From 905b09c38b6b8b08f0fe4a43b9b118366817bf0f Mon Sep 17 00:00:00 2001
From: ghciv6 <ghciv6@localhost>
Date: Wed, 20 May 2020 23:02:42 +0200
Subject: detect unreachable dns service in nslookup output (from
 bind-utils-9.8.2) prevent core if error_scan detects an error in a line
 without ':'


diff --git a/plugins/check_dns.c b/plugins/check_dns.c
index d4d0b88..b90f50e 100644
--- a/plugins/check_dns.c
+++ b/plugins/check_dns.c
@@ -202,7 +202,10 @@ main (int argc, char **argv)
     if (error_scan (chld_err.line[i]) != STATE_OK) {
       result = max_state (result, error_scan (chld_err.line[i]));
       msg = strchr(input_buffer, ':');
-      if(msg) msg++;
+      if(msg)
+         msg++;
+      else
+         msg = input_buffer;
     }
   }
 
@@ -348,6 +351,8 @@ error_scan (char *input_buffer)
   /* DNS server is not running... */
   else if (strstr (input_buffer, "No response from server"))
     die (STATE_CRITICAL, _("No response from DNS %s\n"), dns_server);
+  else if (strstr (input_buffer, "no servers could be reached"))
+    die (STATE_CRITICAL, _("No response from DNS %s\n"), dns_server);
 
   /* Host name is valid, but server doesn't have records... */
   else if (strstr (input_buffer, "No records"))
-- 
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