p2p, p2p/discover: add signed ENR generation (#17753)

This PR adds enode.LocalNode and integrates it into the p2p
subsystem. This new object is the keeper of the local node
record. For now, a new version of the record is produced every
time the client restarts. We'll make it smarter to avoid that in
the future.

There are a couple of other changes in this commit: discovery now
waits for all of its goroutines at shutdown and the p2p server
now closes the node database after discovery has shut down. This
fixes a leveldb crash in tests. p2p server startup is faster
because it doesn't need to wait for the external IP query
anymore.

1 files changed, 6 insertions, 4 deletions

diff --git a/p2p/protocol.go b/p2p/protocol.go
index 4b90a2a70..9438ab8e4 100644
--- a/p2p/protocol.go
+++ b/p2p/protocol.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/enr"
 )
 
 // Protocol represents a P2P subprotocol implementation.
@@ -52,6 +53,9 @@ type Protocol struct {
 	// about a certain peer in the network. If an info retrieval function is set,
 	// but returns nil, it is assumed that the protocol handshake is still running.
 	PeerInfo func(id enode.ID) interface{}
+
+	// Attributes contains protocol specific information for the node record.
+	Attributes []enr.Entry
 }
 
 func (p Protocol) cap() Cap {
@@ -64,10 +68,6 @@ type Cap struct {
 	Version uint
 }
 
-func (cap Cap) RlpData() interface{} {
-	return []interface{}{cap.Name, cap.Version}
-}
-
 func (cap Cap) String() string {
 	return fmt.Sprintf("%s/%d", cap.Name, cap.Version)
 }
@@ -79,3 +79,5 @@ func (cs capsByNameAndVersion) Swap(i, j int) { cs[i], cs[j] = cs[j], cs[i] }
 func (cs capsByNameAndVersion) Less(i, j int) bool {
 	return cs[i].Name < cs[j].Name || (cs[i].Name == cs[j].Name && cs[i].Version < cs[j].Version)
 }
+
+func (capsByNameAndVersion) ENRKey() string { return "cap" }