Merge pull request #256 from projectdiscovery/proxy-fallback-tcp

if udp fails, fallback to tcp connection

Author: Mzack9999

client.go

@@ -85,6 +85,20 @@ func NewWithOptions(options Options) (*Client, error) {
 		doh.WithProxy(options.Proxy), // no-op if empty
 	)
 
+	// If proxy is specified, force TCP for all resolvers
+	if options.Proxy != "" {
+		for i, resolver := range parsedBaseResolvers {
+			if networkResolver, ok := resolver.(*NetworkResolver); ok && networkResolver.Protocol == UDP {
+				// Convert UDP resolvers to TCP when proxy is specified
+				parsedBaseResolvers[i] = &NetworkResolver{
+					Protocol: TCP,
+					Host:     networkResolver.Host,
+					Port:     networkResolver.Port,
+				}
+			}
+		}
+	}
+
 	udpDialer := &net.Dialer{LocalAddr: options.GetLocalAddr(UDP)}
 	tcpDialer := &net.Dialer{LocalAddr: options.GetLocalAddr(TCP)}
 	dotDialer := &net.Dialer{LocalAddr: options.GetLocalAddr(TCP)}
@@ -426,7 +440,17 @@ func (c *Client) queryMultiple(host string, requestTypes []uint16, resolver Reso
 				} else {
 					switch r.Protocol {
 					case TCP:
-						resp, _, err = c.tcpClient.Exchange(msg, resolver.String())
+						if c.tcpProxy != nil {
+							var tcpConn *dns.Conn
+							tcpConn, err = c.dialWithProxy(c.tcpProxy, "tcp", resolver.String())
+							if err != nil {
+								break
+							}
+							defer tcpConn.Close()
+							resp, _, err = c.tcpClient.ExchangeWithConn(msg, tcpConn)
+						} else {
+							resp, _, err = c.tcpClient.Exchange(msg, resolver.String())
+						}
 					case UDP:
 						if c.options.ConnectionPoolThreads > 1 {
 							if udpConnPool, ok := c.udpConnPool.Get(resolver.String()); ok {

client_test.go

@@ -55,7 +55,7 @@ func TestConsistentResolve(t *testing.T) {
 
 	var last string
 	for i := 0; i < 10; i++ {
-		d, err := client.Resolve("example.com")
+		d, err := client.Resolve("scanme.sh")
 		require.Nil(t, err, "could not resolve dns")
 
 		if last != "" {
@@ -69,7 +69,7 @@ func TestConsistentResolve(t *testing.T) {
 func TestUDP(t *testing.T) {
 	client, _ := New([]string{"1.1.1.1:53", "udp:8.8.8.8"}, 5)
 
-	d, err := client.QueryMultiple("example.com", []uint16{dns.TypeA})
+	d, err := client.QueryMultiple("scanme.sh", []uint16{dns.TypeA})
 	require.Nil(t, err)
 
 	// From current dig result
@@ -79,7 +79,7 @@ func TestUDP(t *testing.T) {
 func TestTCP(t *testing.T) {
 	client, _ := New([]string{"tcp:1.1.1.1:53", "tcp:8.8.8.8"}, 5)
 
-	d, err := client.QueryMultiple("example.com", []uint16{dns.TypeA})
+	d, err := client.QueryMultiple("scanme.sh", []uint16{dns.TypeA})
 	require.Nil(t, err)
 
 	// From current dig result
@@ -89,7 +89,7 @@ func TestTCP(t *testing.T) {
 func TestDOH(t *testing.T) {
 	client, _ := New([]string{"doh:https://doh.opendns.com/dns-query:post", "doh:https://doh.opendns.com/dns-query:get"}, 5)
 
-	d, err := client.QueryMultiple("example.com", []uint16{dns.TypeA})
+	d, err := client.QueryMultiple("scanme.sh", []uint16{dns.TypeA})
 	require.Nil(t, err)
 
 	// From current dig result
@@ -99,7 +99,7 @@ func TestDOH(t *testing.T) {
 func TestDOT(t *testing.T) {
 	client, _ := New([]string{"dot:dns.google:853", "dot:1dot1dot1dot1.cloudflare-dns.com"}, 5)
 
-	d, err := client.QueryMultiple("example.com", []uint16{dns.TypeA})
+	d, err := client.QueryMultiple("scanme.sh", []uint16{dns.TypeA})
 	require.Nil(t, err)
 
 	// From current dig result

doh/doh_client_test.go

@@ -11,7 +11,7 @@ func TestConsistentResolve(t *testing.T) {
 	client := New()
 	var lastAnswer string
 	for i := 0; i < 10; i++ {
-		d, err := client.Query("example.com", A)
+		d, err := client.Query("scanme.sh", A)
 		require.Nil(t, err, "could not resolve dns")
 		if lastAnswer == "" {
 			lastAnswer = d.Answer[0].Data

options.go

@@ -10,6 +10,18 @@ import (
 var (
 	ErrMaxRetriesZero = errors.New("retries must be at least 1")
 	ErrResolversEmpty = errors.New("resolvers list must not be empty")
+
+	BaseResolvers = []string{
+		"1.1.1.1:53",
+		"1.0.0.1:53",
+		"8.8.8.8:53",
+		"8.8.4.4:53",
+	}
+	DefaultOptions = Options{
+		BaseResolvers: BaseResolvers,
+		MaxRetries:    1,
+		Timeout:       3 * time.Second,
+	}
 )
 
 type Options struct {