cmd, eth: support switching client modes of operation

1 files changed, 22 insertions, 18 deletions

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) {