From 4eab88c0179f7ffa70065b8f543af04f7a3187e9 Mon Sep 17 00:00:00 2001
From: Frank Denis <github@pureftpd.org>
Date: Thu, 17 Sep 2020 00:44:37 +0200
Subject: [PATCH] plugin_dns64: don't send queries to self

Fixes #1477
---
 dnscrypt-proxy/plugin_dns64.go     | 32 ++++++++++++++++--------------
 dnscrypt-proxy/plugin_query_log.go |  4 +++-
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/dnscrypt-proxy/plugin_dns64.go b/dnscrypt-proxy/plugin_dns64.go
index 5aaa4f23e4..442683b91c 100644
--- a/dnscrypt-proxy/plugin_dns64.go
+++ b/dnscrypt-proxy/plugin_dns64.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net"
 	"sync"
+	"time"
 
 	"github.com/jedisct1/dlog"
 	"github.com/miekg/dns"
@@ -21,6 +22,7 @@ type PluginDNS64 struct {
 	pref64         []*net.IPNet
 	dns64Resolvers []string
 	ipv4Resolver   string
+	proxy          *Proxy
 }
 
 func (plugin *PluginDNS64) Name() string {
@@ -34,6 +36,7 @@ func (plugin *PluginDNS64) Description() string {
 func (plugin *PluginDNS64) Init(proxy *Proxy) error {
 	plugin.ipv4Resolver = proxy.listenAddresses[0] //recursively to ourselves
 	plugin.pref64Mutex = new(sync.RWMutex)
+	plugin.proxy = proxy
 
 	if len(proxy.dns64Prefixes) != 0 {
 		plugin.pref64Mutex.RLock()
@@ -65,26 +68,29 @@ func (plugin *PluginDNS64) Reload() error {
 }
 
 func (plugin *PluginDNS64) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
-	if !hasAAAAQuestion(pluginsState.questionMsg) || hasAAAAAnswer(msg) {
+	if hasAAAAAnswer(msg) {
 		return nil
 	}
 
-	questions := msg.Question
-	if len(questions) != 1 {
-		return nil
-	}
-	question := questions[0]
-	if question.Qclass != dns.ClassINET {
+	question := pluginsState.questionMsg.Question[0]
+	if question.Qclass != dns.ClassINET || question.Qtype != dns.TypeAAAA {
 		return nil
 	}
 
-	msgA := new(dns.Msg)
+	msgA := pluginsState.questionMsg.Copy()
 	msgA.SetQuestion(question.Name, dns.TypeA)
+	msgAPacket, err := msgA.Pack()
+	if err != nil {
+		return err
+	}
 
-	client := new(dns.Client)
-	resp, _, err := client.Exchange(msgA, plugin.ipv4Resolver)
+	respPacket := plugin.proxy.processIncomingQuery("trampoline", plugin.proxy.mainProto, msgAPacket, nil, nil, time.Now())
+	resp := dns.Msg{}
+	if err := resp.Unpack(respPacket); err != nil {
+		return err
+	}
 
-	if err != nil || resp == nil || resp.Rcode != dns.RcodeSuccess {
+	if err != nil || resp.Rcode != dns.RcodeSuccess {
 		return nil
 	}
 
@@ -134,10 +140,6 @@ func (plugin *PluginDNS64) Eval(pluginsState *PluginsState, msg *dns.Msg) error
 	return nil
 }
 
-func hasAAAAQuestion(msg *dns.Msg) bool {
-	return msg.Question[0].Qtype == dns.TypeAAAA
-}
-
 func hasAAAAAnswer(msg *dns.Msg) bool {
 	for _, answer := range msg.Answer {
 		if answer.Header().Rrtype == dns.TypeAAAA {
diff --git a/dnscrypt-proxy/plugin_query_log.go b/dnscrypt-proxy/plugin_query_log.go
index 5a806647b8..36de29db10 100644
--- a/dnscrypt-proxy/plugin_query_log.go
+++ b/dnscrypt-proxy/plugin_query_log.go
@@ -58,8 +58,10 @@ func (plugin *PluginQueryLog) Eval(pluginsState *PluginsState, msg *dns.Msg) err
 	var clientIPStr string
 	if pluginsState.clientProto == "udp" {
 		clientIPStr = (*pluginsState.clientAddr).(*net.UDPAddr).IP.String()
-	} else {
+	} else if pluginsState.clientProto == "tcp" {
 		clientIPStr = (*pluginsState.clientAddr).(*net.TCPAddr).IP.String()
+	} else {
+		clientIPStr = "-"
 	}
 	qName := pluginsState.qName