Fix wildcard filtering with long domains

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- Wildcard filtering not working when wildcard tests put the domain over the 253 character limit.
+
 ## [2.1.1] - 2023-04-11
 ### Fixed
 - Wrong version number in binary releases

internal/app/version.go

@@ -8,7 +8,7 @@ const (
 	AppDesc string = "Very accurate massdns resolving and bruteforcing."
 
 	// AppVersion is the program version.
-	AppVersion string = "v2.1.1"
+	AppVersion string = "v2.1.2"
 
 	// AppSponsorsURL is the text file containing sponsors information.
 	AppSponsorsURL string = "https://gist.githubusercontent.com/d3mondev/0bfff529a4dad627bdb684ad1ef2506d/raw/sponsors.txt"

pkg/wildcarder/randomsub.go

@@ -5,6 +5,8 @@ import (
 	"time"
 )
 
+const randomSubdomainLength = 16
+
 func newRandomSubdomains(count int) []string {
 	const letters = "abcdefghijklmnopqrstuvwxyz1234567890"
 
@@ -13,7 +15,7 @@ func newRandomSubdomains(count int) []string {
 	var subs []string
 
 	for i := 0; i < count; i++ {
-		b := make([]byte, 16)
+		b := make([]byte, randomSubdomainLength)
 
 		for i := range b {
 			b[i] = letters[rng.Intn(len(letters))]

pkg/wildcarder/wildcarder.go

@@ -90,6 +90,11 @@ func (wc *Wildcarder) Filter(r io.Reader) (domains, roots []string) {
 			continue
 		}
 
+		// If the domain is too long to test for wildcards, it won't appear in the results
+		if len(domain)+randomSubdomainLength > 253 {
+			continue
+		}
+
 		ctx := detectionTaskContext{
 			results: results,
 

pkg/wildcarder/wildcarder_test.go

@@ -140,6 +140,23 @@ func TestFilterSimpleWildcard(t *testing.T) {
 	assert.ElementsMatch(t, []string{"test.com"}, roots)
 }
 
+func TestFilterDomainTooLong(t *testing.T) {
+	domainTooLong := strings.Repeat("a", 229) + ".test.com"
+
+	resolver := newFakeResolver()
+	resolver.addAnswer("test.com", []DNSAnswer{{Type: resolvermt.TypeA, Answer: "192.168.0.5"}})
+	resolver.addAnswer(domainTooLong, []DNSAnswer{{Type: resolvermt.TypeA, Answer: "192.168.0.5"}})
+	resolver.addAnswer("random.test.com", []DNSAnswer{{Type: resolvermt.TypeA, Answer: "192.168.0.5"}})
+
+	wc := New(1, 1, WithResolver(resolver))
+	overrideWildcardTest(wc)
+
+	domains, roots := wc.Filter(strings.NewReader(domainTooLong))
+
+	assert.Empty(t, domains)
+	assert.Empty(t, roots)
+}
+
 func TestFilterSimpleWildcardCNAME(t *testing.T) {
 	resolver := newFakeResolver()
 	resolver.addAnswer("test.com", []DNSAnswer{{Type: resolvermt.TypeCNAME, Answer: "example.com"}})