359 lines
21 KiB
Python
359 lines
21 KiB
Python
"""Project-local OAuth provider for the MCP SDK: consent, PKCE grants and rotating tokens.
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The SDK validates protocol requests, redirects, client credentials and S256 PKCE.
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This module stores grants and authenticates the project owner on a separate consent page.
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It implements a shared project access code, not a multi-user identity service.
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"""
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from __future__ import annotations
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from contextlib import contextmanager
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import hashlib
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import hmac
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from html import escape
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import json
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import os
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from pathlib import Path
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import re
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import secrets
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import sqlite3
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import time
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from urllib.parse import parse_qs, urlsplit
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from mcp.server.auth.provider import (
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AccessToken, AuthorizationCode, AuthorizationParams, AuthorizeError,
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RefreshToken, RegistrationError, TokenError, construct_redirect_uri,
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)
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from mcp.shared.auth import OAuthClientInformationFull, OAuthToken
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from starlette.responses import HTMLResponse, JSONResponse, RedirectResponse
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SCOPE = 'zpwiki:read'
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SCOPES = [SCOPE, 'offline_access']
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CALLBACKS = {'https://claude.ai/api/mcp/auth_callback'}
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COOKIE = '__Host-zp-oauth'
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PENDING_TTL, CODE_TTL, ACCESS_TTL, REFRESH_TTL = 600, 120, 3600, 30 * 86400
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def digest(value: str) -> str:
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return hashlib.sha256(value.encode()).hexdigest()
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class Store:
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def __init__(self, path: Path, namespace: str):
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self.path, self.namespace = path, namespace
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path.parent.mkdir(parents=True, exist_ok=True, mode=0o700)
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if not path.exists():
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fd = os.open(path, os.O_CREAT | os.O_EXCL | os.O_WRONLY, 0o600)
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os.close(fd)
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path.chmod(0o600)
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with self.transaction() as conn:
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conn.execute('''CREATE TABLE IF NOT EXISTS records (
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namespace TEXT NOT NULL, kind TEXT NOT NULL, key TEXT NOT NULL,
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body TEXT NOT NULL, expires REAL NOT NULL, family TEXT NOT NULL DEFAULT '',
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PRIMARY KEY(namespace,kind,key))''')
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conn.execute('CREATE INDEX IF NOT EXISTS oauth_family ON records(namespace,family)')
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conn.execute('CREATE INDEX IF NOT EXISTS oauth_expiry ON records(expires)')
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@contextmanager
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def transaction(self):
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conn = sqlite3.connect(self.path, timeout=5)
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try:
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conn.execute('BEGIN IMMEDIATE')
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yield conn
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conn.commit()
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except BaseException:
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conn.rollback()
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raise
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finally:
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conn.close()
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def get(self, conn, kind, key):
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row = conn.execute('SELECT body FROM records WHERE namespace=? AND kind=? AND key=? AND expires>?',
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(self.namespace, kind, key, time.time())).fetchone()
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return json.loads(row[0]) if row else None
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def put(self, conn, kind, key, body, expires, family=''):
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conn.execute('INSERT OR REPLACE INTO records VALUES (?,?,?,?,?,?)',
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(self.namespace, kind, key, json.dumps(body), expires, family))
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def delete(self, conn, kind, key):
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conn.execute('DELETE FROM records WHERE namespace=? AND kind=? AND key=?',
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(self.namespace, kind, key))
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def capacity(self, conn, kind, maximum):
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conn.execute('DELETE FROM records WHERE expires<=?', (time.time(),))
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return conn.execute('SELECT count(*) FROM records WHERE namespace=? AND kind=?',
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(self.namespace, kind)).fetchone()[0] < maximum
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def revoke_family(self, conn, family):
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conn.execute('DELETE FROM records WHERE namespace=? AND family=?', (self.namespace, family))
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class OAuthProvider:
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def __init__(self, resource: str, static_token: str, password: str, database: Path):
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if (len(password) < 32 or not password.isascii() or any(c.isspace() for c in password)
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or hmac.compare_digest(password, static_token)):
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raise ValueError('Configure a separate ZP_MCP_LOGIN_PASSWORD with at least 32 characters')
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self.resource = resource
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url = urlsplit(resource)
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self.origin = url.scheme + '://' + url.netloc
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self.static_token, self.password_hash = static_token, digest(password)
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# A changed public URL or rotated owner credential invalidates previous sessions.
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self.store = Store(database, digest(resource + '\0' + static_token + '\0' + password))
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async def get_client(self, client_id):
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'client', client_id)
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return OAuthClientInformationFull.model_validate(value) if value else None
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async def register_client(self, client_info):
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redirects = [str(uri) for uri in client_info.redirect_uris or []]
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if (not redirects or len(redirects) > 4 or any(uri not in CALLBACKS for uri in redirects)
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or client_info.token_endpoint_auth_method not in {'none', 'client_secret_post', 'client_secret_basic'}
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or set(client_info.grant_types) != {'authorization_code', 'refresh_token'}
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or client_info.response_types != ['code']
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or not set((client_info.scope or '').split()) <= set(SCOPES)):
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raise RegistrationError('invalid_client_metadata', 'Only the documented Claude web callback and code flow are supported')
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with self.store.transaction() as conn:
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if not self.store.capacity(conn, 'client', 1024):
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raise RegistrationError('invalid_client_metadata', 'Client registration capacity reached')
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self.store.put(conn, 'client', client_info.client_id, client_info.model_dump(mode='json'),
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time.time() + 90 * 86400)
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async def authorize(self, client, params: AuthorizationParams):
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if params.resource not in {None, self.resource}:
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raise AuthorizeError('invalid_request', 'The requested resource does not match this MCP server')
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scopes = params.scopes or (client.scope or SCOPE).split()
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if SCOPE not in scopes or not set(scopes) <= set(SCOPES):
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raise AuthorizeError('invalid_scope', 'The read scope is required')
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if not re.fullmatch(r'[A-Za-z0-9_-]{43}', params.code_challenge):
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raise AuthorizeError('invalid_request', 'S256 PKCE is required')
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request_id = secrets.token_urlsafe(32)
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value = {'client_id': client.client_id, 'client_name': (client.client_name or 'Claude')[:100],
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'params': params.model_copy(update={'scopes': scopes, 'resource': self.resource}).model_dump(mode='json'),
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'attempts': 0, 'expires': time.time() + PENDING_TTL}
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with self.store.transaction() as conn:
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if not self.store.capacity(conn, 'pending', 1024):
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raise AuthorizeError('temporarily_unavailable', 'Please retry later')
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self.store.put(conn, 'pending', digest(request_id), value, value['expires'])
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return self.origin + '/oauth/login?request=' + request_id
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async def load_authorization_code(self, client, authorization_code):
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'code', digest(authorization_code))
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if not value or value['client_id'] != client.client_id:
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return None
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return AuthorizationCode(code=authorization_code, **value)
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def _issue(self, conn, client_id, scopes, family, refresh_expiry=None):
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now = int(time.time())
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access = secrets.token_urlsafe(48)
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refresh_expiry = refresh_expiry or now + REFRESH_TTL
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expiry = min(now + ACCESS_TTL, refresh_expiry)
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common = {'client_id': client_id, 'scopes': scopes, 'resource': self.resource, 'subject': 'project-user'}
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self.store.put(conn, 'access', digest(access), {**common, 'expires_at': expiry}, expiry, family)
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refresh = None
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if 'offline_access' in scopes:
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refresh = secrets.token_urlsafe(48)
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self.store.put(conn, 'refresh', digest(refresh),
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{**common, 'expires_at': refresh_expiry, 'family': family, 'used': False}, refresh_expiry, family)
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return OAuthToken(access_token=access, expires_in=expiry-now, refresh_token=refresh, scope=' '.join(scopes))
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async def exchange_authorization_code(self, client, authorization_code):
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'code', digest(authorization_code.code))
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if not value or value['client_id'] != client.client_id:
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raise TokenError('invalid_grant', 'The code has expired or was already used')
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self.store.delete(conn, 'code', digest(authorization_code.code))
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return self._issue(conn, client.client_id, value['scopes'], secrets.token_hex(24))
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async def load_refresh_token(self, client, refresh_token):
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'refresh', digest(refresh_token))
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if not value or value['client_id'] != client.client_id:
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return None
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return RefreshToken(token=refresh_token, **{k:v for k,v in value.items() if k not in {'family','used'}})
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async def exchange_refresh_token(self, client, refresh_token, scopes):
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replay = False
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'refresh', digest(refresh_token.token))
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if not value or value['client_id'] != client.client_id:
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raise TokenError('invalid_grant', 'Invalid refresh token')
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if value['used']:
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self.store.revoke_family(conn, value['family'])
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replay = True
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else:
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if SCOPE not in scopes or not set(scopes) <= set(value['scopes']):
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raise TokenError('invalid_scope', 'Requested scopes exceed the grant')
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value['used'] = True
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self.store.put(conn, 'refresh', digest(refresh_token.token), value, value['expires_at'], value['family'])
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# Rotate both credentials; retire old access tokens in the same family.
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conn.execute('DELETE FROM records WHERE namespace=? AND kind=? AND family=?',
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(self.store.namespace, 'access', value['family']))
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issued = self._issue(conn, client.client_id, scopes, value['family'], value['expires_at'])
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if replay:
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raise TokenError('invalid_grant', 'Refresh token reuse revoked this grant')
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return issued
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async def load_access_token(self, token):
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if hmac.compare_digest(token.encode(), self.static_token.encode()):
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return AccessToken(token=token, client_id='local-static', scopes=[SCOPE], resource=self.resource)
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'access', digest(token))
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return AccessToken(token=token, **value) if value else None
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async def revoke_token(self, token):
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with self.store.transaction() as conn:
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value = self.store.get(conn, 'access', digest(token.token)) or self.store.get(conn, 'refresh', digest(token.token))
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row = conn.execute('SELECT family FROM records WHERE namespace=? AND key=? AND kind IN (?,?)',
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(self.store.namespace, digest(token.token), 'access', 'refresh')).fetchone()
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if value and row:
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self.store.revoke_family(conn, row[0])
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def _form(self, request_id, pending, csrf, message='', status=200):
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target = escape(urlsplit(pending['params']['redirect_uri']).hostname or '')
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name = escape(pending['client_name'])
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document = f'''<!doctype html><html lang="sk"><meta charset="utf-8">
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<meta name="viewport" content="width=device-width,initial-scale=1"><title>Prihlásenie — ZP Agent</title>
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<style>body{{font:17px system-ui;max-width:520px;margin:8vh auto;padding:24px;line-height:1.5;background:#f5f5f5;color:#222}}
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form{{background:white;padding:24px;border-radius:12px}}input,button{{box-sizing:border-box;width:100%;padding:12px;margin:8px 0;font:inherit}}
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.error{{color:#a00}}small{{display:block}}</style>
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<h1>Pripojiť ZP Agenta</h1><p>Aplikácia <strong>{name}</strong> žiada prístup k vyhľadávaniu RAG a GraphRAG.</p>
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<p>Po potvrdení sa vrátiš na <strong>{target}</strong>.</p><form method="post" action="/oauth/login">
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<input type="hidden" name="request" value="{escape(request_id)}"><input type="hidden" name="csrf" value="{escape(csrf)}">
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<label for="password">Prístupový kód ZP Agenta</label><input id="password" name="password" type="password" autocomplete="current-password" required autofocus>
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<small>Kód ti poskytne správca ZP Agenta. Nezadávaj sem heslo svojho účtu Claude.</small>
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<p class="error">{escape(message)}</p><button name="action" value="allow">Prihlásiť a povoliť prístup</button>
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<button name="action" value="deny" formnovalidate>Zrušiť</button></form></html>'''
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return HTMLResponse(document, status_code=status)
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async def login(self, request):
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if request.method == 'GET':
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request_id = request.query_params.get('request', '')
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with self.store.transaction() as conn:
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pending = self.store.get(conn, 'pending', digest(request_id))
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if not pending:
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return HTMLResponse('Prihlásenie vypršalo. Začni pripojenie znova v Claude.', status_code=400)
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csrf = secrets.token_urlsafe(32)
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pending['csrf'] = digest(csrf)
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self.store.put(conn, 'pending', digest(request_id), pending, pending['expires'])
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response = self._form(request_id, pending, csrf)
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response.set_cookie(COOKIE, csrf, max_age=PENDING_TTL, secure=True, httponly=True, samesite='lax', path='/')
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return response
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if request.headers.get('origin') not in {None, self.origin}:
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return JSONResponse({'error':'invalid_origin'}, status_code=403)
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if request.headers.get('content-type','').split(';')[0] != 'application/x-www-form-urlencoded':
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return JSONResponse({'error':'invalid_request'}, status_code=415)
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form = parse_qs((await request.body()).decode('utf-8', errors='replace'), keep_blank_values=True)
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if any(len(values) != 1 for values in form.values()):
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return JSONResponse({'error':'invalid_request'}, status_code=400)
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get = lambda name: form.get(name, [''])[0]
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request_id, csrf = get('request'), get('csrf')
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with self.store.transaction() as conn:
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pending = self.store.get(conn, 'pending', digest(request_id))
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if (not pending or not csrf or not request.cookies.get(COOKIE)
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or not hmac.compare_digest(csrf.encode(), request.cookies[COOKIE].encode())
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or not hmac.compare_digest(digest(csrf), pending.get('csrf', ''))):
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return JSONResponse({'error':'invalid_csrf_or_expired_login'}, status_code=403)
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if get('action') == 'deny':
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self.store.delete(conn, 'pending', digest(request_id))
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response = RedirectResponse(construct_redirect_uri(pending['params']['redirect_uri'],
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error='access_denied', state=pending['params'].get('state')), status_code=303)
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response.delete_cookie(COOKIE, secure=True, httponly=True, samesite='lax')
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return response
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bucket = str(int(time.time()) // 60)
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rate = self.store.get(conn, 'login_rate', bucket) or {'count': 0}
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rate['count'] += 1
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self.store.put(conn, 'login_rate', bucket, rate, time.time()+120)
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if rate['count'] > 30 or pending['attempts'] >= 5:
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return self._form(request_id, pending, csrf, 'Príliš veľa pokusov. Skús to neskôr.', 429)
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if get('action') != 'allow' or not hmac.compare_digest(digest(get('password')), self.password_hash):
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pending['attempts'] += 1
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self.store.put(conn, 'pending', digest(request_id), pending, pending['expires'])
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return self._form(request_id, pending, csrf, 'Nesprávny prístupový kód.', 401)
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code = secrets.token_urlsafe(32)
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params = pending['params']
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value = {k:params[k] for k in ['scopes','code_challenge','redirect_uri',
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'redirect_uri_provided_explicitly','resource']}
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value.update(client_id=pending['client_id'], expires_at=time.time()+CODE_TTL, subject='project-user')
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self.store.put(conn, 'code', digest(code), value, value['expires_at'])
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self.store.delete(conn, 'pending', digest(request_id))
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response = RedirectResponse(construct_redirect_uri(params['redirect_uri'], code=code, state=params.get('state')), status_code=303)
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response.delete_cookie(COOKIE, secure=True, httponly=True, samesite='lax')
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return response
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class OAuthBoundary:
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"""Bound auth request bodies, enforce resource binding and harden the consent page."""
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def __init__(self, app, provider):
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self.app, self.provider = app, provider
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async def __call__(self, scope, receive, send):
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if scope['type'] != 'http':
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return await self.app(scope, receive, send)
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headers = dict(scope['headers'])
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public_host = urlsplit(self.provider.origin).netloc
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host = headers.get(b'host', b'').decode('latin1')
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if host != public_host and not re.fullmatch(r'(?:127\.0\.0\.1|localhost)(?::\d+)?', host):
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return await JSONResponse({'error':'invalid_host'}, status_code=421)(scope, receive, send)
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path = scope['path']
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if scope['method'] == 'POST' and path in {'/token','/register','/authorize','/revoke','/oauth/login'}:
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body = bytearray()
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while True:
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message = await receive()
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if message['type'] == 'http.disconnect':
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return
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body.extend(message.get('body', b''))
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if len(body) > 16384:
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return await JSONResponse({'error':'request_too_large'}, status_code=413)(scope, receive, send)
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if not message.get('more_body'):
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break
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if path in {'/token', '/revoke'}:
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if headers.get(b'content-type',b'').split(b';')[0] != b'application/x-www-form-urlencoded':
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return await JSONResponse({'error':'invalid_request'}, status_code=415)(scope, receive, send)
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fields = parse_qs(body.decode('utf-8', errors='replace'), keep_blank_values=True)
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if any(len(v)!=1 for v in fields.values()) or fields.get('resource',[self.provider.resource]) != [self.provider.resource]:
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return await JSONResponse({'error':'invalid_request'}, status_code=400)(scope, receive, send)
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# SDK 1.x models an optional revocation secret as a required nullable field.
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# Public clients have no secret; normalize that omission before its parser.
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if path == '/revoke' and 'client_secret' not in fields:
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body.extend(b'&client_secret=')
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if path == '/register':
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try:
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value = json.loads(body)
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if not isinstance(value, dict):
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raise ValueError()
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except (ValueError, UnicodeError):
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return await JSONResponse({'error':'invalid_client_metadata'}, status_code=400)(scope, receive, send)
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original_receive = receive
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sent = False
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async def replay():
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nonlocal sent
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if not sent:
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sent = True
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return {'type':'http.request','body':bytes(body),'more_body':False}
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return await original_receive()
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receive = replay
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async def secured(message):
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if message['type'] == 'http.response.start':
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existing = list(message.get('headers', []))
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names = {k.lower() for k,v in existing}
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defaults = {b'cache-control':b'no-store', b'pragma':b'no-cache', b'referrer-policy':b'no-referrer',
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b'x-content-type-options':b'nosniff', b'x-frame-options':b'DENY'}
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if path == '/oauth/login':
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# no-referrer makes native form POSTs send Origin: null (Fetch).
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# Keep the real origin for this same-origin form while suppressing
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# the referrer on the redirect to Claude. CSRF checks stay strict.
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defaults[b'referrer-policy'] = b'same-origin'
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# Chromium applies form-action to POST redirects too. Permit only
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# the same fixed callbacks accepted during OAuth registration.
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callbacks = ' '.join(sorted(CALLBACKS))
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defaults[b'content-security-policy'] = (
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"default-src 'none'; style-src 'unsafe-inline'; form-action 'self' "
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+ callbacks + "; frame-ancestors 'none'; base-uri 'none'").encode()
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message = {**message,'headers':existing+[(k,v) for k,v in defaults.items() if k not in names]}
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await send(message)
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return await self.app(scope, receive, secured)
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