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rpc.go
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rpc.go
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package DHTCrawl
import (
"bytes"
"errors"
"github.com/zeebo/bencode"
"net"
// "reflect"
)
const (
TYPE_QUERY = "q"
TYPE_RESPONSE = "r"
TYPE_ERROR = "e"
OP_FIND_NODE = "find_node"
OP_PING = "ping"
OP_GET_PEERS = "get_peers"
OP_ANNOUNCE_PEER = "announce_peer"
)
type (
Result struct {
Cmd string
Hash Hash
ID NodeID
UDPAddr *net.UDPAddr
TCPAddr *net.TCPAddr
Token string
Nodes []*Node
Tid string
}
RPC struct {
}
)
//query
func PacketFindNode(id, target NodeID) []byte {
d := map[string]interface{}{
"t": GenerateTid(),
"y": TYPE_QUERY,
"q": OP_FIND_NODE,
"a": map[string]string{
"id": id.String(),
"target": target.String(),
},
}
b, _ := bencode.EncodeBytes(d)
return b
}
//response
//id is self id
func PacketGetPeers(hash Hash, id NodeID, self NodeID, nodes []byte, token, tid string) []byte {
d := map[string]interface{}{
"t": tid,
"y": TYPE_RESPONSE,
"r": map[string]string{
"id": id.Neighbor(self).String(),
"nodes": bytes.NewBuffer(nodes).String(),
"token": token,
},
}
b, _ := bencode.EncodeBytes(d)
return b
}
func PacketAnnucePeer(hash Hash, id NodeID, self NodeID, tid string) []byte {
d := map[string]interface{}{
"t": tid,
"y": TYPE_RESPONSE,
"r": map[string]string{"id": NodeID(id).Neighbor(self).String()},
}
b, _ := bencode.EncodeBytes(d)
return b
}
func PacketPong(id NodeID, self NodeID, tid string) []byte {
d := map[string]interface{}{
"t": tid,
"y": TYPE_RESPONSE,
"r": map[string]string{"id": id.Neighbor(self).String()},
}
b, _ := bencode.EncodeBytes(d)
return b
}
func NewRPC() *RPC {
return &RPC{}
}
func (r *RPC) HandleGetPeers(args map[string]interface{}) (hash Hash, id NodeID) {
if h, ok := args["info_hash"].(string); ok {
hash = Hash(h)
}
if i, ok := args["id"].(string); ok {
id = NodeID(i)
}
return
}
//info hash, tcp port, token
func (r *RPC) HandleAnnoucePeer(args map[string]interface{}) (hash Hash, id NodeID, port int64, token string) {
if h, ok := args["info_hash"].(string); ok {
hash = Hash(h)
}
if i, ok := args["id"].(string); ok {
id = NodeID(i)
}
port, _ = args["port"].(int64)
token, _ = args["token"].(string)
//if implied_port not equal 0, then use same udp port for tcp
if implied, ok := args["implied_port"].(int64); ok && implied != int64(0) {
port = int64(-1)
}
return
}
func (r *RPC) HandleFindNode(resp map[string]interface{}) (ns []*Node) {
if b, ok := resp["nodes"].(string); ok {
if nodes, err := DecodeNodes([]byte(b)); err == nil {
for _, node := range nodes {
ns = append(ns, node)
}
}
}
return
}
func (r *RPC) handlePing(args map[string]interface{}) NodeID {
if id, ok := args["id"].(string); ok {
return NodeID([]byte(id))
}
return nil
}
func (r *RPC) parse(data []byte, addr *net.UDPAddr) (*Result, error) {
v := make(map[string]interface{})
if err := bencode.DecodeBytes(data, &v); err != nil {
return nil, err
}
t, ok := v["t"].(string)
if !ok {
return nil, errors.New("Invalid protocol field 't'")
}
y, ok := v["y"].(string)
if !ok {
return nil, errors.New("Invalid protocol field 'y'")
}
switch y {
case TYPE_QUERY:
q, ok := v["q"].(string)
if !ok {
return nil, errors.New("Invalid protocol field 'q'")
}
a, ok := v["a"].(map[string]interface{})
if !ok {
return nil, errors.New("Invalid protocol field 'a'")
}
switch q {
case OP_GET_PEERS:
hash, id := r.HandleGetPeers(a)
if string(hash) != "" && string(id) != "" {
return &Result{Cmd: OP_GET_PEERS, UDPAddr: addr, Hash: hash, ID: id, Tid: t}, nil
}
case OP_ANNOUNCE_PEER:
hash, id, port, token := r.HandleAnnoucePeer(a)
if port == int64(-1) {
port = int64(addr.Port)
}
if string(hash) != "" && IsValidPort(int(port)) && string(id) != "" {
tcpAddr := &net.TCPAddr{IP: addr.IP, Port: int(port)}
return &Result{
Cmd: OP_ANNOUNCE_PEER,
UDPAddr: addr,
Hash: hash,
ID: id,
TCPAddr: tcpAddr,
Token: token,
Tid: t,
}, nil
}
case OP_PING:
if id := r.handlePing(a); id != nil {
return &Result{
Cmd: OP_PING,
UDPAddr: addr,
Tid: t,
ID: id,
}, nil
}
default:
}
case TYPE_RESPONSE:
//only has find_node response
if a, ok := v["r"].(map[string]interface{}); ok {
return &Result{Cmd: OP_FIND_NODE, Nodes: r.HandleFindNode(a), Tid: t}, nil
}
case TYPE_ERROR:
default:
}
return nil, errors.New("Invalid protocol")
}