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-rw-r--r--openbsc/contrib/nat/ussd_example.py65
1 files changed, 65 insertions, 0 deletions
diff --git a/openbsc/contrib/nat/ussd_example.py b/openbsc/contrib/nat/ussd_example.py
new file mode 100644
index 000000000..8f7a58d3f
--- /dev/null
+++ b/openbsc/contrib/nat/ussd_example.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python2.7
+
+"""
+AGPLv3+ 2016 Copyright Holger Hans Peter Freyther
+
+Example of how to connect to the USSD side-channel and how to respond
+with a fixed message.
+"""
+
+import socket
+import struct
+
+ussdSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+ussdSocket.connect(('127.0.0.1', 5001))
+
+def send_dt1(dstref, data):
+ dlen = struct.pack('B', len(data)).encode('hex')
+ hex = '06' + dstref.encode('hex') + '00' + '01' + dlen + data.encode('hex')
+ pdata = hex.decode('hex')
+ out = struct.pack('>HB', len(pdata), 0xfd) + pdata
+ ussdSocket.send(out)
+
+def send_rel(srcref, dstref):
+ hex = '04' + dstref.encode('hex') + srcref.encode('hex') + '000100'
+ pdata = hex.decode('hex')
+ out = struct.pack('>HB', len(pdata), 0xfd) + pdata
+ ussdSocket.send(out)
+
+def recv_one():
+ plen = ussdSocket.recv(3)
+ (plen,ptype) = struct.unpack(">HB", plen)
+ data = ussdSocket.recv(plen)
+
+ return ptype, data
+
+# Assume this is the ID request
+data = ussdSocket.recv(4)
+ussdSocket.send("\x00\x08\xfe\x05\x00" + "\x05\x01" + "ussd")
+# ^len ^len of tag ... and ignore
+
+# Expect a fake message. see struct ipac_msgt_sccp_state
+ptype, data = recv_one()
+print("%d %s" % (ptype, data.encode('hex')))
+(srcref, dstref, transid, invokeid) = struct.unpack("<3s3sBB", data[1:9])
+print("New transID %d invoke %d" % (transid, invokeid))
+
+# Expect a the invocation.. todo.. extract invoke id
+ptype, data = recv_one()
+print("%d %s" % (ptype, data.encode('hex')))
+
+# Reply with BSSAP + GSM 04.08 + MAP portion
+# 00 == invoke id 0f == DCS
+res = "01002a9b2a0802e1901c22a220020100301b02013b301604010f041155e7d2f9bc3a41412894991c06a9c9a713"
+send_dt1(dstref, res.decode('hex'))
+
+clear = "000420040109"
+send_dt1(dstref, clear.decode('hex'))
+
+# should be the clear complete
+send_rel(srcref, dstref)
+
+# Give it some time to handle connection shutdown properly
+print("Gracefully sleeping")
+import time
+time.sleep(3)