ssl: add SSLSocket#sigalg, #peer_sigalg, #group

These methods are useful to test post-quantum cryptography (PQC) cases.

Author: junaruga

ext/openssl/extconf.rb

@@ -156,9 +156,16 @@ def find_openssl_library
 have_func("EVP_PKEY_eq(NULL, NULL)", evp_h)
 have_func("EVP_PKEY_dup(NULL)", evp_h)
 
+# added in 3.2.0
+have_func("SSL_get0_group_name(NULL)", ssl_h)
+
 # added in 3.4.0
 have_func("TS_VERIFY_CTX_set0_certs(NULL, NULL)", ts_h)
 
+# added in 3.5.0
+have_func("SSL_get0_signature_name(NULL, NULL)", ssl_h)
+have_func("SSL_get0_peer_signature_name(NULL, NULL)", ssl_h)
+
 Logging::message "=== Checking done. ===\n"
 
 # Append flags from environment variables.

ext/openssl/ossl_ssl.c

@@ -2644,6 +2644,68 @@ ossl_ssl_tmp_key(VALUE self)
 	return Qnil;
     return ossl_pkey_new(key);
 }
+
+#ifdef HAVE_SSL_GET0_SIGNATURE_NAME
+/*
+ * call-seq:
+ *    ssl.sigalg => String
+ *
+ * Returns the signature algorithm name, the IANA name of the signature scheme
+ * used by the local to sign the TLS handshake.
+ */
+static VALUE
+ossl_ssl_get_sigalg(VALUE self)
+{
+    SSL *ssl;
+    const char *name;
+
+    GetSSL(self, ssl);
+    if (!SSL_get0_signature_name(ssl, &name))
+        return Qnil;
+    return rb_str_new_cstr(name);
+}
+
+#endif
+
+#ifdef HAVE_SSL_GET0_PEER_SIGNATURE_NAME
+/*
+ * call-seq:
+ *    ssl.peer_sigalg => String
+ *
+ * Returns the signature algorithm name, the IANA name of the signature scheme
+ * used by the peer to sign the TLS handshake.
+ */
+static VALUE
+ossl_ssl_get_peer_sigalg(VALUE self)
+{
+    SSL *ssl;
+    const char *name;
+
+    GetSSL(self, ssl);
+    if (!SSL_get0_peer_signature_name(ssl, &name))
+        return Qnil;
+    return rb_str_new_cstr(name);
+}
+#endif
+
+#ifdef HAVE_SSL_GET0_GROUP_NAME
+/*
+ * call-seq:
+ *    ssl.group => String
+ *
+ * Returns the name of the group that was used for the key agreement of the
+ * current TLS session establishment.
+ */
+static VALUE
+ossl_ssl_get_group(VALUE self)
+{
+    SSL *ssl;
+
+    GetSSL(self, ssl);
+    return rb_str_new_cstr(SSL_get0_group_name(ssl));
+}
+#endif
+
 #endif /* !defined(OPENSSL_NO_SOCK) */
 
 void
@@ -3067,6 +3129,15 @@ Init_ossl_ssl(void)
 # ifdef OSSL_USE_NEXTPROTONEG
     rb_define_method(cSSLSocket, "npn_protocol", ossl_ssl_npn_protocol, 0);
 # endif
+#ifdef HAVE_SSL_GET0_SIGNATURE_NAME
+    rb_define_method(cSSLSocket, "sigalg", ossl_ssl_get_sigalg, 0);
+#endif
+#ifdef HAVE_SSL_GET0_PEER_SIGNATURE_NAME
+    rb_define_method(cSSLSocket, "peer_sigalg", ossl_ssl_get_peer_sigalg, 0);
+#endif
+#ifdef HAVE_SSL_GET0_GROUP_NAME
+    rb_define_method(cSSLSocket, "group", ossl_ssl_get_group, 0);
+#endif
 
     rb_define_const(mSSL, "VERIFY_NONE", INT2NUM(SSL_VERIFY_NONE));
     rb_define_const(mSSL, "VERIFY_PEER", INT2NUM(SSL_VERIFY_PEER));

test/openssl/test_ssl.rb

@@ -2088,6 +2088,8 @@ def test_set_groups_tls12
       server_connect(port, ctx) { |ssl|
         cs = ssl.cipher[0]
         assert_match (/\AECDH/), cs
+        # SSL_get0_group_name() is supported on OpenSSL 3.2 or later.
+        assert_equal "secp384r1", ssl.group if openssl?(3, 2, 0)
         assert_equal "secp384r1", ssl.tmp_key.group.curve_name
         ssl.puts "abc"; assert_equal "abc\n", ssl.gets
       }
@@ -2127,6 +2129,8 @@ def test_set_groups_tls13
 
       server_connect(port, ctx) { |ssl|
         assert_equal "TLSv1.3", ssl.ssl_version
+        # SSL_get0_group_name() is supported on OpenSSL 3.2 or later.
+        assert_equal "secp384r1", ssl.group if openssl?(3, 2, 0)
         assert_equal "secp384r1", ssl.tmp_key.group.curve_name
         ssl.puts "abc"; assert_equal "abc\n", ssl.gets
       }
@@ -2213,6 +2217,41 @@ def test_export_keying_material
     end
   end
 
+  def test_get_sigalg
+    # SSL_get0_signature_name() not supported
+    # SSL_get0_peer_signature_name() not supported
+    return unless openssl?(3, 5, 0)
+
+    server_proc = -> (ctx, ssl) {
+      assert_equal('rsa_pss_rsae_sha256', ssl.sigalg)
+      assert_nil(ssl.peer_sigalg)
+
+      readwrite_loop(ctx, ssl)
+    }
+    start_server(server_proc: server_proc) do |port|
+      cli_ctx = OpenSSL::SSL::SSLContext.new
+      server_connect(port, cli_ctx) do |ssl|
+        assert_nil(ssl.sigalg)
+        assert_equal('rsa_pss_rsae_sha256', ssl.peer_sigalg)
+        ssl.puts "abc"; ssl.gets
+      end
+    end
+  end
+
+  def test_group
+    # SSL_get0_group_name() not supported
+    return unless openssl?(3, 2, 0)
+
+    start_server do |port|
+      cli_ctx = OpenSSL::SSL::SSLContext.new
+      cli_ctx.groups = "X25519"
+      server_connect(port, cli_ctx) do |ssl|
+        assert_equal('x25519', ssl.group)
+        ssl.puts "abc"; ssl.gets
+      end
+    end
+  end
+
   private
 
   def server_connect(port, ctx = nil)