From: Nigel Jones <nigel@nigelj.com>
Date: Thu, 22 Oct 2015 10:16:15 +0000 (+1300)
Subject: Prevent SIGFPE in wrandom routine - Fixes Issue #2794
X-Git-Tag: dnsdist-1.0.0-alpha1~252^2~4^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d289442518bd8ce13ce141bb1164f9c4b12f1ce1;p=pdns

Prevent SIGFPE in wrandom routine - Fixes Issue #2794

When a selected pool is empty (no servers in the default pool) or all servers in
the pool are marked as down, a Floating Point Exception will trigger as the
situation isn't caught.
---

diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index 5ef526fd2..bb3596d08 100644
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -262,6 +262,11 @@ shared_ptr<DownstreamState> wrandom(const NumberedServerVector& servers, const C
 
     }
   }
+
+  // Catch poss & sum are empty to avoid SIGFPE
+  if(poss.empty())
+    return shared_ptr<DownstreamState>();
+
   int r = random() % sum;
   auto p = upper_bound(poss.begin(), poss.end(),r, [](int r, const decltype(poss)::value_type& a) { return  r < a.first;});
   if(p==poss.end())