Only init our locking function if Python didnt

Adds quite a bit of complexity, might be better to set ours unconditionally but still import _ssl so that it doesn't overwrite ours at some point later.
pyca · Dec 31, 2013 · 80108a4 · 80108a4
1 parent afe1007
commit 80108a4
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Showing 3 changed files with 34 additions and 2 deletions.
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
@@ -168,8 +168,15 @@ def _ensure_ffi_initialized(cls):
         cls.ffi = ffi
         cls.lib = lib
 
-        res = cls.lib.Cryptography_setup_locking()
-        assert res == 0
+        try:
+            __import__("_ssl")
+            raise ImportError
+        except ImportError:
+            pass
+
+        if cls.lib.CRYPTO_get_locking_callback() == cls.ffi.NULL:
+            res = cls.lib.Cryptography_setup_locking()
+            assert res == 0
 
         cls.lib.OpenSSL_add_all_algorithms()
         cls.lib.SSL_load_error_strings()

diff --git a/cryptography/hazmat/backends/openssl/threads.py b/cryptography/hazmat/backends/openssl/threads.py
@@ -19,7 +19,10 @@
 """
 
 FUNCTIONS = """
+void (*CRYPTO_get_locking_callback(void))(int, int, const char *, int);
+void CRYPTO_set_locking_callback(void (*func)(int, int, const char *, int));
 static int Cryptography_setup_locking();
+static void (*Cryptography_locking_function_ptr)(int, int, const char *, int);
 """
 
 MACROS = """
@@ -200,6 +203,8 @@
     }
 }
 
+static void (*Cryptography_locking_function_ptr)
+    (int, int, const char *, int) = Cryptography_locking_function;
 
 static int Cryptography_setup_locking() {
     unsigned int i;

diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
@@ -100,6 +100,26 @@ def test_handle_unknown_error(self):
                 0
             )
 
+    def test_locking_callback_set(self):
+        b = Backend()
+
+        locking_cb = b.lib.CRYPTO_get_locking_callback()
+        assert locking_cb != b.ffi.NULL
+
+        # emulate import _ssl not setting this for some reason
+        b.lib.CRYPTO_set_locking_callback(b.ffi.NULL)
+
+        # force cffi to reinit
+        Backend.ffi = None
+        Backend.lib = None
+
+        # now it should get set to our one
+        b = Backend()
+        locking_cb = b.lib.CRYPTO_get_locking_callback()
+
+        assert locking_cb != b.ffi.NULL
+        assert locking_cb == b.lib.Cryptography_locking_function_ptr
+
     def test_threads(self):
         b = Backend()