From 74ec52d85758ad9da7a3abb24257511b22d74964 Mon Sep 17 00:00:00 2001
From: Eric Poulsen <eric@zyxod.com>
Date: Thu, 26 Oct 2017 21:17:35 -0700
Subject: [PATCH] extmod/modussl: Add finaliser support for ussl objects.

Per the comment found here
https://github.com/micropython/micropython-esp32/issues/209#issuecomment-339855157,
this patch adds finaliser code to prevent memory leaks from ussl objects,
which is especially useful when memory for a ussl context is allocated
outside the uPy heap.  This patch is in-line with the finaliser code found
in many modsocket implementations for various ports.

This feature is configured via MICROPY_PY_USSL_FINALISER and is disabled by
default because there may be issues using it when the ussl state *is*
allocated on the uPy heap, rather than externally.
---
 extmod/modussl_axtls.c   | 7 +++++++
 extmod/modussl_mbedtls.c | 7 +++++++
 py/mpconfig.h            | 2 ++
 3 files changed, 16 insertions(+)

diff --git a/extmod/modussl_axtls.c b/extmod/modussl_axtls.c
index 719a65cd1f..3ad65ebf32 100644
--- a/extmod/modussl_axtls.c
+++ b/extmod/modussl_axtls.c
@@ -51,7 +51,11 @@ struct ssl_args {
 STATIC const mp_obj_type_t ussl_socket_type;
 
 STATIC mp_obj_ssl_socket_t *socket_new(mp_obj_t sock, struct ssl_args *args) {
+#if MICROPY_PY_USSL_FINALISER
+    mp_obj_ssl_socket_t *o = m_new_obj_with_finaliser(mp_obj_ssl_socket_t);
+#else
     mp_obj_ssl_socket_t *o = m_new_obj(mp_obj_ssl_socket_t);
+#endif
     o->base.type = &ussl_socket_type;
     o->buf = NULL;
     o->bytes_left = 0;
@@ -178,6 +182,9 @@ STATIC const mp_rom_map_elem_t ussl_socket_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
     { MP_ROM_QSTR(MP_QSTR_setblocking), MP_ROM_PTR(&socket_setblocking_obj) },
     { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&socket_close_obj) },
+#if MICROPY_PY_USSL_FINALISER
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&socket_close_obj) },
+#endif
 };
 
 STATIC MP_DEFINE_CONST_DICT(ussl_socket_locals_dict, ussl_socket_locals_dict_table);
diff --git a/extmod/modussl_mbedtls.c b/extmod/modussl_mbedtls.c
index d7316cb4ae..59dceb6cff 100644
--- a/extmod/modussl_mbedtls.c
+++ b/extmod/modussl_mbedtls.c
@@ -111,7 +111,11 @@ int _mbedtls_ssl_recv(void *ctx, byte *buf, size_t len) {
 
 
 STATIC mp_obj_ssl_socket_t *socket_new(mp_obj_t sock, struct ssl_args *args) {
+#if MICROPY_PY_USSL_FINALISER
+    mp_obj_ssl_socket_t *o = m_new_obj_with_finaliser(mp_obj_ssl_socket_t);
+#else
     mp_obj_ssl_socket_t *o = m_new_obj(mp_obj_ssl_socket_t);
+#endif
     o->base.type = &ussl_socket_type;
 
     int ret;
@@ -272,6 +276,9 @@ STATIC const mp_rom_map_elem_t ussl_socket_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
     { MP_ROM_QSTR(MP_QSTR_setblocking), MP_ROM_PTR(&socket_setblocking_obj) },
     { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&socket_close_obj) },
+#if MICROPY_PY_USSL_FINALISER
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&socket_close_obj) },
+#endif
     { MP_ROM_QSTR(MP_QSTR_getpeercert), MP_ROM_PTR(&mod_ssl_getpeercert_obj) },
 };
 
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 1694a13601..6a32ea2a6f 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1109,6 +1109,8 @@ typedef double mp_float_t;
 
 #ifndef MICROPY_PY_USSL
 #define MICROPY_PY_USSL (0)
+// Whether to add finaliser code to ussl objects
+#define MICROPY_PY_USSL_FINALISER (0)
 #endif
 
 #ifndef MICROPY_PY_WEBSOCKET