rustlavel-cli 0.2.2

//! Signing in, and the several ways it can go wrong.

use rustlavel::prelude::*;

use crate::models::login_attempt::LoginAttempt;
use crate::models::user::User;
use crate::support::{lockout, page, tokens};

/// The session key holding a half-finished login: password accepted, second
/// factor still owed. It is deliberately not the identity key — a session
/// carrying this is not signed in, and nothing downstream should think it is.
pub const PENDING_KEY: &str = "_mfa_pending";

pub struct LoginController;

impl LoginController {
    pub async fn show(req: Request) -> Result<Response> {
        if req.identity().is_some() {
            return Ok(Response::redirect("/dashboard"));
        }
        let context = page::shell(&req, "").await.with(
            "registration_open",
            Json::from(req.config().bool("auth.registration.open", true)),
        );
        req.view("auth/login", &page::old(context, &[("email", None)]))
    }

    pub async fn store(mut req: Request) -> Result<Response> {
        let db = req.state::<Database>().expect("the database is registered in main.rs").clone();
        let email = req.input("email").unwrap_or_default().trim().to_lowercase();
        let password = req.input("password").unwrap_or_default();
        let now = tokens::now();

        // The address limit is checked before anything is looked up, so a
        // password-spraying run is stopped before it can tell one account
        // apart from another.
        if lockout::address_is_blocked(&req).await {
            LoginAttempt::record(&db, &email, None, false, Some("address_blocked"), &req).await?;
            return Self::refuse(req, &email, "Too many failed attempts from this network. Try again later.").await;
        }

        let user = User::first(&db, User::by_email(&email)).await?;

        // The password is verified even when no account matched, against a
        // dummy hash. Skipping it would make a missing account measurably
        // faster to reject than a wrong password, and that difference is how
        // an attacker enumerates who has an account here.
        let stored = user.as_ref().and_then(|u| u.password_hash.clone());
        let matches = match &stored {
            Some(hash) => rustlavel::auth::verify_password(&password, hash),
            None => {
                rustlavel::auth::verify_password(&password, DUMMY_HASH);
                false
            }
        };

        let Some(mut user) = user else {
            LoginAttempt::record(&db, &email, None, false, Some("unknown_email"), &req).await?;
            lockout::record_address_failure(&req).await;
            return Self::refuse(req, &email, WRONG).await;
        };

        if let Err(reason) = user.can_sign_in(&now) {
            LoginAttempt::record(&db, &email, Some(user.id), false, Some(reason), &req).await?;

            // A locked account is told it is locked. Hiding that would leave a
            // person retrying a correct password forever with no idea why.
            if reason == "locked" {
                let until = user.locked_until.clone().unwrap_or_default();
                let context = page::shell(&req, "").await
                    .with("locked", Json::from(true))
                    .with("locked_for", Json::from(lockout::remaining(&until, &now)));
                return req.view("auth/login", &page::old(context, &[("email", Some(email))]));
            }
            let message = match reason {
                "not_activated" => "This account has not been activated yet. Check your email for the invitation.",
                _ => "This account has been deactivated. Ask an administrator.",
            };
            return Self::refuse(req, &email, message).await;
        }

        if !matches {
            LoginAttempt::record(&db, &email, Some(user.id), false, Some("bad_password"), &req).await?;
            lockout::record_address_failure(&req).await;

            if lockout::record_failure(&db, &mut user, &now).await? {
                let until = user.locked_until.clone().unwrap_or_default();
                let context = page::shell(&req, "").await
                    .with("locked", Json::from(true))
                    .with("locked_for", Json::from(lockout::remaining(&until, &now)));
                return req.view("auth/login", &page::old(context, &[("email", Some(email))]));
            }
            return Self::refuse(req, &email, WRONG).await;
        }

        // The password was right. If a second factor is enrolled, the session
        // holds only a pending id — not an identity — until it is satisfied.
        if crate::controllers::auth::mfa_controller::has_factor(&db, user.id).await? {
            let session = req.session();
            session.regenerate();
            session.put(PENDING_KEY, Json::from(user.id));
            return Ok(Response::see_other("/mfa"));
        }

        Self::complete(&req, &db, &mut user, &now).await?;
        Ok(Response::see_other(intended(&req)))
    }

    /// Finish a login that has cleared every check.
    pub async fn complete(req: &Request, db: &Database, user: &mut User, now: &str) -> Result<()> {
        Guard::new(req.session().clone()).login(user);
        lockout::record_success(db, user, req, now).await?;
        LoginAttempt::record(db, &user.email.clone(), Some(user.id), true, None, req).await?;
        Ok(())
    }

    pub async fn destroy(req: Request) -> Result<Response> {
        Guard::new(req.session().clone()).logout();
        Ok(Response::see_other("/login"))
    }

    /// Re-render the form with a message, keeping the address but never the
    /// password.
    async fn refuse(req: Request, email: &str, message: &str) -> Result<Response> {
        let context = page::shell(&req, "").await
            .with("error_summary", Json::from(message))
            .with("registration_open", Json::from(req.config().bool("auth.registration.open", true)));
        req.view("auth/login", &page::old(context, &[("email", Some(email.to_string()))]))
    }
}

/// One message for a wrong password and for an address with no account.
///
/// Saying which would turn the login form into a directory of who has an
/// account here, which matters for any site where membership itself is
/// private.
const WRONG: &str = "Those details do not match an account.";

/// A real argon2 hash of a value nobody knows, so the no-account path costs
/// the same as the wrong-password path.
const DUMMY_HASH: &str = "$argon2id$v=19$m=19456,t=2,p=1$c29tZXNhbHR2YWx1ZQ$Zm9yIHRpbWluZyBvbmx5IG5ldmVyIG1hdGNoZXM";

/// Where to go after signing in: back where they were headed, if anywhere.
fn intended(req: &Request) -> String {
    req.session()
        .forget("_intended")
        .and_then(|value| value.as_str().map(str::to_string))
        // Only a path on this site. A full URL here would be an open redirect,
        // which is how a phishing link borrows a real domain.
        .filter(|path| path.starts_with('/') && !path.starts_with("//"))
        .unwrap_or_else(|| "/dashboard".to_string())
}