node: customizable protocol and service stacks

node/config.go

@@ -0,0 +1,171 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package node
+
+import (
+	"crypto/ecdsa"
+	"encoding/json"
+	"io/ioutil"
+	"net"
+	"os"
+	"path/filepath"
+
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+	"github.com/ethereum/go-ethereum/p2p/nat"
+)
+
+var (
+	datadirPrivateKey   = "nodekey"            // Path within the datadir to the node's private key
+	datadirStaticNodes  = "static-nodes.json"  // Path within the datadir to the static node list
+	datadirTrustedNodes = "trusted-nodes.json" // Path within the datadir to the trusted node list
+	datadirNodeDatabase = "nodes"              // Path within the datadir to store the node infos
+)
+
+// Config represents a small collection of configuration values to fine tune the
+// P2P network layer of a protocol stack. These values can be further extended by
+// all registered services.
+type Config struct {
+	// DataDir is the file system folder the node should use for any data storage
+	// requirements. The configured data directory will not be directly shared with
+	// registered services, instead those can use utility methods to create/access
+	// databases or flat files. This enables ephemeral nodes which can fully reside
+	// in memory.
+	DataDir string
+
+	// This field should be a valid secp256k1 private key that will be used for both
+	// remote peer identification as well as network traffic encryption. If no key
+	// is configured, the preset one is loaded from the data dir, generating it if
+	// needed.
+	PrivateKey *ecdsa.PrivateKey
+
+	// Name sets the node name of this server. Use common.MakeName to create a name
+	// that follows existing conventions.
+	Name string
+
+	// NoDiscovery specifies whether the peer discovery mechanism should be started
+	// or not. Disabling is usually useful for protocol debugging (manual topology).
+	NoDiscovery bool
+
+	// Bootstrap nodes used to establish connectivity with the rest of the network.
+	BootstrapNodes []*discover.Node
+
+	// Network interface address on which the node should listen for inbound peers.
+	ListenAddr string
+
+	// If set to a non-nil value, the given NAT port mapper is used to make the
+	// listening port available to the Internet.
+	NAT nat.Interface
+
+	// If Dialer is set to a non-nil value, the given Dialer is used to dial outbound
+	// peer connections.
+	Dialer *net.Dialer
+
+	// If NoDial is true, the node will not dial any peers.
+	NoDial bool
+
+	// MaxPeers is the maximum number of peers that can be connected. If this is
+	// set to zero, then only the configured static and trusted peers can connect.
+	MaxPeers int
+
+	// MaxPendingPeers is the maximum number of peers that can be pending in the
+	// handshake phase, counted separately for inbound and outbound connections.
+	// Zero defaults to preset values.
+	MaxPendingPeers int
+}
+
+// NodeKey retrieves the currently configured private key of the node, checking
+// first any manually set key, falling back to the one found in the configured
+// data folder. If no key can be found, a new one is generated.
+func (c *Config) NodeKey() *ecdsa.PrivateKey {
+	// Use any specifically configured key
+	if c.PrivateKey != nil {
+		return c.PrivateKey
+	}
+	// Generate ephemeral key if no datadir is being used
+	if c.DataDir == "" {
+		key, err := crypto.GenerateKey()
+		if err != nil {
+			glog.Fatalf("Failed to generate ephemeral node key: %v", err)
+		}
+		return key
+	}
+	// Fall back to persistent key from the data directory
+	keyfile := filepath.Join(c.DataDir, datadirPrivateKey)
+	if key, err := crypto.LoadECDSA(keyfile); err == nil {
+		return key
+	}
+	// No persistent key found, generate and store a new one
+	key, err := crypto.GenerateKey()
+	if err != nil {
+		glog.Fatalf("Failed to generate node key: %v", err)
+	}
+	if err := crypto.SaveECDSA(keyfile, key); err != nil {
+		glog.V(logger.Error).Infof("Failed to persist node key: %v", err)
+	}
+	return key
+}
+
+// StaticNodes returns a list of node enode URLs configured as static nodes.
+func (c *Config) StaticNodes() []*discover.Node {
+	return c.parsePersistentNodes(datadirStaticNodes)
+}
+
+// TrusterNodes returns a list of node enode URLs configured as trusted nodes.
+func (c *Config) TrusterNodes() []*discover.Node {
+	return c.parsePersistentNodes(datadirTrustedNodes)
+}
+
+// parsePersistentNodes parses a list of discovery node URLs loaded from a .json
+// file from within the data directory.
+func (c *Config) parsePersistentNodes(file string) []*discover.Node {
+	// Short circuit if no node config is present
+	if c.DataDir == "" {
+		return nil
+	}
+	path := filepath.Join(c.DataDir, file)
+	if _, err := os.Stat(path); err != nil {
+		return nil
+	}
+	// Load the nodes from the config file
+	blob, err := ioutil.ReadFile(path)
+	if err != nil {
+		glog.V(logger.Error).Infof("Failed to access nodes: %v", err)
+		return nil
+	}
+	nodelist := []string{}
+	if err := json.Unmarshal(blob, &nodelist); err != nil {
+		glog.V(logger.Error).Infof("Failed to load nodes: %v", err)
+		return nil
+	}
+	// Interpret the list as a discovery node array
+	var nodes []*discover.Node
+	for _, url := range nodelist {
+		if url == "" {
+			continue
+		}
+		node, err := discover.ParseNode(url)
+		if err != nil {
+			glog.V(logger.Error).Infof("Node URL %s: %v\n", url, err)
+			continue
+		}
+		nodes = append(nodes, node)
+	}
+	return nodes
+}