110 lines
2.1 KiB
Go
110 lines
2.1 KiB
Go
package torrent
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import (
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"crypto"
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"errors"
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"fmt"
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"math/rand"
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"sync"
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"time"
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"bitbucket.org/anacrolix/go.torrent/peer_protocol"
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)
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const (
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pieceHash = crypto.SHA1
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maxRequests = 250 // Maximum pending requests we allow peers to send us.
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chunkSize = 0x4000 // 16KiB
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BEP20 = "-GT0000-" // Peer ID client identifier prefix
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nominalDialTimeout = time.Second * 30
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minDialTimeout = 5 * time.Second
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)
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type (
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InfoHash [20]byte
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pieceSum [20]byte
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)
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func (ih *InfoHash) AsString() string {
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return string(ih[:])
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}
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func (ih *InfoHash) HexString() string {
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return fmt.Sprintf("%x", ih[:])
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}
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type piecePriority byte
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const (
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piecePriorityNone piecePriority = iota
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piecePriorityNormal
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piecePriorityReadahead
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piecePriorityNext
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piecePriorityNow
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)
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type piece struct {
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Hash pieceSum
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PendingChunkSpecs map[chunkSpec]struct{}
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Hashing bool
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QueuedForHash bool
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EverHashed bool
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Event sync.Cond
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Priority piecePriority
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}
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func (p *piece) shuffledPendingChunkSpecs() (css []chunkSpec) {
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if len(p.PendingChunkSpecs) == 0 {
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return
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}
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css = make([]chunkSpec, 0, len(p.PendingChunkSpecs))
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for cs := range p.PendingChunkSpecs {
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css = append(css, cs)
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}
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if len(css) <= 1 {
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return
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}
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for i := range css {
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j := rand.Intn(i + 1)
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css[i], css[j] = css[j], css[i]
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}
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return
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}
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func (p *piece) Complete() bool {
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return len(p.PendingChunkSpecs) == 0 && p.EverHashed
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}
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func lastChunkSpec(pieceLength peer_protocol.Integer) (cs chunkSpec) {
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cs.Begin = (pieceLength - 1) / chunkSize * chunkSize
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cs.Length = pieceLength - cs.Begin
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return
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}
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type chunkSpec struct {
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Begin, Length peer_protocol.Integer
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}
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type request struct {
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Index peer_protocol.Integer
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chunkSpec
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}
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func newRequest(index, begin, length peer_protocol.Integer) request {
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return request{index, chunkSpec{begin, length}}
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}
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var (
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// Requested data not yet available.
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ErrDataNotReady = errors.New("data not ready")
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)
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// The size in bytes of a metadata extension piece.
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func metadataPieceSize(totalSize int, piece int) int {
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ret := totalSize - piece*(1<<14)
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if ret > 1<<14 {
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ret = 1 << 14
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}
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return ret
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}
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