added none type to return value of negotiate and changed caller handles to handle none. Added newsfragment.

libp2p/host/basic_host.py

@@ -288,6 +288,9 @@ class BasicHost(IHost):
             protocol, handler = await self.multiselect.negotiate(
                 MultiselectCommunicator(net_stream), self.negotiate_timeout
             )
+            if protocol is None:
+                await net_stream.reset()
+                raise StreamFailure("No protocol selected")
         except MultiselectError as error:
             peer_id = net_stream.muxed_conn.peer_id
             logger.debug(

libp2p/protocol_muxer/multiselect.py

@@ -53,7 +53,7 @@ class Multiselect(IMultiselectMuxer):
         self,
         communicator: IMultiselectCommunicator,
         negotiate_timeout: int = DEFAULT_NEGOTIATE_TIMEOUT,
-    ) -> tuple[TProtocol, StreamHandlerFn | None]:
+    ) -> tuple[TProtocol | None, StreamHandlerFn | None]:
         """
         Negotiate performs protocol selection.
 

libp2p/security/security_multistream.py

@@ -26,6 +26,9 @@ from libp2p.protocol_muxer.multiselect_client import (
 from libp2p.protocol_muxer.multiselect_communicator import (
     MultiselectCommunicator,
 )
+from libp2p.transport.exceptions import (
+    SecurityUpgradeFailure,
+)
 
 """
 Represents a secured connection object, which includes a connection and details about
@@ -104,7 +107,7 @@ class SecurityMultistream(ABC):
         :param is_initiator: true if we are the initiator, false otherwise
         :return: selected secure transport
         """
-        protocol: TProtocol
+        protocol: TProtocol | None
         communicator = MultiselectCommunicator(conn)
         if is_initiator:
             # Select protocol if initiator
@@ -114,5 +117,7 @@ class SecurityMultistream(ABC):
         else:
             # Select protocol if non-initiator
             protocol, _ = await self.multiselect.negotiate(communicator)
+            if protocol is None:
+                raise SecurityUpgradeFailure("No protocol selected")
         # Return transport from protocol
         return self.transports[protocol]

libp2p/stream_muxer/muxer_multistream.py

@@ -30,6 +30,9 @@ from libp2p.stream_muxer.yamux.yamux import (
     PROTOCOL_ID,
     Yamux,
 )
+from libp2p.transport.exceptions import (
+    MuxerUpgradeFailure,
+)
 
 
 class MuxerMultistream:
@@ -73,7 +76,7 @@ class MuxerMultistream:
         :param conn: conn to choose a transport over
         :return: selected muxer transport
         """
-        protocol: TProtocol
+        protocol: TProtocol | None
         communicator = MultiselectCommunicator(conn)
         if conn.is_initiator:
             protocol = await self.multiselect_client.select_one_of(
@@ -81,6 +84,8 @@ class MuxerMultistream:
             )
         else:
             protocol, _ = await self.multiselect.negotiate(communicator)
+            if protocol is None:
+                raise MuxerUpgradeFailure("No protocol selected")
         return self.transports[protocol]
 
     async def new_conn(self, conn: ISecureConn, peer_id: ID) -> IMuxedConn:

newsfragments/837.fix.rst

@@ -0,0 +1 @@
+Added multiselect type consistency in negotiate method. Updates all the usages of the method.