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-rw-r--r--pkg/tcpip/tcpip.go19
-rw-r--r--pkg/tcpip/transport/tcp/accept.go161
-rw-r--r--pkg/tcpip/transport/tcp/connect.go27
-rw-r--r--pkg/tcpip/transport/tcp/endpoint.go6
-rw-r--r--pkg/tcpip/transport/tcp/forwarder.go2
-rw-r--r--pkg/tcpip/transport/tcp/tcp_test.go499
-rw-r--r--pkg/tcpip/transport/tcp/testing/context/context.go6
7 files changed, 624 insertions, 96 deletions
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index c8164c0f0..f9886c6e4 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -760,6 +760,25 @@ type TCPStats struct {
// successfully via Listen.
PassiveConnectionOpenings *StatCounter
+ // ListenOverflowSynDrop is the number of times the listen queue overflowed
+ // and a SYN was dropped.
+ ListenOverflowSynDrop *StatCounter
+
+ // ListenOverflowAckDrop is the number of times the final ACK
+ // in the handshake was dropped due to overflow.
+ ListenOverflowAckDrop *StatCounter
+
+ // ListenOverflowCookieSent is the number of times a SYN cookie was sent.
+ ListenOverflowSynCookieSent *StatCounter
+
+ // ListenOverflowSynCookieRcvd is the number of times a valid SYN
+ // cookie was received.
+ ListenOverflowSynCookieRcvd *StatCounter
+
+ // ListenOverflowInvalidSynCookieRcvd is the number of times an invalid SYN cookie
+ // was received.
+ ListenOverflowInvalidSynCookieRcvd *StatCounter
+
// FailedConnectionAttempts is the number of calls to Connect or Listen
// (active and passive openings, respectively) that end in an error.
FailedConnectionAttempts *StatCounter
diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go
index e506d7133..d4b860975 100644
--- a/pkg/tcpip/transport/tcp/accept.go
+++ b/pkg/tcpip/transport/tcp/accept.go
@@ -19,6 +19,7 @@ import (
"encoding/binary"
"hash"
"io"
+ "log"
"sync"
"time"
@@ -87,9 +88,10 @@ var synRcvdCount struct {
// and must not be accessed or have its methods called concurrently as they
// may mutate the stored objects.
type listenContext struct {
- stack *stack.Stack
- rcvWnd seqnum.Size
- nonce [2][sha1.BlockSize]byte
+ stack *stack.Stack
+ rcvWnd seqnum.Size
+ nonce [2][sha1.BlockSize]byte
+ listenEP *endpoint
hasherMu sync.Mutex
hasher hash.Hash
@@ -107,15 +109,16 @@ func timeStamp() uint32 {
// threshold, and fails otherwise.
func incSynRcvdCount() bool {
synRcvdCount.Lock()
- defer synRcvdCount.Unlock()
if synRcvdCount.value >= SynRcvdCountThreshold {
+ synRcvdCount.Unlock()
return false
}
synRcvdCount.pending.Add(1)
synRcvdCount.value++
+ synRcvdCount.Unlock()
return true
}
@@ -124,20 +127,21 @@ func incSynRcvdCount() bool {
// succeeded.
func decSynRcvdCount() {
synRcvdCount.Lock()
- defer synRcvdCount.Unlock()
synRcvdCount.value--
synRcvdCount.pending.Done()
+ synRcvdCount.Unlock()
}
// newListenContext creates a new listen context.
-func newListenContext(stack *stack.Stack, rcvWnd seqnum.Size, v6only bool, netProto tcpip.NetworkProtocolNumber) *listenContext {
+func newListenContext(stack *stack.Stack, listenEP *endpoint, rcvWnd seqnum.Size, v6only bool, netProto tcpip.NetworkProtocolNumber) *listenContext {
l := &listenContext{
stack: stack,
rcvWnd: rcvWnd,
hasher: sha1.New(),
v6only: v6only,
netProto: netProto,
+ listenEP: listenEP,
}
rand.Read(l.nonce[0][:])
@@ -195,9 +199,9 @@ func (l *listenContext) isCookieValid(id stack.TransportEndpointID, cookie seqnu
return (v - l.cookieHash(id, cookieTS, 1)) & hashMask, true
}
-// createConnectedEndpoint creates a new connected endpoint, with the connection
-// parameters given by the arguments.
-func (l *listenContext) createConnectedEndpoint(s *segment, iss seqnum.Value, irs seqnum.Value, rcvdSynOpts *header.TCPSynOptions) (*endpoint, *tcpip.Error) {
+// createConnectingEndpoint creates a new endpoint in a connecting state, with
+// the connection parameters given by the arguments.
+func (l *listenContext) createConnectingEndpoint(s *segment, iss seqnum.Value, irs seqnum.Value, rcvdSynOpts *header.TCPSynOptions) (*endpoint, *tcpip.Error) {
// Create a new endpoint.
netProto := l.netProto
if netProto == 0 {
@@ -223,7 +227,7 @@ func (l *listenContext) createConnectedEndpoint(s *segment, iss seqnum.Value, ir
}
n.isRegistered = true
- n.state = stateConnected
+ n.state = stateConnecting
// Create sender and receiver.
//
@@ -241,7 +245,7 @@ func (l *listenContext) createEndpointAndPerformHandshake(s *segment, opts *head
// Create new endpoint.
irs := s.sequenceNumber
cookie := l.createCookie(s.id, irs, encodeMSS(opts.MSS))
- ep, err := l.createConnectedEndpoint(s, cookie, irs, opts)
+ ep, err := l.createConnectingEndpoint(s, cookie, irs, opts)
if err != nil {
return nil, err
}
@@ -249,12 +253,15 @@ func (l *listenContext) createEndpointAndPerformHandshake(s *segment, opts *head
// Perform the 3-way handshake.
h := newHandshake(ep, l.rcvWnd)
- h.resetToSynRcvd(cookie, irs, opts)
+ h.resetToSynRcvd(cookie, irs, opts, l.listenEP)
if err := h.execute(); err != nil {
+ ep.stack.Stats().TCP.FailedConnectionAttempts.Increment()
ep.Close()
return nil, err
}
+ ep.state = stateConnected
+
// Update the receive window scaling. We can't do it before the
// handshake because it's possible that the peer doesn't support window
// scaling.
@@ -268,13 +275,14 @@ func (l *listenContext) createEndpointAndPerformHandshake(s *segment, opts *head
// instead.
func (e *endpoint) deliverAccepted(n *endpoint) {
e.mu.RLock()
- if e.state == stateListen {
+ state := e.state
+ e.mu.RUnlock()
+ if state == stateListen {
e.acceptedChan <- n
e.waiterQueue.Notify(waiter.EventIn)
} else {
n.Close()
}
- e.mu.RUnlock()
}
// handleSynSegment is called in its own goroutine once the listening endpoint
@@ -285,16 +293,36 @@ func (e *endpoint) deliverAccepted(n *endpoint) {
// cookies to accept connections.
func (e *endpoint) handleSynSegment(ctx *listenContext, s *segment, opts *header.TCPSynOptions) {
defer decSynRcvdCount()
+ defer e.decSynRcvdCount()
defer s.decRef()
n, err := ctx.createEndpointAndPerformHandshake(s, opts)
if err != nil {
+ e.stack.Stats().TCP.FailedConnectionAttempts.Increment()
return
}
e.deliverAccepted(n)
}
+func (e *endpoint) incSynRcvdCount() bool {
+ e.mu.Lock()
+ log.Printf("l: %d, c: %d, e.synRcvdCount: %d", len(e.acceptedChan), cap(e.acceptedChan), e.synRcvdCount)
+ if l, c := len(e.acceptedChan), cap(e.acceptedChan); l == c && e.synRcvdCount >= c {
+ e.mu.Unlock()
+ return false
+ }
+ e.synRcvdCount++
+ e.mu.Unlock()
+ return true
+}
+
+func (e *endpoint) decSynRcvdCount() {
+ e.mu.Lock()
+ e.synRcvdCount--
+ e.mu.Unlock()
+}
+
// handleListenSegment is called when a listening endpoint receives a segment
// and needs to handle it.
func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) {
@@ -302,9 +330,20 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) {
case header.TCPFlagSyn:
opts := parseSynSegmentOptions(s)
if incSynRcvdCount() {
- s.incRef()
- go e.handleSynSegment(ctx, s, &opts) // S/R-SAFE: synRcvdCount is the barrier.
+ // Drop the SYN if the listen endpoint's accept queue is
+ // overflowing.
+ if e.incSynRcvdCount() {
+ log.Printf("processing syn packet")
+ s.incRef()
+ go e.handleSynSegment(ctx, s, &opts) // S/R-SAFE: synRcvdCount is the barrier.
+ return
+ }
+ log.Printf("dropping syn packet")
+ e.stack.Stats().TCP.ListenOverflowSynDrop.Increment()
+ e.stack.Stats().DroppedPackets.Increment()
+ return
} else {
+ // TODO(bhaskerh): Increment syncookie sent stat.
cookie := ctx.createCookie(s.id, s.sequenceNumber, encodeMSS(opts.MSS))
// Send SYN with window scaling because we currently
// dont't encode this information in the cookie.
@@ -318,36 +357,72 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) {
TSEcr: opts.TSVal,
}
sendSynTCP(&s.route, s.id, header.TCPFlagSyn|header.TCPFlagAck, cookie, s.sequenceNumber+1, ctx.rcvWnd, synOpts)
+ e.stack.Stats().TCP.ListenOverflowSynCookieSent.Increment()
}
case header.TCPFlagAck:
- if data, ok := ctx.isCookieValid(s.id, s.ackNumber-1, s.sequenceNumber-1); ok && int(data) < len(mssTable) {
- // Create newly accepted endpoint and deliver it.
- rcvdSynOptions := &header.TCPSynOptions{
- MSS: mssTable[data],
- // Disable Window scaling as original SYN is
- // lost.
- WS: -1,
- }
- // When syn cookies are in use we enable timestamp only
- // if the ack specifies the timestamp option assuming
- // that the other end did in fact negotiate the
- // timestamp option in the original SYN.
- if s.parsedOptions.TS {
- rcvdSynOptions.TS = true
- rcvdSynOptions.TSVal = s.parsedOptions.TSVal
- rcvdSynOptions.TSEcr = s.parsedOptions.TSEcr
- }
- n, err := ctx.createConnectedEndpoint(s, s.ackNumber-1, s.sequenceNumber-1, rcvdSynOptions)
- if err == nil {
- // clear the tsOffset for the newly created
- // endpoint as the Timestamp was already
- // randomly offset when the original SYN-ACK was
- // sent above.
- n.tsOffset = 0
- e.deliverAccepted(n)
- }
+ if len(e.acceptedChan) == cap(e.acceptedChan) {
+ // Silently drop the ack as the application can't accept
+ // the connection at this point. The ack will be
+ // retransmitted by the sender anyway and we can
+ // complete the connection at the time of retransmit if
+ // the backlog has space.
+ e.stack.Stats().TCP.ListenOverflowAckDrop.Increment()
+ e.stack.Stats().DroppedPackets.Increment()
+ return
+ }
+
+ // Validate the cookie.
+ data, ok := ctx.isCookieValid(s.id, s.ackNumber-1, s.sequenceNumber-1)
+ if !ok || int(data) >= len(mssTable) {
+ e.stack.Stats().TCP.ListenOverflowInvalidSynCookieRcvd.Increment()
+ e.stack.Stats().DroppedPackets.Increment()
+ return
}
+ e.stack.Stats().TCP.ListenOverflowSynCookieRcvd.Increment()
+ // Create newly accepted endpoint and deliver it.
+ rcvdSynOptions := &header.TCPSynOptions{
+ MSS: mssTable[data],
+ // Disable Window scaling as original SYN is
+ // lost.
+ WS: -1,
+ }
+
+ // When syn cookies are in use we enable timestamp only
+ // if the ack specifies the timestamp option assuming
+ // that the other end did in fact negotiate the
+ // timestamp option in the original SYN.
+ if s.parsedOptions.TS {
+ rcvdSynOptions.TS = true
+ rcvdSynOptions.TSVal = s.parsedOptions.TSVal
+ rcvdSynOptions.TSEcr = s.parsedOptions.TSEcr
+ }
+
+ n, err := ctx.createConnectingEndpoint(s, s.ackNumber-1, s.sequenceNumber-1, rcvdSynOptions)
+ if err != nil {
+ e.stack.Stats().TCP.FailedConnectionAttempts.Increment()
+ return
+ }
+
+ // clear the tsOffset for the newly created
+ // endpoint as the Timestamp was already
+ // randomly offset when the original SYN-ACK was
+ // sent above.
+ n.tsOffset = 0
+
+ // Switch state to connected.
+ n.state = stateConnected
+
+ // Do the delivery in a separate goroutine so
+ // that we don't block the listen loop in case
+ // the application is slow to accept or stops
+ // accepting.
+ //
+ // NOTE: This won't result in an unbounded
+ // number of goroutines as we do check before
+ // entering here that there was at least some
+ // space available in the backlog.
+ go e.deliverAccepted(n)
}
}
@@ -377,7 +452,7 @@ func (e *endpoint) protocolListenLoop(rcvWnd seqnum.Size) *tcpip.Error {
v6only := e.v6only
e.mu.Unlock()
- ctx := newListenContext(e.stack, rcvWnd, v6only, e.netProto)
+ ctx := newListenContext(e.stack, e, rcvWnd, v6only, e.netProto)
s := sleep.Sleeper{}
s.AddWaker(&e.notificationWaker, wakerForNotification)
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 3b927d82e..2aed6f286 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -60,11 +60,12 @@ const (
// handshake holds the state used during a TCP 3-way handshake.
type handshake struct {
- ep *endpoint
- state handshakeState
- active bool
- flags uint8
- ackNum seqnum.Value
+ ep *endpoint
+ listenEP *endpoint // only non nil when doing passive connects.
+ state handshakeState
+ active bool
+ flags uint8
+ ackNum seqnum.Value
// iss is the initial send sequence number, as defined in RFC 793.
iss seqnum.Value
@@ -141,7 +142,7 @@ func (h *handshake) effectiveRcvWndScale() uint8 {
// resetToSynRcvd resets the state of the handshake object to the SYN-RCVD
// state.
-func (h *handshake) resetToSynRcvd(iss seqnum.Value, irs seqnum.Value, opts *header.TCPSynOptions) {
+func (h *handshake) resetToSynRcvd(iss seqnum.Value, irs seqnum.Value, opts *header.TCPSynOptions, listenEP *endpoint) {
h.active = false
h.state = handshakeSynRcvd
h.flags = header.TCPFlagSyn | header.TCPFlagAck
@@ -149,6 +150,7 @@ func (h *handshake) resetToSynRcvd(iss seqnum.Value, irs seqnum.Value, opts *hea
h.ackNum = irs + 1
h.mss = opts.MSS
h.sndWndScale = opts.WS
+ h.listenEP = listenEP
}
// checkAck checks if the ACK number, if present, of a segment received during
@@ -279,7 +281,18 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error {
// We have previously received (and acknowledged) the peer's SYN. If the
// peer acknowledges our SYN, the handshake is completed.
if s.flagIsSet(header.TCPFlagAck) {
-
+ // listenContext is also used by a tcp.Forwarder and in that
+ // context we do not have a listening endpoint to check the
+ // backlog. So skip this check if listenEP is nil.
+ if h.listenEP != nil && len(h.listenEP.acceptedChan) == cap(h.listenEP.acceptedChan) {
+ // If there is no space in the accept queue to accept
+ // this endpoint then silently drop this ACK. The peer
+ // will anyway resend the ack and we can complete the
+ // connection the next time it's retransmitted.
+ h.ep.stack.Stats().TCP.ListenOverflowAckDrop.Increment()
+ h.ep.stack.Stats().DroppedPackets.Increment()
+ return nil
+ }
// If the timestamp option is negotiated and the segment does
// not carry a timestamp option then the segment must be dropped
// as per https://tools.ietf.org/html/rfc7323#section-3.2.
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 00962a63e..b66610ee2 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -198,6 +198,10 @@ type endpoint struct {
// and dropped when it is.
segmentQueue segmentQueue `state:"wait"`
+ // synRcvdCount is the number of connections for this endpoint that are
+ // in SYN-RCVD state.
+ synRcvdCount int
+
// The following fields are used to manage the send buffer. When
// segments are ready to be sent, they are added to sndQueue and the
// protocol goroutine is signaled via sndWaker.
@@ -1302,7 +1306,6 @@ func (e *endpoint) Listen(backlog int) (err *tcpip.Error) {
}
e.workerRunning = true
- e.stack.Stats().TCP.PassiveConnectionOpenings.Increment()
go e.protocolListenLoop( // S/R-SAFE: drained on save.
seqnum.Size(e.receiveBufferAvailable()))
@@ -1339,6 +1342,7 @@ func (e *endpoint) Accept() (tcpip.Endpoint, *waiter.Queue, *tcpip.Error) {
// Start the protocol goroutine.
wq := &waiter.Queue{}
n.startAcceptedLoop(wq)
+ e.stack.Stats().TCP.PassiveConnectionOpenings.Increment()
return n, wq, nil
}
diff --git a/pkg/tcpip/transport/tcp/forwarder.go b/pkg/tcpip/transport/tcp/forwarder.go
index e088e24cb..c30b45c2c 100644
--- a/pkg/tcpip/transport/tcp/forwarder.go
+++ b/pkg/tcpip/transport/tcp/forwarder.go
@@ -53,7 +53,7 @@ func NewForwarder(s *stack.Stack, rcvWnd, maxInFlight int, handler func(*Forward
maxInFlight: maxInFlight,
handler: handler,
inFlight: make(map[stack.TransportEndpointID]struct{}),
- listen: newListenContext(s, seqnum.Size(rcvWnd), true, 0),
+ listen: newListenContext(s, nil /* listenEP */, seqnum.Size(rcvWnd), true, 0),
}
}
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index e341bb4aa..fe037602b 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -124,50 +124,6 @@ func TestActiveFailedConnectionAttemptIncrement(t *testing.T) {
}
}
-func TestPassiveConnectionAttemptIncrement(t *testing.T) {
- c := context.New(t, defaultMTU)
- defer c.Cleanup()
-
- stats := c.Stack().Stats()
- want := stats.TCP.PassiveConnectionOpenings.Value() + 1
- ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
- if err != nil {
- t.Fatalf("NewEndpoint failed: %v", err)
- }
-
- if err := ep.Bind(tcpip.FullAddress{Addr: context.StackAddr, Port: context.StackPort}); err != nil {
- t.Fatalf("Bind failed: %v", err)
- }
- if err := ep.Listen(1); err != nil {
- t.Fatalf("Listen failed: %v", err)
- }
-
- if got := stats.TCP.PassiveConnectionOpenings.Value(); got != want {
- t.Errorf("got stats.TCP.PassiveConnectionOpenings.Value() = %v, want = %v", got, want)
- }
-}
-
-func TestPassiveFailedConnectionAttemptIncrement(t *testing.T) {
- c := context.New(t, defaultMTU)
- defer c.Cleanup()
-
- stats := c.Stack().Stats()
- ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
- if err != nil {
- t.Fatalf("NewEndpoint failed: %v", err)
- }
- c.EP = ep
- want := stats.TCP.FailedConnectionAttempts.Value() + 1
-
- if err := ep.Listen(1); err != tcpip.ErrInvalidEndpointState {
- t.Errorf("got ep.Listen(1) = %v, want = %v", err, tcpip.ErrInvalidEndpointState)
- }
-
- if got := stats.TCP.FailedConnectionAttempts.Value(); got != want {
- t.Errorf("got stats.TCP.FailedConnectionAttempts.Value() = %v, want = %v", got, want)
- }
-}
-
func TestTCPSegmentsSentIncrement(t *testing.T) {
c := context.New(t, defaultMTU)
defer c.Cleanup()
@@ -3900,3 +3856,458 @@ func TestKeepalive(t *testing.T) {
t.Fatalf("got c.EP.Read(nil) = %v, want = %v", err, tcpip.ErrConnectionReset)
}
}
+
+func executeHandshake(t *testing.T, c *context.Context, srcPort uint16, synCookieInUse bool) (irs, iss seqnum.Value) {
+ // Send a SYN request.
+ irs = seqnum.Value(789)
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: srcPort,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagSyn,
+ SeqNum: irs,
+ RcvWnd: 30000,
+ })
+
+ // Receive the SYN-ACK reply.
+ b := c.GetPacket()
+ tcp := header.TCP(header.IPv4(b).Payload())
+ iss = seqnum.Value(tcp.SequenceNumber())
+ tcpCheckers := []checker.TransportChecker{
+ checker.SrcPort(context.StackPort),
+ checker.DstPort(srcPort),
+ checker.TCPFlags(header.TCPFlagAck | header.TCPFlagSyn),
+ checker.AckNum(uint32(irs) + 1),
+ }
+
+ if synCookieInUse {
+ // When cookies are in use window scaling is disabled.
+ tcpCheckers = append(tcpCheckers, checker.TCPSynOptions(header.TCPSynOptions{
+ WS: -1,
+ MSS: c.MSSWithoutOptions(),
+ }))
+ }
+
+ checker.IPv4(t, b, checker.TCP(tcpCheckers...))
+
+ // Send ACK.
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: srcPort,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagAck,
+ SeqNum: irs + 1,
+ AckNum: iss + 1,
+ RcvWnd: 30000,
+ })
+ return irs, iss
+}
+
+// TestListenBacklogFull tests that netstack does not complete handshakes if the
+// listen backlog for the endpoint is full.
+func TestListenBacklogFull(t *testing.T) {
+ c := context.New(t, defaultMTU)
+ defer c.Cleanup()
+
+ // Create TCP endpoint.
+ var err *tcpip.Error
+ c.EP, err = c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
+ if err != nil {
+ t.Fatalf("NewEndpoint failed: %v", err)
+ }
+
+ // Bind to wildcard.
+ if err := c.EP.Bind(tcpip.FullAddress{Port: context.StackPort}); err != nil {
+ t.Fatalf("Bind failed: %v", err)
+ }
+
+ // Test acceptance.
+ // Start listening.
+ listenBacklog := 2
+ if err := c.EP.Listen(listenBacklog); err != nil {
+ t.Fatalf("Listen failed: %v", err)
+ }
+
+ for i := 0; i < listenBacklog; i++ {
+ executeHandshake(t, c, context.TestPort+uint16(i), false /*synCookieInUse */)
+ }
+
+ time.Sleep(50 * time.Millisecond)
+
+ // Now execute one more handshake. This should not be completed and
+ // delivered on an Accept() call as the backlog is full at this point.
+ irs, iss := executeHandshake(t, c, context.TestPort+uint16(listenBacklog), false /* synCookieInUse */)
+
+ time.Sleep(50 * time.Millisecond)
+ // Try to accept the connection.
+ we, ch := waiter.NewChannelEntry(nil)
+ c.WQ.EventRegister(&we, waiter.EventIn)
+ defer c.WQ.EventUnregister(&we)
+
+ for i := 0; i < listenBacklog; i++ {
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+ }
+
+ // Now verify that there are no more connections that can be accepted.
+ _, _, err = c.EP.Accept()
+ if err != tcpip.ErrWouldBlock {
+ select {
+ case <-ch:
+ t.Fatalf("unexpected endpoint delivered on Accept: %+v", c.EP)
+ case <-time.After(1 * time.Second):
+ }
+ }
+
+ // Now craft the ACK again and verify that the connection is now ready
+ // to be accepted.
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: context.TestPort + uint16(listenBacklog),
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagAck,
+ SeqNum: irs + 1,
+ AckNum: iss + 1,
+ RcvWnd: 30000,
+ })
+
+ newEP, _, err := c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ newEP, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+ // Now verify that the TCP socket is usable and in a connected state.
+ data := "Don't panic"
+ newEP.Write(tcpip.SlicePayload(buffer.NewViewFromBytes([]byte(data))), tcpip.WriteOptions{})
+ b := c.GetPacket()
+ tcp := header.TCP(header.IPv4(b).Payload())
+ if string(tcp.Payload()) != data {
+ t.Fatalf("Unexpected data: got %v, want %v", string(tcp.Payload()), data)
+ }
+}
+
+func TestListenBacklogFullSynCookieInUse(t *testing.T) {
+ saved := tcp.SynRcvdCountThreshold
+ defer func() {
+ tcp.SynRcvdCountThreshold = saved
+ }()
+ tcp.SynRcvdCountThreshold = 1
+
+ c := context.New(t, defaultMTU)
+ defer c.Cleanup()
+
+ // Create TCP endpoint.
+ var err *tcpip.Error
+ c.EP, err = c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
+ if err != nil {
+ t.Fatalf("NewEndpoint failed: %v", err)
+ }
+
+ // Bind to wildcard.
+ if err := c.EP.Bind(tcpip.FullAddress{Port: context.StackPort}); err != nil {
+ t.Fatalf("Bind failed: %v", err)
+ }
+
+ // Test acceptance.
+ // Start listening.
+ listenBacklog := 1
+ portOffset := uint16(0)
+ if err := c.EP.Listen(listenBacklog); err != nil {
+ t.Fatalf("Listen failed: %v", err)
+ }
+
+ executeHandshake(t, c, context.TestPort+portOffset, false)
+ portOffset++
+ // Wait for this to be delivered to the accept queue.
+ time.Sleep(50 * time.Millisecond)
+
+ nonCookieIRS, nonCookieISS := executeHandshake(t, c, context.TestPort+portOffset, false)
+
+ // Since the backlog is full at this point this connection will not
+ // transition out of handshake and ignore the ACK.
+ //
+ // At this point there should be 1 completed connection in the backlog
+ // and one incomplete one pending for a final ACK and hence not ready to be
+ // delivered to the endpoint.
+ //
+ // Now execute one more handshake. This should not be completed and
+ // delivered on an Accept() call as the backlog is full at this point
+ // and there is already 1 pending endpoint.
+ //
+ // This one should use a SYN cookie as the synRcvdCount is equal to the
+ // SynRcvdCountThreshold.
+ time.Sleep(50 * time.Millisecond)
+ portOffset++
+ irs, iss := executeHandshake(t, c, context.TestPort+portOffset, true)
+
+ time.Sleep(50 * time.Millisecond)
+
+ // Verify that there is only one acceptable connection at this point.
+ we, ch := waiter.NewChannelEntry(nil)
+ c.WQ.EventRegister(&we, waiter.EventIn)
+ defer c.WQ.EventUnregister(&we)
+
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ // Now verify that there are no more connections that can be accepted.
+ _, _, err = c.EP.Accept()
+ if err != tcpip.ErrWouldBlock {
+ select {
+ case <-ch:
+ t.Fatalf("unexpected endpoint delivered on Accept: %+v", c.EP)
+ case <-time.After(1 * time.Second):
+ }
+ }
+
+ // Now send an ACK for the half completed connection
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: context.TestPort + portOffset - 1,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagAck,
+ SeqNum: nonCookieIRS + 1,
+ AckNum: nonCookieISS + 1,
+ RcvWnd: 30000,
+ })
+
+ // Verify that the connection is now delivered to the backlog.
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ // Finally send an ACK for the connection that used a cookie and verify that
+ // it's also completed and delivered.
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: context.TestPort + portOffset,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagAck,
+ SeqNum: irs,
+ AckNum: iss,
+ RcvWnd: 30000,
+ })
+
+ time.Sleep(50 * time.Millisecond)
+ newEP, _, err := c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ newEP, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ // Now verify that the TCP socket is usable and in a connected state.
+ data := "Don't panic"
+ newEP.Write(tcpip.SlicePayload(buffer.NewViewFromBytes([]byte(data))), tcpip.WriteOptions{})
+ b := c.GetPacket()
+ tcp := header.TCP(header.IPv4(b).Payload())
+ if string(tcp.Payload()) != data {
+ t.Fatalf("Unexpected data: got %v, want %v", string(tcp.Payload()), data)
+ }
+}
+
+func TestPassiveConnectionAttemptIncrement(t *testing.T) {
+ c := context.New(t, defaultMTU)
+ defer c.Cleanup()
+
+ ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
+ if err != nil {
+ t.Fatalf("NewEndpoint failed: %v", err)
+ }
+ c.EP = ep
+ if err := ep.Bind(tcpip.FullAddress{Addr: context.StackAddr, Port: context.StackPort}); err != nil {
+ t.Fatalf("Bind failed: %v", err)
+ }
+ if err := c.EP.Listen(1); err != nil {
+ t.Fatalf("Listen failed: %v", err)
+ }
+
+ stats := c.Stack().Stats()
+ want := stats.TCP.PassiveConnectionOpenings.Value() + 1
+
+ srcPort := uint16(context.TestPort)
+ executeHandshake(t, c, srcPort+1, false)
+
+ we, ch := waiter.NewChannelEntry(nil)
+ c.WQ.EventRegister(&we, waiter.EventIn)
+ defer c.WQ.EventUnregister(&we)
+
+ // Verify that there is only one acceptable connection at this point.
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ if got := stats.TCP.PassiveConnectionOpenings.Value(); got != want {
+ t.Errorf("got stats.TCP.PassiveConnectionOpenings.Value() = %v, want = %v", got, want)
+ }
+}
+
+func TestPassiveFailedConnectionAttemptIncrement(t *testing.T) {
+ c := context.New(t, defaultMTU)
+ defer c.Cleanup()
+
+ stats := c.Stack().Stats()
+ ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
+ if err != nil {
+ t.Fatalf("NewEndpoint failed: %v", err)
+ }
+ c.EP = ep
+ if err := c.EP.Bind(tcpip.FullAddress{Addr: context.StackAddr, Port: context.StackPort}); err != nil {
+ t.Fatalf("Bind failed: %v", err)
+ }
+ if err := c.EP.Listen(1); err != nil {
+ t.Fatalf("Listen failed: %v", err)
+ }
+
+ srcPort := uint16(context.TestPort)
+ // Now attempt 3 handshakes, the first two will fill up the accept and the SYN-RCVD
+ // queue for the endpoint.
+ executeHandshake(t, c, srcPort, false)
+
+ // Give time for the final ACK to be processed as otherwise the next handshake could
+ // get accepted before the previous one based on goroutine scheduling.
+ time.Sleep(50 * time.Millisecond)
+ irs, iss := executeHandshake(t, c, srcPort+1, false)
+
+ // Wait for a short while for the accepted connection to be delivered to
+ // the channel before trying to send the 3rd SYN.
+ time.Sleep(40 * time.Millisecond)
+
+ want := stats.TCP.ListenOverflowSynDrop.Value() + 1
+
+ // Now we will send one more SYN and this one should get dropped
+ // Send a SYN request.
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: srcPort + 2,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagSyn,
+ SeqNum: seqnum.Value(789),
+ RcvWnd: 30000,
+ })
+
+ time.Sleep(50 * time.Millisecond)
+ if got := stats.TCP.ListenOverflowSynDrop.Value(); got != want {
+ t.Errorf("got stats.TCP.ListenOverflowSynDrop.Value() = %v, want = %v", got, want)
+ }
+
+ we, ch := waiter.NewChannelEntry(nil)
+ c.WQ.EventRegister(&we, waiter.EventIn)
+ defer c.WQ.EventUnregister(&we)
+
+ // Now check that there is one acceptable connections.
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ // Now complete the next connection in SYN-RCVD state as it should
+ // have dropped the final ACK to the handshake due to accept queue
+ // being full.
+ c.SendPacket(nil, &context.Headers{
+ SrcPort: srcPort + 1,
+ DstPort: context.StackPort,
+ Flags: header.TCPFlagAck,
+ SeqNum: irs + 1,
+ AckNum: iss + 1,
+ RcvWnd: 30000,
+ })
+
+ // Now check that there is one more acceptable connections.
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ _, _, err = c.EP.Accept()
+ if err != nil {
+ t.Fatalf("Accept failed: %v", err)
+ }
+
+ case <-time.After(1 * time.Second):
+ t.Fatalf("Timed out waiting for accept")
+ }
+ }
+
+ // Try and accept a 3rd one this should fail.
+ _, _, err = c.EP.Accept()
+ if err == tcpip.ErrWouldBlock {
+ // Wait for connection to be established.
+ select {
+ case <-ch:
+ ep, _, err = c.EP.Accept()
+ if err == nil {
+ t.Fatalf("Accept succeeded when it should have failed got: %+v", ep)
+ }
+
+ case <-time.After(1 * time.Second):
+ }
+ }
+}
diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go
index e08eb6533..6e12413c6 100644
--- a/pkg/tcpip/transport/tcp/testing/context/context.go
+++ b/pkg/tcpip/transport/tcp/testing/context/context.go
@@ -989,3 +989,9 @@ func (c *Context) SACKEnabled() bool {
func (c *Context) SetGSOEnabled(enable bool) {
c.linkEP.GSO = enable
}
+
+// MSSWithoutOptions returns the value for the MSS used by the stack when no
+// options are in use.
+func (c *Context) MSSWithoutOptions() uint16 {
+ return uint16(c.linkEP.MTU() - header.IPv4MinimumSize - header.TCPMinimumSize)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 20:37:23 +0000