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.

1 files changed, 281 insertions, 0 deletions

diff --git a/src/client_find_servers.c b/src/client_find_servers.c
new file mode 100644
index 0000000..c62fc15
--- /dev/null
+++ b/src/client_find_servers.c
@@ -0,0 +1,281 @@
+/**
+ * @file  client_find_servers.c
+ * @brief OPC UA client that queries a Local Discovery Server for registered
+ * servers.
+ *
+ * This program connects to an LDS and calls the FindServers service to
+ * retrieve all registered servers. It then queries each server's endpoints
+ * using the GetEndpoints service and displays the results in a human-readable
+ * format.
+ */
+
+#include "common.h"
+
+#include <open62541/client_highlevel.h>
+#include <open62541/plugin/log_stdout.h>
+
+#include <stdlib.h>
+#include <string.h>
+
+/* ========================================================================
+ * Discovery Service Calls
+ * ======================================================================== */
+
+/**
+ * Calls the FindServers service on the LDS and prints all discovered servers.
+ *
+ * @param client The OPC UA client instance.
+ * @param discoveryServerEndpoint The LDS endpoint URL.
+ * @param applicationDescriptionArraySize Output: number of servers found.
+ * @param applicationDescriptionArray Output: array of server descriptions.
+ * @return UA_STATUSCODE_GOOD on success, error code otherwise.
+ */
+static UA_StatusCode
+findServers (UA_Client *client, const char *discoveryServerEndpoint,
+             size_t *applicationDescriptionArraySize,
+             UA_ApplicationDescription **applicationDescriptionArray)
+{
+  UA_StatusCode retval = UA_Client_findServers (
+      client, discoveryServerEndpoint, 0, NULL, 0, NULL,
+      applicationDescriptionArraySize, applicationDescriptionArray);
+
+  if (retval != UA_STATUSCODE_GOOD)
+    {
+      UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
+                    "Could not call FindServers service. "
+                    "Is the discovery server started? StatusCode %s",
+                    UA_StatusCode_name (retval));
+      return retval;
+    }
+
+  for (size_t i = 0; i < *applicationDescriptionArraySize; i++)
+    printApplicationDescription (&(*applicationDescriptionArray)[i], i);
+
+  return UA_STATUSCODE_GOOD;
+}
+
+/**
+ * Queries endpoints for each discovered server using the GetEndpoints service.
+ *
+ * For each server in the applicationDescriptionArray, this function extracts
+ * the first discovery URL and calls GetEndpoints to retrieve all available
+ * endpoints. Results are logged via UA_LOG_INFO.
+ *
+ * @param client The OPC UA client instance.
+ * @param applicationDescriptionArray Array of server descriptions from
+ * FindServers.
+ * @param applicationDescriptionArraySize Number of servers in the array.
+ */
+static void
+getServersEndpoints (UA_Client *client,
+                     UA_ApplicationDescription *applicationDescriptionArray,
+                     size_t applicationDescriptionArraySize)
+{
+  for (size_t i = 0; i < applicationDescriptionArraySize; i++)
+    {
+      UA_ApplicationDescription *description = &applicationDescriptionArray[i];
+      if (description->discoveryUrlsSize == 0)
+        {
+          UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
+                       "[GetEndpoints] Server %.*s did not provide any "
+                       "discovery urls. Skipping.",
+                       (int)description->applicationUri.length,
+                       description->applicationUri.data);
+          continue;
+        }
+
+      /* UA_String is not null-terminated; build a C string for the API. */
+      char *discoveryUrl = (char *)UA_malloc (
+          sizeof (char) * description->discoveryUrls[0].length + 1);
+      memcpy (discoveryUrl, description->discoveryUrls[0].data,
+              description->discoveryUrls[0].length);
+      discoveryUrl[description->discoveryUrls[0].length] = '\0';
+
+      UA_EndpointDescription *endpointArray = NULL;
+      size_t endpointArraySize = 0;
+      UA_StatusCode retval = UA_Client_getEndpoints (
+          client, discoveryUrl, &endpointArraySize, &endpointArray);
+      UA_free (discoveryUrl);
+      if (retval != UA_STATUSCODE_GOOD)
+        {
+          UA_Client_disconnect (client);
+          break;
+        }
+
+      UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_APPLICATION,
+                   "Endpoints for Server[%lu]: %.*s", (unsigned long)i,
+                   (int)description->applicationUri.length,
+                   description->applicationUri.data);
+      for (size_t j = 0; j < endpointArraySize; j++)
+        printEndpoint (&endpointArray[j], j);
+
+      UA_Array_delete (endpointArray, endpointArraySize,
+                       &UA_TYPES[UA_TYPES_ENDPOINTDESCRIPTION]);
+    }
+}
+
+/* ========================================================================
+ * Node Reading
+ * ======================================================================== */
+
+/**
+ * Connects to each non-discovery server and reads the current time node.
+ *
+ * For each server that is not a DiscoveryServer, this function establishes a
+ * secure session, reads the Server_ServerStatus_CurrentTime variable, prints
+ * the result, and disconnects.
+ *
+ * @param client The OPC UA client instance.
+ * @param applicationDescriptionArray Array of server descriptions from
+ * FindServers.
+ * @param applicationDescriptionArraySize Number of servers in the array.
+ */
+static void
+readServerTime (UA_Client *client,
+                UA_ApplicationDescription *applicationDescriptionArray,
+                size_t applicationDescriptionArraySize)
+{
+  for (size_t i = 0; i < applicationDescriptionArraySize; i++)
+    {
+      UA_ApplicationDescription *desc = &applicationDescriptionArray[i];
+
+      if (desc->applicationType == UA_APPLICATIONTYPE_DISCOVERYSERVER)
+        continue;
+
+      if (desc->discoveryUrlsSize == 0)
+        {
+          UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
+                       "[ReadTime] Server %.*s has no discovery URLs. "
+                       "Skipping.",
+                       (int)desc->applicationUri.length,
+                       desc->applicationUri.data);
+          continue;
+        }
+
+      /* UA_String is not null-terminated; build a C string for the API. */
+      char *url = (char *)UA_malloc (desc->discoveryUrls[0].length + 1);
+      memcpy (url, desc->discoveryUrls[0].data, desc->discoveryUrls[0].length);
+      url[desc->discoveryUrls[0].length] = '\0';
+
+      UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
+                   "Connecting to %s to read current time...", url);
+
+      UA_StatusCode retval = UA_Client_connect (client, url);
+      UA_free (url);
+      if (retval != UA_STATUSCODE_GOOD)
+        {
+          UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
+                        "Could not connect: %s", UA_StatusCode_name (retval));
+          continue;
+        }
+
+      UA_Variant value;
+      UA_Variant_init (&value);
+
+      const UA_NodeId nodeId = UA_NS0ID (SERVER_SERVERSTATUS_CURRENTTIME);
+      retval = UA_Client_readValueAttribute (client, nodeId, &value);
+
+      if (retval == UA_STATUSCODE_GOOD
+          && UA_Variant_hasScalarType (&value, &UA_TYPES[UA_TYPES_DATETIME]))
+        {
+          UA_DateTime raw_date = *(UA_DateTime *)value.data;
+          UA_DateTimeStruct dts = UA_DateTime_toStruct (raw_date);
+          UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_APPLICATION,
+                       "date is: %u-%u-%u %u:%u:%u.%03u", dts.day, dts.month,
+                       dts.year, dts.hour, dts.min, dts.sec, dts.milliSec);
+        }
+      else
+        {
+          UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
+                        "Could not read current time: %s",
+                        UA_StatusCode_name (retval));
+        }
+
+      UA_Variant_clear (&value);
+      UA_Client_disconnect (client);
+    }
+}
+
+/* ========================================================================
+ * Main
+ * ======================================================================== */
+
+int
+main (int argc, char **argv)
+{
+  if (argc < 7)
+    {
+      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
+                    "Usage: %s <discovery-server-endpoint>\n"
+                    "  <applicationUri>\n"
+                    "  <certificate.der> <private-key.der>\n"
+                    "  <security-mode> <security-policy>\n"
+                    "  [<trustlist1.der>, ...]\n"
+                    "\n"
+                    "Security modes : None, Sign, SignAndEncrypt\n"
+                    "Security policies: None, Basic256Sha256, "
+                    "Aes256_Sha256_RsaPss,\n"
+                    "                   Aes128_Sha256_RsaOaep, ECC_nistP256",
+                    argv[0]);
+      return EXIT_FAILURE;
+    }
+
+  const char *discoveryServerEndpoint = argv[1];
+  const char *applicationUri = argv[2];
+  const char *certPath = argv[3];
+  const char *keyPath = argv[4];
+
+  UA_MessageSecurityMode securityMode = parseSecurityMode (argv[5]);
+  if (securityMode == UA_MESSAGESECURITYMODE_INVALID)
+    {
+      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
+                    "Unknown security mode: %s", argv[5]);
+      return EXIT_FAILURE;
+    }
+
+  const char *securityPolicyUri = resolveSecurityPolicyUri (argv[6]);
+  if (!securityPolicyUri)
+    {
+      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
+                    "Unknown security policy: %s", argv[6]);
+      return EXIT_FAILURE;
+    }
+
+  char **trustPaths = argv + 7;
+  size_t trustSize = (argc > 7) ? (size_t)argc - 7 : 0;
+
+  UA_Client *client = UA_Client_new ();
+  UA_StatusCode retval = createSecureClientConfig (
+      UA_Client_getConfig (client), applicationUri, certPath, keyPath,
+      trustPaths, trustSize, securityMode, securityPolicyUri);
+  if (retval != UA_STATUSCODE_GOOD)
+    {
+      UA_Client_delete (client);
+      return EXIT_FAILURE;
+    }
+
+  UA_ApplicationDescription *applicationDescriptionArray = NULL;
+  size_t applicationDescriptionArraySize = 0;
+
+  retval = findServers (client, discoveryServerEndpoint,
+                        &applicationDescriptionArraySize,
+                        &applicationDescriptionArray);
+  if (retval != UA_STATUSCODE_GOOD)
+    {
+      UA_Client_delete (client);
+      return EXIT_FAILURE;
+    }
+
+  getServersEndpoints (client, applicationDescriptionArray,
+                       applicationDescriptionArraySize);
+
+  readServerTime (client, applicationDescriptionArray,
+                  applicationDescriptionArraySize);
+
+  UA_Client_delete (client);
+  UA_Array_delete (applicationDescriptionArray,
+                   applicationDescriptionArraySize,
+                   &UA_TYPES[UA_TYPES_APPLICATIONDESCRIPTION]);
+
+  return EXIT_SUCCESS;
+}