mirror of
https://github.com/go-i2p/go-i2p-bt.git
synced 2025-07-13 03:53:00 -04:00
290 lines
6.8 KiB
Go
290 lines
6.8 KiB
Go
// Copyright 2020 xgfone
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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 udptracker
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"net"
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"strings"
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"sync/atomic"
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"time"
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"github.com/xgfone/bt/metainfo"
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)
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// NewTrackerClientByDial returns a new TrackerClient by dialing.
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func NewTrackerClientByDial(network, address string, c ...TrackerClientConfig) (
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*TrackerClient, error) {
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conn, err := net.Dial(network, address)
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if err != nil {
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return nil, err
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}
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return NewTrackerClient(conn.(*net.UDPConn), c...), nil
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}
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// NewTrackerClient returns a new TrackerClient.
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func NewTrackerClient(conn *net.UDPConn, c ...TrackerClientConfig) *TrackerClient {
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var conf TrackerClientConfig
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conf.set(c...)
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ipv4 := strings.Contains(conn.LocalAddr().String(), ".")
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return &TrackerClient{conn: conn, conf: conf, ipv4: ipv4}
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}
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// TrackerClientConfig is used to configure the TrackerClient.
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type TrackerClientConfig struct {
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// ReadTimeout is used to receive the response.
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ReadTimeout time.Duration // Default: 5s
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MaxBufSize int // Default: 2048
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}
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func (c *TrackerClientConfig) set(conf ...TrackerClientConfig) {
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if len(conf) > 0 {
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*c = conf[0]
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}
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if c.MaxBufSize <= 0 {
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c.MaxBufSize = 2048
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}
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if c.ReadTimeout <= 0 {
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c.ReadTimeout = time.Second * 5
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}
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}
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// TrackerClient is a tracker client based on UDP.
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//
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// Notice: the request is synchronized, that's, the last request is not returned,
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// the next request must not be sent.
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//
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// BEP 15
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type TrackerClient struct {
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ipv4 bool
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conf TrackerClientConfig
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conn *net.UDPConn
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last time.Time
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cid uint64
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tid uint32
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}
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// Close closes the UDP tracker client.
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func (utc *TrackerClient) Close() { utc.conn.Close() }
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func (utc *TrackerClient) readResp(b []byte) (int, error) {
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utc.conn.SetReadDeadline(time.Now().Add(utc.conf.ReadTimeout))
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return utc.conn.Read(b)
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}
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func (utc *TrackerClient) getTranID() uint32 {
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return atomic.AddUint32(&utc.tid, 1)
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}
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func (utc *TrackerClient) parseError(b []byte) (tid uint32, reason string) {
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tid = binary.BigEndian.Uint32(b[:4])
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reason = string(b[4:])
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return
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}
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func (utc *TrackerClient) send(b []byte) (err error) {
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n, err := utc.conn.Write(b)
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if err == nil && n < len(b) {
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err = io.ErrShortWrite
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}
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return
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}
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func (utc *TrackerClient) connect() (err error) {
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tid := utc.getTranID()
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buf := bytes.NewBuffer(make([]byte, 0, 16))
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binary.Write(buf, binary.BigEndian, ProtocolID)
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binary.Write(buf, binary.BigEndian, ActionConnect)
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binary.Write(buf, binary.BigEndian, tid)
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if err = utc.send(buf.Bytes()); err != nil {
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return
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}
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data := make([]byte, 32)
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n, err := utc.readResp(data)
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if err != nil {
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return
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} else if n < 8 {
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return io.ErrShortBuffer
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}
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data = data[:n]
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switch binary.BigEndian.Uint32(data[:4]) {
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case ActionConnect:
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case ActionError:
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_, reason := utc.parseError(data[4:])
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return errors.New(reason)
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default:
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return errors.New("tracker response not connect action")
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}
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if n < 16 {
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return io.ErrShortBuffer
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}
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if binary.BigEndian.Uint32(data[4:8]) != tid {
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return errors.New("invalid transaction id")
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}
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utc.cid = binary.BigEndian.Uint64(data[8:16])
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utc.last = time.Now()
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return
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}
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func (utc *TrackerClient) getConnectionID() (cid uint64, err error) {
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cid = utc.cid
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if time.Now().Sub(utc.last) > time.Minute {
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if err = utc.connect(); err == nil {
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cid = utc.cid
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}
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}
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return
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}
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func (utc *TrackerClient) announce(req AnnounceRequest) (r AnnounceResponse, err error) {
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cid, err := utc.getConnectionID()
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if err != nil {
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return
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}
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tid := utc.getTranID()
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buf := bytes.NewBuffer(make([]byte, 0, 110))
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binary.Write(buf, binary.BigEndian, cid)
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binary.Write(buf, binary.BigEndian, ActionAnnounce)
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binary.Write(buf, binary.BigEndian, tid)
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req.EncodeTo(buf)
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b := buf.Bytes()
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if err = utc.send(b); err != nil {
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return
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}
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data := make([]byte, utc.conf.MaxBufSize)
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n, err := utc.readResp(data)
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if err != nil {
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return
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} else if n < 8 {
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err = io.ErrShortBuffer
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return
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}
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data = data[:n]
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switch binary.BigEndian.Uint32(data[:4]) {
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case ActionAnnounce:
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case ActionError:
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_, reason := utc.parseError(data[4:])
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err = errors.New(reason)
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return
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default:
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err = errors.New("tracker response not connect action")
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return
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}
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if n < 16 {
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err = io.ErrShortBuffer
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return
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}
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if binary.BigEndian.Uint32(data[4:8]) != tid {
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err = errors.New("invalid transaction id")
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return
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}
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r.DecodeFrom(data[8:], utc.ipv4)
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return
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}
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// Announce sends a Announce request to the tracker.
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//
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// Notice:
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// 1. if it does not connect to the UDP tracker server, it will connect to it,
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// then send the ANNOUNCE request.
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// 2. If returning an error, you should retry it.
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// See http://www.bittorrent.org/beps/bep_0015.html#time-outs
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func (utc *TrackerClient) Announce(r AnnounceRequest) (AnnounceResponse, error) {
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return utc.announce(r)
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}
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func (utc *TrackerClient) scrape(infohashes []metainfo.Hash) (rs []ScrapeResponse, err error) {
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cid, err := utc.getConnectionID()
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if err != nil {
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return
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}
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tid := utc.getTranID()
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buf := bytes.NewBuffer(make([]byte, 0, 16+len(infohashes)*20))
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binary.Write(buf, binary.BigEndian, cid)
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binary.Write(buf, binary.BigEndian, ActionScrape)
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binary.Write(buf, binary.BigEndian, tid)
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for _, h := range infohashes {
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buf.Write(h[:])
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}
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if err = utc.send(buf.Bytes()); err != nil {
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return
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}
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data := make([]byte, utc.conf.MaxBufSize)
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n, err := utc.readResp(data)
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if err != nil {
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return
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} else if n < 8 {
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err = io.ErrShortBuffer
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return
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}
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data = data[:n]
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switch binary.BigEndian.Uint32(data[:4]) {
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case ActionScrape:
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case ActionError:
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_, reason := utc.parseError(data[4:])
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err = errors.New(reason)
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return
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default:
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err = errors.New("tracker response not connect action")
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return
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}
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if binary.BigEndian.Uint32(data[4:8]) != tid {
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err = errors.New("invalid transaction id")
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return
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}
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data = data[8:]
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_len := len(data)
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rs = make([]ScrapeResponse, 0, _len/12)
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for i := 12; i <= _len; i += 12 {
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var r ScrapeResponse
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r.DecodeFrom(data[i-12 : i])
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rs = append(rs, r)
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}
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return
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}
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// Scrape sends a Scrape request to the tracker.
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//
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// Notice:
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// 1. if it does not connect to the UDP tracker server, it will connect to it,
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// then send the ANNOUNCE request.
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// 2. If returning an error, you should retry it.
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// See http://www.bittorrent.org/beps/bep_0015.html#time-outs
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func (utc *TrackerClient) Scrape(hs []metainfo.Hash) ([]ScrapeResponse, error) {
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return utc.scrape(hs)
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}
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