gh-94172: Remove ssl.PROTOCOL_SSLv2 dead code (#94312)

Remove dead code related to ssl.PROTOCOL_SSLv2. ssl.PROTOCOL_SSLv2
was already removed in Python 3.10.

In test_ssl, @requires_tls_version('SSLv2') always returned False.

Extract of the removed code: "OpenSSL has removed support for SSLv2".

Author: vstinner

Doc/library/ssl.rst

@@ -645,21 +645,6 @@ Constants
 
       Use :data:`PROTOCOL_TLS` instead.
 
-.. data:: PROTOCOL_SSLv2
-
-   Selects SSL version 2 as the channel encryption protocol.
-
-   This protocol is not available if OpenSSL is compiled with the
-   ``no-ssl2`` option.
-
-   .. warning::
-
-      SSL version 2 is insecure.  Its use is highly discouraged.
-
-   .. deprecated:: 3.6
-
-      OpenSSL has removed support for SSLv2.
-
 .. data:: PROTOCOL_SSLv3
 
    Selects SSL version 3 as the channel encryption protocol.
@@ -1438,11 +1423,10 @@ to speed up repeated connections from the same clients.
       The context is created with secure default values. The options
       :data:`OP_NO_COMPRESSION`, :data:`OP_CIPHER_SERVER_PREFERENCE`,
       :data:`OP_SINGLE_DH_USE`, :data:`OP_SINGLE_ECDH_USE`,
-      :data:`OP_NO_SSLv2` (except for :data:`PROTOCOL_SSLv2`),
+      :data:`OP_NO_SSLv2`,
       and :data:`OP_NO_SSLv3` (except for :data:`PROTOCOL_SSLv3`) are
       set by default. The initial cipher suite list contains only ``HIGH``
-      ciphers, no ``NULL`` ciphers and no ``MD5`` ciphers (except for
-      :data:`PROTOCOL_SSLv2`).
+      ciphers, no ``NULL`` ciphers and no ``MD5`` ciphers.
 
    .. deprecated:: 3.10
 

Lib/test/test_ssl.py

@@ -208,10 +208,6 @@ def has_tls_version(version):
     :param version: TLS version name or ssl.TLSVersion member
     :return: bool
     """
-    if version == "SSLv2":
-        # never supported and not even in TLSVersion enum
-        return False
-
     if isinstance(version, str):
         version = ssl.TLSVersion.__members__[version]
 
@@ -3129,37 +3125,10 @@ def test_ssl_cert_verify_error(self):
                     self.assertIn(msg, repr(e))
                     self.assertIn('certificate verify failed', repr(e))
 
-    @requires_tls_version('SSLv2')
-    def test_protocol_sslv2(self):
-        """Connecting to an SSLv2 server with various client options"""
-        if support.verbose:
-            sys.stdout.write("\n")
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_SSLv2, True)
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_SSLv2, True, ssl.CERT_OPTIONAL)
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_SSLv2, True, ssl.CERT_REQUIRED)
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_TLS, False)
-        if has_tls_version('SSLv3'):
-            try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_SSLv3, False)
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_TLSv1, False)
-        # SSLv23 client with specific SSL options
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_TLS, False,
-                           client_options=ssl.OP_NO_SSLv3)
-        try_protocol_combo(ssl.PROTOCOL_SSLv2, ssl.PROTOCOL_TLS, False,
-                           client_options=ssl.OP_NO_TLSv1)
-
     def test_PROTOCOL_TLS(self):
         """Connecting to an SSLv23 server with various client options"""
         if support.verbose:
             sys.stdout.write("\n")
-        if has_tls_version('SSLv2'):
-            try:
-                try_protocol_combo(ssl.PROTOCOL_TLS, ssl.PROTOCOL_SSLv2, True)
-            except OSError as x:
-                # this fails on some older versions of OpenSSL (0.9.7l, for instance)
-                if support.verbose:
-                    sys.stdout.write(
-                        " SSL2 client to SSL23 server test unexpectedly failed:\n %s\n"
-                        % str(x))
         if has_tls_version('SSLv3'):
             try_protocol_combo(ssl.PROTOCOL_TLS, ssl.PROTOCOL_SSLv3, False)
         try_protocol_combo(ssl.PROTOCOL_TLS, ssl.PROTOCOL_TLS, True)
@@ -3197,8 +3166,6 @@ def test_protocol_sslv3(self):
         try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_SSLv3, 'SSLv3')
         try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_SSLv3, 'SSLv3', ssl.CERT_OPTIONAL)
         try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_SSLv3, 'SSLv3', ssl.CERT_REQUIRED)
-        if has_tls_version('SSLv2'):
-            try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_SSLv2, False)
         try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_TLS, False,
                            client_options=ssl.OP_NO_SSLv3)
         try_protocol_combo(ssl.PROTOCOL_SSLv3, ssl.PROTOCOL_TLSv1, False)
@@ -3211,8 +3178,6 @@ def test_protocol_tlsv1(self):
         try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_TLSv1, 'TLSv1')
         try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_TLSv1, 'TLSv1', ssl.CERT_OPTIONAL)
         try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_TLSv1, 'TLSv1', ssl.CERT_REQUIRED)
-        if has_tls_version('SSLv2'):
-            try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_SSLv2, False)
         if has_tls_version('SSLv3'):
             try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_SSLv3, False)
         try_protocol_combo(ssl.PROTOCOL_TLSv1, ssl.PROTOCOL_TLS, False,
@@ -3225,8 +3190,6 @@ def test_protocol_tlsv1_1(self):
         if support.verbose:
             sys.stdout.write("\n")
         try_protocol_combo(ssl.PROTOCOL_TLSv1_1, ssl.PROTOCOL_TLSv1_1, 'TLSv1.1')
-        if has_tls_version('SSLv2'):
-            try_protocol_combo(ssl.PROTOCOL_TLSv1_1, ssl.PROTOCOL_SSLv2, False)
         if has_tls_version('SSLv3'):
             try_protocol_combo(ssl.PROTOCOL_TLSv1_1, ssl.PROTOCOL_SSLv3, False)
         try_protocol_combo(ssl.PROTOCOL_TLSv1_1, ssl.PROTOCOL_TLS, False,
@@ -3245,8 +3208,6 @@ def test_protocol_tlsv1_2(self):
         try_protocol_combo(ssl.PROTOCOL_TLSv1_2, ssl.PROTOCOL_TLSv1_2, 'TLSv1.2',
                            server_options=ssl.OP_NO_SSLv3|ssl.OP_NO_SSLv2,
                            client_options=ssl.OP_NO_SSLv3|ssl.OP_NO_SSLv2,)
-        if has_tls_version('SSLv2'):
-            try_protocol_combo(ssl.PROTOCOL_TLSv1_2, ssl.PROTOCOL_SSLv2, False)
         if has_tls_version('SSLv3'):
             try_protocol_combo(ssl.PROTOCOL_TLSv1_2, ssl.PROTOCOL_SSLv3, False)
         try_protocol_combo(ssl.PROTOCOL_TLSv1_2, ssl.PROTOCOL_TLS, False,

Modules/_ssl.c

@@ -138,9 +138,6 @@ extern const SSL_METHOD *TLSv1_2_method(void);
 #define INVALID_SOCKET (-1)
 #endif
 
-/* OpenSSL 1.1 does not have SSL 2.0 */
-#define OPENSSL_NO_SSL2
-
 /* Default cipher suites */
 #ifndef PY_SSL_DEFAULT_CIPHERS
 #define PY_SSL_DEFAULT_CIPHERS 1
@@ -5825,10 +5822,6 @@ sslmodule_init_constants(PyObject *m)
 #undef ADD_AD_CONSTANT
 
     /* protocol versions */
-#ifndef OPENSSL_NO_SSL2
-    PyModule_AddIntConstant(m, "PROTOCOL_SSLv2",
-                            PY_SSL_VERSION_SSL2);
-#endif
 #ifndef OPENSSL_NO_SSL3
     PyModule_AddIntConstant(m, "PROTOCOL_SSLv3",
                             PY_SSL_VERSION_SSL3);
@@ -5938,11 +5931,7 @@ sslmodule_init_constants(PyObject *m)
     addbool(m, "HAS_NPN", 0);
     addbool(m, "HAS_ALPN", 1);
 
-#if defined(SSL2_VERSION) && !defined(OPENSSL_NO_SSL2)
-    addbool(m, "HAS_SSLv2", 1);
-#else
     addbool(m, "HAS_SSLv2", 0);
-#endif
 
 #if defined(SSL3_VERSION) && !defined(OPENSSL_NO_SSL3)
     addbool(m, "HAS_SSLv3", 1);