python/qmp: allow sockets to be passed to connect()

Allow existing sockets to be passed to connect(). The changes are pretty
minimal, and this allows for far greater flexibility in setting up
communications with an endpoint.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20230517163406.2593480-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/qemu/qmp/protocol.py

@@ -370,7 +370,7 @@ class AsyncProtocol(Generic[T]):
 
     @upper_half
     @require(Runstate.IDLE)
-    async def connect(self, address: SocketAddrT,
+    async def connect(self, address: Union[SocketAddrT, socket.socket],
                       ssl: Optional[SSLContext] = None) -> None:
         """
         Connect to the server and begin processing message queues.
@@ -615,7 +615,7 @@ class AsyncProtocol(Generic[T]):
         self.logger.debug("Connection accepted.")
 
     @upper_half
-    async def _do_connect(self, address: SocketAddrT,
+    async def _do_connect(self, address: Union[SocketAddrT, socket.socket],
                           ssl: Optional[SSLContext] = None) -> None:
         """
         Acting as the transport client, initiate a connection to a server.
@@ -634,9 +634,17 @@ class AsyncProtocol(Generic[T]):
         # otherwise yield.
         await asyncio.sleep(0)
 
-        self.logger.debug("Connecting to %s ...", address)
-
-        if isinstance(address, tuple):
+        if isinstance(address, socket.socket):
+            self.logger.debug("Connecting with existing socket: "
+                              "fd=%d, family=%r, type=%r",
+                              address.fileno(), address.family, address.type)
+            connect = asyncio.open_connection(
+                limit=self._limit,
+                ssl=ssl,
+                sock=address,
+            )
+        elif isinstance(address, tuple):
+            self.logger.debug("Connecting to %s ...", address)
             connect = asyncio.open_connection(
                 address[0],
                 address[1],
@@ -644,13 +652,14 @@ class AsyncProtocol(Generic[T]):
                 limit=self._limit,
             )
         else:
+            self.logger.debug("Connecting to file://%s ...", address)
             connect = asyncio.open_unix_connection(
                 path=address,
                 ssl=ssl,
                 limit=self._limit,
             )
-        self._reader, self._writer = await connect
 
+        self._reader, self._writer = await connect
         self.logger.debug("Connected.")
 
     @upper_half