Per-host SSO: Node auth endpoints + Redis session (#57)

Adds the /__proxy_auth OIDC flow served on every proxied host:
- routes/host_auth.js: /start (PKCE+state, per-host redirect_uri), /callback
  (exchange, enforce the host allow-list via utils/host_sso.identityAllowed,
  mint session + set __proxy_sso cookie), /logout.
- models/sso_session.js: SsoSession (Redis-backed, TTL'd; read directly by the
  Lua gate) and HostSsoState (in-flight auth request).
- utils/oidc.js: per-host redirect_uri override on buildAuthUrl/exchangeCode.
- conf.hostSso (reuses conf.oidc). Allow-list logic unit-tested.

Enforcement (Lua gate + nginx location) lands next.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

nodejs/app.js

@@ -60,10 +60,15 @@ app.use(express.json());
 app.set('views', path.join(__dirname, 'views'));
 app.set('view engine', 'ejs');
 
+// Per-host SSO endpoints. nginx routes /__proxy_auth/* on every proxied host to
+// the app (see ops/nginx_conf/proxy.conf); these run the OIDC flow and set the
+// per-host session cookie. Mounted before the page router.
+app.use('/__proxy_auth', require('./routes/host_auth'));
+
 // Routes for front end content.
 app.use('/', require('./routes/render'));
 
-// Routes for API 
+// Routes for API
 app.use('/api', require('./routes/api'));
 
 // Catch 404 and forward to error handler. If none of the above routes are

nodejs/conf/base.js

@@ -77,4 +77,13 @@ module.exports = {
 			'https://ifconfig.me/ip',
 		],
 	},
+
+	// Per-host SSO (#57). Reuses conf.oidc for the identity provider. Sessions
+	// are Redis-backed and read directly by OpenResty; the cookie only carries a
+	// random session id.
+	hostSso:{
+		enabled: true,
+		sessionTtl: 28800,          // 8 hours, in seconds
+		cookieName: '__proxy_sso',
+	},
 };

nodejs/models/index.js

@@ -14,3 +14,4 @@ require('./user');
 require('./local_group');
 require('./permission');
 require('./oidc_state');
+require('./sso_session');

nodejs/models/sso_session.js

@@ -0,0 +1,52 @@
+'use strict';
+
+const Table = require('.');
+const conf = require('@simpleworkjs/conf');
+
+/**
+ * Per-host SSO models (#57).
+ *
+ * HostSsoState — short-lived, in-flight OIDC authorization request for a
+ * protected host (like OidcState, but carries the target host + post-login
+ * redirect). Auto-expires via TTL.
+ *
+ * SsoSession — an established session after a successful, authorized login.
+ * Keyed by a random session id stored in the browser's `__proxy_sso` cookie.
+ * OpenResty (ops/nginx_conf/hostfeatures.lua) reads `proxy_SsoSession_<sid>`
+ * straight from Redis to gate requests; the allow-list was already enforced at
+ * callback time (utils/host_sso.js), so the Lua side only checks that a session
+ * exists and belongs to this host. Auto-expires via TTL.
+ */
+
+const SESSION_TTL = (conf.hostSso && conf.hostSso.sessionTtl) || 28800; // 8h
+
+class HostSsoState extends Table{
+	static _key = 'state';
+	static _ttl = 300; // 5 minutes bounds the auth round-trip / replay
+	static _keyMap = {
+		'created_on': {default: function(){return (new Date).getTime()}},
+		'state': {isRequired: true, type: 'string', min: 8, max: 500},
+		'codeVerifier': {isRequired: true, type: 'string', min: 8, max: 500},
+		'host': {isRequired: true, type: 'string', min: 1, max: 500},
+		'rd': {default: '/', isRequired: false, type: 'string'},
+	}
+}
+HostSsoState.register();
+
+class SsoSession extends Table{
+	static _key = 'sid';
+	static _ttl = SESSION_TTL;
+	static _keyMap = {
+		'created_on': {default: function(){return (new Date).getTime()}},
+		'sid': {isRequired: true, type: 'string', min: 16, max: 500},
+		'host': {isRequired: true, type: 'string', min: 1, max: 500},
+		'sub': {isRequired: true, type: 'string', min: 1, max: 500},
+		'email': {default: '', isRequired: false, type: 'string'},
+		'groups': {default: function(){return []}, isRequired: false, type: 'object'},
+	}
+
+	static ttl(){ return SESSION_TTL; }
+}
+SsoSession.register();
+
+module.exports = {HostSsoState, SsoSession};

nodejs/package.json

@@ -11,10 +11,10 @@
   "scripts": {
     "start": "node ./bin/www",
     "dev": "npx nodemon --ignore public/ ./bin/www",
-    "test": "node --test test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/unix_socket.test.js test/integration/dns_provider.test.js",
+    "test": "node --test test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/host_sso.test.js test/unit/unix_socket.test.js test/integration/dns_provider.test.js",
-    "test:unit": "node --test test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/unix_socket.test.js",
+    "test:unit": "node --test test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/host_sso.test.js test/unit/unix_socket.test.js",
     "test:integration": "node --test test/integration/dns_provider.test.js",
-    "test:watch": "node --test --watch test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/unix_socket.test.js test/integration/dns_provider.test.js"
+    "test:watch": "node --test --watch test/unit/callback_queue.test.js test/unit/host_lookup.test.js test/unit/wildcard_matchany.test.js test/unit/roles.test.js test/unit/oidc.test.js test/unit/safe_redirect.test.js test/unit/host_features.test.js test/unit/dynamic_record.test.js test/unit/hostname_validate.test.js test/unit/password_policy.test.js test/unit/basicauth.test.js test/unit/host_sso.test.js test/unit/unix_socket.test.js test/integration/dns_provider.test.js"
   },
   "engines": {
     "node": ">=18.0.0"

nodejs/routes/host_auth.js

@@ -0,0 +1,145 @@
+'use strict';
+
+/**
+ * Per-host SSO endpoints (#57), served under /__proxy_auth on EVERY proxied host
+ * (nginx routes that path here; see ops/nginx_conf/proxy.conf). These run the
+ * OIDC authorization-code flow (reusing utils/oidc.js and conf.oidc) and, on a
+ * successful + authorized login, mint a Redis-backed SsoSession and set the
+ * `__proxy_sso` cookie for the host. OpenResty then gates the host on that
+ * session (ops/nginx_conf/hostfeatures.lua).
+ *
+ * Callback style: per-host (option A) — redirect_uri is
+ * https://<host>/__proxy_auth/callback, so each protected host's callback must
+ * be an allowed redirect URI at the IdP (a wildcard redirect URI covers all).
+ */
+
+const router = require('express').Router();
+const conf = require('@simpleworkjs/conf');
+const oidc = require('../utils/oidc');
+const {Host} = require('../models').models;
+const {HostSsoState, SsoSession} = require('../models/sso_session');
+const {identityAllowed} = require('../utils/host_sso');
+
+const COOKIE = (conf.hostSso && conf.hostSso.cookieName) || '__proxy_sso';
+
+// Minimal HTML notice page (these endpoints are hit by browsers, not the API).
+function page(message){
+	return `<!doctype html><html><head><meta charset="utf-8"><title>Sign in</title>`
+		+ `<meta name="viewport" content="width=device-width, initial-scale=1">`
+		+ `<style>body{font-family:system-ui,sans-serif;max-width:32rem;margin:4rem auto;padding:0 1rem;color:#222}</style>`
+		+ `</head><body><p>${String(message).replace(/[<>&]/g, c => ({'<':'&lt;','>':'&gt;','&':'&amp;'}[c]))}</p></body></html>`;
+}
+
+// This host's own callback URL — must match between authorize and token steps.
+function callbackUri(req){
+	return `${req.protocol}://${req.get('host')}/__proxy_auth/callback`;
+}
+
+// Constrain the post-login redirect to this same host (no open redirect). `rd`
+// may be a bare path or a full same-host URL.
+function safeRd(req, rd){
+	try{
+		if(!rd) return '/';
+		if(rd.charAt(0) === '/' && rd.charAt(1) !== '/') return rd;
+		let u = new URL(rd);
+		if(u.host === req.get('host')) return u.pathname + u.search;
+	}catch(error){ /* fall through */ }
+	return '/';
+}
+
+function readCookie(req, name){
+	for(let part of (req.headers.cookie || '').split(';')){
+		let idx = part.indexOf('=');
+		if(idx === -1) continue;
+		if(part.slice(0, idx).trim() === name) return decodeURIComponent(part.slice(idx + 1).trim());
+	}
+	return null;
+}
+
+// Resolve the effective Host record (exact, else via the wildcard lookup tree)
+// so we can read its SSO allow-lists.
+async function resolveHost(hostname){
+	try{ return await Host.get(hostname); }catch(error){ /* try wildcard */ }
+	try{ return Host.lookUp(hostname) || null; }catch(error){ return null; }
+}
+
+// Begin login: create PKCE/state, remember the target host + return path, and
+// redirect the browser to the IdP.
+router.get('/start', async function(req, res, next){
+	try{
+		if(!conf.oidc || !conf.oidc.enabled){
+			return res.status(503).send(page('SSO is not configured on this proxy.'));
+		}
+		let hostname = req.hostname;
+		let hostRec = await resolveHost(hostname);
+		if(!hostRec || !hostRec.sso_enabled){
+			return res.status(404).send(page('SSO is not enabled for this host.'));
+		}
+
+		let {state, codeVerifier, codeChallenge} = oidc.createAuthRequest();
+		await HostSsoState.create({state, codeVerifier, host: hostname, rd: safeRd(req, req.query.rd)});
+
+		return res.redirect(oidc.buildAuthUrl(state, codeChallenge, callbackUri(req)));
+	}catch(error){
+		return next(error);
+	}
+});
+
+// OIDC redirect target: validate state, exchange the code, enforce the host's
+// allow-list, then establish the session and return the user to where they were.
+router.get('/callback', async function(req, res, next){
+	try{
+		let {code, state} = req.query;
+		if(!code || !state) return res.status(400).send(page('Missing authorization code.'));
+
+		let st = await HostSsoState.get(state).catch(() => null);
+		if(!st) return res.status(400).send(page('Your login session expired. Please try again.'));
+		await st.remove().catch(() => {});   // one-time use
+
+		let hostname = req.hostname;
+		if(st.host !== hostname) return res.status(400).send(page('Login host mismatch.'));
+
+		let tokens = await oidc.exchangeCode(code, st.codeVerifier, callbackUri(req));
+		let claims = await oidc.fetchUserInfo(tokens.access_token);
+		let identity = oidc.claimsToIdentity(claims);
+		let email = claims.email || '';
+
+		let hostRec = await resolveHost(hostname);
+		let allowUsers = (hostRec && hostRec.sso_allow_users) || [];
+		let allowGroups = (hostRec && hostRec.sso_allow_groups) || [];
+
+		if(!identityAllowed({username: identity.username, email, groups: identity.groups}, allowUsers, allowGroups)){
+			return res.status(403).send(page(`You are not authorized to access ${hostname}.`));
+		}
+
+		let sid = oidc.randomToken(32);
+		await SsoSession.create({sid, host: hostname, sub: identity.username, email, groups: identity.groups || []});
+
+		res.cookie(COOKIE, sid, {
+			httpOnly: true,
+			secure: req.protocol === 'https',
+			sameSite: 'lax',
+			path: '/',
+			maxAge: SsoSession.ttl() * 1000,
+		});
+		return res.redirect(safeRd(req, st.rd));
+	}catch(error){
+		return next(error);
+	}
+});
+
+// End the session for this host.
+router.get('/logout', async function(req, res, next){
+	try{
+		let sid = readCookie(req, COOKIE);
+		if(sid){
+			try{ let s = await SsoSession.get(sid); await s.remove(); }catch(error){ /* gone */ }
+		}
+		res.clearCookie(COOKIE, {path: '/'});
+		return res.redirect(safeRd(req, req.query.rd));
+	}catch(error){
+		return next(error);
+	}
+});
+
+module.exports = router;

nodejs/test/unit/host_sso.test.js

@@ -0,0 +1,42 @@
+'use strict';
+
+const {describe, test} = require('node:test');
+const assert = require('node:assert');
+
+const {identityAllowed} = require('../../utils/host_sso');
+
+describe('identityAllowed (per-host SSO authorization)', () => {
+	const id = {username: 'alice', email: 'alice@x.com', groups: ['dns-team', 'staff']};
+
+	test('empty allow-lists allow any authenticated user', () => {
+		assert.strictEqual(identityAllowed(id, [], []), true);
+		assert.strictEqual(identityAllowed(id, undefined, undefined), true);
+	});
+
+	test('allows by username', () => {
+		assert.strictEqual(identityAllowed(id, ['bob', 'alice'], []), true);
+	});
+
+	test('allows by email', () => {
+		assert.strictEqual(identityAllowed(id, ['alice@x.com'], []), true);
+	});
+
+	test('allows by group membership', () => {
+		assert.strictEqual(identityAllowed(id, [], ['dns-team']), true);
+	});
+
+	test('denies when neither user nor group matches a non-empty list', () => {
+		assert.strictEqual(identityAllowed(id, ['bob'], ['admins']), false);
+	});
+
+	test('is case-insensitive', () => {
+		assert.strictEqual(identityAllowed(id, ['ALICE'], []), true);
+		assert.strictEqual(identityAllowed(id, [], ['DNS-Team']), true);
+		assert.strictEqual(identityAllowed({username: 'A', email: 'A@X.com'}, ['a@x.com'], []), true);
+	});
+
+	test('handles a missing/empty identity gracefully', () => {
+		assert.strictEqual(identityAllowed({}, ['bob'], ['admins']), false);
+		assert.strictEqual(identityAllowed({}, [], []), true);
+	});
+});

nodejs/utils/host_sso.js

@@ -0,0 +1,35 @@
+'use strict';
+
+/**
+ * Pure authorization check for per-host SSO (#57).
+ *
+ * After the OIDC dance, the callback decides whether the authenticated identity
+ * may access the host, based on the host's allow-lists. Enforcing here (at
+ * session creation) keeps the OpenResty side simple — the Lua gate only has to
+ * confirm a valid session exists for the host.
+ *
+ * Semantics: empty allow-lists mean "any authenticated user". Otherwise the
+ * identity is allowed if its username OR email is in sso_allow_users, or any of
+ * its groups is in sso_allow_groups. All comparisons are case-insensitive.
+ */
+function identityAllowed(identity, allowUsers, allowGroups){
+	identity = identity || {};
+	allowUsers = Array.isArray(allowUsers) ? allowUsers : [];
+	allowGroups = Array.isArray(allowGroups) ? allowGroups : [];
+
+	if(allowUsers.length === 0 && allowGroups.length === 0) return true;
+
+	let lc = s => String(s).trim().toLowerCase();
+
+	let ids = [identity.username, identity.email].filter(Boolean).map(lc);
+	let users = allowUsers.map(lc);
+	if(ids.some(id => users.includes(id))) return true;
+
+	let groups = (Array.isArray(identity.groups) ? identity.groups : []).map(lc);
+	let allow = allowGroups.map(lc);
+	if(groups.some(g => allow.includes(g))) return true;
+
+	return false;
+}
+
+module.exports = {identityAllowed};

nodejs/utils/oidc.js

@@ -36,13 +36,14 @@ function createAuthRequest(){
 	return {state, codeVerifier, codeChallenge};
 }
 
-// Build the SSO authorize URL the browser is redirected to.
+// Build the SSO authorize URL the browser is redirected to. `redirectUri`
-function buildAuthUrl(state, codeChallenge){
+// overrides conf.oidc.redirectUri (per-host SSO uses a per-host callback).
+function buildAuthUrl(state, codeChallenge, redirectUri){
 	let o = conf.oidc;
 	let params = new URLSearchParams({
 		response_type: 'code',
 		client_id: o.clientId,
-		redirect_uri: o.redirectUri,
+		redirect_uri: redirectUri || o.redirectUri,
 		scope: (o.scopes || ['openid', 'profile', 'email', 'groups']).join(' '),
 		state,
 		code_challenge: codeChallenge,
@@ -51,13 +52,14 @@ function buildAuthUrl(state, codeChallenge){
 	return `${o.authorizationEndpoint}?${params.toString()}`;
 }
 
-// Exchange an authorization code for tokens at the token endpoint.
+// Exchange an authorization code for tokens at the token endpoint. `redirectUri`
-async function exchangeCode(code, codeVerifier){
+// must match the one used in buildAuthUrl (per-host for per-host SSO).
+async function exchangeCode(code, codeVerifier, redirectUri){
 	let o = conf.oidc;
 	let body = new URLSearchParams({
 		grant_type: 'authorization_code',
 		code,
-		redirect_uri: o.redirectUri,
+		redirect_uri: redirectUri || o.redirectUri,
 		client_id: o.clientId,
 		client_secret: o.clientSecret,
 		code_verifier: codeVerifier,