189 lines
3.4 KiB
Go
189 lines
3.4 KiB
Go
package bencode
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import (
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"bytes"
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"fmt"
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"io"
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"strconv"
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"time"
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)
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// An Encoder writes bencoded objects to an output stream.
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type Encoder struct {
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w io.Writer
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}
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// NewEncoder returns a new encoder that writes to w.
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func NewEncoder(w io.Writer) *Encoder {
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return &Encoder{w: w}
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}
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// Encode writes the bencoding of v to the stream.
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func (enc *Encoder) Encode(v interface{}) error {
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return marshal(enc.w, v)
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}
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// Marshal returns the bencoding of v.
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func Marshal(v interface{}) ([]byte, error) {
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var buf bytes.Buffer
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err := marshal(&buf, v)
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return buf.Bytes(), err
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}
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// Marshaler is the interface implemented by objects that can marshal
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// themselves.
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type Marshaler interface {
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MarshalBencode() ([]byte, error)
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}
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// marshal writes types bencoded to an io.Writer.
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func marshal(w io.Writer, data interface{}) (err error) {
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switch v := data.(type) {
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case Marshaler:
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var bencoded []byte
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bencoded, err = v.MarshalBencode()
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if err != nil {
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return err
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}
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_, err = w.Write(bencoded)
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case []byte:
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err = marshalBytes(w, v)
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case string:
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err = marshalString(w, v)
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case []string:
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err = marshalStringSlice(w, v)
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case int:
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err = marshalInt(w, int64(v))
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case int16:
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err = marshalInt(w, int64(v))
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case int32:
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err = marshalInt(w, int64(v))
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case int64:
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err = marshalInt(w, int64(v))
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case uint:
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err = marshalUint(w, uint64(v))
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case uint16:
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err = marshalUint(w, uint64(v))
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case uint32:
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err = marshalUint(w, uint64(v))
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case uint64:
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err = marshalUint(w, uint64(v))
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case time.Duration: // Assume seconds
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err = marshalInt(w, int64(v/time.Second))
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case map[string]interface{}:
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err = marshalMap(w, v)
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case []interface{}:
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err = marshalList(w, v)
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default:
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return fmt.Errorf("attempted to marshal unsupported type:\n%T", v)
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}
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return err
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}
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func marshalInt(w io.Writer, v int64) error {
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if _, err := w.Write([]byte{'i'}); err != nil {
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return err
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}
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if _, err := w.Write([]byte(strconv.FormatInt(v, 10))); err != nil {
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return err
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}
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_, err := w.Write([]byte{'e'})
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return err
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}
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func marshalUint(w io.Writer, v uint64) error {
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if _, err := w.Write([]byte{'i'}); err != nil {
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return err
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}
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if _, err := w.Write([]byte(strconv.FormatUint(v, 10))); err != nil {
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return err
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}
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_, err := w.Write([]byte{'e'})
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return err
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}
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func marshalBytes(w io.Writer, v []byte) error {
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if _, err := w.Write([]byte(strconv.Itoa(len(v)))); err != nil {
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return err
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}
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if _, err := w.Write([]byte{':'}); err != nil {
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return err
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}
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_, err := w.Write(v)
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return err
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}
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func marshalString(w io.Writer, v string) error {
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return marshalBytes(w, []byte(v))
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}
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func marshalStringSlice(w io.Writer, v []string) error {
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if _, err := w.Write([]byte{'l'}); err != nil {
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return err
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}
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for _, val := range v {
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if err := marshal(w, val); err != nil {
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return err
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}
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}
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_, err := w.Write([]byte{'e'})
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return err
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}
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func marshalList(w io.Writer, v []interface{}) error {
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if _, err := w.Write([]byte{'l'}); err != nil {
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return err
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}
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for _, val := range v {
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if err := marshal(w, val); err != nil {
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return err
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}
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}
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_, err := w.Write([]byte{'e'})
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return err
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}
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func marshalMap(w io.Writer, v map[string]interface{}) error {
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if _, err := w.Write([]byte{'d'}); err != nil {
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return err
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}
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for key, val := range v {
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if err := marshalString(w, key); err != nil {
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return err
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}
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if err := marshal(w, val); err != nil {
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return err
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}
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}
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_, err := w.Write([]byte{'e'})
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return err
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}
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