From eea4ffa4c39ffc29548ec623f029ae3ef9e47ad7 Mon Sep 17 00:00:00 2001
From: Hugo Santos <hugo@namespacelabs.com>
Date: Tue, 10 Sep 2024 16:52:54 +0200
Subject: [PATCH] servercore: introduced SharedMtlsGrpcListenerConfiguration
 that allows creating separate listeners that share the same mtls
 configuration.

---
 std/go/grpc/servercore/configurations.go | 10 ++++++++++
 std/go/grpc/servercore/listener.go       |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/std/go/grpc/servercore/configurations.go b/std/go/grpc/servercore/configurations.go
index 304ccd6275..a18a6bab14 100644
--- a/std/go/grpc/servercore/configurations.go
+++ b/std/go/grpc/servercore/configurations.go
@@ -16,6 +16,7 @@ import (
 var configConfigs = map[string]ListenerConfiguration{}
 
 type DefaultConfiguration struct{}
+type DefaultConfigurationWithSharedMtls struct{}
 
 type ListenerConfiguration interface {
 	CreateListener(context.Context, string, ListenOpts) (net.Listener, error)
@@ -27,6 +28,13 @@ type GrpcListenerConfiguration interface {
 	ServerOpts(string) []grpc.ServerOption
 }
 
+type SharedMtlsGrpcListenerConfiguration interface {
+	ListenerConfiguration
+
+	UseFoundationMTLSConfiguration()
+	ServerOpts(string) []grpc.ServerOption
+}
+
 func SetListenerConfiguration(name string, conf ListenerConfiguration) {
 	core.AssertNotRunning("SetServiceConfiguration")
 
@@ -48,3 +56,5 @@ func listenerConfiguration(name string) ListenerConfiguration {
 func (DefaultConfiguration) CreateListener(ctx context.Context, name string, opts ListenOpts) (net.Listener, error) {
 	return opts.CreateNamedListener(ctx, name)
 }
+
+func (DefaultConfigurationWithSharedMtls) UseFoundationMTLSConfiguration() {}
diff --git a/std/go/grpc/servercore/listener.go b/std/go/grpc/servercore/listener.go
index ca4c3340e5..52d3365e0a 100644
--- a/std/go/grpc/servercore/listener.go
+++ b/std/go/grpc/servercore/listener.go
@@ -157,6 +157,13 @@ func Listen(ctx context.Context, opts ListenOpts, registerServices func(Server))
 					x = append(x, grpc.Creds(creds))
 				}
 
+				serversByConfiguration[cfg.Name] = append(serversByConfiguration[cfg.Name], grpc.NewServer(x...))
+			} else if cgrp, ok := c.(SharedMtlsGrpcListenerConfiguration); ok {
+				x := append(slices.Clone(grpcopts), cgrp.ServerOpts(cfg.Name)...)
+				if tlsConfig != nil {
+					x = append(x, grpc.Creds(credentials.NewTLS(tlsConfig)))
+				}
+
 				serversByConfiguration[cfg.Name] = append(serversByConfiguration[cfg.Name], grpc.NewServer(x...))
 			} else {
 				return fnerrors.New("listener configuration for %q does not support grpc", cfg.Name)