "ignore_unmarshal_type_error".
236 return &UnmarshalTypeError{
237 BencodeTypeName: "string",
238 UnmarshalTargetType: v.Type(),
242 // Info for parsing a dict value.
243 type dictField struct {
245 Get func(value reflect.Value) func(reflect.Value)
249 // Returns specifics for parsing a dict field value.
250 func getDictField(dict reflect.Type, key string) (_ dictField, err error) {
251 // get valuev as a map value or as a struct field
252 switch k := dict.Kind(); k {
256 Get: func(mapValue reflect.Value) func(reflect.Value) {
257 return func(value reflect.Value) {
258 if mapValue.IsNil() {
259 mapValue.Set(reflect.MakeMap(dict))
261 // Assigns the value into the map.
262 // log.Printf("map type: %v", mapValue.Type())
263 mapValue.SetMapIndex(reflect.ValueOf(key).Convert(dict.Key()), value)
268 return getStructFieldForKey(dict, key), nil
269 // if sf.r.PkgPath != "" {
270 // panic(&UnmarshalFieldError{
272 // Type: dict.Type(),
277 err = fmt.Errorf("can't assign bencode dict items into a %v", k)
283 structFieldsMu sync.Mutex
284 structFields = map[reflect.Type]map[string]dictField{}
287 func parseStructFields(struct_ reflect.Type, each func(key string, df dictField)) {
288 for _i, n := 0, struct_.NumField(); _i < n; _i++ {
290 f := struct_.Field(i)
293 if t.Kind() == reflect.Ptr {
296 parseStructFields(t, func(key string, df dictField) {
298 df.Get = func(value reflect.Value) func(reflect.Value) {
299 anonPtr := value.Field(i)
300 if anonPtr.Kind() == reflect.Ptr && anonPtr.IsNil() {
301 anonPtr.Set(reflect.New(f.Type.Elem()))
302 anonPtr = anonPtr.Elem()
304 return innerGet(anonPtr)
310 tagStr := f.Tag.Get("bencode")
314 tag := parseTag(tagStr)
319 each(key, dictField{f.Type, func(value reflect.Value) func(reflect.Value) {
320 return value.Field(i).Set
325 func saveStructFields(struct_ reflect.Type) {
326 m := make(map[string]dictField)
327 parseStructFields(struct_, func(key string, sf dictField) {
330 structFields[struct_] = m
333 func getStructFieldForKey(struct_ reflect.Type, key string) (f dictField) {
334 structFieldsMu.Lock()
335 if _, ok := structFields[struct_]; !ok {
336 saveStructFields(struct_)
338 f, ok := structFields[struct_][key]
339 structFieldsMu.Unlock()
341 var discard interface{}
343 Type: reflect.TypeOf(discard),
344 Get: func(reflect.Value) func(reflect.Value) { return func(reflect.Value) {} },
351 func (d *Decoder) parseDict(v reflect.Value) error {
352 // At this point 'd' byte was consumed, now read key/value pairs
355 keyValue := reflect.ValueOf(&keyStr).Elem()
356 ok, err := d.parseValue(keyValue)
358 return fmt.Errorf("error parsing dict key: %w", err)
364 df, err := getDictField(v.Type(), keyStr)
366 return fmt.Errorf("parsing bencode dict into %v: %w", v.Type(), err)
369 // now we need to actually parse it
371 // Discard the value, there's nowhere to put it.
373 if_, ok = d.parseValueInterface()
375 return fmt.Errorf("error parsing value for key %q", keyStr)
378 return fmt.Errorf("missing value for key %q", keyStr)
382 setValue := reflect.New(df.Type).Elem()
383 // log.Printf("parsing into %v", setValue.Type())
384 ok, err = d.parseValue(setValue)
386 var target *UnmarshalTypeError
387 if !(errors.As(err, &target) && df.Tags.IgnoreUnmarshalTypeError()) {
388 return fmt.Errorf("parsing value for key %q: %w", keyStr, err)
392 return fmt.Errorf("missing value for key %q", keyStr)
398 func (d *Decoder) parseList(v reflect.Value) error {
401 // If the list is a singleton of the expected type, use that value. See
402 // https://github.com/anacrolix/torrent/issues/297.
403 l := reflect.New(reflect.SliceOf(v.Type()))
404 if err := d.parseList(l.Elem()); err != nil {
407 if l.Elem().Len() != 1 {
408 return &UnmarshalTypeError{
409 BencodeTypeName: "list",
410 UnmarshalTargetType: v.Type(),
413 v.Set(l.Elem().Index(0))
415 case reflect.Array, reflect.Slice:
416 // We can work with this. Normal case, fallthrough.
421 if v.Kind() == reflect.Slice && i >= v.Len() {
422 v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
426 ok, err := d.parseValue(v.Index(i))
434 _, ok := d.parseValueInterface()
442 if v.Kind() == reflect.Array {
443 z := reflect.Zero(v.Type().Elem())
444 for n := v.Len(); i < n; i++ {
452 if i == 0 && v.Kind() == reflect.Slice {
453 v.Set(reflect.MakeSlice(v.Type(), 0, 0))
458 func (d *Decoder) readOneValue() bool {
459 b, err := d.r.ReadByte()
473 // read until there is nothing to read
474 for d.readOneValue() {
476 // consume 'e' as well
481 d.buf.WriteString("e")
483 if b >= '0' && b <= '9' {
484 start := d.buf.Len() - 1
486 length, err := strconv.ParseInt(bytesAsString(d.buf.Bytes()[start:]), 10, 64)
487 checkForIntParseError(err, d.Offset-1)
489 d.buf.WriteString(":")
490 n, err := io.CopyN(&d.buf, d.r, length)
493 checkForUnexpectedEOF(err, d.Offset)
496 What: errors.New("unexpected I/O error: " + err.Error()),
502 d.raiseUnknownValueType(b, d.Offset-1)
508 func (d *Decoder) parseUnmarshaler(v reflect.Value) bool {
509 if !v.Type().Implements(unmarshalerType) {
510 if v.Addr().Type().Implements(unmarshalerType) {
517 if !d.readOneValue() {
520 m := v.Interface().(Unmarshaler)
521 err := m.UnmarshalBencode(d.buf.Bytes())
523 panic(&UnmarshalerError{v.Type(), err})
528 // Returns true if there was a value and it's now stored in 'v', otherwise
529 // there was an end symbol ("e") and no value was stored.
530 func (d *Decoder) parseValue(v reflect.Value) (bool, error) {
531 // we support one level of indirection at the moment
532 if v.Kind() == reflect.Ptr {
533 // if the pointer is nil, allocate a new element of the type it
536 v.Set(reflect.New(v.Type().Elem()))
541 if d.parseUnmarshaler(v) {
545 // common case: interface{}
546 if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
547 iface, _ := d.parseValueInterface()
548 v.Set(reflect.ValueOf(iface))
552 b, err := d.r.ReadByte()
562 return true, d.parseDict(v)
564 return true, d.parseList(v)
566 return true, d.parseInt(v)
568 if b >= '0' && b <= '9' {
571 // Write the first digit of the length to the buffer.
573 return true, d.parseString(v)
576 d.raiseUnknownValueType(b, d.Offset-1)
581 // An unknown bencode type character was encountered.
582 func (d *Decoder) raiseUnknownValueType(b byte, offset int64) {
585 What: fmt.Errorf("unknown value type %+q", b),
589 func (d *Decoder) parseValueInterface() (interface{}, bool) {
590 b, err := d.r.ReadByte()
600 return d.parseDictInterface(), true
602 return d.parseListInterface(), true
604 return d.parseIntInterface(), true
606 if b >= '0' && b <= '9' {
608 // append first digit of the length to the buffer
610 return d.parseStringInterface(), true
613 d.raiseUnknownValueType(b, d.Offset-1)
618 // Called after 'i', for an arbitrary integer size.
619 func (d *Decoder) parseIntInterface() (ret interface{}) {
620 start := d.Offset - 1
622 if err := d.readInt(); err != nil {
625 n, err := strconv.ParseInt(d.buf.String(), 10, 64)
626 if ne, ok := err.(*strconv.NumError); ok && ne.Err == strconv.ErrRange {
628 _, ok := i.SetString(d.buf.String(), 10)
632 What: errors.New("failed to parse integer"),
637 checkForIntParseError(err, start)
645 func (d *Decoder) readBytes(length int) []byte {
646 b, err := io.ReadAll(io.LimitReader(d.r, int64(length)))
650 if len(b) != length {
651 panic(fmt.Errorf("read %v bytes expected %v", len(b), length))
656 func (d *Decoder) parseStringInterface() string {
657 length, err := d.parseStringLength()
661 b := d.readBytes(int(length))
662 d.Offset += int64(len(b))
664 panic(&SyntaxError{Offset: d.Offset, What: err})
666 return bytesAsString(b)
669 func (d *Decoder) parseDictInterface() interface{} {
670 dict := make(map[string]interface{})
674 keyi, ok := d.parseValueInterface()
679 key, ok := keyi.(string)
683 What: errors.New("non-string key in a dict"),
687 d.throwSyntaxError(start, fmt.Errorf("dict keys unsorted: %q <= %q", key, lastKey))
690 valuei, ok := d.parseValueInterface()
692 d.throwSyntaxError(start, fmt.Errorf("dict elem missing value [key=%v]", key))
701 func (d *Decoder) parseListInterface() (list []interface{}) {
702 list = []interface{}{}
703 valuei, ok := d.parseValueInterface()
705 list = append(list, valuei)
706 valuei, ok = d.parseValueInterface()