MCP server separation into Authorization Server (AS) and Resource Server (RS) roles per spec PR #338 (#982)
Co-authored-by: Paul Carleton <paulc@anthropic.com>
This commit is contained in:
Inna Harper
GitHub
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1 changed files with 1851 additions and 1603 deletions
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"""
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Shared GitHub OAuth provider for MCP servers.
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This module contains the common GitHub OAuth functionality used by both
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the standalone authorization server and the legacy combined server.
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NOTE: this is a simplified example for demonstration purposes.
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This is not a production-ready implementation.
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"""
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import logging
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import secrets
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import time
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from typing import Any
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from pydantic import AnyHttpUrl
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from pydantic_settings import BaseSettings, SettingsConfigDict
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from starlette.exceptions import HTTPException
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from mcp.server.auth.provider import (
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AccessToken,
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AuthorizationCode,
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AuthorizationParams,
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OAuthAuthorizationServerProvider,
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RefreshToken,
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construct_redirect_uri,
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)
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from mcp.shared._httpx_utils import create_mcp_http_client
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from mcp.shared.auth import OAuthClientInformationFull, OAuthToken
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logger = logging.getLogger(__name__)
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class GitHubOAuthSettings(BaseSettings):
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"""Common GitHub OAuth settings."""
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model_config = SettingsConfigDict(env_prefix="MCP_")
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# GitHub OAuth settings - MUST be provided via environment variables
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github_client_id: str | None = None
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github_client_secret: str | None = None
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# GitHub OAuth URLs
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github_auth_url: str = "https://github.com/login/oauth/authorize"
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github_token_url: str = "https://github.com/login/oauth/access_token"
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mcp_scope: str = "user"
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github_scope: str = "read:user"
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class GitHubOAuthProvider(OAuthAuthorizationServerProvider):
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"""
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OAuth provider that uses GitHub as the identity provider.
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This provider handles the OAuth flow by:
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1. Redirecting users to GitHub for authentication
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2. Exchanging GitHub tokens for MCP tokens
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3. Maintaining token mappings for API access
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"""
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def __init__(self, settings: GitHubOAuthSettings, github_callback_url: str):
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self.settings = settings
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self.github_callback_url = github_callback_url
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self.clients: dict[str, OAuthClientInformationFull] = {}
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self.auth_codes: dict[str, AuthorizationCode] = {}
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self.tokens: dict[str, AccessToken] = {}
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self.state_mapping: dict[str, dict[str, str]] = {}
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# Maps MCP tokens to GitHub tokens
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self.token_mapping: dict[str, str] = {}
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async def get_client(self, client_id: str) -> OAuthClientInformationFull | None:
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"""Get OAuth client information."""
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return self.clients.get(client_id)
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async def register_client(self, client_info: OAuthClientInformationFull):
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"""Register a new OAuth client."""
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self.clients[client_info.client_id] = client_info
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async def authorize(self, client: OAuthClientInformationFull, params: AuthorizationParams) -> str:
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"""Generate an authorization URL for GitHub OAuth flow."""
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state = params.state or secrets.token_hex(16)
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# Store state mapping for callback
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self.state_mapping[state] = {
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"redirect_uri": str(params.redirect_uri),
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"code_challenge": params.code_challenge,
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"redirect_uri_provided_explicitly": str(params.redirect_uri_provided_explicitly),
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"client_id": client.client_id,
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}
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# Build GitHub authorization URL
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auth_url = (
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f"{self.settings.github_auth_url}"
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f"?client_id={self.settings.github_client_id}"
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f"&redirect_uri={self.github_callback_url}"
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f"&scope={self.settings.github_scope}"
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f"&state={state}"
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)
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return auth_url
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async def handle_github_callback(self, code: str, state: str) -> str:
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"""Handle GitHub OAuth callback and return redirect URI."""
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state_data = self.state_mapping.get(state)
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if not state_data:
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raise HTTPException(400, "Invalid state parameter")
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redirect_uri = state_data["redirect_uri"]
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code_challenge = state_data["code_challenge"]
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redirect_uri_provided_explicitly = state_data["redirect_uri_provided_explicitly"] == "True"
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client_id = state_data["client_id"]
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# Exchange code for token with GitHub
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async with create_mcp_http_client() as client:
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response = await client.post(
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self.settings.github_token_url,
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data={
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"client_id": self.settings.github_client_id,
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"client_secret": self.settings.github_client_secret,
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"code": code,
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"redirect_uri": self.github_callback_url,
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},
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headers={"Accept": "application/json"},
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)
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if response.status_code != 200:
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raise HTTPException(400, "Failed to exchange code for token")
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data = response.json()
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if "error" in data:
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raise HTTPException(400, data.get("error_description", data["error"]))
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github_token = data["access_token"]
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# Create MCP authorization code
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new_code = f"mcp_{secrets.token_hex(16)}"
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auth_code = AuthorizationCode(
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code=new_code,
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client_id=client_id,
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redirect_uri=AnyHttpUrl(redirect_uri),
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redirect_uri_provided_explicitly=redirect_uri_provided_explicitly,
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expires_at=time.time() + 300,
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scopes=[self.settings.mcp_scope],
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code_challenge=code_challenge,
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)
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self.auth_codes[new_code] = auth_code
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# Store GitHub token with MCP client_id
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self.tokens[github_token] = AccessToken(
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token=github_token,
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client_id=client_id,
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scopes=[self.settings.github_scope],
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expires_at=None,
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)
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del self.state_mapping[state]
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return construct_redirect_uri(redirect_uri, code=new_code, state=state)
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async def load_authorization_code(
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self, client: OAuthClientInformationFull, authorization_code: str
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) -> AuthorizationCode | None:
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"""Load an authorization code."""
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return self.auth_codes.get(authorization_code)
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async def exchange_authorization_code(
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self, client: OAuthClientInformationFull, authorization_code: AuthorizationCode
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) -> OAuthToken:
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"""Exchange authorization code for tokens."""
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if authorization_code.code not in self.auth_codes:
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raise ValueError("Invalid authorization code")
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# Generate MCP access token
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mcp_token = f"mcp_{secrets.token_hex(32)}"
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# Store MCP token
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self.tokens[mcp_token] = AccessToken(
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token=mcp_token,
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client_id=client.client_id,
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scopes=authorization_code.scopes,
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expires_at=int(time.time()) + 3600,
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)
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# Find GitHub token for this client
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github_token = next(
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(
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token
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for token, data in self.tokens.items()
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if (token.startswith("ghu_") or token.startswith("gho_")) and data.client_id == client.client_id
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),
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None,
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)
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# Store mapping between MCP token and GitHub token
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if github_token:
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self.token_mapping[mcp_token] = github_token
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del self.auth_codes[authorization_code.code]
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return OAuthToken(
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access_token=mcp_token,
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token_type="Bearer",
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expires_in=3600,
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scope=" ".join(authorization_code.scopes),
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)
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async def load_access_token(self, token: str) -> AccessToken | None:
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"""Load and validate an access token."""
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access_token = self.tokens.get(token)
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if not access_token:
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return None
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# Check if expired
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if access_token.expires_at and access_token.expires_at < time.time():
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del self.tokens[token]
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return None
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return access_token
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async def load_refresh_token(self, client: OAuthClientInformationFull, refresh_token: str) -> RefreshToken | None:
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"""Load a refresh token - not supported in this example."""
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return None
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async def exchange_refresh_token(
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self,
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client: OAuthClientInformationFull,
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refresh_token: RefreshToken,
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scopes: list[str],
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) -> OAuthToken:
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"""Exchange refresh token - not supported in this example."""
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raise NotImplementedError("Refresh tokens not supported")
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async def revoke_token(self, token: str, token_type_hint: str | None = None) -> None:
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"""Revoke a token."""
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if token in self.tokens:
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del self.tokens[token]
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async def get_github_user_info(self, mcp_token: str) -> dict[str, Any]:
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"""Get GitHub user info using MCP token."""
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github_token = self.token_mapping.get(mcp_token)
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if not github_token:
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raise ValueError("No GitHub token found for MCP token")
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async with create_mcp_http_client() as client:
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response = await client.get(
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"https://api.github.com/user",
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headers={
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"Authorization": f"Bearer {github_token}",
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"Accept": "application/vnd.github.v3+json",
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},
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)
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if response.status_code != 200:
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raise ValueError(f"GitHub API error: {response.status_code}")
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return response.json()
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