Cannot use download subcmd to download what i seed torrent

[obitoquilt]

I want to announce the torrent to the dht network with the below code, but cannot use download subcmd to download magnet. Thanks for any advice.

package main

import (
	"fmt"
	"github.com/anacrolix/torrent"
	"github.com/anacrolix/torrent/bencode"
	"github.com/anacrolix/torrent/metainfo"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"time"
)

func main() {
	cfg := torrent.NewDefaultClientConfig()
	cfg.Seed = true
	cfg.Debug = true
	cfg.NoDefaultPortForwarding = true
	cfg.DisableIPv6 = true

	cl, err := torrent.NewClient(cfg)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%x\n", cl.PeerID())
	defer cl.Close()
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		cl.WriteStatus(w)
	})
	go http.ListenAndServe(":8080", nil)

	filePath := "testdata/docker.png"
	totalLength, err := totalLength(filePath)
	if err != nil {
		log.Fatal(err)
	}
	pieceLength := metainfo.ChoosePieceLength(totalLength)
	info := metainfo.Info{
		PieceLength: pieceLength,
	}
	err = info.BuildFromFilePath(filePath)
	if err != nil {
		log.Fatal(err)
	}
	for _, fi := range info.Files {
		log.Printf("added %q", fi.Path)
	}
	mi := &metainfo.MetaInfo{
		InfoBytes: bencode.MustMarshal(info),
	}
	torrentFile = mi
	torrentFile.Announce = ""

	// Add the torrent to the client
	tor, err := cl.AddTorrent(torrentFile)
	if err != nil {
		log.Fatal(err)
	}

	// Wait for the torrent to be ready
	<-tor.GotInfo()

	hash := tor.InfoHash()
	fmt.Printf("%v\n", tor.Metainfo().Magnet(&hash, tor.Info()))

	// Announce the torrent to DHT
	for _, _ds := range cl.DhtServers() {
		ds := _ds
		done, _, err := tor.AnnounceToDht(ds)
		if err != nil {
			log.Fatal(err)
		}
		for c := range done {
			fmt.Println("++++++++++++++++++++++++", c)
		}
	}
	select {}
}

[anacrolix]

The code looks good, but expecting a torrent to just work with a single seeder without knowing network conditions is iffy. You might try connecting your download cmds directly to the local seeding address. There's a lot of things that can go wrong trying to seed arbitrarily from a single node.

[obitoquilt]

Thanks for your reply. I follow your idea when connecting download cmds directly to the local seeding address(127.0.0.1:42069).

bargle.Subcommand{Name: "download", Command: func() bargle.Command {
	var dlc DownloadCmd
	dlc.TestPeer = []string{"127.0.0.1:42069"}  //  add here
	cmd := bargle.FromStruct(&dlc)
	cmd.DefaultAction = func() error {
		return downloadErr(downloadFlags{
			Debug:       debug,
			DownloadCmd: dlc,
		})
	}
	return cmd
}()}

And then, i run the seeder and leecher, but i encounter a error as shown below.

header obfuscation handshake: error while establishing secret: error reading Y: EOF

The Excuting function is:

c, err = doProtocolHandshakeOnDialResult(
    opts.t,
    obfuscatedHeaderFirst,
    addr,
    firstDialResult,
)

It is not clear if the code(add seeding address) is wrong or if some configuration is required.

[anacrolix]

Thanks for reporting this. The reason is that because you build the metainfo from the full file path, when you add the generated metainfo to your seeder client, it expects docker.png to be in the working directory. You can build the metainfo from testdata instead, or you can set the torrent storage to be operating from the testdata directory instead (pass a custom storage when you add the torrent).

Subsequently, the client thinks it doesn't have any data to seed, and rejects incoming connections because it both has no download priority set, and nothing to seed. If you make the above corrects, the leechers work.

[obitoquilt]

Thanks for your prompt reply. I try to pass a custom storage as shown below, but the code is stuck at <-tor.GotInfo().

filePath := "testdata/docker.png"

pc, err := storage.NewDefaultPieceCompletionForDir("testdata")
if err != nil {
	panic(err)
}
defer pc.Close()
tor, _ := cl.AddTorrentOpt(torrent.AddTorrentOpts{
	InfoHash: torrentFile.HashInfoBytes(),
	Storage: storage.NewFileOpts(storage.NewFileClientOpts{
		ClientBaseDir: "testdata",
		FilePathMaker: func(opts storage.FilePathMakerOpts) string {
			return filepath.Join(opts.File.Path...)
		},
		TorrentDirMaker: nil,
		PieceCompletion: pc,
	}),
})

// Wait for the torrent to be ready
<-tor.GotInfo()  // stuck here

hash := tor.InfoHash()
fmt.Printf("%v\n", tor.Metainfo().Magnet(&hash, tor.Info()))

[anacrolix]

I think you need to include the info bytes in AddTorrentOpt

[obitoquilt]

I think you need to include the info bytes in AddTorrentOpt

Thank you. I fix it but encounter same error as described above.
The seeder has a error: rejecting accepted conn: don't want conns right now.
The leechers has a error: error establishing outgoing connection to 127.0.0.1:42069: bittorrent protocol handshake: while reading: EOF.

I find that if remove rejectAccepted function, the error disapears. The leechers can find the torrent metainfo but file cannot be downloaded.

// client.go 524 lines
if !closed && conn != nil {
	reject = cl.rejectAccepted(conn) // if i remove this
}

I am very sorry to trouble you because i am not familiar with this.