nixos/pulseaudio: tcp streaming & zeroconf

Adds options for tcp streaming and avahi zeroconf support (so that the
server can be easily found by clients).
There is also an option to allow anonymous clients to stream to the
server (by default pulseaudio uses a cookie mechanism, see manpage).

nixos/modules/config/pulseaudio.nix

@@ -9,11 +9,36 @@ let
 
   systemWide = cfg.enable && cfg.systemWide;
   nonSystemWide = cfg.enable && !cfg.systemWide;
+  hasZeroconf = let z = cfg.zeroconf; in z.publish.enable || z.discovery.enable;
+
+  overriddenPackage = cfg.package.override
+    (optionalAttrs hasZeroconf { zeroconfSupport = true; });
+  binary = "${getBin overriddenPackage}/bin/pulseaudio";
+  binaryNoDaemon = "${binary} --daemonize=no";
 
   # Forces 32bit pulseaudio and alsaPlugins to be built/supported for apps
   # using 32bit alsa on 64bit linux.
   enable32BitAlsaPlugins = cfg.support32Bit && stdenv.isx86_64 && (pkgs_i686.alsaLib != null && pkgs_i686.libpulseaudio != null);
 
+
+  myConfigFile =
+    let
+      addModuleIf = cond: mod: optionalString cond "load-module ${mod}";
+      allAnon = optional cfg.tcp.anonymousClients.allowAll "auth-anonymous=1";
+      ipAnon =  let a = cfg.tcp.anonymousClients.allowedIpRanges;
+                in optional (a != []) ''auth-ip-acl=${concatStringsSep ";" a}'';
+    in writeTextFile {
+      name = "default.pa";
+        text = ''
+        .include ${cfg.configFile}
+        ${addModuleIf cfg.zeroconf.publish.enable "module-zeroconf-publish"}
+        ${addModuleIf cfg.zeroconf.discovery.enable "module-zeroconf-discover"}
+        ${addModuleIf cfg.tcp.enable (concatStringsSep " "
+           ([ "load-module module-native-protocol-tcp" ] ++ allAnon ++ ipAnon))}
+        ${cfg.extraConfig}
+      '';
+    };
+
   ids = config.ids;
 
   uid = ids.uids.pulseaudio;
@@ -26,7 +51,7 @@ let
   # are built with PulseAudio support (like KDE).
   clientConf = writeText "client.conf" ''
     autospawn=${if nonSystemWide then "yes" else "no"}
-    ${optionalString nonSystemWide "daemon-binary=${cfg.package.out}/bin/pulseaudio"}
+    ${optionalString nonSystemWide "daemon-binary=${binary}"}
     ${cfg.extraClientConf}
   '';
 
@@ -44,7 +69,7 @@ let
       hint.description "Default Audio Device (via PulseAudio)"
     }
     ctl_type.pulse {
-      libs.native = ${alsaPlugins}/lib/alsa-lib/libasound_module_ctl_pulse.so ;
+      libs.native = ${pkgs.alsaPlugins}/lib/alsa-lib/libasound_module_ctl_pulse.so ;
       ${lib.optionalString enable32BitAlsaPlugins
      "libs.32Bit = ${pkgs_i686.alsaPlugins}/lib/alsa-lib/libasound_module_ctl_pulse.so ;"}
     }
@@ -89,16 +114,25 @@ in {
       };
 
       configFile = mkOption {
-        type = types.path;
+        type = types.nullOr types.path;
         description = ''
-          The path to the configuration the PulseAudio server
+          The path to the default configuration options the PulseAudio server
           should use. By default, the "default.pa" configuration
           from the PulseAudio distribution is used.
         '';
       };
 
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        description = ''
+          Literal string to append to <literal>configFile</literal>
+          and the config file generated by the pulseaudio module.
+        '';
+      };
+
       extraClientConf = mkOption {
-        type = types.str;
+        type = types.lines;
         default = "";
         description = ''
           Extra configuration appended to pulse/client.conf file.
@@ -127,6 +161,31 @@ in {
           '';
         };
       };
+
+      zeroconf = {
+        discovery.enable =
+          mkEnableOption "discovery of pulseaudio sinks in the local network";
+        publish.enable =
+          mkEnableOption "publishing the pulseaudio sink in the local network";
+      };
+
+      # TODO: enable by default?
+      tcp = {
+        enable = mkEnableOption "tcp streaming support";
+
+        anonymousClients = {
+          allowAll = mkEnableOption "all anonymous clients to stream to the server";
+          allowedIpRanges = mkOption {
+            type = types.listOf types.str;
+            default = [];
+            example = literalExample ''[ "127.0.0.1" "192.168.1.0/24" ]'';
+            description = ''
+              A list of IP subnets that are allowed to stream to the server.
+            '';
+          };
+        };
+      };
+
     };
 
   };
@@ -139,11 +198,11 @@ in {
         source = clientConf;
       };
 
-      hardware.pulseaudio.configFile = mkDefault "${getBin cfg.package}/etc/pulse/default.pa";
+      hardware.pulseaudio.configFile = mkDefault "${getBin overriddenPackage}/etc/pulse/default.pa";
     }
 
     (mkIf cfg.enable {
-      environment.systemPackages = [ cfg.package ];
+      environment.systemPackages = [ overriddenPackage ];
 
       environment.etc = singleton {
         target = "asound.conf";
@@ -152,12 +211,21 @@ in {
 
       # Allow PulseAudio to get realtime priority using rtkit.
       security.rtkit.enable = true;
+
+    })
+
+    (mkIf hasZeroconf {
+      services.avahi.enable = true;
+    })
+    (mkIf cfg.zeroconf.publish.enable {
+      services.avahi.publish.enable = true;
+      services.avahi.publish.userServices = true;
     })
 
     (mkIf nonSystemWide {
       environment.etc = singleton {
         target = "pulse/default.pa";
-        source = cfg.configFile;
+        source = myConfigFile;
       };
 
       systemd.user = {
@@ -167,10 +235,11 @@ in {
           wantedBy = [ "default.target" ];
           serviceConfig = {
             Type = "notify";
-            ExecStart = "${getBin cfg.package}/bin/pulseaudio --daemonize=no";
+            ExecStart = binaryNoDaemon;
             Restart = "on-failure";
           };
           environment = { DISPLAY = ":${toString config.services.xserver.display}"; };
+          restartIfChanged = true;
         };
 
         sockets.pulseaudio = {
@@ -205,7 +274,7 @@ in {
         environment.PULSE_RUNTIME_PATH = stateDir;
         serviceConfig = {
           Type = "notify";
-          ExecStart = "${getBin cfg.package}/bin/pulseaudio --daemonize=no --log-level=${cfg.daemon.logLevel} --system -n --file=${cfg.configFile}";
+          ExecStart = "${binaryNoDaemon} --log-level=${cfg.daemon.logLevel} --system -n --file=${myConfigFile}";
           Restart = "on-failure";
         };
       };