173 lines
3.3 KiB
Go
173 lines
3.3 KiB
Go
// Copyright 2016 Jimmy Zelinskie
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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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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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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marshalString(w, v)
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case int:
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marshalInt(w, int64(v))
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case uint:
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marshalUint(w, uint64(v))
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case int16:
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marshalInt(w, int64(v))
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case uint16:
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marshalUint(w, uint64(v))
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case int32:
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marshalInt(w, int64(v))
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case uint32:
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marshalUint(w, uint64(v))
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case int64:
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marshalInt(w, v)
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case uint64:
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marshalUint(w, v)
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case []byte:
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marshalBytes(w, v)
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case time.Duration: // Assume seconds
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marshalInt(w, int64(v/time.Second))
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case Dict:
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marshal(w, map[string]interface{}(v))
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case []Dict:
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w.Write([]byte{'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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w.Write([]byte{'e'})
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case map[string]interface{}:
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w.Write([]byte{'d'})
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for key, val := range v {
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marshalString(w, 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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w.Write([]byte{'e'})
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case []string:
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w.Write([]byte{'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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w.Write([]byte{'e'})
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case List:
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marshal(w, []interface{}(v))
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case []interface{}:
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w.Write([]byte{'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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w.Write([]byte{'e'})
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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 nil
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}
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func marshalInt(w io.Writer, v int64) {
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w.Write([]byte{'i'})
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w.Write([]byte(strconv.FormatInt(v, 10)))
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w.Write([]byte{'e'})
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}
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func marshalUint(w io.Writer, v uint64) {
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w.Write([]byte{'i'})
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w.Write([]byte(strconv.FormatUint(v, 10)))
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w.Write([]byte{'e'})
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}
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func marshalBytes(w io.Writer, v []byte) {
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w.Write([]byte(strconv.Itoa(len(v))))
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w.Write([]byte{':'})
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w.Write(v)
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}
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func marshalString(w io.Writer, v string) {
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marshalBytes(w, []byte(v))
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}
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