forked from syncthing/syncthing
/
main.go
256 lines (216 loc) · 4.58 KB
/
main.go
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package main
import (
"encoding/binary"
"encoding/hex"
"flag"
"fmt"
"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
announces = 0
answered = 0
limited = 0
unknowns = 0
debug = false
limiter = lru.New(1024)
)
func main() {
var listen string
var timestamp bool
var statsIntv int
var statsFile string
flag.StringVar(&listen, "listen", ":22025", "Listen address")
flag.BoolVar(&debug, "debug", false, "Enable debug output")
flag.BoolVar(×tamp, "timestamp", true, "Timestamp the log output")
flag.IntVar(&statsIntv, "stats-intv", 0, "Statistics output interval (s)")
flag.StringVar(&statsFile, "stats-file", "/var/log/discosrv.stats", "Statistics file name")
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)
}
if statsIntv > 0 {
go logStats(statsFile, statsIntv)
}
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.AnnouncementMagicV2:
handleAnnounceV2(addr, buf)
case discover.QueryMagicV2:
handleQueryV2(conn, addr, buf)
default:
lock.Lock()
unknowns++
lock.Unlock()
}
}
}
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.Println("Rate limit exceeded for", key)
}
limited++
return true
}
} else {
if debug {
log.Println("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 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)
}
lock.Lock()
announces++
lock.Unlock()
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 next(intv int) time.Time {
d := time.Duration(intv) * time.Second
t0 := time.Now()
t1 := t0.Add(d).Truncate(d)
time.Sleep(t1.Sub(t0))
return t1
}
func logStats(file string, intv int) {
f, err := os.OpenFile(file, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
log.Fatal(err)
}
for {
t := next(intv)
lock.Lock()
var deleted = 0
for id, node := range nodes {
if time.Since(node.Updated) > 60*time.Minute {
delete(nodes, id)
deleted++
}
}
fmt.Fprintf(f, "%d Nr:%d Ne:%d Qt:%d Qa:%d A:%d U:%d Lq:%d Lc:%d\n",
t.Unix(), len(nodes), deleted, queries, answered, announces, unknowns, limited, limiter.Len())
f.Sync()
queries = 0
announces = 0
answered = 0
limited = 0
unknowns = 0
lock.Unlock()
}
}