ptth/crates/ptth_relay/src/lib.rs

#![warn (clippy::pedantic)]

// I don't see the point of writing the type twice if I'm initializing a struct
// and the type is already in the struct definition.
#![allow (clippy::default_trait_access)]

// I'm not sure if I like this one
#![allow (clippy::enum_glob_use)]

// I don't see the point in documenting the errors outside of where the
// error type is defined.
#![allow (clippy::missing_errors_doc)]

// False positive on futures::select! macro
#![allow (clippy::mut_mut)]

use std::{
	borrow::Cow,
	net::SocketAddr,
	path::{Path, PathBuf},
	sync::Arc,
	time::Duration,
};

use chrono::{ 
	DateTime,
	SecondsFormat,
	Utc 
};
use dashmap::DashMap;
use handlebars::Handlebars;
use hyper::{
	Body, 
	Method,
	Request, 
	Response, 
	Server, 
	StatusCode,
};
use hyper::service::{make_service_fn, service_fn};
use serde::{
	Serialize,
};
use tokio::{
	sync::{
		oneshot,
	},
};

use ptth_core::{
	http_serde,
	prefix_match,
	prelude::*,
};

pub mod config;
pub mod errors;
pub mod git_version;
pub mod key_validity;
mod relay_state;

mod scraper_api;
mod server_endpoint;

pub use config::Config;
pub use errors::*;
pub use relay_state::RelayState;

use relay_state::*;

fn ok_reply <B: Into <Body>> (b: B)
-> Result <Response <Body>, http::Error>
{
	Response::builder ().status (StatusCode::OK).body (b.into ())
}

fn error_reply (status: StatusCode, b: &str)
-> Result <Response <Body>, http::Error>
{
	Response::builder ()
	.status (status)
	.header ("content-type", "text/plain")
	.body (format! ("{}\n", b).into ())
}

// Clients will come here to start requests, and always park for at least
// a short amount of time.

async fn handle_http_request (
	req: http::request::Parts,
	uri: String,
	state: Arc <RelayState>, 
	watcher_code: String
)
-> Result <Response <Body>, http::Error>
{
	{
		let config = state.config.read ().await;
		if ! config.servers.contains_key (&watcher_code) {
			return error_reply (StatusCode::NOT_FOUND, "Unknown server");
		}
	}
	
	let req = match http_serde::RequestParts::from_hyper (req.method, uri, req.headers) {
		Ok (x) => x,
		Err (_) => return error_reply (StatusCode::BAD_REQUEST, "Bad request"),
	};
	
	let (tx, rx) = oneshot::channel ();
	
	let req_id = ulid::Ulid::new ().to_string ();
	{
		let response_rendezvous = state.response_rendezvous.read ().await;
		response_rendezvous.insert (req_id.clone (), tx);
	}
	
	trace! ("Created request {}", req_id);
	
	{
		use RequestRendezvous::*;
		
		let mut request_rendezvous = state.request_rendezvous.lock ().await;
		
		let wrapped = http_serde::WrappedRequest {
			id: req_id.clone (),
			req,
		};
		
		let new_rendezvous = match request_rendezvous.remove (&watcher_code) {
			Some (ParkedClients (mut v)) => {
				debug! ("Parking request {} ({} already queued)", req_id, v.len ());
				v.push (wrapped);
				ParkedClients (v)
			},
			Some (ParkedServer (s)) => {
				// If sending to the server fails, queue it
				
				match s.send (Ok (wrapped)) {
					Ok (()) => {
						// TODO: This can actually still fail, if the server
						// disconnects right as we're sending this.
						// Then what?
						
						trace! (
							"Sending request {} directly to server {}", 
							req_id,
							watcher_code,
						);
						
						ParkedClients (vec! [])
					},
					Err (Ok (wrapped)) => {
						debug! ("Parking request {}", req_id);
						ParkedClients (vec! [wrapped])
					},
					Err (_) => unreachable! (),
				}
			},
			None => {
				debug! ("Parking request {}", req_id);
				ParkedClients (vec! [wrapped])
			},
		};
		
		request_rendezvous.insert (watcher_code, new_rendezvous);
	}
	
	let timeout = tokio::time::delay_for (std::time::Duration::from_secs (30));
	
	let received = tokio::select! {
		val = rx => val,
		() = timeout => {
			debug! ("Timed out request {}", req_id);
			return error_reply (StatusCode::GATEWAY_TIMEOUT, "Remote server never responded")
		},
    };
	
	// UKAUFFY4 (Receive half)
	match received {
		Ok (Ok ((parts, body))) => {
			let mut resp = Response::builder ()
			.status (hyper::StatusCode::from (parts.status_code));
			
			for (k, v) in parts.headers {
				resp = resp.header (&k, v);
			}
			
			debug! ("Unparked request {}", req_id);
			
			resp.body (body)
		},
		Ok (Err (ShuttingDownError::ShuttingDown)) => {
			error_reply (StatusCode::GATEWAY_TIMEOUT, "Relay shutting down")
		},
		Err (_) => {
			debug! ("Responder sender dropped for request {}", req_id);
			error_reply (StatusCode::GATEWAY_TIMEOUT, "Remote server timed out")
		},
	}
}

#[derive (Debug, PartialEq)]
enum LastSeen {
	Negative,
	Connected,
	Description (String),
}

// Mnemonic is "now - last_seen"

fn pretty_print_last_seen (
	now: DateTime <Utc>,
	last_seen: DateTime <Utc>
) -> LastSeen
{
	use LastSeen::*;
	
	let dur = now.signed_duration_since (last_seen);
	
	if dur < chrono::Duration::zero () {
		return Negative;
	}
	
	if dur.num_minutes () < 1 {
		return Connected;
	}
	
	if dur.num_hours () < 1 {
		return Description (format! ("{} m ago", dur.num_minutes ()));
	}
	
	if dur.num_days () < 1 {
		return Description (format! ("{} h ago", dur.num_hours ()));
	}
	
	Description (last_seen.to_rfc3339_opts (SecondsFormat::Secs, true))
}

#[derive (Serialize)]
struct ServerEntry <'a> {
	name: String,
	display_name: String,
	last_seen: Cow <'a, str>,
}

#[derive (Serialize)]
struct ServerListPage <'a> {
	dev_mode: bool,
	git_version: Option <String>,
	servers: Vec <ServerEntry <'a>>,
}

async fn handle_server_list_internal (state: &Arc <RelayState>)
-> ServerListPage <'static>
{
	use LastSeen::*;
	
	let dev_mode = {
		let guard = state.config.read ().await;
		guard.iso.dev_mode.is_some ()
	};
	let git_version = git_version::read_git_version ().await;
	
	let server_list = scraper_api::v1_server_list (&state).await;
	
	let now = Utc::now ();
	
	let servers = server_list.servers.into_iter ()
	.map (|x| {
		let last_seen = match x.last_seen {
			None => "Never".into (),
			Some (x) => match pretty_print_last_seen (now, x) {
				Negative => "Error (negative time)".into (),
				Connected => "Connected".into (),
				Description (s) => s.into (),
			},
		};
		
		ServerEntry {
			name: x.name,
			display_name: x.display_name,
			last_seen,
		}
	})
	.collect ();
	
	ServerListPage {
		dev_mode,
		git_version,
		servers,
	}
}

async fn handle_server_list (
	state: Arc <RelayState>,
	handlebars: Arc <Handlebars <'static>>
) -> Result <Response <Body>, RequestError>
{
	let page = handle_server_list_internal (&state).await;
	
	let s = handlebars.render ("relay_server_list", &page)?;
	Ok (ok_reply (s)?)
}

#[instrument (level = "trace", skip (req, state, handlebars))]
async fn handle_all (
	req: Request <Body>, 
	state: Arc <RelayState>,
	handlebars: Arc <Handlebars <'static>>
) 
-> Result <Response <Body>, RequestError>
{
	let path = req.uri ().path ().to_string ();
	//println! ("{}", path);
	
	debug! ("Request path: {}", path);
	
	if req.method () == Method::POST {
		// This is stuff the server can use. Clients can't
		// POST right now
		
		return if let Some (request_code) = prefix_match ("/7ZSFUKGV/http_response/", &path) {
			let request_code = request_code.into ();
			Ok (server_endpoint::handle_response (req, state, request_code).await?)
		}
		else {
			Ok (error_reply (StatusCode::BAD_REQUEST, "Can't POST this")?)
		};
	}
	
	if let Some (listen_code) = prefix_match ("/7ZSFUKGV/http_listen/", &path) {
		let api_key = req.headers ().get ("X-ApiKey");
		
		let api_key = match api_key {
			None => return Ok (error_reply (StatusCode::FORBIDDEN, "Can't run server without an API key")?),
			Some (x) => x,
		};
		server_endpoint::handle_listen (state, listen_code.into (), api_key.as_bytes ()).await
	}
	else if let Some (rest) = prefix_match ("/frontend/servers/", &path) {
		// DRY T4H76LB3
		
		if rest == "" {
			Ok (handle_server_list (state, handlebars).await?)
		}
		else if let Some (idx) = rest.find ('/') {
			let listen_code = String::from (&rest [0..idx]);
			let path = String::from (&rest [idx..]);
			let (parts, _) = req.into_parts ();
			
			Ok (handle_http_request (parts, path, state, listen_code).await?)
		}
		else {
			Ok (error_reply (StatusCode::BAD_REQUEST, "Bad URI format")?)
		}
	}
	else if path == "/" {
		let s = handlebars.render ("relay_root", &())?;
		Ok (ok_reply (s)?)
	}
	else if path == "/frontend/relay_up_check" {
		Ok (error_reply (StatusCode::OK, "Relay is up")?)
	}
	else if path == "/frontend/test_mysterious_error" {
		Err (RequestError::Mysterious)
	}
	else if let Some (rest) = prefix_match ("/scraper/", &path) {
		scraper_api::handle (req, state, rest).await
	}
	else {
		Ok (error_reply (StatusCode::OK, "Hi")?)
	}
}

pub fn load_templates (asset_root: &Path) 
-> Result <Handlebars <'static>, RelayError>
{
	let mut handlebars = Handlebars::new ();
	handlebars.set_strict_mode (true);
	
	let asset_root = asset_root.join ("handlebars/relay");
	
	for (k, v) in &[
		("relay_server_list", "relay_server_list.html"),
		("relay_root", "relay_root.html"),
	] {
		handlebars.register_template_file (k, &asset_root.join (v))?;
	}
	
	Ok (handlebars)
}

async fn reload_config (
	state: &Arc <RelayState>,
	config_reload_path: &Path
) -> Result <(), ConfigError> {
	let new_config = Config::from_file (config_reload_path).await?;
	let mut config = state.config.write ().await;
	
	trace! ("Reloading config");
	if config.servers.len () != new_config.servers.len () {
		debug! ("Loaded {} server configs", config.servers.len ());
	}
	if config.iso.enable_scraper_api != new_config.iso.enable_scraper_api {
		debug! ("enable_scraper_api: {}", config.iso.enable_scraper_api);
	}
	
	(*config) = new_config;
	
	if config.iso.dev_mode.is_some () {
		error! ("Dev mode is enabled! This might turn off some security features. If you see this in production, escalate it to someone!");
	}
	
	Ok (())
}

pub async fn run_relay (
	state: Arc <RelayState>,
	handlebars: Arc <Handlebars <'static>>,
	shutdown_oneshot: oneshot::Receiver <()>,
	config_reload_path: Option <PathBuf>
) 
-> Result <(), RelayError> 
{
	if let Some (config_reload_path) = config_reload_path {
		let state_2 = state.clone ();
		tokio::spawn (async move {
			let mut reload_interval = tokio::time::interval (Duration::from_secs (60));
			
			loop {
				reload_interval.tick ().await;
				reload_config (&state_2, &config_reload_path).await.ok ();
			}
		});
	}
	
	let make_svc = make_service_fn (|_conn| {
		let state = state.clone ();
		let handlebars = handlebars.clone ();
		
		async {
			Ok::<_, RequestError> (service_fn (move |req| {
				let state = state.clone ();
				let handlebars = handlebars.clone ();
				
				handle_all (req, state, handlebars)
			}))
		}
	});
	
	let addr = SocketAddr::from ((
		[0, 0, 0, 0],
		state.config.read ().await.port.unwrap_or (4000),
	));
	
	let server = Server::bind (&addr)
	.serve (make_svc);
	
	server.with_graceful_shutdown (async {
		use ShuttingDownError::ShuttingDown;
		
		shutdown_oneshot.await.ok ();
		
		state.shutdown_watch_tx.broadcast (true).expect ("Can't broadcast graceful shutdown");
		
		let mut response_rendezvous = state.response_rendezvous.write ().await;
		let mut swapped = DashMap::default ();
		
		std::mem::swap (&mut swapped, &mut response_rendezvous);
		
		for (_, sender) in swapped {
			sender.send (Err (ShuttingDown)).ok ();
		}
		
		let mut request_rendezvous = state.request_rendezvous.lock ().await;
		
		for (_, x) in request_rendezvous.drain () {
			use RequestRendezvous::*;
			
			match x {
				ParkedClients (_) => (),
				ParkedServer (sender) => drop (sender.send (Err (ShuttingDown))),
			}
		}
		
		debug! ("Performed all cleanup");
	}).await?;
	
	Ok (())
}

#[cfg (test)]
mod tests;