Ensure double-starting or stopping DiscoveryManager and MDNSManager doesn't cause side-effects, since we do this when Home is pressed while streaming

Limelight/Network/DiscoveryManager.m

@@ -70,6 +70,10 @@
 }
 
 - (void) startDiscovery {
+    if (shouldDiscover) {
+        return;
+    }
+    
     Log(LOG_I, @"Starting discovery");
     shouldDiscover = YES;
     [_mdnsMan searchForHosts];
@@ -79,6 +83,10 @@
 }
 
 - (void) stopDiscovery {
+    if (!shouldDiscover) {
+        return;
+    }
+    
     Log(LOG_I, @"Stopping discovery");
     shouldDiscover = NO;
     [_mdnsMan stopSearching];
@@ -87,10 +95,18 @@
 
 - (void) stopDiscoveryBlocking {
     Log(LOG_I, @"Stopping discovery and waiting for workers to stop");
+    
+    if (shouldDiscover) {
         shouldDiscover = NO;
         [_mdnsMan stopSearching];
         [_opQueue cancelAllOperations];
+    }
+    
+    // Ensure we always wait, just in case discovery
+    // was stopped already but in an async manner that
+    // left operations in progress.
     [_opQueue waitUntilAllOperationsAreFinished];
+    
     Log(LOG_I, @"All discovery workers stopped");
 }
 

Limelight/Network/MDNSManager.m

@@ -23,6 +23,8 @@ static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
     
     self.callback = callback;
     
+    scanActive = FALSE;
+    
     mDNSBrowser = [[NSNetServiceBrowser alloc] init];
     [mDNSBrowser setDelegate:self];
     
@@ -33,12 +35,20 @@ static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
 }
 
 - (void) searchForHosts {
+    if (scanActive) {
+        return;
+    }
+    
     Log(LOG_I, @"Starting mDNS discovery");
     scanActive = TRUE;
     [mDNSBrowser searchForServicesOfType:NV_SERVICE_TYPE inDomain:@""];
 }
 
 - (void) stopSearching {
+    if (!scanActive) {
+        return;
+    }
+    
     Log(LOG_I, @"Stopping mDNS discovery");
     scanActive = FALSE;
     [mDNSBrowser stop];