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main.go
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main.go
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package main
import(
"fmt"
"crypto/sha1"
"math/rand"
"io"
"time"
"math"
"sync/atomic"
"net"
"os"
"runtime"
"log"
"github.com/zeebo/bencode"
"bytes"
"errors"
"encoding/hex"
)
//好友节点,带你进入DHT网络
var BOOTSTRAP []string = []string {
"67.215.246.10:6881", //router.bittorrent.com
"91.121.59.153:6881", //dht.transmissionbt.com
"82.221.103.244:6881",//router.utorrent.com
"212.129.33.50:6881"}
type Id []byte
//节点的Id与网络地址信息
type NodeInfo struct {
Ip net.IP
Port int
Id Id
lastseen time.Time
}
//DHT网络节点
type KNode struct {
node *NodeInfo
routing *Routing
network *Network
log *log.Logger
krpc *KRPC
outChan chan string
}
type Network struct {
dhtNode *KNode
Conn *net.UDPConn
}
type KRPC struct {
dhtNode *KNode
tid uint32
}
//路由表,每个表又分文桶(Bucket)
type Routing struct {
selfNode *KNode
table []*Bucket
}
//k桶,Bucket
type Bucket struct {
Nodes []*NodeInfo
lastchange time.Time //新鲜度
}
type KRPCMSG struct {
T string
Y string
Args interface{}
addr *net.UDPAddr
}
type Query struct {
Q string
A map[string]interface{}
}
type Response struct {
R map[string]interface{}
}
//计数
var nums int = 0
func main(){
cpus := runtime.NumCPU()
runtime.GOMAXPROCS(cpus)
master := make(chan string)
for i := 0; i < cpus; i++ {
go Executing(cpus, master)
}
OutHash(master)
}
func OutHash(master chan string){
for {
select {
case infohash := <-master:
fmt.Println(infohash)
nums++
fmt.Println(nums)
}
}
}
func Executing(cpus int, master chan string ){
dhtNode := NewdhtNode(master, os.Stdout)
dhtNode.Run()
}
//生成节点id
func GenerateId() Id {
random := rand.New(rand.NewSource(time.Now().UnixNano()))
h := sha1.New()
io.WriteString(h, time.Now().String())
io.WriteString(h, string(random.Int()))
return h.Sum(nil)
}
//DhtNode 节点信息
func NewdhtNode(master chan string, logger io.Writer) *KNode{
dhtNode := new(KNode)
dhtNode.log = log.New(logger, "", log.Ldate|log.Ltime|log.Lmicroseconds|log.Lshortfile)
dhtNode.node = NewNode()
dhtNode.routing = NewRouting(dhtNode)
dhtNode.network = NewNetwork(dhtNode)
dhtNode.krpc = NewKrpc(dhtNode)
dhtNode.outChan = master
return dhtNode
}
func NewNode() *NodeInfo {
node := new(NodeInfo)
id := GenerateId()
node.Id = id
return node
}
//如果将NewBucket写为一个函数,最后分别赋值table[0]与table[1]那么两个table的节点数量将相同,这是一个坑!
func NewRouting(dhtNode *KNode) *Routing {
routing := new(Routing)
routing.selfNode = dhtNode
bucket1 := NewBucket()
bucket2 := NewBucket2()
routing.table = make([]*Bucket, 2)
routing.table[0] = bucket1
routing.table[1] = bucket2
return routing
}
func NewBucket() *Bucket {
b := new(Bucket)
b.Nodes = nil
b.lastchange = time.Now()
return b
}
func NewBucket2() *Bucket {
b := new(Bucket)
b.Nodes = nil
b.lastchange = time.Now()
return b
}
func (bucket *Bucket) Len() int {
return len(bucket.Nodes)
}
//节点Ip,Port,Id
func NewNetwork(dhtNode *KNode) *Network {
network := new(Network)
network.dhtNode = dhtNode
addr := new(net.UDPAddr)
var err error
network.Conn, err = net.ListenUDP("udp", addr)
if err != nil {
panic(err)
}
laddr := network.Conn.LocalAddr().(*net.UDPAddr)
network.dhtNode.node.Ip = laddr.IP
network.dhtNode.node.Port = laddr.Port
return network
}
//KRPC协议
func NewKrpc(dhtNode *KNode) *KRPC {
krpc := new(KRPC)
krpc.dhtNode = dhtNode
return krpc
}
func (dhtNode *KNode) Run(){
dhtNode.log.Println(fmt.Sprintf("Current Node ID is %s ", dhtNode.node.Id))
dhtNode.log.Println(fmt.Sprintf("DhtBT %s is runing...", dhtNode.network.Conn.LocalAddr().String()))
go func() { dhtNode.network.GetInfohash()}()
go func() { dhtNode.FindNode()}()
}
func (dhtNode *KNode) FindNode() {
for {
if dhtNode.routing.table[0].Len() == 0{
dhtNode.searchNodes(dhtNode.node.Id)
} else {
for _, node := range dhtNode.routing.table[0].Nodes {
t := time.Now()
d, _ := time.ParseDuration("-10s")
last := t.Add(d)
ok := node.lastseen.Before(last)
if ok {
continue
}
dhtNode.GoFindNode( node, GenerateId())
}
dhtNode.routing.table[0].Nodes = nil
time.Sleep(1 * time.Second)
}
}
}
func (dhtNode *KNode) searchNodes(target Id) {
for _, host := range BOOTSTRAP {
addr, err := net.ResolveUDPAddr("udp", host)
if err != nil {
dhtNode.log.Fatalf("Resolve DNS error, %s\n", err)
return
}
node := new(NodeInfo)
node.Port = addr.Port
node.Ip = addr.IP
dhtNode.GoFindNode(node, target)
}
}
func (table *Bucket) Add(n *NodeInfo) {
table.Nodes = append(table.Nodes, n)
table.Updatetime(n)
}
func (bucket *Bucket) Updatetime(n *NodeInfo ) {
bucket.lastchange = time.Now()
n.lastseen = time.Now()
}
func (routing *Routing) InsertNode(other *NodeInfo) {
if routing.isSelf(other) {
return
}
if routing.table[1].Len() < 8 {
routing.table[1].Add(other)
}
routing.table[0].Add(other)
}
func (routing *Routing) isSelf(other *NodeInfo) bool {
return (routing.selfNode.node.Id.CompareTo(other.Id) == 0)
}
func (id Id) CompareTo(other Id) int {
s1 := id.HexString()
s2 := other.HexString()
if s1 > s2 {
return 1
} else if s1 == s2 {
return 0
} else {
return -1
}
}
func (id *Id) HexString() string {
return fmt.Sprintf("%x", id)
}
func (dhtNode *KNode) GoFindNode(info *NodeInfo, target Id){
if info.Ip.Equal(net.IPv4(0, 0, 0, 0)) || info.Port == 0 {
return
}
addr := new(net.UDPAddr)
addr.IP = info.Ip
addr.Port = info.Port
data, err := dhtNode.krpc.EncodingFindNode(target)
if err != nil {
dhtNode.log.Println(err)
return
}
err = dhtNode.network.Send([]byte(data), addr)
if err != nil {
dhtNode.log.Println(err)
return
}
}
func (krpc *KRPC) EncodingFindNode(target Id) (string, error) {
tid := krpc.GenTID()
v := make(map[string]interface{})
v["t"] = fmt.Sprintf("%d", tid)
v["y"] = "q"
v["q"] = "find_node"
args := make(map[string]string)
args["id"] = string(krpc.dhtNode.node.Id)
args["target"] = string(target) //查找自己,找到离自己较近的节点
v["a"] = args
s, err := bencode.EncodeString(v)
if err != nil {
krpc.dhtNode.log.Fatalln(err)
}
return s, err
}
func (network *Network) Send(data []byte, addr *net.UDPAddr) error {
_, err := network.Conn.WriteToUDP(data, addr)
if err != nil {
network.dhtNode.log.Println( err)
}
return err
}
func (encode *KRPC) GenTID() uint32 {
return encode.autoID() % math.MaxUint16
}
func (encode *KRPC) autoID() uint32 {
return atomic.AddUint32(&encode.tid, 1)
}
//通过网络UDP包获取infohash
//Reads a UDP packet from network.Conn, copying the payload into b. It returns the number of bytes copied into b and the return address that was on the packet
func (network *Network) GetInfohash() {
b := make([]byte, 1000)
for {
_, addr, err := network.Conn.ReadFromUDP(b)
if err != nil {
continue
}
network.dhtNode.krpc.DecodePackage(string(b), addr)
}
}
func (krpc *KRPC) DecodePackage(data string, addr *net.UDPAddr) error {
val := make(map[string]interface{})
if err := bencode.DecodeString(data, &val); err != nil {
return err
} else {
var ok bool
msg := new(KRPCMSG)
msg.T, ok = val["t"].(string)
if !ok {
err = errors.New("Do not have transaction ID ")
return err
}
msg.Y, ok = val["y"].(string)
if !ok {
err = errors.New("Do know message type ")
return err
}
msg.addr = addr
switch msg.Y {
case "q":
query := new(Query)
query.Q = val["q"].(string)
query.A = val["a"].(map[string]interface{})
msg.Args = query
krpc.Query(msg)
case "r":
res := new(Response)
res.R = val["r"].(map[string]interface{})
msg.Args = res
krpc.Response(msg)
}
return nil
}
}
//table[1]不知从哪在自动增加节点数量,远远超过8,待解决
func (krpc *KRPC) Query(msg *KRPCMSG) {
if query, ok := msg.Args.(*Query); ok {
queryNode := new(NodeInfo)
queryNode.Ip = msg.addr.IP
queryNode.Port = msg.addr.Port
queryNode.Id = Id(query.A["id"].(string))
switch query.Q {
case "find_node":
closeNodes := krpc.dhtNode.routing.table[1].Nodes
nodes := ConvertByteStream(closeNodes)
data, _ := krpc.EncodingNodeResult(msg.T, "", nodes)
krpc.dhtNode.network.Send([]byte(data), msg.addr)
case "announce_peer":
if infohash, ok := query.A["info_hash"].(string); ok {
krpc.dhtNode.outChan <- Id(infohash).String()
}
case "get_peers":
if infohash, ok := query.A["info_hash"].(string); ok {
krpc.dhtNode.outChan <- Id(infohash).String()
token := krpc.dhtNode.GenToken(queryNode)
nodes := ConvertByteStream(krpc.dhtNode.routing.table[1].Nodes)
data, _ := krpc.EncodingNodeResult(msg.T, token, nodes)
krpc.dhtNode.network.Send([]byte(data), msg.addr)
}
}
krpc.dhtNode.routing.InsertNode(queryNode)
}
}
func (dhtNode *KNode) GenToken(sender *NodeInfo) string {
h := sha1.New()
io.WriteString(h, sender.Ip.String())
io.WriteString(h, time.Now().String())
token := bytes.NewBuffer(h.Sum(nil)).String()
return token
}
func ConvertByteStream(nodes []*NodeInfo) []byte {
buf := bytes.NewBuffer(nil)
for _, v := range nodes {
convertNodeInfo(buf, v)
}
return buf.Bytes()
}
func convertNodeInfo(buf *bytes.Buffer, v *NodeInfo) {
buf.Write(v.Id)
convertIPPort(buf, v.Ip, v.Port)
}
func convertIPPort(buf *bytes.Buffer, ip net.IP, port int) {
buf.Write(ip.To4())
buf.WriteByte(byte((port & 0xFF00) >> 8))
buf.WriteByte(byte(port & 0xFF))
}
func (krpc *KRPC) EncodingNodeResult(tid string, token string, nodes []byte) (string, error) {
v := make(map[string]interface{})
v["t"] = tid
v["y"] = "r"
args := make(map[string]string)
args["id"] = krpc.dhtNode.node.Id.String()
if token != "" {
args["token"] = token
}
args["nodes"] = bytes.NewBuffer(nodes).String()
v["r"] = args
s, err := bencode.EncodeString(v)
return s, err
}
func (id Id) String() string {
return hex.EncodeToString(id)
}
func (krpc *KRPC) Response(msg *KRPCMSG) {
if res, ok := msg.Args.(*Response); ok {
if nodestr, ok := res.R["nodes"].(string); ok {
nodes := ParseBytesStream([]byte(nodestr))
for _, v := range nodes {
krpc.dhtNode.routing.InsertNode(v)
}
}
}
}
func ParseBytesStream(data []byte) []*NodeInfo {
var nodes []*NodeInfo = nil
for j := 0; j < len(data); j = j + 26 {
if j+26 > len(data) {
break
}
kn := data[j : j+26]
node := new(NodeInfo)
node.Id = Id(kn[0:20])
node.Ip = kn[20:24]
port := kn[24:26]
node.Port = int(port[0])<<8 + int(port[1])
nodes = append(nodes, node)
}
return nodes
}