Add tarpit plugin

config/tarpit.timeout

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+0

docs/plugins/tarpit.md

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+tarpit
+======
+
+This plugin is designed to introduce deliberate delays on the response 
+of every hook in order to slow down a connection.  It has no 
+configuration and is designed to be used only by other plugins.
+
+It must be loaded early in config/plugins (e.g. before any plugins 
+that accept recipients or that return OK) but must be loaded *after* 
+any plugins that wish to use it.
+
+To use this plugin in another plugin set:
+
+    connection.notes.tarpit = <seconds to delay>;
+
+or
+
+    connection.transaction.notes.tarpit = <seconds to delay>;
+
+When tarpitting a command it will log 'tarpitting response for Ns' to 
+the INFO facility where N is the number of seconds.

plugins/tarpit.js

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+// tarpit
+
+exports.register = function () {
+    // Register tarpit function last
+    var self = this;
+    ['connect', 'helo', 'ehlo', 'mail', 'rcpt', 'rcpt_ok', 'data',
+     'data_post', 'queue', 'unrecognized_command', 'vrfy', 'noop', 
+     'rset', 'quit'].forEach(function (hook) {
+        self.register_hook(hook, 'tarpit');
+    });
+}
+
+exports.tarpit = function (next, connection) {
+    var transaction = connection.transaction;
+    var conn_delay, trans_delay;
+    if (transaction && transaction.notes) {
+        trans_delay = transaction.notes.tarpit;
+    }
+    if (connection && connection.notes) {
+        conn_delay = connection.notes.tarpit;
+    }
+    var delay = trans_delay || conn_delay;
+    if (delay) {
+        connection.loginfo(this, 'tarpitting response for ' + delay + 's');
+        setTimeout(function () {
+            // Only return if we still have a connection...
+            if (connection) return next();
+        }, (delay*1000));
+    }
+    else {
+        return next();
+    }
+}