Retry connecting to Heimdal if the first try fails

In the Heimdal version of kadmin-backend, retry the kadmin connection
once if the first connection fails.  This is a workaround for a
transient networking error that we're seeing at Stanford and therefore
may not be fully appropriate for other sites.  Even on a successful
reconnect, this will cause some errors to be sent to standard error
due to the behavior of Heimdal::Kadm5.

diff --git a/NEWS b/NEWS
index cec6edecc841728ed1a54a4703e26600cc3e2cc6..a55b91905fa9ba7d13ddb4fc53f9740b0da9c70d 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,13 @@
 
 kadmin-remctl 3.3 (unreleased)
 
+    In the Heimdal version of kadmin-backend, retry the kadmin connection
+    once if the first connection fails.  This is a workaround for a
+    transient networking error that we're seeing at Stanford and therefore
+    may not be fully appropriate for other sites.  Even on a successful
+    reconnect, this will cause some errors to be sent to standard error
+    due to the behavior of Heimdal::Kadm5.
+
     When prompting for a username in passwd_change, strip any surrounding
     whitespace from that username before proceeding.
 

diff --git a/kadmin-backend-heim b/kadmin-backend-heim
index 10c4b3801a02748cc20acfec58f9f31d42ade420..b3f42378f10747e69c132d5e12a568e6e75d3511 100755 (executable)
--- a/kadmin-backend-heim
+++ b/kadmin-backend-heim
@@ -5,7 +5,7 @@
 # Written by Russ Allbery <rra@stanford.edu>
 # Heimdal port written by Jon Robertson <jonrober@stanford.edu>
 # Based heavily on work by Roland Schemers
-# Copyright 2003, 2007, 2008, 2009, 2010, 2011
+# Copyright 2003, 2007, 2008, 2009, 2010, 2011, 2013
 #     The Board of Trustees of the Leland Stanford Junior University
 #
 # Permission to use, copy, modify, and distribute this software and its
@@ -217,11 +217,27 @@ sub kadmin_handle {
     my ($instance) = @_;
     return $CONFIG{$instance}{handle} if exists $CONFIG{$instance}{handle};
 
-    my $kadmin =  Heimdal::Kadm5::Client->new(
-        Principal   => $CONFIG{$instance}{k5_admin},
-        Keytab      => $CONFIG{$instance}{k5_keytab},
-        RaiseErrors => 1,
-    );
+    # If the connection fails, retry once.
+    my $kadmin;
+    my $first = 1;
+  CONNECT:
+    {
+        local $SIG{__WARN__} = sub {};
+        $kadmin = eval {
+            Heimdal::Kadm5::Client->new(
+                Principal   => $CONFIG{$instance}{k5_admin},
+                Keytab      => $CONFIG{$instance}{k5_keytab},
+                RaiseErrors => 1,
+            );
+        };
+        if ($first && ($@ || !$kadmin)) {
+            $first = 0;
+            redo CONNECT;
+        }
+        if ($@ || !$kadmin) {
+            die;
+        }
+    }
     $CONFIG{$instance}{handle} = $kadmin;
     return $kadmin;
 }