bpo-43794: OpenSSL 3.0.0: set OP_IGNORE_UNEXPECTED_EOF by default (GH-25309)

Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit 6f37ebc)

Co-authored-by: Christian Heimes <christian@python.org>

Author: miss-islington

Doc/library/ssl.rst

@@ -886,6 +886,14 @@ Constants
 
    .. versionadded:: 3.6
 
+.. data:: OP_IGNORE_UNEXPECTED_EOF
+
+   Ignore unexpected shutdown of TLS connections.
+
+   This option is only available with OpenSSL 3.0.0 and later.
+
+   .. versionadded:: 3.10
+
 .. data:: HAS_ALPN
 
    Whether the OpenSSL library has built-in support for the *Application-Layer

Lib/test/test_ssl.py

@@ -143,6 +143,7 @@ def data_file(*name):
 OP_SINGLE_ECDH_USE = getattr(ssl, "OP_SINGLE_ECDH_USE", 0)
 OP_CIPHER_SERVER_PREFERENCE = getattr(ssl, "OP_CIPHER_SERVER_PREFERENCE", 0)
 OP_ENABLE_MIDDLEBOX_COMPAT = getattr(ssl, "OP_ENABLE_MIDDLEBOX_COMPAT", 0)
+OP_IGNORE_UNEXPECTED_EOF = getattr(ssl, "OP_IGNORE_UNEXPECTED_EOF", 0)
 
 # Ubuntu has patched OpenSSL and changed behavior of security level 2
 # see https://bugs.python.org/issue41561#msg389003
@@ -1161,7 +1162,8 @@ def test_options(self):
         # SSLContext also enables these by default
         default |= (OP_NO_COMPRESSION | OP_CIPHER_SERVER_PREFERENCE |
                     OP_SINGLE_DH_USE | OP_SINGLE_ECDH_USE |
-                    OP_ENABLE_MIDDLEBOX_COMPAT)
+                    OP_ENABLE_MIDDLEBOX_COMPAT |
+                    OP_IGNORE_UNEXPECTED_EOF)
         self.assertEqual(default, ctx.options)
         ctx.options |= ssl.OP_NO_TLSv1
         self.assertEqual(default | ssl.OP_NO_TLSv1, ctx.options)

Misc/NEWS.d/next/Library/2021-04-09-16-14-22.bpo-43794.-1XPDH.rst

@@ -0,0 +1 @@
+Add :data:`ssl.OP_IGNORE_UNEXPECTED_EOF` constants (OpenSSL 3.0.0)

Modules/_ssl.c

@@ -3214,6 +3214,10 @@ _ssl__SSLContext_impl(PyTypeObject *type, int proto_version)
 #endif
 #ifdef SSL_OP_SINGLE_ECDH_USE
     options |= SSL_OP_SINGLE_ECDH_USE;
+#endif
+#ifdef SSL_OP_IGNORE_UNEXPECTED_EOF
+    /* Make OpenSSL 3.0.0 behave like 1.1.1 */
+    options |= SSL_OP_IGNORE_UNEXPECTED_EOF;
 #endif
     SSL_CTX_set_options(self->ctx, options);
 
@@ -6273,6 +6277,10 @@ PyInit__ssl(void)
     PyModule_AddIntConstant(m, "OP_NO_RENEGOTIATION",
                             SSL_OP_NO_RENEGOTIATION);
 #endif
+#ifdef SSL_OP_IGNORE_UNEXPECTED_EOF
+    PyModule_AddIntConstant(m, "OP_IGNORE_UNEXPECTED_EOF",
+                            SSL_OP_IGNORE_UNEXPECTED_EOF);
+#endif
 
 #ifdef X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT
     PyModule_AddIntConstant(m, "HOSTFLAG_ALWAYS_CHECK_SUBJECT",