syncthing/discover/cmd/discosrv/main.go
2014-04-03 23:40:10 +02:00

299 lines
5.4 KiB
Go

package main
import (
"encoding/binary"
"encoding/hex"
"flag"
"log"
"net"
"os"
"sync"
"time"
"github.com/calmh/syncthing/discover"
"github.com/golang/groupcache/lru"
"github.com/juju/ratelimit"
)
type Node struct {
Addresses []Address
Updated time.Time
}
type Address struct {
IP []byte
Port uint16
}
var (
nodes = make(map[string]Node)
lock sync.Mutex
queries = 0
answered = 0
limited = 0
debug = false
limiter = lru.New(1024)
)
func main() {
var listen string
var timestamp bool
flag.StringVar(&listen, "listen", ":22025", "Listen address")
flag.BoolVar(&debug, "debug", false, "Enable debug output")
flag.BoolVar(&timestamp, "timestamp", true, "Timestamp the log output")
flag.Parse()
log.SetOutput(os.Stdout)
if !timestamp {
log.SetFlags(0)
}
addr, _ := net.ResolveUDPAddr("udp", listen)
conn, err := net.ListenUDP("udp", addr)
if err != nil {
log.Fatal(err)
}
go logStats()
var buf = make([]byte, 1024)
for {
buf = buf[:cap(buf)]
n, addr, err := conn.ReadFromUDP(buf)
if limit(addr) {
// Rate limit in effect for source
continue
}
if err != nil {
log.Fatal(err)
}
if n < 4 {
log.Printf("Received short packet (%d bytes)", n)
continue
}
buf = buf[:n]
magic := binary.BigEndian.Uint32(buf)
switch magic {
case discover.AnnouncementMagicV1:
handleAnnounceV1(addr, buf)
case discover.QueryMagicV1:
handleQueryV1(conn, addr, buf)
case discover.AnnouncementMagicV2:
handleAnnounceV2(addr, buf)
case discover.QueryMagicV2:
handleQueryV2(conn, addr, buf)
}
}
}
func limit(addr *net.UDPAddr) bool {
key := addr.IP.String()
lock.Lock()
defer lock.Unlock()
bkt, ok := limiter.Get(key)
if ok {
bkt := bkt.(*ratelimit.Bucket)
if bkt.TakeAvailable(1) != 1 {
// Rate limit exceeded; ignore packet
if debug {
log.Printf("Rate limit exceeded for", key)
}
limited++
return true
} else if debug {
log.Printf("Rate limit OK for", key)
}
} else {
if debug {
log.Printf("New limiter for", key)
}
// One packet per ten seconds average rate, burst ten packets
limiter.Add(key, ratelimit.NewBucket(10*time.Second, 10))
}
return false
}
func handleAnnounceV1(addr *net.UDPAddr, buf []byte) {
var pkt discover.AnnounceV1
err := pkt.UnmarshalXDR(buf)
if err != nil {
log.Println("AnnounceV1 Unmarshal:", err)
log.Println(hex.Dump(buf))
return
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
ip := addr.IP.To4()
if ip == nil {
ip = addr.IP.To16()
}
node := Node{
Addresses: []Address{{
IP: ip,
Port: pkt.Port,
}},
Updated: time.Now(),
}
lock.Lock()
nodes[pkt.NodeID] = node
lock.Unlock()
}
func handleQueryV1(conn *net.UDPConn, addr *net.UDPAddr, buf []byte) {
var pkt discover.QueryV1
err := pkt.UnmarshalXDR(buf)
if err != nil {
log.Println("QueryV1 Unmarshal:", err)
log.Println(hex.Dump(buf))
return
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
lock.Lock()
node, ok := nodes[pkt.NodeID]
queries++
lock.Unlock()
if ok && len(node.Addresses) > 0 {
pkt := discover.AnnounceV1{
Magic: discover.AnnouncementMagicV1,
NodeID: pkt.NodeID,
Port: node.Addresses[0].Port,
IP: node.Addresses[0].IP,
}
if debug {
log.Printf("-> %v %#v", addr, pkt)
}
tb := pkt.MarshalXDR()
_, _, err = conn.WriteMsgUDP(tb, nil, addr)
if err != nil {
log.Println("QueryV1 response write:", err)
}
lock.Lock()
answered++
lock.Unlock()
}
}
func handleAnnounceV2(addr *net.UDPAddr, buf []byte) {
var pkt discover.AnnounceV2
err := pkt.UnmarshalXDR(buf)
if err != nil {
log.Println("AnnounceV2 Unmarshal:", err)
log.Println(hex.Dump(buf))
return
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
ip := addr.IP.To4()
if ip == nil {
ip = addr.IP.To16()
}
var addrs []Address
for _, addr := range pkt.Addresses {
tip := addr.IP
if len(tip) == 0 {
tip = ip
}
addrs = append(addrs, Address{
IP: tip,
Port: addr.Port,
})
}
node := Node{
Addresses: addrs,
Updated: time.Now(),
}
lock.Lock()
nodes[pkt.NodeID] = node
lock.Unlock()
}
func handleQueryV2(conn *net.UDPConn, addr *net.UDPAddr, buf []byte) {
var pkt discover.QueryV2
err := pkt.UnmarshalXDR(buf)
if err != nil {
log.Println("QueryV2 Unmarshal:", err)
log.Println(hex.Dump(buf))
return
}
if debug {
log.Printf("<- %v %#v", addr, pkt)
}
lock.Lock()
node, ok := nodes[pkt.NodeID]
queries++
lock.Unlock()
if ok && len(node.Addresses) > 0 {
pkt := discover.AnnounceV2{
Magic: discover.AnnouncementMagicV2,
NodeID: pkt.NodeID,
}
for _, addr := range node.Addresses {
pkt.Addresses = append(pkt.Addresses, discover.Address{IP: addr.IP, Port: addr.Port})
}
if debug {
log.Printf("-> %v %#v", addr, pkt)
}
tb := pkt.MarshalXDR()
_, _, err = conn.WriteMsgUDP(tb, nil, addr)
if err != nil {
log.Println("QueryV2 response write:", err)
}
lock.Lock()
answered++
lock.Unlock()
}
}
func logStats() {
for {
time.Sleep(600 * time.Second)
lock.Lock()
var deleted = 0
for id, node := range nodes {
if time.Since(node.Updated) > 60*time.Minute {
delete(nodes, id)
deleted++
}
}
log.Printf("Expired %d nodes; %d nodes in registry; %d queries (%d answered); %d entries in limiter cache", deleted, len(nodes), queries, answered, limiter.Len())
log.Printf("Limited %d queries; %d entries in limiter cache", limited, limiter.Len())
queries = 0
answered = 0
limited = 0
lock.Unlock()
}
}