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.

2 files changed, 7 insertions, 13 deletions

diff --git a/p2p/nat/nat.go b/p2p/nat/nat.go
index a254648c6..8fad921c4 100644
--- a/p2p/nat/nat.go
+++ b/p2p/nat/nat.go
@@ -129,21 +129,15 @@ func Map(m Interface, c chan struct{}, protocol string, extport, intport int, na
 // ExtIP assumes that the local machine is reachable on the given
 // external IP address, and that any required ports were mapped manually.
 // Mapping operations will not return an error but won't actually do anything.
-func ExtIP(ip net.IP) Interface {
-	if ip == nil {
-		panic("IP must not be nil")
-	}
-	return extIP(ip)
-}
+type ExtIP net.IP
 
-type extIP net.IP
-
-func (n extIP) ExternalIP() (net.IP, error) { return net.IP(n), nil }
-func (n extIP) String() string              { return fmt.Sprintf("ExtIP(%v)", net.IP(n)) }
+func (n ExtIP) ExternalIP() (net.IP, error) { return net.IP(n), nil }
+func (n ExtIP) String() string              { return fmt.Sprintf("ExtIP(%v)", net.IP(n)) }
 
 // These do nothing.
-func (extIP) AddMapping(string, int, int, string, time.Duration) error { return nil }
-func (extIP) DeleteMapping(string, int, int) error                     { return nil }
+
+func (ExtIP) AddMapping(string, int, int, string, time.Duration) error { return nil }
+func (ExtIP) DeleteMapping(string, int, int) error                     { return nil }
 
 // Any returns a port mapper that tries to discover any supported
 // mechanism on the local network.
diff --git a/p2p/nat/nat_test.go b/p2p/nat/nat_test.go
index 469101e99..814e6d9e1 100644
--- a/p2p/nat/nat_test.go
+++ b/p2p/nat/nat_test.go
@@ -28,7 +28,7 @@ import (
 func TestAutoDiscRace(t *testing.T) {
 	ad := startautodisc("thing", func() Interface {
 		time.Sleep(500 * time.Millisecond)
-		return extIP{33, 44, 55, 66}
+		return ExtIP{33, 44, 55, 66}
 	})
 
 	// Spawn a few concurrent calls to ad.ExternalIP.