fix: handle asynchronous QMP events before greeting

hydra/qmp.py

@@ -23,6 +23,12 @@ class QMPClient:
             self.socket.settimeout(timeout)
             self.socket.connect(str(path))
             greeting = self._receive(deadline)
+            # Real QEMU can queue a SPICE event across monitor reconnects.
+            # Consume only protocol events, retaining the original deadline.
+            while 'event' in greeting:
+                if not self._async_event(greeting):
+                    raise QMPError('Invalid QMP event before greeting')
+                greeting = self._receive(deadline)
             if not isinstance(greeting.get('QMP'), dict):
                 raise QMPError('Invalid QMP greeting')
             self._command('qmp_capabilities', None, deadline)
@@ -32,6 +38,22 @@ class QMPClient:
                 raise
             raise QMPError(f'QMP connection failed: {exc}') from exc
 
+    @staticmethod
+    def _async_event(message: dict) -> bool:
+        if not {'event', 'timestamp'} <= message.keys() <= {'event', 'timestamp', 'data'}:
+            return False
+        if not isinstance(message['event'], str) or not message['event']:
+            return False
+        if 'data' in message and not isinstance(message['data'], dict):
+            return False
+        stamp = message['timestamp']
+        if (not isinstance(stamp, dict) or set(stamp) != {'seconds', 'microseconds'}
+                or any(type(value) is not int for value in stamp.values())):
+            return False
+        seconds, micros = stamp['seconds'], stamp['microseconds']
+        # QMP specifies (-1, -1) when the server cannot retrieve host time.
+        return (seconds == -1 and micros == -1) or (seconds >= 0 and 0 <= micros < 1000000)
+
     def _receive(self, deadline: float) -> dict:
         while True:
             remaining = deadline - time.monotonic()