func StartServerProxy()

in internal/mock/alloydb.go [260:318]
57 lines of code
7 McCabe index (conditional complexity)

func StartServerProxy(t *testing.T, inst FakeAlloyDBInstance) func() {
	pool := x509.NewCertPool()
	pool.AddCert(inst.rootCACert)
	tryListen := func(t *testing.T, attempts int) net.Listener {
		var (
			ln  net.Listener
			err error
		)
		for i := 0; i < attempts; i++ {
			ln, err = tls.Listen("tcp", ":5433", &tls.Config{
				Certificates: []tls.Certificate{
					{
						Certificate: [][]byte{inst.serverCert.Raw, inst.rootCACert.Raw},
						PrivateKey:  inst.serverKey,
						Leaf:        inst.serverCert,
					},
				},
				ServerName: "127.0.0.1",
				ClientAuth: tls.RequireAndVerifyClientCert,
				ClientCAs:  pool,
			})
			if err != nil {
				t.Log("listener failed to start, waiting 100ms")
				time.Sleep(500 * time.Millisecond)
				continue
			}
			return ln
		}
		t.Fatalf("failed to start listener: %v", err)
		return nil
	}
	ln := tryListen(t, 10)
	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			default:
				conn, err := ln.Accept()
				if err != nil {
					return
				}
				if err := metadataExchange(conn); err != nil {
					conn.Close()
					return
				}

				// Database protocol takes over from here.
				conn.Write([]byte(inst.name))
				conn.Close()
			}
		}
	}()
	return func() {
		cancel()
		ln.Close()
	}
}