about summary refs log tree commit diff
path: root/nixpkgs/nixos/modules/services/networking/kresd.nix
blob: fc516c01230a331dcaf932cfae834d8fd31c0c39 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
{ 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 <literal>sudo nc -U /run/kresd/control</literal>
        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" ];
    };
  };
}