300 lines
10 KiB
Python
300 lines
10 KiB
Python
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# Copyright 2023-present MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""MONGODB-OIDC Authentication helpers."""
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import os
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import threading
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from dataclasses import dataclass, field
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from datetime import datetime, timedelta, timezone
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from typing import Callable, Dict, List, Optional
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import bson
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from bson.binary import Binary
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from bson.son import SON
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from pymongo.errors import ConfigurationError, OperationFailure
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from pymongo.helpers import _REAUTHENTICATION_REQUIRED_CODE
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@dataclass
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class _OIDCProperties:
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request_token_callback: Optional[Callable[..., Dict]]
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refresh_token_callback: Optional[Callable[..., Dict]]
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provider_name: Optional[str]
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allowed_hosts: List[str]
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"""Mechanism properties for MONGODB-OIDC authentication."""
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TOKEN_BUFFER_MINUTES = 5
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CALLBACK_TIMEOUT_SECONDS = 5 * 60
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CACHE_TIMEOUT_MINUTES = 60 * 5
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CALLBACK_VERSION = 0
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_CACHE: Dict[str, "_OIDCAuthenticator"] = {}
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def _get_authenticator(credentials, address):
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# Clear out old items in the cache.
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now_utc = datetime.now(timezone.utc)
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to_remove = []
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for key, value in _CACHE.items():
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if value.cache_exp_utc is not None and value.cache_exp_utc < now_utc:
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to_remove.append(key)
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for key in to_remove:
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del _CACHE[key]
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# Extract values.
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principal_name = credentials.username
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properties = credentials.mechanism_properties
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request_cb = properties.request_token_callback
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refresh_cb = properties.refresh_token_callback
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# Validate that the address is allowed.
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if not properties.provider_name:
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found = False
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allowed_hosts = properties.allowed_hosts
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for patt in allowed_hosts:
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if patt == address[0]:
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found = True
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elif patt.startswith("*.") and address[0].endswith(patt[1:]):
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found = True
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if not found:
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raise ConfigurationError(
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f"Refusing to connect to {address[0]}, which is not in authOIDCAllowedHosts: {allowed_hosts}"
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)
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# Get or create the cache item.
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cache_key = f"{principal_name}{address[0]}{address[1]}{id(request_cb)}{id(refresh_cb)}"
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_CACHE.setdefault(cache_key, _OIDCAuthenticator(username=principal_name, properties=properties))
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return _CACHE[cache_key]
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def _get_cache_exp():
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return datetime.now(timezone.utc) + timedelta(minutes=CACHE_TIMEOUT_MINUTES)
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@dataclass
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class _OIDCAuthenticator:
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username: str
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properties: _OIDCProperties
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idp_info: Optional[Dict] = field(default=None)
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idp_resp: Optional[Dict] = field(default=None)
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reauth_gen_id: int = field(default=0)
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idp_info_gen_id: int = field(default=0)
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token_gen_id: int = field(default=0)
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token_exp_utc: Optional[datetime] = field(default=None)
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cache_exp_utc: datetime = field(default_factory=_get_cache_exp)
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lock: threading.Lock = field(default_factory=threading.Lock)
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def get_current_token(self, use_callbacks=True):
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properties = self.properties
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request_cb = properties.request_token_callback
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refresh_cb = properties.refresh_token_callback
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if not use_callbacks:
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request_cb = None
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refresh_cb = None
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current_valid_token = False
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if self.token_exp_utc is not None:
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now_utc = datetime.now(timezone.utc)
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exp_utc = self.token_exp_utc
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buffer_seconds = TOKEN_BUFFER_MINUTES * 60
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if (exp_utc - now_utc).total_seconds() >= buffer_seconds:
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current_valid_token = True
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timeout = CALLBACK_TIMEOUT_SECONDS
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if not use_callbacks and not current_valid_token:
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return None
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if not current_valid_token and request_cb is not None:
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prev_token = self.idp_resp and self.idp_resp["access_token"]
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with self.lock:
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# See if the token was changed while we were waiting for the
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# lock.
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new_token = self.idp_resp and self.idp_resp["access_token"]
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if new_token != prev_token:
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return new_token
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refresh_token = self.idp_resp and self.idp_resp.get("refresh_token")
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refresh_token = refresh_token or ""
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context = {
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"timeout_seconds": timeout,
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"version": CALLBACK_VERSION,
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"refresh_token": refresh_token,
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}
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if self.idp_resp is None or refresh_cb is None:
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self.idp_resp = request_cb(self.idp_info, context)
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elif request_cb is not None:
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self.idp_resp = refresh_cb(self.idp_info, context)
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cache_exp_utc = datetime.now(timezone.utc) + timedelta(
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minutes=CACHE_TIMEOUT_MINUTES
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)
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self.cache_exp_utc = cache_exp_utc
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self.token_gen_id += 1
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token_result = self.idp_resp
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# Validate callback return value.
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if not isinstance(token_result, dict):
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raise ValueError("OIDC callback returned invalid result")
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if "access_token" not in token_result:
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raise ValueError("OIDC callback did not return an access_token")
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expected = ["access_token", "expires_in_seconds", "refesh_token"]
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for key in token_result:
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if key not in expected:
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raise ValueError(f'Unexpected field in callback result "{key}"')
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token = token_result["access_token"]
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if "expires_in_seconds" in token_result:
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expires_in = int(token_result["expires_in_seconds"])
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buffer_seconds = TOKEN_BUFFER_MINUTES * 60
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if expires_in >= buffer_seconds:
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now_utc = datetime.now(timezone.utc)
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exp_utc = now_utc + timedelta(seconds=expires_in)
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self.token_exp_utc = exp_utc
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return token
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def auth_start_cmd(self, use_callbacks=True):
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properties = self.properties
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# Handle aws provider credentials.
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if properties.provider_name == "aws":
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aws_identity_file = os.environ["AWS_WEB_IDENTITY_TOKEN_FILE"]
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with open(aws_identity_file) as fid:
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token = fid.read().strip()
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payload = {"jwt": token}
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cmd = SON(
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[
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("saslStart", 1),
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("mechanism", "MONGODB-OIDC"),
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("payload", Binary(bson.encode(payload))),
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]
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)
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return cmd
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principal_name = self.username
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if self.idp_info is not None:
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self.cache_exp_utc = datetime.now(timezone.utc) + timedelta(
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minutes=CACHE_TIMEOUT_MINUTES
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)
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if self.idp_info is None:
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self.cache_exp_utc = _get_cache_exp()
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if self.idp_info is None:
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# Send the SASL start with the optional principal name.
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payload = {}
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if principal_name:
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payload["n"] = principal_name
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cmd = SON(
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[
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("saslStart", 1),
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("mechanism", "MONGODB-OIDC"),
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("payload", Binary(bson.encode(payload))),
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("autoAuthorize", 1),
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]
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)
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return cmd
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token = self.get_current_token(use_callbacks)
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if not token:
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return None
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bin_payload = Binary(bson.encode({"jwt": token}))
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return SON(
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[
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("saslStart", 1),
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("mechanism", "MONGODB-OIDC"),
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("payload", bin_payload),
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]
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)
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def clear(self):
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self.idp_info = None
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self.idp_resp = None
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self.token_exp_utc = None
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def run_command(self, sock_info, cmd):
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try:
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return sock_info.command("$external", cmd, no_reauth=True)
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except OperationFailure as exc:
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self.clear()
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if exc.code == _REAUTHENTICATION_REQUIRED_CODE:
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if "jwt" in bson.decode(cmd["payload"]): # type:ignore[attr-defined]
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if self.idp_info_gen_id > self.reauth_gen_id:
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raise
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return self.authenticate(sock_info, reauthenticate=True)
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raise
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def authenticate(self, sock_info, reauthenticate=False):
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if reauthenticate:
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prev_id = getattr(sock_info, "oidc_token_gen_id", None)
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# Check if we've already changed tokens.
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if prev_id == self.token_gen_id:
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self.reauth_gen_id = self.idp_info_gen_id
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self.token_exp_utc = None
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if not self.properties.refresh_token_callback:
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self.clear()
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ctx = sock_info.auth_ctx
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cmd = None
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if ctx and ctx.speculate_succeeded():
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resp = ctx.speculative_authenticate
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else:
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cmd = self.auth_start_cmd()
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resp = self.run_command(sock_info, cmd)
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if resp["done"]:
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sock_info.oidc_token_gen_id = self.token_gen_id
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return None
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server_resp: Dict = bson.decode(resp["payload"])
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if "issuer" in server_resp:
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self.idp_info = server_resp
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self.idp_info_gen_id += 1
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conversation_id = resp["conversationId"]
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token = self.get_current_token()
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sock_info.oidc_token_gen_id = self.token_gen_id
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bin_payload = Binary(bson.encode({"jwt": token}))
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cmd = SON(
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[
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("saslContinue", 1),
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("conversationId", conversation_id),
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("payload", bin_payload),
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]
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)
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resp = self.run_command(sock_info, cmd)
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if not resp["done"]:
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self.clear()
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raise OperationFailure("SASL conversation failed to complete.")
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return resp
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def _authenticate_oidc(credentials, sock_info, reauthenticate):
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"""Authenticate using MONGODB-OIDC."""
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authenticator = _get_authenticator(credentials, sock_info.address)
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return authenticator.authenticate(sock_info, reauthenticate=reauthenticate)
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