tools: ynl: support listening on all nsids

A new method ntf_listen_all_nsid() to enable listening on events from
all namespaces.  Useful for testing cross-namespace functionality.

recv() replaced with recvmsg() to be able to receive NSID through the
ancillary data.

Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Link: https://patch.msgid.link/20260520172317.175168-4-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/pyynl/lib/ynl.py

@@ -42,6 +42,7 @@ class Netlink:
     SOL_NETLINK = 270
 
     NETLINK_ADD_MEMBERSHIP = 1
+    NETLINK_LISTEN_ALL_NSID = 8
     NETLINK_CAP_ACK = 10
     NETLINK_EXT_ACK = 11
     NETLINK_GET_STRICT_CHK = 12
@@ -680,6 +681,7 @@ class YnlFamily(SpecFamily):
     Notification API:
 
       ynl.ntf_subscribe(mcast_name)      -- join a multicast group
+      ynl.ntf_listen_all_nsid()          -- listen on all netns
       ynl.check_ntf()                    -- drain pending notifications
       ynl.poll_ntf(duration=None)        -- yield notifications
 
@@ -748,6 +750,23 @@ class YnlFamily(SpecFamily):
         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP,
                              mcast_id)
 
+    def ntf_listen_all_nsid(self):
+        """Enable NETLINK_LISTEN_ALL_NSID to receive notifications from all
+        namespaces that have an nsid mapped in the current one."""
+        self.sock.setsockopt(Netlink.SOL_NETLINK,
+                             Netlink.NETLINK_LISTEN_ALL_NSID, 1)
+
+    @staticmethod
+    def _decode_nsid(ancdata):
+        for cmsg_level, cmsg_type, cmsg_data in ancdata:
+            if (cmsg_level == Netlink.SOL_NETLINK and
+                    cmsg_type == Netlink.NETLINK_LISTEN_ALL_NSID):
+                nsid = struct.unpack('i', cmsg_data)[0]
+                if nsid >= 0:
+                    return nsid
+                return None
+        return None
+
     def set_recv_dbg(self, enabled):
         self._recv_dbg = enabled
 
@@ -1235,7 +1254,7 @@ class YnlFamily(SpecFamily):
                             f" when parsing '{attr_spec['name']}'")
         return raw
 
-    def handle_ntf(self, decoded):
+    def handle_ntf(self, decoded, nsid=None):
         msg = {}
         if self.include_raw:
             msg['raw'] = decoded
@@ -1246,15 +1265,22 @@ class YnlFamily(SpecFamily):
 
         msg['name'] = op['name']
         msg['msg'] = attrs
+        if nsid is not None:
+            msg['nsid'] = nsid
         self.async_msg_queue.put(msg)
 
+    def _recvmsg(self, flags=0):
+        reply, ancdata, _, _ = self.sock.recvmsg(self._recv_size, 4096, flags)
+        return reply, ancdata
+
     def check_ntf(self):
         while True:
             try:
-                reply = self.sock.recv(self._recv_size, socket.MSG_DONTWAIT)
+                reply, ancdata = self._recvmsg(socket.MSG_DONTWAIT)
             except BlockingIOError:
                 return
 
+            nsid = self._decode_nsid(ancdata)
             nms = NlMsgs(reply)
             self._recv_dbg_print(reply, nms)
             for nl_msg in nms:
@@ -1271,7 +1297,7 @@ class YnlFamily(SpecFamily):
                     print("Unexpected msg id while checking for ntf", decoded)
                     continue
 
-                self.handle_ntf(decoded)
+                self.handle_ntf(decoded, nsid)
 
     def poll_ntf(self, duration=None):
         start_time = time.time()
@@ -1335,7 +1361,8 @@ class YnlFamily(SpecFamily):
         rsp = []
         op_rsp = []
         while not done:
-            reply = self.sock.recv(self._recv_size)
+            reply, ancdata = self._recvmsg()
+            nsid = self._decode_nsid(ancdata)
             nms = NlMsgs(reply)
             self._recv_dbg_print(reply, nms)
             for nl_msg in nms:
@@ -1374,7 +1401,7 @@ class YnlFamily(SpecFamily):
                 # Check if this is a reply to our request
                 if nl_msg.nl_seq not in reqs_by_seq or decoded.cmd() != op.rsp_value:
                     if decoded.cmd() in self.async_msg_ids:
-                        self.handle_ntf(decoded)
+                        self.handle_ntf(decoded, nsid)
                         continue
                     print('Unexpected message: ' + repr(decoded))
                     continue