ssl: rework SSLContext#ssl_version=

Reimplement SSLContext#ssl_version= as a wrapper around
SSLContext#min_version= and #max_version=.

SSLContext#ssl_version= used to call SSL_CTX_set_ssl_version() which
replaces the SSL method used for the connections created from the SSL
context. This is mainly used for forcing a specific SSL/TLS protocol
version.

As of OpenSSL 1.1.0, however, use of the version-specific SSL methods
such as TLSv1_method() is deprecated. Follow the current recommendation
-- to use the generic SSL method always and to control the supported
version range by SSL_CTX_set_{min,max}_proto_version(). Actually, we
have already started doing a similar thing when the extension is
compiled with OpenSSL 1.1.0.

OpenSSL::SSL::SSLContext::METHODS, which contained the possible names of
SSL methods, is not useful anymore. It is now deprecate_constant-ed.

Author: rhenium

ext/openssl/extconf.rb

@@ -104,11 +104,6 @@ def find_openssl_library
 
 Logging::message "=== Checking for OpenSSL features... ===\n"
 # compile options
-
-# SSLv2 and SSLv3 may be removed in future versions of OpenSSL, and even macros
-# like OPENSSL_NO_SSL2 may not be defined.
-have_func("SSLv2_method")
-have_func("SSLv3_method")
 have_func("RAND_egd")
 engines = %w{builtin_engines openbsd_dev_crypto dynamic 4758cca aep atalla chil
              cswift nuron sureware ubsec padlock capi gmp gost cryptodev aesni}

ext/openssl/ossl_ssl.c

@@ -46,44 +46,6 @@ static ID id_i_cert_store, id_i_ca_file, id_i_ca_path, id_i_verify_mode,
 	  id_i_verify_hostname;
 static ID id_i_io, id_i_context, id_i_hostname;
 
-/*
- * SSLContext class
- */
-static const struct {
-    const char *name;
-    const SSL_METHOD *(*func)(void);
-    int version;
-} ossl_ssl_method_tab[] = {
-#if defined(HAVE_SSL_CTX_SET_MIN_PROTO_VERSION)
-#define OSSL_SSL_METHOD_ENTRY(name, version) \
-    { #name,          TLS_method, version }, \
-    { #name"_server", TLS_server_method, version }, \
-    { #name"_client", TLS_client_method, version }
-#else
-#define OSSL_SSL_METHOD_ENTRY(name, version) \
-    { #name,          name##_method, version }, \
-    { #name"_server", name##_server_method, version }, \
-    { #name"_client", name##_client_method, version }
-#endif
-#if !defined(OPENSSL_NO_SSL2) && !defined(OPENSSL_NO_SSL2_METHOD) && defined(HAVE_SSLV2_METHOD)
-    OSSL_SSL_METHOD_ENTRY(SSLv2, SSL2_VERSION),
-#endif
-#if !defined(OPENSSL_NO_SSL3) && !defined(OPENSSL_NO_SSL3_METHOD) && defined(HAVE_SSLV3_METHOD)
-    OSSL_SSL_METHOD_ENTRY(SSLv3, SSL3_VERSION),
-#endif
-#if !defined(OPENSSL_NO_TLS1) && !defined(OPENSSL_NO_TLS1_METHOD)
-    OSSL_SSL_METHOD_ENTRY(TLSv1, TLS1_VERSION),
-#endif
-#if !defined(OPENSSL_NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1_METHOD)
-    OSSL_SSL_METHOD_ENTRY(TLSv1_1, TLS1_1_VERSION),
-#endif
-#if !defined(OPENSSL_NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2_METHOD)
-    OSSL_SSL_METHOD_ENTRY(TLSv1_2, TLS1_2_VERSION),
-#endif
-    OSSL_SSL_METHOD_ENTRY(SSLv23, 0),
-#undef OSSL_SSL_METHOD_ENTRY
-};
-
 static int ossl_ssl_ex_vcb_idx;
 static int ossl_ssl_ex_ptr_idx;
 static int ossl_sslctx_ex_ptr_idx;
@@ -148,51 +110,6 @@ ossl_sslctx_s_alloc(VALUE klass)
     return obj;
 }
 
-/*
- * call-seq:
- *    ctx.ssl_version = :TLSv1
- *    ctx.ssl_version = "SSLv23_client"
- *
- * Sets the SSL/TLS protocol version for the context. This forces connections to
- * use only the specified protocol version.
- *
- * You can get a list of valid versions with OpenSSL::SSL::SSLContext::METHODS
- */
-static VALUE
-ossl_sslctx_set_ssl_version(VALUE self, VALUE ssl_method)
-{
-    SSL_CTX *ctx;
-    const char *s;
-    VALUE m = ssl_method;
-    int i;
-
-    GetSSLCTX(self, ctx);
-    if (RB_TYPE_P(ssl_method, T_SYMBOL))
-	m = rb_sym2str(ssl_method);
-    s = StringValueCStr(m);
-    for (i = 0; i < numberof(ossl_ssl_method_tab); i++) {
-        if (strcmp(ossl_ssl_method_tab[i].name, s) == 0) {
-#if defined(HAVE_SSL_CTX_SET_MIN_PROTO_VERSION)
-	    int version = ossl_ssl_method_tab[i].version;
-#endif
-	    const SSL_METHOD *method = ossl_ssl_method_tab[i].func();
-
-	    if (SSL_CTX_set_ssl_version(ctx, method) != 1)
-		ossl_raise(eSSLError, "SSL_CTX_set_ssl_version");
-
-#if defined(HAVE_SSL_CTX_SET_MIN_PROTO_VERSION)
-	    if (!SSL_CTX_set_min_proto_version(ctx, version))
-		ossl_raise(eSSLError, "SSL_CTX_set_min_proto_version");
-	    if (!SSL_CTX_set_max_proto_version(ctx, version))
-		ossl_raise(eSSLError, "SSL_CTX_set_max_proto_version");
-#endif
-	    return ssl_method;
-        }
-    }
-
-    ossl_raise(rb_eArgError, "unknown SSL method `%"PRIsVALUE"'.", m);
-}
-
 static int
 parse_proto_version(VALUE str)
 {
@@ -2333,9 +2250,6 @@ ossl_ssl_tmp_key(VALUE self)
 void
 Init_ossl_ssl(void)
 {
-    int i;
-    VALUE ary;
-
 #if 0
     mOSSL = rb_define_module("OpenSSL");
     eOSSLError = rb_define_class_under(mOSSL, "OpenSSLError", rb_eStandardError);
@@ -2632,7 +2546,6 @@ Init_ossl_ssl(void)
 
     rb_define_alias(cSSLContext, "ssl_timeout", "timeout");
     rb_define_alias(cSSLContext, "ssl_timeout=", "timeout=");
-    rb_define_method(cSSLContext, "ssl_version=", ossl_sslctx_set_ssl_version, 1);
     rb_define_private_method(cSSLContext, "set_minmax_proto_version",
 			     ossl_sslctx_set_minmax_proto_version, 2);
     rb_define_method(cSSLContext, "ciphers",     ossl_sslctx_get_ciphers, 0);
@@ -2702,14 +2615,6 @@ Init_ossl_ssl(void)
     rb_define_method(cSSLContext, "options",     ossl_sslctx_get_options, 0);
     rb_define_method(cSSLContext, "options=",     ossl_sslctx_set_options, 1);
 
-    ary = rb_ary_new2(numberof(ossl_ssl_method_tab));
-    for (i = 0; i < numberof(ossl_ssl_method_tab); i++) {
-        rb_ary_push(ary, ID2SYM(rb_intern(ossl_ssl_method_tab[i].name)));
-    }
-    rb_obj_freeze(ary);
-    /* The list of available SSL/TLS methods */
-    rb_define_const(cSSLContext, "METHODS", ary);
-
     /*
      * Document-class: OpenSSL::SSL::SSLSocket
      */

lib/openssl/ssl.rb

@@ -181,6 +181,51 @@ def max_version=(version)
         set_minmax_proto_version(@min_proto_version ||= nil, version)
         @max_proto_version = version
       end
+
+      # call-seq:
+      #    ctx.ssl_version = :TLSv1
+      #    ctx.ssl_version = "SSLv23"
+      #
+      # Sets the SSL/TLS protocol version for the context. This forces
+      # connections to use only the specified protocol version. This is
+      # deprecated and only provided for backwards compatibility. Use
+      # #min_version= and #max_version= instead.
+      #
+      # === History
+      # As the name hints, this used to call the SSL_CTX_set_ssl_version()
+      # function which sets the SSL method used for connections created from
+      # the context. As of Ruby/OpenSSL 2.1, this accessor method is
+      # implemented to call #min_version= and #max_version= instead.
+      def ssl_version=(meth)
+        meth = meth.to_s if meth.is_a?(Symbol)
+        if /(?<type>_client|_server)\z/ =~ meth
+          meth = $`
+          if $VERBOSE
+            warn "#{caller(1)[0]}: method type #{type.inspect} is ignored"
+          end
+        end
+        version = METHODS_MAP[meth.intern] or
+          raise ArgumentError, "unknown SSL method `%s'" % meth
+        set_minmax_proto_version(version, version)
+        @min_proto_version = @max_proto_version = version
+      end
+
+      METHODS_MAP = {
+        SSLv23: 0,
+        SSLv2: OpenSSL::SSL::SSL2_VERSION,
+        SSLv3: OpenSSL::SSL::SSL3_VERSION,
+        TLSv1: OpenSSL::SSL::TLS1_VERSION,
+        TLSv1_1: OpenSSL::SSL::TLS1_1_VERSION,
+        TLSv1_2: OpenSSL::SSL::TLS1_2_VERSION,
+      }.freeze
+      private_constant :METHODS_MAP
+
+      # The list of available SSL/TLS methods. This constant is only provided
+      # for backwards compatibility.
+      METHODS = METHODS_MAP.flat_map { |name,|
+        [name, :"#{name}_client", :"#{name}_server"]
+      }.freeze
+      deprecate_constant :METHODS
     end
 
     module SocketForwarder

test/test_ssl.rb

@@ -969,6 +969,17 @@ def test_options_disable_versions
     end
   end
 
+  def test_ssl_methods_constant
+    EnvUtil.suppress_warning { # Deprecated in v2.1.0
+      base = [:TLSv1_2, :TLSv1_1, :TLSv1, :SSLv3, :SSLv2, :SSLv23]
+      base.each do |name|
+        assert_include OpenSSL::SSL::SSLContext::METHODS, name
+        assert_include OpenSSL::SSL::SSLContext::METHODS, :"#{name}_client"
+        assert_include OpenSSL::SSL::SSLContext::METHODS, :"#{name}_server"
+      end
+    }
+  end
+
   def test_renegotiation_cb
     num_handshakes = 0
     renegotiation_cb = Proc.new { |ssl| num_handshakes += 1 }