From db94be13159cc8ac11e49544f089b5288c3c234f Mon Sep 17 00:00:00 2001
From: Dino Chiesa <dchiesa@google.com>
Date: Fri, 20 Sep 2024 15:17:35 -0700
Subject: [PATCH] add check for multiple fallbacks

---
 ...cate-servers.js => TD008-target-LB-servers.js} | 15 +++++++++++++++
 test/fixtures/resources/TD008/fail/t4.xml         | 14 ++++++++++++++
 test/fixtures/resources/TD008/pass/t4.xml         | 12 ++++++++++++
 3 files changed, 41 insertions(+)
 rename lib/package/plugins/{TD008-target-LB-duplicate-servers.js => TD008-target-LB-servers.js} (89%)
 create mode 100644 test/fixtures/resources/TD008/fail/t4.xml
 create mode 100644 test/fixtures/resources/TD008/pass/t4.xml

diff --git a/lib/package/plugins/TD008-target-LB-duplicate-servers.js b/lib/package/plugins/TD008-target-LB-servers.js
similarity index 89%
rename from lib/package/plugins/TD008-target-LB-duplicate-servers.js
rename to lib/package/plugins/TD008-target-LB-servers.js
index 3973885..dc82126 100644
--- a/lib/package/plugins/TD008-target-LB-duplicate-servers.js
+++ b/lib/package/plugins/TD008-target-LB-servers.js
@@ -43,6 +43,21 @@ const onTargetEndpoint = function (endpoint, cb) {
 
       if (loadBalancers.length == 1) {
         const loadBalancer = loadBalancers[0];
+        // check multiple fallbacks
+        const fallbacks = xpath.select(
+          "Server[IsFallback = 'true']",
+          loadBalancer
+        );
+        if (fallbacks.length > 1) {
+          endpoint.addMessage({
+            plugin,
+            line: loadBalancers[0].lineNumber,
+            column: loadBalancers[0].columnNumber,
+            message: "Multiple Server entries with IsFallback=true"
+          });
+          flagged = true;
+        }
+
         const servers = xpath.select("Server", loadBalancer);
         if (servers.length > 1) {
           const previouslyDetected = [];
diff --git a/test/fixtures/resources/TD008/fail/t4.xml b/test/fixtures/resources/TD008/fail/t4.xml
new file mode 100644
index 0000000..4dc231a
--- /dev/null
+++ b/test/fixtures/resources/TD008/fail/t4.xml
@@ -0,0 +1,14 @@
+<TargetEndpoint name="default">
+    <HTTPTargetConnection>
+      <LoadBalancer>
+         <Server name="server1"/>
+         <!-- two servers marked fallback will fail the TD008 check -->
+         <Server name="server2">
+           <IsFallback>true</IsFallback>
+         </Server>
+         <Server name="server3">
+           <IsFallback>true</IsFallback>
+         </Server>
+      </LoadBalancer>
+    </HTTPTargetConnection>
+</TargetEndpoint>
diff --git a/test/fixtures/resources/TD008/pass/t4.xml b/test/fixtures/resources/TD008/pass/t4.xml
new file mode 100644
index 0000000..8f11d85
--- /dev/null
+++ b/test/fixtures/resources/TD008/pass/t4.xml
@@ -0,0 +1,12 @@
+<TargetEndpoint name="default">
+    <HTTPTargetConnection>
+      <LoadBalancer>
+         <Server name="server1"/>
+         <Server name="server2"/>
+         <!-- single fallback is OK -->
+         <Server name="server3">
+           <IsFallback>true</IsFallback>
+         </Server>
+      </LoadBalancer>
+    </HTTPTargetConnection>
+</TargetEndpoint>