Open source system call tests.

PiperOrigin-RevId: 224886231
Change-Id: I0fccb4d994601739d8b16b1d4e6b31f40297fb22

1 files changed, 759 insertions, 0 deletions

diff --git a/test/syscalls/linux/tcp_socket.cc b/test/syscalls/linux/tcp_socket.cc
new file mode 100644
index 000000000..e6fe84ded
--- /dev/null
+++ b/test/syscalls/linux/tcp_socket.cc
@@ -0,0 +1,759 @@
+// Copyright 2018 Google LLC
+//
+// 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.
+
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sys/poll.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <limits>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+#include "test/syscalls/linux/socket_test_util.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/posix_error.h"
+#include "test/util/test_util.h"
+#include "test/util/thread_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+PosixErrorOr<sockaddr_storage> InetLoopbackAddr(int family) {
+  struct sockaddr_storage addr;
+  memset(&addr, 0, sizeof(addr));
+  addr.ss_family = family;
+  switch (family) {
+    case AF_INET:
+      reinterpret_cast<struct sockaddr_in*>(&addr)->sin_addr.s_addr =
+          htonl(INADDR_LOOPBACK);
+      break;
+    case AF_INET6:
+      reinterpret_cast<struct sockaddr_in6*>(&addr)->sin6_addr =
+          in6addr_loopback;
+      break;
+    default:
+      return PosixError(EINVAL,
+                        absl::StrCat("unknown socket family: ", family));
+  }
+  return addr;
+}
+
+// Fixture for tests parameterized by the address family to use (AF_INET and
+// AF_INET6) when creating sockets.
+class TcpSocketTest : public ::testing::TestWithParam<int> {
+ protected:
+  // Creates three sockets that will be used by test cases -- a listener, one
+  // that connects, and the accepted one.
+  void SetUp() override;
+
+  // Closes the sockets created by SetUp().
+  void TearDown() override;
+
+  // Listening socket.
+  int listener_ = -1;
+
+  // Socket connected via connect().
+  int s_ = -1;
+
+  // Socket connected via accept().
+  int t_ = -1;
+
+  // Initial size of the send buffer.
+  int sendbuf_size_ = -1;
+};
+
+void TcpSocketTest::SetUp() {
+  ASSERT_THAT(listener_ = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+
+  ASSERT_THAT(s_ = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+
+  // Initialize address to the loopback one.
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  socklen_t addrlen = sizeof(addr);
+
+  // Bind to some port then start listening.
+  ASSERT_THAT(
+      bind(listener_, reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+      SyscallSucceeds());
+
+  ASSERT_THAT(listen(listener_, SOMAXCONN), SyscallSucceeds());
+
+  // Get the address we're listening on, then connect to it. We need to do this
+  // because we're allowing the stack to pick a port for us.
+  ASSERT_THAT(getsockname(listener_, reinterpret_cast<struct sockaddr*>(&addr),
+                          &addrlen),
+              SyscallSucceeds());
+
+  ASSERT_THAT(RetryEINTR(connect)(s_, reinterpret_cast<struct sockaddr*>(&addr),
+                                  addrlen),
+              SyscallSucceeds());
+
+  // Get the initial send buffer size.
+  socklen_t optlen = sizeof(sendbuf_size_);
+  ASSERT_THAT(getsockopt(s_, SOL_SOCKET, SO_SNDBUF, &sendbuf_size_, &optlen),
+              SyscallSucceeds());
+
+  // Accept the connection.
+  ASSERT_THAT(t_ = RetryEINTR(accept)(listener_, nullptr, nullptr),
+              SyscallSucceeds());
+}
+
+void TcpSocketTest::TearDown() {
+  EXPECT_THAT(close(listener_), SyscallSucceeds());
+  if (s_ >= 0) {
+    EXPECT_THAT(close(s_), SyscallSucceeds());
+  }
+  if (t_ >= 0) {
+    EXPECT_THAT(close(t_), SyscallSucceeds());
+  }
+}
+
+TEST_P(TcpSocketTest, DataCoalesced) {
+  char buf[10];
+
+  // Write in two steps.
+  ASSERT_THAT(RetryEINTR(write)(s_, buf, sizeof(buf) / 2),
+              SyscallSucceedsWithValue(sizeof(buf) / 2));
+  ASSERT_THAT(RetryEINTR(write)(s_, buf, sizeof(buf) / 2),
+              SyscallSucceedsWithValue(sizeof(buf) / 2));
+
+  // Allow stack to process both packets.
+  absl::SleepFor(absl::Seconds(1));
+
+  // Read in one shot.
+  EXPECT_THAT(RetryEINTR(recv)(t_, buf, sizeof(buf), 0),
+              SyscallSucceedsWithValue(sizeof(buf)));
+}
+
+TEST_P(TcpSocketTest, SenderAddressIgnored) {
+  char buf[3];
+  ASSERT_THAT(RetryEINTR(write)(s_, buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  struct sockaddr_storage addr;
+  socklen_t addrlen = sizeof(addr);
+  memset(&addr, 0, sizeof(addr));
+
+  ASSERT_THAT(
+      RetryEINTR(recvfrom)(t_, buf, sizeof(buf), 0,
+                           reinterpret_cast<struct sockaddr*>(&addr), &addrlen),
+      SyscallSucceedsWithValue(3));
+
+  // Check that addr remains zeroed-out.
+  const char* ptr = reinterpret_cast<char*>(&addr);
+  for (size_t i = 0; i < sizeof(addr); i++) {
+    EXPECT_EQ(ptr[i], 0);
+  }
+}
+
+TEST_P(TcpSocketTest, SenderAddressIgnoredOnPeek) {
+  char buf[3];
+  ASSERT_THAT(RetryEINTR(write)(s_, buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  struct sockaddr_storage addr;
+  socklen_t addrlen = sizeof(addr);
+  memset(&addr, 0, sizeof(addr));
+
+  ASSERT_THAT(
+      RetryEINTR(recvfrom)(t_, buf, sizeof(buf), MSG_PEEK,
+                           reinterpret_cast<struct sockaddr*>(&addr), &addrlen),
+      SyscallSucceedsWithValue(3));
+
+  // Check that addr remains zeroed-out.
+  const char* ptr = reinterpret_cast<char*>(&addr);
+  for (size_t i = 0; i < sizeof(addr); i++) {
+    EXPECT_EQ(ptr[i], 0);
+  }
+}
+
+TEST_P(TcpSocketTest, SendtoAddressIgnored) {
+  struct sockaddr_storage addr;
+  memset(&addr, 0, sizeof(addr));
+  addr.ss_family = GetParam();  // FIXME
+
+  char data = '\0';
+  EXPECT_THAT(
+      RetryEINTR(sendto)(s_, &data, sizeof(data), 0,
+                         reinterpret_cast<sockaddr*>(&addr), sizeof(addr)),
+      SyscallSucceedsWithValue(1));
+}
+
+TEST_P(TcpSocketTest, WritevZeroIovec) {
+  // 2 bytes just to be safe and have vecs[1] not point to something random
+  // (even though length is 0).
+  char buf[2];
+  char recv_buf[1];
+
+  // Construct a vec where the final vector is of length 0.
+  iovec vecs[2] = {};
+  vecs[0].iov_base = buf;
+  vecs[0].iov_len = 1;
+  vecs[1].iov_base = buf + 1;
+  vecs[1].iov_len = 0;
+
+  EXPECT_THAT(RetryEINTR(writev)(s_, vecs, 2), SyscallSucceedsWithValue(1));
+
+  EXPECT_THAT(RetryEINTR(recv)(t_, recv_buf, 1, 0),
+              SyscallSucceedsWithValue(1));
+  EXPECT_EQ(memcmp(recv_buf, buf, 1), 0);
+}
+
+TEST_P(TcpSocketTest, ZeroWriteAllowed) {
+  char buf[3];
+  // Send a zero length packet.
+  ASSERT_THAT(RetryEINTR(write)(s_, buf, 0), SyscallSucceedsWithValue(0));
+  // Verify that there is no packet available.
+  EXPECT_THAT(RetryEINTR(recv)(t_, buf, sizeof(buf), MSG_DONTWAIT),
+              SyscallFailsWithErrno(EAGAIN));
+}
+
+// Test that a non-blocking write with a buffer that is larger than the send
+// buffer size will not actually write the whole thing at once.
+TEST_P(TcpSocketTest, NonblockingLargeWrite) {
+  // Set the FD to O_NONBLOCK.
+  int opts;
+  ASSERT_THAT(opts = fcntl(s_, F_GETFL), SyscallSucceeds());
+  opts |= O_NONBLOCK;
+  ASSERT_THAT(fcntl(s_, F_SETFL, opts), SyscallSucceeds());
+
+  // Allocate a buffer three times the size of the send buffer. We do this with
+  // a vector to avoid allocating on the stack.
+  int size = 3 * sendbuf_size_;
+  std::vector<char> buf(size);
+
+  // Try to write the whole thing.
+  int n;
+  ASSERT_THAT(n = RetryEINTR(write)(s_, buf.data(), size), SyscallSucceeds());
+
+  // We should have written something, but not the whole thing.
+  EXPECT_GT(n, 0);
+  EXPECT_LT(n, size);
+}
+
+// Test that a blocking write with a buffer that is larger than the send buffer
+// will block until the entire buffer is sent.
+TEST_P(TcpSocketTest, BlockingLargeWrite_NoRandomSave) {
+  // Allocate a buffer three times the size of the send buffer on the heap. We
+  // do this as a vector to avoid allocating on the stack.
+  int size = 3 * sendbuf_size_;
+  std::vector<char> writebuf(size);
+
+  // Start reading the response in a loop.
+  int read_bytes = 0;
+  ScopedThread t([this, &read_bytes]() {
+    // Avoid interrupting the blocking write in main thread.
+    const DisableSave ds;
+    char readbuf[2500] = {};
+    int n = -1;
+    while (n != 0) {
+      EXPECT_THAT(n = RetryEINTR(read)(t_, &readbuf, sizeof(readbuf)),
+                  SyscallSucceeds());
+      read_bytes += n;
+    }
+  });
+
+  // Try to write the whole thing.
+  int n;
+  ASSERT_THAT(n = WriteFd(s_, writebuf.data(), size), SyscallSucceeds());
+
+  // We should have written the whole thing.
+  EXPECT_EQ(n, size);
+  EXPECT_THAT(close(s_), SyscallSucceedsWithValue(0));
+  s_ = -1;
+  t.Join();
+
+  // We should have read the whole thing.
+  EXPECT_EQ(read_bytes, size);
+}
+
+// Test that a send with MSG_DONTWAIT flag and buffer that larger than the send
+// buffer size will not write the whole thing.
+TEST_P(TcpSocketTest, LargeSendDontWait) {
+  // Allocate a buffer three times the size of the send buffer. We do this on
+  // with a vector to avoid allocating on the stack.
+  int size = 3 * sendbuf_size_;
+  std::vector<char> buf(size);
+
+  // Try to write the whole thing with MSG_DONTWAIT flag, which can
+  // return a partial write.
+  int n;
+  ASSERT_THAT(n = RetryEINTR(send)(s_, buf.data(), size, MSG_DONTWAIT),
+              SyscallSucceeds());
+
+  // We should have written something, but not the whole thing.
+  EXPECT_GT(n, 0);
+  EXPECT_LT(n, size);
+}
+
+// Test that a send on a non-blocking socket with a buffer that larger than the
+// send buffer will not write the whole thing at once.
+TEST_P(TcpSocketTest, NonblockingLargeSend) {
+  // Set the FD to O_NONBLOCK.
+  int opts;
+  ASSERT_THAT(opts = fcntl(s_, F_GETFL), SyscallSucceeds());
+  opts |= O_NONBLOCK;
+  ASSERT_THAT(fcntl(s_, F_SETFL, opts), SyscallSucceeds());
+
+  // Allocate a buffer three times the size of the send buffer. We do this on
+  // with a vector to avoid allocating on the stack.
+  int size = 3 * sendbuf_size_;
+  std::vector<char> buf(size);
+
+  // Try to write the whole thing.
+  int n;
+  ASSERT_THAT(n = RetryEINTR(send)(s_, buf.data(), size, 0), SyscallSucceeds());
+
+  // We should have written something, but not the whole thing.
+  EXPECT_GT(n, 0);
+  EXPECT_LT(n, size);
+}
+
+// Same test as above, but calls send instead of write.
+TEST_P(TcpSocketTest, BlockingLargeSend_NoRandomSave) {
+  // Allocate a buffer three times the size of the send buffer. We do this on
+  // with a vector to avoid allocating on the stack.
+  int size = 3 * sendbuf_size_;
+  std::vector<char> writebuf(size);
+
+  // Start reading the response in a loop.
+  int read_bytes = 0;
+  ScopedThread t([this, &read_bytes]() {
+    // Avoid interrupting the blocking write in main thread.
+    const DisableSave ds;
+    char readbuf[2500] = {};
+    int n = -1;
+    while (n != 0) {
+      EXPECT_THAT(n = RetryEINTR(read)(t_, &readbuf, sizeof(readbuf)),
+                  SyscallSucceeds());
+      read_bytes += n;
+    }
+  });
+
+  // Try to send the whole thing.
+  int n;
+  ASSERT_THAT(n = SendFd(s_, writebuf.data(), size, 0), SyscallSucceeds());
+
+  // We should have written the whole thing.
+  EXPECT_EQ(n, size);
+  EXPECT_THAT(close(s_), SyscallSucceedsWithValue(0));
+  s_ = -1;
+  t.Join();
+
+  // We should have read the whole thing.
+  EXPECT_EQ(read_bytes, size);
+}
+
+// Test that polling on a socket with a full send buffer will block.
+TEST_P(TcpSocketTest, PollWithFullBufferBlocks) {
+  // Set the FD to O_NONBLOCK.
+  int opts;
+  ASSERT_THAT(opts = fcntl(s_, F_GETFL), SyscallSucceeds());
+  opts |= O_NONBLOCK;
+  ASSERT_THAT(fcntl(s_, F_SETFL, opts), SyscallSucceeds());
+
+  // Set TCP_NODELAY, which will cause linux to fill the receive buffer from the
+  // send buffer as quickly as possibly. This way we can fill up both buffers
+  // faster.
+  constexpr int tcp_nodelay_flag = 1;
+  ASSERT_THAT(setsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &tcp_nodelay_flag,
+                         sizeof(tcp_nodelay_flag)),
+              SyscallSucceeds());
+
+  // Create a large buffer that will be used for sending.
+  std::vector<char> buf(5 * sendbuf_size_);
+
+  // Write until we receive an error.
+  while (RetryEINTR(send)(s_, buf.data(), buf.size(), 0) != -1) {
+    // Sleep to give linux a chance to move data from the send buffer to the
+    // receive buffer.
+    usleep(10000);  // 10ms.
+  }
+  // The last error should have been EWOULDBLOCK.
+  ASSERT_EQ(errno, EWOULDBLOCK);
+}
+
+TEST_P(TcpSocketTest, MsgTrunc) {
+  char sent_data[512];
+  RandomizeBuffer(sent_data, sizeof(sent_data));
+  ASSERT_THAT(RetryEINTR(send)(s_, sent_data, sizeof(sent_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  char received_data[sizeof(sent_data)] = {};
+  ASSERT_THAT(
+      RetryEINTR(recv)(t_, received_data, sizeof(received_data) / 2, MSG_TRUNC),
+      SyscallSucceedsWithValue(sizeof(sent_data) / 2));
+
+  // Check that we didn't get anything.
+  char zeros[sizeof(received_data)] = {};
+  EXPECT_EQ(0, memcmp(zeros, received_data, sizeof(received_data)));
+}
+
+// MSG_CTRUNC is a return flag but linux allows it to be set on input flags
+// without returning an error.
+TEST_P(TcpSocketTest, MsgTruncWithCtrunc) {
+  char sent_data[512];
+  RandomizeBuffer(sent_data, sizeof(sent_data));
+  ASSERT_THAT(RetryEINTR(send)(s_, sent_data, sizeof(sent_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  char received_data[sizeof(sent_data)] = {};
+  ASSERT_THAT(RetryEINTR(recv)(t_, received_data, sizeof(received_data) / 2,
+                               MSG_TRUNC | MSG_CTRUNC),
+              SyscallSucceedsWithValue(sizeof(sent_data) / 2));
+
+  // Check that we didn't get anything.
+  char zeros[sizeof(received_data)] = {};
+  EXPECT_EQ(0, memcmp(zeros, received_data, sizeof(received_data)));
+}
+
+// This test will verify that MSG_CTRUNC doesn't do anything when specified
+// on input.
+TEST_P(TcpSocketTest, MsgTruncWithCtruncOnly) {
+  char sent_data[512];
+  RandomizeBuffer(sent_data, sizeof(sent_data));
+  ASSERT_THAT(RetryEINTR(send)(s_, sent_data, sizeof(sent_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  char received_data[sizeof(sent_data)] = {};
+  ASSERT_THAT(RetryEINTR(recv)(t_, received_data, sizeof(received_data) / 2,
+                               MSG_CTRUNC),
+              SyscallSucceedsWithValue(sizeof(sent_data) / 2));
+
+  // Since MSG_CTRUNC here had no affect, it should not behave like MSG_TRUNC.
+  EXPECT_EQ(0, memcmp(sent_data, received_data, sizeof(sent_data) / 2));
+}
+
+TEST_P(TcpSocketTest, MsgTruncLargeSize) {
+  char sent_data[512];
+  RandomizeBuffer(sent_data, sizeof(sent_data));
+  ASSERT_THAT(RetryEINTR(send)(s_, sent_data, sizeof(sent_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  char received_data[sizeof(sent_data) * 2] = {};
+  ASSERT_THAT(
+      RetryEINTR(recv)(t_, received_data, sizeof(received_data), MSG_TRUNC),
+      SyscallSucceedsWithValue(sizeof(sent_data)));
+
+  // Check that we didn't get anything.
+  char zeros[sizeof(received_data)] = {};
+  EXPECT_EQ(0, memcmp(zeros, received_data, sizeof(received_data)));
+}
+
+TEST_P(TcpSocketTest, MsgTruncPeek) {
+  char sent_data[512];
+  RandomizeBuffer(sent_data, sizeof(sent_data));
+  ASSERT_THAT(RetryEINTR(send)(s_, sent_data, sizeof(sent_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  char received_data[sizeof(sent_data)] = {};
+  ASSERT_THAT(RetryEINTR(recv)(t_, received_data, sizeof(received_data) / 2,
+                               MSG_TRUNC | MSG_PEEK),
+              SyscallSucceedsWithValue(sizeof(sent_data) / 2));
+
+  // Check that we didn't get anything.
+  char zeros[sizeof(received_data)] = {};
+  EXPECT_EQ(0, memcmp(zeros, received_data, sizeof(received_data)));
+
+  // Check that we can still get all of the data.
+  ASSERT_THAT(RetryEINTR(recv)(t_, received_data, sizeof(received_data), 0),
+              SyscallSucceedsWithValue(sizeof(sent_data)));
+  EXPECT_EQ(0, memcmp(sent_data, received_data, sizeof(sent_data)));
+}
+
+TEST_P(TcpSocketTest, NoDelayDefault) {
+  int get = -1;
+  socklen_t get_len = sizeof(get);
+  EXPECT_THAT(getsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &get, &get_len),
+              SyscallSucceedsWithValue(0));
+  EXPECT_EQ(get_len, sizeof(get));
+  EXPECT_EQ(get, kSockOptOff);
+}
+
+TEST_P(TcpSocketTest, SetNoDelay) {
+  ASSERT_THAT(
+      setsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &kSockOptOn, sizeof(kSockOptOn)),
+      SyscallSucceeds());
+
+  int get = -1;
+  socklen_t get_len = sizeof(get);
+  EXPECT_THAT(getsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &get, &get_len),
+              SyscallSucceedsWithValue(0));
+  EXPECT_EQ(get_len, sizeof(get));
+  EXPECT_EQ(get, kSockOptOn);
+
+  ASSERT_THAT(setsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &kSockOptOff,
+                         sizeof(kSockOptOff)),
+              SyscallSucceeds());
+
+  EXPECT_THAT(getsockopt(s_, IPPROTO_TCP, TCP_NODELAY, &get, &get_len),
+              SyscallSucceedsWithValue(0));
+  EXPECT_EQ(get_len, sizeof(get));
+  EXPECT_EQ(get, kSockOptOff);
+}
+
+INSTANTIATE_TEST_CASE_P(AllInetTests, TcpSocketTest,
+                        ::testing::Values(AF_INET, AF_INET6));
+
+// Fixture for tests parameterized by address family that don't want the fixture
+// to do things.
+using SimpleTcpSocketTest = ::testing::TestWithParam<int>;
+
+TEST_P(SimpleTcpSocketTest, SendUnconnected) {
+  int fd;
+  ASSERT_THAT(fd = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+  FileDescriptor sock_fd(fd);
+
+  char data = '\0';
+  EXPECT_THAT(RetryEINTR(send)(fd, &data, sizeof(data), 0),
+              SyscallFailsWithErrno(EPIPE));
+}
+
+TEST_P(SimpleTcpSocketTest, SendtoWithoutAddressUnconnected) {
+  int fd;
+  ASSERT_THAT(fd = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+  FileDescriptor sock_fd(fd);
+
+  char data = '\0';
+  EXPECT_THAT(RetryEINTR(sendto)(fd, &data, sizeof(data), 0, nullptr, 0),
+              SyscallFailsWithErrno(EPIPE));
+}
+
+TEST_P(SimpleTcpSocketTest, SendtoWithAddressUnconnected) {
+  int fd;
+  ASSERT_THAT(fd = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+  FileDescriptor sock_fd(fd);
+
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  char data = '\0';
+  EXPECT_THAT(
+      RetryEINTR(sendto)(fd, &data, sizeof(data), 0,
+                         reinterpret_cast<sockaddr*>(&addr), sizeof(addr)),
+      SyscallFailsWithErrno(EPIPE));
+}
+
+TEST_P(SimpleTcpSocketTest, GetPeerNameUnconnected) {
+  int fd;
+  ASSERT_THAT(fd = socket(GetParam(), SOCK_STREAM, IPPROTO_TCP),
+              SyscallSucceeds());
+  FileDescriptor sock_fd(fd);
+
+  sockaddr_storage addr;
+  socklen_t addrlen = sizeof(addr);
+  EXPECT_THAT(getpeername(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen),
+              SyscallFailsWithErrno(ENOTCONN));
+}
+
+TEST_P(TcpSocketTest, FullBuffer) {
+  // Set both FDs to be blocking.
+  int flags = 0;
+  ASSERT_THAT(flags = fcntl(s_, F_GETFL), SyscallSucceeds());
+  EXPECT_THAT(fcntl(s_, F_SETFL, flags & ~O_NONBLOCK), SyscallSucceeds());
+  flags = 0;
+  ASSERT_THAT(flags = fcntl(t_, F_GETFL), SyscallSucceeds());
+  EXPECT_THAT(fcntl(t_, F_SETFL, flags & ~O_NONBLOCK), SyscallSucceeds());
+
+  // 2500 was chosen as a small value that can be set on Linux.
+  int set_snd = 2500;
+  EXPECT_THAT(setsockopt(s_, SOL_SOCKET, SO_SNDBUF, &set_snd, sizeof(set_snd)),
+              SyscallSucceedsWithValue(0));
+  int get_snd = -1;
+  socklen_t get_snd_len = sizeof(get_snd);
+  EXPECT_THAT(getsockopt(s_, SOL_SOCKET, SO_SNDBUF, &get_snd, &get_snd_len),
+              SyscallSucceedsWithValue(0));
+  EXPECT_EQ(get_snd_len, sizeof(get_snd));
+  EXPECT_GT(get_snd, 0);
+
+  // 2500 was chosen as a small value that can be set on Linux and gVisor.
+  int set_rcv = 2500;
+  EXPECT_THAT(setsockopt(t_, SOL_SOCKET, SO_RCVBUF, &set_rcv, sizeof(set_rcv)),
+              SyscallSucceedsWithValue(0));
+  int get_rcv = -1;
+  socklen_t get_rcv_len = sizeof(get_rcv);
+  EXPECT_THAT(getsockopt(t_, SOL_SOCKET, SO_RCVBUF, &get_rcv, &get_rcv_len),
+              SyscallSucceedsWithValue(0));
+  EXPECT_EQ(get_rcv_len, sizeof(get_rcv));
+  EXPECT_GE(get_rcv, 2500);
+
+  // Quick sanity test.
+  EXPECT_LT(get_snd + get_rcv, 2500 * IOV_MAX);
+
+  char data[2500] = {};
+  std::vector<struct iovec> iovecs;
+  for (int i = 0; i < IOV_MAX; i++) {
+    struct iovec iov = {};
+    iov.iov_base = data;
+    iov.iov_len = sizeof(data);
+    iovecs.push_back(iov);
+  }
+  ScopedThread t([this, &iovecs]() {
+    int result = -1;
+    EXPECT_THAT(result = RetryEINTR(writev)(s_, iovecs.data(), iovecs.size()),
+                SyscallSucceeds());
+    EXPECT_GT(result, 1);
+    EXPECT_LT(result, sizeof(data) * iovecs.size());
+  });
+
+  char recv = 0;
+  EXPECT_THAT(RetryEINTR(read)(t_, &recv, 1), SyscallSucceedsWithValue(1));
+  EXPECT_THAT(close(t_), SyscallSucceedsWithValue(0));
+  t_ = -1;
+}
+
+TEST_P(SimpleTcpSocketTest, NonBlockingConnectNoListener) {
+  // Initialize address to the loopback one.
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  socklen_t addrlen = sizeof(addr);
+
+  const FileDescriptor s =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(GetParam(), SOCK_STREAM, IPPROTO_TCP));
+
+  // Set the FD to O_NONBLOCK.
+  int opts;
+  ASSERT_THAT(opts = fcntl(s.get(), F_GETFL), SyscallSucceeds());
+  opts |= O_NONBLOCK;
+  ASSERT_THAT(fcntl(s.get(), F_SETFL, opts), SyscallSucceeds());
+
+  ASSERT_THAT(RetryEINTR(connect)(
+                  s.get(), reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+              SyscallFailsWithErrno(EINPROGRESS));
+
+  // Now polling on the FD with a timeout should return 0 corresponding to no
+  // FDs ready.
+  struct pollfd poll_fd = {s.get(), POLLOUT, 0};
+  EXPECT_THAT(RetryEINTR(poll)(&poll_fd, 1, 10000),
+              SyscallSucceedsWithValue(1));
+
+  int err;
+  socklen_t optlen = sizeof(err);
+  ASSERT_THAT(getsockopt(s.get(), SOL_SOCKET, SO_ERROR, &err, &optlen),
+              SyscallSucceeds());
+
+  EXPECT_EQ(err, ECONNREFUSED);
+}
+
+TEST_P(SimpleTcpSocketTest, NonBlockingConnect) {
+  const FileDescriptor listener =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(GetParam(), SOCK_STREAM, IPPROTO_TCP));
+
+  // Initialize address to the loopback one.
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  socklen_t addrlen = sizeof(addr);
+
+  // Bind to some port then start listening.
+  ASSERT_THAT(
+      bind(listener.get(), reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+      SyscallSucceeds());
+
+  ASSERT_THAT(listen(listener.get(), SOMAXCONN), SyscallSucceeds());
+
+  FileDescriptor s =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(GetParam(), SOCK_STREAM, IPPROTO_TCP));
+
+  // Set the FD to O_NONBLOCK.
+  int opts;
+  ASSERT_THAT(opts = fcntl(s.get(), F_GETFL), SyscallSucceeds());
+  opts |= O_NONBLOCK;
+  ASSERT_THAT(fcntl(s.get(), F_SETFL, opts), SyscallSucceeds());
+
+  ASSERT_THAT(getsockname(listener.get(),
+                          reinterpret_cast<struct sockaddr*>(&addr), &addrlen),
+              SyscallSucceeds());
+
+  ASSERT_THAT(RetryEINTR(connect)(
+                  s.get(), reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+              SyscallFailsWithErrno(EINPROGRESS));
+
+  int t;
+  ASSERT_THAT(t = RetryEINTR(accept)(listener.get(), nullptr, nullptr),
+              SyscallSucceeds());
+
+  // Now polling on the FD with a timeout should return 0 corresponding to no
+  // FDs ready.
+  struct pollfd poll_fd = {s.get(), POLLOUT, 0};
+  EXPECT_THAT(RetryEINTR(poll)(&poll_fd, 1, 10000),
+              SyscallSucceedsWithValue(1));
+
+  int err;
+  socklen_t optlen = sizeof(err);
+  ASSERT_THAT(getsockopt(s.get(), SOL_SOCKET, SO_ERROR, &err, &optlen),
+              SyscallSucceeds());
+
+  EXPECT_EQ(err, 0);
+
+  EXPECT_THAT(close(t), SyscallSucceeds());
+}
+
+// Test that we get an ECONNREFUSED with a blocking socket when no one is
+// listening on the other end.
+TEST_P(SimpleTcpSocketTest, BlockingConnectRefused) {
+  FileDescriptor s =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(GetParam(), SOCK_STREAM, IPPROTO_TCP));
+
+  // Initialize address to the loopback one.
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  socklen_t addrlen = sizeof(addr);
+
+  ASSERT_THAT(RetryEINTR(connect)(
+                  s.get(), reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+              SyscallFailsWithErrno(ECONNREFUSED));
+
+  // Avoiding triggering save in destructor of s.
+  EXPECT_THAT(close(s.release()), SyscallSucceeds());
+}
+
+// Test that we get an ECONNREFUSED with a nonblocking socket.
+TEST_P(SimpleTcpSocketTest, NonBlockingConnectRefused) {
+  FileDescriptor s = ASSERT_NO_ERRNO_AND_VALUE(
+      Socket(GetParam(), SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP));
+
+  // Initialize address to the loopback one.
+  sockaddr_storage addr =
+      ASSERT_NO_ERRNO_AND_VALUE(InetLoopbackAddr(GetParam()));
+  socklen_t addrlen = sizeof(addr);
+
+  ASSERT_THAT(RetryEINTR(connect)(
+                  s.get(), reinterpret_cast<struct sockaddr*>(&addr), addrlen),
+              SyscallFailsWithErrno(EINPROGRESS));
+
+  // We don't need to specify any events to get POLLHUP or POLLERR as these
+  // are added before the poll.
+  struct pollfd poll_fd = {s.get(), /*events=*/0, 0};
+  EXPECT_THAT(RetryEINTR(poll)(&poll_fd, 1, 1000), SyscallSucceedsWithValue(1));
+
+  // The ECONNREFUSED should cause us to be woken up with POLLHUP.
+  EXPECT_NE(poll_fd.revents & (POLLHUP | POLLERR), 0);
+
+  // Avoiding triggering save in destructor of s.
+  EXPECT_THAT(close(s.release()), SyscallSucceeds());
+}
+
+INSTANTIATE_TEST_CASE_P(AllInetTests, SimpleTcpSocketTest,
+                        ::testing::Values(AF_INET, AF_INET6));
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor