From b137e60b2a93ce0e6740fa85d6392414cd65a1db Mon Sep 17 00:00:00 2001
From: Andrew Stucki <andrew.stucki@hashicorp.com>
Date: Fri, 17 Feb 2023 17:14:39 +0000
Subject: [PATCH] backport of commit 01ca6e268bd43597d3876f6736a954433e4eb644

---
 agent/xds/delta.go   | 7 +++++++
 agent/xds/testing.go | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/agent/xds/delta.go b/agent/xds/delta.go
index 5a1ef17d2445..de4a450de246 100644
--- a/agent/xds/delta.go
+++ b/agent/xds/delta.go
@@ -47,6 +47,13 @@ type ADSDeltaStream = envoy_discovery_v3.AggregatedDiscoveryService_DeltaAggrega
 
 // DeltaAggregatedResources implements envoy_discovery_v3.AggregatedDiscoveryServiceServer
 func (s *Server) DeltaAggregatedResources(stream ADSDeltaStream) error {
+	// this guard is mainly for our tests where we sometimes nil out the
+	// server stream, any use of the stream after we nil it causes
+	// pretty much all of the below code to panic.
+	if stream == nil {
+		return nil
+	}
+
 	defer s.activeStreams.Increment(stream.Context())()
 
 	// a channel for receiving incoming requests
diff --git a/agent/xds/testing.go b/agent/xds/testing.go
index 967a96e6acd7..1e090091972a 100644
--- a/agent/xds/testing.go
+++ b/agent/xds/testing.go
@@ -227,6 +227,10 @@ func (e *TestEnvoy) Close() error {
 	// unblock the recv chans to simulate recv errors when client disconnects
 	if e.deltaStream != nil && e.deltaStream.recvCh != nil {
 		close(e.deltaStream.recvCh)
+		// TODO: This is causing a bunch of panics in testing code due to inflight
+		// requests attempting to grab a context from a stream that's nil. Added
+		// some defensive code in the xDS handler, but really, this should get fixed
+		// so we no longer have a data-race
 		e.deltaStream = nil
 	}
 	if e.cancel != nil {