Here we clean up internal uses of type discover.node, converting most code to use
enode.Node instead. The discover.node type used to be the canonical representation of
network hosts before ENR was introduced. Most code worked with *node to avoid conversions
when interacting with Table methods. Since *node also contains internal state of Table and
is a mutable type, using *node outside of Table code is prone to data races. It's also
cleaner not having to wrap/unwrap *enode.Node all the time.
discover.node has been renamed to tableNode to clarify its purpose.
While here, we also change most uses of net.UDPAddr into netip.AddrPort. While this is
technically a separate refactoring from the *node -> *enode.Node change, it is more
convenient because *enode.Node handles IP addresses as netip.Addr. The switch to package
netip in discovery would've happened very soon anyway.
The change to netip.AddrPort stops at certain interface points. For example, since package
p2p/netutil has not been converted to use netip.Addr yet, we still have to convert to
net.IP/net.UDPAddr in a few places.
It seems the semantic differences between addFoundNode and addInboundNode were lost in
#29572. My understanding is addFoundNode is for a node you have not contacted directly
(and are unsure if is available) whereas addInboundNode is for adding nodes that have
contacted the local node and we can verify they are active.
handleAddNode seems to be the consolidation of those two methods, yet it bumps the node in
the bucket (updating it's IP addr) even if the node was not an inbound. This PR fixes
this. It wasn't originally caught in tests like TestTable_addSeenNode because the
manipulation of the node object actually modified the node value used by the test.
New logic is added to reject non-inbound updates unless the sequence number of the
(signed) ENR increases. Inbound updates, which are published by the updated node itself,
are always accepted. If an inbound update changes the endpoint, the node will be
revalidated on an expedited schedule.
Co-authored-by: Felix Lange <fjl@twurst.com>
In #29572, I assumed the revalidation list that the node is contained in could only ever
be changed by the outcome of a revalidation request. But turns out that's not true: if the
node gets removed due to FINDNODE failure, it will also be removed from the list it is in.
This causes a crash.
The invariant is: while node is in table, it is always in exactly one of the two lists. So
it seems best to store a pointer to the current list within the node itself.
