make sure not to return closed session from Listener.Accept()

integrationtests/self/handshake_test.go

@@ -147,23 +147,29 @@ var _ = Describe("Handshake tests", func() {
 	})
 
 	Context("rate limiting", func() {
-		It("rejects new connection attempts if connections don't get accepted", func() {
+		var server quic.Listener
+
+		dial := func() (quic.Session, error) {
+			return quic.DialAddr(
+				fmt.Sprintf("localhost:%d", server.Addr().(*net.UDPAddr).Port),
+				&tls.Config{RootCAs: testdata.GetRootCA()},
+				nil,
+			)
+		}
+
+		BeforeEach(func() {
+			serverConfig.AcceptCookie = func(net.Addr, *quic.Cookie) bool { return true }
+			var err error
 			// start the server, but don't call Accept
-			serverConfig.AcceptCookie = func(net.Addr, *quic.Cookie) bool {
-				return true
-			}
-			server, err := quic.ListenAddr("localhost:0", testdata.GetTLSConfig(), serverConfig)
+			server, err = quic.ListenAddr("localhost:0", testdata.GetTLSConfig(), serverConfig)
 			Expect(err).ToNot(HaveOccurred())
-			defer server.Close()
+		})
 
-			dial := func() (quic.Session, error) {
-				return quic.DialAddr(
-					fmt.Sprintf("localhost:%d", server.Addr().(*net.UDPAddr).Port),
-					&tls.Config{RootCAs: testdata.GetRootCA()},
-					nil,
-				)
-			}
+		AfterEach(func() {
+			Expect(server.Close()).To(Succeed())
+		})
 
+		It("rejects new connection attempts if connections don't get accepted", func() {
 			for i := 0; i < protocol.MaxAcceptQueueSize; i++ {
 				sess, err := dial()
 				Expect(err).ToNot(HaveOccurred())
@@ -171,7 +177,7 @@ var _ = Describe("Handshake tests", func() {
 			}
 			time.Sleep(25 * time.Millisecond) // wait a bit for the sessions to be queued
 
-			_, err = dial()
+			_, err := dial()
 			Expect(err).To(HaveOccurred())
 			// TODO(#1567): use the SERVER_BUSY error code
 			Expect(err.(*qerr.QuicError).ErrorCode).To(Equal(qerr.PeerGoingAway))
@@ -190,5 +196,37 @@ var _ = Describe("Handshake tests", func() {
 			// TODO(#1567): use the SERVER_BUSY error code
 			Expect(err.(*qerr.QuicError).ErrorCode).To(Equal(qerr.PeerGoingAway))
 		})
+
+		It("rejects new connection attempts if connections don't get accepted", func() {
+			firstSess, err := dial()
+			Expect(err).ToNot(HaveOccurred())
+
+			for i := 1; i < protocol.MaxAcceptQueueSize; i++ {
+				sess, err := dial()
+				Expect(err).ToNot(HaveOccurred())
+				defer sess.Close()
+			}
+			time.Sleep(25 * time.Millisecond) // wait a bit for the sessions to be queued
+
+			_, err = dial()
+			Expect(err).To(HaveOccurred())
+			// TODO(#1567): use the SERVER_BUSY error code
+			Expect(err.(*qerr.QuicError).ErrorCode).To(Equal(qerr.PeerGoingAway))
+
+			// Now close the one of the session that are waiting to be accepted.
+			// This should free one spot in the queue.
+			Expect(firstSess.Close())
+			time.Sleep(25 * time.Millisecond)
+
+			// dial again, and expect that this dial succeeds
+			_, err = dial()
+			Expect(err).ToNot(HaveOccurred())
+			time.Sleep(25 * time.Millisecond) // wait a bit for the session to be queued
+
+			_, err = dial()
+			// TODO(#1567): use the SERVER_BUSY error code
+			Expect(err.(*qerr.QuicError).ErrorCode).To(Equal(qerr.PeerGoingAway))
+		})
+
 	})
 })

server.go

@@ -170,8 +170,13 @@ func (s *server) setup() error {
 		onHandshakeCompleteImpl: func(sess Session) {
 			go func() {
 				atomic.AddInt32(&s.sessionQueueLen, 1)
-				s.sessionQueue <- sess // blocks until the session is accepted
-				atomic.AddInt32(&s.sessionQueueLen, -1)
+				defer atomic.AddInt32(&s.sessionQueueLen, -1)
+				select {
+				case s.sessionQueue <- sess:
+					// blocks until the session is accepted
+				case <-sess.Context().Done():
+					// don't pass sessions that were already closed to Accept()
+				}
 			}()
 		},
 		retireConnectionIDImpl: s.sessionHandler.Retire,

server_test.go

@@ -2,6 +2,7 @@ package quic
 
 import (
 	"bytes"
+	"context"
 	"crypto/tls"
 	"errors"
 	"net"
@@ -349,6 +350,7 @@ var _ = Describe("Server", func() {
 				sess := NewMockQuicSession(mockCtrl)
 				sess.EXPECT().handlePacket(p)
 				sess.EXPECT().run()
+				sess.EXPECT().Context().Return(context.Background())
 				runner.onHandshakeComplete(sess)
 				return sess, nil
 			}
@@ -375,6 +377,64 @@ var _ = Describe("Server", func() {
 			Expect(rejectHdr.DestConnectionID).To(Equal(hdr.SrcConnectionID))
 			Expect(rejectHdr.SrcConnectionID).To(Equal(hdr.DestConnectionID))
 		})
+
+		It("doesn't accept new sessions if they were closed in the mean time", func() {
+			serv.config.AcceptCookie = func(_ net.Addr, _ *Cookie) bool { return true }
+			senderAddr := &net.UDPAddr{IP: net.IPv4(1, 2, 3, 4), Port: 42}
+
+			hdr := &wire.Header{
+				Type:             protocol.PacketTypeInitial,
+				SrcConnectionID:  protocol.ConnectionID{5, 4, 3, 2, 1},
+				DestConnectionID: protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
+				Version:          protocol.VersionTLS,
+			}
+			p := &receivedPacket{
+				remoteAddr: senderAddr,
+				hdr:        hdr,
+				data:       bytes.Repeat([]byte{0}, protocol.MinInitialPacketSize),
+			}
+			ctx, cancel := context.WithCancel(context.Background())
+			sessionCreated := make(chan struct{})
+			sess := NewMockQuicSession(mockCtrl)
+			serv.newSession = func(
+				_ connection,
+				runner sessionRunner,
+				_ protocol.ConnectionID,
+				_ protocol.ConnectionID,
+				_ protocol.ConnectionID,
+				_ *Config,
+				_ *tls.Config,
+				_ *handshake.TransportParameters,
+				_ utils.Logger,
+				_ protocol.VersionNumber,
+			) (quicSession, error) {
+				sess.EXPECT().handlePacket(p)
+				sess.EXPECT().run()
+				sess.EXPECT().Context().Return(ctx)
+				runner.onHandshakeComplete(sess)
+				close(sessionCreated)
+				return sess, nil
+			}
+
+			serv.handlePacket(insertPacketBuffer(p))
+			Consistently(conn.dataWritten).ShouldNot(Receive())
+			Eventually(sessionCreated).Should(BeClosed())
+			cancel()
+			time.Sleep(scaleDuration(200 * time.Millisecond))
+
+			done := make(chan struct{})
+			go func() {
+				defer GinkgoRecover()
+				serv.Accept()
+				close(done)
+			}()
+			Consistently(done).ShouldNot(BeClosed())
+
+			// make the go routine return
+			sess.EXPECT().Close()
+			Expect(serv.Close()).To(Succeed())
+			Eventually(done).Should(BeClosed())
+		})
 	})
 
 	Context("accepting sessions", func() {
@@ -440,6 +500,7 @@ var _ = Describe("Server", func() {
 					runner.onHandshakeComplete(sess)
 				}()
 				sess.EXPECT().run().Do(func() {})
+				sess.EXPECT().Context().Return(context.Background())
 				return sess, nil
 			}
 			_, err := serv.createNewSession(&net.UDPAddr{}, nil, nil, nil, nil, protocol.VersionWhatever)
@@ -466,8 +527,9 @@ var _ = Describe("Server", func() {
 				_ protocol.VersionNumber,
 			) (quicSession, error) {
 				sess := NewMockQuicSession(mockCtrl)
-				runner.onHandshakeComplete(sess)
 				sess.EXPECT().run().Do(func() {})
+				sess.EXPECT().Context().Return(context.Background())
+				runner.onHandshakeComplete(sess)
 				done <- struct{}{}
 				return sess, nil
 			}