Re: [libvirt] [PATCHv2 2/6] event: server RPC protocol tweaks for domain lifecycle events

This patch adds some new RPC call numbers, but for ease of review, they sit idle until a later patch adds the client counterpart to drive the new RPCs. Also for ease of review, I limited this patch to just the lifecycle event; although converting the remaining 15 domain events will be quite mechanical. On the server side, we have to have a function per RPC call, largely with duplicated bodies (the key difference being that we store in our callback opaque pointer whether events should be fired with old or new style); meanwhile, a single function can drive multiple RPC messages, along with a strategic choice of XDR struct layout, makes the event generation code for both styles fairly compact. I debated about adding a tri-state witness variable per connection (values 'unknown', 'legacy', 'modern'). It would start as 'unknown', move to 'legacy' if any RPC call is made to a legacy event call, and move to 'modern' if the feature probe is made; then the event code could issue an error if the witness state is incorrect (a legacy RPC call while in 'modern', a modern RPC call while in 'unknown' or 'legacy', and a feature probe while in 'legacy' or 'modern'). But while it might prevent odd behavior caused by protocol fuzzing, I don't see that it would prevent any security holes, so I considered it bloat. * src/libvirt_internal.h (VIR_DRV_FEATURE_REMOTE_EVENT_CALLBACK): New feature. * src/remote/remote_protocol.x (REMOTE_PROC_CONNECT_DOMAIN_EVENT_CALLBACK_REGISTER_ANY) (REMOTE_PROC_CONNECT_DOMAIN_EVENT_CALLBACK_DEREGISTER_ANY) (REMOTE_PROC_DOMAIN_EVENT_CALLBACK_LIFECYCLE): New RPCs. * daemon/remote.c (daemonClientCallback): Add field. (remoteDispatchConnectDomainEventCallbackRegisterAny) (remoteDispatchConnectDomainEventCallbackDeregisterAny): New functions. (remoteDispatchConnectDomainEventRegisterAny) (remoteDispatchConnectDomainEventDeregisterAny): Mark legacy use. (remoteRelayDomainEventLifecycle): Change message based on legacy or new use. (remoteDispatchConnectSupportsFeature): Advertise new feature. * src/remote_protocol-structs: Regenerate. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- daemon/remote.c | 173 ++++++++++++++++++++++++++++++++++++++++--- src/libvirt_internal.h | 7 +- src/remote/remote_protocol.x | 39 +++++++++- src/remote_protocol-structs | 17 +++++ 4 files changed, 225 insertions(+), 11 deletions(-)

@@ -5068,5 +5085,25 @@ enum remote_procedure { * @generate: both * @acl: none */ - REMOTE_PROC_NETWORK_EVENT_LIFECYCLE = 315 + REMOTE_PROC_NETWORK_EVENT_LIFECYCLE = 315, + + /** + * @generate: none + * @priority: high + * @acl: none + */ + REMOTE_PROC_CONNECT_DOMAIN_EVENT_CALLBACK_REGISTER_ANY = 316, + + /** + * @generate: none + * @priority: high + * @acl: none + */ + REMOTE_PROC_CONNECT_DOMAIN_EVENT_CALLBACK_DEREGISTER_ANY = 317,