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package dht
import (
"net"
"strconv"
"time"
"github.com/felix/dhtsearch/bencode"
"github.com/felix/logger"
)
var (
routers = []string{
"router.bittorrent.com:6881",
"dht.transmissionbt.com:6881",
"router.utorrent.com:6881",
"dht.aelitis.com:6881",
}
)
// Node joins the DHT network
type Node struct {
id Infohash
address string
port int
conn *net.UDPConn
pool chan chan packet
rTable *routingTable
workers []*dhtWorker
udpTimeout int
packetsOut chan packet
peersOut chan Peer
closing chan chan error
log logger.Logger
//table routingTable
// OnAnnoucePeer is called for each peer that announces itself
OnAnnoucePeer func(p *Peer)
}
// NewNode creates a new DHT node
func NewNode(opts ...Option) (n *Node, err error) {
id := randomInfoHash()
n = &Node{
id: id,
address: "0.0.0.0",
port: 6881,
rTable: newRoutingTable(id),
workers: make([]*dhtWorker, 1),
closing: make(chan chan error),
log: logger.New(&logger.Options{Name: "dht"}),
peersOut: make(chan Peer),
}
// Set variadic options passed
for _, option := range opts {
err = option(n)
if err != nil {
return nil, err
}
}
return n, nil
}
// Close stuff
func (n *Node) Close() error {
n.log.Warn("node closing")
errCh := make(chan error)
n.closing <- errCh
// Signal workers
for _, w := range n.workers {
w.stop()
}
return <-errCh
}
// Run starts the node on the DHT
func (n *Node) Run() chan Peer {
listener, err := net.ListenPacket("udp4", n.address+":"+strconv.Itoa(n.port))
if err != nil {
n.log.Error("failed to listen", "error", err)
return nil
}
n.conn = listener.(*net.UDPConn)
n.port = n.conn.LocalAddr().(*net.UDPAddr).Port
n.log.Info("listening", "id", n.id, "address", n.address, "port", n.port)
// Worker pool
n.pool = make(chan chan packet)
// Packets onto the network
n.packetsOut = make(chan packet, 512)
// Create a slab for allocation
byteSlab := newSlab(8192, 10)
// Start our workers
n.log.Debug("starting workers", "count", len(n.workers))
for i := 0; i < len(n.workers); i++ {
w := &dhtWorker{
pool: n.pool,
packetsOut: n.packetsOut,
peersOut: n.peersOut,
rTable: n.rTable,
quit: make(chan struct{}),
log: n.log.Named("worker"),
}
go w.run()
n.workers[i] = w
}
n.log.Debug("starting packet writer")
// Start writing packets from channel to DHT
go func() {
var p packet
for {
select {
case p = <-n.packetsOut:
//n.conn.SetWriteDeadline(time.Now().Add(time.Second * time.Duration(n.udpTimeout)))
_, err := n.conn.WriteToUDP(p.data, &p.raddr)
if err != nil {
// TODO remove from routing or add to blacklist?
n.log.Warn("failed to write packet", "error", err)
}
}
}
}()
n.log.Debug("starting packet reader")
// Start reading packets
go func() {
n.bootstrap()
// TODO configurable
ticker := time.Tick(10 * time.Second)
// Send packets from conn to workers
for {
select {
case errCh := <-n.closing:
// TODO
errCh <- nil
case pCh := <-n.pool:
go func() {
b := byteSlab.Alloc()
c, addr, err := n.conn.ReadFromUDP(b)
if err != nil {
n.log.Warn("UDP read error", "error", err)
return
}
// Chop and send
pCh <- packet{
data: b[0:c],
raddr: *addr,
}
byteSlab.Free(b)
}()
case <-ticker:
go func() {
if n.rTable.isEmpty() {
n.bootstrap()
} else {
n.makeNeighbours()
}
}()
}
}
}()
return n.peersOut
}
func (n *Node) bootstrap() {
n.log.Debug("bootstrapping")
for _, s := range routers {
addr, err := net.ResolveUDPAddr("udp4", s)
if err != nil {
n.log.Error("failed to parse bootstrap address", "error", err)
return
}
rn := &remoteNode{address: *addr}
n.findNode(rn, n.id)
}
}
func (n *Node) makeNeighbours() {
n.log.Debug("making neighbours")
for _, rn := range n.rTable.getNodes() {
n.findNode(rn, n.id)
}
n.rTable.refresh()
}
func (n Node) findNode(rn *remoteNode, id Infohash) {
target := randomInfoHash()
n.sendMsg(rn, "find_node", map[string]interface{}{
"id": string(id),
"target": string(target),
})
}
// ping sends ping query to the chan.
func (n *Node) ping(rn *remoteNode) {
id := n.id.GenNeighbour(rn.id)
n.sendMsg(rn, "ping", map[string]interface{}{
"id": string(id),
})
}
func (n Node) sendMsg(rn *remoteNode, qType string, a map[string]interface{}) error {
// Stop if sending to self
if rn.id.Equal(n.id) {
return nil
}
t := newTransactionID()
//n.log.Debug("sending message", "type", qType, "remote", rn)
data := makeQuery(t, qType, a)
b, err := bencode.Encode(data)
if err != nil {
return err
}
n.packetsOut <- packet{
data: b,
raddr: rn.address,
}
return nil
}
|
