update condition to throw exception

Author: siddhijain

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/AadInstanceDiscoveryProvider.java

@@ -38,6 +38,8 @@ class AadInstanceDiscoveryProvider {
 
     private static final Logger log = LoggerFactory.getLogger(AadInstanceDiscoveryProvider.class);
 
+    //flag to check if instance discovery has failed
+    private static boolean instanceDiscoveryFailed = false;
     static ConcurrentHashMap<String, InstanceDiscoveryMetadataEntry> cache = new ConcurrentHashMap<>();
 
     static {
@@ -84,7 +86,7 @@ static InstanceDiscoveryMetadataEntry getMetadataEntry(URL authorityUrl,
         InstanceDiscoveryMetadataEntry result = cache.get(host);
 
         if (result == null) {
-            if(msalRequest.application().instanceDiscovery()){
+            if(msalRequest.application().instanceDiscovery() && !instanceDiscoveryFailed){
                 doInstanceDiscoveryAndCache(authorityUrl, validateAuthority, msalRequest, serviceBundle);
             } else {
                 // instanceDiscovery flag is set to False. Do not perform instanceDiscovery.
@@ -235,7 +237,12 @@ private static AadInstanceDiscoveryResponse sendInstanceDiscoveryRequest(URL aut
         httpResponse = executeRequest(instanceDiscoveryRequestUrl, msalRequest.headers().getReadonlyHeaderMap(), msalRequest, serviceBundle);
 
         if (httpResponse.statusCode() != HttpHelper.HTTP_STATUS_200) {
-            throw MsalServiceExceptionFactory.fromHttpResponse(httpResponse);
+            if(httpResponse.statusCode() == HttpHelper.HTTP_STATUS_400 && httpResponse.body().equals("invalid_instance")){
+                // instance discovery failed due to an invalid authority, throw an exception.
+                throw MsalServiceExceptionFactory.fromHttpResponse(httpResponse);
+            }
+            // instance discovery failed due to reasons other than an invalid authority, do not perform instance discovery again in this environment.
+            instanceDiscoveryFailed = true;
         }
 
 

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/HttpHelper.java

@@ -22,6 +22,9 @@ class HttpHelper {
     public static final int RETRY_DELAY_MS = 1000;
 
     public static final int HTTP_STATUS_200 = 200;
+
+    public static final int HTTP_STATUS_400 = 400;
+
     public static final int HTTP_STATUS_429 = 429;
     public static final int HTTP_STATUS_500 = 500;