tcp: Add selftest for bind() and TIME_WAIT.

bhash2 split the bind() validation logic into wildcard and non-wildcard
cases.  Let's add a test to catch future regression.

Before the previous patch:

  # ./bind_timewait
  TAP version 13
  1..2
  # Starting 2 tests from 3 test cases.
  #  RUN           bind_timewait.localhost.1 ...
  # bind_timewait.c:87:1:Expected ret (0) == -1 (-1)
  # 1: Test terminated by assertion
  #          FAIL  bind_timewait.localhost.1
  not ok 1 bind_timewait.localhost.1
  #  RUN           bind_timewait.addrany.1 ...
  #            OK  bind_timewait.addrany.1
  ok 2 bind_timewait.addrany.1
  # FAILED: 1 / 2 tests passed.
  # Totals: pass:1 fail:1 xfail:0 xpass:0 skip:0 error:0

After:

  # ./bind_timewait
  TAP version 13
  1..2
  # Starting 2 tests from 3 test cases.
  #  RUN           bind_timewait.localhost.1 ...
  #            OK  bind_timewait.localhost.1
  ok 1 bind_timewait.localhost.1
  #  RUN           bind_timewait.addrany.1 ...
  #            OK  bind_timewait.addrany.1
  ok 2 bind_timewait.addrany.1
  # PASSED: 2 / 2 tests passed.
  # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
 bind_bhash
+bind_timewait
 csum
 cmsg_sender
 diag_uid

tools/testing/selftests/net/bind_timewait.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Amazon.com Inc. or its affiliates. */
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include "../kselftest_harness.h"
+
+FIXTURE(bind_timewait)
+{
+	struct sockaddr_in addr;
+	socklen_t addrlen;
+};
+
+FIXTURE_VARIANT(bind_timewait)
+{
+	__u32 addr_const;
+};
+
+FIXTURE_VARIANT_ADD(bind_timewait, localhost)
+{
+	.addr_const = INADDR_LOOPBACK
+};
+
+FIXTURE_VARIANT_ADD(bind_timewait, addrany)
+{
+	.addr_const = INADDR_ANY
+};
+
+FIXTURE_SETUP(bind_timewait)
+{
+	self->addr.sin_family = AF_INET;
+	self->addr.sin_port = 0;
+	self->addr.sin_addr.s_addr = htonl(variant->addr_const);
+	self->addrlen = sizeof(self->addr);
+}
+
+FIXTURE_TEARDOWN(bind_timewait)
+{
+}
+
+void create_timewait_socket(struct __test_metadata *_metadata,
+			    FIXTURE_DATA(bind_timewait) *self)
+{
+	int server_fd, client_fd, child_fd, ret;
+	struct sockaddr_in addr;
+	socklen_t addrlen;
+
+	server_fd = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GT(server_fd, 0);
+
+	ret = bind(server_fd, (struct sockaddr *)&self->addr, self->addrlen);
+	ASSERT_EQ(ret, 0);
+
+	ret = listen(server_fd, 1);
+	ASSERT_EQ(ret, 0);
+
+	ret = getsockname(server_fd, (struct sockaddr *)&self->addr, &self->addrlen);
+	ASSERT_EQ(ret, 0);
+
+	client_fd = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GT(client_fd, 0);
+
+	ret = connect(client_fd, (struct sockaddr *)&self->addr, self->addrlen);
+	ASSERT_EQ(ret, 0);
+
+	addrlen = sizeof(addr);
+	child_fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen);
+	ASSERT_GT(child_fd, 0);
+
+	close(child_fd);
+	close(client_fd);
+	close(server_fd);
+}
+
+TEST_F(bind_timewait, 1)
+{
+	int fd, ret;
+
+	create_timewait_socket(_metadata, self);
+
+	fd = socket(AF_INET, SOCK_STREAM, 0);
+	ASSERT_GT(fd, 0);
+
+	ret = bind(fd, (struct sockaddr *)&self->addr, self->addrlen);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EADDRINUSE);
+
+	close(fd);
+}
+
+TEST_HARNESS_MAIN