From 7c1587e3401a010d1865df61dbaf117c77dd062e Mon Sep 17 00:00:00 2001 From: Ian Gudger Date: Mon, 7 Oct 2019 19:28:26 -0700 Subject: Implement IP_TTL. Also change the default TTL to 64 to match Linux. PiperOrigin-RevId: 273430341 --- pkg/tcpip/transport/tcp/accept.go | 2 +- pkg/tcpip/transport/tcp/connect.go | 20 ++++++++++++-------- pkg/tcpip/transport/tcp/endpoint.go | 13 +++++++++++++ pkg/tcpip/transport/tcp/tcp_test.go | 28 ++++++++++++++++++++++++++++ 4 files changed, 54 insertions(+), 9 deletions(-) (limited to 'pkg/tcpip/transport/tcp') diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go index 3ae4a5426..b8b4bcee8 100644 --- a/pkg/tcpip/transport/tcp/accept.go +++ b/pkg/tcpip/transport/tcp/accept.go @@ -439,7 +439,7 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) { TSEcr: opts.TSVal, MSS: uint16(mss), } - sendSynTCP(&s.route, s.id, header.TCPFlagSyn|header.TCPFlagAck, cookie, s.sequenceNumber+1, ctx.rcvWnd, synOpts) + sendSynTCP(&s.route, s.id, e.ttl, header.TCPFlagSyn|header.TCPFlagAck, cookie, s.sequenceNumber+1, ctx.rcvWnd, synOpts) e.stack.Stats().TCP.ListenOverflowSynCookieSent.Increment() } diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 21038a65a..1d6e7f5f3 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -238,6 +238,7 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error { h.state = handshakeSynRcvd h.ep.mu.Lock() h.ep.state = StateSynRecv + ttl := h.ep.ttl h.ep.mu.Unlock() synOpts := header.TCPSynOptions{ WS: int(h.effectiveRcvWndScale()), @@ -251,7 +252,10 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error { SACKPermitted: rcvSynOpts.SACKPermitted, MSS: h.ep.amss, } - sendSynTCP(&s.route, h.ep.id, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) + if ttl == 0 { + ttl = s.route.DefaultTTL() + } + sendSynTCP(&s.route, h.ep.id, ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) return nil } @@ -296,7 +300,7 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error { SACKPermitted: h.ep.sackPermitted, MSS: h.ep.amss, } - sendSynTCP(&s.route, h.ep.id, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) + sendSynTCP(&s.route, h.ep.id, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) return nil } @@ -460,7 +464,7 @@ func (h *handshake) execute() *tcpip.Error { synOpts.WS = -1 } } - sendSynTCP(&h.ep.route, h.ep.id, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) + sendSynTCP(&h.ep.route, h.ep.id, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) for h.state != handshakeCompleted { switch index, _ := s.Fetch(true); index { case wakerForResend: @@ -469,7 +473,7 @@ func (h *handshake) execute() *tcpip.Error { return tcpip.ErrTimeout } rt.Reset(timeOut) - sendSynTCP(&h.ep.route, h.ep.id, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) + sendSynTCP(&h.ep.route, h.ep.id, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts) case wakerForNotification: n := h.ep.fetchNotifications() @@ -579,9 +583,9 @@ func makeSynOptions(opts header.TCPSynOptions) []byte { return options[:offset] } -func sendSynTCP(r *stack.Route, id stack.TransportEndpointID, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts header.TCPSynOptions) *tcpip.Error { +func sendSynTCP(r *stack.Route, id stack.TransportEndpointID, ttl uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts header.TCPSynOptions) *tcpip.Error { options := makeSynOptions(opts) - err := sendTCP(r, id, buffer.VectorisedView{}, r.DefaultTTL(), flags, seq, ack, rcvWnd, options, nil) + err := sendTCP(r, id, buffer.VectorisedView{}, ttl, flags, seq, ack, rcvWnd, options, nil) putOptions(options) return err } @@ -629,7 +633,7 @@ func sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.Vectorise r.Stats().TCP.ResetsSent.Increment() } - return r.WritePacket(gso, hdr, data, ProtocolNumber, ttl) + return r.WritePacket(gso, hdr, data, ProtocolNumber, ttl, ttl == 0 /* useDefaultTTL */) } // makeOptions makes an options slice. @@ -678,7 +682,7 @@ func (e *endpoint) sendRaw(data buffer.VectorisedView, flags byte, seq, ack seqn sackBlocks = e.sack.Blocks[:e.sack.NumBlocks] } options := e.makeOptions(sackBlocks) - err := sendTCP(&e.route, e.id, data, e.route.DefaultTTL(), flags, seq, ack, rcvWnd, options, e.gso) + err := sendTCP(&e.route, e.id, data, e.ttl, flags, seq, ack, rcvWnd, options, e.gso) putOptions(options) return err } diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index f9d5e0085..83d92b3e1 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -228,6 +228,7 @@ type endpoint struct { isRegistered bool boundNICID tcpip.NICID `state:"manual"` route stack.Route `state:"manual"` + ttl uint8 v6only bool isConnectNotified bool // TCP should never broadcast but Linux nevertheless supports enabling/ @@ -1116,6 +1117,12 @@ func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error { e.v6only = v != 0 return nil + case tcpip.TTLOption: + e.mu.Lock() + e.ttl = uint8(v) + e.mu.Unlock() + return nil + case tcpip.KeepaliveEnabledOption: e.keepalive.Lock() e.keepalive.enabled = v != 0 @@ -1313,6 +1320,12 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error { } return nil + case *tcpip.TTLOption: + e.mu.Lock() + *o = tcpip.TTLOption(e.ttl) + e.mu.Unlock() + return nil + case *tcpip.TCPInfoOption: *o = tcpip.TCPInfoOption{} e.mu.RLock() diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go index 089826a88..a86123829 100644 --- a/pkg/tcpip/transport/tcp/tcp_test.go +++ b/pkg/tcpip/transport/tcp/tcp_test.go @@ -1752,6 +1752,34 @@ func TestSendGreaterThanMTU(t *testing.T) { testBrokenUpWrite(t, c, maxPayload) } +func TestSetTTL(t *testing.T) { + for _, wantTTL := range []uint8{1, 2, 50, 64, 128, 254, 255} { + t.Run(fmt.Sprintf("TTL:%d", wantTTL), func(t *testing.T) { + c := context.New(t, 65535) + defer c.Cleanup() + + var err *tcpip.Error + c.EP, err = c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &waiter.Queue{}) + if err != nil { + t.Fatalf("NewEndpoint failed: %v", err) + } + + if err := c.EP.SetSockOpt(tcpip.TTLOption(wantTTL)); err != nil { + t.Fatalf("SetSockOpt failed: %v", err) + } + + if err := c.EP.Connect(tcpip.FullAddress{Addr: context.TestAddr, Port: context.TestPort}); err != tcpip.ErrConnectStarted { + t.Fatalf("Unexpected return value from Connect: %v", err) + } + + // Receive SYN packet. + b := c.GetPacket() + + checker.IPv4(t, b, checker.TTL(wantTTL)) + }) + } +} + func TestActiveSendMSSLessThanMTU(t *testing.T) { const maxPayload = 100 c := context.New(t, 65535) -- cgit v1.2.3