check if ipv6 enabled before listen

kvmd/apps/__init__.py

@@ -656,7 +656,7 @@ def _get_config_scheme() -> dict:
 
         "ipmi": {
             "server": {
-                "host":    Option("::", type=valid_ip_or_host),
+                "host":    Option("",   type=valid_ip_or_host, if_empty=""),
                 "port":    Option(623,  type=valid_port),
                 "timeout": Option(10.0, type=valid_float_f01),
             },
@@ -684,7 +684,7 @@ def _get_config_scheme() -> dict:
             "keymap":       Option("/usr/share/kvmd/keymaps/en-us", type=valid_abs_file),
 
             "server": {
-                "host":        Option("::", type=valid_ip_or_host),
+                "host":        Option("",   type=valid_ip_or_host, if_empty=""),
                 "port":        Option(5900, type=valid_port),
                 "max_clients": Option(10,   type=valid_int_f1),
 

kvmd/apps/ipmi/server.py

@@ -41,6 +41,7 @@ from ...logging import get_logger
 from ...clients.kvmd import KvmdClient
 
 from ... import aiotools
+from ... import network
 
 from .auth import IpmiAuthManager
 
@@ -65,6 +66,8 @@ class IpmiServer(BaseIpmiServer):  # pylint: disable=too-many-instance-attribute
         sol_proxy_port: int,
     ) -> None:
 
+        host = network.get_listen_host(host)
+
         super().__init__(authdata=auth_manager, address=host, port=port)
 
         self.__auth_manager = auth_manager

kvmd/apps/vnc/server.py

@@ -47,6 +47,7 @@ from ...clients.streamer import BaseStreamerClient
 
 from ... import tools
 from ... import aiotools
+from ... import network
 
 from .rfb import RfbClient
 from .rfb.stream import rfb_format_remote
@@ -444,7 +445,7 @@ class VncServer:  # pylint: disable=too-many-instance-attributes
         vnc_auth_manager: VncAuthManager,
     ) -> None:
 
-        self.__host = host
+        self.__host = network.get_listen_host(host)
         self.__port = port
         self.__max_clients = max_clients
 

kvmd/network.py

@@ -0,0 +1,48 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main PiKVM daemon.                                           #
+#                                                                            #
+#    Copyright (C) 2018-2023  Maxim Devaev <mdevaev@gmail.com>               #
+#                                                                            #
+#    This program is free software: you can redistribute it and/or modify    #
+#    it under the terms of the GNU General Public License as published by    #
+#    the Free Software Foundation, either version 3 of the License, or       #
+#    (at your option) any later version.                                     #
+#                                                                            #
+#    This program is distributed in the hope that it will be useful,         #
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
+#    GNU General Public License for more details.                            #
+#                                                                            #
+#    You should have received a copy of the GNU General Public License       #
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#                                                                            #
+# ========================================================================== #
+
+
+import socket
+import errno
+
+
+# =====
+def is_ipv6_enabled() -> bool:
+    if not socket.has_ipv6:
+        # If the socket library has no support for IPv6,
+        # then the question is moot as we can't use IPv6 anyways.
+        return False
+    try:
+        with socket.socket(socket.AF_INET6, socket.SOCK_STREAM) as sock:
+            sock.bind(("::1", 0))
+        return True
+    except OSError as err:
+        if err.errno in [errno.EADDRNOTAVAIL, errno.EAFNOSUPPORT]:
+            return False
+        if err.errno == errno.EADDRINUSE:
+            return True
+        raise
+
+
+def get_listen_host(host: str) -> str:
+    if len(host) == 0:
+        return ("::" if is_ipv6_enabled() else "0.0.0.0")
+    return host