1 files changed, 41 insertions, 0 deletions
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 5e5438a708..a2f95911d9 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -1371,6 +1371,47 @@ func TestTransportDialPreservesNetOpProxyError(t *testing.T) {
 	}
 }
 
+// Issue 36431: calls to RoundTrip should not mutate t.ProxyConnectHeader.
+//
+// (A bug caused dialConn to instead write the per-request Proxy-Authorization
+// header through to the shared Header instance, introducing a data race.)
+func TestTransportProxyDialDoesNotMutateProxyConnectHeader(t *testing.T) {
+	setParallel(t)
+	defer afterTest(t)
+
+	proxy := httptest.NewTLSServer(NotFoundHandler())
+	defer proxy.Close()
+	c := proxy.Client()
+
+	tr := c.Transport.(*Transport)
+	tr.Proxy = func(*Request) (*url.URL, error) {
+		u, _ := url.Parse(proxy.URL)
+		u.User = url.UserPassword("aladdin", "opensesame")
+		return u, nil
+	}
+	h := tr.ProxyConnectHeader
+	if h == nil {
+		h = make(Header)
+	}
+	tr.ProxyConnectHeader = make(Header, len(h))
+	for k, vals := range h {
+		tr.ProxyConnectHeader[k] = append([]string(nil), vals...)
+	}
+
+	req, err := NewRequest("GET", "https://golang.fake.tld/", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = c.Do(req)
+	if err == nil {
+		t.Errorf("unexpected Get success")
+	}
+
+	if !reflect.DeepEqual(tr.ProxyConnectHeader, h) {
+		t.Errorf("tr.ProxyConnectHeader = %v; want %v", tr.ProxyConnectHeader, h)
+	}
+}
+
 // TestTransportGzipRecursive sends a gzip quine and checks that the
 // client gets the same value back. This is more cute than anything,
 // but checks that we don't recurse forever, and checks that