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Merged
kunickiaj merged 1 commit into from
May 24, 2026
+539 −13
Merged

feat(mcp): rotate refresh tokens for SDK auth #1143

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63 changes: 63 additions & 0 deletions packages/mcp-server/src/oauth.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import {
createInMemoryOAuthAccessTokenStore,
createInMemoryOAuthAuthorizationCodeStore,
createInMemoryOAuthClientsStore,
createInMemoryOAuthRefreshTokenStore,
createMcpOAuthMetadata,
createMcpProtectedResourceMetadata,
exchangeMcpOAuthAuthorizationCode,
Expand Down Expand Up @@ -715,6 +716,68 @@ describe("MCP OAuth metadata and dynamic client registration", () => {
reason: "unknown_token",
});
});

it("allows refresh-token scope downscoping without expansion", () => {
const refreshStore = createInMemoryOAuthRefreshTokenStore();
const issued = refreshStore.issueGrant({
clientId: "client-scope",
scopes: ["memory:read", "memory:write"],
});
if (!issued) throw new Error("expected refresh token grant");

const downscoped = refreshStore.rotateRefreshToken("client-scope", issued.refreshToken, {
scopes: ["memory:read"],
});
expect(downscoped).toMatchObject({ ok: true, grant: { scopes: ["memory:read"] } });
if (!downscoped.ok) throw new Error("expected refresh token downscope");
expect(
refreshStore.rotateRefreshToken("client-scope", downscoped.refreshToken, {
scopes: ["memory:admin"],
}),
).toMatchObject({ ok: false, reason: "scope_mismatch" });
});

it("cleans refresh-token hash indexes when grants are revoked", () => {
const refreshStore = createInMemoryOAuthRefreshTokenStore();
const issued = refreshStore.issueGrant({ clientId: "client-revoke" });
if (!issued) throw new Error("expected refresh token grant");
const rotated = refreshStore.rotateRefreshToken("client-revoke", issued.refreshToken);
if (!rotated.ok) throw new Error("expected refresh token rotation");

expect(refreshStore.revokeRefreshToken(rotated.refreshToken)).toBe(issued.grant.grantId);
expect(refreshStore.revokeRefreshToken(rotated.refreshToken)).toBeUndefined();
});

it("cleans every refresh-token hash for multi-rotated grants", () => {
const refreshStore = createInMemoryOAuthRefreshTokenStore();
const issued = refreshStore.issueGrant({ clientId: "client-multi" }, 1_000);
if (!issued) throw new Error("expected refresh token grant");
const first = refreshStore.rotateRefreshToken("client-multi", issued.refreshToken, {}, 2_000);
if (!first.ok) throw new Error("expected first refresh token rotation");
const second = refreshStore.rotateRefreshToken("client-multi", first.refreshToken, {}, 3_000);
if (!second.ok) throw new Error("expected second refresh token rotation");

expect(refreshStore.revokeRefreshToken(second.refreshToken, 4_000)).toBe(issued.grant.grantId);
expect(refreshStore.revokeRefreshToken(issued.refreshToken, 4_001)).toBeUndefined();
expect(refreshStore.revokeRefreshToken(first.refreshToken, 4_001)).toBeUndefined();
expect(refreshStore.revokeRefreshToken(second.refreshToken, 4_001)).toBeUndefined();
});

it("cleans every refresh-token hash for expired multi-rotated grants", () => {
const refreshStore = createInMemoryOAuthRefreshTokenStore();
const issued = refreshStore.issueGrant({ clientId: "client-expire" }, 1_000);
if (!issued) throw new Error("expected refresh token grant");
const first = refreshStore.rotateRefreshToken("client-expire", issued.refreshToken, {}, 2_000);
if (!first.ok) throw new Error("expected first refresh token rotation");
const second = refreshStore.rotateRefreshToken("client-expire", first.refreshToken, {}, 3_000);
if (!second.ok) throw new Error("expected second refresh token rotation");

const afterRefreshTtl = 31 * 24 * 60 * 60 * 1000;
expect(refreshStore.issueGrant({ clientId: "client-next" }, afterRefreshTtl)).toBeDefined();
expect(refreshStore.revokeRefreshToken(issued.refreshToken, afterRefreshTtl)).toBeUndefined();
expect(refreshStore.revokeRefreshToken(first.refreshToken, afterRefreshTtl)).toBeUndefined();
expect(refreshStore.revokeRefreshToken(second.refreshToken, afterRefreshTtl)).toBeUndefined();
});
});

function pkceS256(verifier: string): string {
Expand Down
210 changes: 210 additions & 0 deletions packages/mcp-server/src/oauth.ts
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,10 @@ const SUPPORTED_GRANT_TYPES = new Set(["authorization_code", "refresh_token"]);
const SUPPORTED_RESPONSE_TYPES = new Set(["code"]);
const AUTHORIZATION_CODE_TTL_MS = 5 * 60 * 1000;
const ACCESS_TOKEN_TTL_SECONDS = 60 * 60;
const REFRESH_TOKEN_TTL_SECONDS = 30 * 24 * 60 * 60;
const MAX_AUTHORIZATION_CODES = 100;
const MAX_ACCESS_TOKENS = 100;
const MAX_REFRESH_GRANTS = 100;
const ACCESS_TOKEN_BYTES = 32;
const ACCESS_TOKEN_BASE64URL_LENGTH = 43;
const ACCESS_TOKEN_BASE64URL = /^[A-Za-z0-9_-]{43}$/;
Expand Down Expand Up @@ -64,6 +66,7 @@ export interface OAuthAuthorizationCodeStore {

export interface AccessTokenRecord {
clientId: string;
grantId?: string;
resource?: string;
tokenHash: string;
issuedAt: number;
Expand All @@ -81,9 +84,54 @@ export interface OAuthAccessTokenStore {
clientId: string,
now?: number,
resource?: string,
grantId?: string,
): { token: string; expiresIn: number } | undefined;
verifyToken(token: string, now?: number): AccessTokenVerificationResult;
revokeToken(token: string, now?: number): boolean;
revokeTokensForGrant?(grantId: string, now?: number): number;
}

export interface RefreshTokenGrantRecord {
grantId: string;
clientId: string;
scopes: string[];
resource?: string;
currentRefreshTokenHash: string;
previousRefreshTokenHash: string | null;
issuedAt: number;
expiresAt: number;
rotatedAt: number | null;
revokedAt: number | null;
}

export type RefreshTokenRotationResult =
| { ok: true; grant: RefreshTokenGrantRecord; refreshToken: string; expiresIn: number }
| {
ok: false;
reason:
| "unknown_refresh_token"
| "expired_refresh_token"
| "revoked_refresh_token"
| "client_mismatch"
| "scope_mismatch"
| "resource_mismatch"
| "refresh_token_replay";
grantId?: string;
};

export interface OAuthRefreshTokenStore {
issueGrant(
record: { clientId: string; scopes?: string[]; resource?: string },
now?: number,
): { grant: RefreshTokenGrantRecord; refreshToken: string; expiresIn: number } | undefined;
rotateRefreshToken(
clientId: string,
refreshToken: string,
options?: { scopes?: string[]; resource?: string },
now?: number,
): RefreshTokenRotationResult;
revokeRefreshToken(token: string, now?: number): string | undefined;
revokeGrant(grantId: string, now?: number): boolean;
}

export interface McpOAuthRedirectResult {
Expand Down Expand Up @@ -193,13 +241,15 @@ export class InMemoryOAuthAccessTokenStore implements OAuthAccessTokenStore {
clientId: string,
now = Date.now(),
resource?: string,
grantId?: string,
): { token: string; expiresIn: number } | undefined {
this.#deleteInactiveTokens(now);
if (this.#tokensByHash.size >= MAX_ACCESS_TOKENS) return undefined;
const tokenBytes = randomBytes(ACCESS_TOKEN_BYTES);
const tokenHash = signOAuthAccessTokenBytes(tokenBytes, this.#tokenHashKey);
this.#tokensByHash.set(tokenHash, {
clientId,
grantId,
resource,
tokenHash,
issuedAt: now,
Expand Down Expand Up @@ -238,6 +288,16 @@ export class InMemoryOAuthAccessTokenStore implements OAuthAccessTokenStore {
return true;
}

revokeTokensForGrant(grantId: string, now = Date.now()): number {
let revoked = 0;
for (const record of this.#tokensByHash.values()) {
if (record.grantId !== grantId || record.revokedAt !== null) continue;
record.revokedAt = now;
revoked += 1;
}
return revoked;
}

#deleteInactiveTokens(now: number): void {
for (const [tokenHash, record] of this.#tokensByHash) {
if (record.expiresAt <= now || record.revokedAt !== null)
Expand All @@ -246,6 +306,133 @@ export class InMemoryOAuthAccessTokenStore implements OAuthAccessTokenStore {
}
}

export class InMemoryOAuthRefreshTokenStore implements OAuthRefreshTokenStore {
readonly #grantsById = new Map<string, RefreshTokenGrantRecord>();
readonly #grantIdsByRefreshHash = new Map<string, string>();
readonly #refreshHashesByGrantId = new Map<string, Set<string>>();
readonly #tokenHashKey = randomBytes(32);

issueGrant(
record: { clientId: string; scopes?: string[]; resource?: string },
now = Date.now(),
): { grant: RefreshTokenGrantRecord; refreshToken: string; expiresIn: number } | undefined {
this.#deleteInactiveGrants(now);
if (this.#grantsById.size >= MAX_REFRESH_GRANTS) return undefined;
const refreshToken = randomToken();
const refreshTokenHash = hashSerializedOAuthToken(refreshToken, this.#tokenHashKey);
if (!refreshTokenHash) return undefined;
const grant: RefreshTokenGrantRecord = {
grantId: randomUUID(),
clientId: record.clientId,
scopes: [...(record.scopes ?? [])],
resource: record.resource,
currentRefreshTokenHash: refreshTokenHash,
previousRefreshTokenHash: null,
issuedAt: now,
expiresAt: now + REFRESH_TOKEN_TTL_SECONDS * 1000,
rotatedAt: null,
revokedAt: null,
};
this.#grantsById.set(grant.grantId, grant);
this.#grantIdsByRefreshHash.set(refreshTokenHash, grant.grantId);
this.#refreshHashesByGrantId.set(grant.grantId, new Set([refreshTokenHash]));
return {
grant: { ...grant, scopes: [...grant.scopes] },
refreshToken,
expiresIn: REFRESH_TOKEN_TTL_SECONDS,
};
}

rotateRefreshToken(
clientId: string,
refreshToken: string,
options: { scopes?: string[]; resource?: string } = {},
now = Date.now(),
): RefreshTokenRotationResult {
const tokenHash = hashSerializedOAuthToken(refreshToken, this.#tokenHashKey);
if (!tokenHash) return { ok: false, reason: "unknown_refresh_token" };
const grantId = this.#grantIdsByRefreshHash.get(tokenHash);
if (!grantId) return { ok: false, reason: "unknown_refresh_token" };
const grant = this.#grantsById.get(grantId);
if (!grant) return { ok: false, reason: "unknown_refresh_token" };
if (grant.revokedAt !== null) return { ok: false, reason: "revoked_refresh_token", grantId };
if (grant.expiresAt <= now) {
this.revokeGrant(grantId, now);
return { ok: false, reason: "expired_refresh_token", grantId };
}
if (grant.clientId !== clientId) return { ok: false, reason: "client_mismatch", grantId };
if (!isScopeSubset(options.scopes ?? grant.scopes, grant.scopes)) {
return { ok: false, reason: "scope_mismatch", grantId };
}
if ((grant.resource ?? null) !== (options.resource ?? grant.resource ?? null)) {
return { ok: false, reason: "resource_mismatch", grantId };
}

const matchesCurrent = isSameTokenHash(grant.currentRefreshTokenHash, tokenHash);
const matchesPrevious =
grant.previousRefreshTokenHash !== null &&
isSameTokenHash(grant.previousRefreshTokenHash, tokenHash);
if (!matchesCurrent && !matchesPrevious) {
this.revokeGrant(grantId, now);
return { ok: false, reason: "refresh_token_replay", grantId };
}

const nextRefreshToken = randomToken();
const nextRefreshTokenHash = hashSerializedOAuthToken(nextRefreshToken, this.#tokenHashKey);
if (!nextRefreshTokenHash) return { ok: false, reason: "unknown_refresh_token" };
grant.scopes = [...(options.scopes ?? grant.scopes)];
grant.previousRefreshTokenHash = matchesCurrent ? grant.currentRefreshTokenHash : null;
grant.currentRefreshTokenHash = nextRefreshTokenHash;
grant.rotatedAt = now;
this.#grantIdsByRefreshHash.set(nextRefreshTokenHash, grantId);
this.#refreshHashesByGrantId.get(grantId)?.add(nextRefreshTokenHash);
return {
ok: true,
grant: { ...grant, scopes: [...grant.scopes] },
refreshToken: nextRefreshToken,
expiresIn: Math.max(0, Math.floor((grant.expiresAt - now) / 1000)),
};
}

revokeRefreshToken(token: string, now = Date.now()): string | undefined {
const tokenHash = hashSerializedOAuthToken(token, this.#tokenHashKey);
if (!tokenHash) return undefined;
const grantId = this.#grantIdsByRefreshHash.get(tokenHash);
if (!grantId) return undefined;
this.revokeGrant(grantId, now);
return grantId;
}

revokeGrant(grantId: string, now = Date.now()): boolean {
const grant = this.#grantsById.get(grantId);
if (!grant) return false;
if (grant.revokedAt !== null) return true;
grant.revokedAt = now;
this.#deleteGrantRefreshHashIndexEntries(grant);
return true;
}

#deleteInactiveGrants(now: number): void {
for (const [grantId, grant] of this.#grantsById) {
if (grant.expiresAt > now && grant.revokedAt === null) continue;
this.#grantsById.delete(grantId);
this.#deleteGrantRefreshHashIndexEntries(grant);
}
}

#deleteGrantRefreshHashIndexEntries(grant: RefreshTokenGrantRecord): void {
const refreshHashes = this.#refreshHashesByGrantId.get(grant.grantId);
if (refreshHashes) {
for (const refreshHash of refreshHashes) this.#grantIdsByRefreshHash.delete(refreshHash);
this.#refreshHashesByGrantId.delete(grant.grantId);
return;
}
this.#grantIdsByRefreshHash.delete(grant.currentRefreshTokenHash);
if (grant.previousRefreshTokenHash)
this.#grantIdsByRefreshHash.delete(grant.previousRefreshTokenHash);
}
}

export function createInMemoryOAuthClientsStore(): OAuthRegisteredClientsStore {
return new InMemoryOAuthClientsStore();
}
Expand All @@ -258,6 +445,10 @@ export function createInMemoryOAuthAccessTokenStore(): OAuthAccessTokenStore {
return new InMemoryOAuthAccessTokenStore();
}

export function createInMemoryOAuthRefreshTokenStore(): OAuthRefreshTokenStore {
return new InMemoryOAuthRefreshTokenStore();
}

export function createMcpOAuthMetadata(options: McpOAuthMetadataOptions): OAuthMetadata {
const mcpUrl = normalizeMcpPublicUrl(options.mcpUrl);
const issuerUrl = getOriginUrl(mcpUrl);
Expand Down Expand Up @@ -585,11 +776,25 @@ function decodeOAuthAccessToken(serialized: string): Buffer | null {
return bytes;
}

function randomToken(): string {
return randomBytes(ACCESS_TOKEN_BYTES).toString("base64url");
}

function hashSerializedOAuthToken(serialized: string, key: Buffer): string | null {
const tokenBytes = decodeOAuthAccessToken(serialized);
if (!tokenBytes) return null;
return signOAuthToken(tokenBytes, key);
}

// Compute the HMAC-SHA256 signature of the binary access-token material using
// the per-store random key. This is an integrity signature over a random
// 256-bit value, not password hashing; tokens are validated by re-signing the
// presented bytes and comparing the digest to the stored signature.
function signOAuthAccessTokenBytes(material: Buffer, key: Buffer): string {
return signOAuthToken(material, key);
}

function signOAuthToken(material: Buffer | string, key: Buffer): string {
return createHmac("sha256", key).update(material).digest("base64url");
}

Expand All @@ -599,6 +804,11 @@ function isSameTokenHash(left: string, right: string): boolean {
return leftBuffer.length === rightBuffer.length && timingSafeEqual(leftBuffer, rightBuffer);
}

function isScopeSubset(requested: string[], granted: string[]): boolean {
const grantedScopes = new Set(granted);
return requested.every((scope) => grantedScopes.has(scope));
}

function createMetadataOnlyProvider(
clientsStore: OAuthRegisteredClientsStore,
): OAuthServerProvider {
Expand Down
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