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  1. 13
      CHANGELOG.md
  2. 19
      Cargo.toml
  3. 60
      README.md
  4. 59
      examples/dog_list/main.rs
  5. 28
      examples/minimal/main.rs
  6. 73
      examples/visit_counter/main.rs
  7. 332
      src/lib.rs
  8. 206
      src/session.rs

13
CHANGELOG.md
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@ -1,13 +0,0 @@
# [0.3.0]
- Update dependencies
- Added new example
- Port to rocket `0.5.0-rc.2`
# [0.2.2]
- Update dependencies
# [0.2.1]
- change from `thread_rng` to `OsRng` for better session ID entropy

19
Cargo.toml
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@ -1,21 +1,12 @@
[package] [package]
name = "rocket_session" name = "rocket_session"
version = "0.3.0" version = "0.1.0"
authors = ["Ondřej Hruška <ondra@ondrovo.com>"] authors = ["Ondřej Hruška <ondra@ondrovo.com>"]
edition = "2021" edition = "2018"
license = "MIT"
description = "Rocket.rs plug-in for cookie-based sessions holding arbitrary data"
repository = "https://git.ondrovo.com/packages/rocket_session"
readme = "README.md"
keywords = ["rocket", "rocket-rs", "session", "cookie"]
categories = [
"web-programming",
"web-programming::http-server"
]
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies] [dependencies]
rand = "0.8" rand = "0.7.2"
rocket = "0.5.0-rc.2" rocket = "0.4.2"
parking_lot = "0.12" parking_lot = "0.10.0"

60
README.md
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@ -2,55 +2,31 @@
Adding cookie-based sessions to a rocket application is extremely simple with this crate. Adding cookie-based sessions to a rocket application is extremely simple with this crate.
Sessions are used to share data between related requests, such as user authentication, shopping basket,
form values that failed validation for re-filling, etc.
## Configuration
The implementation is generic to support any type as session data: a custom struct, `String`, The implementation is generic to support any type as session data: a custom struct, `String`,
`HashMap`, or perhaps `serde_json::Value`. You're free to choose. `HashMap`, or perhaps `serde_json::Value`. You're free to choose.
The session lifetime, cookie name, and other parameters can be configured by calling chained The session expiry time is configurable through the Fairing. When a session expires,
methods on the fairing. When a session expires, the data associated with it is dropped. the data associated with it is dropped.
Example: `Session::fairing().with_lifetime(Duration::from_secs(15))`
## Usage
To use session in a route, first make sure you have the fairing attached by calling
`rocket.attach(Session::fairing())` at start-up, and then add something like `session : Session`
to the parameter list of your route(s). Everything else--session init, expiration, cookie
management--is done for you behind the scenes.
Session data is accessed in a closure run in the session context, using the `session.tap()`
method. This closure runs inside a per-session mutex, avoiding simultaneous mutation
from different requests. Try to *avoid lengthy operations inside the closure*,
as it effectively blocks any other request to session-enabled routes by the client.
Every request to a session-enabled route extends the session's lifetime to the full ## Basic example
configured time (defaults to 1 hour). Automatic clean-up removes expired sessions to make sure
the session list does not waste memory.
## Examples
More examples are in the "examples" folder - run with `cargo run --example=NAME`
### Basic Example
This simple example uses u64 as the session variable; note that it can be a struct, map, or anything else, This simple example uses u64 as the session variable; note that it can be a struct, map, or anything else,
it just needs to implement `Send + Sync + Default`. it just needs to implement `Send + Sync + Default`.
```rust ```rust
#[macro_use] #![feature(proc_macro_hygiene, decl_macro)]
extern crate rocket; #[macro_use] extern crate rocket;
type Session<'a> = rocket_session::Session<'a, u64>; use std::time::Duration;
#[launch] // It's convenient to define a type alias:
fn rocket() -> _ { pub type Session<'a> = rocket_session::Session<'a, u64>;
rocket::build()
.attach(Session::fairing()) fn main() {
rocket::ignite()
.attach(Session::fairing(Duration::from_secs(3600)))
.mount("/", routes![index]) .mount("/", routes![index])
.launch();
} }
#[get("/")] #[get("/")]
@ -66,18 +42,14 @@ fn index(session: Session) -> String {
format!("{} visits", count) format!("{} visits", count)
} }
``` ```
## Extending Session by a Trait ## Extending by a trait
The `.tap()` method is powerful, but sometimes you may wish for something more convenient. The `tap` method is powerful, but sometimes you may wish for something more convenient.
Here is an example of using a custom trait and the `json_dotpath` crate to implement Here is an example of using a custom trait and the `json_dotpath` crate to implement
a polymorphic store based on serde serialization. a polymorphic store based on serde serialization:
Note that this approach is prone to data races if you're accessing the session object multiple times per request,
since every method contains its own `.tap()`. It may be safer to simply call the `.dot_*()` methods manually in one shared closure.
```rust ```rust
use serde_json::Value; use serde_json::Value;

59
examples/dog_list/main.rs
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@ -1,59 +0,0 @@
#[macro_use]
extern crate rocket;
use rocket::response::content::RawHtml;
use rocket::response::Redirect;
type Session<'a> = rocket_session::Session<'a, Vec<String>>;
#[launch]
fn rocket() -> _ {
rocket::build()
.attach(Session::fairing())
.mount("/", routes![index, add, remove])
}
#[get("/")]
fn index(session: Session) -> RawHtml<String> {
let mut page = String::new();
page.push_str(
r#"
<!DOCTYPE html>
<h1>My Dogs</h1>
<form method="POST" action="/add">
Add Dog: <input type="text" name="name"> <input type="submit" value="Add">
</form>
<ul>
"#,
);
session.tap(|sess| {
for (n, dog) in sess.iter().enumerate() {
page.push_str(&format!(
r#"<li>&#x1F436; {} <a href="/remove/{}">Remove</a></li>"#,
dog, n
));
}
});
page.push_str("</ul>");
RawHtml(page)
}
#[post("/add", data = "<dog>")]
fn add(session: Session, dog: String) -> Redirect {
session.tap(move |sess| {
sess.push(dog);
});
Redirect::found("/")
}
#[get("/remove/<dog>")]
fn remove(session: Session, dog: usize) -> Redirect {
session.tap(|sess| {
if dog < sess.len() {
sess.remove(dog);
}
});
Redirect::found("/")
}

28
examples/minimal/main.rs
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@ -1,28 +0,0 @@
#[macro_use]
extern crate rocket;
use std::time::Duration;
type Session<'a> = rocket_session::Session<'a, u64>;
#[launch]
fn rocket() -> _ {
// This session expires in 15 seconds as a demonstration of session configuration
rocket::build()
.attach(Session::fairing().with_lifetime(Duration::from_secs(15)))
.mount("/", routes![index])
}
#[get("/")]
fn index(session: Session) -> String {
let count = session.tap(|n| {
// Change the stored value (it is &mut)
*n += 1;
// Return something to the caller.
// This can be any type, 'tap' is generic.
*n
});
format!("{} visits", count)
}

73
examples/visit_counter/main.rs
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@ -1,73 +0,0 @@
//! This demo is a page visit counter, with a custom cookie name, length, and expiry time.
//!
//! The expiry time is set to 10 seconds to illustrate how a session is cleared if inactive.
#[macro_use]
extern crate rocket;
use rocket::response::content::RawHtml;
use std::time::Duration;
#[derive(Default, Clone)]
struct SessionData {
visits1: usize,
visits2: usize,
}
// It's convenient to define a type alias:
type Session<'a> = rocket_session::Session<'a, SessionData>;
#[launch]
fn rocket() -> _ {
rocket::build()
.attach(
Session::fairing()
// 10 seconds of inactivity until session expires
// (wait 10s and refresh, the numbers will reset)
.with_lifetime(Duration::from_secs(10))
// custom cookie name and length
.with_cookie_name("my_cookie")
.with_cookie_len(20),
)
.mount("/", routes![index, about])
}
#[get("/")]
fn index(session: Session) -> RawHtml<String> {
// Here we build the entire response inside the 'tap' closure.
// While inside, the session is locked to parallel changes, e.g.
// from a different browser tab.
session.tap(|sess| {
sess.visits1 += 1;
RawHtml(format!(
r##"
<!DOCTYPE html>
<h1>Home</h1>
<a href="/">Refresh</a> &bull; <a href="/about/">go to About</a>
<p>Visits: home {}, about {}</p>
"##,
sess.visits1, sess.visits2
))
})
}
#[get("/about")]
fn about(session: Session) -> RawHtml<String> {
// Here we return a value from the tap function and use it below
let count = session.tap(|sess| {
sess.visits2 += 1;
sess.visits2
});
RawHtml(format!(
r##"
<!DOCTYPE html>
<h1>About</h1>
<a href="/about">Refresh</a> &bull; <a href="/">go home</a>
<p>Page visits: {}</p>
"##,
count
))
}

332
src/lib.rs
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@ -1,330 +1,2 @@
use std::borrow::Cow; mod session;
use std::collections::HashMap; pub use session::Session;
use std::fmt::{self, Display, Formatter};
use std::marker::PhantomData;
use std::ops::Add;
use std::time::{Duration, Instant};
use parking_lot::{Mutex, RwLock, RwLockUpgradableReadGuard};
use rand::{rngs::OsRng, Rng};
use rocket::{
fairing::{self, Fairing, Info},
http::{Cookie, Status},
outcome::Outcome,
request::FromRequest,
Build, Request, Response, Rocket, State,
};
/// Session store (shared state)
#[derive(Debug)]
pub struct SessionStore<D>
where
D: 'static + Sync + Send + Default,
{
/// The internally mutable map of sessions
inner: RwLock<StoreInner<D>>,
// Session config
config: SessionConfig,
}
/// Session config object
#[derive(Debug, Clone)]
struct SessionConfig {
/// Sessions lifespan
lifespan: Duration,
/// Session cookie name
cookie_name: Cow<'static, str>,
/// Session cookie path
cookie_path: Cow<'static, str>,
/// Session ID character length
cookie_len: usize,
}
impl Default for SessionConfig {
fn default() -> Self {
Self {
lifespan: Duration::from_secs(3600),
cookie_name: "rocket_session".into(),
cookie_path: "/".into(),
cookie_len: 16,
}
}
}
/// Mutable object stored inside SessionStore behind a RwLock
#[derive(Debug)]
struct StoreInner<D>
where
D: 'static + Sync + Send + Default,
{
sessions: HashMap<String, Mutex<SessionInstance<D>>>,
last_expiry_sweep: Instant,
}
impl<D> Default for StoreInner<D>
where
D: 'static + Sync + Send + Default,
{
fn default() -> Self {
Self {
sessions: Default::default(),
// the first expiry sweep is scheduled one lifetime from start-up
last_expiry_sweep: Instant::now(),
}
}
}
/// Session, as stored in the sessions store
#[derive(Debug)]
struct SessionInstance<D>
where
D: 'static + Sync + Send + Default,
{
/// Data object
data: D,
/// Expiry
expires: Instant,
}
/// Session ID newtype for rocket's "local_cache"
#[derive(Clone, Debug)]
struct SessionID(String);
impl SessionID {
fn as_str(&self) -> &str {
self.0.as_str()
}
}
impl Display for SessionID {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
f.write_str(&self.0)
}
}
/// Session instance
///
/// To access the active session, simply add it as an argument to a route function.
///
/// Sessions are started, restored, or expired in the `FromRequest::from_request()` method
/// when a `Session` is prepared for one of the route functions.
#[derive(Debug)]
pub struct Session<'a, D>
where
D: 'static + Sync + Send + Default,
{
/// The shared state reference
store: &'a State<SessionStore<D>>,
/// Session ID
id: &'a SessionID,
}
#[rocket::async_trait]
impl<'r, D> FromRequest<'r> for Session<'r, D>
where
D: 'static + Sync + Send + Default,
{
type Error = ();
async fn from_request(request: &'r Request<'_>) -> Outcome<Self, (Status, Self::Error), ()> {
let store = request.guard::<&State<SessionStore<D>>>().await.unwrap();
Outcome::Success(Session {
id: request.local_cache(|| {
let store_ug = store.inner.upgradable_read();
// Resolve session ID
let id = request
.cookies()
.get(&store.config.cookie_name)
.map(|cookie| SessionID(cookie.value().to_string()));
let expires = Instant::now().add(store.config.lifespan);
if let Some(m) = id
.as_ref()
.and_then(|token| store_ug.sessions.get(token.as_str()))
{
// --- ID obtained from a cookie && session found in the store ---
let mut inner = m.lock();
if inner.expires <= Instant::now() {
// Session expired, reuse the ID but drop data.
inner.data = D::default();
}
// Session is extended by making a request with valid ID
inner.expires = expires;
id.unwrap()
} else {
// --- ID missing or session not found ---
// Get exclusive write access to the map
let mut store_wg = RwLockUpgradableReadGuard::upgrade(store_ug);
// This branch runs less often, and we already have write access,
// let's check if any sessions expired. We don't want to hog memory
// forever by abandoned sessions (e.g. when a client lost their cookie)
// Throttle by lifespan - e.g. sweep every hour
if store_wg.last_expiry_sweep.elapsed() > store.config.lifespan {
let now = Instant::now();
store_wg.sessions.retain(|_k, v| v.lock().expires > now);
store_wg.last_expiry_sweep = now;
}
// Find a new unique ID - we are still safely inside the write guard
let new_id = SessionID(loop {
let token: String = OsRng
.sample_iter(&rand::distributions::Alphanumeric)
.take(store.config.cookie_len)
.map(char::from)
.collect();
if !store_wg.sessions.contains_key(&token) {
break token;
}
});
store_wg.sessions.insert(
new_id.to_string(),
Mutex::new(SessionInstance {
data: Default::default(),
expires,
}),
);
new_id
}
}),
store,
})
}
}
impl<'a, D> Session<'a, D>
where
D: 'static + Sync + Send + Default,
{
/// Create the session fairing.
///
/// You can configure the session store by calling chained methods on the returned value
/// before passing it to `rocket.attach()`
pub fn fairing() -> SessionFairing<D> {
SessionFairing::<D>::new()
}
/// Clear session data (replace the value with default)
pub fn clear(&self) {
self.tap(|m| {
*m = D::default();
})
}
/// Access the session's data using a closure.
///
/// The closure is called with the data value as a mutable argument,
/// and can return any value to be is passed up to the caller.
pub fn tap<T>(&self, func: impl FnOnce(&mut D) -> T) -> T {
// Use a read guard, so other already active sessions are not blocked
// from accessing the store. New incoming clients may be blocked until
// the tap() call finishes
let store_rg = self.store.inner.read();
// Unlock the session's mutex.
// Expiry was checked and prolonged at the beginning of the request
let mut instance = store_rg
.sessions
.get(self.id.as_str())
.expect("Session data unexpectedly missing")
.lock();
func(&mut instance.data)
}
}
/// Fairing struct
#[derive(Default)]
pub struct SessionFairing<D>
where
D: 'static + Sync + Send + Default,
{
config: SessionConfig,
phantom: PhantomData<D>,
}
impl<D> SessionFairing<D>
where
D: 'static + Sync + Send + Default,
{
fn new() -> Self {
Self::default()
}
/// Set session lifetime (expiration time).
///
/// Call on the fairing before passing it to `rocket.attach()`
pub fn with_lifetime(mut self, time: Duration) -> Self {
self.config.lifespan = time;
self
}
/// Set session cookie name and length
///
/// Call on the fairing before passing it to `rocket.attach()`
pub fn with_cookie_name(mut self, name: impl Into<Cow<'static, str>>) -> Self {
self.config.cookie_name = name.into();
self
}
/// Set session cookie name and length
///
/// Call on the fairing before passing it to `rocket.attach()`
pub fn with_cookie_len(mut self, length: usize) -> Self {
self.config.cookie_len = length;
self
}
/// Set session cookie name and length
///
/// Call on the fairing before passing it to `rocket.attach()`
pub fn with_cookie_path(mut self, path: impl Into<Cow<'static, str>>) -> Self {
self.config.cookie_path = path.into();
self
}
}
#[rocket::async_trait]
impl<D> Fairing for SessionFairing<D>
where
D: 'static + Sync + Send + Default,
{
fn info(&self) -> Info {
Info {
name: "Session",
kind: fairing::Kind::Ignite | fairing::Kind::Response,
}
}
async fn on_ignite(&self, rocket: Rocket<Build>) -> Result<Rocket<Build>, Rocket<Build>> {
// install the store singleton
Ok(rocket.manage(SessionStore::<D> {
inner: Default::default(),
config: self.config.clone(),
}))
}
async fn on_response<'r>(&self, request: &'r Request<'_>, response: &mut Response) {
// send the session cookie, if session started
let session = request.local_cache(|| SessionID("".to_string()));
if !session.0.is_empty() {
response.adjoin_header(
Cookie::build(self.config.cookie_name.clone(), session.to_string())
.path("/")
.finish(),
);
}
}
}

206
src/session.rs
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@ -0,0 +1,206 @@
use parking_lot::RwLock;
use rand::Rng;
use rocket::{
fairing::{self, Fairing, Info},
http::{Cookie, Status},
request::FromRequest,
Outcome, Request, Response, Rocket, State,
};
use std::collections::HashMap;
use std::marker::PhantomData;
use std::ops::Add;
use std::time::{Duration, Instant};
const SESSION_COOKIE: &str = "SESSID";
const SESSION_ID_LEN: usize = 16;
/// Session, as stored in the sessions store
#[derive(Debug)]
struct SessionInstance<D>
where
D: 'static + Sync + Send + Default,
{
/// Data object
data: D,
/// Expiry
expires: Instant,
}
/// Session store (shared state)
#[derive(Default, Debug)]
pub struct SessionStore<D>
where
D: 'static + Sync + Send + Default,
{
/// The internaly mutable map of sessions
inner: RwLock<HashMap<String, SessionInstance<D>>>,
/// Sessions lifespan
lifespan: Duration,
}
impl<D> SessionStore<D>
where
D: 'static + Sync + Send + Default,
{
/// Remove all expired sessions
pub fn remove_expired(&self) {
let now = Instant::now();
self.inner.write().retain(|_k, v| v.expires > now);
}
}
/// Session ID newtype for rocket's "local_cache"
#[derive(PartialEq, Hash, Clone, Debug)]
struct SessionID(String);
impl<'a, 'r> FromRequest<'a, 'r> for &'a SessionID {
type Error = ();
fn from_request(request: &'a Request<'r>) -> Outcome<Self, (Status, Self::Error), ()> {
Outcome::Success(request.local_cache(|| {
if let Some(cookie) = request.cookies().get(SESSION_COOKIE) {
SessionID(cookie.value().to_string()) // FIXME avoid cloning (cow?)
} else {
SessionID(
rand::thread_rng()
.sample_iter(&rand::distributions::Alphanumeric)
.take(16)
.collect(),
)
}
}))
}
}
/// Session instance
#[derive(Debug)]
pub struct Session<'a, D>
where
D: 'static + Sync + Send + Default,
{
/// The shared state reference
store: State<'a, SessionStore<D>>,
/// Session ID
id: &'a SessionID,
}
impl<'a, 'r, D> FromRequest<'a, 'r> for Session<'a, D>
where
D: 'static + Sync + Send + Default,
{
type Error = ();
fn from_request(request: &'a Request<'r>) -> Outcome<Self, (Status, Self::Error), ()> {
Outcome::Success(Session {
id: request.local_cache(|| {
if let Some(cookie) = request.cookies().get(SESSION_COOKIE) {
SessionID(cookie.value().to_string())
} else {
SessionID(
rand::thread_rng()
.sample_iter(&rand::distributions::Alphanumeric)
.take(SESSION_ID_LEN)
.collect(),
)
}
}),
store: request.guard().unwrap(),
})
}
}
impl<'a, D> Session<'a, D>
where
D: 'static + Sync + Send + Default,
{
/// Get the fairing object
pub fn fairing(lifespan: Duration) -> impl Fairing {
SessionFairing::<D> {
lifespan,
_phantom: PhantomData,
}
}
/// Access the session store
pub fn get_store(&self) -> &SessionStore<D> {
&self.store
}
/// Set the session object to its default state
pub fn reset(&self) {
self.tap(|m| {
*m = D::default();
})
}
/// Renew the session without changing any data
pub fn renew(&self) {
self.tap(|_| ())
}
/// Run a closure with a mutable reference to the session object.
/// The closure's return value is send to the caller.
pub fn tap<T>(&self, func: impl FnOnce(&mut D) -> T) -> T {
let mut wg = self.store.inner.write();
if let Some(instance) = wg.get_mut(&self.id.0) {
// wipe session data if expired
if instance.expires <= Instant::now() {
instance.data = D::default();
}
// update expiry timestamp
instance.expires = Instant::now().add(self.store.lifespan);
func(&mut instance.data)
} else {
// no object in the store yet, start fresh
let mut data = D::default();
let result = func(&mut data);
wg.insert(
self.id.0.clone(),
SessionInstance {
data,
expires: Instant::now().add(self.store.lifespan),
},
);
result
}
}
}
/// Fairing struct
struct SessionFairing<D>
where
D: 'static + Sync + Send + Default,
{
lifespan: Duration,
_phantom: PhantomData<D>,
}
impl<D> Fairing for SessionFairing<D>
where
D: 'static + Sync + Send + Default,
{
fn info(&self) -> Info {
Info {
name: "Session",
kind: fairing::Kind::Attach | fairing::Kind::Response,
}
}
fn on_attach(&self, rocket: Rocket) -> Result<Rocket, Rocket> {
Ok(rocket.manage(SessionStore::<D> {
inner: Default::default(),
lifespan: self.lifespan,
}))
}
fn on_response<'r>(&self, request: &'r Request, response: &mut Response) {
let session = request.local_cache(|| SessionID("".to_string()));
if !session.0.is_empty() {
response.adjoin_header(Cookie::build(SESSION_COOKIE, session.0.clone()).finish());
}
}
}
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