/
metadata.go
163 lines (133 loc) · 3.35 KB
/
metadata.go
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package main
import (
"bytes"
"crypto/sha1"
"log"
bencode "github.com/jackpal/bencode-go"
"github.com/rakoo/rakoshare/pkg/bitset"
)
type messagetype int
const (
METADATA_REQUEST messagetype = iota
METADATA_DATA
METADATA_REJECT
)
const (
METADATA_PIECE_SIZE = 1 << 14 // 16kiB
)
type MetadataMessage struct {
MsgType messagetype "msg_type"
Piece int "piece"
TotalSize int "total_size"
}
func (t *TorrentSession) DoMetadata(msg []byte, p *peerState) {
var message MetadataMessage
err := bencode.Unmarshal(bytes.NewReader(msg), &message)
if err != nil {
log.Println("Error when parsing metadata: ", err)
return
}
mt := message.MsgType
switch mt {
case METADATA_REQUEST:
if !t.si.HaveTorrent {
break
}
rawInfo := t.m.RawInfo()
from := message.Piece * METADATA_PIECE_SIZE
// Piece asked must be between the first one and the last one.
// Note that the last one will most of the time be smaller than
// METADATA_PIECE_SIZE
if from >= len(rawInfo) {
log.Printf("%d is out of range. Not sending this\n", message.Piece)
break
}
to := from + METADATA_PIECE_SIZE
if to > len(rawInfo) {
to = len(rawInfo)
}
if _, ok := p.theirExtensions["ut_metadata"]; !ok {
log.Println("%s doesn't understand ut_metadata\n", p.address)
break
}
respHeader := MetadataMessage{
MsgType: METADATA_DATA,
Piece: message.Piece,
TotalSize: len(rawInfo),
}
var resp bytes.Buffer
resp.WriteByte(EXTENSION)
resp.WriteByte(byte(p.theirExtensions["ut_metadata"]))
err = bencode.Marshal(&resp, respHeader)
if err != nil {
log.Println("Couldn't header metadata response: ", err)
break
}
resp.Write(rawInfo[from:to])
p.sendMessage(resp.Bytes())
case METADATA_DATA:
if t.si.HaveTorrent {
break
}
if message.TotalSize == 0 {
log.Println("No metadata size, bailing out")
return
}
if message.Piece >= len(t.si.ME.Pieces) {
log.Printf("Rejecting invalid metadata piece %d, max is %d\n",
message.Piece, len(t.si.ME.Pieces)-1)
break
}
pieceSize := METADATA_PIECE_SIZE
if message.Piece == len(t.si.ME.Pieces)-1 {
pieceSize = message.TotalSize - (message.TotalSize/METADATA_PIECE_SIZE)*METADATA_PIECE_SIZE
}
t.si.ME.Pieces[message.Piece] = msg[len(msg)-pieceSize:]
finished := true
for idx, data := range t.si.ME.Pieces {
if len(data) == 0 {
p.sendMetadataRequest(idx)
finished = false
break
}
}
if !finished {
break
}
log.Println("Finished downloading metadata!")
var full bytes.Buffer
for _, piece := range t.si.ME.Pieces {
full.Write(piece)
}
info := full.Bytes()
// Verify sha
sha := sha1.New()
sha.Write(info)
actual := string(sha.Sum(nil))
if actual != t.m.InfoHash {
log.Println("Invalid metadata")
log.Printf("Expected %x, got %x\n", t.m.InfoHash, actual)
break
}
err = t.reload(info)
if err != nil {
return
}
if p.have == nil {
if p.temporaryBitfield != nil {
p.have = bitset.NewFromBytes(t.totalPieces, p.temporaryBitfield)
p.temporaryBitfield = nil
} else {
p.have = bitset.New(t.totalPieces)
}
}
if p.have == nil {
log.Panic("Invalid bitfield data")
}
p.SendBitfield(t.pieceSet)
case METADATA_REJECT:
log.Printf("%d didn't want to send piece %d\n", p.address, message.Piece)
default:
log.Println("Didn't understand metadata extension type: ", mt)
}
}