LibreChat/api/server/routes/__tests__
Denis Palnitsky 8ed0bcf5ca
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♻️ fix: Reuse Existing MCP OAuth Client Registrations to Prevent client_id Mismatch (#11925)
* fix: reuse existing OAuth client registrations to prevent client_id mismatch

When using auto-discovered OAuth (DCR), LibreChat calls /register on every
flow initiation, getting a new client_id each time. When concurrent
connections or reconnections happen, the client_id used during /authorize
differs from the one used during /token, causing the server to reject the
exchange.

Before registering a new client, check if a valid client registration
already exists in the database and reuse it.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Handle re-registration of OAuth clients when redirect_uri changes

* Add undefined fields for logo_uri and tos_uri in OAuth metadata tests

* test: add client registration reuse tests for horizontal scaling race condition

Reproduces the client_id mismatch bug that occurs in multi-replica deployments
where concurrent initiateOAuthFlow calls each register a new OAuth client.
Tests verify that the findToken-based client reuse prevents re-registration.

* fix: address review findings for client registration reuse

- Fix empty redirect_uris bug: invert condition so missing/empty
  redirect_uris triggers re-registration instead of silent reuse
- Revert undocumented config?.redirect_uri in auto-discovery path
- Change DB error logging from debug to warn for operator visibility
- Fix import order: move package type import to correct section
- Remove redundant type cast and misleading JSDoc comment
- Test file: remove dead imports, restore process.env.DOMAIN_SERVER,
  rename describe blocks, add empty redirect_uris edge case test,
  add concurrent reconnection test with pre-seeded token,
  scope documentation to reconnection stabilization

* fix: resolve type check errors for OAuthClientInformation redirect_uris

The SDK's OAuthClientInformation type lacks redirect_uris (only on
OAuthClientInformationFull). Cast to the local OAuthClientInformation
type in handler.ts when accessing deserialized client info from DB,
and use intersection types in tests for clientInfo with redirect_uris.

* fix: address follow-up review findings R1, R2, R3

- R1: Move `import type { TokenMethods }` to the type-imports section,
  before local types, per CLAUDE.md import order rules
- R2: Add unit test for empty redirect_uris in handler.test.ts to
  verify the inverted condition triggers re-registration
- R3: Use delete for process.env.DOMAIN_SERVER restoration when the
  original value was undefined to avoid coercion to string "undefined"

* fix: clear stale client registration on OAuth flow failure

When a stored client_id is no longer recognized by the OAuth server,
the flow fails but the stale client stays in MongoDB, causing every
retry to reuse the same invalid registration in an infinite loop.

On OAuth failure, clear the stored client registration so the next
attempt falls through to fresh Dynamic Client Registration.

- Add MCPTokenStorage.deleteClientRegistration() for targeted cleanup
- Call it from MCPConnectionFactory's OAuth failure path
- Add integration test proving recovery from stale client reuse

* fix: validate auth server identity and target cleanup to reused clients

- Gate client reuse on authorization server identity: compare stored
  issuer against freshly discovered metadata before reusing, preventing
  wrong-client reuse when the MCP server switches auth providers
- Add reusedStoredClient flag to MCPOAuthFlowMetadata so cleanup only
  runs when the failed flow actually reused a stored registration,
  not on unrelated failures (timeouts, user-denied consent, etc.)
- Add cleanup in returnOnOAuth path: when a prior flow that reused a
  stored client is detected as failed, clear the stale registration
  before re-initiating
- Add tests for issuer mismatch and reusedStoredClient flag assertions

* fix: address minor review findings N3, N5, N6

- N3: Type deleteClientRegistration param as TokenMethods['deleteTokens']
  instead of Promise<unknown>
- N5: Elevate deletion failure logging from debug to warn for operator
  visibility when stale client cleanup fails
- N6: Use getLogPrefix() instead of hardcoded log prefix to respect
  system-user privacy convention

* fix: correct stale-client cleanup in both OAuth paths

- Blocking path: remove result?.clientInfo guard that made cleanup
  unreachable (handleOAuthRequired returns null on failure, so
  result?.clientInfo was always false in the failure branch)
- returnOnOAuth path: only clear stored client when the prior flow
  status is FAILED, not on COMPLETED or PENDING flows, to avoid
  deleting valid registrations during normal flow replacement

* fix: remove redundant cast on clientMetadata

clientMetadata is already typed as Record<string, unknown>; the
as Record<string, unknown> cast was a no-op.

* fix: thread reusedStoredClient through return type instead of re-reading flow state

FlowStateManager.createFlow() deletes FAILED flow state before
rejecting, so getFlowState() after handleOAuthRequired() returns null
would find nothing — making the stale-client cleanup dead code.

Fix: hoist reusedStoredClient flag from flowMetadata into a local
variable, include it in handleOAuthRequired()'s return type (both
success and catch paths), and use result.reusedStoredClient directly
in the caller instead of a second getFlowState() round-trip.

* fix: selective stale-client cleanup in returnOnOAuth path

The returnOnOAuth cleanup was unreliable: it depended on reading
FAILED flow state, but FlowStateManager.monitorFlow() deletes FAILED
state before rejecting. Move cleanup into createFlow's catch handler
where flowMetadata.reusedStoredClient is still in scope.

Make cleanup selective in both paths: add isClientRejection() helper
that only matches errors indicating the OAuth server rejected the
client_id (invalid_client, unauthorized_client, client not found).
Timeouts, user-cancelled flows, and other transient failures no
longer wipe valid stored registrations.

Thread the error from handleOAuthRequired() through the return type
so the blocking path can also check isClientRejection().

* fix: tighten isClientRejection heuristic

Narrow 'client_id' match to 'client_id mismatch' to avoid
false-positive cleanup on unrelated errors that happen to
mention client_id.

* test: add isClientRejection tests and enforced client_id on test server

- Add isClientRejection unit tests: invalid_client, unauthorized_client,
  client_id mismatch, client not found, unknown client, and negative
  cases (timeout, flow state not found, user denied, null, undefined)
- Enhance OAuth test server with enforceClientId option: binds auth
  codes to the client_id that initiated /authorize, rejects token
  exchange with mismatched or unregistered client_id (401 invalid_client)
- Add integration tests proving the test server correctly rejects
  stale client_ids and accepts matching ones at /token

* fix: issuer validation, callback error propagation, and cleanup DRY

- Issuer check: re-register when storedIssuer is absent or non-string
  instead of silently reusing. Narrows unknown type with typeof guard
  and inverts condition so missing issuer → fresh DCR (safer default).
- OAuth callback route: call failFlow with the OAuth error when the
  authorization server redirects back with error= parameter, so the
  waiting flow receives the actual rejection instead of timing out.
  This lets isClientRejection match stale-client errors correctly.
- Extract duplicated cleanup block to clearStaleClientIfRejected()
  private method, called from both returnOnOAuth and blocking paths.
- Test fixes: add issuer to stored metadata in reuse tests, reset
  server to undefined in afterEach to prevent double-close.

* fix: gate failFlow behind callback validation, propagate reusedStoredClient on join

- OAuth callback: move failFlow call to after CSRF/session/active-flow
  validation so an attacker with only a leaked state parameter cannot
  force-fail a flow without passing the same integrity checks required
  for legitimate callbacks
- PENDING join path: propagate reusedStoredClient from flow metadata
  into the return object so joiners can trigger stale-client cleanup
  if the joined flow later fails with a client rejection

* fix: restore early oauthError/code redirects, gate only failFlow behind CSRF

The previous restructuring moved oauthError and missing-code checks
behind CSRF validation, breaking tests that expect those redirects
without cookies. The redirect itself is harmless (just shows an error
page). Only the failFlow call needs CSRF gating to prevent DoS.

Restructure: oauthError check stays early (redirects immediately),
but failFlow inside it runs the full CSRF/session/active-flow
validation before marking the flow as FAILED.

* fix: require deleteTokens for client reuse, add missing import in MCP.js

Client registration reuse without cleanup capability creates a
permanent failure loop: if the reused client is stale, the code
detects the rejection but cannot clear the stored registration
because deleteTokens is missing, so every retry reuses the same
broken client_id.

- MCPConnectionFactory: only pass findToken to initiateOAuthFlow
  when deleteTokens is also available, ensuring reuse is only
  enabled when recovery is possible
- api/server/services/MCP.js: add deleteTokens to the tokenMethods
  object (was the only MCP call site missing it)

* fix: set reusedStoredClient before createFlow in joined-flow path

When joining a PENDING flow, reusedStoredClient was only set on the
success return but not before the await. If createFlow throws (e.g.
invalid_client during token exchange), the outer catch returns the
local variable which was still false, skipping stale-client cleanup.

* fix: require browser binding (CSRF/session) for failFlow on OAuth error

hasActiveFlow only proves a PENDING flow exists, not that the caller
is the same browser that initiated it. An attacker with a leaked state
could force-fail the flow without any user binding. Require hasCsrf or
hasSession before calling failFlow on the oauthError path.

* fix: guard findToken with deleteTokens check in blocking OAuth path

Match the returnOnOAuth path's defense-in-depth: only enable client
registration reuse when deleteTokens is also available, ensuring
cleanup is possible if the reused client turns out to be stale.

* fix: address review findings — tests, types, normalization, docs

- Add deleteTokens method to InMemoryTokenStore matching TokenMethods
  contract; update test call site from deleteToken to deleteTokens
- Add MCPConnectionFactory test: returnOnOAuth flow fails with
  invalid_client → clearStaleClientIfRejected invoked automatically
- Add mcp.spec.js tests: OAuth error with CSRF → failFlow called;
  OAuth error without cookies → failFlow NOT called (DoS prevention)
- Add JSDoc to isClientRejection with RFC 6749 and vendor attribution
- Add inline comment explaining findToken/deleteTokens coupling guard
- Normalize issuer comparison: strip trailing slashes to prevent
  spurious re-registrations from URL formatting differences
- Fix dead-code: use local reusedStoredClient variable in PENDING
  join return instead of re-reading flowMeta

* fix: address final review nits N1-N4

- N1: Add session cookie failFlow test — validates the hasSession
  branch triggers failFlow on OAuth error callback
- N2: Replace setTimeout(50) with setImmediate for microtask drain
- N3: Add 'unknown client' attribution to isClientRejection JSDoc
- N4: Remove dead getFlowState mock from failFlow tests

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Danny Avila <danny@librechat.ai>
2026-04-03 22:15:08 -04:00
..
config.spec.js ⚖️ refactor: Split Config Route into Unauthenticated and Authenticated Paths (#12490) 2026-03-31 19:22:51 -04:00
convos-duplicate-ratelimit.spec.js 🗑️ chore: Remove Action Test Suite and Update Mock Implementations (#12268) 2026-03-21 14:28:55 -04:00
convos-import.spec.js 📏 refactor: Add File Size Limits to Conversation Imports (#12221) 2026-03-14 03:06:29 -04:00
convos.spec.js 📦 refactor: Consolidate DB models, encapsulating Mongoose usage in data-schemas (#11830) 2026-03-21 14:28:53 -04:00
grants.spec.js ⛩️ feat: Admin Grants API Endpoints (#12438) 2026-03-30 16:49:23 -04:00
keys.spec.js 🔱 chore: Harden API Routes Against IDOR and DoS Attacks (#11760) 2026-02-12 18:08:24 -05:00
ldap.spec.js 🧹 chore: Cleanup Logger and Utility Imports (#9935) 2025-10-01 23:30:47 -04:00
mcp.spec.js ♻️ fix: Reuse Existing MCP OAuth Client Registrations to Prevent client_id Mismatch (#11925) 2026-04-03 22:15:08 -04:00
messages-delete.spec.js 🗑️ chore: Remove Action Test Suite and Update Mock Implementations (#12268) 2026-03-21 14:28:55 -04:00
roles.spec.js 🔨 fix: Custom Role Permissions (#12528) 2026-04-03 13:24:11 -04:00
static.spec.js 🗂️ fix: Disable express-static-gzip for Uploaded Images (#8307) 2025-07-11 16:51:53 -04:00