Add sipp-sendfax.xml and spandspflow2pcap.py to contrib/scripts.

The spandspflow2pcap.py creates pcap files from fax.log files, generated
through 'fax set debug on' when receiving a fax. An example fax.log is
included as spandspflow2pcap.log.

The sipp-sendfax.xml SIPp scenario can be used to replay that fax with a
recent version of SIPp.

ASTERISK-25660 #close

Change-Id: I4de8f28b084055b482ab8a5b28d28b605b0ed526

contrib/scripts/spandspflow2pcap.py

@@ -0,0 +1,197 @@
+#!/usr/bin/env python
+# vim: set ts=8 sw=4 sts=4 et ai tw=79:
+'''
+Usage: ./spandspflow2pcap.py SPANDSP_LOG SENDFAX_PCAP
+
+Takes a log from Asterisk with SpanDSP, extracts the "received" data
+and puts it in a pcap file. Use 'fax set debug on' and configure
+logger.conf to get fax logs.
+
+Input data should look something like this::
+
+    [2013-08-07 15:17:34] FAX[23479] res_fax.c: FLOW T.38 Rx     5: IFP c0 01 ...
+
+Output data will look like a valid pcap file ;-)
+
+This allows you to reconstruct received faxes into replayable pcaps.
+
+Replaying is expected to be done by SIPp with sipp-sendfax.xml. The
+SIPp binary used for replaying must have image (fax) support. This means
+you'll need a version higher than 3.5.0 (unreleased when writing this),
+or the git master branch: https://github.com/SIPp/sipp
+
+
+Author: Walter Doekes, OSSO B.V. (2013,2015,2016)
+License: Public Domain
+'''
+from base64 import b16decode
+from datetime import datetime, timedelta
+from re import search
+from time import mktime
+from struct import pack
+import sys
+
+
+LOSSY = False
+EMPTY_RECOVERY = False
+
+
+def n2b(text):
+    return b16decode(text.replace(' ', '').replace('\n', '').upper())
+
+
+class FaxPcap(object):
+    PCAP_PREAMBLE = n2b('d4 c3 b2 a1 02 00 04 00'
+                        '00 00 00 00 00 00 00 00'
+                        'ff ff 00 00 71 00 00 00')
+
+    def __init__(self, outfile):
+        self.outfile = outfile
+        self.date = None
+        self.dateoff = timedelta(seconds=0)
+        self.seqno = None
+        self.udpseqno = 128
+        self.prev_data = None
+
+        # Only do this if at pos 0?
+        self.outfile.write(self.PCAP_PREAMBLE)
+
+    def data2packet(self, date, udpseqno, seqno, data, prev_data):
+        sum16 = '\x43\x21'  # checksum is irrelevant for sipp sending
+
+        new_prev = data  # without seqno..
+        data = '%s%s' % (pack('>H', seqno), data)
+        if prev_data:
+            if LOSSY and (seqno % 3) == 2:
+                return '', new_prev
+            if EMPTY_RECOVERY:
+                # struct ast_frame f[16], we have room for a few
+                # packets.
+                packets = 14
+                data += '\x00%c%s%s' % (
+                    chr(packets + 1), '\x00' * packets, prev_data)
+            else:
+                # Add 1 previous packet, without the seqno.
+                data += '\x00\x01' + prev_data
+
+        kwargs = {'udpseqno': pack('>H', udpseqno), 'sum16': sum16}
+
+        kwargs['data'] = data
+        kwargs['lenb16'] = pack('>H', len(kwargs['data']) + 8)
+        udp = '\x00\x01\x00\x02%(lenb16)s%(sum16)s%(data)s' % kwargs
+
+        kwargs['data'] = udp
+        kwargs['lenb16'] = pack('>H', len(kwargs['data']) + 20)
+        ip = ('\x45\xb8%(lenb16)s%(udpseqno)s\x00\x00\xf9\x11%(sum16)s\x01'
+              '\x01\x01\x01\x02\x02\x02\x02%(data)s') % kwargs
+
+        kwargs['data'] = ip
+        frame = ('\x00\x00\x00\x01\x00\x06\x00\x30\x48\xb1\x1c\x34\x00\x00'
+                 '\x08\x00%(data)s') % kwargs
+
+        kwargs['data'] = frame
+        sec = mktime(date.timetuple())
+        msec = date.microsecond
+        datalen = len(kwargs['data'])
+        kwargs['pre'] = pack('<IIII', sec, msec, datalen, datalen)
+        packet = '%(pre)s%(data)s' % kwargs
+
+        return (packet, new_prev)
+
+    def add(self, date, seqno, data):
+        if self.seqno is None:
+            self.seqno = 0
+            for i in range(seqno):
+                # In case the first zeroes were dropped, add them.
+                self.add(date, i, '\x00')
+        assert seqno == self.seqno, '%s != %s' % (seqno, self.seqno)
+
+        # Data is prepended by len(data).
+        data = chr(len(data)) + data
+
+        # Auto-increasing dates
+        if self.date is None or date > self.date:
+            # print 'date is larger', date, self.date
+            self.date = date
+        elif (date < self.date.replace(microsecond=0)):
+            assert False, ('We increased too fast.. decrease delta: %r/%r' %
+                           (date, self.date))
+        else:
+            self.date += timedelta(microseconds=9000)
+
+        print seqno, '\t', self.date + self.dateoff
+
+        # Make packet.
+        packet, prev_data = self.data2packet(self.date + self.dateoff,
+                                             self.udpseqno, self.seqno,
+                                             data, self.prev_data)
+        self.outfile.write(packet)
+
+        # Increase values.
+        self.udpseqno += 1
+        self.seqno += 1
+        self.prev_data = prev_data
+
+    def add_garbage(self, date):
+        if self.date is None or date > self.date:
+            self.date = date
+
+        packet, ignored = self.data2packet(self.date, self.udpseqno,
+                                           0xffff, 'GARBAGE', '')
+        self.udpseqno += 1
+
+        self.outfile.write(packet)
+
+
+with open(sys.argv[1], 'r') as infile:
+    with open(sys.argv[2], 'wb') as outfile:
+        first = True
+        p = FaxPcap(outfile)
+        # p.add(datetime.now(), 0, n2b('06'))
+        # p.add(datetime.now(), 1, n2b('c0 01 80 00 00 ff'))
+
+        for lineno, line in enumerate(infile):
+            # Look for lines like:
+            # [2013-08-07 15:17:34] FAX[23479] res_fax.c: \
+            #   FLOW T.38 Rx     5: IFP c0 01 80 00 00 ff
+            if 'FLOW T.38 Rx' not in line:
+                continue
+            if 'IFP' not in line:
+                continue
+
+            match = search(r'(\d{4})-(\d\d)-(\d\d) (\d\d):(\d\d):(\d\d)', line)
+            assert match
+            date = datetime(*[int(i) for i in match.groups()])
+
+            match = search(r'Rx\s*(\d+):', line)
+            assert match
+            seqno = int(match.groups()[0])
+
+            match = search(r': IFP ([0-9a-f ]+)', line)
+            assert match
+            data = n2b(match.groups()[0])
+
+            # Have the file start a second early.
+            if first:
+                p.add_garbage(date)
+                first = False
+
+            # Add the packets.
+            #
+            # T.38 basic format of UDPTL payload section with redundancy:
+            #
+            # UDPTL_SEQNO
+            # - 2 sequence number (big endian)
+            # UDPTL_PRIMARY_PAYLOAD (T30?)
+            # - 1 subpacket length (excluding this byte)
+            # - 1 type of message (e.g. 0xd0 for data(?))
+            # - 1 items in data field (e.g. 0x01)
+            # - 2 length of data (big endian)
+            # - N data
+            # RECOVERY (optional)
+            # - 2 count of previous seqno packets (big endian)
+            # - N UDPTL_PRIMARY_PAYLOAD of (seqno-1)
+            # - N UDPTL_PRIMARY_PAYLOAD of (seqno-2)
+            # - ...
+            #
+            p.add(date, seqno, data)