From: David Laight <David.Laight@xxxxxxxxxx> > From: Gilad Naaman > > Sent: 28 October 2024 12:49 > ... > > the list `net->sctp.local_addr_list` gets obscenely long. > > > > This list contains both IPv4 and IPv6 addresses, of all scopes, and it is > > a single long list, instead of a hashtable. > > > > In our case we had 12K interfaces, each with an IPv4 and 2 IPv6 addresses > > (GUA+LLA), which made deletion of a single address pretty expensive, since > > it requires a linear search through 36K addresses. > ... > > Is that the list that SCTP uses in order to pass all of its local addresses > to the remote system during connection establishment? Yes, it is exactly that list. > In which case it really makes no sense to have the list at all if it contains > more than a handful of addresses. > > Indeed the whole notion of 'send ALL my addresses' is just plain broken. > What happens in practise is that applications pretty much always have to > bind to all (typically both) the relevant addresses to stop the system > sending IP addresses that are unroutable from the remote system - and > may even refer to an entirely different local network. > > Passing this buck to the application isn't really right either. > It ought to be a property of the network topology. > But that is hard to describe. > The two systems 10.1.1.1 and 10.1.1.2 could both have private 192.168.1.x > networks (without IP forwarding) and other 10.1.1.x hosts could be > randomly connected to either network. > > David Yeah, I'm not entirely sure what should even happen in this case. I feel like I could use a CONFIG_SCTP_INIT_ADDRESS and CONFIG_SCTP_AUTO_ASCONF, where setting both to false removes this behaviour and list. Not sure if it makes sense, though.
