Added ratelimiting of handshake messages

src/device.go

@@ -31,9 +31,10 @@ type Device struct {
 	signal struct {
 		stop chan struct{}
 	}
-	underLoad int32 // used as an atomic bool
-	peers     map[NoisePublicKey]*Peer
-	mac       MACStateDevice
+	underLoad   int32 // used as an atomic bool
+	ratelimiter Ratelimiter
+	peers       map[NoisePublicKey]*Peer
+	mac         MACStateDevice
 }
 
 func (device *Device) SetPrivateKey(sk NoisePrivateKey) {
@@ -66,6 +67,7 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 	device.mtu = tun.MTU()
 	device.peers = make(map[NoisePublicKey]*Peer)
 	device.indices.Init()
+	device.ratelimiter.Init()
 	device.routingTable.Reset()
 
 	// listen
@@ -99,6 +101,7 @@ func NewDevice(tun TUNDevice, logLevel int) *Device {
 	go device.RoutineReadFromTUN(tun)
 	go device.RoutineReceiveIncomming()
 	go device.RoutineWriteToTUN(tun)
+	go device.ratelimiter.RoutineGarbageCollector(device.signal.stop)
 
 	return device
 }

src/ratelimiter.go

@@ -0,0 +1,140 @@
+package main
+
+/* Implementation of the ratelimited form the linux kernel version
+ *
+ *
+ *
+ */
+
+import (
+	"net"
+	"sync"
+	"time"
+)
+
+const (
+	RatelimiterPacketsPerSecond   = 20
+	RatelimiterPacketsBurstable   = 5
+	RatelimiterGarbageCollectTime = time.Second
+	RatelimiterPacketCost         = 1000000000 / RatelimiterPacketsPerSecond
+	RatelimiterMaxTokens          = RatelimiterPacketCost * RatelimiterPacketsBurstable
+)
+
+type RatelimiterEntry struct {
+	mutex    sync.Mutex
+	lastTime time.Time
+	tokens   int64
+}
+
+type Ratelimiter struct {
+	mutex              sync.RWMutex
+	lastGarbageCollect time.Time
+	tableIPv4          map[[net.IPv4len]byte]*RatelimiterEntry
+	tableIPv6          map[[net.IPv6len]byte]*RatelimiterEntry
+}
+
+func (rate *Ratelimiter) Init() {
+	rate.mutex.Lock()
+	defer rate.mutex.Unlock()
+	rate.tableIPv4 = make(map[[net.IPv4len]byte]*RatelimiterEntry)
+	rate.tableIPv6 = make(map[[net.IPv6len]byte]*RatelimiterEntry)
+	rate.lastGarbageCollect = time.Now()
+}
+
+func (rate *Ratelimiter) GarbageCollectEntries() {
+	rate.mutex.Lock()
+
+	// remove unused IPv4 entries
+
+	for key, entry := range rate.tableIPv4 {
+		entry.mutex.Lock()
+		if time.Now().Sub(entry.lastTime) > RatelimiterGarbageCollectTime {
+			delete(rate.tableIPv4, key)
+		}
+		entry.mutex.Unlock()
+	}
+
+	// remove unused IPv6 entries
+
+	for key, entry := range rate.tableIPv6 {
+		entry.mutex.Lock()
+		if time.Now().Sub(entry.lastTime) > RatelimiterGarbageCollectTime {
+			delete(rate.tableIPv6, key)
+		}
+		entry.mutex.Unlock()
+	}
+
+	rate.mutex.Unlock()
+}
+
+func (rate *Ratelimiter) RoutineGarbageCollector(stop chan struct{}) {
+	timer := time.NewTimer(time.Second)
+	for {
+		select {
+		case <-stop:
+			return
+		case <-timer.C:
+			rate.GarbageCollectEntries()
+			timer.Reset(time.Second)
+		}
+	}
+}
+
+func (rate *Ratelimiter) Allow(ip net.IP) bool {
+	var entry *RatelimiterEntry
+	var KeyIPv4 [net.IPv4len]byte
+	var KeyIPv6 [net.IPv6len]byte
+
+	// lookup entry
+
+	IPv4 := ip.To4()
+	IPv6 := ip.To16()
+
+	rate.mutex.RLock()
+
+	if IPv4 != nil {
+		copy(KeyIPv4[:], IPv4)
+		entry = rate.tableIPv4[KeyIPv4]
+	} else {
+		copy(KeyIPv6[:], IPv6)
+		entry = rate.tableIPv6[KeyIPv6]
+	}
+
+	rate.mutex.RUnlock()
+
+	// make new entry if not found
+
+	if entry == nil {
+		rate.mutex.Lock()
+		entry = new(RatelimiterEntry)
+		entry.tokens = RatelimiterMaxTokens - RatelimiterPacketCost
+		entry.lastTime = time.Now()
+		if IPv4 != nil {
+			rate.tableIPv4[KeyIPv4] = entry
+		} else {
+			rate.tableIPv6[KeyIPv6] = entry
+		}
+		rate.mutex.Unlock()
+		return true
+	}
+
+	// add tokens to entry
+
+	entry.mutex.Lock()
+	now := time.Now()
+	entry.tokens += now.Sub(entry.lastTime).Nanoseconds()
+	entry.lastTime = now
+	if entry.tokens > RatelimiterMaxTokens {
+		entry.tokens = RatelimiterMaxTokens
+	}
+
+	// subtract cost of packet
+
+	if entry.tokens > RatelimiterPacketCost {
+		entry.tokens -= RatelimiterPacketCost
+		entry.mutex.Unlock()
+		return true
+	}
+	entry.mutex.Unlock()
+	return false
+}

src/ratelimiter_test.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"net"
+	"testing"
+	"time"
+)
+
+type RatelimiterResult struct {
+	allowed bool
+	text    string
+	wait    time.Duration
+}
+
+func TestRatelimiter(t *testing.T) {
+
+	var ratelimiter Ratelimiter
+	var expectedResults []RatelimiterResult
+
+	Nano := func(nano int64) time.Duration {
+		return time.Nanosecond * time.Duration(nano)
+	}
+
+	Add := func(res RatelimiterResult) {
+		expectedResults = append(
+			expectedResults,
+			res,
+		)
+	}
+
+	for i := 0; i < RatelimiterPacketsBurstable; i++ {
+		Add(RatelimiterResult{
+			allowed: true,
+			text:    "inital burst",
+		})
+	}
+
+	Add(RatelimiterResult{
+		allowed: false,
+		text:    "after burst",
+	})
+
+	Add(RatelimiterResult{
+		allowed: true,
+		wait:    Nano(time.Second.Nanoseconds() / RatelimiterPacketsPerSecond),
+		text:    "filling tokens for single packet",
+	})
+
+	Add(RatelimiterResult{
+		allowed: false,
+		text:    "not having refilled enough",
+	})
+
+	Add(RatelimiterResult{
+		allowed: true,
+		wait:    2 * Nano(time.Second.Nanoseconds()/RatelimiterPacketsPerSecond),
+		text:    "filling tokens for two packet burst",
+	})
+
+	Add(RatelimiterResult{
+		allowed: true,
+		text:    "second packet in 2 packet burst",
+	})
+
+	Add(RatelimiterResult{
+		allowed: false,
+		text:    "packet following 2 packet burst",
+	})
+
+	ips := []net.IP{
+		net.ParseIP("127.0.0.1"),
+		net.ParseIP("192.168.1.1"),
+		net.ParseIP("172.167.2.3"),
+		net.ParseIP("97.231.252.215"),
+		net.ParseIP("248.97.91.167"),
+		net.ParseIP("188.208.233.47"),
+		net.ParseIP("104.2.183.179"),
+		net.ParseIP("72.129.46.120"),
+		net.ParseIP("2001:0db8:0a0b:12f0:0000:0000:0000:0001"),
+		net.ParseIP("f5c2:818f:c052:655a:9860:b136:6894:25f0"),
+		net.ParseIP("b2d7:15ab:48a7:b07c:a541:f144:a9fe:54fc"),
+		net.ParseIP("a47b:786e:1671:a22b:d6f9:4ab0:abc7:c918"),
+		net.ParseIP("ea1e:d155:7f7a:98fb:2bf5:9483:80f6:5445"),
+		net.ParseIP("3f0e:54a2:f5b4:cd19:a21d:58e1:3746:84c4"),
+	}
+
+	ratelimiter.Init()
+
+	for i, res := range expectedResults {
+		time.Sleep(res.wait)
+		for _, ip := range ips {
+			allowed := ratelimiter.Allow(ip)
+			if allowed != res.allowed {
+				t.Fatal("Test failed for", ip.String(), ", on:", i, "(", res.text, ")", "expected:", res.allowed, "got:", allowed)
+			}
+		}
+	}
+}

src/receive.go

@@ -319,6 +319,10 @@ func (device *Device) RoutineHandshake() {
 
 			// ratelimit
 
+			if !device.ratelimiter.Allow(elem.source.IP) {
+				return
+			}
+
 			// handle messages
 
 			switch elem.msgType {

src/replay_test.go

@@ -9,8 +9,6 @@ import (
  *
  */
 
-/* Copyright (C) 2015-2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
-
 func TestReplay(t *testing.T) {
 	var filter ReplayFilter