diff options
Diffstat (limited to 'test')
| -rw-r--r-- | test/packetimpact/runner/defs.bzl | 6 | ||||
| -rw-r--r-- | test/packetimpact/tests/BUILD | 20 | ||||
| -rw-r--r-- | test/packetimpact/tests/tcp_listen_backlog_test.go | 86 | ||||
| -rw-r--r-- | test/packetimpact/tests/tcp_syncookie_test.go | 70 | ||||
| -rw-r--r-- | test/syscalls/linux/socket_inet_loopback.cc | 334 |
5 files changed, 394 insertions, 122 deletions
diff --git a/test/packetimpact/runner/defs.bzl b/test/packetimpact/runner/defs.bzl index 34e83ec49..634c15727 100644 --- a/test/packetimpact/runner/defs.bzl +++ b/test/packetimpact/runner/defs.bzl @@ -246,6 +246,12 @@ ALL_TESTS = [ expect_netstack_failure = True, ), PacketimpactTestInfo( + name = "tcp_listen_backlog", + ), + PacketimpactTestInfo( + name = "tcp_syncookie", + ), + PacketimpactTestInfo( name = "icmpv6_param_problem", ), PacketimpactTestInfo( diff --git a/test/packetimpact/tests/BUILD b/test/packetimpact/tests/BUILD index 92103c1e9..83ff70951 100644 --- a/test/packetimpact/tests/BUILD +++ b/test/packetimpact/tests/BUILD @@ -385,6 +385,26 @@ packetimpact_testbench( ], ) +packetimpact_testbench( + name = "tcp_listen_backlog", + srcs = ["tcp_listen_backlog_test.go"], + deps = [ + "//pkg/tcpip/header", + "//test/packetimpact/testbench", + "@org_golang_x_sys//unix:go_default_library", + ], +) + +packetimpact_testbench( + name = "tcp_syncookie", + srcs = ["tcp_syncookie_test.go"], + deps = [ + "//pkg/tcpip/header", + "//test/packetimpact/testbench", + "@org_golang_x_sys//unix:go_default_library", + ], +) + validate_all_tests() [packetimpact_go_test( diff --git a/test/packetimpact/tests/tcp_listen_backlog_test.go b/test/packetimpact/tests/tcp_listen_backlog_test.go new file mode 100644 index 000000000..26c812d0a --- /dev/null +++ b/test/packetimpact/tests/tcp_listen_backlog_test.go @@ -0,0 +1,86 @@ +// Copyright 2021 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package tcp_listen_backlog_test + +import ( + "flag" + "testing" + "time" + + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/pkg/tcpip/header" + "gvisor.dev/gvisor/test/packetimpact/testbench" +) + +func init() { + testbench.Initialize(flag.CommandLine) +} + +// TestTCPListenBacklog tests for a listening endpoint behavior: +// (1) reply to more SYNs than what is configured as listen backlog +// (2) ignore ACKs (that complete a handshake) when the accept queue is full +// (3) ignore incoming SYNs when the accept queue is full +func TestTCPListenBacklog(t *testing.T) { + dut := testbench.NewDUT(t) + + // Listening endpoint accepts one more connection than the listen backlog. + listenFd, remotePort := dut.CreateListener(t, unix.SOCK_STREAM, unix.IPPROTO_TCP, 0 /*backlog*/) + + var establishedConn testbench.TCPIPv4 + var incompleteConn testbench.TCPIPv4 + + // Test if the DUT listener replies to more SYNs than listen backlog+1 + for i, conn := range []*testbench.TCPIPv4{&establishedConn, &incompleteConn} { + *conn = dut.Net.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort}) + // Expect dut connection to have transitioned to SYN-RCVD state. + conn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn)}) + if _, err := conn.ExpectData(t, &testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn | header.TCPFlagAck)}, nil, time.Second); err != nil { + t.Fatalf("expected SYN-ACK for %d connection, %s", i, err) + } + } + defer establishedConn.Close(t) + defer incompleteConn.Close(t) + + // Send the ACK to complete handshake. + establishedConn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck)}) + dut.PollOne(t, listenFd, unix.POLLIN, time.Second) + + // Send the ACK to complete handshake, expect this to be ignored by the + // listener. + incompleteConn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck)}) + + // Drain the accept queue to enable poll for subsequent connections on the + // listener. + dut.Accept(t, listenFd) + + // The ACK for the incomplete connection should be ignored by the + // listening endpoint and the poll on listener should now time out. + if pfds := dut.Poll(t, []unix.PollFd{{Fd: listenFd, Events: unix.POLLIN}}, time.Second); len(pfds) != 0 { + t.Fatalf("got dut.Poll(...) = %#v", pfds) + } + + // Re-send the ACK to complete handshake and re-fill the accept-queue. + incompleteConn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagAck)}) + dut.PollOne(t, listenFd, unix.POLLIN, time.Second) + + // Now initiate a new connection when the accept queue is full. + connectingConn := dut.Net.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort}) + defer connectingConn.Close(t) + // Expect dut connection to drop the SYN and let the client stay in SYN_SENT state. + connectingConn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn)}) + if got, err := connectingConn.ExpectData(t, &testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn | header.TCPFlagAck)}, nil, time.Second); err == nil { + t.Fatalf("expected no SYN-ACK, but got %s", got) + } +} diff --git a/test/packetimpact/tests/tcp_syncookie_test.go b/test/packetimpact/tests/tcp_syncookie_test.go new file mode 100644 index 000000000..1c21c62ff --- /dev/null +++ b/test/packetimpact/tests/tcp_syncookie_test.go @@ -0,0 +1,70 @@ +// Copyright 2021 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package tcp_syncookie_test + +import ( + "flag" + "testing" + "time" + + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/pkg/tcpip/header" + "gvisor.dev/gvisor/test/packetimpact/testbench" +) + +func init() { + testbench.Initialize(flag.CommandLine) +} + +// TestSynCookie test if the DUT listener is replying back using syn cookies. +// The test does not complete the handshake by not sending the ACK to SYNACK. +// When syncookies are not used, this forces the listener to retransmit SYNACK. +// And when syncookies are being used, there is no such retransmit. +func TestTCPSynCookie(t *testing.T) { + dut := testbench.NewDUT(t) + + // Listening endpoint accepts one more connection than the listen backlog. + _, remotePort := dut.CreateListener(t, unix.SOCK_STREAM, unix.IPPROTO_TCP, 1 /*backlog*/) + + var withoutSynCookieConn testbench.TCPIPv4 + var withSynCookieConn testbench.TCPIPv4 + + // Test if the DUT listener replies to more SYNs than listen backlog+1 + for _, conn := range []*testbench.TCPIPv4{&withoutSynCookieConn, &withSynCookieConn} { + *conn = dut.Net.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort}) + } + defer withoutSynCookieConn.Close(t) + defer withSynCookieConn.Close(t) + + checkSynAck := func(t *testing.T, conn *testbench.TCPIPv4, expectRetransmit bool) { + // Expect dut connection to have transitioned to SYN-RCVD state. + conn.Send(t, testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn)}) + if _, err := conn.ExpectData(t, &testbench.TCP{Flags: testbench.TCPFlags(header.TCPFlagSyn | header.TCPFlagAck)}, nil, time.Second); err != nil { + t.Fatalf("expected SYN-ACK, but got %s", err) + } + + // If the DUT listener is using syn cookies, it will not retransmit SYNACK + got, err := conn.ExpectData(t, &testbench.TCP{SeqNum: testbench.Uint32(uint32(*conn.RemoteSeqNum(t) - 1)), Flags: testbench.TCPFlags(header.TCPFlagSyn | header.TCPFlagAck)}, nil, 2*time.Second) + if expectRetransmit && err != nil { + t.Fatalf("expected retransmitted SYN-ACK, but got %s", err) + } + if !expectRetransmit && err == nil { + t.Fatalf("expected no retransmitted SYN-ACK, but got %s", got) + } + } + + t.Run("without syncookies", func(t *testing.T) { checkSynAck(t, &withoutSynCookieConn, true /*expectRetransmit*/) }) + t.Run("with syncookies", func(t *testing.T) { checkSynAck(t, &withSynCookieConn, false /*expectRetransmit*/) }) +} diff --git a/test/syscalls/linux/socket_inet_loopback.cc b/test/syscalls/linux/socket_inet_loopback.cc index 597b5bcb1..d391363fb 100644 --- a/test/syscalls/linux/socket_inet_loopback.cc +++ b/test/syscalls/linux/socket_inet_loopback.cc @@ -489,13 +489,6 @@ void TestListenWhileConnect(const TestParam& param, TestAddress const& listener = param.listener; TestAddress const& connector = param.connector; - constexpr int kBacklog = 2; - // Linux completes one more connection than the listen backlog argument. - // To ensure that there is at least one client connection that stays in - // connecting state, keep 2 more client connections than the listen backlog. - // gVisor differs in this behavior though, gvisor.dev/issue/3153. - constexpr int kClients = kBacklog + 2; - // Create the listening socket. FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE( Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP)); @@ -503,6 +496,13 @@ void TestListenWhileConnect(const TestParam& param, ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr), listener.addr_len), SyscallSucceeds()); + // This test is only interested in deterministically getting a socket in + // connecting state. For that, we use a listen backlog of zero which would + // mean there is exactly one connection that gets established and is enqueued + // to the accept queue. We poll on the listener to ensure that is enqueued. + // After that the subsequent client connect will stay in connecting state as + // the accept queue is full. + constexpr int kBacklog = 0; ASSERT_THAT(listen(listen_fd.get(), kBacklog), SyscallSucceeds()); // Get the port bound by the listening socket. @@ -515,42 +515,49 @@ void TestListenWhileConnect(const TestParam& param, sockaddr_storage conn_addr = connector.addr; ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port)); - std::vector<FileDescriptor> clients; - for (int i = 0; i < kClients; i++) { - FileDescriptor client = ASSERT_NO_ERRNO_AND_VALUE( - Socket(connector.family(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP)); - int ret = connect(client.get(), reinterpret_cast<sockaddr*>(&conn_addr), - connector.addr_len); - if (ret != 0) { - EXPECT_THAT(ret, SyscallFailsWithErrno(EINPROGRESS)); - clients.push_back(std::move(client)); - } + FileDescriptor established_client = ASSERT_NO_ERRNO_AND_VALUE( + Socket(connector.family(), SOCK_STREAM, IPPROTO_TCP)); + ASSERT_THAT( + connect(established_client.get(), reinterpret_cast<sockaddr*>(&conn_addr), + connector.addr_len), + SyscallSucceeds()); + + // Ensure that the accept queue has the completed connection. + constexpr int kTimeout = 10000; + pollfd pfd = { + .fd = listen_fd.get(), + .events = POLLIN, + }; + ASSERT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1)); + ASSERT_EQ(pfd.revents, POLLIN); + + FileDescriptor connecting_client = ASSERT_NO_ERRNO_AND_VALUE( + Socket(connector.family(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP)); + // Keep the last client in connecting state. + int ret = + connect(connecting_client.get(), reinterpret_cast<sockaddr*>(&conn_addr), + connector.addr_len); + if (ret != 0) { + EXPECT_THAT(ret, SyscallFailsWithErrno(EINPROGRESS)); } stopListen(listen_fd); - for (auto& client : clients) { - constexpr int kTimeout = 10000; + std::array<std::pair<int, int>, 2> sockets = { + std::make_pair(established_client.get(), ECONNRESET), + std::make_pair(connecting_client.get(), ECONNREFUSED), + }; + for (size_t i = 0; i < sockets.size(); i++) { + SCOPED_TRACE(absl::StrCat("i=", i)); + auto [fd, expected_errno] = sockets[i]; pollfd pfd = { - .fd = client.get(), - .events = POLLIN, + .fd = fd, }; - // When the listening socket is closed, then we expect the remote to reset - // the connection. - ASSERT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1)); - ASSERT_EQ(pfd.revents, POLLIN | POLLHUP | POLLERR); + // When the listening socket is closed, the peer would reset the connection. + EXPECT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1)); + EXPECT_EQ(pfd.revents, POLLHUP | POLLERR); char c; - // Subsequent read can fail with: - // ECONNRESET: If the client connection was established and was reset by the - // remote. - // ECONNREFUSED: If the client connection failed to be established. - ASSERT_THAT(read(client.get(), &c, sizeof(c)), - AnyOf(SyscallFailsWithErrno(ECONNRESET), - SyscallFailsWithErrno(ECONNREFUSED))); - // The last client connection would be in connecting (SYN_SENT) state. - if (client.get() == clients[kClients - 1].get()) { - ASSERT_EQ(errno, ECONNREFUSED) << strerror(errno); - } + EXPECT_THAT(read(fd, &c, sizeof(c)), SyscallFailsWithErrno(expected_errno)); } } @@ -570,7 +577,59 @@ TEST_P(SocketInetLoopbackTest, TCPListenShutdownWhileConnect) { // random save as established connections which can't be delivered to the accept // queue because the queue is full are not correctly delivered after restore // causing the last accept to timeout on the restore. -TEST_P(SocketInetLoopbackTest, TCPbacklog_NoRandomSave) { +TEST_P(SocketInetLoopbackTest, TCPAcceptBacklogSizes_NoRandomSave) { + auto const& param = GetParam(); + + TestAddress const& listener = param.listener; + TestAddress const& connector = param.connector; + + // Create the listening socket. + const FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE( + Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP)); + sockaddr_storage listen_addr = listener.addr; + ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr), + listener.addr_len), + SyscallSucceeds()); + // Get the port bound by the listening socket. + socklen_t addrlen = listener.addr_len; + ASSERT_THAT(getsockname(listen_fd.get(), + reinterpret_cast<sockaddr*>(&listen_addr), &addrlen), + SyscallSucceeds()); + uint16_t const port = + ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr)); + std::array<int, 3> backlogs = {-1, 0, 1}; + for (auto& backlog : backlogs) { + ASSERT_THAT(listen(listen_fd.get(), backlog), SyscallSucceeds()); + + int expected_accepts; + if (backlog < 0) { + expected_accepts = 1024; + } else { + expected_accepts = backlog + 1; + } + for (int i = 0; i < expected_accepts; i++) { + SCOPED_TRACE(absl::StrCat("i=", i)); + // Connect to the listening socket. + const FileDescriptor conn_fd = ASSERT_NO_ERRNO_AND_VALUE( + Socket(connector.family(), SOCK_STREAM, IPPROTO_TCP)); + sockaddr_storage conn_addr = connector.addr; + ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port)); + ASSERT_THAT( + RetryEINTR(connect)(conn_fd.get(), + reinterpret_cast<struct sockaddr*>(&conn_addr), + connector.addr_len), + SyscallSucceeds()); + const FileDescriptor accepted = + ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr)); + } + } +} + +// TODO(b/157236388): Remove _NoRandomSave once bug is fixed. Test fails w/ +// random save as established connections which can't be delivered to the accept +// queue because the queue is full are not correctly delivered after restore +// causing the last accept to timeout on the restore. +TEST_P(SocketInetLoopbackTest, TCPBacklog_NoRandomSave) { auto const& param = GetParam(); TestAddress const& listener = param.listener; @@ -595,6 +654,7 @@ TEST_P(SocketInetLoopbackTest, TCPbacklog_NoRandomSave) { ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr)); int i = 0; while (1) { + SCOPED_TRACE(absl::StrCat("i=", i)); int ret; // Connect to the listening socket. @@ -620,103 +680,133 @@ TEST_P(SocketInetLoopbackTest, TCPbacklog_NoRandomSave) { i++; } + int client_conns = i; + int accepted_conns = 0; for (; i != 0; i--) { - // Accept the connection. - // - // We have to assign a name to the accepted socket, as unamed temporary - // objects are destructed upon full evaluation of the expression it is in, - // potentially causing the connecting socket to fail to shutdown properly. - auto accepted = - ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr)); + SCOPED_TRACE(absl::StrCat("i=", i)); + pollfd pfd = { + .fd = listen_fd.get(), + .events = POLLIN, + }; + // Look for incoming connections to accept. The last connect request could + // be established from the client side, but the ACK of the handshake could + // be dropped by the listener if the accept queue was filled up by the + // previous connect. + int ret; + ASSERT_THAT(ret = poll(&pfd, 1, 3000), SyscallSucceeds()); + if (ret == 0) break; + if (pfd.revents == POLLIN) { + // Accept the connection. + // + // We have to assign a name to the accepted socket, as unamed temporary + // objects are destructed upon full evaluation of the expression it is in, + // potentially causing the connecting socket to fail to shutdown properly. + auto accepted = + ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr)); + accepted_conns++; + } } + // We should accept at least listen backlog + 1 connections. As the stack is + // enqueuing established connections to the accept queue, newer SYNs could + // still be replied to causing those client connections would be accepted as + // we start dequeuing the queue. + ASSERT_GE(accepted_conns, kBacklogSize + 1); + ASSERT_GE(client_conns, accepted_conns); } -// Test if the stack completes atmost listen backlog number of client -// connections. It exercises the path of the stack that enqueues completed -// connections to accept queue vs new incoming SYNs. -TEST_P(SocketInetLoopbackTest, TCPConnectBacklog_NoRandomSave) { - const auto& param = GetParam(); - const TestAddress& listener = param.listener; - const TestAddress& connector = param.connector; +// TODO(b/157236388): Remove _NoRandomSave once bug is fixed. Test fails w/ +// random save as established connections which can't be delivered to the accept +// queue because the queue is full are not correctly delivered after restore +// causing the last accept to timeout on the restore. +TEST_P(SocketInetLoopbackTest, TCPBacklogAcceptAll_NoRandomSave) { + auto const& param = GetParam(); + TestAddress const& listener = param.listener; + TestAddress const& connector = param.connector; + // Create the listening socket. + FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE( + Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP)); + sockaddr_storage listen_addr = listener.addr; + ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr), + listener.addr_len), + SyscallSucceeds()); constexpr int kBacklog = 1; - // Keep the number of client connections more than the listen backlog. - // Linux completes one more connection than the listen backlog argument. - // gVisor differs in this behavior though, gvisor.dev/issue/3153. - int kClients = kBacklog + 2; - if (IsRunningOnGvisor()) { - kClients--; - } + ASSERT_THAT(listen(listen_fd.get(), kBacklog), SyscallSucceeds()); - // Run the following test for few iterations to test race between accept queue - // getting filled with incoming SYNs. - for (int num = 0; num < 10; num++) { - FileDescriptor listen_fd = ASSERT_NO_ERRNO_AND_VALUE( - Socket(listener.family(), SOCK_STREAM, IPPROTO_TCP)); - sockaddr_storage listen_addr = listener.addr; - ASSERT_THAT(bind(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr), - listener.addr_len), - SyscallSucceeds()); - ASSERT_THAT(listen(listen_fd.get(), kBacklog), SyscallSucceeds()); + // Get the port bound by the listening socket. + socklen_t addrlen = listener.addr_len; + ASSERT_THAT(getsockname(listen_fd.get(), + reinterpret_cast<sockaddr*>(&listen_addr), &addrlen), + SyscallSucceeds()); + uint16_t const port = + ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr)); - socklen_t addrlen = listener.addr_len; - ASSERT_THAT( - getsockname(listen_fd.get(), reinterpret_cast<sockaddr*>(&listen_addr), - &addrlen), - SyscallSucceeds()); - uint16_t const port = - ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr)); - sockaddr_storage conn_addr = connector.addr; - ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port)); + sockaddr_storage conn_addr = connector.addr; + ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port)); - std::vector<FileDescriptor> clients; - // Issue multiple non-blocking client connects. - for (int i = 0; i < kClients; i++) { - FileDescriptor client = ASSERT_NO_ERRNO_AND_VALUE( - Socket(connector.family(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP)); - int ret = connect(client.get(), reinterpret_cast<sockaddr*>(&conn_addr), - connector.addr_len); - if (ret != 0) { - EXPECT_THAT(ret, SyscallFailsWithErrno(EINPROGRESS)); - } - clients.push_back(std::move(client)); + // Fill up the accept queue and trigger more client connections which would be + // waiting to be accepted. + std::array<FileDescriptor, kBacklog + 1> established_clients; + for (auto& fd : established_clients) { + fd = ASSERT_NO_ERRNO_AND_VALUE( + Socket(connector.family(), SOCK_STREAM, IPPROTO_TCP)); + ASSERT_THAT(connect(fd.get(), reinterpret_cast<sockaddr*>(&conn_addr), + connector.addr_len), + SyscallSucceeds()); + } + std::array<FileDescriptor, kBacklog> waiting_clients; + for (auto& fd : waiting_clients) { + fd = ASSERT_NO_ERRNO_AND_VALUE( + Socket(connector.family(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP)); + int ret = connect(fd.get(), reinterpret_cast<sockaddr*>(&conn_addr), + connector.addr_len); + if (ret != 0) { + EXPECT_THAT(ret, SyscallFailsWithErrno(EINPROGRESS)); } + } - // Now that client connects are issued, wait for the accept queue to get - // filled and ensure no new client connection is completed. - for (int i = 0; i < kClients; i++) { - pollfd pfd = { - .fd = clients[i].get(), - .events = POLLOUT, - }; - if (i < kClients - 1) { - // Poll for client side connection completions with a large timeout. - // We cannot poll on the listener side without calling accept as poll - // stays level triggered with non-zero accept queue length. - // - // Client side poll would not guarantee that the completed connection - // has been enqueued in to the acccept queue, but the fact that the - // listener ACKd the SYN, means that it cannot complete any new incoming - // SYNs when it has already ACKd for > backlog number of SYNs. - ASSERT_THAT(poll(&pfd, 1, 10000), SyscallSucceedsWithValue(1)) - << "num=" << num << " i=" << i << " kClients=" << kClients; - ASSERT_EQ(pfd.revents, POLLOUT) << "num=" << num << " i=" << i; - } else { - // Now that we expect accept queue filled up, ensure that the last - // client connection never completes with a smaller poll timeout. - ASSERT_THAT(poll(&pfd, 1, 1000), SyscallSucceedsWithValue(0)) - << "num=" << num << " i=" << i; - } + auto accept_connection = [&]() { + constexpr int kTimeout = 10000; + pollfd pfd = { + .fd = listen_fd.get(), + .events = POLLIN, + }; + ASSERT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1)); + ASSERT_EQ(pfd.revents, POLLIN); + // Accept the connection. + // + // We have to assign a name to the accepted socket, as unamed temporary + // objects are destructed upon full evaluation of the expression it is in, + // potentially causing the connecting socket to fail to shutdown properly. + auto accepted = + ASSERT_NO_ERRNO_AND_VALUE(Accept(listen_fd.get(), nullptr, nullptr)); + }; - ASSERT_THAT(close(clients[i].release()), SyscallSucceedsWithValue(0)) - << "num=" << num << " i=" << i; - } - clients.clear(); - // We close the listening side and open a new listener. We could instead - // drain the accept queue by calling accept() and reuse the listener, but - // that is racy as the retransmitted SYNs could get ACKd as we make room in - // the accept queue. - ASSERT_THAT(close(listen_fd.release()), SyscallSucceedsWithValue(0)); + // Ensure that we accept all client connections. The waiting connections would + // get enqueued as we drain the accept queue. + for (int i = 0; i < std::size(established_clients); i++) { + SCOPED_TRACE(absl::StrCat("established clients i=", i)); + accept_connection(); + } + + // The waiting client connections could be in one of these 2 states: + // (1) SYN_SENT: if the SYN was dropped because accept queue was full + // (2) ESTABLISHED: if the listener sent back a SYNACK, but may have dropped + // the ACK from the client if the accept queue was full (send out a data to + // re-send that ACK, to address that case). + for (int i = 0; i < std::size(waiting_clients); i++) { + SCOPED_TRACE(absl::StrCat("waiting clients i=", i)); + constexpr int kTimeout = 10000; + pollfd pfd = { + .fd = waiting_clients[i].get(), + .events = POLLOUT, + }; + EXPECT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1)); + EXPECT_EQ(pfd.revents, POLLOUT); + char c; + EXPECT_THAT(RetryEINTR(send)(waiting_clients[i].get(), &c, sizeof(c), 0), + SyscallSucceedsWithValue(sizeof(c))); + accept_connection(); } } |