identity: created initial did:web server (#123)

* Adds create POST method (accepts pub key, redirects to new URL)
* Adds read GET method (retrieves JWK from user's url)
* Handles serialization of JWK
* Testable/mockable UUID generation.

Known issues:
* Not actually compliant with did:web yet. We are supposed to return a
did:document, but right now we return a Json Web Key
* We don't do any auth on the endpoints yet
* We don't use any persistent storage (no db)
* We totally fake the returned pub key. I.e. we actually don't use the
pub key from the POST at all yet.

Cargo.toml

@@ -1,6 +1,7 @@
 [workspace]
 resolver = "2"
 members = [
+	"apps/identity_server",
 	"apps/legacy_web/backend",
 	"apps/legacy_web/frontend",
 	"apps/networked_physics_demo/client",
@@ -29,6 +30,7 @@ rust-version = "1.78.0"
 
 [workspace.dependencies]
 async-compat = "0.2.4"
+axum = "0.7.5"
 base64 = "0.21.7"
 bevy = { version = "0.13", features = ["serialize"] }
 bevy-inspector-egui = "0.23.4"
@@ -47,15 +49,19 @@ bevy_web_asset = { git = "https://github.com/Schmarni-Dev/bevy_web_asset", rev =
 bytes = "1.5.0"
 clap = { version = "4.4.11", features = ["derive"] }
 color-eyre = "0.6"
+did-simple.path = "crates/did-simple"
 egui = "0.26"
 egui-picking = { path = "crates/egui-picking" }
 eyre = "0.6"
 futures = "0.3.30"
+hex-literal = "0.4.1"
+jose-jwk = { version = "0.1.2", default-features = false }
 lightyear = "0.12"
 openxr = "0.18"
 picking-xr = { path = "crates/picking-xr" }
 pin-project = "1"
 rand = "0.8.5"
+rand_chacha = "0.3.1"
 rand_xoshiro = "0.6.0"
 random-number = "0.1.8"
 replicate-client.path = "crates/replicate/client"
@@ -69,6 +75,7 @@ thiserror = "1.0.56"
 tokio = { version = "1.35.1", default-features = false }
 tokio-serde = "0.9"
 tokio-util = { version = "0.7.10", default-features = true }
+tower-http = "0.5.2"
 tracing = "0.1.40"
 tracing-subscriber = "0.3.18"
 url = "2.5.0"

apps/identity_server/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "identity_server"
+version.workspace = true
+license.workspace = true
+repository.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "Self-custodial identity using did:web"
+publish = false
+
+[dependencies]
+axum.workspace = true
+clap.workspace = true
+color-eyre.workspace = true
+did-simple.workspace = true
+jose-jwk = { workspace = true, default-features = false }
+rand.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+tokio = { workspace = true, features = ["full"] }
+tower-http = { workspace = true, features = ["trace"] }
+tracing-subscriber = { workspace = true, features = ["env-filter"] }
+tracing.workspace = true
+uuid = { workspace = true, features = ["std", "v4", "serde"] }
+
+[dev-dependencies]
+base64.workspace = true
+hex-literal.workspace = true

apps/identity_server/src/lib.rs

@@ -0,0 +1,21 @@
+mod uuid;
+pub mod v1;
+
+use axum::routing::get;
+use tower_http::trace::TraceLayer;
+
+/// Main router of API
+pub fn router() -> axum::Router<()> {
+	let v1_router = crate::v1::RouterConfig {
+		..Default::default()
+	}
+	.build();
+	axum::Router::new()
+		.route("/", get(root))
+		.nest("/api/v1", v1_router)
+		.layer(TraceLayer::new_for_http())
+}
+
+async fn root() -> &'static str {
+	"uwu hewwo this api is under constwuction"
+}

apps/identity_server/src/main.rs

@@ -0,0 +1,33 @@
+use std::net::{Ipv6Addr, SocketAddr};
+
+use clap::Parser as _;
+use tracing::info;
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter};
+
+#[derive(clap::Parser, Debug)]
+struct Cli {
+	#[clap(default_value = "0")]
+	port: u16,
+}
+
+#[tokio::main]
+async fn main() -> color_eyre::Result<()> {
+	color_eyre::install()?;
+	tracing_subscriber::registry()
+		.with(EnvFilter::try_from_default_env().unwrap_or("info".into()))
+		.with(tracing_subscriber::fmt::layer())
+		.init();
+
+	let cli = Cli::parse();
+
+	let listener = tokio::net::TcpListener::bind(SocketAddr::new(
+		Ipv6Addr::UNSPECIFIED.into(),
+		cli.port,
+	))
+	.await
+	.unwrap();
+	info!("listening on {}", listener.local_addr().unwrap());
+	axum::serve(listener, identity_server::router())
+		.await
+		.map_err(|e| e.into())
+}

apps/identity_server/src/uuid.rs

@@ -0,0 +1,104 @@
+//! Mockable UUID generation.
+
+use ::uuid::Uuid;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+/// Handles generation of UUIDs. This is used instead of the uuid crate directly,
+/// to better support deterministic UUID creation in tests.
+#[derive(Debug)]
+pub struct UuidProvider {
+	#[cfg(not(test))]
+	provider: ThreadLocalRng,
+	#[cfg(test)]
+	provider: Box<dyn UuidProviderT>,
+}
+
+impl UuidProvider {
+	#[allow(dead_code)]
+	pub fn new_thread_local() -> Self {
+		Self {
+			#[cfg(test)]
+			provider: Box::new(ThreadLocalRng),
+			#[cfg(not(test))]
+			provider: ThreadLocalRng,
+		}
+	}
+
+	/// Allows controlling the sequence of generated UUIDs. Only available in
+	/// `cfg(test)`.
+	#[allow(dead_code)]
+	#[cfg(test)]
+	pub fn new_from_sequence(uuids: Vec<Uuid>) -> Self {
+		Self {
+			provider: Box::new(TestSequence::new(uuids)),
+		}
+	}
+
+	#[inline]
+	pub fn next_v4(&self) -> Uuid {
+		self.provider.next_v4()
+	}
+}
+
+impl Default for UuidProvider {
+	fn default() -> Self {
+		Self::new_thread_local()
+	}
+}
+
+trait UuidProviderT: std::fmt::Debug + Send + Sync + 'static {
+	fn next_v4(&self) -> Uuid;
+}
+
+#[derive(Debug)]
+struct ThreadLocalRng;
+impl UuidProviderT for ThreadLocalRng {
+	fn next_v4(&self) -> Uuid {
+		Uuid::new_v4()
+	}
+}
+
+/// Provides UUIDs from a known sequence. Useful for tests.
+#[derive(Debug)]
+struct TestSequence {
+	uuids: Vec<Uuid>,
+	pos: AtomicUsize,
+}
+impl TestSequence {
+	/// # Panics
+	/// Panics if len of vec is 0
+	#[allow(dead_code)]
+	fn new(uuids: Vec<Uuid>) -> Self {
+		assert!(!uuids.is_empty());
+		Self {
+			uuids,
+			pos: AtomicUsize::new(0),
+		}
+	}
+}
+
+impl UuidProviderT for TestSequence {
+	fn next_v4(&self) -> Uuid {
+		let curr_pos = self.pos.fetch_add(1, Ordering::SeqCst) % self.uuids.len();
+		self.uuids[curr_pos]
+	}
+}
+
+fn _assert_bounds(p: UuidProvider) {
+	fn helper(_p: impl std::fmt::Debug + Send + Sync + 'static) {}
+	helper(p)
+}
+
+#[cfg(test)]
+mod test {
+	use super::*;
+
+	#[test]
+	fn test_sequence_order() {
+		let uuids: Vec<Uuid> = (0..4).map(|_| Uuid::new_v4()).collect();
+		let sequence = TestSequence::new(uuids.clone());
+		for uuid in uuids {
+			assert_eq!(uuid, sequence.next_v4());
+		}
+	}
+}