From fc37ff0f2c05776c378511deee11beead73fe3e8 Mon Sep 17 00:00:00 2001
From: Eugene Venter <eugene@catalyst.net.nz>
Date: Wed, 26 May 2021 13:46:06 +1200
Subject: [PATCH] endpoint/domain_filter.go: add MatchParent DomainFilter
 method

---
 endpoint/domain_filter.go      | 25 +++++++++++++
 endpoint/domain_filter_test.go | 66 ++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/endpoint/domain_filter.go b/endpoint/domain_filter.go
index 91445e862..539bafd73 100644
--- a/endpoint/domain_filter.go
+++ b/endpoint/domain_filter.go
@@ -106,6 +106,31 @@ func matchRegex(regex *regexp.Regexp, negativeRegex *regexp.Regexp, domain strin
 	return regex.MatchString(strippedDomain)
 }
 
+// MatchParent checks wether DomainFilter matches a given parent domain.
+func (df DomainFilter) MatchParent(domain string) bool {
+	if !df.IsConfigured() {
+		return true
+	}
+
+	for _, filter := range df.Filters {
+		if strings.HasPrefix(filter, ".") {
+			// We don't check parents if the filter is prefixed with "."
+			continue
+		}
+
+		if filter == "" {
+			return true
+		}
+
+		strippedDomain := strings.ToLower(strings.TrimSuffix(domain, "."))
+		if strings.HasSuffix(filter, "."+strippedDomain) && !matchFilter(df.exclude, domain, false) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // IsConfigured returns true if DomainFilter is configured, false otherwise
 func (df DomainFilter) IsConfigured() bool {
 	if df.regex != nil && df.regex.String() != "" {
diff --git a/endpoint/domain_filter_test.go b/endpoint/domain_filter_test.go
index ecf8ca318..64647f71c 100644
--- a/endpoint/domain_filter_test.go
+++ b/endpoint/domain_filter_test.go
@@ -296,6 +296,72 @@ func TestDomainFilterMatchWithEmptyFilter(t *testing.T) {
 	}
 }
 
+func TestDomainFilterMatchParent(t *testing.T) {
+	parentMatchTests := []domainFilterTest{
+		{
+			[]string{"a.example.com."},
+			[]string{},
+			[]string{"example.com"},
+			true,
+		},
+		{
+			[]string{" a.example.com "},
+			[]string{},
+			[]string{"example.com"},
+			true,
+		},
+		{
+			[]string{""},
+			[]string{},
+			[]string{"example.com"},
+			true,
+		},
+		{
+			[]string{".a.example.com."},
+			[]string{},
+			[]string{"example.com"},
+			false,
+		},
+		{
+			[]string{"a.example.com.", "b.example.com"},
+			[]string{},
+			[]string{"example.com"},
+			true,
+		},
+		{
+			[]string{"a.example.com"},
+			[]string{},
+			[]string{"b.example.com"},
+			false,
+		},
+		{
+			[]string{"example.com"},
+			[]string{},
+			[]string{"example.com"},
+			false,
+		},
+		{
+			[]string{"example.com"},
+			[]string{},
+			[]string{"anexample.com"},
+			false,
+		},
+		{
+			[]string{""},
+			[]string{},
+			[]string{""},
+			true,
+		},
+	}
+	for i, tt := range parentMatchTests {
+		domainFilter := NewDomainFilterWithExclusions(tt.domainFilter, tt.exclusions)
+		for _, domain := range tt.domains {
+			assert.Equal(t, tt.expected, domainFilter.MatchParent(domain), "should not fail: %v in test-case #%v", domain, i)
+			assert.Equal(t, tt.expected, domainFilter.MatchParent(domain+"."), "should not fail: %v in test-case #%v", domain+".", i)
+		}
+	}
+}
+
 func TestRegexDomainFilter(t *testing.T) {
 	for i, tt := range regexDomainFilterTests {
 		domainFilter := NewRegexDomainFilter(tt.regex, tt.regexExclusion)