[auth] discord login

apps/auth/src/auth.app.ts

@@ -37,7 +37,12 @@ import {
 	withNotFound,
 	withOnError,
 } from '@repo/hono-helpers'
-import { generateToken, TOKEN_TTL_SECONDS, validateAndGetAccountId } from '@repo/jwt'
+import {
+	generateToken,
+	TOKEN_TTL_SECONDS,
+	validateAndGetAccountId,
+	validateIdentityAssertion,
+} from '@repo/jwt'
 
 // The account-wide ban lives on a `report` row, whose table the api worker owns; its db
 // module is plain D1 queries with no runtime deps, so it imports cleanly here.
@@ -67,6 +72,7 @@ import {
 import {
 	countAccountsForPlatformIdentity,
 	getLinksForAccount,
+	getLinksForIdentity,
 	getLinksForPlatformId,
 	getLinksForPlatformIdentity,
 	isPlatformIdentityLinked,
@@ -108,6 +114,21 @@ const TOKEN_SCOPE =
  */
 const BLOCKED_DESCRIPTION = 'this device or network is blocked'
 
+/**
+ * The website's "Sign in with Discord". `www` completes the Discord OAuth2 exchange (it
+ * alone holds the client secret), then posts an `assertion` — an HS256 token signed with
+ * the shared JWT_SECRET naming the platform identity it just proved (see `@repo/jwt`'s
+ * `generateIdentityAssertion`). This grant trusts the assertion the way `cached_login`
+ * trusts a Steam ticket, resolves it through the link table, and issues the ordinary
+ * session. No account linked to the identity means a NEW one is made and linked, so a
+ * Discord account is a way to join without Steam or Meta; the player then sets a password
+ * on the website and signs in with it anywhere — a sideloaded Quest included.
+ */
+const IDENTITY_ASSERTION_GRANT = 'identity_assertion'
+
+/** What the grant answers when one identity opens several accounts; never true today. */
+const AMBIGUOUS_IDENTITY_DESCRIPTION = 'platform identity is linked to more than one account'
+
 /**
  * The platform id a SIDELOADED Oculus APK reports. It is not an identity: a sideloaded
  * build has no Meta SDK to ask, so it has nothing real to report — and every sideloaded
@@ -443,7 +464,13 @@ function oauthError(
  * already been authenticated — here, because the player approved a Studio code
  * on the website. Studio reads `expires_in` as seconds (`TimeSpan.FromSeconds`).
  */
-async function issueSession(c: Context<App>, accountId: number, grantType: string) {
+async function issueSession(
+	c: Context<App>,
+	accountId: number,
+	grantType: string,
+	/** Extra top-level fields on the token body — `created: true` on an identity signup. */
+	extra: Record<string, unknown> = {}
+) {
 	const clientIp = c.req.header('cf-connecting-ip') ?? ''
 	const ban = await resolveBan(c.env.DB, accountId, {
 		identity: { ip: clientIp },
@@ -516,9 +543,109 @@ async function issueSession(c: Context<App>, accountId: number, grantType: strin
 		refresh_token: refreshToken,
 		scope: TOKEN_SCOPE,
 		key: '8oQ+e+WQaOBPbEcakhqs3dwZZdOmmyDUmJSD9u4AHMY=',
+		...extra,
 	})
 }
 
+/**
+ * The `identity_assertion` grant: sign into — or create — the account behind a platform
+ * identity another worker has verified and signed for. See IDENTITY_ASSERTION_GRANT.
+ *
+ * Handled before the password fallback and outside the version/rollout gates, like the
+ * Studio device grant: nothing here posts a `ver`, and the credential is the assertion
+ * alone. The assertion names an IDENTITY, not an account; which account that is (or that
+ * there is none yet) is decided here, from the same table `cached_login` reads, so the
+ * website can never choose an account id for itself.
+ *
+ * Creating an account when the identity opens none is deliberate — it is the Discord
+ * sign-up — and takes the same guards `create_account` does for a verified platform
+ * identity: the evasion arms (a banned player's next move is a new account), the per-IP
+ * cap (`www` forwards the browser's real address over the service binding) and the
+ * per-identity cap. NOT the PASSWORD_SIGNUP switch: that exists because a password account
+ * has no identity but its address, and this one has a Discord user Discord itself vouched
+ * for, one account per user. The new account carries no `platform`/`platformId` on its
+ * blob — only the link — so its DTO and token read like a password account's and the
+ * Discord snowflake stays off the wire, exactly as the benefits claim keeps it.
+ */
+async function identityAssertionGrant(c: Context<App>, body: Record<string, unknown>) {
+	const assertion = typeof body.assertion === 'string' ? body.assertion : ''
+	const jwtSecret = await c.env.JWT_SECRET.get()
+	if (jwtSecret === '') {
+		logger.error('refusing an identity assertion: JWT_SECRET is empty')
+		return oauthError(c, 'server_error', 'token signing is not configured', 500)
+	}
+	const identity = assertion ? await validateIdentityAssertion(assertion, jwtSecret) : null
+	if (identity === null) {
+		return oauthError(c, 'invalid_grant', 'invalid or expired identity assertion')
+	}
+
+	const links = await getLinksForIdentity(c.env.DB, identity.platform, identity.platformId)
+	if (links.length > 1) {
+		// The benefits claim keeps a Discord identity on one account, so this is a data
+		// problem rather than a player's choice to make; refused rather than guessed.
+		logger.error('identity assertion names an identity linked to several accounts', {
+			platform: identity.platform,
+			accountIds: links.map((l) => l.accountId),
+		})
+		return oauthError(c, 'invalid_grant', AMBIGUOUS_IDENTITY_DESCRIPTION)
+	}
+	if (links.length === 1) {
+		return issueSession(c, links[0].accountId, IDENTITY_ASSERTION_GRANT)
+	}
+
+	// Nobody yet: the sign-up. Everything below mirrors create_account's platform path.
+	const clientIp = c.req.header('cf-connecting-ip') ?? ''
+	const blocked = await resolveBan(c.env.DB, null, {
+		identity: { ip: clientIp, platform: identity.platform, platformId: identity.platformId },
+		arms: banEvasionMatch(c.env.BAN_EVASION_MATCH),
+	})
+	if (blocked) {
+		logger.info('identity signup refused: player banned', {
+			via: blocked.via,
+			bannedAccountId: blocked.bannedAccountId,
+			ip: clientIp,
+			platform: identity.platform,
+		})
+		return oauthError(c, 'invalid_grant', BLOCKED_DESCRIPTION)
+	}
+	const maxPerPlatformId = intVar(
+		c.env.MAX_ACCOUNTS_PER_PLATFORM_ID,
+		DEFAULT_MAX_ACCOUNTS_PER_PLATFORM_ID
+	)
+	if (
+		maxPerPlatformId > 0 &&
+		(await countAccountsForPlatformIdentity(c.env.DB, identity.platform, identity.platformId)) >=
+			maxPerPlatformId
+	) {
+		logger.info('identity signup rejected: platform account limit', { platform: identity.platform })
+		return oauthError(c, 'invalid_grant', 'account limit reached for this platform account')
+	}
+	const maxPerIp = intVar(c.env.MAX_ACCOUNTS_PER_IP, DEFAULT_MAX_ACCOUNTS_PER_IP)
+	if (
+		maxPerIp > 0 &&
+		clientIp !== '' &&
+		(await countAccountsBySignupIp(c.env.DB, clientIp)) >= maxPerIp
+	) {
+		logger.info('identity signup rejected: per-IP account limit', { ip: clientIp })
+		return oauthError(c, 'invalid_grant', 'too many accounts created from this network')
+	}
+
+	const account = await createAccount(c.env.DB, {
+		platforms: 0,
+		lastLoginTime: new Date().toISOString(),
+		signupIp: clientIp || undefined,
+		lastLoginIp: clientIp || undefined,
+	})
+	await linkPlatformIdentity(c.env.DB, account.accountId, identity.platform, identity.platformId)
+	await placeNewPlayerInOrientation(c.env, account.accountId, 0)
+	logger.info('created an account from an identity assertion', {
+		accountId: account.accountId,
+		platform: identity.platform,
+		ip: clientIp,
+	})
+	return issueSession(c, account.accountId, IDENTITY_ASSERTION_GRANT, { created: true })
+}
+
 async function decideDeviceCode(c: Context<App>, decide: typeof approveDeviceGrant) {
 	const id = await authedId(c)
 	if (id === null) return c.body(null, 401)
@@ -922,7 +1049,7 @@ const app = new Hono<App>()
 			tags: ['Token'],
 			summary: 'OAuth token endpoint — issues a JWT',
 			description: [
-				'Issues an access token (plus a single-use refresh token) for one of four grants,',
+				'Issues an access token (plus a single-use refresh token) for one of six grants,',
 				'selected by `grant_type`. Every grant returns the same body on success.',
 				'',
 				'**`create_account`** — mints a new account with an auto-assigned random username',
@@ -945,6 +1072,17 @@ const app = new Hono<App>()
 				'**`refresh_token`** — redeems a stored single-use refresh token, rotating it. The',
 				'platform and platform id come from what was stored at issue time, not the body.',
 				'',
+				'**`identity_assertion`** — the website’s "Sign in with Discord". `www` completes the',
+				'Discord OAuth2 code exchange (it alone holds the client secret) and posts an',
+				'`assertion`: an HS256 token signed with the shared JWT_SECRET naming the platform',
+				'(`101`) and platform id it proved, good for a minute. The identity is resolved through',
+				'the same link table as `cached_login`: one linked account is signed into; none means a',
+				'NEW account is created and linked (the body then carries `created: true`), under the',
+				'evasion check and the per-IP and per-identity signup caps but NOT the PASSWORD_SIGNUP',
+				'switch — the Discord user is the identity a password account lacks. The new account',
+				'has no password until its owner sets one on the website; with one, it signs in',
+				'anywhere the `password` grant does. Several linked accounts is refused.',
+				'',
 				'**`password`** (the fallback for any unrecognised or absent `grant_type`) —',
 				'identifies the account by `username` or numeric `account_id` and requires the',
 				'matching `password`. An account with no stored hash cannot be logged into at all,',
@@ -1072,6 +1210,9 @@ const app = new Hono<App>()
 				}
 				return issueSession(c, polled.accountId, DEVICE_CODE_GRANT)
 			}
+			// The website's Discord sign-in, likewise before the fallback — and before the
+			// version gates, which it never posts a `ver` for. See identityAssertionGrant.
+			if (grantType === IDENTITY_ASSERTION_GRANT) return identityAssertionGrant(c, body)
 			// `platform`/`platform_id` come from the body for a fresh login; a refresh
 			// grant overrides them below with what was stored when the token was issued.
 			let platformId = typeof body.platform_id === 'string' ? body.platform_id : ''

apps/auth/src/openapi.ts

@@ -143,10 +143,12 @@ export const TokenRequest = z.object({
 			'refresh_token',
 			'password',
 			'urn:ietf:params:oauth:grant-type:device_code',
+			'identity_assertion',
 		])
 		.describe(
 			'Anything unrecognised (including absent) is treated as a password grant, except the ' +
-				'Studio device-code URN, which polls a code from POST /connect/deviceauthorization'
+				'Studio device-code URN, which polls a code from POST /connect/deviceauthorization, ' +
+				'and identity_assertion, the website’s Discord sign-in'
 		),
 	account_id: z.string().optional().describe('Numeric account id, as a string'),
 	username: z
@@ -183,6 +185,13 @@ export const TokenRequest = z.object({
 		.string()
 		.optional()
 		.describe('Studio device-code grant: the device_code from /connect/deviceauthorization'),
+	assertion: z
+		.string()
+		.optional()
+		.describe(
+			'identity_assertion grant: the HS256 assertion `www` minted with the shared JWT_SECRET ' +
+				'after completing a Discord OAuth2 exchange, naming the platform and platform_id it proved'
+		),
 	device_id: z
 		.string()
 		.optional()

apps/auth/src/platform-db.ts

@@ -314,6 +314,87 @@ export async function getLinksForPlatformId(
 	return results.map(toLink)
 }
 
+/**
+ * Every account a platform identity is linked to, on ANY platform — including the ones
+ * {@link CACHED_LOGIN_PLATFORMS} keeps out of the picker.
+ *
+ * This is the unfiltered twin of {@link getLinksForPlatformIdentity}, and it must stay off
+ * every public route: the filter there exists so nobody can learn which account a Discord
+ * user owns by naming their snowflake. The one caller is `auth`'s `identity_assertion`
+ * grant, where the identity being asked about has just been PROVEN by the worker that
+ * minted the assertion — the website's Discord sign-in — so the answer goes to the person
+ * it is about and nobody else. Add a caller only under the same condition.
+ */
+export async function getLinksForIdentity(
+	db: D1Database,
+	platform: number,
+	platformId: string
+): Promise<PlatformLink[]> {
+	if (platformId === '') return []
+	const { results } = await db
+		.prepare(
+			`${SELECT_LINK} WHERE platform = ?1 AND platform_id = ?2 ORDER BY linked_at, account_id`
+		)
+		.bind(platform, platformId)
+		.all<LinkRow>()
+	return results.map(toLink)
+}
+
+/**
+ * Whether any of the account's links on `platform` has roles RECORDED — a non-null `role`
+ * column, which only the website's benefits claim (and the sweep behind it) ever writes.
+ *
+ * This is what "has this account claimed its Discord benefits" means now that a Discord
+ * link can exist WITHOUT a claim: signing in with Discord (`auth`'s `identity_assertion`
+ * grant) links the identity on a brand-new account with `role` NULL. The claim's one-time
+ * gift and its page both ask this rather than "is there a link", so a player who made
+ * their account from Discord is still owed, and still shown, their first claim.
+ * An EMPTY role list counts as recorded: that is a claim that found no roles.
+ */
+export async function hasRecordedRoles(
+	db: D1Database,
+	accountId: number,
+	platform: number
+): Promise<boolean> {
+	const row = await db
+		.prepare(
+			`SELECT 1 AS ok FROM platform_account
+			 WHERE account_id = ?1 AND platform = ?2 AND role IS NOT NULL LIMIT 1`
+		)
+		.bind(accountId, platform)
+		.first<{ ok: number }>()
+	return row !== null
+}
+
+/**
+ * Record roles on an existing link that has NONE yet (`role` NULL), atomically. True when
+ * this call was the one that did it; false when the link is missing or already carries a
+ * role list — in which case nothing is written, and {@link linkPlatformIdentity}'s refresh
+ * is the caller's next step.
+ *
+ * The one-shot flip is the point: the benefits claim pays its first-claim gift on the
+ * INSERT of a fresh link, which two racing claims cannot both win. A link made by a Discord
+ * sign-in is already inserted by the time the claim comes, so this gives the claim the
+ * same single-winner write on the roles column instead.
+ */
+export async function recordFirstRoles(
+	db: D1Database,
+	accountId: number,
+	platform: number,
+	platformId: string,
+	roles: readonly string[]
+): Promise<boolean> {
+	if (platformId === '') return false
+	const res = await db
+		.prepare(
+			`UPDATE platform_account SET role = ?4
+			 WHERE account_id = ?1 AND platform = ?2 AND platform_id = ?3 AND role IS NULL`
+		)
+		.bind(accountId, platform, platformId, JSON.stringify([...roles]))
+		.run()
+	return res.meta.changes > 0
+}
+
 /** Every platform identity linked to an account (a player's PC and headset, say). */
 export async function getLinksForAccount(
 	db: D1Database,

apps/auth/src/test/integration/api.test.ts

@@ -16,7 +16,12 @@ import {
 	SUBROOM_SCHEMA_DDL,
 	updateAccount,
 } from '@repo/domain'
-import { TOKEN_TTL_SECONDS } from '@repo/jwt'
+import {
+	generateIdentityAssertion,
+	generateToken,
+	TOKEN_TTL_SECONDS,
+	validateIdentityAssertion,
+} from '@repo/jwt'
 
 import {
 	banFromReport,
@@ -2579,3 +2584,145 @@ describe('staff login audit', () => {
 		expect(await staffLogins(9605)).toHaveLength(1)
 	})
 })
+
+// The website's "Sign in with Discord". `www` proves the Discord user (it holds the client
+// secret) and posts an identity ASSERTION signed with the shared JWT_SECRET; this grant
+// resolves it through the link table like a cached_login, or makes the account when there
+// is none. Everything here mints the assertion the way www does, with the test key.
+describe('identity_assertion grant', () => {
+	const SIGNING_KEY = 'test-signing-key'
+	const assertionFor = (platformId: string, platform = PlatformType.Discord) =>
+		generateIdentityAssertion({ platform, platformId }, SIGNING_KEY)
+	const redeem = async (assertion: string, ip?: string) =>
+		postToken(`grant_type=identity_assertion&assertion=${encodeURIComponent(assertion)}`, ip)
+
+	test('an assertion round-trips, and nothing else passes as one', async () => {
+		const assertion = await assertionFor('700000000000000001')
+		await expect(validateIdentityAssertion(assertion, SIGNING_KEY)).resolves.toEqual({
+			platform: PlatformType.Discord,
+			platformId: '700000000000000001',
+		})
+		// A different key, and an access token signed with the RIGHT key: both refused. The
+		// second is the one that matters — the same secret signs sessions, so the audience is
+		// what keeps a stolen token from being replayed as proof of a platform identity.
+		await expect(validateIdentityAssertion(assertion, 'another-key')).resolves.toBeNull()
+		const session = await generateToken('42', '', 4, SIGNING_KEY)
+		await expect(validateIdentityAssertion(session, SIGNING_KEY)).resolves.toBeNull()
+		// And the other direction: an assertion carries no `sub`, so it is no session.
+		const res = await exports.default.fetch(`${ORIGIN}/connect/device/approve`, {
+			method: 'POST',
+			headers: {
+				'Content-Type': 'application/x-www-form-urlencoded',
+				Authorization: `Bearer ${assertion}`,
+			},
+			body: 'user_code=ABCDEFGH',
+		})
+		expect(res.status).toBe(401)
+	})
+
+	test('signs into the one account the identity is linked to', async () => {
+		await seedAccount(9400, 'DiscordLinked')
+		// Linked the way the benefits claim links: with roles recorded.
+		await linkPlatformIdentity(env.DB, 9400, PlatformType.Discord, '700000000000009400', [])
+		const res = await redeem(await assertionFor('700000000000009400'))
+		expect(res.status).toBe(200)
+		expect(decodePayload(res.json.access_token as string).sub).toBe('9400')
+		expect(res.json).not.toHaveProperty('created')
+		expect(typeof res.json.refresh_token).toBe('string')
+	})
+
+	test('refuses a missing, forged or replayed-session assertion', async () => {
+		expect((await postToken('grant_type=identity_assertion')).status).toBe(400)
+		const forged = await generateIdentityAssertion(
+			{ platform: PlatformType.Discord, platformId: '700000000000009400' },
+			'not-the-key'
+		)
+		const res = await redeem(forged)
+		expect(res.status).toBe(400)
+		expect(res.json.error_description).toBe('invalid or expired identity assertion')
+		// An access token for the linked account, presented as the assertion.
+		const session = await generateToken('9400', '', 4, SIGNING_KEY)
+		expect((await redeem(session)).status).toBe(400)
+	})
+
+	test('creates and links an account when the identity opens none, once', async () => {
+		const discordId = '700000000000009401'
+		const first = await redeem(await assertionFor(discordId))
+		expect(first.status).toBe(200)
+		expect(first.json.created).toBe(true)
+		const accountId = Number(decodePayload(first.json.access_token as string).sub)
+		expect(accountId).toBeGreaterThan(0)
+
+		// Linked on the Discord platform, and ONLY there: the blob carries no platform
+		// identity (the snowflake stays off the DTO and the token), like a password account.
+		const links = await getLinksForAccount(env.DB, accountId)
+		expect(links.map((l) => [l.platform, l.platformId])).toEqual([
+			[PlatformType.Discord, discordId],
+		])
+		const row = await env.DB.prepare('SELECT data FROM account WHERE account_id = ?1')
+			.bind(accountId)
+			.first<{ data: string }>()
+		const blob = JSON.parse(row!.data) as Record<string, unknown>
+		expect(blob.platformId).toBeUndefined()
+		expect(blob.passwordHash).toBeUndefined()
+		// Placed in Orientation like any signup.
+		const presence = await env.DB.prepare('SELECT 1 AS ok FROM presence WHERE account_id = ?1')
+			.bind(accountId)
+			.first()
+		expect(presence).not.toBeNull()
+
+		// The same Discord again is a sign-IN to that account, not a second account.
+		const again = await redeem(await assertionFor(discordId))
+		expect(again.status).toBe(200)
+		expect(again.json).not.toHaveProperty('created')
+		expect(decodePayload(again.json.access_token as string).sub).toBe(String(accountId))
+		await expect(
+			countAccountsForPlatformIdentity(env.DB, PlatformType.Discord, discordId)
+		).resolves.toBe(1)
+	})
+
+	// The stretch of the feature: a Discord-made account has no password, and a password is
+	// what signs it into the game (a sideloaded Quest has no Meta nonce to offer). The
+	// website's password form posts with an EMPTY old password the first time.
+	test('a Discord-made account can set a password and then sign in with it', async () => {
+		const created = await redeem(await assertionFor('700000000000009402'))
+		const accountId = decodePayload(created.json.access_token as string).sub as string
+		expect((await postToken(`account_id=${accountId}&password=hunter22`)).status).toBe(400)
+
+		const set = await changePassword(
+			'oldPassword=&newPassword=hunter22',
+			created.json.access_token as string
+		)
+		expect(set.status).toBe(200)
+		const login = await postToken(`grant_type=password&account_id=${accountId}&password=hunter22`)
+		expect(login.status).toBe(200)
+		expect(decodePayload(login.json.access_token as string).sub).toBe(accountId)
+	})
+
+	test('refuses an identity that opens several accounts rather than guessing', async () => {
+		await seedAccount(9403, 'TwoLinksA')
+		await seedAccount(9404, 'TwoLinksB')
+		await linkPlatformIdentity(env.DB, 9403, PlatformType.Discord, '700000000000009403', [])
+		await linkPlatformIdentity(env.DB, 9404, PlatformType.Discord, '700000000000009403', [])
+		const res = await redeem(await assertionFor('700000000000009403'))
+		expect(res.status).toBe(400)
+		expect(res.json.error_description).toBe('platform identity is linked to more than one account')
+	})
+
+	// The signup caps reach this path as they reach create_account — www forwards the
+	// browser's real address over the service binding, so the per-IP cap counts browsers.
+	test('the per-IP signup cap applies to accounts made this way', async () => {
+		const ip = '198.51.100.77'
+		for (let i = 0; i < 3; i++) {
+			const res = await redeem(await assertionFor(`70000000000000950${i}`), ip)
+			expect(res.status).toBe(200)
+			expect(res.json.created).toBe(true)
+		}
+		const fourth = await redeem(await assertionFor('700000000000009509'), ip)
+		expect(fourth.status).toBe(400)
+		expect(fourth.json.error_description).toBe('too many accounts created from this network')
+		// Signing IN from that network is untouched: the cap is on creation.
+		const existing = await redeem(await assertionFor('700000000000009500'), ip)
+		expect(existing.status).toBe(200)
+	})
+})