Unverified Commit 069c640f authored by Moraxyc's avatar Moraxyc
Browse files

nixos/getaddrinfo: init 

This commit introduces a new NixOS module `networking.getaddrinfo` to allow
declarative configuration of `/etc/gai.conf`, which controls address
selection behavior for `getaddrinfo(3)` as defined in RFC 3484 and
RFC 6724.
parent 9c09d5e2

nixos/modules/config/getaddrinfo.nix

0 → 100644
+120 −0
Original line number Diff line number Diff line 
{

  pkgs,

  lib,

  config,

  ...

}:

let

  cfg = config.networking.getaddrinfo;



  formatTableEntries =

    tableName: table:

    if table == null then

      [ ]

    else

      lib.mapAttrsToList (cidr: val: "${tableName} ${cidr} ${toString val}") table;



  gaiConfText = lib.concatStringsSep "\n" (

    [

      "# Generated by NixOS module networking.getaddrinfo"

      "# Do not edit manually!"

      "reload ${if cfg.reload then "yes" else "no"}"

    ]

    ++ formatTableEntries "label" cfg.label

    ++ formatTableEntries "precedence" cfg.precedence

    ++ formatTableEntries "scopev4" cfg.scopev4

  );

in

{

  options.networking.getaddrinfo = {

    enable = lib.mkOption {

      type = lib.types.bool;

      default = pkgs.stdenv.hostPlatform.libc == "glibc";

      defaultText = lib.literalExpression ''

        pkgs.stdenv.hostPlatform.libc == "glibc"

      '';

      description = ''

        Enables custom address sorting configuration for {manpage}`getaddrinfo(3)` according to RFC 3484.



        This option generates a {file}`/etc/gai.conf` file to override the default address sorting tables,

        as described in {manpage}`gai.conf(5)`.



        This setting is only applicable when using the GNU C Library (glibc).

        It has no effect with other libc implementations.

      '';

    };



    reload = lib.mkOption {

      type = lib.types.bool;

      default = false;

      description = ''

        Determines whether a process should detect changes to the configuration file since it was last read.



        If enabled, the file is re-read automatically. This may cause issues in multithreaded applications

        and is generally discouraged.

      '';

    };



    label = lib.mkOption {

      type = lib.types.nullOr (lib.types.attrsOf lib.types.int);

      default = null;

      description = ''

        Adds entries to the label table, as described in section 2.1 of RFC 3484.



        If any label entries are provided, the glibc’s default label table is ignored.

      '';

      example = {

        "::/0" = 1;

        "2002::/16" = 2;

        "::/96" = 3;

        "::ffff:0:0/96" = 4;

        "fec0::/10" = 5;

        "fc00::/7" = 6;

        "2001:0::/32" = 7;

      };

    };



    precedence = lib.mkOption {

      type = lib.types.nullOr (lib.types.attrsOf lib.types.int);

      default = null;

      description = ''

        Similar to {option}`networking.getaddrinfo.label`, but this option

        defines entries for the precedence table instead.



        See sections 2.1 and 10.3 of RFC 3484 for details.



        Providing any value will disable the glibc's default precedence table.

      '';

      example = {

        "::1/128" = 50;

        "::/0" = 40;

        "2002::/16" = 30;

        "::/96" = 20;

        "::ffff:0:0/96" = 10;

      };

    };



    scopev4 = lib.mkOption {

      type = lib.types.nullOr (lib.types.attrsOf lib.types.int);

      default = null;

      description = ''

        Adds custom rules to the IPv4 scope table.



        By default, the scope IDs described in section 3.2 of RFC 6724 are used.



        Modifying these values is rarely necessary.

      '';

      example = {

        "::ffff:169.254.0.0/112" = 2;

        "::ffff:127.0.0.0/104" = 2;

        "::ffff:0.0.0.0/96" = 14;

      };

    };

  };



  config = lib.mkIf cfg.enable {

    environment.etc."gai.conf".text = gaiConfText;

  };



  meta.maintainers = with lib.maintainers; [ moraxyc ];

}

nixos/modules/module-list.nix

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
  ./config/fonts/fontdir.nix

  ./config/fonts/ghostscript.nix

  ./config/fonts/packages.nix

  ./config/getaddrinfo.nix

  ./config/gtk/gtk-icon-cache.nix

  ./config/i18n.nix

  ./config/iproute2.nix