Srun

Yet another Srun login utility, but written in C and with ESP32 support.

The main files srun.h and srun.c can be dropped into an existing project and compile along with it. You may also build an executable directly for your OS.

Build for *nix

Dependencies:

• libbsd
• OpenSSL 3
• LibcURL
• cJSON

sudo apt install cmake openssl libssl-dev libbsd-dev libcurl4-openssl-dev libcjson-dev
cmake -B cmake-build -DCMAKE_BUILD_TYPE=RelWithDebInfo  # or Release, at your choice
cmake --build cmake-build --config RelWithDebInfo

Build for ESP32

Warning

While this library currently works on ESP32, it's not yet fully tested. Currently there are some known memory leaks, and should be used with caution, until this warning is removed.

The ESP32 version uses Mbed TLS library comes along with ESP-IDF. The source should be able to detect this automatically.

Example Usage

Login

srun_handle handle = srun_create();
srun_setopt(handle, SRUNOPT_AUTH_SERVER, "auth server URL");
srun_setopt(handle, SRUNOPT_USERNAME, "username");
srun_setopt(handle, SRUNOPT_PASSWORD, "password");
srun_setopt(handle, SRUNOPT_SERVER_CERT, "auth server certificate (PEM format)"); // explained below
srun_setopt(handle, SRUNOPT_USE_ESP_CRT_BUNDLE, 1); // set to 1 to use ESP x509 certificate bundle
printf("login result: %d\n", srun_login(handle));
srun_cleanup(handle);
handle = NULL;

The server CA certificate needs to be set if your auth server uses HTTPS, and if either:

• you are running on ESP32, and not using / certificate is not trusted by ESP x509 certificate bundle
• your auth server uses a self-signed certificate (that is not trusted by your system's global CA store)

For security concerns there is no option to skip certificate verification. Evaluate the risk before modifying the code yourself please.

All fields except server certificate is copied into the context. The password field is used as HMAC-MD5 key and the internal buffer is filled with zero before being freed by srun_cleanup().

Logout

srun_handle handle = srun_create();
srun_setopt(handle, SRUNOPT_AUTH_SERVER, "auth server URL");
srun_setopt(handle, SRUNOPT_SERVER_CERT, "auth server certificate (PEM format)");
printf("logout result: %d\n", srun_logout(handle));
srun_cleanup(handle);
handle = NULL;

Username and password are not needed when logging out. The same context used for login may be reused.