# BobinkCOpcUa

A small C project that demonstrates OPC UA server discovery using the
[open62541](https://www.open62541.org/) 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:

```sh
git clone --recursive https://git.tvcloud.fr/opcua_c
cd opcua_c
```

### 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

```sh
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](#tests) below). The examples below use `tests/secure_user/`:

```sh
# 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

# 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:

| Test | Security | Auth |
|------|----------|------|
| `unsecure_anonymous` | None / None | anonymous |
| `secure_anonymous` | SignAndEncrypt / Aes256_Sha256_RsaPss | anonymous |
| `secure_user` | SignAndEncrypt / Aes256_Sha256_RsaPss | user/password |
| `secure_cert` | SignAndEncrypt / Aes256_Sha256_RsaPss | X509 certificate |
| `download_cert` | SignAndEncrypt / Aes256_Sha256_RsaPss | anonymous (download-cert) |

Run all tests:

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

### Memory leak check

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

```sh
# 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)