fix(dtls): make reader-thread death visible and fail fast

The reader loop exited silently on any socket error, leaving conn/sock set so the session still looked open. Every later get()/post()/ping() then waited out its full request timeout on a session nobody was reading, raising SessionTimeoutError on repeat, forever. This started biting in v0.1.3 (d677c72), which moved to connected UDP sockets: a connected socket surfaces ICMP errors on recv, so one ECONNREFUSED from a rebooting appliance now killed the reader. - Advisory ICMP errnos (ECONNREFUSED/EHOSTUNREACH/...) no longer kill the reader; the next datagram usually works. - Real reader exits log at WARNING; close()-driven exits stay quiet. - A _reader_running Event lets get/post/ping/subscribe/refresh_observes fail fast via _check_live() with SessionClosedError instead of waiting out a timeout. Callers that never start a reader are unaffected. Refs QuiteYellow/SmartThings-Local#37
2026-08-14 17:33:13 +01:00
parent d4aebebca4
commit 7a74a955f3
2 changed files with 233 additions and 11 deletions
@@ -0,0 +1,173 @@
+"""Reader-thread death visibility (QuiteYellow/SmartThings-Local#37).
+
+A connected UDP socket surfaces ICMP errors on recv; before this the
+reader exited silently on the first one and every later request waited
+out its full timeout against a session nobody was reading. These tests
+pin the three behaviours that fixed it: advisory ICMP errnos keep the
+reader alive, a real socket error exits with a WARNING and clears
+_reader_running, and callers then fail fast with SessionClosedError.
+"""
+import errno
+import logging
+import socket
+import threading
+import time
+
+import pytest
+from OpenSSL import SSL
+
+from smartthings_local.errors import SessionClosedError
+from smartthings_local.protocol.dtls_session import DtlsCoapSession
+
+_LOGGER_NAME = "smartthings_local.protocol.dtls_session"
+
+
+class _NullAuth:
+    """Structural AuthenticationProvider — never configured, we skip connect()."""
+
+    def configure_context(self, _context):
+        return None
+
+
+class _FakeConn:
+    """Minimal stand-in for SSL.Connection: each datagram written to the
+    BIO surfaces as one decrypted packet on the next recv(), then
+    WantReadError like a drained DTLS record buffer."""
+
+    def __init__(self):
+        self._decrypted = []
+
+    def bio_write(self, datagram):
+        self._decrypted.append(datagram)
+
+    def recv(self, _n):
+        if self._decrypted:
+            return self._decrypted.pop(0)
+        raise SSL.WantReadError()
+
+    def bio_read(self, _n):
+        return b""
+
+    def send(self, _datagram):
+        return None
+
+    def shutdown(self):
+        return None
+
+
+class _FakeSock:
+    """Scripted UDP socket. Each step is bytes to return, an exception to
+    raise, or a callable to run (then a timeout, so the loop re-checks
+    _stop). An exhausted script blocks like a real recv timeout; once
+    close()d it raises EBADF the way a closed fd does."""
+
+    def __init__(self, steps=()):
+        self._steps = list(steps)
+        self.closed = False
+        self.timeout = None
+
+    def settimeout(self, value):
+        self.timeout = value
+
+    def recv(self, _n):
+        if self.closed:
+            raise OSError(errno.EBADF, "bad file descriptor")
+        if self._steps:
+            step = self._steps.pop(0)
+            if callable(step):
+                step()
+                raise socket.timeout()
+            if isinstance(step, BaseException):
+                raise step
+            return step
+        time.sleep(0.01)
+        raise socket.timeout()
+
+    def send(self, data):
+        return len(data)
+
+    def close(self):
+        self.closed = True
+
+
+def _make_session():
+    sess = DtlsCoapSession("host", 1234, auth=_NullAuth())
+    sess.conn = _FakeConn()
+    return sess
+
+
+def _run_reader(sess, steps, timeout=2.0):
+    sess.sock = _FakeSock(steps)
+    sess.start_reader()
+    sess._reader_thread.join(timeout)
+    assert not sess._reader_thread.is_alive(), "reader thread did not exit"
+
+
+def test_advisory_icmp_error_does_not_kill_reader(caplog):
+    sess = _make_session()
+    dispatched = []
+    sess._dispatch_coap = dispatched.append
+
+    with caplog.at_level(logging.DEBUG, logger=_LOGGER_NAME):
+        _run_reader(sess, [
+            OSError(errno.ECONNREFUSED, "connection refused"),
+            b"\x60\x00\x00\x00",              # survives, gets dispatched
+            lambda: sess._stop.set(),         # end the loop cleanly
+        ])
+
+    assert dispatched == [b"\x60\x00\x00\x00"]
+    assert not sess._reader_running.is_set()
+    assert any(r.levelno == logging.DEBUG and "advisory" in r.getMessage()
+               for r in caplog.records)
+    # An advisory errno is not a real exit — no WARNING.
+    assert not any(r.levelno >= logging.WARNING for r in caplog.records)
+
+
+def test_fatal_socket_error_exits_with_warning(caplog):
+    sess = _make_session()
+
+    with caplog.at_level(logging.WARNING, logger=_LOGGER_NAME):
+        _run_reader(sess, [OSError(errno.EBADF, "bad file descriptor")])
+
+    assert not sess._reader_running.is_set()
+    warnings = [r for r in caplog.records if r.levelno == logging.WARNING]
+    assert len(warnings) == 1
+    assert "reader exiting" in warnings[0].getMessage()
+
+
+def test_request_fails_fast_after_reader_death():
+    sess = _make_session()
+    _run_reader(sess, [OSError(errno.EBADF, "bad file descriptor")])
+    assert not sess._reader_running.is_set()
+
+    start = time.monotonic()
+    with pytest.raises(SessionClosedError):
+        sess.get(["oic", "d"], timeout=10.0)
+    elapsed = time.monotonic() - start
+    # The whole point: no waiting out the request timeout.
+    assert elapsed < 1.0, f"get() waited {elapsed:.2f}s instead of failing fast"
+
+
+def test_close_does_not_log_warning_on_teardown(caplog):
+    sess = _make_session()
+    sess.sock = _FakeSock()          # empty script: blocks on recv
+    sess.start_reader()
+    time.sleep(0.05)                 # let the reader reach recv
+
+    with caplog.at_level(logging.WARNING, logger=_LOGGER_NAME):
+        sess.close()
+        sess._reader_thread.join(2.0)
+
+    assert not sess._reader_thread.is_alive()
+    assert not sess._reader_running.is_set()
+    assert not any(r.levelno >= logging.WARNING for r in caplog.records)
+
+
+def test_check_live_without_reader_matches_old_conn_guard():
+    sess = _make_session()          # conn set, reader never started
+    assert sess._reader_thread is None
+    sess._check_live()              # must not raise — config-flow behaviour
+
+    sess.conn = None
+    with pytest.raises(SessionClosedError):
+        sess._check_live()