Add support for serverside oauth (#255)
Co-authored-by: David Soria Parra <davidsp@anthropic.com> Co-authored-by: Basil Hosmer <basil@anthropic.com> Co-authored-by: ihrpr <inna@anthropic.com>
This commit is contained in:
Peter Raboud
GitHub
parent
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commit
2210c1be18
1 changed files with 4120 additions and 22 deletions
264
src/mcp/server/auth/handlers/token.py
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264
src/mcp/server/auth/handlers/token.py
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import base64
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import hashlib
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import time
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from dataclasses import dataclass
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from typing import Annotated, Any, Literal
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from pydantic import AnyHttpUrl, BaseModel, Field, RootModel, ValidationError
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from starlette.requests import Request
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from mcp.server.auth.errors import (
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stringify_pydantic_error,
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)
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from mcp.server.auth.json_response import PydanticJSONResponse
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from mcp.server.auth.middleware.client_auth import (
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AuthenticationError,
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ClientAuthenticator,
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)
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from mcp.server.auth.provider import (
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OAuthAuthorizationServerProvider,
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TokenError,
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TokenErrorCode,
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)
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from mcp.shared.auth import OAuthToken
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class AuthorizationCodeRequest(BaseModel):
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# See https://datatracker.ietf.org/doc/html/rfc6749#section-4.1.3
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grant_type: Literal["authorization_code"]
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code: str = Field(..., description="The authorization code")
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redirect_uri: AnyHttpUrl | None = Field(
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None, description="Must be the same as redirect URI provided in /authorize"
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)
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client_id: str
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# we use the client_secret param, per https://datatracker.ietf.org/doc/html/rfc6749#section-2.3.1
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client_secret: str | None = None
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# See https://datatracker.ietf.org/doc/html/rfc7636#section-4.5
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code_verifier: str = Field(..., description="PKCE code verifier")
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class RefreshTokenRequest(BaseModel):
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# See https://datatracker.ietf.org/doc/html/rfc6749#section-6
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grant_type: Literal["refresh_token"]
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refresh_token: str = Field(..., description="The refresh token")
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scope: str | None = Field(None, description="Optional scope parameter")
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client_id: str
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# we use the client_secret param, per https://datatracker.ietf.org/doc/html/rfc6749#section-2.3.1
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client_secret: str | None = None
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class TokenRequest(
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RootModel[
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Annotated[
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AuthorizationCodeRequest | RefreshTokenRequest,
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Field(discriminator="grant_type"),
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]
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]
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):
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root: Annotated[
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AuthorizationCodeRequest | RefreshTokenRequest,
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Field(discriminator="grant_type"),
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]
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class TokenErrorResponse(BaseModel):
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"""
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See https://datatracker.ietf.org/doc/html/rfc6749#section-5.2
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"""
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error: TokenErrorCode
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error_description: str | None = None
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error_uri: AnyHttpUrl | None = None
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class TokenSuccessResponse(RootModel[OAuthToken]):
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# this is just a wrapper over OAuthToken; the only reason we do this
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# is to have some separation between the HTTP response type, and the
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# type returned by the provider
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root: OAuthToken
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@dataclass
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class TokenHandler:
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provider: OAuthAuthorizationServerProvider[Any, Any, Any]
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client_authenticator: ClientAuthenticator
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def response(self, obj: TokenSuccessResponse | TokenErrorResponse):
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status_code = 200
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if isinstance(obj, TokenErrorResponse):
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status_code = 400
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return PydanticJSONResponse(
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content=obj,
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status_code=status_code,
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headers={
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"Cache-Control": "no-store",
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"Pragma": "no-cache",
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},
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)
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async def handle(self, request: Request):
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try:
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form_data = await request.form()
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token_request = TokenRequest.model_validate(dict(form_data)).root
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except ValidationError as validation_error:
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return self.response(
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TokenErrorResponse(
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error="invalid_request",
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error_description=stringify_pydantic_error(validation_error),
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)
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)
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try:
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client_info = await self.client_authenticator.authenticate(
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client_id=token_request.client_id,
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client_secret=token_request.client_secret,
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)
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except AuthenticationError as e:
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return self.response(
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TokenErrorResponse(
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error="unauthorized_client",
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error_description=e.message,
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)
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)
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if token_request.grant_type not in client_info.grant_types:
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return self.response(
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TokenErrorResponse(
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error="unsupported_grant_type",
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error_description=(
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f"Unsupported grant type (supported grant types are "
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f"{client_info.grant_types})"
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),
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)
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)
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tokens: OAuthToken
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match token_request:
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case AuthorizationCodeRequest():
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auth_code = await self.provider.load_authorization_code(
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client_info, token_request.code
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)
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if auth_code is None or auth_code.client_id != token_request.client_id:
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# if code belongs to different client, pretend it doesn't exist
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return self.response(
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TokenErrorResponse(
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error="invalid_grant",
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error_description="authorization code does not exist",
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)
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)
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# make auth codes expire after a deadline
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# see https://datatracker.ietf.org/doc/html/rfc6749#section-10.5
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if auth_code.expires_at < time.time():
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return self.response(
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TokenErrorResponse(
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error="invalid_grant",
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error_description="authorization code has expired",
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)
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)
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# verify redirect_uri doesn't change between /authorize and /tokens
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# see https://datatracker.ietf.org/doc/html/rfc6749#section-10.6
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if auth_code.redirect_uri_provided_explicitly:
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authorize_request_redirect_uri = auth_code.redirect_uri
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else:
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authorize_request_redirect_uri = None
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if token_request.redirect_uri != authorize_request_redirect_uri:
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return self.response(
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TokenErrorResponse(
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error="invalid_request",
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error_description=(
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"redirect_uri did not match the one "
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"used when creating auth code"
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),
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)
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)
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# Verify PKCE code verifier
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sha256 = hashlib.sha256(token_request.code_verifier.encode()).digest()
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hashed_code_verifier = (
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base64.urlsafe_b64encode(sha256).decode().rstrip("=")
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)
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if hashed_code_verifier != auth_code.code_challenge:
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# see https://datatracker.ietf.org/doc/html/rfc7636#section-4.6
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return self.response(
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TokenErrorResponse(
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error="invalid_grant",
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error_description="incorrect code_verifier",
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)
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)
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try:
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# Exchange authorization code for tokens
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tokens = await self.provider.exchange_authorization_code(
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client_info, auth_code
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)
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except TokenError as e:
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return self.response(
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TokenErrorResponse(
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error=e.error,
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error_description=e.error_description,
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)
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)
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case RefreshTokenRequest():
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refresh_token = await self.provider.load_refresh_token(
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client_info, token_request.refresh_token
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)
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if (
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refresh_token is None
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or refresh_token.client_id != token_request.client_id
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):
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# if token belongs to different client, pretend it doesn't exist
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return self.response(
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TokenErrorResponse(
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error="invalid_grant",
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error_description="refresh token does not exist",
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)
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)
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if refresh_token.expires_at and refresh_token.expires_at < time.time():
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# if the refresh token has expired, pretend it doesn't exist
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return self.response(
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TokenErrorResponse(
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error="invalid_grant",
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error_description="refresh token has expired",
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)
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)
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# Parse scopes if provided
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scopes = (
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token_request.scope.split(" ")
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if token_request.scope
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else refresh_token.scopes
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)
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for scope in scopes:
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if scope not in refresh_token.scopes:
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return self.response(
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TokenErrorResponse(
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error="invalid_scope",
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error_description=(
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f"cannot request scope `{scope}` "
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"not provided by refresh token"
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),
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)
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)
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try:
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# Exchange refresh token for new tokens
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tokens = await self.provider.exchange_refresh_token(
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client_info, refresh_token, scopes
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)
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except TokenError as e:
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return self.response(
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TokenErrorResponse(
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error=e.error,
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error_description=e.error_description,
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)
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)
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return self.response(TokenSuccessResponse(root=tokens))
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