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    //! Session management for Actix Web.
    //!
    //! The HTTP protocol, at a first glance, is stateless: the client sends a request, the server
    //! parses its content, performs some processing and returns a response. The outcome is only
    //! influenced by the provided inputs (i.e. the request content) and whatever state the server
    //! queries while performing its processing.
    //!
    //! Stateless systems are easier to reason about, but they are not quite as powerful as we need them
    //! to be - e.g. how do you authenticate a user? The user would be forced to authenticate **for
    //! every single request**. That is, for example, how 'Basic' Authentication works. While it may
    //! work for a machine user (i.e. an API client), it is impractical for a person—you do not want a
    //! login prompt on every single page you navigate to!
    //!
    //! There is a solution - **sessions**. Using sessions the server can attach state to a set of
    //! requests coming from the same client. They are built on top of cookies - the server sets a
    //! cookie in the HTTP response (`Set-Cookie` header), the client (e.g. the browser) will store the
    //! cookie and play it back to the server when sending new requests (using the `Cookie` header).
    //!
    //! We refer to the cookie used for sessions as a **session cookie**. Its content is called
    //! **session key** (or **session ID**), while the state attached to the session is referred to as
    //! **session state**.
    //!
    //! `actix-session` provides an easy-to-use framework to manage sessions in applications built on
    //! top of Actix Web. [`SessionMiddleware`] is the middleware underpinning the functionality
    //! provided by `actix-session`; it takes care of all the session cookie handling and instructs the
    //! **storage backend** to create/delete/update the session state based on the operations performed
    //! against the active [`Session`].
    //!
    //! `actix-session` provides some built-in storage backends: ([`CookieSessionStore`],
    //! [`RedisSessionStore`], and [`RedisActorSessionStore`]) - you can create a custom storage backend
    //! by implementing the [`SessionStore`] trait.
    //!
    //! Further reading on sessions:
    //! - [RFC6265](https://datatracker.ietf.org/doc/html/rfc6265);
    //! - [OWASP's session management cheat-sheet](https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html).
    //!
    //! # Getting started
    //! To start using sessions in your Actix Web application you must register [`SessionMiddleware`]
    //! as a middleware on your `App`:
    //!
    //! ```no_run
    //! use actix_web::{web, App, HttpServer, HttpResponse, Error};
    //! use actix_session::{Session, SessionMiddleware, storage::RedisActorSessionStore};
    //! use actix_web::cookie::Key;
    //!
    //! #[actix_web::main]
    //! async fn main() -> std::io::Result<()> {
    //!     // The secret key would usually be read from a configuration file/environment variables.
    //!     let secret_key = Key::generate();
    //!     let redis_connection_string = "127.0.0.1:6379";
    //!     HttpServer::new(move ||
    //!             App::new()
    //!             // Add session management to your application using Redis for session state storage
    //!             .wrap(
    //!                 SessionMiddleware::new(
    //!                     RedisActorSessionStore::new(redis_connection_string),
    //!                     secret_key.clone()
    //!                 )
    //!             )
    //!             .default_service(web::to(|| HttpResponse::Ok())))
    //!         .bind(("127.0.0.1", 8080))?
    //!         .run()
    //!         .await
    //! }
    //! ```
    //!
    //! The session state can be accessed and modified by your request handlers using the [`Session`]
    //! extractor.
    //!
    //! ```no_run
    //! use actix_web::Error;
    //! use actix_session::Session;
    //!
    //! fn index(session: Session) -> Result<&'static str, Error> {
    //!     // access the session state
    //!     if let Some(count) = session.get::<i32>("counter")? {
    //!         println!("SESSION value: {}", count);
    //!         // modify the session state
    //!         session.insert("counter", count + 1)?;
    //!     } else {
    //!         session.insert("counter", 1)?;
    //!     }
    //!
    //!     Ok("Welcome!")
    //! }
    //! ```
    //!
    //! # Choosing A Backend
    //!
    //! By default, `actix-session` does not provide any storage backend to retrieve and save the state
    //! attached to your sessions. You can enable:
    //!
    //! - a purely cookie-based "backend", [`CookieSessionStore`], using the `cookie-session` feature
    //!   flag.
    //!
    //!   ```toml
    //!   [dependencies]
    //!   # ...
    //!   actix-session = { version = "...", features = ["cookie-session"] }
    //!   ```
    //!
    //! - a Redis-based backend via [`actix-redis`](https://docs.rs/acitx-redis),
    //!   [`RedisActorSessionStore`], using the `redis-actor-session` feature flag.
    //!
    //!   ```toml
    //!   [dependencies]
    //!   # ...
    //!   actix-session = { version = "...", features = ["redis-actor-session"] }
    //!   ```
    //!
    //! - a Redis-based backend via [`redis-rs`](https://docs.rs/redis-rs), [`RedisSessionStore`], using
    //!   the `redis-rs-session` feature flag.
    //!
    //!   ```toml
    //!   [dependencies]
    //!   # ...
    //!   actix-session = { version = "...", features = ["redis-rs-session"] }
    //!   ```
    //!
    //!   Add the `redis-rs-tls-session` feature flag if you want to connect to Redis using a secured
    //!   connection:
    //!
    //!   ```toml
    //!   [dependencies]
    //!   # ...
    //!   actix-session = { version = "...", features = ["redis-rs-session", "redis-rs-tls-session"] }
    //!   ```
    //!
    //! You can implement your own session storage backend using the [`SessionStore`] trait.
    //!
    //! [`SessionStore`]: storage::SessionStore
    //! [`CookieSessionStore`]: storage::CookieSessionStore
    //! [`RedisSessionStore`]: storage::RedisSessionStore
    //! [`RedisActorSessionStore`]: storage::RedisActorSessionStore

    #![deny(rust_2018_idioms, nonstandard_style)]
    #![warn(future_incompatible, missing_docs)]
    #![doc(html_logo_url = "https://actix.rs/img/logo.png")]
    #![doc(html_favicon_url = "https://actix.rs/favicon.ico")]
    #![cfg_attr(docsrs, feature(doc_cfg))]

    mod middleware;
    mod session;
    mod session_ext;
    pub mod storage;

    pub use self::middleware::{
        CookieContentSecurity, SessionLength, SessionMiddleware, SessionMiddlewareBuilder,
    };
    pub use self::session::{Session, SessionStatus};
    pub use self::session_ext::SessionExt;

    #[cfg(test)]
    pub mod test_helpers {
        use actix_web::cookie::Key;
        use rand::{distributions::Alphanumeric, thread_rng, Rng};

        use crate::{storage::SessionStore, CookieContentSecurity};

        /// Generate a random cookie signing/encryption key.
        pub fn key() -> Key {
            let signing_key: String = thread_rng()
                .sample_iter(&Alphanumeric)
                .take(64)
                .map(char::from)
                .collect();
            Key::from(signing_key.as_bytes())
        }

        /// A ready-to-go acceptance test suite to verify that sessions behave as expected
        /// regardless of the underlying session store.
        ///
        /// `is_invalidation_supported` must be set to `true` if the backend supports
        /// "remembering" that a session has been invalidated (e.g. by logging out).
        /// It should be to `false` if the backend allows multiple cookies to be active
        /// at the same time (e.g. cookie store backend).
        pub async fn acceptance_test_suite<F, Store>(store_builder: F, is_invalidation_supported: bool)
        where
            Store: SessionStore + 'static,
            F: Fn() -> Store + Clone + Send + 'static,
        {
            for policy in &[
                CookieContentSecurity::Signed,
                CookieContentSecurity::Private,
            ] {
                println!("Using {:?} as cookie content security policy.", policy);
                acceptance_tests::basic_workflow(store_builder.clone(), *policy).await;
                acceptance_tests::expiration_is_refreshed_on_changes(store_builder.clone(), *policy)
                    .await;
                acceptance_tests::complex_workflow(
                    store_builder.clone(),
                    is_invalidation_supported,
                    *policy,
                )
                .await;
                acceptance_tests::guard(store_builder.clone(), *policy).await;
            }
        }

        mod acceptance_tests {
            use actix_web::{
                dev::Service,
                guard, middleware, test,
                web::{self, get, post, resource, Bytes},
                App, HttpResponse, Result,
            };
            use serde::{Deserialize, Serialize};
            use serde_json::json;
            use time::Duration;

            use crate::{
                middleware::SessionLength, storage::SessionStore, test_helpers::key,
                CookieContentSecurity, Session, SessionExt, SessionMiddleware,
            };

            pub(super) async fn basic_workflow<F, Store>(
                store_builder: F,
                policy: CookieContentSecurity,
            ) where
                Store: SessionStore + 'static,
                F: Fn() -> Store + Clone + Send + 'static,
            {
                let app = test::init_service(
                    App::new()
                        .wrap(
                            SessionMiddleware::builder(store_builder(), key())
                                .cookie_path("/test/".into())
                                .cookie_name("actix-test".into())
                                .cookie_domain(Some("localhost".into()))
                                .cookie_content_security(policy)
                                .session_length(SessionLength::Predetermined {
                                    max_session_length: Some(time::Duration::seconds(100)),
                                })
                                .build(),
                        )
                        .service(web::resource("/").to(|ses: Session| async move {
                            let _ = ses.insert("counter", 100);
                            "test"
                        }))
                        .service(web::resource("/test/").to(|ses: Session| async move {
                            let val: usize = ses.get("counter").unwrap().unwrap();
                            format!("counter: {}", val)
                        })),
                )
                .await;

                let request = test::TestRequest::get().to_request();
                let response = app.call(request).await.unwrap();
                let cookie = response
                    .response()
                    .cookies()
                    .find(|c| c.name() == "actix-test")
                    .unwrap()
                    .clone();
                assert_eq!(cookie.path().unwrap(), "/test/");

                let request = test::TestRequest::with_uri("/test/")
                    .cookie(cookie)
                    .to_request();
                let body = test::call_and_read_body(&app, request).await;
                assert_eq!(body, Bytes::from_static(b"counter: 100"));
            }

            pub(super) async fn expiration_is_refreshed_on_changes<F, Store>(
                store_builder: F,
                policy: CookieContentSecurity,
            ) where
                Store: SessionStore + 'static,
                F: Fn() -> Store + Clone + Send + 'static,
            {
                let app = test::init_service(
                    App::new()
                        .wrap(
                            SessionMiddleware::builder(store_builder(), key())
                                .cookie_content_security(policy)
                                .session_length(SessionLength::Predetermined {
                                    max_session_length: Some(time::Duration::seconds(60)),
                                })
                                .build(),
                        )
                        .service(web::resource("/").to(|ses: Session| async move {
                            let _ = ses.insert("counter", 100);
                            "test"
                        }))
                        .service(web::resource("/test/").to(|| async move { "no-changes-in-session" })),
                )
                .await;

                let request = test::TestRequest::get().to_request();
                let response = app.call(request).await.unwrap();
                let cookie_1 = response
                    .response()
                    .cookies()
                    .find(|c| c.name() == "id")
                    .expect("Cookie is set");
                assert_eq!(cookie_1.max_age(), Some(Duration::seconds(60)));

                let request = test::TestRequest::with_uri("/test/").to_request();
                let response = app.call(request).await.unwrap();
                assert!(response.response().cookies().next().is_none());

                let request = test::TestRequest::get().to_request();
                let response = app.call(request).await.unwrap();
                let cookie_2 = response
                    .response()
                    .cookies()
                    .find(|c| c.name() == "id")
                    .expect("Cookie is set");
                assert_eq!(cookie_2.max_age(), Some(Duration::seconds(60)));
            }

            pub(super) async fn guard<F, Store>(store_builder: F, policy: CookieContentSecurity)
            where
                Store: SessionStore + 'static,
                F: Fn() -> Store + Clone + Send + 'static,
            {
                let srv = actix_test::start(move || {
                    App::new()
                        .wrap(
                            SessionMiddleware::builder(store_builder(), key())
                                .cookie_name("test-session".into())
                                .cookie_content_security(policy)
                                .session_length(SessionLength::Predetermined {
                                    max_session_length: Some(time::Duration::days(7)),
                                })
                                .build(),
                        )
                        .wrap(middleware::Logger::default())
                        .service(resource("/").route(get().to(index)))
                        .service(resource("/do_something").route(post().to(do_something)))
                        .service(resource("/login").route(post().to(login)))
                        .service(resource("/logout").route(post().to(logout)))
                        .service(
                            web::scope("/protected")
                                .guard(guard::fn_guard(|g| {
                                    g.get_session().get::<String>("user_id").unwrap().is_some()
                                }))
                                .service(resource("/count").route(get().to(count))),
                        )
                });

                // Step 1: GET without session info
                //   - response should be a unsuccessful status
                let req_1 = srv.get("/protected/count").send();
                let resp_1 = req_1.await.unwrap();
                assert!(!resp_1.status().is_success());

                // Step 2: POST to login
                //   - set-cookie actix-session will be in response  (session cookie #1)
                //   - updates session state: {"counter": 0, "user_id": "ferris"}
                let req_2 = srv.post("/login").send_json(&json!({"user_id": "ferris"}));
                let resp_2 = req_2.await.unwrap();
                let cookie_1 = resp_2
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();

                // Step 3: POST to do_something
                //   - adds new session state:  {"counter": 1, "user_id": "ferris" }
                //   - set-cookie actix-session should be in response (session cookie #2)
                //   - response should be: {"counter": 1, "user_id": None}
                let req_3 = srv.post("/do_something").cookie(cookie_1.clone()).send();
                let mut resp_3 = req_3.await.unwrap();
                let result_3 = resp_3.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_3,
                    IndexResponse {
                        user_id: Some("ferris".into()),
                        counter: 1
                    }
                );
                let cookie_2 = resp_3
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();

                // Step 4: GET using a existing user id
                //   - response should be: {"counter": 3, "user_id": "ferris"}
                let req_4 = srv.get("/protected/count").cookie(cookie_2.clone()).send();
                let mut resp_4 = req_4.await.unwrap();
                let result_4 = resp_4.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_4,
                    IndexResponse {
                        user_id: Some("ferris".into()),
                        counter: 1
                    }
                );
            }

            pub(super) async fn complex_workflow<F, Store>(
                store_builder: F,
                is_invalidation_supported: bool,
                policy: CookieContentSecurity,
            ) where
                Store: SessionStore + 'static,
                F: Fn() -> Store + Clone + Send + 'static,
            {
                let srv = actix_test::start(move || {
                    App::new()
                        .wrap(
                            SessionMiddleware::builder(store_builder(), key())
                                .cookie_name("test-session".into())
                                .cookie_content_security(policy)
                                .session_length(SessionLength::Predetermined {
                                    max_session_length: Some(time::Duration::days(7)),
                                })
                                .build(),
                        )
                        .wrap(middleware::Logger::default())
                        .service(resource("/").route(get().to(index)))
                        .service(resource("/do_something").route(post().to(do_something)))
                        .service(resource("/login").route(post().to(login)))
                        .service(resource("/logout").route(post().to(logout)))
                });

                // Step 1:  GET index
                //   - set-cookie actix-session should NOT be in response (session data is empty)
                //   - response should be: {"counter": 0, "user_id": None}
                let req_1a = srv.get("/").send();
                let mut resp_1 = req_1a.await.unwrap();
                assert!(resp_1.cookies().unwrap().is_empty());
                let result_1 = resp_1.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_1,
                    IndexResponse {
                        user_id: None,
                        counter: 0
                    }
                );

                // Step 2: POST to do_something
                //   - adds new session state in redis:  {"counter": 1}
                //   - set-cookie actix-session should be in response (session cookie #1)
                //   - response should be: {"counter": 1, "user_id": None}
                let req_2 = srv.post("/do_something").send();
                let mut resp_2 = req_2.await.unwrap();
                let result_2 = resp_2.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_2,
                    IndexResponse {
                        user_id: None,
                        counter: 1
                    }
                );
                let cookie_1 = resp_2
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();
                assert_eq!(cookie_1.max_age(), Some(Duration::days(7)));

                // Step 3:  GET index, including session cookie #1 in request
                //   - set-cookie will *not* be in response
                //   - response should be: {"counter": 1, "user_id": None}
                let req_3 = srv.get("/").cookie(cookie_1.clone()).send();
                let mut resp_3 = req_3.await.unwrap();
                assert!(resp_3.cookies().unwrap().is_empty());
                let result_3 = resp_3.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_3,
                    IndexResponse {
                        user_id: None,
                        counter: 1
                    }
                );

                // Step 4: POST again to do_something, including session cookie #1 in request
                //   - set-cookie will be in response (session cookie #2)
                //   - updates session state:  {"counter": 2}
                //   - response should be: {"counter": 2, "user_id": None}
                let req_4 = srv.post("/do_something").cookie(cookie_1.clone()).send();
                let mut resp_4 = req_4.await.unwrap();
                let result_4 = resp_4.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_4,
                    IndexResponse {
                        user_id: None,
                        counter: 2
                    }
                );
                let cookie_2 = resp_4
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();
                assert_eq!(cookie_2.max_age(), Some(Duration::days(7)));

                // Step 5: POST to login, including session cookie #2 in request
                //   - set-cookie actix-session will be in response  (session cookie #3)
                //   - updates session state: {"counter": 2, "user_id": "ferris"}
                let req_5 = srv
                    .post("/login")
                    .cookie(cookie_2.clone())
                    .send_json(&json!({"user_id": "ferris"}));
                let mut resp_5 = req_5.await.unwrap();
                let cookie_3 = resp_5
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();
                assert_ne!(cookie_2.value(), cookie_3.value());

                let result_5 = resp_5.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_5,
                    IndexResponse {
                        user_id: Some("ferris".into()),
                        counter: 2
                    }
                );

                // Step 6: GET index, including session cookie #3 in request
                //   - response should be: {"counter": 2, "user_id": "ferris"}
                let req_6 = srv.get("/").cookie(cookie_3.clone()).send();
                let mut resp_6 = req_6.await.unwrap();
                let result_6 = resp_6.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_6,
                    IndexResponse {
                        user_id: Some("ferris".into()),
                        counter: 2
                    }
                );

                // Step 7: POST again to do_something, including session cookie #3 in request
                //   - updates session state: {"counter": 3, "user_id": "ferris"}
                //   - response should be: {"counter": 3, "user_id": "ferris"}
                let req_7 = srv.post("/do_something").cookie(cookie_3.clone()).send();
                let mut resp_7 = req_7.await.unwrap();
                let result_7 = resp_7.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_7,
                    IndexResponse {
                        user_id: Some("ferris".into()),
                        counter: 3
                    }
                );

                // Step 8: GET index, including session cookie #2 in request
                // If invalidation is supported, no state will be found associated to this session.
                // If invalidation is not supported, the old state will still be retrieved.
                let req_8 = srv.get("/").cookie(cookie_2.clone()).send();
                let mut resp_8 = req_8.await.unwrap();
                if is_invalidation_supported {
                    assert!(resp_8.cookies().unwrap().is_empty());
                    let result_8 = resp_8.json::<IndexResponse>().await.unwrap();
                    assert_eq!(
                        result_8,
                        IndexResponse {
                            user_id: None,
                            counter: 0
                        }
                    );
                } else {
                    let result_8 = resp_8.json::<IndexResponse>().await.unwrap();
                    assert_eq!(
                        result_8,
                        IndexResponse {
                            user_id: None,
                            counter: 2
                        }
                    );
                }

                // Step 9: POST to logout, including session cookie #3
                //   - set-cookie actix-session will be in response with session cookie #3
                //     invalidation logic
                let req_9 = srv.post("/logout").cookie(cookie_3.clone()).send();
                let resp_9 = req_9.await.unwrap();
                let cookie_3 = resp_9
                    .cookies()
                    .unwrap()
                    .clone()
                    .into_iter()
                    .find(|c| c.name() == "test-session")
                    .unwrap();
                assert_eq!(0, cookie_3.max_age().map(|t| t.whole_seconds()).unwrap());
                assert_eq!("/", cookie_3.path().unwrap());

                // Step 10: GET index, including session cookie #3 in request
                //   - set-cookie actix-session should NOT be in response if invalidation is supported
                //   - response should be: {"counter": 0, "user_id": None}
                let req_10 = srv.get("/").cookie(cookie_3.clone()).send();
                let mut resp_10 = req_10.await.unwrap();
                if is_invalidation_supported {
                    assert!(resp_10.cookies().unwrap().is_empty());
                }
                let result_10 = resp_10.json::<IndexResponse>().await.unwrap();
                assert_eq!(
                    result_10,
                    IndexResponse {
                        user_id: None,
                        counter: 0
                    }
                );
            }

            #[derive(Serialize, Deserialize, Debug, PartialEq)]
            pub struct IndexResponse {
                user_id: Option<String>,
                counter: i32,
            }

            async fn index(session: Session) -> Result<HttpResponse> {
                let user_id: Option<String> = session.get::<String>("user_id").unwrap();
                let counter: i32 = session
                    .get::<i32>("counter")
                    .unwrap_or(Some(0))
                    .unwrap_or(0);

                Ok(HttpResponse::Ok().json(&IndexResponse { user_id, counter }))
            }

            async fn do_something(session: Session) -> Result<HttpResponse> {
                let user_id: Option<String> = session.get::<String>("user_id").unwrap();
                let counter: i32 = session
                    .get::<i32>("counter")
                    .unwrap_or(Some(0))
                    .map_or(1, |inner| inner + 1);
                session.insert("counter", &counter)?;

                Ok(HttpResponse::Ok().json(&IndexResponse { user_id, counter }))
            }

            async fn count(session: Session) -> Result<HttpResponse> {
                let user_id: Option<String> = session.get::<String>("user_id").unwrap();
                let counter: i32 = session.get::<i32>("counter").unwrap().unwrap();

                Ok(HttpResponse::Ok().json(&IndexResponse { user_id, counter }))
            }

            #[derive(Deserialize)]
            struct Identity {
                user_id: String,
            }

            async fn login(user_id: web::Json<Identity>, session: Session) -> Result<HttpResponse> {
                let id = user_id.into_inner().user_id;
                session.insert("user_id", &id)?;
                session.renew();

                let counter: i32 = session
                    .get::<i32>("counter")
                    .unwrap_or(Some(0))
                    .unwrap_or(0);

                Ok(HttpResponse::Ok().json(&IndexResponse {
                    user_id: Some(id),
                    counter,
                }))
            }

            async fn logout(session: Session) -> Result<HttpResponse> {
                let id: Option<String> = session.get("user_id")?;

                let body = if let Some(x) = id {
                    session.purge();
                    format!("Logged out: {}", x)
                } else {
                    "Could not log out anonymous user".to_owned()
                };

                Ok(HttpResponse::Ok().body(body))
            }
        }
    }