Files
hermes-agent/tools/mcp_oauth_manager.py
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529 lines
27 KiB
Python

#!/usr/bin/env python3
"""Central manager for per-server MCP OAuth state (one instance per process).
Holds per-server provider instances and coordinates cross-process token reload (mtime-based
disk watch, so tokens refreshed by cron/another CLI are picked up without a restart), 401
deduplication (N concurrent tool calls hitting 401 with the same access_token trigger one
recovery attempt) and reconnect signalling (``MCPServerTask`` in ``mcp_tool.py`` drives the
reconnect; the manager decides when it is warranted).
This module is the ONLY place that instantiates the SDK's ``OAuthClientProvider`` for runtime
use; other code paths go through ``get_manager()``. We lean on the SDK's lazy refresh rather
than refreshing before every op: one ``stat()`` per tool call is cheaper than an await +
refresh round-trip.
"""
from __future__ import annotations
import asyncio
import logging
import re
import threading
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Optional
from tools.mcp_oauth_provider import HermesProviderMixin
logger = logging.getLogger(__name__)
def _same_endpoint(a: str, b: str) -> bool:
"""True if two URLs target the same endpoint: scheme, host (case-insensitive) and path,
ignoring query/fragment. Confirms a rejected response actually came from the OAuth token
endpoint before we act on an ``invalid_client`` body."""
from urllib.parse import urlsplit
try:
pa, pb = urlsplit(a), urlsplit(b)
except ValueError: # pragma: no cover — malformed URL
return False
return pa.scheme == pb.scheme and pa.netloc.lower() == pb.netloc.lower() and pa.path.rstrip("/") == pb.path.rstrip("/")
@dataclass
class _ProviderEntry:
"""Per-server OAuth state. ``last_mtime_ns`` is the last-seen tokens-file mtime (0 = never
read) for external-refresh detection; ``lock`` binds to whichever asyncio loop first awaits
it (the MCP event loop); ``pending_401`` dedupes thundering-herd 401s by failed access_token."""
server_url: str
oauth_config: Optional[dict]
provider: Optional[Any] = None
last_mtime_ns: int = 0
lock: asyncio.Lock = field(default_factory=asyncio.Lock)
pending_401: dict[str, "asyncio.Future[bool]"] = field(default_factory=dict)
# -- HermesMCPOAuthProvider — OAuthClientProvider subclass with disk-watch ----
class _HermesRuntimeProviderMixin:
"""Runtime-only provider behaviour layered over ``HermesProviderMixin``: pre-flow disk-mtime
reload, expiry seeding on cold load, pre-flight metadata discovery, dead-client-registration
detection and the bidirectional ``async_auth_flow`` bridge. Must precede the SDK class in
the MRO."""
_hermes_logger = logger
def __init__(self, *args: Any, server_name: str = "", preregistered: bool = False, **kwargs: Any):
super().__init__(*args, **kwargs)
# mcp 2.0 uses a task-owned anyio.Lock held across the yielded resource request: a
# session-long GET blocks every concurrent POST, and HTTPX may close the auth-flow
# generator from another task. A binary semaphore keeps mutual exclusion without task
# ownership; async_auth_flow narrows its scope around resource I/O.
import anyio
self.context.lock = anyio.Semaphore(1, max_value=1)
self._hermes_server_name = server_name
self._hermes_home = ""
# A config-supplied (pre-registered) client_id rejected as invalid_client means the
# *config* is wrong — re-registration can't help, so only dynamically-registered
# clients auto-heal.
self._hermes_preregistered = preregistered
def _hermes_storage(self):
"""The context storage when it is a ``HermesTokenStorage``, else None."""
from tools.mcp_oauth import HermesTokenStorage
storage = self.context.storage
return storage if isinstance(storage, HermesTokenStorage) else None
def _log_nonfatal(self, what: str, exc: BaseException) -> None:
logger.debug("MCP OAuth '%s': %s failed (non-fatal): %s", self._hermes_server_name, what, exc)
async def _initialize(self) -> None:
"""Load stored state, seed ``token_expiry_time``, restore/prefetch metadata.
The SDK's ``_initialize`` populates ``current_tokens`` but never calls
``update_token_expiry``, so ``is_token_valid()`` is True for any loaded token regardless
of age and a restarted process ships stale Bearer tokens (some providers answer 200 with
an app-level auth error the transport can't see). Seeding the expiry makes the SDK take
``can_refresh_token()`` and refresh first; ``HermesTokenStorage`` persists absolute
``expires_at`` so the TTL reflects wall-clock age. Metadata is restored from disk, else
discovered pre-flight when we hold tokens but no metadata: otherwise ``_refresh_token``
guesses ``{server_url}/token`` (wrong for split-origin providers such as BetterStack),
404s, and we fall through to browser reauth.
"""
await super()._initialize()
tokens = self.context.current_tokens
if tokens is not None and tokens.expires_in is not None:
self.context.update_token_expiry(tokens)
storage = self._hermes_storage()
if storage is not None and self.context.oauth_metadata is None:
meta = storage.load_oauth_metadata()
if meta is not None:
self.context.oauth_metadata = meta
logger.debug(
"MCP OAuth '%s': restored metadata from disk (token_endpoint=%s)",
self._hermes_server_name, meta.token_endpoint,
)
if tokens is not None and self.context.oauth_metadata is None:
try:
await self._prefetch_oauth_metadata()
except Exception as exc: # pragma: no cover — non-fatal: the SDK's 401-branch discovery runs next request
self._log_nonfatal("pre-flight metadata discovery", exc)
async def _prefetch_oauth_metadata(self) -> None:
"""Fetch PRM + ASM from the well-known endpoints and cache on context. Mirrors the SDK's
401-branch discovery but runs before the first request, using the SDK's own URL
builders/response handlers so we track whatever the pinned SDK version expects."""
# The SDK's httpx flavour, not Hermes' — mcp 2.0 builds on httpx2 and
# `create_oauth_metadata_request` returns *its* Request objects, which only its own
# AsyncClient can send (tools.mcp_tool.sdk_httpx).
from tools.mcp_tool import sdk_httpx
httpx = sdk_httpx()
if httpx is None: # pragma: no cover — SDK import would have failed
return
from mcp.client.auth.utils import (
build_oauth_authorization_server_metadata_discovery_urls,
build_protected_resource_metadata_discovery_urls,
create_oauth_metadata_request,
handle_auth_metadata_response,
handle_protected_resource_response,
)
server_url = self.context.server_url
async def _send(client, url: str, label: str):
try:
return await client.send(create_oauth_metadata_request(url))
except httpx.HTTPError as exc:
logger.debug("MCP OAuth '%s': %s discovery to %s failed: %s", self._hermes_server_name, label, url, exc)
return None
async with httpx.AsyncClient(timeout=10.0) as client:
# Step 1: PRM discovery to learn the authorization_server URL.
for url in build_protected_resource_metadata_discovery_urls(None, server_url):
resp = await _send(client, url, "PRM")
prm = await handle_protected_resource_response(resp) if resp is not None else None
if prm:
self.context.protected_resource_metadata = prm
if prm.authorization_servers:
self.context.auth_server_url = str(prm.authorization_servers[0])
break
# Step 2: ASM discovery against auth_server_url (server_url fallback for legacy providers).
for url in build_oauth_authorization_server_metadata_discovery_urls(self.context.auth_server_url, server_url):
resp = await _send(client, url, "ASM")
if resp is None:
continue
ok, asm = await handle_auth_metadata_response(resp)
if not ok:
break
if asm:
self.context.oauth_metadata = asm
# Persist now so a later cold-load skips discovery.
storage = self._hermes_storage()
if storage is not None:
storage.save_oauth_metadata(asm)
logger.debug(
"MCP OAuth '%s': pre-flight ASM discovered token_endpoint=%s",
self._hermes_server_name, asm.token_endpoint,
)
break
def _persist_oauth_metadata_if_changed(self) -> None:
"""Save metadata the SDK discovered lazily (401 branch) for future restarts; no-op when
absent, not our storage, or unchanged."""
meta = self.context.oauth_metadata
storage = self._hermes_storage()
if meta is None or storage is None:
return
existing = storage.load_oauth_metadata()
if existing is None or str(existing.token_endpoint) != str(meta.token_endpoint):
storage.save_oauth_metadata(meta)
async def _is_invalid_client_at_token_endpoint(self, response: Any) -> bool:
"""True when *response* is the token endpoint rejecting our client_id with
``invalid_client`` (whole word, so RFC 7591's ``invalid_client_metadata`` does not trip
it). The body is read only after the endpoint matches."""
meta = getattr(self.context, "oauth_metadata", None)
token_endpoint = str(meta.token_endpoint) if meta is not None and getattr(meta, "token_endpoint", None) else None
req = getattr(response, "request", None)
req_url = str(req.url) if req is not None else None
if not token_endpoint or not req_url or not _same_endpoint(req_url, token_endpoint):
return False
body = await response.aread()
return re.search(rb"\binvalid_client\b", body.lower()) is not None
async def _maybe_flag_poisoned_client(self, response: Any) -> None:
"""Detect a dead client registration and force re-registration.
An ``invalid_client`` rejection of our ``client_id`` at the token endpoint (exchange or
refresh) proves the cached registration is dead server-side; delete ``client.json``
(+ stale metadata) so the SDK re-runs DCR next flow. The browser-side "Redirect URI
Mismatch" case has no HTTP signal and is left to ``hermes mcp reauth``.
Conservative by construction — acts ONLY when status is 400/401, the request hit the
discovered ``token_endpoint`` (the only request carrying our ``client_id``), and the body
carries ``invalid_client``. Pre-registered clients are never poisoned. Best-effort: any
failure is swallowed so a miss never breaks the live flow. If ``token_endpoint`` was
never discovered the guard returns early.
"""
try:
if self._hermes_preregistered or getattr(response, "status_code", None) not in (400, 401):
return
if not await self._is_invalid_client_at_token_endpoint(response):
return
storage = self._hermes_storage()
# If the rejected client_id was our CIMD URL, re-presenting it would loop (the
# server already fetched and refused it). Drop the URL so the retry takes DCR, and
# mark it on disk so the next process doesn't walk back into the same refusal
# (`hermes mcp login` clears the marker).
cimd_url = getattr(self.context, "client_metadata_url", None)
rejected_id = getattr(self.context.client_info, "client_id", None)
if cimd_url and rejected_id == cimd_url:
logger.warning(
"MCP OAuth '%s': authorization server rejected our Client ID Metadata Document (%s) "
"with invalid_client — falling back to dynamic client registration.",
self._hermes_server_name, cimd_url,
)
self.context.client_metadata_url = None
if storage is not None:
storage.mark_cimd_rejected()
if storage is not None:
storage.poison_client_registration()
# Drop the in-memory client so the SDK re-registers next flow.
self.context.client_info = None
self._initialized = False
except Exception as exc: # pragma: no cover — defensive, must not throw
self._log_nonfatal("invalid_client detection", exc)
async def async_auth_flow(self, request): # type: ignore[override]
# Pre-flow hook: reload from disk if it changed (non-fatal on error).
try:
await get_manager().invalidate_if_disk_changed(self._hermes_server_name, hermes_home=self._hermes_home)
except Exception as exc: # pragma: no cover — defensive
self._log_nonfatal("pre-flow disk-watch", exc)
# Bridge the bidirectional generator protocol by hand: httpx feeds responses back via
# ``auth_flow.asend(response)``. A naive ``async for item in inner: yield item``
# DISCARDS those values, so the SDK's ``response = yield request`` sees None and
# crashes on ``response.status_code``.
inner = super().async_auth_flow(request)
resource_lock_released = False
sent_access_token = None
retry_after_concurrent_auth = False
try:
outgoing = await inner.__anext__()
while True:
# The SDK holds context.lock for its whole generator, even while HTTPX waits on
# the MCP request. Release it for that request only; discovery/refresh/
# registration/exchange stay serialized exactly as the SDK implements them.
if outgoing is request:
tokens = self.context.current_tokens
sent_access_token = tokens.access_token if tokens is not None else None
self.context.lock.release()
resource_lock_released = True
incoming = yield outgoing
if resource_lock_released:
await self.context.lock.acquire()
resource_lock_released = False
# Another request may have refreshed/authorized while this one was in flight:
# retry with that token instead of a duplicate OAuth transition from the stale
# 401/403.
tokens = self.context.current_tokens
if (
getattr(incoming, "status_code", None) in (401, 403)
and self.context.is_token_valid()
and tokens is not None
and tokens.access_token != sent_access_token
):
self._add_auth_header(request)
await inner.aclose()
retry_after_concurrent_auth = True
break
# Sniff for a dead-client-registration signal (best-effort).
await self._maybe_flag_poisoned_client(incoming)
outgoing = await inner.asend(incoming)
except StopAsyncIteration:
# Persist metadata discovered lazily in the 401 branch.
self._persist_oauth_metadata_if_changed()
return
finally:
if resource_lock_released:
# Balance the SDK's surrounding ``async with`` even when HTTPX cancels/closes
# the flow mid-request. Shield only this local bookkeeping.
import anyio
with anyio.CancelScope(shield=True):
await self.context.lock.acquire()
if retry_after_concurrent_auth:
yield request
self._persist_oauth_metadata_if_changed()
return
def _make_hermes_provider_class() -> Optional[type]:
"""Lazy-import the SDK base class and return our subclass (None if the SDK's OAuth module is
unavailable, so this module still imports)."""
try:
from mcp.client.auth.oauth2 import OAuthClientProvider
except ImportError: # pragma: no cover — SDK required in CI
return None
class HermesMCPOAuthProvider(_HermesRuntimeProviderMixin, HermesProviderMixin, OAuthClientProvider):
"""OAuthClientProvider with pre-flow disk-mtime reload: before every ``async_auth_flow``
the manager checks whether the tokens file changed on disk and, if so, resets
``_initialized`` so the next flow re-reads storage — making external refreshes visible
to a running session. Token-endpoint fixes come from ``HermesProviderMixin``."""
return HermesMCPOAuthProvider
# Cached at import time. Tested and used by :class:`MCPOAuthManager`.
_HERMES_PROVIDER_CLS: Optional[type] = _make_hermes_provider_class()
# -- Manager -----------------------------------------------------------------
class MCPOAuthManager:
"""Single source of truth for per-server MCP OAuth state. Thread-safe: the ``_entries`` dict
is guarded by ``_entries_lock`` for get-or-create semantics; per-entry state is guarded by
the entry's own ``asyncio.Lock`` (used from the MCP event loop thread)."""
def __init__(self) -> None:
self._entries: dict[tuple[str, str], _ProviderEntry] = {}
self._entries_lock = threading.Lock()
# Strong refs to in-flight 401 tasks so the loop's weak bookkeeping cannot GC them
# mid-run and leave `await pending` hanging forever.
self._inflight_tasks: set[asyncio.Task] = set()
# -- Provider construction / caching --
def get_or_build_provider(self, server_name: str, server_url: str, oauth_config: Optional[dict]) -> Optional[Any]:
"""Return a cached OAuth provider for ``server_name`` or build one. Idempotent: repeat
calls with the same name return the same instance; if ``server_url`` changes for a
given name the cached entry is discarded and a fresh provider is built. None if the MCP
SDK's OAuth support is unavailable."""
key = self._key(server_name)
with self._entries_lock:
entry = self._entries.get(key)
if entry is not None and entry.server_url != server_url:
logger.info("MCP OAuth '%s': URL changed from %s to %s, discarding cache", server_name, entry.server_url, server_url)
entry = None
if entry is None:
entry = _ProviderEntry(server_url=server_url, oauth_config=oauth_config)
self._entries[key] = entry
if entry.provider is None:
entry.provider = self._build_provider(server_name, entry)
if entry.provider is not None:
entry.provider._hermes_home = key[0]
return entry.provider
@staticmethod
def _key(server_name: str, hermes_home: str | Path | None = None) -> tuple[str, str]:
from hermes_constants import get_hermes_home
home = Path(hermes_home) if hermes_home is not None else get_hermes_home()
return (str(home.expanduser().resolve(strict=False)), server_name)
def _build_provider(self, server_name: str, entry: _ProviderEntry) -> Optional[Any]:
"""Build a :class:`HermesMCPOAuthProvider` from the shared ``tools.mcp_oauth`` helpers;
None if the SDK's OAuth support is unavailable."""
if _HERMES_PROVIDER_CLS is None:
logger.warning("MCP OAuth '%s': SDK auth module unavailable", server_name)
return None
# Local imports avoid circular deps at module import time.
from tools.mcp_dashboard_oauth import get_dashboard_oauth_flow
from tools.mcp_oauth import _OAUTH_AVAILABLE, OAuthNonInteractiveError, _is_interactive
from tools.mcp_oauth_provider import build_provider_kwargs, prepare_oauth_config
if not _OAUTH_AVAILABLE:
return None
cfg, storage = prepare_oauth_config(server_name, entry.server_url, entry.oauth_config)
if get_dashboard_oauth_flow() is None and not _is_interactive() and not storage.has_cached_tokens():
raise OAuthNonInteractiveError(
f"MCP OAuth for '{server_name}': non-interactive environment and no cached tokens found. "
f"Run `hermes mcp login {server_name}` interactively first to complete initial authorization."
)
return _HERMES_PROVIDER_CLS(
server_name=server_name,
preregistered=bool(cfg.get("client_id")),
server_url=entry.server_url,
**build_provider_kwargs(cfg, storage, ssh_proxy_hint=False),
)
def remove(self, server_name: str, *, hermes_home: str | Path | None = None) -> _ProviderEntry | None:
"""Evict the provider from cache AND delete tokens from disk (``hermes mcp remove`` and,
indirectly, ``hermes mcp login`` during forced re-auth)."""
entry = self.evict(server_name, hermes_home=hermes_home)
from tools.mcp_oauth import remove_oauth_tokens
remove_oauth_tokens(server_name, hermes_home=hermes_home)
logger.info("MCP OAuth '%s': evicted from cache and removed from disk", server_name)
return entry
def restore_entry(
self, server_name: str, entry: _ProviderEntry | None, *, hermes_home: str | Path | None = None
) -> None:
"""Restore a provider entry removed for a failed reauthorization."""
if entry is None:
return
with self._entries_lock:
self._entries.setdefault(self._key(server_name, hermes_home), entry)
def evict(self, server_name: str, *, hermes_home: str | Path | None = None) -> _ProviderEntry | None:
"""Drop only the in-process provider, preserving persisted OAuth state."""
with self._entries_lock:
return self._entries.pop(self._key(server_name, hermes_home), None)
# -- Disk watch --
async def invalidate_if_disk_changed(self, server_name: str, *, hermes_home: str | Path | None = None) -> bool:
"""Force the SDK provider to reload when the tokens file mtime changed; True if
invalidated. This is the external-refresh fix: a cron job writes fresh tokens and the
next tool call picks them up."""
from tools.mcp_oauth import _get_token_dir, _safe_filename
entry = self._entries.get(self._key(server_name, hermes_home))
if entry is None or entry.provider is None:
return False
async with entry.lock:
tokens_path = _get_token_dir(hermes_home) / f"{_safe_filename(server_name)}.json"
try:
mtime_ns = tokens_path.stat().st_mtime_ns
except (FileNotFoundError, OSError):
return False
if mtime_ns == entry.last_mtime_ns:
return False
old = entry.last_mtime_ns
entry.last_mtime_ns = mtime_ns
# `_initialized` is private SDK API but stable across the versions we pin
# (>=1.26.0); resetting it forces a reload.
if hasattr(entry.provider, "_initialized"):
entry.provider._initialized = False # noqa: SLF001
logger.info("MCP OAuth '%s': tokens file changed (mtime %d -> %d), forcing reload", server_name, old, mtime_ns)
return True
# -- 401 handler (dedup'd) --
async def _recover_401(self, server_name: str, entry: _ProviderEntry, key: str, pending: asyncio.Future) -> None:
"""Single recovery attempt behind *pending*; always clears the dedup slot."""
try:
# Step 1: Did disk change? Picks up external refresh.
if await self.invalidate_if_disk_changed(server_name):
if not pending.done():
pending.set_result(True)
return
# Step 2: No disk change — if the SDK can refresh in place, let the caller retry
# (the httpx.Auth flow refreshes on the next request).
can_refresh_fn = getattr(getattr(entry.provider, "context", None), "can_refresh_token", None)
try:
can_refresh = bool(can_refresh_fn()) if callable(can_refresh_fn) else False
except Exception:
can_refresh = False
if not pending.done():
pending.set_result(can_refresh)
except Exception as exc: # pragma: no cover — defensive
logger.warning("MCP OAuth '%s': 401 handler failed: %s", server_name, exc)
if not pending.done():
pending.set_result(False)
finally:
entry.pending_401.pop(key, None)
async def handle_401(self, server_name: str, failed_access_token: Optional[str] = None) -> bool:
"""Handle a 401 from a tool call, deduplicated across concurrent callers. True: a
(possibly new) access token is available — caller should reconnect and retry. False: no
recovery path — caller should surface a ``needs_reauth`` error so the model stops
hallucinating manual refreshes. Thundering-herd protection: N concurrent 401s with the
same ``failed_access_token`` fire one recovery attempt; the rest await its future."""
entry = self._entries.get(self._key(server_name))
if entry is None or entry.provider is None:
return False
key = failed_access_token or "<unknown>"
loop = asyncio.get_running_loop()
async with entry.lock:
pending = entry.pending_401.get(key)
if pending is None:
pending = loop.create_future()
entry.pending_401[key] = pending
task = asyncio.create_task(self._recover_401(server_name, entry, key, pending))
self._inflight_tasks.add(task)
task.add_done_callback(self._inflight_tasks.discard)
try:
return await pending
except Exception as exc: # pragma: no cover — defensive
logger.warning("MCP OAuth '%s': awaiting 401 handler failed: %s", server_name, exc)
return False
# -- Module-level singleton ---------------------------------------------------
_MANAGER: Optional[MCPOAuthManager] = None
_MANAGER_LOCK = threading.Lock()
def get_manager() -> MCPOAuthManager:
"""Return the process-wide :class:`MCPOAuthManager` singleton."""
global _MANAGER
with _MANAGER_LOCK:
if _MANAGER is None:
_MANAGER = MCPOAuthManager()
return _MANAGER
def reset_manager_for_tests() -> None:
"""Test-only helper: drop the singleton so fixtures start clean."""
global _MANAGER
with _MANAGER_LOCK:
_MANAGER = None