search domain discovery: add tests

Author: FR4NK-W

hinting/dns_search_domain_fallbacks.go

@@ -22,6 +22,15 @@ func domainsFromHostnames(hostnames []string) (domains []string) {
 				continue
 			}
 			domainString = strings.Join([]string{label, domainString}, ".")
+			// Filter out Effective ccTLDs (of the form "co.uk"), as we are only interested in the ETLD+1 domains
+			if 5 == len(domainString) && // TODO: complete TLD specific exceptions, or directly use PSL
+				(label == "co" ||
+					label == "ac" ||
+					label == "re" ||
+					label == "ne") {
+				// do not add country-code second-level ETLD domains to domains candidate list
+				continue
+			}
 			if !slices.Contains(domains, domainString) {
 				domains = append(domains, domainString)
 			}

hinting/dns_search_domain_fallbacks_test.go

@@ -0,0 +1,127 @@
+package hinting
+
+import (
+	"github.com/stretchr/testify/assert"
+	"net/netip"
+	"testing"
+)
+
+func TestReverseLookupDomains(t *testing.T) {
+
+	testCases := []struct {
+		name   string
+		values []struct {
+			ip     netip.Addr
+			domain string
+		}
+	}{
+		{
+			name: "ETHZ",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("129.132.19.216"), domain: "ethz.ch"},
+				{ip: netip.MustParseAddr("82.130.64.0"), domain: "ethz.ch"},
+				{ip: netip.MustParseAddr("148.187.192.0"), domain: "ethz.ch"},
+			},
+		},
+		{
+			name: "PU",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("66.180.178.131"), domain: "princeton.edu"},
+			},
+		},
+		{
+			name: "VU",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("128.143.33.137"), domain: "virginia.edu"},
+				{ip: netip.MustParseAddr("128.143.33.144"), domain: "virginia.edu"},
+			},
+		},
+		{
+			name: "SWITCH",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("130.59.31.80"), domain: "switch.ch"},
+			},
+		},
+		{
+			name: "KREONET",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("134.75.254.11"), domain: "kreonet.net"},
+				{ip: netip.MustParseAddr("134.75.254.12"), domain: "kreonet.net"},
+			},
+		},
+		{
+			name: "KU",
+			values: []struct {
+				ip     netip.Addr
+				domain string
+			}{
+				{ip: netip.MustParseAddr("163.152.6.10"), domain: "korea.ac.kr"},
+			},
+		},
+	}
+	for _, tc := range testCases {
+		t.Log(tc.name)
+		for _, v := range tc.values {
+			t.Log(v.ip)
+			res := reverseLookupDomains(v.ip)
+			t.Log(res)
+			assert.Subset(t, res, []string{v.domain}, "")
+		}
+	}
+}
+
+func TestDomainsFromHostnamesDerivation(t *testing.T) {
+
+	testCases := []struct {
+		name   string
+		values []struct {
+			hostnames []string
+			domains   []string
+		}
+	}{
+		{
+			name: "ETHZ",
+			values: []struct {
+				hostnames []string
+				domains   []string
+			}{
+				{hostnames: []string{"82-130-64-0.net4.ethz.ch."}, domains: []string{"net4.ethz.ch", "ethz.ch"}},
+				{hostnames: []string{"service-id-api-cd-dcz1-server-4-b.ethz.ch."}, domains: []string{"ethz.ch"}},
+			},
+		},
+		{
+			name: "ETHZ",
+			values: []struct {
+				hostnames []string
+				domains []string
+			}{
+				{hostnames: []string{"60.korea.ac.kr.", "sub.korea.ac.kr."}, domains: []string{"korea.ac.kr"}},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Log(tc.name)
+		for _, v := range tc.values {
+			t.Log(v.hostnames)
+			res := domainsFromHostnames(v.hostnames)
+			t.Log(res)
+			assert.EqualValues(t, v.domains, res, "")
+		}
+	}
+}