Package org.apache.juneau.rest.server.mcp.v20260728

Class McpAudienceValidator

java.lang.Object

org.apache.juneau.rest.server.mcp.v20260728.McpAudienceValidator

public final class McpAudienceValidator
extends Object

RFC 8707 audience enforcement — the confused-deputy defense pairing with the MCP client's resource indicator.

Confirms that a validated access token was actually minted for this resource by checking that the token's aud or resource claim contains this server's resource identifier, rejecting a token whose audience targets a different resource.

Claims requirement:

Gate-level enforcement applies to a ClaimsPrincipal (as produced by JwtTokenValidator and OAuth introspection). A validator returning a bare Principal that exposes no claims cannot be checked at the gate; the requireAudienceClaim flag decides the disposition:

• true (the default) — fail-closed: a claims-less principal is rejected, so the confused-deputy defense is never silently a no-op.
• false — opt-out: a claims-less principal passes, delegating audience enforcement to the validator itself (e.g. JwtTokenValidator enforcing aud internally, or an introspection AS that legitimately omits aud).

Since:

10.0.0

Method Summary

Modifier and Type	Method	Description
static boolean	matches(Principal principal, String expectedAudience, boolean requireAudienceClaim)	Returns whether the principal's token audience matches the expected resource identifier.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

matches

public static boolean matches(Principal principal,
 String expectedAudience,
 boolean requireAudienceClaim)

Returns whether the principal's token audience matches the expected resource identifier.

Parameters:

principal - The authenticated principal. May be null (returns false).

expectedAudience - The expected audience (this server's resource identifier). Must not be null or blank.

requireAudienceClaim - Whether a principal exposing no claims is rejected (fail-closed) rather than passed (see McpResourceServerConfig.isRequireAudienceClaim()).

Returns:

true if the audience matches, or the principal exposes no claims and requireAudienceClaim is false; false if the principal is null, exposes no claims while requireAudienceClaim is true, or carries claims whose aud/resource do not include the expected audience.