Add DOCSIS/Cable Modem Discovery (#646)

* Add DOCSIS/Cable Modem Discovery

lib/App/Netdisco/Worker/Plugin/Discover/Neighbors/DOCSIS.pm

@@ -0,0 +1,48 @@
+package App::Netdisco::Worker::Plugin::Discover::Neighbors::DOCSIS;
+use Dancer ':syntax';
+
+use App::Netdisco::Worker::Plugin;
+use App::Netdisco::Transport::SNMP;
+use aliased 'App::Netdisco::Worker::Status';
+
+use App::Netdisco::Util::Device qw/get_device is_discoverable/;
+use App::Netdisco::JobQueue 'jq_insert';
+
+register_worker({ phase => 'main', driver => 'snmp' }, sub {
+  my ($job, $workerconf) = @_;
+
+  my $device = $job->device;
+  return unless $device->in_storage;
+  my $snmp = App::Netdisco::Transport::SNMP->reader_for($device)
+    or return Status->defer("discover failed: could not SNMP connect to $device");
+
+  my $modems = $snmp->docs_if_cmts_cm_status_inet_address() || {};
+
+  return Status->info(" [$device] neigh - no modems (probably not a DOCSIS device)")
+    unless (scalar values %$modems);
+
+  my $count = 0;
+  foreach my $ip (values %$modems) { 
+
+    # Some modems may be registered, but not have an IP assigned (they could be offline, disabled, etc)
+    next if $ip eq '';
+
+    my $peer = get_device($ip);
+    next if $peer->in_storage or not is_discoverable($peer);
+    next if vars->{'queued'}->{$ip};
+
+    jq_insert({
+      device => $ip,
+      action => 'discover',
+      subaction => 'with-nodes',
+    });
+
+    $count++;
+    vars->{'queued'}->{$ip} += 1;
+    debug sprintf ' [%s] queue - queued %s for discovery (DOCSIS peer)', $device, $ip;
+  }
+
+  return Status->info(" [$device] neigh - $count DOCSIS peers (modems) added to queue.");
+});
+
+true;