First crack it providing fast-sync endpoint

blockchain/reactor.go

@@ -267,6 +267,11 @@ func (bcR *BlockchainReactor) SetEventSwitch(evsw types.EventSwitch) {
 	bcR.evsw = evsw
 }
 
+// FastSync returns whether the blockchain reactor is currently fast syncing
+func (bcR *BlockchainReactor) FastSync() bool {
+	return bcR.fastSync
+}
+
 //-----------------------------------------------------------------------------
 // Messages
 

node/node.go

@@ -315,6 +315,7 @@ func (n *Node) ConfigureRPC() {
 	rpccore.SetAddrBook(n.addrBook)
 	rpccore.SetProxyAppQuery(n.proxyApp.Query())
 	rpccore.SetTxIndexer(n.txIndexer)
+	rpccore.SetBlockchainReactor(n.bcReactor)
 	rpccore.SetLogger(n.Logger.With("module", "rpc"))
 }
 

rpc/core/pipe.go

@@ -2,6 +2,7 @@ package core
 
 import (
 	crypto "github.com/tendermint/go-crypto"
+	"github.com/tendermint/tendermint/blockchain"
 	"github.com/tendermint/tendermint/consensus"
 	p2p "github.com/tendermint/tendermint/p2p"
 	"github.com/tendermint/tendermint/proxy"
@@ -45,6 +46,7 @@ var (
 	genDoc    *types.GenesisDoc // cache the genesis structure
 	addrBook  *p2p.AddrBook
 	txIndexer txindex.TxIndexer
+	bcReactor *blockchain.BlockchainReactor
 
 	logger log.Logger
 )
@@ -89,6 +91,10 @@ func SetTxIndexer(indexer txindex.TxIndexer) {
 	txIndexer = indexer
 }
 
+func SetBlockchainReactor(bc *blockchain.BlockchainReactor) {
+	bcReactor = bc
+}
+
 func SetLogger(l log.Logger) {
 	logger = l
 }

rpc/core/status.go

@@ -27,5 +27,6 @@ func Status() (*ctypes.ResultStatus, error) {
 		LatestBlockHash:   latestBlockHash,
 		LatestAppHash:     latestAppHash,
 		LatestBlockHeight: latestHeight,
-		LatestBlockTime:   latestBlockTime}, nil
+		LatestBlockTime:   latestBlockTime,
+		Syncing:           bcReactor.FastSync()}, nil
 }

rpc/core/types/responses.go

@@ -38,6 +38,7 @@ type ResultStatus struct {
 	LatestAppHash     data.Bytes    `json:"latest_app_hash"`
 	LatestBlockHeight int           `json:"latest_block_height"`
 	LatestBlockTime   int64         `json:"latest_block_time"` // nano
+	Syncing           bool          `json:"syncing"`
 }
 
 func (s *ResultStatus) TxIndexEnabled() bool {