chore: import upstream snapshot with attribution

tests/client/auth/extensions/test_client_credentials.py

@@ -0,0 +1,503 @@
+import urllib.parse
+import warnings
+
+import jwt
+import pytest
+from pydantic import AnyHttpUrl, AnyUrl
+
+from mcp.client.auth.extensions.client_credentials import (
+    ClientCredentialsOAuthProvider,
+    JWTParameters,
+    PrivateKeyJWTOAuthProvider,
+    RFC7523OAuthClientProvider,
+    SignedJWTParameters,
+    static_assertion_provider,
+)
+from mcp.shared.auth import (
+    AuthorizationCodeResult,
+    OAuthClientInformationFull,
+    OAuthClientMetadata,
+    OAuthMetadata,
+    OAuthToken,
+)
+from mcp.shared.exceptions import MCPDeprecationWarning
+
+
+class MockTokenStorage:
+    """Mock token storage for testing."""
+
+    def __init__(self):
+        self._tokens: OAuthToken | None = None
+        self._client_info: OAuthClientInformationFull | None = None
+
+    async def get_tokens(self) -> OAuthToken | None:
+        return self._tokens
+
+    async def set_tokens(self, tokens: OAuthToken) -> None:  # pragma: no cover
+        self._tokens = tokens
+
+    async def get_client_info(self) -> OAuthClientInformationFull | None:  # pragma: no cover
+        return self._client_info
+
+    async def set_client_info(self, client_info: OAuthClientInformationFull) -> None:  # pragma: no cover
+        self._client_info = client_info
+
+
+@pytest.fixture
+def mock_storage():
+    return MockTokenStorage()
+
+
+@pytest.fixture
+def client_metadata():
+    return OAuthClientMetadata(
+        client_name="Test Client",
+        client_uri=AnyHttpUrl("https://example.com"),
+        redirect_uris=[AnyUrl("http://localhost:3030/callback")],
+        scope="read write",
+    )
+
+
+@pytest.fixture
+def rfc7523_oauth_provider(client_metadata: OAuthClientMetadata, mock_storage: MockTokenStorage):
+    async def redirect_handler(url: str) -> None:  # pragma: no cover
+        """Mock redirect handler."""
+        pass
+
+    async def callback_handler() -> AuthorizationCodeResult:  # pragma: no cover
+        """Mock callback handler."""
+        return AuthorizationCodeResult(code="test_auth_code", state="test_state")
+
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", MCPDeprecationWarning)
+        return RFC7523OAuthClientProvider(
+            server_url="https://api.example.com/v1/mcp",
+            client_metadata=client_metadata,
+            storage=mock_storage,
+            redirect_handler=redirect_handler,
+            callback_handler=callback_handler,
+        )
+
+
+class TestOAuthFlowClientCredentials:
+    """Test OAuth flow behavior for client credentials flows."""
+
+    @pytest.mark.anyio
+    async def test_token_exchange_request_jwt_predefined(self, rfc7523_oauth_provider: RFC7523OAuthClientProvider):
+        """Test token exchange request building with a predefined JWT assertion."""
+        # Set up required context
+        rfc7523_oauth_provider.context.client_info = OAuthClientInformationFull(
+            grant_types=["urn:ietf:params:oauth:grant-type:jwt-bearer"],
+            token_endpoint_auth_method="private_key_jwt",
+            redirect_uris=None,
+            scope="read write",
+        )
+        rfc7523_oauth_provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+            registration_endpoint=AnyHttpUrl("https://api.example.com/register"),
+        )
+        rfc7523_oauth_provider.context.client_metadata = rfc7523_oauth_provider.context.client_info
+        rfc7523_oauth_provider.context.protocol_version = "2025-06-18"
+        rfc7523_oauth_provider.jwt_parameters = JWTParameters(
+            # https://www.jwt.io
+            assertion="eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.KMUFsIDTnFmyG3nMiGM6H9FNFUROf3wh7SmqJp-QV30"
+        )
+
+        request = await rfc7523_oauth_provider._exchange_token_jwt_bearer()
+
+        assert request.method == "POST"
+        assert str(request.url) == "https://api.example.com/token"
+        assert request.headers["Content-Type"] == "application/x-www-form-urlencoded"
+
+        # Check form data
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer" in content
+        assert "scope=read write" in content
+        assert "resource=https://api.example.com/v1/mcp" in content
+        assert (
+            "assertion=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.KMUFsIDTnFmyG3nMiGM6H9FNFUROf3wh7SmqJp-QV30"
+            in content
+        )
+
+    @pytest.mark.anyio
+    async def test_token_exchange_request_jwt(self, rfc7523_oauth_provider: RFC7523OAuthClientProvider):
+        """Test token exchange request building wiith a generated JWT assertion."""
+        # Set up required context
+        rfc7523_oauth_provider.context.client_info = OAuthClientInformationFull(
+            grant_types=["urn:ietf:params:oauth:grant-type:jwt-bearer"],
+            token_endpoint_auth_method="private_key_jwt",
+            redirect_uris=None,
+            scope="read write",
+        )
+        rfc7523_oauth_provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+            registration_endpoint=AnyHttpUrl("https://api.example.com/register"),
+        )
+        rfc7523_oauth_provider.context.client_metadata = rfc7523_oauth_provider.context.client_info
+        rfc7523_oauth_provider.context.protocol_version = "2025-06-18"
+        rfc7523_oauth_provider.jwt_parameters = JWTParameters(
+            issuer="foo",
+            subject="1234567890",
+            claims={
+                "name": "John Doe",
+                "admin": True,
+                "iat": 1516239022,
+            },
+            jwt_signing_algorithm="HS256",
+            jwt_signing_key="a-string-secret-at-least-256-bits-long",
+            jwt_lifetime_seconds=300,
+        )
+
+        request = await rfc7523_oauth_provider._exchange_token_jwt_bearer()
+
+        assert request.method == "POST"
+        assert str(request.url) == "https://api.example.com/token"
+        assert request.headers["Content-Type"] == "application/x-www-form-urlencoded"
+
+        # Check form data
+        content = urllib.parse.unquote_plus(request.content.decode()).split("&")
+        assert "grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer" in content
+        assert "scope=read write" in content
+        assert "resource=https://api.example.com/v1/mcp" in content
+
+        # Check assertion
+        assertion = next(param for param in content if param.startswith("assertion="))[len("assertion=") :]
+        claims = jwt.decode(
+            assertion,
+            key="a-string-secret-at-least-256-bits-long",
+            algorithms=["HS256"],
+            audience="https://api.example.com/",
+            subject="1234567890",
+            issuer="foo",
+            verify=True,
+        )
+        assert claims["name"] == "John Doe"
+        assert claims["admin"]
+        assert claims["iat"] == 1516239022
+
+
+class TestClientCredentialsOAuthProvider:
+    """Test ClientCredentialsOAuthProvider."""
+
+    @pytest.mark.anyio
+    async def test_init_sets_client_info(self, mock_storage: MockTokenStorage):
+        """Test that _initialize sets client_info."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+        )
+
+        # client_info is set during _initialize
+        await provider._initialize()
+
+        assert provider.context.client_info is not None
+        assert provider.context.client_info.client_id == "test-client-id"
+        assert provider.context.client_info.client_secret == "test-client-secret"
+        assert provider.context.client_info.grant_types == ["client_credentials"]
+        assert provider.context.client_info.token_endpoint_auth_method == "client_secret_basic"
+
+    @pytest.mark.anyio
+    async def test_init_with_scopes(self, mock_storage: MockTokenStorage):
+        """Test that constructor accepts scopes."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+            scopes="read write",
+        )
+
+        await provider._initialize()
+        assert provider.context.client_info is not None
+        assert provider.context.client_info.scope == "read write"
+
+    @pytest.mark.anyio
+    async def test_init_with_client_secret_post(self, mock_storage: MockTokenStorage):
+        """Test that constructor accepts client_secret_post auth method."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+            token_endpoint_auth_method="client_secret_post",
+        )
+
+        await provider._initialize()
+        assert provider.context.client_info is not None
+        assert provider.context.client_info.token_endpoint_auth_method == "client_secret_post"
+
+    @pytest.mark.anyio
+    async def test_exchange_token_client_credentials(self, mock_storage: MockTokenStorage):
+        """Test token exchange request building."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+            scopes="read write",
+        )
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+        )
+        provider.context.protocol_version = "2025-06-18"
+
+        request = await provider._perform_authorization()
+
+        assert request.method == "POST"
+        assert str(request.url) == "https://api.example.com/token"
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        assert "scope=read write" in content
+        assert "resource=https://api.example.com/v1/mcp" in content
+
+    @pytest.mark.anyio
+    async def test_exchange_token_client_secret_post_includes_client_id(self, mock_storage: MockTokenStorage):
+        """Test that client_secret_post includes both client_id and client_secret in body (RFC 6749 §2.3.1)."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+            token_endpoint_auth_method="client_secret_post",
+            scopes="read write",
+        )
+        await provider._initialize()
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+        )
+        provider.context.protocol_version = "2025-06-18"
+
+        request = await provider._perform_authorization()
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        assert "client_id=test-client-id" in content
+        assert "client_secret=test-client-secret" in content
+        # Should NOT have Basic auth header
+        assert "Authorization" not in request.headers
+
+    @pytest.mark.anyio
+    async def test_exchange_token_client_secret_post_without_client_id(self, mock_storage: MockTokenStorage):
+        """Test client_secret_post skips body credentials when client_id is None."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="placeholder",
+            client_secret="test-client-secret",
+            token_endpoint_auth_method="client_secret_post",
+            scopes="read write",
+        )
+        await provider._initialize()
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+        )
+        provider.context.protocol_version = "2025-06-18"
+        # Override client_info to have client_id=None (edge case)
+        provider.context.client_info = OAuthClientInformationFull(
+            redirect_uris=None,
+            client_id=None,
+            client_secret="test-client-secret",
+            grant_types=["client_credentials"],
+            token_endpoint_auth_method="client_secret_post",
+            scope="read write",
+        )
+
+        request = await provider._perform_authorization()
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        # Neither client_id nor client_secret should be in body since client_id is None
+        # (RFC 6749 §2.3.1 requires both for client_secret_post)
+        assert "client_id=" not in content
+        assert "client_secret=" not in content
+        assert "Authorization" not in request.headers
+
+    @pytest.mark.anyio
+    async def test_exchange_token_without_scopes(self, mock_storage: MockTokenStorage):
+        """Test token exchange without scopes."""
+        provider = ClientCredentialsOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="test-client-id",
+            client_secret="test-client-secret",
+        )
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://api.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://api.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://api.example.com/token"),
+        )
+        provider.context.protocol_version = "2024-11-05"  # Old version - no resource param
+
+        request = await provider._perform_authorization()
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        assert "scope=" not in content
+        assert "resource=" not in content
+
+
+class TestPrivateKeyJWTOAuthProvider:
+    """Test PrivateKeyJWTOAuthProvider."""
+
+    @pytest.mark.anyio
+    async def test_init_sets_client_info(self, mock_storage: MockTokenStorage):
+        """Test that _initialize sets client_info."""
+
+        async def mock_assertion_provider(audience: str) -> str:  # pragma: no cover
+            return "mock-jwt"
+
+        provider = PrivateKeyJWTOAuthProvider(
+            server_url="https://api.example.com",
+            storage=mock_storage,
+            client_id="test-client-id",
+            assertion_provider=mock_assertion_provider,
+        )
+
+        # client_info is set during _initialize
+        await provider._initialize()
+
+        assert provider.context.client_info is not None
+        assert provider.context.client_info.client_id == "test-client-id"
+        assert provider.context.client_info.grant_types == ["client_credentials"]
+        assert provider.context.client_info.token_endpoint_auth_method == "private_key_jwt"
+
+    @pytest.mark.anyio
+    async def test_exchange_token_client_credentials(self, mock_storage: MockTokenStorage):
+        """Test token exchange request building with assertion provider."""
+
+        async def mock_assertion_provider(audience: str) -> str:
+            return f"jwt-for-{audience}"
+
+        provider = PrivateKeyJWTOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="test-client-id",
+            assertion_provider=mock_assertion_provider,
+            scopes="read write",
+        )
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://auth.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://auth.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://auth.example.com/token"),
+        )
+        provider.context.protocol_version = "2025-06-18"
+
+        request = await provider._perform_authorization()
+
+        assert request.method == "POST"
+        assert str(request.url) == "https://auth.example.com/token"
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        assert "client_assertion=jwt-for-https://auth.example.com/" in content
+        assert "client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer" in content
+        assert "scope=read write" in content
+
+    @pytest.mark.anyio
+    async def test_exchange_token_without_scopes(self, mock_storage: MockTokenStorage):
+        """Test token exchange without scopes."""
+
+        async def mock_assertion_provider(audience: str) -> str:
+            return f"jwt-for-{audience}"
+
+        provider = PrivateKeyJWTOAuthProvider(
+            server_url="https://api.example.com/v1/mcp",
+            storage=mock_storage,
+            client_id="test-client-id",
+            assertion_provider=mock_assertion_provider,
+        )
+        provider.context.oauth_metadata = OAuthMetadata(
+            issuer=AnyHttpUrl("https://auth.example.com"),
+            authorization_endpoint=AnyHttpUrl("https://auth.example.com/authorize"),
+            token_endpoint=AnyHttpUrl("https://auth.example.com/token"),
+        )
+        provider.context.protocol_version = "2024-11-05"  # Old version - no resource param
+
+        request = await provider._perform_authorization()
+
+        content = urllib.parse.unquote_plus(request.content.decode())
+        assert "grant_type=client_credentials" in content
+        assert "scope=" not in content
+        assert "resource=" not in content
+
+
+class TestSignedJWTParameters:
+    """Test SignedJWTParameters."""
+
+    @pytest.mark.anyio
+    async def test_create_assertion_provider(self):
+        """Test that create_assertion_provider creates valid JWTs."""
+        params = SignedJWTParameters(
+            issuer="test-issuer",
+            subject="test-subject",
+            signing_key="a-string-secret-at-least-256-bits-long",
+            signing_algorithm="HS256",
+            lifetime_seconds=300,
+        )
+
+        provider = params.create_assertion_provider()
+        assertion = await provider("https://auth.example.com")
+
+        claims = jwt.decode(
+            assertion,
+            key="a-string-secret-at-least-256-bits-long",
+            algorithms=["HS256"],
+            audience="https://auth.example.com",
+        )
+        assert claims["iss"] == "test-issuer"
+        assert claims["sub"] == "test-subject"
+        assert claims["aud"] == "https://auth.example.com"
+        assert "exp" in claims
+        assert "iat" in claims
+        assert "jti" in claims
+
+    @pytest.mark.anyio
+    async def test_create_assertion_provider_with_additional_claims(self):
+        """Test that additional_claims are included in the JWT."""
+        params = SignedJWTParameters(
+            issuer="test-issuer",
+            subject="test-subject",
+            signing_key="a-string-secret-at-least-256-bits-long",
+            signing_algorithm="HS256",
+            additional_claims={"custom": "value"},
+        )
+
+        provider = params.create_assertion_provider()
+        assertion = await provider("https://auth.example.com")
+
+        claims = jwt.decode(
+            assertion,
+            key="a-string-secret-at-least-256-bits-long",
+            algorithms=["HS256"],
+            audience="https://auth.example.com",
+        )
+        assert claims["custom"] == "value"
+
+
+class TestStaticAssertionProvider:
+    """Test static_assertion_provider helper."""
+
+    @pytest.mark.anyio
+    async def test_returns_static_token(self):
+        """Test that static_assertion_provider returns the same token regardless of audience."""
+        token = "my-static-jwt-token"
+        provider = static_assertion_provider(token)
+
+        result1 = await provider("https://auth1.example.com")
+        result2 = await provider("https://auth2.example.com")
+
+        assert result1 == token
+        assert result2 == token