From ce715f38fcedf752220cd5056e1a3945330041fd Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Thu, 3 Dec 2020 09:34:08 +0100
Subject: [PATCH] rec: Handle failure to start the web server more gracefully

At this point we already have several threads so calling exit()
will cause problem by trying to destruct objects that are in use
by other threads, so call _exit() instead.
Also mention the web server in the error message so that the root
cause is easier to identify.
---
 pdns/pdns_recursor.cc | 14 +++++++-------
 pdns/ws-recursor.cc   |  7 +++++--
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index f3a5d17d68..6c9e641e97 100644
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -3658,7 +3658,7 @@ static bool trySendingQueryToWorker(unsigned int target, ThreadMSG* tmsg)
   auto& targetInfo = s_threadInfos[target];
   if(!targetInfo.isWorker) {
     g_log<<Logger::Error<<"distributeAsyncFunction() tried to assign a query to a non-worker thread"<<endl;
-    exit(1);
+    _exit(1);
   }
 
   const auto& tps = targetInfo.pipes;
@@ -3731,7 +3731,7 @@ void distributeAsyncFunction(const string& packet, const pipefunc_t& func)
 {
   if (!isDistributorThread()) {
     g_log<<Logger::Error<<"distributeAsyncFunction() has been called by a worker ("<<t_id<<")"<<endl;
-    exit(1);
+    _exit(1);
   }
 
   unsigned int hash = hashQuestion(packet.c_str(), packet.length(), g_disthashseed);
@@ -3813,7 +3813,7 @@ template<class T> T broadcastAccFunction(const boost::function<T*()>& func)
 {
   if (!isHandlerThread()) {
     g_log<<Logger::Error<<"broadcastAccFunction has been called by a worker ("<<t_id<<")"<<endl;
-    exit(1);
+    _exit(1);
   }
 
   unsigned int n = 0;
@@ -4068,7 +4068,7 @@ static FDMultiplexer* getMultiplexer()
     }
   }
   g_log<<Logger::Error<<"No working multiplexer found!"<<endl;
-  exit(1);
+  _exit(1);
 }
 
 
@@ -5086,9 +5086,9 @@ try
       try {
         rws = new RecursorWebServer(t_fdm);
       }
-      catch(PDNSException &e) {
-        g_log<<Logger::Error<<"Exception: "<<e.reason<<endl;
-        exit(99);
+      catch (const PDNSException &e) {
+        g_log<<Logger::Error<<"Unable to start the internal web server: "<<e.reason<<endl;
+        _exit(99);
       }
     }
     g_log<<Logger::Info<<"Enabled '"<< t_fdm->getName() << "' multiplexer"<<endl;
diff --git a/pdns/ws-recursor.cc b/pdns/ws-recursor.cc
index d80b689777..1c31c1f7fa 100644
--- a/pdns/ws-recursor.cc
+++ b/pdns/ws-recursor.cc
@@ -509,7 +509,8 @@ RecursorWebServer::RecursorWebServer(FDMultiplexer* fdm)
 {
   registerAllStats();
 
-  d_ws = std::unique_ptr<AsyncWebServer>(new AsyncWebServer(fdm, arg()["webserver-address"], arg().asNum("webserver-port")));
+  d_ws = make_unique<AsyncWebServer>(fdm, arg()["webserver-address"], arg().asNum("webserver-port"));
+
   d_ws->setApiKey(arg()["api-key"]);
   d_ws->setPassword(arg()["webserver-password"]);
   d_ws->setLogLevel(arg()["webserver-loglevel"]);
@@ -534,8 +535,10 @@ RecursorWebServer::RecursorWebServer(FDMultiplexer* fdm)
   d_ws->registerApiHandler("/api/v1/servers", &apiServer);
   d_ws->registerApiHandler("/api", &apiDiscovery);
 
-  for(const auto& u : g_urlmap) 
+  for (const auto& u : g_urlmap) {
     d_ws->registerWebHandler("/"+u.first, serveStuff);
+  }
+
   d_ws->registerWebHandler("/", serveStuff);
   d_ws->registerWebHandler("/metrics", prometheusMetrics);
   d_ws->go();
-- 
2.47.2