From c52dd6afc57cd374e011e904804c0f07ef38104c Mon Sep 17 00:00:00 2001
From: Pieter Lexis <pieter.lexis@powerdns.com>
Date: Wed, 4 May 2016 19:18:01 +0200
Subject: [PATCH] Prevent launching identical backends

This catches configuration bugs (mostly when includes are used) where a
line `launch=backend` and a line `launch+=backend` occur in the sum of
the configuration.

Closes #3615
---
 pdns/dnsbackend.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pdns/dnsbackend.cc b/pdns/dnsbackend.cc
index a7b4d016b5..ac728e7605 100644
--- a/pdns/dnsbackend.cc
+++ b/pdns/dnsbackend.cc
@@ -134,6 +134,10 @@ void BackendMakerClass::launch(const string &instr)
   vector<string> parts;
   stringtok(parts,instr,", ");
 
+  for (const auto part : parts)
+    if (count(parts.begin(), parts.end(), part) > 1)
+      throw ArgException("Refusing to launch multiple backends with the same name '" + part + "', verify all 'launch' statements in your configuration");
+
   for(vector<string>::const_iterator i=parts.begin();i!=parts.end();++i) {
     const string &part=*i;
 
-- 
2.47.2