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path: root/server/src/logic/session.rs
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/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2025 metamuffin <metamuffin.org>
*/
use crate::ui::error::MyError;
use aes_gcm_siv::{
    aead::{generic_array::GenericArray, Aead},
    KeyInit,
};
use anyhow::anyhow;
use base64::Engine;
use chrono::{DateTime, Duration, Utc};
use jellybase::{database::Database, SECRETS};
use jellycommon::user::{PermissionSet, User};
use log::warn;
use rocket::{
    async_trait,
    http::Status,
    outcome::Outcome,
    request::{self, FromRequest},
    Request, State,
};
use serde::{Deserialize, Serialize};
use std::sync::LazyLock;

pub struct Session {
    pub user: User,
}

pub struct AdminSession(pub Session);

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionData {
    username: String,
    expire: DateTime<Utc>,
    permissions: PermissionSet,
}

impl Session {
    pub async fn from_request_ut(req: &Request<'_>) -> Result<Self, MyError> {
        let username;

        #[cfg(not(feature = "bypass-auth"))]
        {
            let token = req
                .query_value("session")
                .map(|e| e.unwrap())
                .or_else(|| req.query_value("api_key").map(|e| e.unwrap()))
                .or_else(|| req.headers().get_one("X-MediaBrowser-Token"))
                .or_else(|| {
                    req.headers()
                        .get_one("Authorization")
                        .and_then(parse_jellyfin_auth)
                }) // for jellyfin compat
                .or(req.cookies().get("session").map(|cookie| cookie.value()))
                .ok_or(anyhow!("not logged in"))?;

            // jellyfin urlescapes the token for *some* requests
            let token = token.replace("%3D", "=");
            username = validate(&token)?;
        };

        #[cfg(feature = "bypass-auth")]
        {
            parse_jellyfin_auth("a"); // unused warning is annoying
            username = "admin".to_string();
        }

        let db = req.guard::<&State<Database>>().await.unwrap();

        let user = db.get_user(&username)?.ok_or(anyhow!("user not found"))?;

        Ok(Session { user })
    }
}

fn parse_jellyfin_auth(h: &str) -> Option<&str> {
    for tok in h.split(" ") {
        if let Some(tok) = tok.strip_prefix("Token=\"") {
            if let Some(tok) = tok.strip_suffix("\"") {
                return Some(tok);
            }
        }
    }
    None
}

#[async_trait]
impl<'r> FromRequest<'r> for Session {
    type Error = MyError;
    async fn from_request<'life0>(
        request: &'r Request<'life0>,
    ) -> request::Outcome<Self, Self::Error> {
        match Session::from_request_ut(request).await {
            Ok(x) => Outcome::Success(x),
            Err(e) => {
                warn!("authentificated route rejected: {e:?}");
                Outcome::Forward(Status::Unauthorized)
            }
        }
    }
}

#[async_trait]
impl<'r> FromRequest<'r> for AdminSession {
    type Error = MyError;
    async fn from_request<'life0>(
        request: &'r Request<'life0>,
    ) -> request::Outcome<Self, Self::Error> {
        match Session::from_request_ut(request).await {
            Ok(x) => {
                if x.user.admin {
                    Outcome::Success(AdminSession(x))
                } else {
                    Outcome::Error((
                        Status::Unauthorized,
                        MyError(anyhow!("you are not an admin")),
                    ))
                }
            }
            Err(e) => {
                warn!("authentificated route rejected: {e:?}");
                Outcome::Forward(Status::Unauthorized)
            }
        }
    }
}

static SESSION_KEY: LazyLock<[u8; 32]> = LazyLock::new(|| {
    if let Some(sk) = &SECRETS.session_key {
        let r = base64::engine::general_purpose::STANDARD
            .decode(sk)
            .expect("key invalid; should be valid base64");
        r.try_into()
            .expect("key has the wrong length; should be 32 bytes")
    } else {
        warn!("session_key not configured; generating a random one.");
        [(); 32].map(|_| rand::random())
    }
});

pub fn create(username: String, permissions: PermissionSet, expire: Duration) -> String {
    let session_data = SessionData {
        expire: Utc::now() + expire,
        username: username.to_owned(),
        permissions,
    };
    let mut plaintext =
        bincode::serde::encode_to_vec(&session_data, bincode::config::standard()).unwrap();

    while plaintext.len() % 16 == 0 {
        plaintext.push(0);
    }

    let cipher = aes_gcm_siv::Aes256GcmSiv::new_from_slice(&*SESSION_KEY).unwrap();
    let nonce = [(); 12].map(|_| rand::random());
    let mut ciphertext = cipher
        .encrypt(&GenericArray::from(nonce), plaintext.as_slice())
        .unwrap();
    ciphertext.extend(nonce);

    base64::engine::general_purpose::URL_SAFE.encode(&ciphertext)
}

pub fn validate(token: &str) -> anyhow::Result<String> {
    let ciphertext = base64::engine::general_purpose::URL_SAFE.decode(token)?;
    let cipher = aes_gcm_siv::Aes256GcmSiv::new_from_slice(&*SESSION_KEY).unwrap();
    let (ciphertext, nonce) = ciphertext.split_at(ciphertext.len() - 12);
    let plaintext = cipher
        .decrypt(nonce.into(), ciphertext)
        .map_err(|e| anyhow!("decryption failed: {e:?}"))?;

    let (session_data, _): (SessionData, _) =
        bincode::serde::decode_from_slice(&plaintext, bincode::config::standard())?;

    if session_data.expire < Utc::now() {
        Err(anyhow!("session expired"))?
    }

    Ok(session_data.username)
}

#[test]
fn test() {
    jellybase::use_test_config();
    let tok = create(
        "blub".to_string(),
        jellycommon::user::PermissionSet::default(),
        Duration::days(1),
    );
    validate(&tok).unwrap();
}

#[test]
fn test_crypto() {
    jellybase::use_test_config();
    let nonce = [(); 12].map(|_| rand::random());
    let cipher = aes_gcm_siv::Aes256GcmSiv::new_from_slice(&*SESSION_KEY).unwrap();
    let plaintext = b"testing stuff---";
    let ciphertext = cipher
        .encrypt(&GenericArray::from(nonce), plaintext.as_slice())
        .unwrap();
    let plaintext2 = cipher
        .decrypt((&nonce).into(), ciphertext.as_slice())
        .unwrap();
    assert_eq!(plaintext, plaintext2.as_slice());
}