97 lines
2.8 KiB
Go
97 lines
2.8 KiB
Go
// Copyright 2015 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 udp
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import (
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"bytes"
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"encoding/binary"
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"time"
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"github.com/chihaya/chihaya/tracker/models"
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)
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// Writer implements the tracker.Writer interface for the UDP protocol.
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type Writer struct {
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buf *bytes.Buffer
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connectionID []byte
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transactionID []byte
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}
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// WriteError writes the failure reason as a null-terminated string.
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func (w *Writer) WriteError(err error) error {
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w.writeHeader(errorActionID)
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w.buf.WriteString(err.Error())
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w.buf.WriteRune('\000')
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return nil
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}
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// WriteAnnounce encodes an announce response by selecting the proper announce
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// format based on the BitTorrent spec.
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func (w *Writer) WriteAnnounce(resp *models.AnnounceResponse) (err error) {
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if resp.Announce.HasIPv6() {
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err = w.WriteAnnounceIPv6(resp)
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} else {
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err = w.WriteAnnounceIPv4(resp)
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}
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return
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}
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// WriteAnnounceIPv6 encodes an announce response according to BEP45.
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func (w *Writer) WriteAnnounceIPv6(resp *models.AnnounceResponse) error {
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w.writeHeader(announceDualStackActionID)
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Interval/time.Second))
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Incomplete))
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Complete))
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binary.Write(w.buf, binary.BigEndian, uint32(len(resp.IPv4Peers)))
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binary.Write(w.buf, binary.BigEndian, uint32(len(resp.IPv6Peers)))
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for _, peer := range resp.IPv4Peers {
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w.buf.Write(peer.IP)
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binary.Write(w.buf, binary.BigEndian, peer.Port)
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}
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for _, peer := range resp.IPv6Peers {
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w.buf.Write(peer.IP)
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binary.Write(w.buf, binary.BigEndian, peer.Port)
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}
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return nil
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}
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// WriteAnnounceIPv4 encodes an announce response according to BEP15.
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func (w *Writer) WriteAnnounceIPv4(resp *models.AnnounceResponse) error {
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w.writeHeader(announceActionID)
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Interval/time.Second))
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Incomplete))
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binary.Write(w.buf, binary.BigEndian, uint32(resp.Complete))
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for _, peer := range resp.IPv4Peers {
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w.buf.Write(peer.IP)
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binary.Write(w.buf, binary.BigEndian, peer.Port)
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}
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return nil
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}
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// WriteScrape encodes a scrape response according to BEP15.
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func (w *Writer) WriteScrape(resp *models.ScrapeResponse) error {
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w.writeHeader(scrapeActionID)
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for _, torrent := range resp.Files {
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binary.Write(w.buf, binary.BigEndian, uint32(torrent.Seeders.Len()))
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binary.Write(w.buf, binary.BigEndian, uint32(torrent.Snatches))
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binary.Write(w.buf, binary.BigEndian, uint32(torrent.Leechers.Len()))
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}
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return nil
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}
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// writeHeader writes the action and transaction ID to the response.
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func (w *Writer) writeHeader(action uint32) {
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binary.Write(w.buf, binary.BigEndian, action)
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w.buf.Write(w.transactionID)
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}
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