BobinkCOpcUa

A small C project that demonstrates OPC UA server discovery using the open62541 library. Three programs work together:

• bobink_opcua_discovery_server — Local Discovery Server that other servers register with
• bobink_opcua_server — a server that periodically registers itself with the LDS
• bobink_opcua_client — queries the LDS for servers, lists endpoints, reads the current time, or downloads a server's certificate

Prerequisites

• CMake 3.17+
• A C11 compiler (GCC or Clang)
• OpenSSL development libraries (libssl-dev / openssl-devel)
• openssl CLI (for generating certificates)

Getting started

Clone the repository with its submodule:

git clone --recursive https://git.tvcloud.fr/BobinkCOpcUa
cd BobinkCOpcUa

Certificates

Test certificates are pre-generated and committed under each test directory (e.g. tests/secure_anonymous/certs/). Each secure test has per-identity subdirectories (ServerLDS/, ServerRegister/, ServerRegisterClient/, Client/) containing cert.der and key.der, plus a shared trust/ directory with all certificates.

Programs can also run without certificates (SecurityPolicy#None only) by omitting the certificate, privateKey, and trustStore keys from their config files.

To generate new certificates, use tools/generate_certificate.sh <output_dir> <name> [uri].

Build

cmake -B build
cmake --build build --parallel

open62541 is fetched from the submodule and built automatically — the first build takes a bit longer.

Running

Start the programs in order, each in its own terminal, from the project root. Configuration files live in tests/ (one directory per test scenario — see Tests below). The examples below use tests/secure_user/:

# 1. Local Discovery Server
build/bobink_opcua_discovery_server tests/secure_user/server_lds.conf

# 2. Register Server (connects to the LDS on port 14840)
build/bobink_opcua_server tests/secure_user/server_register.conf \
  tests/secure_user/server_register_client.conf opc.tcp://localhost:14840 \
  [nodes.conf]

# 3. Find registered servers via the LDS
build/bobink_opcua_client tests/secure_user/client.conf find-servers opc.tcp://localhost:14840

# 4. List endpoints on the registered server
build/bobink_opcua_client tests/secure_user/client.conf get-endpoints opc.tcp://localhost:14841

# 5. Read the current time from the registered server
build/bobink_opcua_client tests/secure_user/client.conf read-time opc.tcp://localhost:14841

# 6. Download the server's certificate to a local file
build/bobink_opcua_client tests/secure_user/client.conf download-cert opc.tcp://localhost:14841 server.der

All three programs accept an optional log level as the last argument (trace, debug, info, warning, error, fatal). The default is info.

Tests

Integration tests exercise four combinations of security and authentication:

Run all tests:

ctest --test-dir build --output-on-failure

Memory leak check

Rebuild with AddressSanitizer, run the tests, then switch back:

# ASan build
cmake -B build \
  -DCMAKE_C_FLAGS="-fsanitize=address -fno-omit-frame-pointer" \
  -DCMAKE_EXE_LINKER_FLAGS="-fsanitize=address"
cmake --build build --parallel

ASAN_OPTIONS="detect_leaks=1" ctest --test-dir build --output-on-failure

# Restore normal build
cmake -B build -DCMAKE_C_FLAGS="" -DCMAKE_EXE_LINKER_FLAGS=""
cmake --build build --parallel

Configuration

Programs are configured through plain text files (key = value, one per line). See the tests/ directories for working examples.

Three authentication modes are supported via the authMode key:

• anonymous — no user identity
• user — username and password (requires username and password keys)
• cert — X509 certificate identity token (reuses the application certificate; requires encryption to be configured)

Nodes Configuration

bobink_opcua_server accepts an optional nodes config file that populates the server's address space with variable nodes. Pass it as the fourth positional argument (before the optional log level):

build/bobink_opcua_server server.conf client.conf opc.tcp://localhost:14840 nodes.conf

The file uses the same key = value format with dot-indexed keys:

node.0.name = Temperature
node.0.description = Current temperature reading
node.0.type = double
node.0.value = 23.5
node.0.accessLevel = read

node.1.name = DeviceName
node.1.type = string
node.1.value = Sensor-01
node.1.accessLevel = readwrite

node.2.name = Measurements
node.2.description = Recent measurements
node.2.type = double[]
node.2.value = 1.5, 2.3, 3.7, 4.1
node.2.accessLevel = read

Each node gets a string NodeId in namespace 1 (ns=1;s=<name>). The name field is also used as the display name and browse name.

Fields

Supported Types

Append [] to any type name for a 1D array (e.g. double[], string[]). Array values are comma-separated. String values in arrays cannot contain literal commas.