redis_proxy: fix crash if catch_all_route is not defined (#29138)

Signed-off-by: deveshkandpal1224 <[email protected]>

changelogs/current.yaml

@@ -41,6 +41,9 @@ bug_fixes:
 - area: extension_discovery_service
   change: |
     Fixed a bug causing crash if ECDS is used with upstream HTTP filters.
+- area: redis_proxy
+  change: |
+    Fixed a bug causing crash if incoming redis key does not match against a prefix_route and catch_all_route is not defined.
 - area: tls
   change: |
     fixed a bug where handshake may fail when both private key provider and cert validation are set.

source/extensions/filters/network/redis_proxy/router_impl.cc

@@ -87,10 +87,14 @@ RouteSharedPtr PrefixRoutes::upstreamPool(std::string& key,
   } else {
     value = prefix_lookup_table_.findLongestPrefix(key.c_str());
   }
-
   if (value == nullptr) {
-    // prefix route not found, default to catch all route.
-    value = catch_all_route_;
+    // prefix route not found, check if catch_all_route is defined to fallback to.
+    if (catch_all_route_ != nullptr) {
+      value = catch_all_route_;
+    } else {
+      // no route found.
+      return value;
+    }
   }
 
   if (value->removePrefix()) {

test/extensions/filters/network/redis_proxy/router_impl_test.cc

@@ -50,6 +50,19 @@ createPrefixRoutes() {
   return prefix_routes;
 }
 
+TEST(PrefixRoutesTest, MissingCatchAll) {
+  Upstreams upstreams;
+  upstreams.emplace("fake_clusterA", std::make_shared<ConnPool::MockInstance>());
+  upstreams.emplace("fake_clusterB", std::make_shared<ConnPool::MockInstance>());
+
+  Runtime::MockLoader runtime_;
+
+  PrefixRoutes router(createPrefixRoutes(), std::move(upstreams), runtime_);
+
+  std::string key("c:bar");
+  EXPECT_EQ(nullptr, router.upstreamPool(key));
+}
+
 TEST(PrefixRoutesTest, RoutedToCatchAll) {
   auto upstream_c = std::make_shared<ConnPool::MockInstance>();