Feature: add PTR domain name resolution

Signed-off-by: Fxzx micah <[email protected]>

dns/hosts.go

@@ -21,6 +21,7 @@ func LoadHosts() *trie.DomainTrie {
 	t := trie.New()
 	h := map[string][]net.IP{}
 	p := map[string][]string{}
+	n := map[string][]net.IP{}
 
 	sc := bufio.NewScanner(f)
 	for sc.Scan() {
@@ -36,22 +37,23 @@ func LoadHosts() *trie.DomainTrie {
 			continue
 		}
 
-		name := strings.Fields(line)
+		names := strings.Fields(line)
 		// ignore blank lines
-		if len(name) == 0 {
+		if len(names) == 0 {
 			continue
 		}
 
-		ip := net.ParseIP(name[0])
+		ip := net.ParseIP(names[0])
 		// ignore lines that do not start with IP
 		if ip == nil {
 			continue
 		}
 
 		ptr := transIpToPtr(ip)
-		for _, name := range name[1:] {
+		for _, name := range names[1:] {
 			h[name] = append(h[name], ip)
 			p[ptr] = append(p[ptr], name+".")
+			n[ptr] = append(n[ptr], h[name]...)
 		}
 	}
 
@@ -63,6 +65,10 @@ func LoadHosts() *trie.DomainTrie {
 		t.Insert(ptr, names)
 	}
 
+	for ptr, ips := range n {
+		t.Insert(ptr, ips)
+	}
+
 	return t
 }
 

test/dns_test.go

@@ -47,6 +47,14 @@ dns:
 	rr, err = exchange("127.0.0.1:8553", "2606-4700-4700--1111.sslip.io", dns.TypeAAAA)
 	assert.NoError(t, err)
 	assert.Empty(t, rr)
+
+	rr, err := exchange("127.0.0.1:8553", "127.0.0.1", dns.TypePTR)
+	assert.NoError(t, err)
+	assert.Empty(t, rr)
+
+	rr, err = exchange("127.0.0.1:8553", "::1", dns.TypePTR)
+	assert.NoError(t, err)
+	assert.Empty(t, rr)
 }
 
 func TestClash_DNSHostAndFakeIP(t *testing.T) {