{ config, lib, pkgs, ... }: with lib; let cfg = config.services.kresd; package = pkgs.knot-resolver; configFile = pkgs.writeText "kresd.conf" cfg.extraConfig; in { meta.maintainers = [ maintainers.vcunat /* upstream developer */ ]; ###### interface options.services.kresd = { enable = mkOption { type = types.bool; default = false; description = '' Whether to enable knot-resolver domain name server. DNSSEC validation is turned on by default. You can run sudo nc -U /run/kresd/control and give commands interactively to kresd. ''; }; extraConfig = mkOption { type = types.lines; default = ""; description = '' Extra lines to be added verbatim to the generated configuration file. ''; }; cacheDir = mkOption { type = types.path; default = "/var/cache/kresd"; description = '' Directory for caches. They are intended to survive reboots. ''; }; interfaces = mkOption { type = with types; listOf str; default = [ "::1" "127.0.0.1" ]; description = '' What addresses the server should listen on. (UDP+TCP 53) ''; }; listenTLS = mkOption { type = with types; listOf str; default = []; example = [ "198.51.100.1:853" "[2001:db8::1]:853" "853" ]; description = '' Addresses on which kresd should provide DNS over TLS (see RFC 7858). For detailed syntax see ListenStream in man systemd.socket. ''; }; # TODO: perhaps options for more common stuff like cache size or forwarding }; ###### implementation config = mkIf cfg.enable { environment.etc."kresd.conf".source = configFile; # not required users.users = singleton { name = "kresd"; uid = config.ids.uids.kresd; group = "kresd"; description = "Knot-resolver daemon user"; }; users.groups = singleton { name = "kresd"; gid = config.ids.gids.kresd; }; systemd.sockets.kresd = rec { wantedBy = [ "sockets.target" ]; before = wantedBy; listenStreams = map # Syntax depends on being IPv6 or IPv4. (iface: if elem ":" (stringToCharacters iface) then "[${iface}]:53" else "${iface}:53") cfg.interfaces; socketConfig = { ListenDatagram = listenStreams; FreeBind = true; FileDescriptorName = "dns"; }; }; systemd.sockets.kresd-tls = mkIf (cfg.listenTLS != []) rec { wantedBy = [ "sockets.target" ]; before = wantedBy; partOf = [ "kresd.socket" ]; listenStreams = cfg.listenTLS; socketConfig = { FileDescriptorName = "tls"; FreeBind = true; Service = "kresd.service"; }; }; systemd.sockets.kresd-control = rec { wantedBy = [ "sockets.target" ]; before = wantedBy; partOf = [ "kresd.socket" ]; listenStreams = [ "/run/kresd/control" ]; socketConfig = { FileDescriptorName = "control"; Service = "kresd.service"; SocketMode = "0660"; # only root user/group may connect and control kresd }; }; systemd.tmpfiles.rules = [ "d '${cfg.cacheDir}' 0770 kresd kresd - -" ]; systemd.services.kresd = { description = "Knot-resolver daemon"; serviceConfig = { User = "kresd"; Type = "notify"; WorkingDirectory = cfg.cacheDir; Restart = "on-failure"; Sockets = [ "kresd.socket" "kresd-control.socket" ] ++ optional (cfg.listenTLS != []) "kresd-tls.socket"; }; # Trust anchor goes from dns-root-data by default. script = '' exec '${package}/bin/kresd' --config '${configFile}' --forks=1 ''; requires = [ "kresd.socket" ]; }; }; }