feat: add MCP server core, stdio and streamable HTTP transports and serve command

Low-level SDK server built from the catalog plus gitea_api_request, with TOOLSETS/READ_ONLY/DISABLED_TOOLS filters, schema validation without value echo, one audit event per call, static bearer verifier, identity resolver hook, /health, DNS-rebinding protection, rate limiting and fail-closed startup checks.

tests/test_transports.py

@@ -0,0 +1,450 @@
+"""Tests for the streamable HTTP app: health, auth, DNS-rebinding, rate limiting, MCP e2e."""
+
+from __future__ import annotations
+
+import json
+import logging
+from collections.abc import AsyncIterator, Iterator
+from contextlib import asynccontextmanager
+from typing import Any
+
+import httpx
+import httpx2
+import pytest
+from mcp import Client
+from mcp.client.streamable_http import streamable_http_client
+from mcp.server.auth.provider import AccessToken
+from pytest_httpx import HTTPXMock
+from starlette.routing import Route
+from starlette.testclient import TestClient
+
+from aegis_gitea_mcp import __version__
+from aegis_gitea_mcp.auth import STATIC_CLIENT_ID
+from aegis_gitea_mcp.config import Settings
+from aegis_gitea_mcp.gitea import RAW_TOOL_NAME
+from aegis_gitea_mcp.identity import Identity
+from aegis_gitea_mcp.transports import (
+    GiteaProbe,
+    build_http_app,
+    transport_security,
+)
+from tests.test_server_helpers import (
+    ANY_HOST,
+    API,
+    BEARER_TOKEN,
+    GITEA_TOKEN,
+    mock_user,
+    server_settings,
+)
+
+BASE = "http://127.0.0.1:8080"
+INITIALIZE = {
+    "jsonrpc": "2.0",
+    "id": 1,
+    "method": "initialize",
+    "params": {
+        "protocolVersion": "2025-06-18",
+        "capabilities": {},
+        "clientInfo": {"name": "test", "version": "0"},
+    },
+}
+MCP_HEADERS = {
+    "Content-Type": "application/json",
+    "Accept": "application/json, text/event-stream",
+}
+
+
+@pytest.fixture(autouse=True)
+def _env(mock_env: None) -> None:
+    """The audit logger and rate limiter read GITEA_URL from the environment."""
+
+
+def http_settings(**overrides: Any) -> Settings:
+    """Settings with a bearer token on port 8080."""
+    values: dict[str, Any] = {"mcp_bearer_token": BEARER_TOKEN, "mcp_port": 8080}
+    values.update(overrides)
+    return server_settings(**values)
+
+
+@pytest.fixture
+def client(request: pytest.FixtureRequest) -> Iterator[TestClient]:
+    settings = http_settings()
+    with TestClient(build_http_app(settings), base_url=BASE) as test_client:
+        yield test_client
+
+
+def auth(token: str = BEARER_TOKEN) -> dict[str, str]:
+    return {"Authorization": f"Bearer {token}"}
+
+
+# Health and index
+
+
+def test_health_ok_uses_the_admin_token_and_is_cached(
+    client: TestClient, httpx_mock: HTTPXMock
+) -> None:
+    httpx_mock.add_response(url=f"{API}/version", json={"version": "1.22"})
+
+    first = client.get("/health")
+    second = client.get("/health")
+
+    assert first.status_code == second.status_code == 200
+    assert first.json() == {
+        "status": "ok",
+        "version": __version__,
+        "tools": 538,
+        "gitea": "reachable",
+    }
+    requests = httpx_mock.get_requests()
+    assert len(requests) == 1  # 10 second cache
+    assert requests[0].headers["Authorization"] == f"token {GITEA_TOKEN}"
+
+
+@pytest.mark.parametrize(
+    "outcome",
+    [
+        httpx.Response(500, text="gitea exploded at https://gitea.example.com " + GITEA_TOKEN),
+        httpx.Response(302, headers={"Location": "https://elsewhere.example/"}),
+        httpx.ConnectError("connection refused to https://gitea.example.com"),
+        httpx.ReadTimeout("slow"),
+    ],
+)
+def test_health_degraded_leaks_nothing(
+    client: TestClient, httpx_mock: HTTPXMock, outcome: httpx.Response | Exception
+) -> None:
+    if isinstance(outcome, Exception):
+        httpx_mock.add_exception(outcome)
+    else:
+        httpx_mock.add_response(
+            status_code=outcome.status_code, headers=outcome.headers, content=outcome.content
+        )
+
+    response = client.get("/health")
+
+    assert response.status_code == 503
+    assert response.json() == {"status": "degraded", "gitea": "unreachable"}
+    assert "gitea.example.com" not in response.text and GITEA_TOKEN not in response.text
+
+
+def test_health_probe_without_a_token_is_anonymous(httpx_mock: HTTPXMock) -> None:
+    httpx_mock.add_response(url=f"{API}/version", json={})
+    settings = http_settings(gitea_token=None)
+
+    with TestClient(build_http_app(settings), base_url=BASE) as test_client:
+        assert test_client.get("/health").status_code == 200
+
+    assert "Authorization" not in httpx_mock.get_requests()[0].headers
+
+
+def test_health_recovers_after_the_cache_expires(
+    client: TestClient, httpx_mock: HTTPXMock, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    from aegis_gitea_mcp import transports
+
+    clock = [100.0]
+    monkeypatch.setattr(transports.time, "monotonic", lambda: clock[0])
+    httpx_mock.add_exception(httpx.ConnectError("down"))
+    httpx_mock.add_response(url=f"{API}/version", json={})
+
+    assert client.get("/health").status_code == 503
+    assert client.get("/health").status_code == 503  # still cached
+    clock[0] += 11
+    assert client.get("/health").status_code == 200
+
+
+def test_health_and_index_need_no_token(client: TestClient, httpx_mock: HTTPXMock) -> None:
+    httpx_mock.add_response(url=f"{API}/version", json={})
+
+    assert client.get("/").json() == {
+        "name": "aegis-gitea-mcp",
+        "version": __version__,
+        "mcp_endpoint": "/mcp",
+    }
+    assert client.get("/health").status_code == 200
+
+
+async def test_probe_closes_only_its_own_client() -> None:
+    settings = http_settings()
+    own = GiteaProbe(settings)
+    await own.aclose()
+    assert own._client.is_closed
+
+    shared = httpx.AsyncClient()
+    borrowed = GiteaProbe(settings, shared)
+    await borrowed.aclose()
+    assert not shared.is_closed
+    await shared.aclose()
+
+
+# Authentication
+
+
+def test_mcp_without_token_is_401_with_resource_metadata(client: TestClient) -> None:
+    response = client.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS)
+
+    assert response.status_code == 401
+    challenge = response.headers["WWW-Authenticate"]
+    assert challenge.startswith("Bearer ")
+    assert (
+        'resource_metadata="http://127.0.0.1:8080/.well-known/oauth-protected-resource/mcp"'
+        in challenge
+    )
+
+
+@pytest.mark.parametrize("token", ["wrong", BEARER_TOKEN + "x", ""])
+def test_mcp_with_wrong_token_is_401(client: TestClient, token: str) -> None:
+    response = client.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth(token)})
+
+    assert response.status_code == 401
+    assert "resource_metadata" in response.headers["WWW-Authenticate"]
+
+
+def test_mcp_initialize_with_the_right_token(client: TestClient) -> None:
+    response = client.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth()})
+
+    assert response.status_code == 200
+    body = response.text
+    assert "aegis-gitea-mcp" in body
+    assert BEARER_TOKEN not in body
+
+
+def test_protected_resource_metadata_names_the_mcp_endpoint(client: TestClient) -> None:
+    response = client.get("/.well-known/oauth-protected-resource/mcp")
+
+    assert response.status_code == 200
+    assert response.json()["resource"] == "http://127.0.0.1:8080/mcp"
+
+
+@asynccontextmanager
+async def sdk_client(app: Any, token: str | None = BEARER_TOKEN) -> AsyncIterator[Client]:
+    """The SDK client talking to ``app`` over an in-process ASGI transport."""
+    headers = {"Authorization": f"Bearer {token}"} if token else {}
+    async with (
+        app.router.lifespan_context(app),
+        httpx2.AsyncClient(
+            transport=httpx2.ASGITransport(app=app), headers=headers, base_url=BASE
+        ) as http_client,
+        Client(streamable_http_client(f"{BASE}/mcp", http_client=http_client)) as c,
+    ):
+        yield c
+
+
+async def test_sdk_client_lists_and_calls_tools_as_the_admin(httpx_mock: HTTPXMock) -> None:
+    mock_user(httpx_mock, "admin")
+    httpx_mock.add_response(url=f"{API}/repos/octo/demo", json={"full_name": "octo/demo"})
+    app = build_http_app(http_settings())
+
+    async with sdk_client(app) as c:
+        assert len((await c.list_tools()).tools) == 538
+        result = await c.call_tool("gitea_repo_get", {"owner": "octo", "repo": "demo"})
+
+    assert not result.is_error
+    payload = json.loads(result.content[0].text)  # type: ignore[union-attr]
+    assert payload["identity"] == {"login": "admin", "mode": "admin-token", "sudo": None}
+    assert payload["data"] == {"full_name": "octo/demo"}
+
+
+async def test_access_token_reaches_the_identity_resolver() -> None:
+    seen: list[AccessToken | None] = []
+
+    class Spy:
+        async def resolve(self, access: AccessToken | None) -> Identity:
+            seen.append(access)
+            return Identity(login="spy", mode="admin-token", token=GITEA_TOKEN)
+
+    from aegis_gitea_mcp.server import build_server
+
+    settings = http_settings()
+    app = build_http_app(settings, server=build_server(settings, resolver=Spy()))
+
+    async with sdk_client(app) as c:
+        await c.call_tool("gitea_repo_get", {"owner": "bad owner", "repo": "x"})  # invalid
+        await c.call_tool(RAW_TOOL_NAME, {"method": "GET", "path": "/version"})
+
+    assert len(seen) == 1 and seen[0] is not None
+    assert seen[0].client_id == STATIC_CLIENT_ID
+    assert BEARER_TOKEN not in repr(seen[0])
+
+
+# DNS rebinding and origin
+
+
+def test_bad_host_header_is_rejected(httpx_mock: HTTPXMock) -> None:
+    with TestClient(build_http_app(http_settings()), base_url="http://evil.example:8080") as c:
+        response = c.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth()})
+
+    assert response.status_code == 421
+
+
+def test_bad_origin_is_rejected(client: TestClient) -> None:
+    response = client.post(
+        "/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth(), "Origin": "https://evil.example"}
+    )
+
+    assert response.status_code == 403
+
+
+def test_public_host_is_allowed_when_configured() -> None:
+    settings = http_settings(public_base_url="https://mcp.example.com")
+    with TestClient(build_http_app(settings), base_url="https://mcp.example.com") as c:
+        ok = c.post(
+            "/mcp",
+            json=INITIALIZE,
+            headers={**MCP_HEADERS, **auth(), "Origin": "https://mcp.example.com"},
+        )
+        metadata = c.get("/.well-known/oauth-protected-resource/mcp")
+        challenge = c.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS)
+
+    assert ok.status_code == 200
+    assert metadata.json()["resource"] == "https://mcp.example.com/mcp"
+    assert (
+        "https://mcp.example.com/.well-known/oauth-protected-resource/mcp"
+        in (challenge.headers["WWW-Authenticate"])
+    )
+
+
+def test_transport_security_hosts_and_origins() -> None:
+    settings = http_settings(
+        mcp_host="192.168.1.5",
+        public_base_url="https://mcp.example.com:8443/",
+        allowed_hosts=["proxy.internal:9000"],
+    )
+
+    security = transport_security(settings)
+
+    assert security.enable_dns_rebinding_protection is True
+    assert security.allowed_hosts == [
+        "127.0.0.1:8080",
+        "localhost:8080",
+        "[::1]:8080",
+        "192.168.1.5:8080",
+        "mcp.example.com:8443",
+        "mcp.example.com",
+        "proxy.internal:9000",
+    ]
+    assert "https://mcp.example.com:8443" in security.allowed_origins
+    assert "https://proxy.internal:9000" in security.allowed_origins
+    assert "http://127.0.0.1:8080" in security.allowed_origins
+
+
+def test_transport_security_wildcard_bind_adds_no_bind_host() -> None:
+    security = transport_security(http_settings(mcp_host=ANY_HOST))
+
+    assert security.allowed_hosts == ["127.0.0.1:8080", "localhost:8080", "[::1]:8080"]
+
+
+# Rate limiting
+
+
+def test_rate_limit_returns_429_on_the_mcp_path_only(
+    httpx_mock: HTTPXMock, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    # The limiter reads the process-wide settings.
+    monkeypatch.setenv("RATE_LIMIT_PER_MINUTE", "2")
+    httpx_mock.add_response(url=f"{API}/version", json={}, is_reusable=True)
+    settings = http_settings(rate_limit_per_minute=2)
+    with TestClient(build_http_app(settings), base_url=BASE) as c:
+        statuses = [
+            c.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS).status_code for _ in range(3)
+        ]
+        limited = c.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS)
+        health = c.get("/health")
+
+    assert statuses == [401, 401, 429]
+    assert limited.status_code == 429
+    assert limited.json()["error"]["kind"] == "rate_limited"
+    assert limited.headers["Retry-After"] == "60"
+    assert health.status_code == 200
+
+
+def test_rate_limit_is_keyed_per_token(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("RATE_LIMIT_PER_MINUTE", "1")
+    settings = http_settings(rate_limit_per_minute=1)
+    with TestClient(build_http_app(settings), base_url=BASE) as c:
+        first = c.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth()})
+
+    assert first.status_code == 200
+    from aegis_gitea_mcp.rate_limit import get_rate_limiter
+
+    limiter = get_rate_limiter()
+    assert limiter._token_limiter.max_requests == 1
+    # The raw header is never used as a key, only its hash.
+    keys = list(limiter._token_limiter._events)
+    assert keys and all(BEARER_TOKEN not in key for key in keys)
+
+
+# Auth wiring
+
+
+def test_no_auth_on_loopback_works_and_warns(caplog: pytest.LogCaptureFixture) -> None:
+    settings = http_settings(mcp_bearer_token=None)
+    with caplog.at_level(logging.WARNING):
+        app = build_http_app(settings)
+    with TestClient(app, base_url=BASE) as c:
+        response = c.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS)
+        metadata = c.get("/.well-known/oauth-protected-resource/mcp")
+
+    assert response.status_code == 200
+    assert metadata.status_code == 404
+    assert "WITHOUT authentication" in caplog.text
+
+
+def test_extra_verifier_is_combined_with_the_static_bearer() -> None:
+    class Other:
+        async def verify_token(self, token: str) -> AccessToken | None:
+            if token == "oauth-token":
+                return AccessToken(token="t", client_id="oauth-client", scopes=[])
+            return None
+
+    app = build_http_app(http_settings(), token_verifier=Other())
+    with TestClient(app, base_url=BASE) as c:
+        static = c.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth()})
+        oauth = c.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth("oauth-token")})
+        denied = c.post("/mcp", json=INITIALIZE, headers={**MCP_HEADERS, **auth("nope")})
+
+    assert (static.status_code, oauth.status_code, denied.status_code) == (200, 200, 401)
+
+
+def test_only_an_extra_verifier_protects_the_endpoint() -> None:
+    class Other:
+        async def verify_token(self, token: str) -> AccessToken | None:
+            return None
+
+    app = build_http_app(http_settings(mcp_bearer_token=None), token_verifier=Other())
+    with TestClient(app, base_url=BASE) as c:
+        assert c.post("/mcp", json=INITIALIZE, headers=MCP_HEADERS).status_code == 401
+
+
+def test_auth_provider_without_a_verifier_is_refused() -> None:
+    with pytest.raises(ValueError, match="token verifier"):
+        build_http_app(
+            http_settings(mcp_bearer_token=None),
+            auth_server_provider=object(),  # type: ignore[arg-type]
+        )
+
+
+def test_extra_routes_are_served_without_mcp_auth() -> None:
+    from starlette.responses import PlainTextResponse
+
+    async def callback(request: Any) -> PlainTextResponse:
+        return PlainTextResponse("ok")
+
+    app = build_http_app(http_settings(), extra_routes=[Route("/oauth/callback", callback)])
+    with TestClient(app, base_url=BASE) as c:
+        assert c.get("/oauth/callback").text == "ok"
+
+
+def test_request_body_cap_admits_a_full_size_upload() -> None:
+    settings = http_settings(max_binary_bytes=5_242_880)
+    app = build_http_app(settings)
+    with TestClient(app, base_url=BASE) as c:
+        padding = "x" * (6 * 1024 * 1024)
+        body = {**INITIALIZE, "params": {**INITIALIZE["params"], "padding": padding}}
+        response = c.post("/mcp", json=body, headers={**MCP_HEADERS, **auth()})
+
+    assert response.status_code != 413
+
+    small = build_http_app(http_settings(max_binary_bytes=1))
+    with TestClient(small, base_url=BASE) as c:
+        rejected = c.post("/mcp", json=body, headers={**MCP_HEADERS, **auth()})
+    assert rejected.status_code == 413