Memleak tests (#3140)

* Bind a pair of mem functions.

* make these conditional

* do the conditional correctly

* move to the right section

* I'm not saying libressl should be illegal, but it is annoying

* sigh, typo

* first cut at memleak tests. doesn't work

* hack around the previous error, onto the next one

* drop the pointless restoration of the original functions

* Don't try to use the previous malloc functions.

The default malloc is CRYPTO_malloc which calls the custom ptr you provided, so it just recurses forever.

* flake8

* Get the code basically working

* flake8

* say the correct incantation

* Don't try to run on old OpenSSL

* Flushing this is a good idea

* Fixed a py2.7+ism

* GRRRRR

* WOrkaround for hilarity

* Revert "WOrkaround for hilarity"

This reverts commit 37b9f3b4ed4063eef5add3bb5d5dd592a007d439.

* Swap out these functions for the originals

* py3k fix

* flake8

* nonsense for windows

* py3k

* seperate stdout and stderr because py26 has a warning on stderr

* try writing this all out for windows

* useful error messages

* Debugging utility

* Avoid this mess, don't dlopen anything

* consistency

* Throw away this FFI entirely

* some useful comments

2 files changed, 49 insertions, 0 deletions

diff --git a/src/_cffi_src/openssl/crypto.py b/src/_cffi_src/openssl/crypto.py
index e33a3540..906dcacd 100644
--- a/src/_cffi_src/openssl/crypto.py
+++ b/src/_cffi_src/openssl/crypto.py
@@ -10,6 +10,7 @@ INCLUDES = """
 
 TYPES = """
 static const long Cryptography_HAS_LOCKING_CALLBACKS;
+static const long Cryptography_HAS_MEM_FUNCTIONS;
 
 static const int SSLEAY_VERSION;
 static const int SSLEAY_CFLAGS;
@@ -58,6 +59,16 @@ void OPENSSL_free(void *);
 
 /* This was removed in 1.1.0 */
 void CRYPTO_lock(int, int, const char *, int);
+
+/* Signature changed significantly in 1.1.0, only expose there for sanity */
+int Cryptography_CRYPTO_set_mem_functions(
+    void *(*)(size_t, const char *, int),
+    void *(*)(void *, size_t, const char *, int),
+    void (*)(void *, const char *, int));
+
+void *Cryptography_malloc_wrapper(size_t, const char *, int);
+void *Cryptography_realloc_wrapper(void *, size_t, const char *, int);
+void Cryptography_free_wrapper(void *, const char *, int);
 """
 
 CUSTOMIZATIONS = """
@@ -102,4 +113,39 @@ static const long CRYPTO_LOCK_SSL = 0;
 #endif
 void (*CRYPTO_lock)(int, int, const char *, int) = NULL;
 #endif
+
+#if CRYPTOGRAPHY_OPENSSL_LESS_THAN_110 || defined(LIBRESSL_VERSION_NUMBER)
+/* This function has a significantly different signature pre-1.1.0. since it is
+ * for testing only, we don't bother to expose it on older OpenSSLs.
+ */
+static const long Cryptography_HAS_MEM_FUNCTIONS = 0;
+int (*Cryptography_CRYPTO_set_mem_functions)(
+    void *(*)(size_t, const char *, int),
+    void *(*)(void *, size_t, const char *, int),
+    void (*)(void *, const char *, int)) = NULL;
+
+#else
+static const long Cryptography_HAS_MEM_FUNCTIONS = 1;
+
+int Cryptography_CRYPTO_set_mem_functions(
+    void *(*m)(size_t, const char *, int),
+    void *(*r)(void *, size_t, const char *, int),
+    void (*f)(void *, const char *, int)
+) {
+    return CRYPTO_set_mem_functions(m, r, f);
+}
+#endif
+
+void *Cryptography_malloc_wrapper(size_t size, const char *path, int line) {
+    return malloc(size);
+}
+
+void *Cryptography_realloc_wrapper(void *ptr, size_t size, const char *path,
+                                   int line) {
+    return realloc(ptr, size);
+}
+
+void Cryptography_free_wrapper(void *ptr, const char *path, int line) {
+    return free(ptr);
+}
 """
diff --git a/src/cryptography/hazmat/bindings/openssl/_conditional.py b/src/cryptography/hazmat/bindings/openssl/_conditional.py
index c95a9fe0..7f488ba0 100644
--- a/src/cryptography/hazmat/bindings/openssl/_conditional.py
+++ b/src/cryptography/hazmat/bindings/openssl/_conditional.py
@@ -291,4 +291,7 @@ CONDITIONAL_NAMES = {
     "Cryptography_HAS_EVP_PKEY_DHX": [
         "EVP_PKEY_DHX",
     ],
+    "Cryptography_HAS_MEM_FUNCTIONS": [
+        "Cryptography_CRYPTO_set_mem_functions",
+    ],
 }