From 798b6b6a6562e2174e1b22279526be2a34a5d5de Mon Sep 17 00:00:00 2001
From: Michael Bailey <strictlymike@gmail.com>
Date: Tue, 15 Aug 2017 13:37:21 -0700
Subject: [PATCH] Banner generation (and date/time evaluation) upon use

---
 fakenet/listeners/BannerFactory.py | 41 +++++++++++++++++++++++++++---
 fakenet/listeners/FTPListener.py   |  4 +--
 fakenet/listeners/IRCListener.py   |  7 ++---
 3 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/fakenet/listeners/BannerFactory.py b/fakenet/listeners/BannerFactory.py
index 279cc26..34d6f7b 100644
--- a/fakenet/listeners/BannerFactory.py
+++ b/fakenet/listeners/BannerFactory.py
@@ -3,6 +3,38 @@
 import string
 import datetime
 
+class Banner():
+    """Act like a string, but actually get date/time components on the fly."""
+
+    def __init__(self, banner, insertions):
+        self.banner = banner
+        self.insertions = insertions
+        # Indicate an error in the banner early-on as opposed to
+        # when a login or other event occurs.
+        test = self.failEarly()
+
+    def failEarly(self):
+        """Raise exceptions upon construction rather than later."""
+        return self.fmt()
+
+    def __len__(self):
+        """Needed for pyftpdlib.
+        
+        If the length changes between the time when the caller obtains the
+        length and the time when they reference the string, then... *shrug*?
+        """
+        return len(self.fmt())
+
+    def __repr__(self):
+        return self.fmt()
+
+    def fmt(self):
+        banner = self.banner
+        banner = datetime.datetime.now().strftime(banner)
+        banner = banner % self.insertions
+        banner = banner.replace('\\n', '\n').replace('\\t', '\t')
+        return banner
+
 class BannerFactory():
     def genBanner(self, config, bannerdict, defaultbannerkey='!generic'):
         """Select and format a banner.
@@ -55,11 +87,12 @@ def genBanner(self, config, bannerdict, defaultbannerkey='!generic'):
 
         insertions = {'servername': servername, 'tz': 'UTC'}
 
-        banner = datetime.datetime.now().strftime(banner)
-        banner = banner % insertions
-        banner = banner.replace('\\n', '\n').replace('\\t', '\t')
+        return Banner(banner, insertions)
 
-        return banner
+        # banner = datetime.datetime.now().strftime(banner)
+        # banner = banner % insertions
+        # banner = banner.replace('\\n', '\n').replace('\\t', '\t')
+        # return banner
 
     def randomizeHostname(self):
         valid_hostname_charset = (string.ascii_letters + string.digits + '-')
diff --git a/fakenet/listeners/FTPListener.py b/fakenet/listeners/FTPListener.py
index a177abc..334ec3c 100644
--- a/fakenet/listeners/FTPListener.py
+++ b/fakenet/listeners/FTPListener.py
@@ -255,7 +255,7 @@ def start(self):
         else:
             self.handler = FakeFTPHandler
 
-        self.handler.banner = self.banner()
+        self.handler.banner = self.genBanner()
 
         self.handler.ftproot_path = self.ftproot_path
         self.handler.abstracted_fs = FakeFS
@@ -279,7 +279,7 @@ def stop(self):
         if self.server:
             self.server.close_all()
 
-    def banner(self):
+    def genBanner(self):
         bannerfactory = BannerFactory.BannerFactory()
         return bannerfactory.genBanner(self.config, BANNERS)
 
diff --git a/fakenet/listeners/IRCListener.py b/fakenet/listeners/IRCListener.py
index 96d2860..35b61d4 100644
--- a/fakenet/listeners/IRCListener.py
+++ b/fakenet/listeners/IRCListener.py
@@ -15,7 +15,7 @@
 SRV_WELCOME = "Welcome to FakeNet."
 
 BANNERS = {
-    'generic': 'Welcome to IRC - %%(servername)s - %a %b %d %H:%M:%S %%(tz)s %Y',
+    'generic': 'Welcome to IRC - %(servername)s - %a %b %d %H:%M:%S %(tz)s %Y',
     'debian-ircd-irc2': (
         '17/10/2011 11:50\n' +
         '                         [ Debian GNU/Linux ]\n' +
@@ -49,6 +49,7 @@ def start(self):
 
         self.server = ThreadedTCPServer((self.local_ip, int(self.config['port'])), ThreadedTCPRequestHandler)
 
+        self.banner = self.genBanner()
         self.server.listener = self
         self.server.logger = self.logger
         self.server.config = self.config
@@ -64,7 +65,7 @@ def stop(self):
             self.server.shutdown()
             self.server.server_close()
 
-    def banner(self):
+    def genBanner(self):
         bannerfactory = BannerFactory.BannerFactory()
         return bannerfactory.genBanner(self.config, BANNERS)
 
@@ -117,7 +118,7 @@ def irc_NICK(self, cmd, params):
 
         self.nick = params
 
-        banner = self.server.listener.banner()
+        banner = self.server.listener.banner
 
         self.irc_send_server("001", "%s :%s" % (self.nick, banner))
         self.irc_send_server("376", "%s :End of /MOTD command." % self.nick)