From 557d7631d26e51415a3ba5efbe8dff7b058d0508 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 18 Jul 2016 15:00:26 +0200
Subject: [PATCH] dnsdist: Prevent the use of "any" addresses for downstream
 server

Otherwise the corresponding `DownstreamState`'s FD is -1 (needed
for 'client' mode) and we loop endlessly on `recvfrom()` returning -1.
Reported by Sander Smeenk.
---
 pdns/dnsdist-lua.cc | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/pdns/dnsdist-lua.cc b/pdns/dnsdist-lua.cc
index ebd6e41889..0fc8c57e7e 100644
--- a/pdns/dnsdist-lua.cc
+++ b/pdns/dnsdist-lua.cc
@@ -194,14 +194,20 @@ vector<std::function<void(void)>> setupLua(bool client, const std::string& confi
 			}
 			ComboAddress sourceAddr;
 			unsigned int sourceItf = 0;
-			if(auto address = boost::get<string>(&pvars)) {
+			if(auto addressStr = boost::get<string>(&pvars)) {
+			  ComboAddress address(*addressStr, 53);
 			  std::shared_ptr<DownstreamState> ret;
+			  if(IsAnyAddress(address)) {
+			    g_outputBuffer="Error creating new server: invalid address for a downstream server.";
+			    errlog("Error creating new server: %s is not a valid address for a downstream server", *addressStr);
+			    return ret;
+			  }
 			  try {
-			    ret=std::make_shared<DownstreamState>(ComboAddress(*address, 53));
+			    ret=std::make_shared<DownstreamState>(address);
 			  }
 			  catch(std::exception& e) {
 			    g_outputBuffer="Error creating new server: "+string(e.what());
-			    errlog("Error creating new server with address %s: %s", *address, e.what());
+			    errlog("Error creating new server with address %s: %s", addressStr, e.what());
 			    return ret;
 			  }
 
@@ -280,8 +286,14 @@ vector<std::function<void(void)>> setupLua(bool client, const std::string& confi
 			}
 
 			std::shared_ptr<DownstreamState> ret;
+			ComboAddress address(boost::get<string>(vars["address"]), 53);
+			if(IsAnyAddress(address)) {
+			  g_outputBuffer="Error creating new server: invalid address for a downstream server.";
+			  errlog("Error creating new server: %s is not a valid address for a downstream server", boost::get<string>(vars["address"]));
+			  return ret;
+			}
 			try {
-			  ret=std::make_shared<DownstreamState>(ComboAddress(boost::get<string>(vars["address"]), 53), sourceAddr, sourceItf);
+			  ret=std::make_shared<DownstreamState>(address, sourceAddr, sourceItf);
 			}
 			catch(std::exception& e) {
 			  g_outputBuffer="Error creating new server: "+string(e.what());
-- 
2.47.2