{ config, lib, pkgs, ... }: with lib; let cfg = config.services.dnscrypt-wrapper; dataDir = "/var/lib/dnscrypt-wrapper"; daemonArgs = with cfg; [ "--listen-address=${address}:${toString port}" "--resolver-address=${upstream.address}:${toString upstream.port}" "--provider-name=${providerName}" "--provider-publickey-file=public.key" "--provider-secretkey-file=secret.key" "--provider-cert-file=${providerName}.crt" "--crypt-secretkey-file=${providerName}.key" ]; genKeys = '' # generates time-limited keypairs keyGen() { dnscrypt-wrapper --gen-crypt-keypair \ --crypt-secretkey-file=${cfg.providerName}.key dnscrypt-wrapper --gen-cert-file \ --crypt-secretkey-file=${cfg.providerName}.key \ --provider-cert-file=${cfg.providerName}.crt \ --provider-publickey-file=public.key \ --provider-secretkey-file=secret.key \ --cert-file-expire-days=${toString cfg.keys.expiration} } cd ${dataDir} # generate provider keypair (first run only) if [ ! -f public.key ] || [ ! -f secret.key ]; then dnscrypt-wrapper --gen-provider-keypair fi # generate new keys for rotation if [ ! -f ${cfg.providerName}.key ] || [ ! -f ${cfg.providerName}.crt ]; then keyGen fi ''; rotateKeys = '' # check if keys are not expired keyValid() { fingerprint=$(dnscrypt-wrapper --show-provider-publickey | awk '{print $(NF)}') dnscrypt-proxy --test=${toString (cfg.keys.checkInterval + 1)} \ --resolver-address=127.0.0.1:${toString cfg.port} \ --provider-name=${cfg.providerName} \ --provider-key=$fingerprint } cd ${dataDir} # archive old keys and restart the service if ! keyValid; then echo "certificate soon to become invalid; backing up old cert" mkdir -p oldkeys mv -v ${cfg.providerName}.key oldkeys/${cfg.providerName}-$(date +%F-%T).key mv -v ${cfg.providerName}.crt oldkeys/${cfg.providerName}-$(date +%F-%T).crt systemctl restart dnscrypt-wrapper fi ''; in { ###### interface options.services.dnscrypt-wrapper = { enable = mkEnableOption "DNSCrypt wrapper"; address = mkOption { type = types.str; default = "127.0.0.1"; description = '' The DNSCrypt wrapper will bind to this IP address. ''; }; port = mkOption { type = types.int; default = 5353; description = '' The DNSCrypt wrapper will listen for DNS queries on this port. ''; }; providerName = mkOption { type = types.str; default = "2.dnscrypt-cert.${config.networking.hostName}"; example = "2.dnscrypt-cert.myresolver"; description = '' The name that will be given to this DNSCrypt resolver. Note: the resolver name must start with 2.dnscrypt-cert.. ''; }; upstream.address = mkOption { type = types.str; default = "127.0.0.1"; description = '' The IP address of the upstream DNS server DNSCrypt will "wrap". ''; }; upstream.port = mkOption { type = types.int; default = 53; description = '' The port of the upstream DNS server DNSCrypt will "wrap". ''; }; keys.expiration = mkOption { type = types.int; default = 30; description = '' The duration (in days) of the time-limited secret key. This will be automatically rotated before expiration. ''; }; keys.checkInterval = mkOption { type = types.int; default = 1440; description = '' The time interval (in minutes) between key expiration checks. ''; }; }; ###### implementation config = mkIf cfg.enable { users.users.dnscrypt-wrapper = { description = "dnscrypt-wrapper daemon user"; home = "${dataDir}"; createHome = true; }; users.groups.dnscrypt-wrapper = { }; systemd.services.dnscrypt-wrapper = { description = "dnscrypt-wrapper daemon"; after = [ "network.target" ]; wantedBy = [ "multi-user.target" ]; path = [ pkgs.dnscrypt-wrapper ]; serviceConfig = { User = "dnscrypt-wrapper"; WorkingDirectory = dataDir; Restart = "on-failure"; ExecStart = "${pkgs.dnscrypt-wrapper}/bin/dnscrypt-wrapper ${toString daemonArgs}"; }; preStart = genKeys; }; systemd.services.dnscrypt-wrapper-rotate = { after = [ "network.target" ]; requires = [ "dnscrypt-wrapper.service" ]; description = "Rotates DNSCrypt wrapper keys if soon to expire"; path = with pkgs; [ dnscrypt-wrapper dnscrypt-proxy gawk ]; script = rotateKeys; serviceConfig.User = "dnscrypt-wrapper"; }; systemd.timers.dnscrypt-wrapper-rotate = { description = "Periodically check DNSCrypt wrapper keys for expiration"; wantedBy = [ "multi-user.target" ]; timerConfig = { Unit = "dnscrypt-wrapper-rotate.service"; OnBootSec = "1min"; OnUnitActiveSec = cfg.keys.checkInterval * 60; }; }; }; }