Add lease request and release protocol

Explicitly request / release leases instead of implicitly
by opening and closing the connection.  This will allow the
lease manager to take different action when a client
shuts down gracefully vs when it crashes, holding a lease.

Bug-AGL: SPEC-3862

Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Change-Id: Ibc68bee855ce18e56eb6f57e5ad1743248320013

3 files changed, 99 insertions, 0 deletions

diff --git a/common/dlm-protocol.c b/common/dlm-protocol.c
new file mode 100644
index 0000000..4fc87b2
--- /dev/null
+++ b/common/dlm-protocol.c
@@ -0,0 +1,66 @@
+/* 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 "dlm-protocol.h"
+
+#include <errno.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+bool receive_dlm_client_request(int socket, struct dlm_client_request *request)
+{
+
+	ssize_t len;
+	struct iovec iov = {
+	    .iov_base = request,
+	    .iov_len = sizeof(*request),
+	};
+	struct msghdr msg = {
+	    .msg_iov = &iov,
+	    .msg_iovlen = 1,
+	};
+
+	while ((len = recvmsg(socket, &msg, 0)) < 0) {
+		if (errno != EINTR)
+			return false;
+	}
+
+	if (len != sizeof(*request)) {
+		errno = EPROTO;
+		return false;
+	}
+	return true;
+}
+
+bool send_dlm_client_request(int socket, struct dlm_client_request *request)
+{
+	struct iovec iov = {
+	    .iov_base = request,
+	    .iov_len = sizeof(*request),
+	};
+
+	struct msghdr msg = {
+	    .msg_iov = &iov,
+	    .msg_iovlen = 1,
+	};
+
+	while (sendmsg(socket, &msg, 0) < 1) {
+		if (errno != EINTR)
+			return false;
+	}
+	return true;
+}
diff --git a/common/dlm-protocol.h b/common/dlm-protocol.h
new file mode 100644
index 0000000..44785e5
--- /dev/null
+++ b/common/dlm-protocol.h
@@ -0,0 +1,32 @@
+/* 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 DLM_PROTOCOL_H
+#define DLM_PROTOCOL_H
+
+#include <stdbool.h>
+
+enum dlm_opcode {
+	DLM_GET_LEASE,
+	DLM_RELEASE_LEASE,
+};
+
+struct dlm_client_request {
+	enum dlm_opcode opcode;
+};
+
+bool receive_dlm_client_request(int socket, struct dlm_client_request *request);
+bool send_dlm_client_request(int socket, struct dlm_client_request *request);
+#endif
diff --git a/common/meson.build b/common/meson.build
index e465fa5..663c1ce 100644
--- a/common/meson.build
+++ b/common/meson.build
@@ -1,4 +1,5 @@
 libdlmcommon_sources = [
+        'dlm-protocol.c',
         'socket-path.c',
         'log.c'
 ]