Add initial version

The initial version implements the basic functionality
of the client/server communication and lease management.

For now, one lease is created per valid connector (dependent
on CRTC availablity).

Bug-AGL: SPEC-3729

Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Change-Id: I2b37a892742cc22bdc53a5172c8ad3d8a7bb5e66

9 files changed, 823 insertions, 0 deletions

diff --git a/libdlmclient/dlmclient.c b/libdlmclient/dlmclient.c
new file mode 100644
index 0000000..32493d3
--- /dev/null
+++ b/libdlmclient/dlmclient.c
@@ -0,0 +1,170 @@
+/* Copyright 2020-2021 IGEL Co., Ltd.
+ *
+ * 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 "dlmclient.h"
+#include "log.h"
+#include "socket-path.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+void dlm_enable_debug_log(bool enable)
+{
+	dlm_log_enable_debug(enable);
+}
+
+struct dlm_lease {
+	int dlm_server_sock;
+	int lease_fd;
+};
+
+static bool lease_connect(struct dlm_lease *lease, const char *name)
+{
+	struct sockaddr_un sa = {
+	    .sun_family = AF_UNIX,
+	};
+
+	if (!sockaddr_set_lease_server_path(&sa, name))
+		return false;
+
+	int dlm_server_sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (dlm_server_sock < 0) {
+		DEBUG_LOG("Socket creation failed: %s\n", strerror(errno));
+		return false;
+	}
+
+	while (connect(dlm_server_sock, (struct sockaddr *)&sa,
+		       sizeof(struct sockaddr_un)) == -1) {
+		if (errno == EINTR)
+			continue;
+		DEBUG_LOG("Cannot connect to %s: %s\n", sa.sun_path,
+			  strerror(errno));
+		close(dlm_server_sock);
+		return false;
+	}
+	lease->dlm_server_sock = dlm_server_sock;
+	return true;
+}
+
+static bool lease_recv_fd(struct dlm_lease *lease)
+{
+	char ctrl_buf[CMSG_SPACE(sizeof(int))] = {0};
+	char data[1] = {0};
+
+	struct iovec iov[1];
+	iov[0].iov_base = data;
+	iov[0].iov_len = sizeof(data);
+
+	struct msghdr msg = {
+	    .msg_control = ctrl_buf,
+	    .msg_controllen = CMSG_SPACE(sizeof(int)),
+	    .msg_iov = iov,
+	    .msg_iovlen = 1,
+	};
+
+	int ret;
+	while ((ret = recvmsg(lease->dlm_server_sock, &msg, 0)) <= 0) {
+		if (ret == 0) {
+			errno = EACCES;
+			DEBUG_LOG("Request rejected by DRM lease manager\n");
+			// TODO: Report why the request was rejected.
+			return false;
+		}
+		if (errno != EINTR) {
+			DEBUG_LOG("Socket data receive error: %s\n",
+				  strerror(errno));
+			return false;
+		}
+	}
+
+	lease->lease_fd = -1;
+	struct cmsghdr *cmsg;
+	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
+	     cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+		if (cmsg->cmsg_level == SOL_SOCKET &&
+		    cmsg->cmsg_type == SCM_RIGHTS) {
+			int nfds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+			int *fds = (int *)CMSG_DATA(cmsg);
+
+			if (nfds == 1) {
+				lease->lease_fd = fds[0];
+				break;
+			}
+
+			DEBUG_LOG(
+			    "Expected 1 fd from lease manager. Received %d\n",
+			    nfds);
+			/* Close any unexpected fds so we don't leak them. */
+			for (int i = 0; i < nfds; i++)
+				close(fds[i]);
+			break;
+		}
+	}
+
+	if (lease->lease_fd < 0) {
+		DEBUG_LOG("Expected data not received from lease manager\n");
+		errno = EPROTO;
+		return false;
+	}
+
+	return true;
+}
+
+struct dlm_lease *dlm_get_lease(const char *name)
+{
+	struct dlm_lease *lease = calloc(1, sizeof(struct dlm_lease));
+	if (!lease) {
+		DEBUG_LOG("can't allocate memory : %s\n", strerror(errno));
+		return NULL;
+	}
+
+	if (!lease_connect(lease, name)) {
+		free(lease);
+		return NULL;
+	}
+
+	if (!lease_recv_fd(lease)) {
+		close(lease->dlm_server_sock);
+		free(lease);
+		return NULL;
+	}
+
+	return lease;
+}
+
+void dlm_release_lease(struct dlm_lease *lease)
+{
+	if (!lease)
+		return;
+
+	close(lease->lease_fd);
+	close(lease->dlm_server_sock);
+	free(lease);
+}
+
+int dlm_lease_fd(struct dlm_lease *lease)
+{
+	if (!lease)
+		return -1;
+
+	return lease->lease_fd;
+}
diff --git a/libdlmclient/dlmclient.h b/libdlmclient/dlmclient.h
new file mode 100644
index 0000000..908cd6b
--- /dev/null
+++ b/libdlmclient/dlmclient.h
@@ -0,0 +1,86 @@
+/* Copyright 2020-2021 IGEL Co., Ltd.
+ *
+ * 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.
+ */
+
+/**
+ * @file dlmclient.h
+ */
+#ifndef DLM_CLIENT_H
+#define DLM_CLIENT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+
+/**
+ * @brief Enable debug logging
+ *
+ * @param[in] enable enable/disable debug logging
+ */
+void dlm_enable_debug_log(bool enable);
+
+/**
+ * @brief lease handle
+ */
+struct dlm_lease;
+
+/**
+ * @brief  Get a DRM lease from the lease manager
+ *
+ * @param[in] name requested lease
+ * @return A pointer to a lease handle on success.
+ *         On error this function returns NULL and errno is set accordingly.
+ *
+ *  Possible errors:
+ *
+ *  errno        |  Meaning
+ *  -------------|-------------------------------------------------------------
+ *  EACCESS      |  Cannot access lease manager socket directory
+ *  EACCESS      |  Lease request denied by lease manager
+ *  ENAMETOOLONG |  The path to the lease manager socket directory is too long
+ *  ENOENT       |  Lease manager or requested lease not available
+ *  ENOMEM       |  Out of memory during operation
+ *  EPROTO       |  Protocol error in communication with lease manager
+ *
+ *  This list is not exhaustive, and errno may be set to other error codes,
+ *  especially those related to socket communication.
+ */
+struct dlm_lease *dlm_get_lease(const char *name);
+
+/**
+ * @brief  Release a lease handle
+ *
+ * @details Release a lease handle.  The lease handle will be invalidated and
+ *          the associated DRM lease wil be revoked.  Any fd's retrieved from
+ *          dlm_lease_fd() will be closed.
+ * @param[in] lease pointer to lease handle
+ */
+void dlm_release_lease(struct dlm_lease *lease);
+
+/**
+ * @brief Get a DRM Master fd from a valid lease handle
+ *
+ * @param[in] lease pointer to a lease handle
+ * @return A DRM Master file descriptor for the lease on success.
+ *         -1 is returned when called with a NULL lease handle.
+ */
+int dlm_lease_fd(struct dlm_lease *lease);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/libdlmclient/docs/Doxyfile.in b/libdlmclient/docs/Doxyfile.in
new file mode 100644
index 0000000..dce4244
--- /dev/null
+++ b/libdlmclient/docs/Doxyfile.in
@@ -0,0 +1,9 @@
+# General information
+PROJECT_NAME = "DRM Lease Manager Client Library"
+OUTPUT_DIRECTORY = @DOXYGEN_OUTPUT@
+INPUT = @README@ @CLIENT_HEADER_DIR@
+USE_MDFILE_AS_MAINPAGE = @README@
+FILE_PATTERNS = *.h
+GENERATE_LATEX = NO
+OPTIMIZE_OUTPUT_FOR_C = YES
+STRIP_FROM_PATH    = @CLIENT_HEADER_DIR@
diff --git a/libdlmclient/docs/meson.build b/libdlmclient/docs/meson.build
new file mode 100644
index 0000000..563e5fb
--- /dev/null
+++ b/libdlmclient/docs/meson.build
@@ -0,0 +1,21 @@
+doxygen = find_program('doxygen', required : false)
+
+readme = join_paths(meson.source_root(), 'README.md')
+
+if get_option('enable-docs') and doxygen.found()
+    conf_data = configuration_data()
+    conf_data.set('README', readme)
+    conf_data.set('CLIENT_HEADER_DIR', dlmclient_header_dir)
+    conf_data.set('DOXYGEN_OUTPUT', meson.current_build_dir())
+    doxyfile = configure_file(
+        input: 'Doxyfile.in',
+        output: 'Doxyfile',
+        configuration: conf_data
+    )
+    custom_target('docs',
+      input: [doxyfile, readme, dlmclient_headers],
+      build_by_default: true,
+      command: [doxygen, '@INPUT0@'],
+      output: ['html']
+    )
+endif
diff --git a/libdlmclient/meson.build b/libdlmclient/meson.build
new file mode 100644
index 0000000..d63a842
--- /dev/null
+++ b/libdlmclient/meson.build
@@ -0,0 +1,38 @@
+dlmclient_sources = files(
+    'dlmclient.c'
+)
+
+dlmclient_headers = files(
+    'dlmclient.h'
+)
+
+libdlmclient = library(
+    'dlmclient',
+    sources: dlmclient_sources,
+    version: meson.project_version(),
+    dependencies: [dlmcommon_dep],
+    install: true,
+)
+
+dlmclient_dep = declare_dependency(
+    link_with: libdlmclient,
+    include_directories: include_directories('.')
+)
+
+
+install_headers(dlmclient_headers, subdir: 'libdlmclient')
+
+pkg.generate(
+    name: 'libdlmclient',
+    libraries: libdlmclient,
+    subdirs: [ 'libdlmclient' ],
+    version: meson.project_version(),
+    description: 'DRM lease manager client library',
+)
+
+dlmclient_header_dir = meson.current_source_dir()
+subdir('docs')
+
+if enable_tests
+  subdir('test')
+endif
diff --git a/libdlmclient/test/libdlmclient-test.c b/libdlmclient/test/libdlmclient-test.c
new file mode 100644
index 0000000..5b04c09
--- /dev/null
+++ b/libdlmclient/test/libdlmclient-test.c
@@ -0,0 +1,291 @@
+/* Copyright 2020-2021 IGEL Co., Ltd.
+ *
+ * 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 <check.h>
+
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "config.h"
+#include "dlmclient.h"
+#include "test-helpers.h"
+#include "test-socket-server.h"
+
+#define SOCKETDIR "/tmp"
+
+#define TEST_LEASE_NAME "test-lease"
+
+/**************  Test fixutre functions *************/
+struct test_config default_test_config;
+
+static void test_setup(void)
+{
+	dlm_enable_debug_log(true);
+	setenv("DLM_RUNTIME_PATH", SOCKETDIR, 1);
+
+	default_test_config = (struct test_config){
+	    .lease_name = TEST_LEASE_NAME,
+	    .nfds = 1,
+	};
+}
+
+static void test_shutdown(void)
+{
+	test_config_cleanup(&default_test_config);
+}
+
+/**************  Lease manager error tests *************/
+
+/* These tests verify that the client library gracefully handles
+ * failures when trying to receive data from the lease manager.
+ * Failures or errors in the lease manager should cause meaningful
+ * errors to be reported by the client.  Lease manager errors should
+ * not cause crashes or invalid state in the client */
+
+/* manager_connection_err
+ *
+ * Test details: Simulate socket connection failure.
+ * Expected results: dlm_get_lease() fails.
+ */
+START_TEST(manager_connection_err)
+{
+	struct server_state *sstate = test_server_start(&default_test_config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME "-bad");
+
+	ck_assert_ptr_eq(lease, NULL);
+
+	test_server_stop(sstate);
+}
+END_TEST
+
+/* no_data_from_manager
+ *
+ * Test details: Close the remote (lease manager) without sending any data.
+ *               Currently this means that the lease request has been rejected
+ *               for some reason.
+ *
+ * TODO: Update this when the client-server protocol is updated to
+ *       include the reason for the lease rejection.
+ *
+ * Expected results: dlm_get_lease() fails, errno set to EACCESS.
+ */
+START_TEST(no_data_from_manager)
+{
+
+	struct test_config config = {
+	    .lease_name = TEST_LEASE_NAME,
+	    .send_no_data = true,
+	};
+
+	struct server_state *sstate = test_server_start(&config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+
+	ck_assert_ptr_eq(lease, NULL);
+	ck_assert_int_eq(errno, EACCES);
+
+	test_server_stop(sstate);
+}
+END_TEST
+
+/* no_lease_fd_from_manager
+ *
+ * Test details: Simulate receiving response from lease manager with
+ *               no fd attached.  (i.e. a protocol error)
+ *
+ * Expected results: dlm_get_lease() fails, errno set to EPROTO.
+ */
+START_TEST(no_lease_fd_from_manager)
+{
+	/* Receive message from the lease manager with missing lease fd */
+	struct test_config config = {
+	    .lease_name = TEST_LEASE_NAME,
+	    .send_data_without_fd = true,
+	};
+
+	struct server_state *sstate = test_server_start(&config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+
+	ck_assert_ptr_eq(lease, NULL);
+	ck_assert_int_eq(errno, EPROTO);
+
+	test_server_stop(sstate);
+}
+END_TEST
+
+static void add_lease_manager_error_tests(Suite *s)
+{
+	TCase *tc = tcase_create("Lease manager error handling");
+
+	tcase_add_checked_fixture(tc, test_setup, test_shutdown);
+
+	tcase_add_test(tc, manager_connection_err);
+	tcase_add_test(tc, no_data_from_manager);
+	tcase_add_test(tc, no_lease_fd_from_manager);
+
+	suite_add_tcase(s, tc);
+}
+
+/**************  Lease handling tests  *****************/
+
+/* These tests verify that the client library handles the received
+ * lease data properly. Receiving the lease fds without leaks,
+ * properly passing the fds to the client application and cleaning
+ * them up on release.
+ */
+
+static int count_open_fds(void)
+{
+	int fds = 0;
+	DIR *dirp = opendir("/proc/self/fd");
+	while ((readdir(dirp) != NULL))
+		fds++;
+	closedir(dirp);
+	return fds;
+}
+
+/* receive_fd_from_manager
+ *
+ * Test details: Successfully receive a file descriptor.
+ * Expected results: dlm_get_lease() succeeds.
+ *                   dlm_lease_fd() returns the correct fd value.
+ */
+START_TEST(receive_fd_from_manager)
+{
+	struct server_state *sstate = test_server_start(&default_test_config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+	ck_assert_ptr_ne(lease, NULL);
+
+	int received_fd = dlm_lease_fd(lease);
+
+	int sent_fd = default_test_config.fds[0];
+
+	check_fd_equality(received_fd, sent_fd);
+
+	dlm_release_lease(lease);
+
+	test_server_stop(sstate);
+	close(sent_fd);
+}
+END_TEST
+
+/* lease_fd_is_closed_on_release
+ *
+ * Test details: Verify that dlm_release_lease() closes the lease fd.
+ * Expected results: lease fd is closed.
+ */
+START_TEST(lease_fd_is_closed_on_release)
+{
+	struct server_state *sstate = test_server_start(&default_test_config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+	ck_assert_ptr_ne(lease, NULL);
+
+	int received_fd = dlm_lease_fd(lease);
+
+	check_fd_is_open(received_fd);
+	dlm_release_lease(lease);
+	check_fd_is_closed(received_fd);
+
+	test_server_stop(sstate);
+}
+END_TEST
+
+/* dlm_lease_fd_always_returns_same_lease
+ *
+ * Test details: Verify that dlm_lease_fd() always returns the same value
+ *               for a given lease.
+ * Expected results: same value is returned when called multiple times.
+ */
+START_TEST(dlm_lease_fd_always_returns_same_lease)
+{
+	struct server_state *sstate = test_server_start(&default_test_config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+	ck_assert_ptr_ne(lease, NULL);
+
+	int received_fd = dlm_lease_fd(lease);
+
+	ck_assert_int_eq(received_fd, dlm_lease_fd(lease));
+	ck_assert_int_eq(received_fd, dlm_lease_fd(lease));
+
+	dlm_release_lease(lease);
+
+	test_server_stop(sstate);
+}
+END_TEST
+
+START_TEST(verify_that_unused_fds_are_not_leaked)
+{
+	int nopen_fds = count_open_fds();
+
+	struct test_config config = {
+	    .lease_name = TEST_LEASE_NAME,
+	    .nfds = 2,
+	};
+
+	struct server_state *sstate = test_server_start(&config);
+
+	struct dlm_lease *lease = dlm_get_lease(TEST_LEASE_NAME);
+
+	ck_assert_ptr_eq(lease, NULL);
+	ck_assert_int_eq(errno, EPROTO);
+
+	dlm_release_lease(lease);
+
+	test_server_stop(sstate);
+
+	test_config_cleanup(&config);
+	ck_assert_int_eq(nopen_fds, count_open_fds());
+}
+END_TEST
+
+static void add_lease_handling_tests(Suite *s)
+{
+	TCase *tc = tcase_create("Lease processing tests");
+
+	tcase_add_checked_fixture(tc, test_setup, test_shutdown);
+
+	tcase_add_test(tc, receive_fd_from_manager);
+	tcase_add_test(tc, lease_fd_is_closed_on_release);
+	tcase_add_test(tc, dlm_lease_fd_always_returns_same_lease);
+	tcase_add_test(tc, verify_that_unused_fds_are_not_leaked);
+	suite_add_tcase(s, tc);
+}
+
+int main(void)
+{
+	int number_failed;
+	Suite *s;
+	SRunner *sr;
+
+	s = suite_create("DLM client library tests");
+
+	add_lease_manager_error_tests(s);
+	add_lease_handling_tests(s);
+
+	sr = srunner_create(s);
+
+	srunner_run_all(sr, CK_NORMAL);
+	number_failed = srunner_ntests_failed(sr);
+	srunner_free(sr);
+	return (number_failed == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/libdlmclient/test/meson.build b/libdlmclient/test/meson.build
new file mode 100644
index 0000000..35e8575
--- /dev/null
+++ b/libdlmclient/test/meson.build
@@ -0,0 +1,6 @@
+cl_test = executable('libdlmclient-test',
+           sources: [ 'libdlmclient-test.c', 'test-socket-server.c'],
+           dependencies: [check_dep, fff_dep, dlmcommon_dep, dlmclient_dep, thread_dep],
+           include_directories: configuration_inc)
+
+test('Client library test', cl_test, is_parallel: false)
diff --git a/libdlmclient/test/test-socket-server.c b/libdlmclient/test/test-socket-server.c
new file mode 100644
index 0000000..281aaf7
--- /dev/null
+++ b/libdlmclient/test/test-socket-server.c
@@ -0,0 +1,169 @@
+/* Copyright 2020-2021 IGEL Co., Ltd.
+ *
+ * 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 "test-socket-server.h"
+#include <check.h>
+
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "socket-path.h"
+#include "test-helpers.h"
+
+static void send_fd_list_over_socket(int socket, int nfds, int *fds)
+{
+	char data;
+	struct iovec iov = {
+	    .iov_base = &data,
+	    .iov_len = 1,
+	};
+
+	int bufsize = CMSG_SPACE(nfds * sizeof(int));
+	char *buf = malloc(bufsize);
+
+	struct msghdr msg = {
+	    .msg_iov = &iov,
+	    .msg_iovlen = 1,
+	    .msg_controllen = bufsize,
+	    .msg_control = buf,
+	};
+
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+	cmsg->cmsg_len = CMSG_LEN(nfds * sizeof(int));
+	memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * nfds);
+
+	ck_assert_int_gt(sendmsg(socket, &msg, 0), 0);
+	free(buf);
+}
+
+struct server_state {
+	pthread_t tid;
+	pthread_mutex_t lock;
+	pthread_cond_t cond;
+	bool is_server_started;
+
+	struct test_config *config;
+};
+
+static void *test_server_thread(void *arg)
+{
+	struct server_state *sstate = arg;
+	struct test_config *config = sstate->config;
+
+	struct sockaddr_un address = {
+	    .sun_family = AF_UNIX,
+	};
+
+	ck_assert_int_eq(
+	    sockaddr_set_lease_server_path(&address, config->lease_name), true);
+
+	int server = socket(PF_UNIX, SOCK_STREAM, 0);
+	ck_assert_int_ge(server, 0);
+
+	unlink(address.sun_path);
+
+	int ret;
+	ret = bind(server, (struct sockaddr *)&address, sizeof(address));
+	ck_assert_int_eq(ret, 0);
+
+	ret = listen(server, 1);
+	ck_assert_int_eq(ret, 0);
+
+	sstate->is_server_started = true;
+	pthread_cond_signal(&sstate->cond);
+
+	int client = accept(server, NULL, NULL);
+	/* accept is the cancellation point for this thread. If
+	 * pthread_cancel() is called on this thread, accept() may return
+	 * -1, so don't assert on it. */
+
+	if (client < 0) {
+		close(server);
+		return NULL;
+	}
+
+	if (config->send_no_data)
+		goto done;
+
+	if (config->send_data_without_fd) {
+		char data;
+		write(client, &data, 1);
+		goto done;
+	}
+
+	if (config->nfds == 0)
+		config->nfds = 1;
+
+	config->fds = calloc(config->nfds, sizeof(int));
+
+	for (int i = 0; i < config->nfds; i++)
+		config->fds[i] = get_dummy_fd();
+
+	send_fd_list_over_socket(client, config->nfds, config->fds);
+done:
+	close(client);
+	close(server);
+	return NULL;
+}
+
+struct server_state *test_server_start(struct test_config *test_config)
+{
+	struct server_state *sstate = malloc(sizeof(*sstate));
+
+	*sstate = (struct server_state){
+	    .lock = PTHREAD_MUTEX_INITIALIZER,
+	    .cond = PTHREAD_COND_INITIALIZER,
+	    .is_server_started = false,
+	    .config = test_config,
+	};
+
+	pthread_create(&sstate->tid, NULL, test_server_thread, sstate);
+
+	pthread_mutex_lock(&sstate->lock);
+	while (!sstate->is_server_started)
+		pthread_cond_wait(&sstate->cond, &sstate->lock);
+	pthread_mutex_unlock(&sstate->lock);
+	return sstate;
+}
+
+void test_server_stop(struct server_state *sstate)
+{
+
+	ck_assert_ptr_ne(sstate, NULL);
+
+	pthread_cancel(sstate->tid);
+	pthread_join(sstate->tid, NULL);
+
+	free(sstate);
+}
+
+void test_config_cleanup(struct test_config *config)
+{
+	if (!config->fds)
+		return;
+
+	for (int i = 0; i < config->nfds; i++)
+		close(config->fds[i]);
+
+	free(config->fds);
+}
diff --git a/libdlmclient/test/test-socket-server.h b/libdlmclient/test/test-socket-server.h
new file mode 100644
index 0000000..ebdbd2d
--- /dev/null
+++ b/libdlmclient/test/test-socket-server.h
@@ -0,0 +1,33 @@
+/* Copyright 2020-2021 IGEL Co., Ltd.
+ *
+ * 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.
+ */
+
+#ifndef TEST_SOCKET_SERVER_H
+#define TEST_SOCKET_SERVER_H
+#include <stdbool.h>
+
+struct test_config {
+	char *lease_name;
+	int nfds;
+	int *fds;
+
+	bool send_data_without_fd;
+	bool send_no_data;
+};
+
+void test_config_cleanup(struct test_config *config);
+
+struct server_state *test_server_start(struct test_config *test_config);
+void test_server_stop(struct server_state *sstate);
+#endif