# HG changeset patch
# User Michael Schloh von Bennewitz <michael@schloh.com>
# Date 1407956415 -7200
# Node ID 42e83b3431d98cabb18107f3ecaaedc5a8c1e110
# Parent  eff35b87fb5637e0aa73bfc7708fa87b3d07e74e
Include signal handler and complete most of service daemon logic.

diff -r eff35b87fb56 -r 42e83b3431d9 src/app.js
--- a/src/app.js	Wed Aug 13 20:56:48 2014 +0200
+++ b/src/app.js	Wed Aug 13 21:00:15 2014 +0200
@@ -45,6 +45,16 @@
 var nameinst = require('native-dns');
 
 
+// install POSIX signal handlers
+process.on('SIGUSR2', function() {
+  console.log('SIGUSR2: Dumping mDNSGw entries at', Date());
+  rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});
+});
+process.on('SIGHUP', function() {
+  console.log('SIGHUP: Cleared all database entries at', Date());
+  cleardb();
+});
+
 // instantiate a new redis client
 // http://www.rediscookbook.org/
 var rediscli = redisdat.createClient();
@@ -53,17 +63,20 @@
 });
 
 // clear mDNS service keys
-rediscli.del('hostnames');
-// this is not working unfortunately for the loop
-rediscli.keys('*', function (error, replies) {
-  replies.forEach(function (reply, ident) {
-    rediscli.del(reply, function (error, value) {
-      if (error) throw(error);
+function cleardb () {
+  rediscli.del('hostnames');
+  // this is not working unfortunately for the loop
+  rediscli.keys('*', function (error, replies) {
+    replies.forEach(function (reply, ident) {
+      rediscli.del(reply, function (error, value) {
+        if (error) throw(error);
+      });
     });
   });
-});
+}
 
 // scan all advertised mDNS service types
+cleardb(); // clear old data first
 var browsall = mdnsinst.browseThemAll();
 browsall.on('serviceUp', function(service) {
     // iterate through hosts and watch accordingly
@@ -88,9 +101,13 @@
         rediscli.hset('hostnames', service.host.replace(/\.$/, ''), service.addresses);
       });
       browserv.on('serviceDown', function(service) {
-        //console.log('service down: ', service);
+        console.log('service down: ', service);
         //FIXME: still need to selectively remove hosts
       });
+      browserv.on('serviceChanged', function(service) {
+        console.log('service changed: ', service);
+        //FIXME: still need to selectively update hosts
+      });
       browserv.start();
     }
 });
@@ -147,7 +164,36 @@
   console.log('DNS problem: ', err.stack);
 });
 
-nameserv.serve(15353);
+//// debug process user
+//console.log('Start.');
+//console.log(process.env.USER);
+//console.log(process.env.SUDO_USER);
+//console.log('Done.');
+//
+// <1024 must run privileged
+var nudpport = 53; // default DNS
+if (nudpport < 1024 && process.getuid() !== 0) {
+  //console.log('Serving on port <1024 from an unprivileged user.\nChange to root if using a privileged port number.')
+  throw new Error('Serving on port <1024 from an unprivileged user.')
+}
+
+// start the DNS process
+nameserv.serve(nudpport, function () {
+  try {
+    console.log('Starting mDNSGw on', Date());
+    process.stdout.write('Old UID: ' + process.getuid() + ', Old GID: ' + process.getgid() + '... ');
+    process.umask('0644');
+    process.setgid('daemon');
+    if (process.env.SUDO_USER)
+      process.setuid(process.env.SUDO_USER);
+    else
+      process.setuid('daemon');
+    console.log('New UID: ' + process.getuid() + ', New GID: ' + process.getgid());
+  } catch (err) {
+    console.log('Cowardly refusing to keep the process alive as root.');
+    process.exit(1);
+  }
+});
 
 //// debug print all key and value database entries
 //rediscli.hgetall('hostnames', function (error, object) {console.dir(object);});