check if ipv6 enabled before listen

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