Ensure TCP TIME-WAIT is not terminated prematurely.

Netstack's TIME-WAIT state for a TCP socket could be terminated prematurely if
the socket entered TIME-WAIT using shutdown(..., SHUT_RDWR) and then was closed
using close(). This fixes that bug and updates the tests to verify that Netstack
correctly honors TIME-WAIT under such conditions.

Fixes #3106

PiperOrigin-RevId: 326456443

1 files changed, 24 insertions, 0 deletions

diff --git a/test/syscalls/linux/tcp_socket.cc b/test/syscalls/linux/tcp_socket.cc
index 0cea7d11f..a6325a761 100644
--- a/test/syscalls/linux/tcp_socket.cc
+++ b/test/syscalls/linux/tcp_socket.cc
@@ -720,6 +720,30 @@ TEST_P(TcpSocketTest, TcpSCMPriority) {
   ASSERT_EQ(cmsg, nullptr);
 }
 
+TEST_P(TcpSocketTest, TimeWaitPollHUP) {
+  shutdown(s_, SHUT_RDWR);
+  ScopedThread t([&]() {
+    constexpr int kTimeout = 10000;
+    constexpr int16_t want_events = POLLHUP;
+    struct pollfd pfd = {
+        .fd = s_,
+        .events = want_events,
+    };
+    ASSERT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1));
+  });
+  shutdown(t_, SHUT_RDWR);
+  t.Join();
+  // At this point s_ should be in TIME-WAIT and polling for POLLHUP should
+  // return with 1 FD.
+  constexpr int kTimeout = 10000;
+  constexpr int16_t want_events = POLLHUP;
+  struct pollfd pfd = {
+      .fd = s_,
+      .events = want_events,
+  };
+  ASSERT_THAT(poll(&pfd, 1, kTimeout), SyscallSucceedsWithValue(1));
+}
+
 INSTANTIATE_TEST_SUITE_P(AllInetTests, TcpSocketTest,
                          ::testing::Values(AF_INET, AF_INET6));