From 9404ac3e30976106a73336ccbc6bf97142030c42 Mon Sep 17 00:00:00 2001
From: Daniel Lenski <dlenski@gmail.com>
Date: Sun, 13 Dec 2020 09:45:21 -0800
Subject: [PATCH] tncc-emulate.py: add TNCC_USER_AGENT override variable

See https://gitlab.com/openconnect/openconnect/-/issues/207#note_465454559 for use case and discussion

Signed-off-by: Daniel Lenski <dlenski@gmail.com>
---
 trojans/tncc-emulate.py | 15 +++++++++++----
 www/tncc.xml            |  7 +++++--
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/trojans/tncc-emulate.py b/trojans/tncc-emulate.py
index 559a5186..6b376a66 100755
--- a/trojans/tncc-emulate.py
+++ b/trojans/tncc-emulate.py
@@ -33,9 +33,14 @@
 # https://github.com/russdill/juniper-vpn-py/blame/master/README.host_checker):
 #
 # TNCC_DEVICE_ID: May need to be overriden to match a known value from a computer
-#   running the official Windows client software (obtained from the registry key
+#   running the official client software (on Windows, obtained from the registry key
 #   \HKEY_CURRENT_USER\Software\Juniper Networks\Device Id)
 #
+# TNCC_USER_AGENT: May need to be overriden to match a known value from a computer
+#   running the official Windows client software. For historical reasons, the default
+#   value is 'Neoteris NC Http'; the value 'DSClient; PulseLinux' is known to be sent
+#   by the official Pulse Linux client.
+#
 # TNCC_FUNK: Set TNCC_FUNK=1 to force the use of client machine identification
 #   (known as "funk" to Juniper). This identification will include host platform,
 #   a list of network hardware/MAC addresses, and client certificates requested
@@ -270,7 +275,7 @@ def __init__(self, cert_file):
         self.subject = self.decode_names(tbs['subject'])
 
 class tncc(object):
-    def __init__(self, vpn_host, device_id=None, funk=None, platform=None, hostname=None, mac_addrs=[], certs=[], interval=None):
+    def __init__(self, vpn_host, device_id=None, funk=None, platform=None, hostname=None, mac_addrs=[], certs=[], interval=None, user_agent=None):
         self.vpn_host = vpn_host
         self.path = '/dana-na/'
 
@@ -304,7 +309,7 @@ def __init__(self, vpn_host, device_id=None, funk=None, platform=None, hostname=
             self.br.set_debug_redirects(True)
             self.br.set_debug_responses(True)
 
-        self.user_agent = 'Neoteris HC Http'
+        self.user_agent = user_agent
         self.br.addheaders = [('User-agent', self.user_agent)]
 
     def find_cookie(self, name):
@@ -636,6 +641,8 @@ def do_handshake(self, *args, **kw):
 
     platform = os.environ.get('TNCC_PLATFORM', platform.system() + ' ' + platform.release())
 
+    user_agent = os.environ.get('TNCC_USER_AGENT', 'Neoteris HC Http')
+
     if 'TNCC_HWADDR' in os.environ:
         mac_addrs = [n.strip() for n in os.environ['TNCC_HWADDR'].split(',')]
     else:
@@ -685,7 +692,7 @@ def do_handshake(self, *args, **kw):
     # \HKEY_CURRENT_USER\Software\Juniper Networks\Device Id
     device_id = os.environ.get('TNCC_DEVICE_ID')
 
-    t = tncc(vpn_host, device_id, funk, platform, hostname, mac_addrs, certs, interval)
+    t = tncc(vpn_host, device_id, funk, platform, hostname, mac_addrs, certs, interval, user_agent)
     sock = socket.fromfd(0, socket.AF_UNIX, socket.SOCK_SEQPACKET)
     server = tncc_server(sock, t)
     while True:
diff --git a/www/tncc.xml b/www/tncc.xml
index f1d65719..c6402903 100644
--- a/www/tncc.xml
+++ b/www/tncc.xml
@@ -50,8 +50,11 @@ the <tt>trojans/</tt> subdirectory:</p>
   <li><p><tt>tncc-emulate.py</tt>: This Python 3.x script does <b>not</b> actually run the <tt>tncc.jar</tt> binary.
   Instead, it <i>emulates</i> the behaviour of the <tt>tncc.jar</tt> binary, rather than actually
   executing it. Because this script does not actually execute a server-provided binary, security concerns are greatly
-  alleviated. However, it may require customization to work with VPNs that have modified
-  the behaviour of their Host Checker binaries in some way; consult its source code for details.</p>
+  alleviated.</p>
+
+  <p>It may require configuration or customization to work with VPNs that have modified
+  the behaviour of their Host Checker binaries in some way; consult its source code for details, starting with the
+  list of environment variables that may be set to overriden some of the data that it sends to the server.</p>
 
   <p>This script is based entirely on <a href="https://github.com/russdill/juniper-vpn-py"><tt>tncc.py</tt>
   from russdill/juniper-vpn-py on GitHub</a>.)</p></li>