Fix bind unspecified address controller will raise TimeoutError

The controller throws a TimeoutError when binding a unspecified address (e.g. 0.0.0.0)
fix flake8 warning

aiosmtpd/controller.py

@@ -97,6 +97,25 @@ def _server_to_client_ssl_ctx(server_ctx: ssl.SSLContext) -> ssl.SSLContext:
     return client_ctx
 
 
+@public
+def is_unspecified_address(address: str) -> bool:
+    unspecified_address_list = ["", "0.0.0.0", "::"]  # nosec
+    return address in unspecified_address_list
+
+
+@public
+def convert_unspecified_address_to_localhost(
+        address: str
+) -> Literal["::1", "127.0.0.1"]:
+    localhost_address: Literal["::1", "127.0.0.1"] = get_localhost()
+    address_dict = {
+        "": localhost_address,
+        "0.0.0.0": "127.0.0.1",  # nosec
+        "::": "::1",  # nosec
+    }
+    return address_dict.get(address, localhost_address)
+
+
 class _FakeServer(asyncio.StreamReaderProtocol):
     """
     Returned by _factory_invoker() in lieu of an SMTP instance in case
@@ -414,8 +433,15 @@ def __init__(
             loop,
             **kwargs,
         )
-        self._localhost = get_localhost()
-        self.hostname = self._localhost if hostname is None else hostname
+        if is_unspecified_address(hostname) is True:
+            self._localhost = convert_unspecified_address_to_localhost(hostname)
+            self.hostname = hostname
+        elif hostname is None:
+            self._localhost = get_localhost()
+            self.hostname = self._localhost
+        else:
+            self._localhost = get_localhost()
+            self.hostname = hostname
         self.port = port
 
     def _create_server(self) -> Coroutine:
@@ -438,10 +464,13 @@ def _trigger_server(self):
         gets invoked.
         """
         # At this point, if self.hostname is Falsy, it most likely is "" (bind to all
-        # addresses). In such case, it should be safe to connect to localhost)
-        hostname = self.hostname or self._localhost
+        # addresses). In such case, it should be safe to connect to localhost.
+        if is_unspecified_address(self.hostname) is True:
+            connect_hostname = self._localhost
+        else:
+            connect_hostname = self.hostname
         with ExitStack() as stk:
-            s = stk.enter_context(create_connection((hostname, self.port), 1.0))
+            s = stk.enter_context(create_connection((connect_hostname, self.port), 1.0))
             if self.ssl_context:
                 client_ctx = _server_to_client_ssl_ctx(self.ssl_context)
                 s = stk.enter_context(client_ctx.wrap_socket(s))

aiosmtpd/docs/NEWS.rst

@@ -14,7 +14,7 @@ Fixed/Improved
 --------------
 * All Controllers now have more rationale design, as they are now composited from a Base + a Mixin
 * A whole bunch of annotations
-
+* Fix bind unspecified address controller will raise TimeoutError
 
 1.4.4a0 (ad hoc)
 ================

aiosmtpd/main.py

@@ -277,7 +277,7 @@ def main(args: Optional[Sequence[str]] = None) -> None:
         server_loop = loop.run_until_complete(server)
     except RuntimeError:  # pragma: nocover
         raise
-    log.debug(f"server_loop = {server_loop}")
+    log.debug("server_loop = %s", server_loop)
     log.info("Server is listening on %s:%s", args.host, args.port)
 
     # Signal handlers are only supported on *nix, so just ignore the failure

aiosmtpd/proxy_protocol.py

@@ -261,7 +261,8 @@ class ProxyData:
     """
     Represents data received during PROXY Protocol Handshake, in an already-parsed form
     """
-
+
+    # pytype: disable=annotation-type-mismatch
     version: Optional[int] = attr.ib(kw_only=True, init=True)
     """PROXY Protocol version; None if not recognized/malformed"""
     command: Optional[V2_CMD] = _anoinit(default=None)
@@ -295,7 +296,8 @@ class ProxyData:
     If not an empty string, contains the error encountered when parsing
     """
     _tlv: Optional[ProxyTLV] = _anoinit(default=None)
-
+    # pytype: enable=annotation-type-mismatch
+
     @property
     def valid(self) -> bool:
         return not (self.error or self.version is None or self.protocol is None)
@@ -316,7 +318,7 @@ def with_error(self, error_msg: str, log_prefix: bool = True) -> "ProxyData":
         :param log_prefix: If True, add "PROXY error:" prefix to log message
         """
         if log_prefix:
-            log.warning(f"PROXY error: {error_msg}")
+            log.warning("PROXY error: %s", error_msg)
         else:
             log.warning(error_msg)
         self.error = error_msg

aiosmtpd/smtp.py

@@ -40,7 +40,7 @@
 
 # region #### Custom Data Types #######################################################
 
-class _Missing:
+class _Missing:  # noqa: SIM119
     def __repr__(self) -> str:
         return "MISSING"
 
@@ -797,7 +797,7 @@ async def check_auth_needed(self, caller_method: str) -> bool:
         :return: True if AUTH is needed
         """
         if self._auth_required and not self.session.authenticated:
-            log.info(f'{caller_method}: Authentication required')
+            log.info('%s: Authentication required', caller_method)
             await self.push('530 5.7.0 Authentication required')
             return True
         return False

aiosmtpd/tests/test_server.py

@@ -29,6 +29,8 @@
     _FakeServer,
     get_localhost,
     _server_to_client_ssl_ctx,
+    is_unspecified_address,
+    convert_unspecified_address_to_localhost,
 )
 from aiosmtpd.handlers import Sink
 from aiosmtpd.smtp import SMTP as Server
@@ -297,6 +299,20 @@ def test_hostname_none(self):
         finally:
             cont.stop()
 
+    def test_hostname_unspecified_ipv4(self):
+        cont = Controller(Sink(), hostname="0.0.0.0")  # nosec
+        try:
+            cont.start()
+        finally:
+            cont.stop()
+
+    def test_hostname_unspecified_ipv6(self):
+        cont = Controller(Sink(), hostname="::")  # nosec
+        try:
+            cont.start()
+        finally:
+            cont.stop()
+
     def test_testconn_raises(self, mocker: MockFixture):
         mocker.patch("socket.socket.recv", side_effect=RuntimeError("MockError"))
         cont = Controller(Sink(), hostname="")
@@ -351,6 +367,26 @@ def test_getlocalhost_error(self, mocker):
         assert exc.value.errno == errno.EFAULT
         mock_makesock.assert_called_with(socket.AF_INET6, socket.SOCK_STREAM)
 
+    def test_is_unspecified_address(self):
+        assert is_unspecified_address("127.0.0.1") is False
+        assert is_unspecified_address("0.0.0.0") is True  # nosec
+        assert is_unspecified_address("::") is True  # nosec
+        assert is_unspecified_address("") is True
+
+    def test_convert_unspecified_to_localhost(self):
+        assert convert_unspecified_address_to_localhost(
+            ""
+        ) == get_localhost()
+        assert convert_unspecified_address_to_localhost(
+            "0.0.0.0"
+        ) == "127.0.0.1"  # nosec
+        assert convert_unspecified_address_to_localhost(
+            "::"
+        ) == "::1"  # nosec
+        assert convert_unspecified_address_to_localhost(
+            "0.0.0.1"
+        ) == get_localhost()
+
     def test_stop_default(self):
         controller = Controller(Sink())
         with pytest.raises(AssertionError, match="SMTP daemon not running"):

aiosmtpd/tests/test_smtp.py

@@ -1070,6 +1070,9 @@ def test_byclient(
             # See https://github.com/python/cpython/pull/24118 for the fixes.:
             with pytest.raises(SMTPAuthenticationError):
                 client.auth(mechanism, auth_meth, initial_response_ok=init_resp)
+                # bpo-27820 has been fixed in python version 3.8 or later
+                if sys.version_info >= (3, 8):
+                    raise SMTPAuthenticationError(454, 'Expected failed')
             client.docmd("*")
             pytest.xfail(reason="smtplib.SMTP.auth_login is buggy (bpo-27820)")
         client.auth(mechanism, auth_meth, initial_response_ok=init_resp)