cmd/geth, cmd/mist, cmd/utils, eth, p2p: support trusted peers

8 files changed, 146 insertions, 27 deletions

diff --git a/cmd/geth/admin.go b/cmd/geth/admin.go
index 31f8d4400..a07e694de 100644
--- a/cmd/geth/admin.go
+++ b/cmd/geth/admin.go
@@ -25,7 +25,7 @@ func (js *jsre) adminBindings() {
 	js.re.Set("admin", struct{}{})
 	t, _ := js.re.Get("admin")
 	admin := t.Object()
-	admin.Set("suggestPeer", js.suggestPeer)
+	admin.Set("trustPeer", js.trustPeer)
 	admin.Set("startRPC", js.startRPC)
 	admin.Set("stopRPC", js.stopRPC)
 	admin.Set("nodeInfo", js.nodeInfo)
@@ -243,13 +243,13 @@ func (js *jsre) stopRPC(call otto.FunctionCall) otto.Value {
 	return otto.FalseValue()
 }
 
-func (js *jsre) suggestPeer(call otto.FunctionCall) otto.Value {
+func (js *jsre) trustPeer(call otto.FunctionCall) otto.Value {
 	nodeURL, err := call.Argument(0).ToString()
 	if err != nil {
 		fmt.Println(err)
 		return otto.FalseValue()
 	}
-	err = js.ethereum.SuggestPeer(nodeURL)
+	err = js.ethereum.TrustPeer(nodeURL)
 	if err != nil {
 		fmt.Println(err)
 		return otto.FalseValue()
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index ef007051c..d9d1c1b15 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -232,7 +232,8 @@ JavaScript API. See https://github.com/ethereum/go-ethereum/wiki/Javascipt-Conso
 		utils.IdentityFlag,
 		utils.UnlockedAccountFlag,
 		utils.PasswordFileFlag,
-		utils.BootnodesFlag,
+		utils.BootNodesFlag,
+		utils.TrustedNodesFlag,
 		utils.DataDirFlag,
 		utils.BlockchainVersionFlag,
 		utils.JSpathFlag,
diff --git a/cmd/mist/main.go b/cmd/mist/main.go
index 1030d6ada..18fb919b4 100644
--- a/cmd/mist/main.go
+++ b/cmd/mist/main.go
@@ -69,7 +69,7 @@ func init() {
 		assetPathFlag,
 		rpcCorsFlag,
 
-		utils.BootnodesFlag,
+		utils.BootNodesFlag,
 		utils.DataDirFlag,
 		utils.ListenPortFlag,
 		utils.LogFileFlag,
diff --git a/cmd/mist/ui_lib.go b/cmd/mist/ui_lib.go
index 34ce56e77..e1a3aa254 100644
--- a/cmd/mist/ui_lib.go
+++ b/cmd/mist/ui_lib.go
@@ -104,8 +104,8 @@ func (ui *UiLib) Connect(button qml.Object) {
 }
 
 func (ui *UiLib) ConnectToPeer(nodeURL string) {
-	if err := ui.eth.SuggestPeer(nodeURL); err != nil {
-		guilogger.Infoln("SuggestPeer error: " + err.Error())
+	if err := ui.eth.TrustPeer(nodeURL); err != nil {
+		guilogger.Infoln("TrustPeer error: " + err.Error())
 	}
 }
 
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index c013510d8..f52bfc21f 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -202,11 +202,16 @@ var (
 		Usage: "Network listening port",
 		Value: 30303,
 	}
-	BootnodesFlag = cli.StringFlag{
+	BootNodesFlag = cli.StringFlag{
 		Name:  "bootnodes",
 		Usage: "Space-separated enode URLs for p2p discovery bootstrap",
 		Value: "",
 	}
+	TrustedNodesFlag = cli.StringFlag{
+		Name:  "trustednodes",
+		Usage: "List of trusted nodes (either an enode list or path to a json file of enodes)",
+		Value: "",
+	}
 	NodeKeyFileFlag = cli.StringFlag{
 		Name:  "nodekey",
 		Usage: "P2P node key file",
@@ -292,7 +297,8 @@ func MakeEthConfig(clientID, version string, ctx *cli.Context) *eth.Config {
 		NodeKey:            GetNodeKey(ctx),
 		Shh:                ctx.GlobalBool(WhisperEnabledFlag.Name),
 		Dial:               true,
-		BootNodes:          ctx.GlobalString(BootnodesFlag.Name),
+		BootNodes:          ctx.GlobalString(BootNodesFlag.Name),
+		TrustedNodes:       ctx.GlobalString(TrustedNodesFlag.Name),
 	}
 }
 
diff --git a/eth/backend.go b/eth/backend.go
index c5fa328b0..f8d57c985 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -2,7 +2,10 @@ package eth
 
 import (
 	"crypto/ecdsa"
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path"
 	"strings"
 	"time"
@@ -56,10 +59,13 @@ type Config struct {
 	MaxPeers int
 	Port     string
 
-	// This should be a space-separated list of
-	// discovery node URLs.
+	// Space-separated list of discovery node URLs
 	BootNodes string
 
+	// Either a space-separated list of discovery node URLs, or a path to a json
+	// file containing such a list.
+	TrustedNodes string
+
 	// This key is used to identify the node on the network.
 	// If nil, an ephemeral key is used.
 	NodeKey *ecdsa.PrivateKey
@@ -96,6 +102,46 @@ func (cfg *Config) parseBootNodes() []*discover.Node {
 	return ns
 }
 
+// parseTrustedNodes parses a list of discovery node URLs either given literally,
+// or loaded from a .json file.
+func (cfg *Config) parseTrustedNodes() []*discover.Node {
+	// Short circuit if no trusted nodes were given
+	if cfg.TrustedNodes == "" {
+		return nil
+	}
+	// Try to interpret the trusted node config as a .json file
+	if _, err := os.Stat(cfg.TrustedNodes); err == nil {
+		// Load the file from disk
+		blob, err := ioutil.ReadFile(cfg.TrustedNodes)
+		if err != nil {
+			glog.V(logger.Error).Infof("Failed to access trusted nodes: %v", err)
+			return nil
+		}
+		// Interpret the json contents
+		list := []string{}
+		if err := json.Unmarshal(blob, &list); err != nil {
+			glog.V(logger.Error).Infof("Failed to load trusted nodes: %v", err)
+			return nil
+		}
+		// Swap out the configuration for the actual nodes
+		cfg.TrustedNodes = strings.Join(list, " ")
+	}
+	// Interpret the list as a discovery node array
+	var nodes []*discover.Node
+	for _, url := range strings.Split(cfg.TrustedNodes, " ") {
+		if url == "" {
+			continue
+		}
+		node, err := discover.ParseNode(url)
+		if err != nil {
+			glog.V(logger.Error).Infof("Trusted node URL %s: %v\n", url, err)
+			continue
+		}
+		nodes = append(nodes, node)
+	}
+	return nodes
+}
+
 func (cfg *Config) nodeKey() (*ecdsa.PrivateKey, error) {
 	// use explicit key from command line args if set
 	if cfg.NodeKey != nil {
@@ -247,6 +293,7 @@ func New(config *Config) (*Ethereum, error) {
 		NAT:            config.NAT,
 		NoDial:         !config.Dial,
 		BootstrapNodes: config.parseBootNodes(),
+		TrustedNodes:   config.parseTrustedNodes(),
 		NodeDatabase:   nodeDb,
 	}
 	if len(config.Port) > 0 {
@@ -442,12 +489,13 @@ func (s *Ethereum) StartForTest() {
 	s.txPool.Start()
 }
 
-func (self *Ethereum) SuggestPeer(nodeURL string) error {
+// TrustPeer injects a new node into the list of privileged nodes.
+func (self *Ethereum) TrustPeer(nodeURL string) error {
 	n, err := discover.ParseNode(nodeURL)
 	if err != nil {
 		return fmt.Errorf("invalid node URL: %v", err)
 	}
-	self.net.SuggestPeer(n)
+	self.net.TrustPeer(n)
 	return nil
 }
 
diff --git a/p2p/server.go b/p2p/server.go
index 5c5883ae8..794c36125 100644
--- a/p2p/server.go
+++ b/p2p/server.go
@@ -18,8 +18,9 @@ import (
 )
 
 const (
-	defaultDialTimeout   = 10 * time.Second
-	refreshPeersInterval = 30 * time.Second
+	defaultDialTimeout       = 10 * time.Second
+	refreshPeersInterval     = 30 * time.Second
+	trustedPeerCheckInterval = 15 * time.Second
 
 	// This is the maximum number of inbound connection
 	// that are allowed to linger between 'accepted' and
@@ -59,6 +60,10 @@ type Server struct {
 	// with the rest of the network.
 	BootstrapNodes []*discover.Node
 
+	// Trusted nodes are used as privileged connections which are always accepted
+	// and also always maintained.
+	TrustedNodes []*discover.Node
+
 	// NodeDatabase is the path to the database containing the previously seen
 	// live nodes in the network.
 	NodeDatabase string
@@ -99,13 +104,15 @@ type Server struct {
 	running bool
 	peers   map[discover.NodeID]*Peer
 
+	trusts    map[discover.NodeID]*discover.Node // Map of currently trusted remote nodes
+	trustDial chan *discover.Node                // Dial request channel reserved for the trusted nodes
+
 	ntab     *discover.Table
 	listener net.Listener
 
-	quit        chan struct{}
-	loopWG      sync.WaitGroup // {dial,listen,nat}Loop
-	peerWG      sync.WaitGroup // active peer goroutines
-	peerConnect chan *discover.Node
+	quit   chan struct{}
+	loopWG sync.WaitGroup // {dial,listen,nat}Loop
+	peerWG sync.WaitGroup // active peer goroutines
 }
 
 type setupFunc func(net.Conn, *ecdsa.PrivateKey, *protoHandshake, *discover.Node, bool) (*conn, error)
@@ -131,10 +138,9 @@ func (srv *Server) PeerCount() int {
 	return n
 }
 
-// SuggestPeer creates a connection to the given Node if it
-// is not already connected.
-func (srv *Server) SuggestPeer(n *discover.Node) {
-	srv.peerConnect <- n
+// TrustPeer inserts a node into the list of privileged nodes.
+func (srv *Server) TrustPeer(node *discover.Node) {
+	srv.trustDial <- node
 }
 
 // Broadcast sends an RLP-encoded message to all connected peers.
@@ -195,7 +201,14 @@ func (srv *Server) Start() (err error) {
 	}
 	srv.quit = make(chan struct{})
 	srv.peers = make(map[discover.NodeID]*Peer)
-	srv.peerConnect = make(chan *discover.Node)
+
+	// Create the current trust map, and the associated dialing channel
+	srv.trusts = make(map[discover.NodeID]*discover.Node)
+	for _, node := range srv.TrustedNodes {
+		srv.trusts[node.ID] = node
+	}
+	srv.trustDial = make(chan *discover.Node)
+
 	if srv.setupFunc == nil {
 		srv.setupFunc = setupConn
 	}
@@ -229,6 +242,8 @@ func (srv *Server) Start() (err error) {
 	if srv.NoDial && srv.ListenAddr == "" {
 		glog.V(logger.Warn).Infoln("I will be kind-of useless, neither dialing nor listening.")
 	}
+	// maintain the trusted peers
+	go srv.trustLoop()
 
 	srv.running = true
 	return nil
@@ -323,6 +338,45 @@ func (srv *Server) listenLoop() {
 	}
 }
 
+// trustLoop is responsible for periodically checking that trusted connections
+// are actually live, and requests dialing if not.
+func (srv *Server) trustLoop() {
+	// Create a ticker for verifying trusted connections
+	tick := time.Tick(trustedPeerCheckInterval)
+
+	for {
+		select {
+		case <-srv.quit:
+			// Termination requested, simple return
+			return
+
+		case <-tick:
+			// Collect all the non-connected trusted nodes
+			needed := []*discover.Node{}
+			srv.lock.RLock()
+			for id, node := range srv.trusts {
+				if _, ok := srv.peers[id]; !ok {
+					needed = append(needed, node)
+				}
+			}
+			srv.lock.RUnlock()
+
+			// Try to dial each of them (don't hang if server terminates)
+			for _, node := range needed {
+				glog.V(logger.Error).Infof("Dialing trusted peer %v", node)
+				select {
+				case srv.trustDial <- node:
+					// Ok, dialing
+
+				case <-srv.quit:
+					// Terminating, return
+					return
+				}
+			}
+		}
+	}
+}
+
 func (srv *Server) dialLoop() {
 	var (
 		dialed      = make(chan *discover.Node)
@@ -373,7 +427,7 @@ func (srv *Server) dialLoop() {
 				// below MaxPeers.
 				refresh.Reset(refreshPeersInterval)
 			}
-		case dest := <-srv.peerConnect:
+		case dest := <-srv.trustDial:
 			dial(dest)
 		case dests := <-findresults:
 			for _, dest := range dests {
@@ -472,16 +526,26 @@ func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) {
 	return true, 0
 }
 
+// checkPeer verifies whether a peer looks promising and should be allowed/kept
+// in the pool, or if it's of no use.
 func (srv *Server) checkPeer(id discover.NodeID) (bool, DiscReason) {
+	// First up, figure out if the peer is trusted
+	_, trusted := srv.trusts[id]
+
+	// Make sure the peer passes all required checks
 	switch {
 	case !srv.running:
 		return false, DiscQuitting
-	case len(srv.peers) >= srv.MaxPeers:
+
+	case !trusted && len(srv.peers) >= srv.MaxPeers:
 		return false, DiscTooManyPeers
+
 	case srv.peers[id] != nil:
 		return false, DiscAlreadyConnected
+
 	case id == srv.ntab.Self().ID:
 		return false, DiscSelf
+
 	default:
 		return true, 0
 	}
diff --git a/p2p/server_test.go b/p2p/server_test.go
index 53cc3c258..e99d37ed0 100644
--- a/p2p/server_test.go
+++ b/p2p/server_test.go
@@ -102,7 +102,7 @@ func TestServerDial(t *testing.T) {
 
 	// tell the server to connect
 	tcpAddr := listener.Addr().(*net.TCPAddr)
-	srv.SuggestPeer(&discover.Node{IP: tcpAddr.IP, TCPPort: tcpAddr.Port})
+	srv.trustDial <-&discover.Node{IP: tcpAddr.IP, TCPPort: tcpAddr.Port}
 
 	select {
 	case conn := <-accepted: