under `MIT` or the [UNLICENSE](http://unlicense.org/).

## Features

Implements [OpenID Connect Core 1.0](https://openid.net/specs/openid-connect-core-1_0.html) and [OpenID Connect Discovery 1.0](https://openid.net/specs/openid-connect-discovery-1_0.html).

Implements [UMA2](https://docs.kantarainitiative.org/uma/wg/oauth-uma-federated-authz-2.0-09.html) - User Managed Access, an extension to OIDC/OAuth2. Use feature flag `uma2` to enable this feature.

Implements [OAuth 2.0 Token Introspection](https://datatracker.ietf.org/doc/html/rfc7662).

Implements [PKCE: Proof Key for Code Exchange by OAuth Public Clients](https://datatracker.ietf.org/doc/html/rfc7636). PKCE is enabled by default. Please note that PKCE is not rotating keys, but rather using a single key pair for the entire lifetime of the application. One can rotate the key pair by calling the `refresh_pkce` method on client. Ideally, this should be done after each generation of authorization url.

It supports Microsoft OIDC with feature `microsoft`. This adds methods for authentication and token validation, those skip issuer check.

Originally developed as a quick adaptation to leverage async/await functionality, based on [inth-oauth2](https://crates.io/crates/inth-oauth2) and [oidc](https://crates.io/crates/oidc), the library has since evolved into a mature and robust solution, offering expanded features and improved performance.

Using [reqwest](https://crates.io/crates/reqwest) for the HTTP client and [biscuit](https://crates.io/crates/biscuit) for Javascript Object Signing and Encryption (JOSE).

## Support:

You can contribute to the ongoing development and maintenance of OpenID library in various ways:

### Sponsorship

Your support, no matter how big or small, helps sustain the project and ensures its continued improvement. Reach out to explore sponsorship opportunities.

### Feedback

Whether you are a developer, user, or enthusiast, your feedback is invaluable. Share your thoughts, suggestions, and ideas to help shape the future of the library.

### Contribution

If you're passionate about open-source and have skills to share, consider contributing to the project. Every contribution counts!

Thank you for being part of OpenID community. Together, we are making authentication processes more accessible, reliable, and efficient for everyone.

## Usage

Add dependency to Cargo.toml:

```toml
[dependencies]
openid = "0.23"
```

By default we use native tls, if you want to use `rustls`:

```toml
[dependencies]
openid = { version = "0.23", default-features = false, features = ["rustls"] }
```

### Use case: [Warp](https://crates.io/crates/warp) web server with [JHipster](https://www.jhipster.tech/) generated frontend and [Google OpenID Connect](https://developers.google.com/identity/protocols/OpenIDConnect)

This example provides only Rust part, assuming just default JHipster frontend settings.

in Cargo.toml:

```toml
[dependencies]
anyhow = "1.0"
cookie = "0.18"
dotenv = "0.15"
log = "0.4"
openid = "0.23"
pretty_env_logger = "0.5"
reqwest = "0.13"
serde = { version = "1", default-features = false, features = [ "derive" ] }
serde_json = "1"
tokio = { version = "1", default-features = false, features = [ "rt-multi-thread", "macros" ] }
uuid = { version = "1", default-features = false, features = [ "v4" ] }
warp = { version = "0.4", default-features = false, features = [ "server" ] }
```

in src/main.rs:

```rust, compile_fail
use std::{convert::Infallible, env, net::SocketAddr, sync::Arc};

use cookie::time::Duration;
use log::{error, info};
use tokio::sync::RwLock;
use warp::{
    Filter, Rejection, Reply,
    http::{Response, StatusCode},
    reject,
};

use openid::{Client, Discovered, DiscoveredClient, Options, StandardClaims, Token, Userinfo};
use openid_examples::{
    INDEX_HTML,
    entity::{LoginQuery, Sessions, User},
};

type OpenIDClient = Client<Discovered, StandardClaims>;

const EXAMPLE_COOKIE: &str = "openid_warp_example";

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    dotenv::dotenv().ok();

    pretty_env_logger::init();

    let client_id = env::var("CLIENT_ID").expect("<client id> for your provider");
    let client_secret = env::var("CLIENT_SECRET").ok();
    let issuer_url =
        env::var("ISSUER").unwrap_or_else(|_| "https://accounts.google.com".to_string());
    let redirect = Some(host("/login/oauth2/code/oidc"));
    let issuer = reqwest::Url::parse(&issuer_url)?;
    let listen: SocketAddr = env::var("LISTEN")
        .unwrap_or_else(|_| "127.0.0.1:8080".to_string())
        .parse()?;

    info!("redirect: {redirect:?}");
    info!("issuer: {issuer}");

    let client = Arc::new(
        DiscoveredClient::discover(
            client_id,
            client_secret.unwrap_or_default(),
            redirect,
            issuer,
        )
        .await?,
    );

    info!("discovered config: {:?}", client.config());

    let with_client = |client: Arc<Client<_>>| warp::any().map(move || client.clone());

    let sessions = Arc::new(RwLock::new(Sessions::default()));

    let with_sessions = |sessions: Arc<RwLock<Sessions>>| warp::any().map(move || sessions.clone());

    let index = warp::path::end()
        .and(warp::get())
        .map(|| warp::reply::html(INDEX_HTML));

    let authorize = warp::path!("oauth2" / "authorization" / "oidc")
        .and(warp::get())
        .and(with_client(client.clone()))
        .and_then(reply_authorize);

    let login = warp::path!("login" / "oauth2" / "code" / "oidc")
        .and(warp::get())
        .and(with_client(client.clone()))
        .and(warp::query::<LoginQuery>())
        .and(with_sessions(sessions.clone()))
        .and_then(reply_login);

    let logout = warp::path!("logout")
        .and(warp::get())
        .and(with_client(client.clone()))
        .and(warp::cookie::optional(EXAMPLE_COOKIE))
        .and(with_sessions(sessions.clone()))
        .and_then(reply_logout);

    let api_account = warp::path!("api" / "account")
        .and(warp::get())
        .and(with_user(sessions))
        .map(|user: User| warp::reply::json(&user));

    let routes = index
        .or(authorize)
        .or(login)
        .or(logout)
        .or(api_account)
        .recover(handle_rejections);

    let logged_routes = routes.with(warp::log("openid_warp_example"));

    warp::serve(logged_routes).run(listen).await;

    Ok(())
}

async fn request_token(
    oidc_client: &OpenIDClient,
    login_query: &LoginQuery,
) -> anyhow::Result<Option<(Token, Userinfo)>> {
    let mut token: Token = oidc_client.request_token(&login_query.code).await?.into();

    if let Some(id_token) = token.id_token.as_mut() {
        oidc_client.decode_token(id_token)?;
        oidc_client.validate_token(id_token, None, None)?;
        info!("token: {id_token:?}");
    } else {
        return Ok(None);
    }

    let userinfo = oidc_client.request_userinfo(&token).await?;

    info!("user info: {userinfo:?}");

    Ok(Some((token, userinfo)))
}

async fn reply_login(
    oidc_client: Arc<OpenIDClient>,
    login_query: LoginQuery,
    sessions: Arc<RwLock<Sessions>>,
) -> Result<impl warp::Reply, Infallible> {
    let request_token = request_token(&oidc_client, &login_query).await;
    match request_token {
        Ok(Some((token, user_info))) => {
            let id = uuid::Uuid::new_v4().to_string();

            let login = user_info.preferred_username.clone();
            let email = user_info.email.clone();

            let user = User {
                id: user_info.sub.clone(),
                login,
                last_name: user_info.family_name.clone(),
                first_name: user_info.name.clone(),
                email,
                activated: user_info.email_verified,
                image_url: user_info.picture.clone().map(|x| x.to_string()),
                lang_key: Some("en".to_string()),
                authorities: vec!["ROLE_USER".to_string()],
            };

            let authorization_cookie = ::cookie::Cookie::build((EXAMPLE_COOKIE, &id))
                .path("/")
                .http_only(true)
                .build()
                .to_string();

            sessions
                .write()
                .await
                .map
                .insert(id, (user, token, user_info));

            let redirect_url = login_query.state.clone().unwrap_or_else(|| host("/"));

            Ok(Response::builder()
                .status(StatusCode::MOVED_PERMANENTLY)
                .header(warp::http::header::LOCATION, redirect_url)
                .header(warp::http::header::SET_COOKIE, authorization_cookie)
                .body("")
                .unwrap())
        }
        Ok(None) => {
            error!("login error in call: no id_token found");

            response_unauthorized()
        }
        Err(err) => {
            error!("login error in call: {err:?}");

            response_unauthorized()
        }
    }
}

fn response_unauthorized() -> Result<Response<&'static str>, Infallible> {
    Ok(Response::builder()
        .status(StatusCode::UNAUTHORIZED)
        .body("")
        .unwrap())
}

async fn reply_logout(
    oidc_client: Arc<OpenIDClient>,
    session_id: Option<String>,
    sessions: Arc<RwLock<Sessions>>,
) -> Result<impl warp::Reply, Infallible> {
    let Some(id) = session_id else {
        return response_unauthorized();
    };

    let session_removed = sessions.write().await.map.remove(&id);

    if let Some(id_token) = session_removed.and_then(|(_, token, _)| token.bearer.id_token) {
        let authorization_cookie = ::cookie::Cookie::build((EXAMPLE_COOKIE, &id))
            .path("/")
            .http_only(true)
            .max_age(Duration::seconds(-1))
            .build()
            .to_string();

        let return_redirect_url = host("/");

        let redirect_url = oidc_client
            .config()
            .end_session_endpoint
            .clone()
            .map(|mut logout_provider_endpoint| {
                logout_provider_endpoint
                    .query_pairs_mut()
                    .append_pair("id_token_hint", &id_token)
                    .append_pair("post_logout_redirect_uri", &return_redirect_url);
                logout_provider_endpoint.to_string()
            })
            .unwrap_or_else(|| return_redirect_url);

        info!("logout redirect url: {redirect_url}");

        Ok(Response::builder()
            .status(StatusCode::FOUND)
            .header(warp::http::header::LOCATION, redirect_url)
            .header(warp::http::header::SET_COOKIE, authorization_cookie)
            .body("")
            .unwrap())
    } else {
        response_unauthorized()
    }
}

async fn reply_authorize(oidc_client: Arc<OpenIDClient>) -> Result<impl warp::Reply, Infallible> {
    let origin_url = env::var("ORIGIN").unwrap_or_else(|_| host(""));

    let auth_url = oidc_client.auth_url(&Options {
        scope: Some("openid email profile".into()),
        state: Some(origin_url),
        ..Default::default()
    });

    info!("authorize: {auth_url}");

    let url: String = auth_url.into();

    Ok(warp::reply::with_header(
        StatusCode::FOUND,
        warp::http::header::LOCATION,
        url,
    ))
}

#[derive(Debug)]
struct Unauthorized;

impl reject::Reject for Unauthorized {}

async fn extract_user(
    session_id: Option<String>,
    sessions: Arc<RwLock<Sessions>>,
) -> Result<User, Rejection> {
    if let Some(session_id) = session_id {
        if let Some((user, _, _)) = sessions.read().await.map.get(&session_id) {
            Ok(user.clone())
        } else {
            Err(warp::reject::custom(Unauthorized))
        }
    } else {
        Err(warp::reject::custom(Unauthorized))
    }
}

fn with_user(
    sessions: Arc<RwLock<Sessions>>,
) -> impl Filter<Extract = (User,), Error = Rejection> + Clone {
    warp::cookie::optional(EXAMPLE_COOKIE)
        .and(warp::any().map(move || sessions.clone()))
        .and_then(extract_user)
}

async fn handle_rejections(err: Rejection) -> Result<impl Reply, Infallible> {
    let code = if err.is_not_found() {
        StatusCode::NOT_FOUND
    } else if let Some(Unauthorized) = err.find() {
        StatusCode::UNAUTHORIZED
    } else {
        StatusCode::INTERNAL_SERVER_ERROR
    };

    Ok(warp::reply::with_status(warp::reply(), code))
}

/// This host is the address, where user would be redirected after initial authorization.
/// For DEV environment with WebPack this is usually something like `http://localhost:9000`.
/// We are using `http://localhost:8080` in all-in-one example.
pub fn host(path: &str) -> String {
    env::var("REDIRECT_URL").unwrap_or_else(|_| "http://localhost:8080".to_string()) + path
}
```

See full example: [openid-examples: warp](https://github.com/kilork/openid-examples/blob/v0.23/examples/warp.rs)
