Implement a GetCFilterHeader RPC command

btcjson/chainsvrcmds.go

@@ -293,6 +293,21 @@ func NewGetCFilterCmd(hash string, extended bool) *GetCFilterCmd {
 	}
 }
 
+// GetCFilterHeaderCmd defines the getcfilterheader JSON-RPC command.
+type GetCFilterHeaderCmd struct {
+	Hash     string
+	Extended bool
+}
+
+// NewGetCFilterHeaderCmd returns a new instance which can be used to issue a
+// getcfilterheader JSON-RPC command.
+func NewGetCFilterHeaderCmd(hash string, extended bool) *GetCFilterHeaderCmd {
+	return &GetCFilterHeaderCmd{
+		Hash:     hash,
+		Extended: extended,
+	}
+}
+
 // GetChainTipsCmd defines the getchaintips JSON-RPC command.
 type GetChainTipsCmd struct{}
 
@@ -771,6 +786,7 @@ func init() {
 	MustRegisterCmd("getblockheader", (*GetBlockHeaderCmd)(nil), flags)
 	MustRegisterCmd("getblocktemplate", (*GetBlockTemplateCmd)(nil), flags)
 	MustRegisterCmd("getcfilter", (*GetCFilterCmd)(nil), flags)
+	MustRegisterCmd("getcfilterheader", (*GetCFilterHeaderCmd)(nil), flags)
 	MustRegisterCmd("getchaintips", (*GetChainTipsCmd)(nil), flags)
 	MustRegisterCmd("getconnectioncount", (*GetConnectionCountCmd)(nil), flags)
 	MustRegisterCmd("getdifficulty", (*GetDifficultyCmd)(nil), flags)

btcjson/chainsvrcmds_test.go

@@ -330,6 +330,19 @@ func TestChainSvrCmds(t *testing.T) {
 				Hash:    "123",
 			},
 		},
+		{
+			name: "getcfilterheader",
+			newCmd: func() (interface{}, error) {
+				return btcjson.NewCmd("getcfilterheader", "123", false)
+			},
+			staticCmd: func() interface{} {
+				return btcjson.NewGetCFilterHeaderCmd("123", false)
+			},
+			marshalled: `{"jsonrpc":"1.0","method":"getcfilterheader","params":["123",false],"id":1}`,
+			unmarshalled: &btcjson.GetCFilterHeaderCmd{
+				Hash:    "123",
+			},
+		},
 		{
 			name: "getchaintips",
 			newCmd: func() (interface{}, error) {

rpcserver.go

@@ -143,6 +143,7 @@ var rpcHandlersBeforeInit = map[string]commandHandler{
 	"getblockheader":        handleGetBlockHeader,
 	"getblocktemplate":      handleGetBlockTemplate,
 	"getcfilter":            handleGetCFilter,
+	"getcfilterheader":      handleGetCFilterHeader,
 	"getconnectioncount":    handleGetConnectionCount,
 	"getcurrentnet":         handleGetCurrentNet,
 	"getdifficulty":         handleGetDifficulty,
@@ -260,6 +261,7 @@ var rpcLimited = map[string]struct{}{
 	"getblockhash":          {},
 	"getblockheader":        {},
 	"getcfilter":            {},
+	"getcfilterheader":      {},
 	"getcurrentnet":         {},
 	"getdifficulty":         {},
 	"getheaders":            {},
@@ -2169,6 +2171,29 @@ func handleGetCFilter(s *rpcServer, cmd interface{}, closeChan <-chan struct{})
 	return hex.EncodeToString(filterBytes), nil
 }
 
+// handleGetCFilterHeader implements the getcfilterheader command.
+func handleGetCFilterHeader(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
+	c := cmd.(*btcjson.GetCFilterHeaderCmd)
+	hash, err := chainhash.NewHashFromStr(c.Hash)
+	if err != nil {
+		return nil, rpcDecodeHexError(c.Hash)
+	}
+
+	headerBytes, err := s.server.cfIndex.FilterHeaderByBlockHash(hash, c.Extended)
+	if len(headerBytes) > 0 {
+		rpcsLog.Debugf("Found header of committed filter for %v", hash)
+	} else {
+		rpcsLog.Debugf("Could not find header of committed filter for %v: %v",
+		    hash, err)
+		return nil, &btcjson.RPCError{
+			Code:    btcjson.ErrRPCBlockNotFound,
+			Message: "Block not found",
+		}
+	}
+
+	return hex.EncodeToString(headerBytes), nil
+}
+
 // handleGetConnectionCount implements the getconnectioncount command.
 func handleGetConnectionCount(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
 	return s.cfg.ConnMgr.ConnectedCount(), nil