105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
// Copyright 2013 The Chihaya Authors. All rights reserved.
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// Use of this source code is governed by the BSD 2-Clause license,
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// which can be found in the LICENSE file.
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// Package bencode implements bencoding of objects as defined in BEP 3 using
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// type assertion rather than the use of reflection.
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package bencode
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import (
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"bytes"
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"errors"
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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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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{}) error {
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switch v := data.(type) {
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case Marshaler:
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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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if err != nil {
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return err
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}
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case string:
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fmt.Fprintf(w, "%d:%s", len(v), v)
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case int:
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fmt.Fprintf(w, "i%de", v)
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case uint:
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fmt.Fprintf(w, "i%se", strconv.FormatUint(uint64(v), 10))
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case int64:
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fmt.Fprintf(w, "i%se", strconv.FormatInt(v, 10))
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case uint64:
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fmt.Fprintf(w, "i%se", strconv.FormatUint(v, 10))
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case time.Duration: // Assume seconds
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fmt.Fprintf(w, "i%se", strconv.FormatInt(int64(v/time.Second), 10))
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case map[string]interface{}:
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fmt.Fprintf(w, "d")
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for key, val := range v {
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fmt.Fprintf(w, "%s:%s", strconv.Itoa(len(key)), key)
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err := marshal(w, val)
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if err != nil {
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return err
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}
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}
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case []string:
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fmt.Fprintf(w, "l")
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for _, val := range v {
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err := marshal(w, val)
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if err != nil {
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return err
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}
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}
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fmt.Fprintf(w, "e")
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default:
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// Although not currently necessary,
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// should handle []interface{} manually; Go can't do it implicitly
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return errors.New("bencode: attempted to marshal unsupported type")
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}
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return nil
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}
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