First attempt at Kerberos support for the XGrid process starter

refs trac:345

This commit was SVN r11812.

The following Trac tickets were found above:
  Ticket 345 --> https://svn.open-mpi.org/trac/ompi/ticket/345

orte/mca/pls/xgrid/src/pls_xgrid_client.h

@@ -44,7 +44,6 @@
     opal_mutex_t state_mutex;
 
     XGConnection *connection;
-    XGTwoWayRandomAuthenticator *authenticator;
     XGController *controller;
     XGGrid *grid;
     int cleanup;
@@ -68,6 +67,8 @@
 -(void) setControllerHostnameAsCString: (char*) password;
 -(void) setCleanUp: (int) val;
 
+-(NSString*)servicePrincipal;
+
 /* interface for launch */
 -(int) connect;
 -(int) launchJob:(orte_jobid_t) jobid;

orte/mca/pls/xgrid/src/pls_xgrid_client.m

@@ -144,20 +144,41 @@ char **environ;
 }
 
 
+- (NSString *)servicePrincipal;
+{
+    NSString *servicePrincipal = [connection servicePrincipal];
+
+    if (servicePrincipal == nil) [NSString stringWithFormat:@"xgrid/%@", [connection name]];
+
+    return servicePrincipal;
+}
+
+
 /* interface for launch */
 -(int) connect
 {
     connection = [[[XGConnection alloc] initWithHostname: controller_hostname
 					portnumber:0] autorelease];
-    authenticator = [[[XGTwoWayRandomAuthenticator alloc] init] autorelease];
 
-    /* this seems to be hard coded */
-    [authenticator setUsername:@"one-xgrid-client"];
-    [authenticator setPassword:controller_password];
+    if (NULL == controller_password) {
+	XGGSSAuthenticator *authenticator = 
+	    [[[XGGSSAuthenticator alloc] init] autorelease];
+		
+	[authenticator setServicePrincipal:[self servicePrincipal]];
+	[connection setAuthenticator:authenticator];
+
+    } else {
+        XGTwoWayRandomAuthenticator *authenticator =
+	    [[[XGTwoWayRandomAuthenticator alloc] init] autorelease];
+
+	/* this seems to be hard coded */
+	[authenticator setUsername:@"one-xgrid-client"];
+	[authenticator setPassword:controller_password];
     
-    [connection setAuthenticator:authenticator];
+	[connection setAuthenticator:authenticator];
+    }
     [connection setDelegate: self];
-    
+
     /* get us connected */
     opal_mutex_lock(&state_mutex);
     [connection open];

orte/mca/pls/xgrid/src/pls_xgrid_component.m

@@ -137,8 +137,7 @@ orte_pls_xgrid_component_init(int *priority)
         return NULL;
     }
 
-    if (NULL == getenv("XGRID_CONTROLLER_HOSTNAME") ||
-        NULL == getenv("XGRID_CONTROLLER_PASSWORD")) {
+    if (NULL == getenv("XGRID_CONTROLLER_HOSTNAME")) {
 	opal_output(orte_pls_base.pls_output,
 		    "orte:pls:xgrid: not available: controller info not set");
         return NULL;