From 35ea47c6fc85a90d6507b8fad1a515dbcd7e3d88 Mon Sep 17 00:00:00 2001
From: gVisor bot <gvisor-bot@google.com>
Date: Fri, 20 May 2022 13:39:36 -0700
Subject: [PATCH] Add test for SO_REUSEPORT and SO_BINDTODEVICE together

Check that when two sockets are bound to the same device and have SO_REUSEPORT
set, they can both be bound to the same address. This test provides missing
coverage for when the two socket options are set together.

Bug: https://fxbug.dev/97822
PiperOrigin-RevId: 450053747
---
 test/syscalls/linux/socket_inet_loopback.cc | 39 +++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/test/syscalls/linux/socket_inet_loopback.cc b/test/syscalls/linux/socket_inet_loopback.cc
index 0ba88735f..e7a3cac62 100644
--- a/test/syscalls/linux/socket_inet_loopback.cc
+++ b/test/syscalls/linux/socket_inet_loopback.cc
@@ -2471,6 +2471,45 @@ TEST_P(SocketMultiProtocolInetLoopbackTest, PortReuseTwoSockets) {
   }
 }
 
+TEST_P(SocketMultiProtocolInetLoopbackTest, BindToDeviceReusePort) {
+  ProtocolTestParam const& param = GetParam();
+  TestAddress const& test_addr = V4Loopback();
+
+  auto socket1 =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(test_addr.family(), param.type, 0));
+  auto socket2 =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(test_addr.family(), param.type, 0));
+
+  const char kLoopbackDeviceName[] = "lo";
+
+  // Bind socket1 with REUSEPORT and BINDTODEVICE.
+  ASSERT_THAT(setsockopt(socket1.get(), SOL_SOCKET, SO_REUSEPORT, &kSockOptOn,
+                         sizeof(kSockOptOn)),
+              SyscallSucceeds());
+  ASSERT_THAT(setsockopt(socket1.get(), SOL_SOCKET, SO_BINDTODEVICE,
+                         kLoopbackDeviceName, strlen(kLoopbackDeviceName)),
+              SyscallSucceeds());
+
+  // Bind the first socket to the loopback and take note of the selected port.
+  auto addr = V4Loopback();
+  ASSERT_THAT(bind(socket1.get(), AsSockAddr(&addr.addr), addr.addr_len),
+              SyscallSucceeds());
+  socklen_t addr_len = addr.addr_len;
+  ASSERT_THAT(getsockname(socket1.get(), AsSockAddr(&addr.addr), &addr_len),
+              SyscallSucceeds());
+  EXPECT_EQ(addr_len, addr.addr_len);
+
+  // Bind socket2 to the same device and address as socket1.
+  ASSERT_THAT(setsockopt(socket2.get(), SOL_SOCKET, SO_BINDTODEVICE,
+                         kLoopbackDeviceName, strlen(kLoopbackDeviceName)),
+              SyscallSucceeds());
+  ASSERT_THAT(setsockopt(socket2.get(), SOL_SOCKET, SO_REUSEPORT, &kSockOptOn,
+                         sizeof(kSockOptOn)),
+              SyscallSucceeds());
+  ASSERT_THAT(bind(socket2.get(), AsSockAddr(&addr.addr), addr.addr_len),
+              SyscallSucceeds());
+}
+
 // Check that when a socket was bound to an address with REUSEPORT and then
 // closed, we can bind a different socket to the same address without needing
 // REUSEPORT.