From c35eb35bb63a97b7c46e879819757a9cb48165b5 Mon Sep 17 00:00:00 2001
From: Thomas Vanbesien <tvanbesi@proton.me>
Date: Tue, 17 Feb 2026 02:27:51 +0100
Subject: Initial commit: OPC UA discovery project

CMake-based C project using open62541 for OPC UA discovery.
Includes Local Discovery Server, register server, and find
servers client with OpenSSL encryption support.
---
 src/server_lds.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/server_lds.c

(limited to 'src/server_lds.c')

diff --git a/src/server_lds.c b/src/server_lds.c
new file mode 100644
index 0000000..a7794aa
--- /dev/null
+++ b/src/server_lds.c
@@ -0,0 +1,81 @@
+/**
+ * @file  server_lds.c
+ * @brief Local Discovery Server implementation.
+ *
+ * This program runs an OPC UA Local Discovery Server (LDS) configured with
+ * encryption and a configurable cleanup timeout. Other OPC UA servers register
+ * with this LDS using the RegisterServer2 service. Clients can query this LDS
+ * using the FindServers service to discover registered servers.
+ */
+
+#include "common.h"
+
+#include <open62541/plugin/log_stdout.h>
+#include <open62541/server.h>
+#include <open62541/server_config_default.h>
+
+#include <signal.h>
+#include <stdlib.h>
+
+UA_Boolean running = true;
+
+static void
+stopHandler (int sig)
+{
+  UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
+  running = false;
+}
+
+int
+main (int argc, char *argv[])
+{
+  signal (SIGINT, stopHandler);
+  signal (SIGTERM, stopHandler);
+
+  if (argc < 6)
+    {
+      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
+                    "Usage: %s\n"
+                    "  <port> <applicationUri>\n"
+                    "  <server-certificate.der> <private-key.der>\n"
+                    "  <cleanup-timeout-seconds>\n"
+                    "  [<trustlist1.der>, ...]",
+                    argv[0]);
+      return EXIT_FAILURE;
+    }
+
+  UA_UInt16 port = (UA_UInt16)atoi (argv[1]);
+  int cleanupTimeout = atoi (argv[5]);
+
+  /* The OPC UA specification requires the cleanup timeout to exceed the
+     register-server interval.  open62541 enforces a floor of 10 seconds. */
+  if (cleanupTimeout <= 10)
+    {
+      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
+                    "Cleanup timeout must be > 10 seconds (got %d)",
+                    cleanupTimeout);
+      return EXIT_FAILURE;
+    }
+  size_t trustSize = (argc > 6) ? (size_t)argc - 6 : 0;
+
+  UA_StatusCode retval;
+  UA_Server *server = createSecureServer (port, argv[2], argv[3], argv[4],
+                                          argv + 6, trustSize, &retval);
+  if (!server)
+    return EXIT_FAILURE;
+
+  UA_ServerConfig *serverConfig = UA_Server_getConfig (server);
+
+  /* Mark this server as a Discovery Server so clients can identify it. */
+  serverConfig->applicationDescription.applicationType
+      = UA_APPLICATIONTYPE_DISCOVERYSERVER;
+
+  /* Time (seconds) after which stale registrations are removed.  Must
+     exceed the registering server's re-register interval. */
+  serverConfig->discoveryCleanupTimeout = cleanupTimeout;
+
+  retval = UA_Server_run (server, &running);
+
+  UA_Server_delete (server);
+  return retval == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
+}
-- 
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