Add server argument to specify custom PAA root certificate location (#622)

Author: agners

matter_server/server/__main__.py

@@ -91,6 +91,12 @@
     default=None,
     help="Primary network interface for link-local addresses (optional).",
 )
+parser.add_argument(
+    "--paa-root-cert-dir",
+    type=str,
+    default=None,
+    help="Directory where PAA root certificates are stored.",
+)
 
 args = parser.parse_args()
 
@@ -175,6 +181,7 @@ def main() -> None:
         int(args.port),
         args.listen_address,
         args.primary_interface,
+        args.paa_root_cert_dir,
     )
 
     async def handle_stop(loop: asyncio.AbstractEventLoop) -> None:

matter_server/server/const.py

@@ -11,11 +11,9 @@
 # and a full re-interview is mandatory
 DATA_MODEL_SCHEMA_VERSION = 6
 
-# the paa-root-certs path is hardcoded in the sdk at this time
-# and always uses the development subfolder
-# regardless of anything you pass into instantiating the controller
-# revisit this once matter 1.1 is released
-PAA_ROOT_CERTS_DIR: Final[pathlib.Path] = (
+# Keep default location inherited from early version of the Python
+# bindings.
+DEFAULT_PAA_ROOT_CERTS_DIR: Final[pathlib.Path] = (
     pathlib.Path(__file__)
     .parent.resolve()
     .parent.resolve()

matter_server/server/device_controller.py

@@ -9,6 +9,7 @@
 from datetime import datetime
 from functools import partial
 import logging
+from pathlib import Path
 from random import randint
 import time
 from typing import TYPE_CHECKING, Any, Callable, Iterable, TypeVar, cast
@@ -48,7 +49,7 @@
     MatterNodeEvent,
     NodePingResult,
 )
-from .const import DATA_MODEL_SCHEMA_VERSION, PAA_ROOT_CERTS_DIR
+from .const import DATA_MODEL_SCHEMA_VERSION
 from .helpers.paa_certificates import fetch_certificates
 
 if TYPE_CHECKING:
@@ -117,15 +118,15 @@ def __init__(
         self._mdns_event_timer: dict[str, asyncio.TimerHandle] = {}
         self._node_lock: dict[int, asyncio.Lock] = {}
 
-    async def initialize(self) -> None:
+    async def initialize(self, paa_root_cert_dir: Path) -> None:
         """Async initialize of controller."""
         # (re)fetch all PAA certificates once at startup
         # NOTE: this must be done before initializing the controller
-        await fetch_certificates()
+        await fetch_certificates(paa_root_cert_dir)
 
         # Instantiate the underlying ChipDeviceController instance on the Fabric
         self.chip_controller = self.server.stack.fabric_admin.NewController(
-            paaTrustStorePath=str(PAA_ROOT_CERTS_DIR)
+            paaTrustStorePath=str(paa_root_cert_dir)
         )
         self.compressed_fabric_id = cast(
             int, await self._call_sdk(self.chip_controller.GetCompressedFabricId)

matter_server/server/helpers/paa_certificates.py

@@ -11,14 +11,13 @@
 from datetime import UTC, datetime, timedelta
 import logging
 from os import makedirs
+from pathlib import Path
 import re
 
 from aiohttp import ClientError, ClientSession
 from cryptography import x509
 from cryptography.hazmat.primitives import serialization
 
-from matter_server.server.const import PAA_ROOT_CERTS_DIR
-
 # Git repo details
 OWNER = "project-chip"
 REPO = "connectedhomeip"
@@ -33,14 +32,16 @@
 LAST_CERT_IDS: set[str] = set()
 
 
-async def write_paa_root_cert(certificate: str, subject: str) -> None:
+async def write_paa_root_cert(
+    paa_root_cert_dir: Path, certificate: str, subject: str
+) -> None:
     """Write certificate from string to file."""
 
     def _write() -> None:
         filename_base = "dcld_mirror_" + re.sub(
             "[^a-zA-Z0-9_-]", "", re.sub("[=, ]", "_", subject)
         )
-        filepath_base = PAA_ROOT_CERTS_DIR.joinpath(filename_base)
+        filepath_base = paa_root_cert_dir.joinpath(filename_base)
         # handle PEM certificate file
         file_path_pem = f"{filepath_base}.pem"
         LOGGER.debug("Writing certificate %s", file_path_pem)
@@ -58,6 +59,7 @@ def _write() -> None:
 
 
 async def fetch_dcl_certificates(
+    paa_root_cert_dir: Path,
     fetch_test_certificates: bool = True,
     fetch_production_certificates: bool = True,
 ) -> int:
@@ -99,6 +101,7 @@ async def fetch_dcl_certificates(
                     certificate = certificate.rstrip("\n")
 
                     await write_paa_root_cert(
+                        paa_root_cert_dir,
                         certificate,
                         subject,
                     )
@@ -119,7 +122,7 @@ async def fetch_dcl_certificates(
 # are correctly captured
 
 
-async def fetch_git_certificates() -> int:
+async def fetch_git_certificates(paa_root_cert_dir: Path) -> int:
     """Fetch Git PAA Certificates."""
     fetch_count = 0
     LOGGER.info("Fetching the latest PAA root certificates from Git.")
@@ -137,7 +140,7 @@ async def fetch_git_certificates() -> int:
                     continue
                 async with http_session.get(f"{GIT_URL}/{cert}.pem") as response:
                     certificate = await response.text()
-                await write_paa_root_cert(certificate, cert)
+                await write_paa_root_cert(paa_root_cert_dir, certificate, cert)
                 LAST_CERT_IDS.add(cert)
                 fetch_count += 1
     except (ClientError, TimeoutError) as err:
@@ -150,24 +153,18 @@ async def fetch_git_certificates() -> int:
     return fetch_count
 
 
-async def _get_certificate_age() -> datetime:
-    """Get last time PAA Certificates have been fetched."""
-    loop = asyncio.get_running_loop()
-    stat = await loop.run_in_executor(None, PAA_ROOT_CERTS_DIR.stat)
-    return datetime.fromtimestamp(stat.st_mtime, tz=UTC)
-
-
 async def fetch_certificates(
+    paa_root_cert_dir: Path,
     fetch_test_certificates: bool = True,
     fetch_production_certificates: bool = True,
 ) -> int:
     """Fetch PAA Certificates."""
     loop = asyncio.get_running_loop()
 
-    if not PAA_ROOT_CERTS_DIR.is_dir():
-        await loop.run_in_executor(None, makedirs, PAA_ROOT_CERTS_DIR)
+    if not paa_root_cert_dir.is_dir():
+        await loop.run_in_executor(None, makedirs, paa_root_cert_dir)
     else:
-        stat = await loop.run_in_executor(None, PAA_ROOT_CERTS_DIR.stat)
+        stat = await loop.run_in_executor(None, paa_root_cert_dir.stat)
         last_fetch = datetime.fromtimestamp(stat.st_mtime, tz=UTC)
         if last_fetch > datetime.now(tz=UTC) - timedelta(days=1):
             LOGGER.info(
@@ -176,13 +173,14 @@ async def fetch_certificates(
             return 0
 
     fetch_count = await fetch_dcl_certificates(
+        paa_root_cert_dir=paa_root_cert_dir,
         fetch_test_certificates=fetch_test_certificates,
         fetch_production_certificates=fetch_production_certificates,
     )
 
     if fetch_test_certificates:
-        fetch_count += await fetch_git_certificates()
+        fetch_count += await fetch_git_certificates(paa_root_cert_dir)
 
-    await loop.run_in_executor(None, PAA_ROOT_CERTS_DIR.touch)
+    await loop.run_in_executor(None, paa_root_cert_dir.touch)
 
     return fetch_count

matter_server/server/server.py

@@ -29,7 +29,7 @@
     ServerInfoMessage,
 )
 from ..server.client_handler import WebsocketClientHandler
-from .const import MIN_SCHEMA_VERSION
+from .const import DEFAULT_PAA_ROOT_CERTS_DIR, MIN_SCHEMA_VERSION
 from .device_controller import MatterDeviceController
 from .stack import MatterStack
 from .storage import StorageController
@@ -100,6 +100,7 @@ def __init__(
         port: int,
         listen_addresses: list[str] | None = None,
         primary_interface: str | None = None,
+        paa_root_cert_dir: Path | None = None,
     ) -> None:
         """Initialize the Matter Server."""
         self.storage_path = storage_path
@@ -108,6 +109,10 @@ def __init__(
         self.port = port
         self.listen_addresses = listen_addresses
         self.primary_interface = primary_interface
+        if paa_root_cert_dir is None:
+            self.paa_root_cert_dir = DEFAULT_PAA_ROOT_CERTS_DIR
+        else:
+            self.paa_root_cert_dir = Path(paa_root_cert_dir).absolute()
         self.logger = logging.getLogger(__name__)
         self.app = web.Application()
         self.loop: asyncio.AbstractEventLoop | None = None
@@ -134,7 +139,7 @@ async def start(self) -> None:
         self.loop = asyncio.get_running_loop()
         self.loop.set_exception_handler(_global_loop_exception_handler)
         self.loop.set_debug(os.environ.get("PYTHONDEBUG", "") != "")
-        await self.device_controller.initialize()
+        await self.device_controller.initialize(self.paa_root_cert_dir)
         await self.storage.start()
         await self.device_controller.start()
         await self.vendor_info.start()