1032 lines
20 KiB
Go
1032 lines
20 KiB
Go
package dht
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import (
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"crypto"
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_ "crypto/sha1"
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"log"
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"math/big"
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"net"
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"os"
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"sync"
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"time"
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"bitbucket.org/anacrolix/go.torrent/logonce"
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"bitbucket.org/anacrolix/go.torrent/util"
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"github.com/anacrolix/libtorgo/bencode"
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)
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type Server struct {
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id string
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socket net.PacketConn
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transactions []*transaction
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transactionIDInt uint64
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nodes map[string]*Node // Keyed by dHTAddr.String().
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mu sync.Mutex
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closed chan struct{}
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NumConfirmedAnnounces int
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}
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type dHTAddr interface {
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net.Addr
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}
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func newDHTAddr(addr *net.UDPAddr) (ret dHTAddr) {
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ret = addr
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return
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}
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type ServerConfig struct {
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Addr string
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Conn net.PacketConn
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}
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func (s *Server) LocalAddr() net.Addr {
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return s.socket.LocalAddr()
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}
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func makeSocket(addr string) (socket *net.UDPConn, err error) {
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addr_, err := net.ResolveUDPAddr("", addr)
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if err != nil {
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return
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}
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socket, err = net.ListenUDP("udp", addr_)
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return
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}
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func NewServer(c *ServerConfig) (s *Server, err error) {
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if c == nil {
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c = &ServerConfig{}
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}
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s = &Server{}
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if c.Conn != nil {
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s.socket = c.Conn
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} else {
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s.socket, err = makeSocket(c.Addr)
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if err != nil {
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return
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}
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}
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err = s.init()
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if err != nil {
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return
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}
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go func() {
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err := s.serve()
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select {
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case <-s.closed:
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return
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default:
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}
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if err != nil {
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panic(err)
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}
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}()
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go func() {
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err := s.bootstrap()
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if err != nil {
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panic(err)
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}
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}()
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return
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}
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func (s *Server) String() string {
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return fmt.Sprintf("dht server on %s", s.socket.LocalAddr())
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}
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type Node struct {
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addr dHTAddr
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id string
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lastHeardFrom time.Time
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lastSentTo time.Time
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announceToken string
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}
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func (n *Node) NodeInfo() (ret NodeInfo) {
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ret.Addr = n.addr
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if n := copy(ret.ID[:], n.id); n != 20 {
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panic(n)
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}
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return
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}
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func (n *Node) Good() bool {
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if len(n.id) != 20 {
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return false
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}
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if n.lastSentTo.IsZero() {
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return true
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}
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if n.lastSentTo.Before(n.lastHeardFrom) {
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return true
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}
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if time.Now().Sub(n.lastHeardFrom) >= 1*time.Minute {
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return false
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}
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return true
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}
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type Msg map[string]interface{}
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var _ fmt.Stringer = Msg{}
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func (m Msg) String() string {
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return fmt.Sprintf("%#v", m)
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}
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func (m Msg) T() (t string) {
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tif, ok := m["t"]
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if !ok {
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return
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}
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t, _ = tif.(string)
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return
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}
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func (m Msg) Nodes() []NodeInfo {
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var r findNodeResponse
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if err := r.UnmarshalKRPCMsg(m); err != nil {
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return nil
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}
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return r.Nodes
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}
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type KRPCError struct {
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Code int
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Msg string
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}
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func (me KRPCError) Error() string {
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return fmt.Sprintf("KRPC error %d: %s", me.Code, me.Msg)
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}
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var _ error = KRPCError{}
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func (m Msg) Error() (ret *KRPCError) {
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if m["y"] != "e" {
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return
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}
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ret = &KRPCError{}
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switch e := m["e"].(type) {
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case []interface{}:
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ret.Code = int(e[0].(int64))
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ret.Msg = e[1].(string)
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case string:
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ret.Msg = e
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default:
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logonce.Stderr.Printf(`KRPC error "e" value has unexpected type: %T`, e)
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}
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return
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}
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// Returns the token given in response to a get_peers request for future
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// announce_peer requests to that node.
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func (m Msg) AnnounceToken() string {
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defer func() { recover() }()
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return m["r"].(map[string]interface{})["token"].(string)
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}
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type transaction struct {
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mu sync.Mutex
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remoteAddr dHTAddr
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t string
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Response chan Msg
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onResponse func(Msg)
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done chan struct{}
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}
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func (t *transaction) timeout() {
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t.Close()
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}
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func (t *transaction) closing() bool {
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select {
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case <-t.done:
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return true
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default:
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return false
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}
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}
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func (t *transaction) Close() {
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t.mu.Lock()
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defer t.mu.Unlock()
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if t.closing() {
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return
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}
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close(t.Response)
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close(t.done)
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}
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func (t *transaction) handleResponse(m Msg) {
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t.mu.Lock()
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if t.closing() {
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t.mu.Unlock()
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return
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}
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close(t.done)
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t.mu.Unlock()
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if t.onResponse != nil {
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t.onResponse(m)
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}
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select {
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case t.Response <- m:
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default:
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panic("blocked handling response")
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}
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close(t.Response)
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}
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func (s *Server) setDefaults() (err error) {
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if s.id == "" {
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var id [20]byte
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h := crypto.SHA1.New()
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ss, err := os.Hostname()
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if err != nil {
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log.Print(err)
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}
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ss += s.socket.LocalAddr().String()
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h.Write([]byte(ss))
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if b := h.Sum(id[:0:20]); len(b) != 20 {
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panic(len(b))
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}
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if len(id) != 20 {
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panic(len(id))
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}
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s.id = string(id[:])
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}
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s.nodes = make(map[string]*Node, 10000)
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return
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}
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func (s *Server) init() (err error) {
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err = s.setDefaults()
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if err != nil {
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return
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}
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s.closed = make(chan struct{})
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return
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}
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func (s *Server) processPacket(b []byte, addr dHTAddr) {
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var d Msg
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err := bencode.Unmarshal(b, &d)
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if err != nil {
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if se, ok := err.(*bencode.SyntaxError); !ok || se.Offset != 0 {
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log.Printf("%s: received bad krpc message: %s: %q", s, err, b)
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}
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return
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}
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s.mu.Lock()
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defer s.mu.Unlock()
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if d["y"] == "q" {
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s.handleQuery(addr, d)
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return
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}
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t := s.findResponseTransaction(d.T(), addr)
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if t == nil {
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//log.Printf("unexpected message: %#v", d)
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return
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}
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t.handleResponse(d)
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s.removeTransaction(t)
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id := ""
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if d["y"] == "r" {
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id = d["r"].(map[string]interface{})["id"].(string)
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}
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s.heardFromNode(addr, id)
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}
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func (s *Server) serve() error {
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for {
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var b [0x10000]byte
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n, addr, err := s.socket.ReadFrom(b[:])
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if err != nil {
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return err
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}
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s.processPacket(b[:n], newDHTAddr(addr.(*net.UDPAddr)))
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}
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}
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func (s *Server) AddNode(ni NodeInfo) {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.nodes == nil {
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s.nodes = make(map[string]*Node)
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}
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n := s.getNode(ni.Addr)
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if n.id == "" {
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n.id = string(ni.ID[:])
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}
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}
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func (s *Server) nodeByID(id string) *Node {
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for _, node := range s.nodes {
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if node.id == id {
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return node
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}
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}
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return nil
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}
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func (s *Server) handleQuery(source dHTAddr, m Msg) {
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args := m["a"].(map[string]interface{})
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s.heardFromNode(source, args["id"].(string))
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switch m["q"] {
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case "ping":
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s.reply(source, m["t"].(string), nil)
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case "get_peers":
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targetID := args["info_hash"].(string)
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var rNodes []NodeInfo
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// TODO: Reply with "values" list if we have peers instead.
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for _, node := range s.closestGoodNodes(8, targetID) {
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rNodes = append(rNodes, node.NodeInfo())
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}
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nodesBytes := make([]byte, CompactNodeInfoLen*len(rNodes))
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for i, ni := range rNodes {
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err := ni.PutCompact(nodesBytes[i*CompactNodeInfoLen : (i+1)*CompactNodeInfoLen])
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if err != nil {
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panic(err)
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}
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}
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s.reply(source, m["t"].(string), map[string]interface{}{
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"nodes": string(nodesBytes),
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"token": "hi",
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})
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case "find_node":
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targetID := args["target"].(string)
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if len(targetID) != 20 {
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log.Printf("bad DHT query: %v", m)
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return
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}
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var rNodes []NodeInfo
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if node := s.nodeByID(targetID); node != nil {
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rNodes = append(rNodes, node.NodeInfo())
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} else {
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for _, node := range s.closestGoodNodes(8, targetID) {
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rNodes = append(rNodes, node.NodeInfo())
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}
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}
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nodesBytes := make([]byte, CompactNodeInfoLen*len(rNodes))
|
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for i, ni := range rNodes {
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err := ni.PutCompact(nodesBytes[i*CompactNodeInfoLen : (i+1)*CompactNodeInfoLen])
|
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if err != nil {
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panic(err)
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}
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}
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s.reply(source, m["t"].(string), map[string]interface{}{
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"nodes": string(nodesBytes),
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})
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case "announce_peer":
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// TODO(anacrolix): Implement this lolz.
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// log.Print(m)
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case "vote":
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// TODO(anacrolix): Or reject, I don't think I want this.
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default:
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log.Printf("%s: not handling received query: q=%s", s, m["q"])
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return
|
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}
|
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}
|
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func (s *Server) reply(addr dHTAddr, t string, r map[string]interface{}) {
|
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if r == nil {
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r = make(map[string]interface{}, 1)
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}
|
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r["id"] = s.IDString()
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m := map[string]interface{}{
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"t": t,
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"y": "r",
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"r": r,
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}
|
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b, err := bencode.Marshal(m)
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if err != nil {
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panic(err)
|
|
}
|
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err = s.writeToNode(b, addr)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
}
|
|
|
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func (s *Server) heardFromNode(addr dHTAddr, id string) {
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n := s.getNode(addr)
|
|
if len(id) == 20 {
|
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n.id = id
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}
|
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n.lastHeardFrom = time.Now()
|
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}
|
|
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func (s *Server) getNode(addr dHTAddr) (n *Node) {
|
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if util.AddrPort(addr) == 0 {
|
|
panic(addr)
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}
|
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n = s.nodes[addr.String()]
|
|
if n == nil {
|
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n = &Node{
|
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addr: addr,
|
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}
|
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s.nodes[addr.String()] = n
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) writeToNode(b []byte, node dHTAddr) (err error) {
|
|
n, err := s.socket.WriteTo(b, node)
|
|
if err != nil {
|
|
err = fmt.Errorf("error writing %d bytes to %s: %s", len(b), node, err)
|
|
return
|
|
}
|
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if n != len(b) {
|
|
err = io.ErrShortWrite
|
|
return
|
|
}
|
|
s.sentToNode(node)
|
|
return
|
|
}
|
|
|
|
func (s *Server) sentToNode(addr dHTAddr) {
|
|
n := s.getNode(addr)
|
|
n.lastSentTo = time.Now()
|
|
}
|
|
|
|
func (s *Server) findResponseTransaction(transactionID string, sourceNode dHTAddr) *transaction {
|
|
for _, t := range s.transactions {
|
|
if t.t == transactionID && t.remoteAddr.String() == sourceNode.String() {
|
|
return t
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (s *Server) nextTransactionID() string {
|
|
var b [binary.MaxVarintLen64]byte
|
|
n := binary.PutUvarint(b[:], s.transactionIDInt)
|
|
s.transactionIDInt++
|
|
return string(b[:n])
|
|
}
|
|
|
|
func (s *Server) removeTransaction(t *transaction) {
|
|
for i, tt := range s.transactions {
|
|
if t == tt {
|
|
last := len(s.transactions) - 1
|
|
s.transactions[i] = s.transactions[last]
|
|
s.transactions = s.transactions[:last]
|
|
return
|
|
}
|
|
}
|
|
panic("transaction not found")
|
|
}
|
|
|
|
func (s *Server) addTransaction(t *transaction) {
|
|
s.transactions = append(s.transactions, t)
|
|
}
|
|
|
|
func (s *Server) IDString() string {
|
|
if len(s.id) != 20 {
|
|
panic("bad node id")
|
|
}
|
|
return s.id
|
|
}
|
|
|
|
func (s *Server) timeoutTransaction(t *transaction) {
|
|
select {
|
|
case <-t.done:
|
|
return
|
|
case <-time.After(time.Minute):
|
|
}
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
select {
|
|
case <-t.done:
|
|
return
|
|
default:
|
|
}
|
|
t.timeout()
|
|
s.removeTransaction(t)
|
|
}
|
|
|
|
func (s *Server) query(node dHTAddr, q string, a map[string]interface{}) (t *transaction, err error) {
|
|
tid := s.nextTransactionID()
|
|
if a == nil {
|
|
a = make(map[string]interface{}, 1)
|
|
}
|
|
a["id"] = s.IDString()
|
|
d := map[string]interface{}{
|
|
"t": tid,
|
|
"y": "q",
|
|
"q": q,
|
|
"a": a,
|
|
}
|
|
b, err := bencode.Marshal(d)
|
|
if err != nil {
|
|
return
|
|
}
|
|
t = &transaction{
|
|
remoteAddr: node,
|
|
t: tid,
|
|
Response: make(chan Msg, 1),
|
|
done: make(chan struct{}),
|
|
}
|
|
s.addTransaction(t)
|
|
err = s.writeToNode(b, node)
|
|
if err != nil {
|
|
s.removeTransaction(t)
|
|
return
|
|
}
|
|
go s.timeoutTransaction(t)
|
|
return
|
|
}
|
|
|
|
const CompactNodeInfoLen = 26
|
|
|
|
type NodeInfo struct {
|
|
ID [20]byte
|
|
Addr dHTAddr
|
|
}
|
|
|
|
func (ni *NodeInfo) PutCompact(b []byte) error {
|
|
if n := copy(b[:], ni.ID[:]); n != 20 {
|
|
panic(n)
|
|
}
|
|
ip := util.AddrIP(ni.Addr).To4()
|
|
if len(ip) != 4 {
|
|
panic(ip)
|
|
}
|
|
if n := copy(b[20:], ip); n != 4 {
|
|
panic(n)
|
|
}
|
|
binary.BigEndian.PutUint16(b[24:], uint16(util.AddrPort(ni.Addr)))
|
|
return nil
|
|
}
|
|
|
|
func (cni *NodeInfo) UnmarshalCompact(b []byte) error {
|
|
if len(b) != 26 {
|
|
return errors.New("expected 26 bytes")
|
|
}
|
|
if 20 != copy(cni.ID[:], b[:20]) {
|
|
panic("impossibru!")
|
|
}
|
|
cni.Addr = newDHTAddr(&net.UDPAddr{
|
|
IP: net.IPv4(b[20], b[21], b[22], b[23]),
|
|
Port: int(binary.BigEndian.Uint16(b[24:26])),
|
|
})
|
|
return nil
|
|
}
|
|
|
|
func (s *Server) Ping(node *net.UDPAddr) (*transaction, error) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
return s.query(newDHTAddr(node), "ping", nil)
|
|
}
|
|
|
|
// Announce a local peer. This can only be done to nodes that gave us an
|
|
// announce token, which is received in responses during GetPeers. It's
|
|
// recommended then that GetPeers is called before this method.
|
|
func (s *Server) AnnouncePeer(port int, impliedPort bool, infoHash string) (err error) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
for _, node := range s.closestNodes(160, infoHash, func(n *Node) bool {
|
|
return n.Good() && n.announceToken != ""
|
|
}) {
|
|
err = s.announcePeer(node.addr, infoHash, port, node.announceToken, impliedPort)
|
|
if err != nil {
|
|
break
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) announcePeer(node dHTAddr, infoHash string, port int, token string, impliedPort bool) error {
|
|
t, err := s.query(node, "announce_peer", map[string]interface{}{
|
|
"implied_port": func() int {
|
|
if impliedPort {
|
|
return 1
|
|
} else {
|
|
return 0
|
|
}
|
|
}(),
|
|
"info_hash": infoHash,
|
|
"port": port,
|
|
"token": token,
|
|
})
|
|
t.setOnResponse(func(m Msg) {
|
|
if err := m.Error(); err != nil {
|
|
logonce.Stderr.Printf("announce_peer response: %s", err)
|
|
return
|
|
}
|
|
s.NumConfirmedAnnounces++
|
|
})
|
|
return err
|
|
}
|
|
|
|
type findNodeResponse struct {
|
|
Nodes []NodeInfo
|
|
}
|
|
|
|
func getResponseNodes(m Msg) (s string, err error) {
|
|
defer func() {
|
|
r := recover()
|
|
if r == nil {
|
|
return
|
|
}
|
|
err = fmt.Errorf("couldn't get response nodes: %s: %#v", r, m)
|
|
}()
|
|
s = m["r"].(map[string]interface{})["nodes"].(string)
|
|
return
|
|
}
|
|
|
|
func (me *findNodeResponse) UnmarshalKRPCMsg(m Msg) error {
|
|
b, err := getResponseNodes(m)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
for i := 0; i < len(b); i += 26 {
|
|
var n NodeInfo
|
|
err := n.UnmarshalCompact([]byte(b[i : i+26]))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
me.Nodes = append(me.Nodes, n)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (t *transaction) setOnResponse(f func(m Msg)) {
|
|
if t.onResponse != nil {
|
|
panic(t.onResponse)
|
|
}
|
|
t.onResponse = f
|
|
}
|
|
|
|
func unmarshalNodeInfoBinary(b []byte) (ret []NodeInfo, err error) {
|
|
if len(b)%26 != 0 {
|
|
err = errors.New("bad buffer length")
|
|
return
|
|
}
|
|
ret = make([]NodeInfo, 0, len(b)/26)
|
|
for i := 0; i < len(b); i += 26 {
|
|
var ni NodeInfo
|
|
err = ni.UnmarshalCompact(b[i : i+26])
|
|
if err != nil {
|
|
return
|
|
}
|
|
ret = append(ret, ni)
|
|
}
|
|
return
|
|
}
|
|
|
|
func extractNodes(d Msg) (nodes []NodeInfo, err error) {
|
|
if d["y"] != "r" {
|
|
return
|
|
}
|
|
r, ok := d["r"]
|
|
if !ok {
|
|
err = errors.New("missing r dict")
|
|
return
|
|
}
|
|
rd, ok := r.(map[string]interface{})
|
|
if !ok {
|
|
err = errors.New("bad r value type")
|
|
return
|
|
}
|
|
n, ok := rd["nodes"]
|
|
if !ok {
|
|
return
|
|
}
|
|
ns, ok := n.(string)
|
|
if !ok {
|
|
err = errors.New("bad nodes value type")
|
|
return
|
|
}
|
|
return unmarshalNodeInfoBinary([]byte(ns))
|
|
}
|
|
|
|
func (s *Server) liftNodes(d Msg) {
|
|
if d["y"] != "r" {
|
|
return
|
|
}
|
|
var r findNodeResponse
|
|
err := r.UnmarshalKRPCMsg(d)
|
|
if err != nil {
|
|
// log.Print(err)
|
|
} else {
|
|
for _, cni := range r.Nodes {
|
|
if util.AddrPort(cni.Addr) == 0 {
|
|
// TODO: Why would people even do this?
|
|
continue
|
|
}
|
|
n := s.getNode(cni.Addr)
|
|
n.id = string(cni.ID[:])
|
|
}
|
|
// log.Printf("lifted %d nodes", len(r.Nodes))
|
|
}
|
|
}
|
|
|
|
// Sends a find_node query to addr. targetID is the node we're looking for.
|
|
func (s *Server) findNode(addr dHTAddr, targetID string) (t *transaction, err error) {
|
|
t, err = s.query(addr, "find_node", map[string]interface{}{"target": targetID})
|
|
if err != nil {
|
|
return
|
|
}
|
|
// Scrape peers from the response to put in the server's table before
|
|
// handing the response back to the caller.
|
|
t.setOnResponse(func(d Msg) {
|
|
s.liftNodes(d)
|
|
})
|
|
return
|
|
}
|
|
|
|
func extractValues(m Msg) (vs []util.CompactPeer) {
|
|
r, ok := m["r"]
|
|
if !ok {
|
|
return
|
|
}
|
|
rd, ok := r.(map[string]interface{})
|
|
if !ok {
|
|
return
|
|
}
|
|
v, ok := rd["values"]
|
|
if !ok {
|
|
return
|
|
}
|
|
vl, ok := v.([]interface{})
|
|
if !ok {
|
|
panic(v)
|
|
}
|
|
vs = make([]util.CompactPeer, 0, len(vl))
|
|
for _, i := range vl {
|
|
s, ok := i.(string)
|
|
if !ok {
|
|
panic(i)
|
|
}
|
|
var cp util.CompactPeer
|
|
err := cp.UnmarshalBinary([]byte(s))
|
|
if err != nil {
|
|
log.Printf("error decoding values list element: %s", err)
|
|
continue
|
|
}
|
|
vs = append(vs, cp)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) getPeers(addr dHTAddr, infoHash string) (t *transaction, err error) {
|
|
if len(infoHash) != 20 {
|
|
err = fmt.Errorf("infohash has bad length")
|
|
return
|
|
}
|
|
t, err = s.query(addr, "get_peers", map[string]interface{}{"info_hash": infoHash})
|
|
if err != nil {
|
|
return
|
|
}
|
|
t.setOnResponse(func(m Msg) {
|
|
s.liftNodes(m)
|
|
s.getNode(addr).announceToken = m.AnnounceToken()
|
|
})
|
|
return
|
|
}
|
|
|
|
func bootstrapAddr() (net.Addr, error) {
|
|
return net.ResolveUDPAddr("udp4", "router.bittorrent.com:6881")
|
|
}
|
|
|
|
func (s *Server) addRootNode() error {
|
|
addr, err := net.ResolveUDPAddr("udp4", "router.bittorrent.com:6881")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
s.nodes[addr.String()] = &Node{
|
|
addr: newDHTAddr(addr),
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Populates the node table.
|
|
func (s *Server) bootstrap() (err error) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
if len(s.nodes) == 0 {
|
|
err = s.addRootNode()
|
|
}
|
|
if err != nil {
|
|
return
|
|
}
|
|
for {
|
|
var outstanding sync.WaitGroup
|
|
for _, node := range s.nodes {
|
|
var t *transaction
|
|
t, err = s.findNode(node.addr, s.id)
|
|
if err != nil {
|
|
return
|
|
}
|
|
outstanding.Add(1)
|
|
go func() {
|
|
<-t.Response
|
|
outstanding.Done()
|
|
}()
|
|
}
|
|
noOutstanding := make(chan struct{})
|
|
go func() {
|
|
outstanding.Wait()
|
|
close(noOutstanding)
|
|
}()
|
|
s.mu.Unlock()
|
|
select {
|
|
case <-s.closed:
|
|
s.mu.Lock()
|
|
return
|
|
case <-time.After(15 * time.Second):
|
|
case <-noOutstanding:
|
|
}
|
|
s.mu.Lock()
|
|
// log.Printf("now have %d nodes", len(s.nodes))
|
|
if s.numGoodNodes() >= 160 {
|
|
break
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) numGoodNodes() (num int) {
|
|
for _, n := range s.nodes {
|
|
if n.Good() {
|
|
num++
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) NumNodes() int {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
return len(s.nodes)
|
|
}
|
|
|
|
func (s *Server) Nodes() (nis []NodeInfo) {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
for _, node := range s.nodes {
|
|
// if !node.Good() {
|
|
// continue
|
|
// }
|
|
ni := NodeInfo{
|
|
Addr: node.addr,
|
|
}
|
|
if n := copy(ni.ID[:], node.id); n != 20 && n != 0 {
|
|
panic(n)
|
|
}
|
|
nis = append(nis, ni)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *Server) Close() {
|
|
s.mu.Lock()
|
|
select {
|
|
case <-s.closed:
|
|
default:
|
|
close(s.closed)
|
|
s.socket.Close()
|
|
}
|
|
s.mu.Unlock()
|
|
}
|
|
|
|
type distance interface {
|
|
Cmp(distance) int
|
|
BitCount() int
|
|
IsZero() bool
|
|
}
|
|
|
|
type bigIntDistance struct {
|
|
*big.Int
|
|
}
|
|
|
|
// How many bits?
|
|
func bitCount(n *big.Int) int {
|
|
var count int = 0
|
|
for _, b := range n.Bytes() {
|
|
count += int(bitCounts[b])
|
|
}
|
|
return count
|
|
}
|
|
|
|
// The bit counts for each byte value (0 - 255).
|
|
var bitCounts = []int8{
|
|
// Generated by Java BitCount of all values from 0 to 255
|
|
0, 1, 1, 2, 1, 2, 2, 3,
|
|
1, 2, 2, 3, 2, 3, 3, 4,
|
|
1, 2, 2, 3, 2, 3, 3, 4,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
1, 2, 2, 3, 2, 3, 3, 4,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
1, 2, 2, 3, 2, 3, 3, 4,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
4, 5, 5, 6, 5, 6, 6, 7,
|
|
1, 2, 2, 3, 2, 3, 3, 4,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
4, 5, 5, 6, 5, 6, 6, 7,
|
|
2, 3, 3, 4, 3, 4, 4, 5,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
4, 5, 5, 6, 5, 6, 6, 7,
|
|
3, 4, 4, 5, 4, 5, 5, 6,
|
|
4, 5, 5, 6, 5, 6, 6, 7,
|
|
4, 5, 5, 6, 5, 6, 6, 7,
|
|
5, 6, 6, 7, 6, 7, 7, 8,
|
|
}
|
|
|
|
func (me bigIntDistance) BitCount() int {
|
|
return bitCount(me.Int)
|
|
}
|
|
|
|
func (me bigIntDistance) Cmp(d distance) int {
|
|
return me.Int.Cmp(d.(bigIntDistance).Int)
|
|
}
|
|
|
|
func (me bigIntDistance) IsZero() bool {
|
|
return me.Int.Cmp(big.NewInt(0)) == 0
|
|
}
|
|
|
|
type bitCountDistance int
|
|
|
|
func (me bitCountDistance) BitCount() int { return int(me) }
|
|
|
|
func (me bitCountDistance) Cmp(rhs distance) int {
|
|
rhs_ := rhs.(bitCountDistance)
|
|
if me < rhs_ {
|
|
return -1
|
|
} else if me == rhs_ {
|
|
return 0
|
|
} else {
|
|
return 1
|
|
}
|
|
}
|
|
|
|
func (me bitCountDistance) IsZero() bool {
|
|
return me == 0
|
|
}
|
|
|
|
func idDistance(a, b string) distance {
|
|
if true {
|
|
if len(a) != 20 {
|
|
panic(a)
|
|
}
|
|
if len(b) != 20 {
|
|
panic(b)
|
|
}
|
|
x := new(big.Int)
|
|
y := new(big.Int)
|
|
x.SetBytes([]byte(a))
|
|
y.SetBytes([]byte(b))
|
|
dist := new(big.Int)
|
|
return bigIntDistance{dist.Xor(x, y)}
|
|
} else {
|
|
ret := 0
|
|
for i := 0; i < 20; i++ {
|
|
for j := uint(0); j < 8; j++ {
|
|
ret += int(a[i]>>j&1 ^ b[i]>>j&1)
|
|
}
|
|
}
|
|
return bitCountDistance(ret)
|
|
}
|
|
}
|
|
|
|
func (s *Server) closestGoodNodes(k int, targetID string) []*Node {
|
|
return s.closestNodes(k, targetID, func(n *Node) bool { return n.Good() })
|
|
}
|
|
|
|
func (s *Server) closestNodes(k int, targetID string, filter func(*Node) bool) []*Node {
|
|
sel := newKClosestNodesSelector(k, targetID)
|
|
idNodes := make(map[string]*Node, len(s.nodes))
|
|
for _, node := range s.nodes {
|
|
if !filter(node) {
|
|
continue
|
|
}
|
|
sel.Push(node.id)
|
|
idNodes[node.id] = node
|
|
}
|
|
ids := sel.IDs()
|
|
ret := make([]*Node, 0, len(ids))
|
|
for _, id := range ids {
|
|
ret = append(ret, idNodes[id])
|
|
}
|
|
return ret
|
|
}
|