feat: add bootnode binary (#397)

bootnode/bootnode.go

@@ -0,0 +1,86 @@
+// Copyright 2023 The AthanorLabs/atomic-swap Authors
+// SPDX-License-Identifier: LGPL-3.0-only
+
+// Package bootnode is responsible for assembling, running and cleanly shutting
+// down a swap bootnode.
+package bootnode
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math/big"
+	"net/http"
+
+	"github.com/athanorlabs/atomic-swap/net"
+	"github.com/athanorlabs/atomic-swap/rpc"
+
+	"github.com/hashicorp/go-multierror"
+	logging "github.com/ipfs/go-log"
+)
+
+var log = logging.Logger("bootnode")
+
+// Config provides the configuration for a bootnode.
+type Config struct {
+	DataDir         string
+	Bootnodes       []string
+	HostListenIP    string
+	Libp2pPort      uint16
+	Libp2pKeyFile   string
+	RPCPort         uint16
+	EthereumChainID *big.Int
+}
+
+// RunBootnode assembles and runs a bootnode instance, blocking until the node is
+// shut down. Typically, shutdown happens because a signal handler cancels the
+// passed in context, or when the shutdown RPC method is called.
+func RunBootnode(ctx context.Context, cfg *Config) error {
+	host, err := net.NewHost(&net.Config{
+		Ctx:            ctx,
+		DataDir:        cfg.DataDir,
+		Port:           cfg.Libp2pPort,
+		KeyFile:        cfg.Libp2pKeyFile,
+		Bootnodes:      cfg.Bootnodes,
+		ProtocolID:     fmt.Sprintf("%s/%d", net.ProtocolID, cfg.EthereumChainID.Int64()),
+		ListenIP:       cfg.HostListenIP,
+		IsRelayer:      false,
+		IsBootnodeOnly: true,
+	})
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if hostErr := host.Stop(); hostErr != nil {
+			err = multierror.Append(err, fmt.Errorf("error shutting down peer-to-peer services: %w", hostErr))
+		}
+	}()
+
+	if err = host.Start(); err != nil {
+		return err
+	}
+
+	rpcServer, err := rpc.NewServer(&rpc.Config{
+		Ctx:     ctx,
+		Address: fmt.Sprintf("127.0.0.1:%d", cfg.RPCPort),
+		Net:     host,
+		Namespaces: map[string]struct{}{
+			rpc.DaemonNamespace: {},
+			rpc.NetNamespace:    {},
+		},
+		IsBootnodeOnly: true,
+	})
+
+	log.Infof("starting bootnode with data-dir %s", cfg.DataDir)
+	err = rpcServer.Start()
+
+	if errors.Is(err, http.ErrServerClosed) {
+		// Remove the error for a clean program exit, as ErrServerClosed only
+		// happens when the server is told to shut down
+		err = nil
+	}
+
+	// err can get set in defer blocks, so return err or use an empty
+	// return statement below (not nil)
+	return err
+}