feat: blockfetch server support

Fixes #348

Author: agaffney

protocol/blockfetch/blockfetch.go

@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"github.com/blinklabs-io/gouroboros/protocol"
+	"github.com/blinklabs-io/gouroboros/protocol/common"
 
 	"github.com/blinklabs-io/gouroboros/ledger"
 )
@@ -86,12 +87,14 @@ type BlockFetch struct {
 
 type Config struct {
 	BlockFunc         BlockFunc
+	RequestRangeFunc  RequestRangeFunc
 	BatchStartTimeout time.Duration
 	BlockTimeout      time.Duration
 }
 
 // Callback function types
 type BlockFunc func(ledger.Block) error
+type RequestRangeFunc func(common.Point, common.Point) error
 
 func New(protoOptions protocol.ProtocolOptions, cfg *Config) *BlockFetch {
 	b := &BlockFetch{
@@ -121,6 +124,12 @@ func WithBlockFunc(blockFunc BlockFunc) BlockFetchOptionFunc {
 	}
 }
 
+func WithRequestRangeFunc(requestRangeFunc RequestRangeFunc) BlockFetchOptionFunc {
+	return func(c *Config) {
+		c.RequestRangeFunc = requestRangeFunc
+	}
+}
+
 func WithBatchStartTimeout(timeout time.Duration) BlockFetchOptionFunc {
 	return func(c *Config) {
 		c.BatchStartTimeout = timeout

protocol/blockfetch/messages.go

@@ -16,8 +16,10 @@ package blockfetch
 
 import (
 	"fmt"
+
 	"github.com/blinklabs-io/gouroboros/cbor"
 	"github.com/blinklabs-io/gouroboros/protocol"
+	"github.com/blinklabs-io/gouroboros/protocol/common"
 )
 
 const (
@@ -57,11 +59,11 @@ func NewMsgFromCbor(msgType uint, data []byte) (protocol.Message, error) {
 
 type MsgRequestRange struct {
 	protocol.MessageBase
-	Start interface{} //point
-	End   interface{} //point
+	Start common.Point
+	End   common.Point
 }
 
-func NewMsgRequestRange(start interface{}, end interface{}) *MsgRequestRange {
+func NewMsgRequestRange(start common.Point, end common.Point) *MsgRequestRange {
 	m := &MsgRequestRange{
 		MessageBase: protocol.MessageBase{
 			MessageType: MessageTypeRequestRange,
@@ -139,17 +141,8 @@ func NewMsgBatchDone() *MsgBatchDone {
 	return m
 }
 
-// TODO: use this above and expose it, or just remove it
-/*
-type point struct {
-	Slot uint64
-	Hash []byte
-}
-*/
-
 type WrappedBlock struct {
-	// Tells the CBOR decoder to convert to/from a struct and a CBOR array
-	_        struct{} `cbor:",toarray"`
+	cbor.StructAsArray
 	Type     uint
 	RawBlock cbor.RawMessage
 }

protocol/blockfetch/server.go

@@ -16,6 +16,8 @@ package blockfetch
 
 import (
 	"fmt"
+
+	"github.com/blinklabs-io/gouroboros/cbor"
 	"github.com/blinklabs-io/gouroboros/protocol"
 )
 
@@ -44,10 +46,41 @@ func NewServer(protoOptions protocol.ProtocolOptions, cfg *Config) *Server {
 	return s
 }
 
+func (s *Server) NoBlocks() error {
+	msg := NewMsgNoBlocks()
+	return s.SendMessage(msg)
+}
+
+func (s *Server) StartBatch() error {
+	msg := NewMsgStartBatch()
+	return s.SendMessage(msg)
+}
+
+func (s *Server) Block(blockType uint, blockData []byte) error {
+	wrappedBlock := WrappedBlock{
+		Type:     blockType,
+		RawBlock: blockData,
+	}
+	wrappedBlockData, err := cbor.Encode(&wrappedBlock)
+	if err != nil {
+		return err
+	}
+	msg := NewMsgBlock(wrappedBlockData)
+	return s.SendMessage(msg)
+}
+
+func (s *Server) BatchDone() error {
+	msg := NewMsgBatchDone()
+	return s.SendMessage(msg)
+}
+
 func (s *Server) messageHandler(msg protocol.Message) error {
 	var err error
-	// TODO: add cases for messages from client
 	switch msg.Type() {
+	case MessageTypeRequestRange:
+		err = s.handleRequestRange(msg)
+	case MessageTypeClientDone:
+		err = s.handleClientDone()
 	default:
 		err = fmt.Errorf(
 			"%s: received unexpected message type %d",
@@ -57,3 +90,17 @@ func (s *Server) messageHandler(msg protocol.Message) error {
 	}
 	return err
 }
+
+func (s *Server) handleRequestRange(msg protocol.Message) error {
+	if s.config == nil || s.config.RequestRangeFunc == nil {
+		return fmt.Errorf(
+			"received block-fetch RequestRange message but no callback function is defined",
+		)
+	}
+	msgRequestRange := msg.(*MsgRequestRange)
+	return s.config.RequestRangeFunc(msgRequestRange.Start, msgRequestRange.End)
+}
+
+func (s *Server) handleClientDone() error {
+	return nil
+}