cmd, eth: support switching client modes of operation

8 files changed, 122 insertions, 35 deletions

diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index 3422d9500..ca86fb26f 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -304,6 +304,7 @@ JavaScript API. See https://github.com/ethereum/go-ethereum/wiki/Javascipt-Conso
 		utils.DataDirFlag,
 		utils.BlockchainVersionFlag,
 		utils.OlympicFlag,
+		utils.EthModeFlag,
 		utils.EthVersionFlag,
 		utils.CacheFlag,
 		utils.JSpathFlag,
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index ca9dd76fd..792fcb41d 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -28,6 +28,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 
 	"github.com/codegangsta/cli"
 	"github.com/ethereum/ethash"
@@ -148,9 +149,14 @@ var (
 		Name:  "olympic",
 		Usage: "Use olympic style protocol",
 	}
+	EthModeFlag = cli.StringFlag{
+		Name:  "mode",
+		Value: "archive",
+		Usage: "Client mode of operation (archive, full, light)",
+	}
 	EthVersionFlag = cli.IntFlag{
 		Name:  "eth",
-		Value: 62,
+		Value: 63,
 		Usage: "Highest eth protocol to advertise (temporary, dev option)",
 	}
 
@@ -425,12 +431,25 @@ func MakeEthConfig(clientID, version string, ctx *cli.Context) *eth.Config {
 	if err != nil {
 		glog.V(logger.Error).Infoln("WARNING: No etherbase set and no accounts found as default")
 	}
-
+	// Resolve the mode of opeation from the string flag
+	var clientMode eth.Mode
+	switch strings.ToLower(ctx.GlobalString(EthModeFlag.Name)) {
+	case "archive":
+		clientMode = eth.ArchiveMode
+	case "full":
+		clientMode = eth.FullMode
+	case "light":
+		clientMode = eth.LightMode
+	default:
+		glog.Fatalf("Unknown node type requested: %s", ctx.GlobalString(EthModeFlag.Name))
+	}
+	// Assemble the entire eth configuration and return
 	cfg := &eth.Config{
 		Name:                    common.MakeName(clientID, version),
 		DataDir:                 MustDataDir(ctx),
 		GenesisNonce:            ctx.GlobalInt(GenesisNonceFlag.Name),
 		GenesisFile:             ctx.GlobalString(GenesisFileFlag.Name),
+		Mode:                    clientMode,
 		BlockChainVersion:       ctx.GlobalInt(BlockchainVersionFlag.Name),
 		DatabaseCache:           ctx.GlobalInt(CacheFlag.Name),
 		SkipBcVersionCheck:      false,
@@ -499,7 +518,6 @@ func MakeEthConfig(clientID, version string, ctx *cli.Context) *eth.Config {
 
 		glog.V(logger.Info).Infoln("dev mode enabled")
 	}
-
 	return cfg
 }
 
diff --git a/eth/backend.go b/eth/backend.go
index 9ec3c1440..04dd3767a 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -89,6 +89,7 @@ type Config struct {
 	GenesisFile  string
 	GenesisBlock *types.Block // used by block tests
 	Olympic      bool
+	Mode         Mode
 
 	BlockChainVersion  int
 	SkipBcVersionCheck bool // e.g. blockchain export
@@ -398,8 +399,9 @@ func New(config *Config) (*Ethereum, error) {
 
 	eth.blockProcessor = core.NewBlockProcessor(chainDb, eth.pow, eth.blockchain, eth.EventMux())
 	eth.blockchain.SetProcessor(eth.blockProcessor)
-	eth.protocolManager = NewProtocolManager(config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb)
-
+	if eth.protocolManager, err = NewProtocolManager(config.Mode, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
+		return nil, err
+	}
 	eth.miner = miner.New(eth, eth.EventMux(), eth.pow)
 	eth.miner.SetGasPrice(config.GasPrice)
 	eth.miner.SetExtra(config.ExtraData)
diff --git a/eth/handler.go b/eth/handler.go
index 3fc909672..5716350af 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"errors"
 	"fmt"
 	"math"
 	"math/big"
@@ -42,6 +43,10 @@ const (
 	estHeaderRlpSize  = 500             // Approximate size of an RLP encoded block header
 )
 
+// errIncompatibleConfig is returned if the requested protocols and configs are
+// not compatible (low protocol version restrictions and high requirements).
+var errIncompatibleConfig = errors.New("incompatible configuration")
+
 func errResp(code errCode, format string, v ...interface{}) error {
 	return fmt.Errorf("%v - %v", code, fmt.Sprintf(format, v...))
 }
@@ -49,17 +54,8 @@ func errResp(code errCode, format string, v ...interface{}) error {
 type hashFetcherFn func(common.Hash) error
 type blockFetcherFn func([]common.Hash) error
 
-// extProt is an interface which is passed around so we can expose GetHashes and GetBlock without exposing it to the rest of the protocol
-// extProt is passed around to peers which require to GetHashes and GetBlocks
-type extProt struct {
-	getHashes hashFetcherFn
-	getBlocks blockFetcherFn
-}
-
-func (ep extProt) GetHashes(hash common.Hash) error    { return ep.getHashes(hash) }
-func (ep extProt) GetBlock(hashes []common.Hash) error { return ep.getBlocks(hashes) }
-
 type ProtocolManager struct {
+	mode       Mode
 	txpool     txPool
 	blockchain *core.BlockChain
 	chaindb    ethdb.Database
@@ -87,9 +83,10 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) *ProtocolManager {
+func NewProtocolManager(mode Mode, networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
+		mode:       mode,
 		eventMux:   mux,
 		txpool:     txpool,
 		blockchain: blockchain,
@@ -100,11 +97,15 @@ func NewProtocolManager(networkId int, mux *event.TypeMux, txpool txPool, pow po
 		quitSync:   make(chan struct{}),
 	}
 	// Initiate a sub-protocol for every implemented version we can handle
-	manager.SubProtocols = make([]p2p.Protocol, len(ProtocolVersions))
-	for i := 0; i < len(manager.SubProtocols); i++ {
-		version := ProtocolVersions[i]
-
-		manager.SubProtocols[i] = p2p.Protocol{
+	manager.SubProtocols = make([]p2p.Protocol, 0, len(ProtocolVersions))
+	for i, version := range ProtocolVersions {
+		// Skip protocol version if incompatible with the mode of operation
+		if minimumProtocolVersion[mode] > version {
+			continue
+		}
+		// Compatible, initialize the sub-protocol
+		version := version // Closure for the run
+		manager.SubProtocols = append(manager.SubProtocols, p2p.Protocol{
 			Name:    "eth",
 			Version: version,
 			Length:  ProtocolLengths[i],
@@ -113,7 +114,10 @@ func NewProtocolManager(networkId int, mux *event.TypeMux, txpool txPool, pow po
 				manager.newPeerCh <- peer
 				return manager.handle(peer)
 			},
-		}
+		})
+	}
+	if len(manager.SubProtocols) == 0 {
+		return nil, errIncompatibleConfig
 	}
 	// Construct the different synchronisation mechanisms
 	manager.downloader = downloader.New(manager.eventMux, manager.blockchain.HasBlock, manager.blockchain.GetBlock, manager.blockchain.CurrentBlock, manager.blockchain.GetTd, manager.blockchain.InsertChain, manager.removePeer)
@@ -126,7 +130,7 @@ func NewProtocolManager(networkId int, mux *event.TypeMux, txpool txPool, pow po
 	}
 	manager.fetcher = fetcher.New(manager.blockchain.GetBlock, validator, manager.BroadcastBlock, heighter, manager.blockchain.InsertChain, manager.removePeer)
 
-	return manager
+	return manager, nil
 }
 
 func (pm *ProtocolManager) removePeer(id string) {
diff --git a/eth/handler_test.go b/eth/handler_test.go
index dde2ecbd5..8ab5c1aad 100644
--- a/eth/handler_test.go
+++ b/eth/handler_test.go
@@ -17,12 +17,42 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+// Tests that protocol versions and modes of operations are matched up properly.
+func TestProtocolCompatibility(t *testing.T) {
+	// Define the compatibility chart
+	tests := []struct {
+		version    uint
+		mode       Mode
+		compatible bool
+	}{
+		{61, ArchiveMode, true}, {62, ArchiveMode, true}, {63, ArchiveMode, true}, {64, ArchiveMode, true},
+		{61, FullMode, false}, {62, FullMode, false}, {63, FullMode, true}, {64, FullMode, true},
+		{61, LightMode, false}, {62, LightMode, false}, {63, LightMode, false}, {64, LightMode, true},
+	}
+	// Make sure anything we screw up is restored
+	backup := ProtocolVersions
+	defer func() { ProtocolVersions = backup }()
+
+	// Try all available compatibility configs and check for errors
+	for i, tt := range tests {
+		ProtocolVersions = []uint{tt.version}
+
+		pm, err := newTestProtocolManager(tt.mode, 0, nil, nil)
+		if pm != nil {
+			defer pm.Stop()
+		}
+		if (err == nil && !tt.compatible) || (err != nil && tt.compatible) {
+			t.Errorf("test %d: compatibility mismatch: have error %v, want compatibility %v", i, err, tt.compatible)
+		}
+	}
+}
+
 // Tests that hashes can be retrieved from a remote chain by hashes in reverse
 // order.
 func TestGetBlockHashes61(t *testing.T) { testGetBlockHashes(t, 61) }
 
 func testGetBlockHashes(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(downloader.MaxHashFetch+15, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, downloader.MaxHashFetch+15, nil, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -65,7 +95,7 @@ func testGetBlockHashes(t *testing.T, protocol int) {
 func TestGetBlockHashesFromNumber61(t *testing.T) { testGetBlockHashesFromNumber(t, 61) }
 
 func testGetBlockHashesFromNumber(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(downloader.MaxHashFetch+15, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, downloader.MaxHashFetch+15, nil, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -105,7 +135,7 @@ func testGetBlockHashesFromNumber(t *testing.T, protocol int) {
 func TestGetBlocks61(t *testing.T) { testGetBlocks(t, 61) }
 
 func testGetBlocks(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(downloader.MaxHashFetch+15, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, downloader.MaxHashFetch+15, nil, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -177,7 +207,7 @@ func TestGetBlockHeaders63(t *testing.T) { testGetBlockHeaders(t, 63) }
 func TestGetBlockHeaders64(t *testing.T) { testGetBlockHeaders(t, 64) }
 
 func testGetBlockHeaders(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(downloader.MaxHashFetch+15, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, downloader.MaxHashFetch+15, nil, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -303,7 +333,7 @@ func TestGetBlockBodies63(t *testing.T) { testGetBlockBodies(t, 63) }
 func TestGetBlockBodies64(t *testing.T) { testGetBlockBodies(t, 64) }
 
 func testGetBlockBodies(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(downloader.MaxBlockFetch+15, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, downloader.MaxBlockFetch+15, nil, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -410,7 +440,7 @@ func testGetNodeData(t *testing.T, protocol int) {
 		}
 	}
 	// Assemble the test environment
-	pm := newTestProtocolManager(4, generator, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, 4, generator, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
@@ -500,7 +530,7 @@ func testGetReceipt(t *testing.T, protocol int) {
 		}
 	}
 	// Assemble the test environment
-	pm := newTestProtocolManager(4, generator, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, 4, generator, nil)
 	peer, _ := newTestPeer("peer", protocol, pm, true)
 	defer peer.close()
 
diff --git a/eth/helper_test.go b/eth/helper_test.go
index 9314884ef..bd65b49f8 100644
--- a/eth/helper_test.go
+++ b/eth/helper_test.go
@@ -28,7 +28,7 @@ var (
 // newTestProtocolManager creates a new protocol manager for testing purposes,
 // with the given number of blocks already known, and potential notification
 // channels for different events.
-func newTestProtocolManager(blocks int, generator func(int, *core.BlockGen), newtx chan<- []*types.Transaction) *ProtocolManager {
+func newTestProtocolManager(mode Mode, blocks int, generator func(int, *core.BlockGen), newtx chan<- []*types.Transaction) (*ProtocolManager, error) {
 	var (
 		evmux         = new(event.TypeMux)
 		pow           = new(core.FakePow)
@@ -42,8 +42,23 @@ func newTestProtocolManager(blocks int, generator func(int, *core.BlockGen), new
 	if _, err := blockchain.InsertChain(chain); err != nil {
 		panic(err)
 	}
-	pm := NewProtocolManager(NetworkId, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
+	pm, err := NewProtocolManager(mode, NetworkId, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
+	if err != nil {
+		return nil, err
+	}
 	pm.Start()
+	return pm, nil
+}
+
+// newTestProtocolManagerMust creates a new protocol manager for testing purposes,
+// with the given number of blocks already known, and potential notification
+// channels for different events. In case of an error, the constructor force-
+// fails the test.
+func newTestProtocolManagerMust(t *testing.T, mode Mode, blocks int, generator func(int, *core.BlockGen), newtx chan<- []*types.Transaction) *ProtocolManager {
+	pm, err := newTestProtocolManager(mode, blocks, generator, newtx)
+	if err != nil {
+		t.Fatalf("Failed to create protocol manager: %v", err)
+	}
 	return pm
 }
 
diff --git a/eth/protocol.go b/eth/protocol.go
index 49f096a3b..0d2b5128d 100644
--- a/eth/protocol.go
+++ b/eth/protocol.go
@@ -26,6 +26,15 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
+// Mode represents the mode of operation of the eth client.
+type Mode int
+
+const (
+	ArchiveMode Mode = iota // Maintain the entire blockchain history
+	FullMode                // Maintain only a recent view of the blockchain
+	LightMode               // Don't maintain any history, rather fetch on demand
+)
+
 // Constants to match up protocol versions and messages
 const (
 	eth61 = 61
@@ -34,6 +43,14 @@ const (
 	eth64 = 64
 )
 
+// minimumProtocolVersion is the minimum version of the protocol eth must run to
+// support the desired mode of operation.
+var minimumProtocolVersion = map[Mode]uint{
+	ArchiveMode: eth61,
+	FullMode:    eth63,
+	LightMode:   eth64,
+}
+
 // Supported versions of the eth protocol (first is primary).
 var ProtocolVersions = []uint{eth64, eth63, eth62, eth61}
 
diff --git a/eth/protocol_test.go b/eth/protocol_test.go
index 523e6c1eb..bac519ae3 100644
--- a/eth/protocol_test.go
+++ b/eth/protocol_test.go
@@ -44,7 +44,7 @@ func TestStatusMsgErrors63(t *testing.T) { testStatusMsgErrors(t, 63) }
 func TestStatusMsgErrors64(t *testing.T) { testStatusMsgErrors(t, 64) }
 
 func testStatusMsgErrors(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(0, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, 0, nil, nil)
 	td, currentBlock, genesis := pm.blockchain.Status()
 	defer pm.Stop()
 
@@ -99,7 +99,7 @@ func TestRecvTransactions64(t *testing.T) { testRecvTransactions(t, 64) }
 
 func testRecvTransactions(t *testing.T, protocol int) {
 	txAdded := make(chan []*types.Transaction)
-	pm := newTestProtocolManager(0, nil, txAdded)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, 0, nil, txAdded)
 	p, _ := newTestPeer("peer", protocol, pm, true)
 	defer pm.Stop()
 	defer p.close()
@@ -127,7 +127,7 @@ func TestSendTransactions63(t *testing.T) { testSendTransactions(t, 63) }
 func TestSendTransactions64(t *testing.T) { testSendTransactions(t, 64) }
 
 func testSendTransactions(t *testing.T, protocol int) {
-	pm := newTestProtocolManager(0, nil, nil)
+	pm := newTestProtocolManagerMust(t, ArchiveMode, 0, nil, nil)
 	defer pm.Stop()
 
 	// Fill the pool with big transactions.