feat: test program to fetch single block

Fixes #212

Author: agaffney

.gitignore

@@ -6,6 +6,7 @@
 *.dylib
 /go-ouroboros-network
 /tx-monitor
+/block-fetch
 
 # Test binary, built with `go test -c`
 *.test

cmd/block-fetch/main.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"encoding/hex"
+	"fmt"
+	"os"
+
+	"github.com/cloudstruct/go-ouroboros-network"
+	"github.com/cloudstruct/go-ouroboros-network/cmd/common"
+	"github.com/cloudstruct/go-ouroboros-network/ledger"
+	ocommon "github.com/cloudstruct/go-ouroboros-network/protocol/common"
+)
+
+type blockFetchFlags struct {
+	*common.GlobalFlags
+	slot uint64
+	hash string
+}
+
+func main() {
+	// Parse commandline
+	f := blockFetchFlags{
+		GlobalFlags: common.NewGlobalFlags(),
+	}
+	f.Flagset.Uint64Var(&f.slot, "slot", 0, "slot for single block to fetch")
+	f.Flagset.StringVar(&f.hash, "hash", "", "hash for single block to fetch")
+	f.Parse()
+	// Create connection
+	conn := common.CreateClientConnection(f.GlobalFlags)
+	errorChan := make(chan error)
+	go func() {
+		for {
+			err := <-errorChan
+			fmt.Printf("ERROR(async): %s\n", err)
+			os.Exit(1)
+		}
+	}()
+	o, err := ouroboros.New(
+		ouroboros.WithConnection(conn),
+		ouroboros.WithNetworkMagic(uint32(f.NetworkMagic)),
+		ouroboros.WithErrorChan(errorChan),
+		ouroboros.WithNodeToNode(f.NtnProto),
+		ouroboros.WithKeepAlive(true),
+	)
+	if err != nil {
+		fmt.Printf("ERROR: %s\n", err)
+		os.Exit(1)
+	}
+	o.BlockFetch().Client.Start()
+
+	blockHash, err := hex.DecodeString(f.hash)
+	if err != nil {
+		fmt.Printf("ERROR: failed to decode block hash: %s\n", err)
+		os.Exit(1)
+	}
+	block, err := o.BlockFetch().Client.GetBlock(ocommon.NewPoint(f.slot, blockHash))
+	if err != nil {
+		fmt.Printf("ERROR: failed to fetch block: %s\n", err)
+		os.Exit(1)
+	}
+
+	// Display block info
+	switch v := block.(type) {
+	case *ledger.ByronEpochBoundaryBlock:
+		fmt.Printf("era = Byron (EBB), epoch = %d, id = %s\n", v.Header.ConsensusData.Epoch, v.Hash())
+	case *ledger.ByronMainBlock:
+		fmt.Printf("era = Byron, epoch = %d, slot = %d, id = %s\n", v.Header.ConsensusData.SlotId.Epoch, v.SlotNumber(), v.Hash())
+	case ledger.Block:
+		fmt.Printf("era = %s, slot = %d, block_no = %d, id = %s\n", v.Era().Name, v.SlotNumber(), v.BlockNumber(), v.Hash())
+	}
+}