From 462aa646d1e1f7d5bf1de904411198dadc826be3 Mon Sep 17 00:00:00 2001
From: jsvisa <delweng@gmail.com>
Date: Mon, 18 Sep 2023 06:56:58 +0000
Subject: [PATCH] cmd/devp2p: return error if no nodes available

Signed-off-by: jsvisa <delweng@gmail.com>
---
 cmd/devp2p/crawl.go     | 12 ++++++++++--
 cmd/devp2p/discv4cmd.go | 13 ++++++-------
 cmd/devp2p/discv5cmd.go |  6 +++---
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/cmd/devp2p/crawl.go b/cmd/devp2p/crawl.go
index 8c0defff6d..4288a5feb8 100644
--- a/cmd/devp2p/crawl.go
+++ b/cmd/devp2p/crawl.go
@@ -17,6 +17,7 @@
 package main
 
 import (
+	"errors"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -51,7 +52,14 @@ type resolver interface {
 	RequestENR(*enode.Node) (*enode.Node, error)
 }
 
-func newCrawler(input nodeSet, disc resolver, iters ...enode.Iterator) *crawler {
+func newCrawler(input nodeSet, bootnodes []*enode.Node, disc resolver, iters ...enode.Iterator) (*crawler, error) {
+	if len(input) == 0 {
+		input.add(bootnodes...)
+	}
+	if len(input) == 0 {
+		return nil, errors.New("no input nodes to start crawling")
+	}
+
 	c := &crawler{
 		input:     input,
 		output:    make(nodeSet, len(input)),
@@ -67,7 +75,7 @@ func newCrawler(input nodeSet, disc resolver, iters ...enode.Iterator) *crawler
 	for id, n := range input {
 		c.output[id] = n
 	}
-	return c
+	return c, nil
 }
 
 func (c *crawler) run(timeout time.Duration, nthreads int) nodeSet {
diff --git a/cmd/devp2p/discv4cmd.go b/cmd/devp2p/discv4cmd.go
index 9848002b86..37b139dea2 100644
--- a/cmd/devp2p/discv4cmd.go
+++ b/cmd/devp2p/discv4cmd.go
@@ -196,14 +196,13 @@ func discv4ResolveJSON(ctx *cli.Context) error {
 		nodeargs = append(nodeargs, n)
 	}
 
-	// Run the crawler.
 	disc, config := startV4(ctx)
 	defer disc.Close()
 
-	if len(inputSet) == 0 {
-		inputSet.add(config.Bootnodes...)
+	c, err := newCrawler(inputSet, config.Bootnodes, disc, enode.IterNodes(nodeargs))
+	if err != nil {
+		return err
 	}
-	c := newCrawler(inputSet, disc, enode.IterNodes(nodeargs))
 	c.revalidateInterval = 0
 	output := c.run(0, 1)
 	writeNodesJSON(nodesFile, output)
@@ -223,10 +222,10 @@ func discv4Crawl(ctx *cli.Context) error {
 	disc, config := startV4(ctx)
 	defer disc.Close()
 
-	if len(inputSet) == 0 {
-		inputSet.add(config.Bootnodes...)
+	c, err := newCrawler(inputSet, config.Bootnodes, disc, disc.RandomNodes())
+	if err != nil {
+		return err
 	}
-	c := newCrawler(inputSet, disc, disc.RandomNodes())
 	c.revalidateInterval = 10 * time.Minute
 	output := c.run(ctx.Duration(crawlTimeoutFlag.Name), ctx.Int(crawlParallelismFlag.Name))
 	writeNodesJSON(nodesFile, output)
diff --git a/cmd/devp2p/discv5cmd.go b/cmd/devp2p/discv5cmd.go
index 8c11bc5d3b..0dac945269 100644
--- a/cmd/devp2p/discv5cmd.go
+++ b/cmd/devp2p/discv5cmd.go
@@ -110,10 +110,10 @@ func discv5Crawl(ctx *cli.Context) error {
 	disc, config := startV5(ctx)
 	defer disc.Close()
 
-	if len(inputSet) == 0 {
-		inputSet.add(config.Bootnodes...)
+	c, err := newCrawler(inputSet, config.Bootnodes, disc, disc.RandomNodes())
+	if err != nil {
+		return err
 	}
-	c := newCrawler(inputSet, disc, disc.RandomNodes())
 	c.revalidateInterval = 10 * time.Minute
 	output := c.run(ctx.Duration(crawlTimeoutFlag.Name), ctx.Int(crawlParallelismFlag.Name))
 	writeNodesJSON(nodesFile, output)