rpc: Add admin_addTrustedPeer and admin_removeTrustedPeer.

These RPC calls are analogous to Parity's parity_addReservedPeer and
parity_removeReservedPeer.

They are useful for adjusting the trusted peer set during runtime,
without requiring restarting the server.

internal/web3ext/web3ext.go

@@ -123,6 +123,16 @@ web3._extend({
 			call: 'admin_removePeer',
 			params: 1
 		}),
+		new web3._extend.Method({
+			name: 'addTrustedPeer',
+			call: 'admin_addTrustedPeer',
+			params: 1
+		}),
+		new web3._extend.Method({
+			name: 'removeTrustedPeer',
+			call: 'admin_removeTrustedPeer',
+			params: 1
+		}),
 		new web3._extend.Method({
 			name: 'exportChain',
 			call: 'admin_exportChain',

node/api.go

@@ -59,7 +59,7 @@ func (api *PrivateAdminAPI) AddPeer(url string) (bool, error) {
 	return true, nil
 }
 
-// RemovePeer disconnects from a a remote node if the connection exists
+// RemovePeer disconnects from a remote node if the connection exists
 func (api *PrivateAdminAPI) RemovePeer(url string) (bool, error) {
 	// Make sure the server is running, fail otherwise
 	server := api.node.Server()
@@ -75,6 +75,37 @@ func (api *PrivateAdminAPI) RemovePeer(url string) (bool, error) {
 	return true, nil
 }
 
+// AddTrustedPeer allows a remote node to always connect, even if slots are full
+func (api *PrivateAdminAPI) AddTrustedPeer(url string) (bool, error) {
+	// Make sure the server is running, fail otherwise
+	server := api.node.Server()
+	if server == nil {
+		return false, ErrNodeStopped
+	}
+	node, err := discover.ParseNode(url)
+	if err != nil {
+		return false, fmt.Errorf("invalid enode: %v", err)
+	}
+	server.AddTrustedPeer(node)
+	return true, nil
+}
+
+// RemoveTrustedPeer removes a remote node from the trusted peer set, but it
+// does not disconnect it automatically.
+func (api *PrivateAdminAPI) RemoveTrustedPeer(url string) (bool, error) {
+	// Make sure the server is running, fail otherwise
+	server := api.node.Server()
+	if server == nil {
+		return false, ErrNodeStopped
+	}
+	node, err := discover.ParseNode(url)
+	if err != nil {
+		return false, fmt.Errorf("invalid enode: %v", err)
+	}
+	server.RemoveTrustedPeer(node)
+	return true, nil
+}
+
 // PeerEvents creates an RPC subscription which receives peer events from the
 // node's p2p.Server
 func (api *PrivateAdminAPI) PeerEvents(ctx context.Context) (*rpc.Subscription, error) {

p2p/server.go

@@ -169,6 +169,8 @@ type Server struct {
 	quit          chan struct{}
 	addstatic     chan *discover.Node
 	removestatic  chan *discover.Node
+	addtrusted    chan *discover.Node
+	removetrusted chan *discover.Node
 	posthandshake chan *conn
 	addpeer       chan *conn
 	delpeer       chan peerDrop
@@ -300,6 +302,23 @@ func (srv *Server) RemovePeer(node *discover.Node) {
 	}
 }
 
+// AddTrustedPeer adds the given node to a reserved whitelist which allows the
+// node to always connect, even if the slot are full.
+func (srv *Server) AddTrustedPeer(node *discover.Node) {
+	select {
+	case srv.addtrusted <- node:
+	case <-srv.quit:
+	}
+}
+
+// RemoveTrustedPeer removes the given node from the trusted peer set.
+func (srv *Server) RemoveTrustedPeer(node *discover.Node) {
+	select {
+	case srv.removetrusted <- node:
+	case <-srv.quit:
+	}
+}
+
 // SubscribePeers subscribes the given channel to peer events
 func (srv *Server) SubscribeEvents(ch chan *PeerEvent) event.Subscription {
 	return srv.peerFeed.Subscribe(ch)
@@ -410,6 +429,8 @@ func (srv *Server) Start() (err error) {
 	srv.posthandshake = make(chan *conn)
 	srv.addstatic = make(chan *discover.Node)
 	srv.removestatic = make(chan *discover.Node)
+	srv.addtrusted = make(chan *discover.Node)
+	srv.removetrusted = make(chan *discover.Node)
 	srv.peerOp = make(chan peerOpFunc)
 	srv.peerOpDone = make(chan struct{})
 
@@ -546,8 +567,7 @@ func (srv *Server) run(dialstate dialer) {
 		queuedTasks  []task // tasks that can't run yet
 	)
 	// Put trusted nodes into a map to speed up checks.
-	// Trusted peers are loaded on startup and cannot be
+	// Trusted peers are loaded on startup or added via AddTrustedPeer RPC.
-	// modified while the server is running.
 	for _, n := range srv.TrustedNodes {
 		trusted[n.ID] = true
 	}
@@ -599,12 +619,32 @@ running:
 		case n := <-srv.removestatic:
 			// This channel is used by RemovePeer to send a
 			// disconnect request to a peer and begin the
-			// stop keeping the node connected
+			// stop keeping the node connected.
 			srv.log.Trace("Removing static node", "node", n)
 			dialstate.removeStatic(n)
 			if p, ok := peers[n.ID]; ok {
 				p.Disconnect(DiscRequested)
 			}
+		case n := <-srv.addtrusted:
+			// This channel is used by AddTrustedPeer to add an enode
+			// to the trusted node set.
+			srv.log.Trace("Adding trusted node", "node", n)
+			trusted[n.ID] = true
+			// Mark any already-connected peer as trusted
+			if p, ok := peers[n.ID]; ok {
+				p.rw.flags |= trustedConn
+			}
+		case n := <-srv.removetrusted:
+			// This channel is used by RemoveTrustedPeer to remove an enode
+			// from the trusted node set.
+			srv.log.Trace("Removing trusted node", "node", n)
+			if _, ok := trusted[n.ID]; ok {
+				delete(trusted, n.ID)
+			}
+			// Unmark any already-connected peer as trusted
+			if p, ok := peers[n.ID]; ok {
+				p.rw.flags &= ^trustedConn
+			}
 		case op := <-srv.peerOp:
 			// This channel is used by Peers and PeerCount.
 			op(peers)