contrib/scripts: Make spandspflow2pcap.py Python 2.7+/3.3+ compatible

Change-Id: Ica182a891743017ff3cda16de3d95335fffd9a91

contrib/scripts/spandspflow2pcap.py

@@ -9,7 +9,7 @@ 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 ...
+    [2013-08-07 15:17:34] FAX[23479] res_fax.c: FLOW T.38 Rx     5: IFP c0 ...
 
 Output data will look like a valid pcap file ;-)
 
@@ -21,14 +21,16 @@ 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)
+Author: Walter Doekes, OSSO B.V. (2013,2015,2016,2019)
 License: Public Domain
 '''
 from base64 import b16decode
+from collections import namedtuple
 from datetime import datetime, timedelta
 from re import search
 from time import mktime
 from struct import pack
+import os
 import sys
 
 
@@ -36,124 +38,176 @@ LOSSY = False
 EMPTY_RECOVERY = False
 
 
+IFP = namedtuple('IFP', 'date seqno data')  # datetime, int, bytearray
+
+
 def n2b(text):
-    return b16decode(text.replace(' ', '').replace('\n', '').upper())
+    """
+    Convert "aa bb cc" to bytearray('\xaa\xbb\xcc').
+    """
+    return bytearray(
+        b16decode(text.replace(' ', '').replace('\n', '').upper()))
+
+
+class SkipPacket(Exception):
+    pass
 
 
 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')
+    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}
+    def add(self, ifp):
+        """
+        Add the IFP packet.
+
+        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)
+        - ...
+        """
+        # First packet?
+        if self.seqno is None:
+            # Add preamble.
+            self._add_preamble()
+            # Start a second late (optional).
+            self._add_garbage(ifp.date)
 
-        kwargs['data'] = data
-        kwargs['lenb16'] = pack('>H', len(kwargs['data']) + 8)
-        udp = '\x00\x01\x00\x02%(lenb16)s%(sum16)s%(data)s' % kwargs
+            # Set sequence, and fill with missing leading zeroes.
+            self.seqno = 0
+            for i in range(ifp.seqno):
+                self.add(IFP(date=ifp.date, seqno=i, data=bytearray([0])))
 
-        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
+        # Auto-increasing dates
+        if self.date is None or ifp.date > self.date:
+            self.date = ifp.date
+        elif ifp.date < self.date.replace(microsecond=0):
+            assert False, 'More packets than expected in 1s? {!r}/{!r}'.format(
+                ifp.date, self.date)
+        else:
+            self.date += timedelta(microseconds=9000)
 
-        kwargs['data'] = ip
-        frame = ('\x00\x00\x00\x01\x00\x06\x00\x30\x48\xb1\x1c\x34\x00\x00'
-                 '\x08\x00%(data)s') % kwargs
+        # Add packet.
+        self.seqno = ifp.seqno
+        try:
+            self.outfile.write(self._make_packet(ifp.data))
+        except SkipPacket:
+            pass
 
-        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
+    def _add_preamble(self):
+        self.outfile.write(self.PCAP_PREAMBLE)
 
-        return (packet, new_prev)
+    def _add_garbage(self, date):
+        if self.date is None or date > self.date:
+            self.date = date
 
-    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)
+        self.seqno = 0xffff
+        self.outfile.write(self._make_packet(
+            bytearray(b'GARBAGE'), is_ifp=False))
 
-        # Data is prepended by len(data).
-        data = chr(len(data)) + data
+    def _make_packet(self, ifp_data, is_ifp=True):
+        sum16 = bytearray(b'\x43\x21')  # the OS fixes the checksums for us
 
-        # 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))
+        data = bytearray()
+        if is_ifp:
+            data.append(len(ifp_data))  # length
+            data.extend(ifp_data)       # data
+            self.prev_data, prev_data = data[:], self.prev_data
         else:
-            self.date += timedelta(microseconds=9000)
+            data.extend(ifp_data)
+            prev_data = None
 
-        print(seqno, '\t', self.date + self.dateoff)
+        if prev_data:
+            if LOSSY and (self.seqno % 3) == 2:
+                self.udpseqno += 1
+                raise SkipPacket()
 
-        # Make packet.
-        packet, prev_data = self.data2packet(self.date + self.dateoff,
-                                             self.udpseqno, self.seqno,
-                                             data, self.prev_data)
-        self.outfile.write(packet)
+            if EMPTY_RECOVERY:
+                # struct ast_frame f[16], we have room for a few
+                # packets.
+                packets = 14
+                data.extend([0, packets + 1] + [0] * packets)
+                data.extend(prev_data)
+            else:
+                # Add 1 previous packet, without the seqno.
+                data.extend([0, 1])
+                data.extend(prev_data)
+
+        # Wrap it in UDP
+        udp = bytearray(
+            b'\x00\x01\x00\x02%(len)s%(sum16)s%(seqno)s%(data)s' % {
+                b'len': pack('>H', len(data) + 10),
+                b'sum16': sum16,
+                b'seqno': pack('>H', self.seqno),
+                b'data': data})
+
+        # Wrap it in IP
+        ip = bytearray(
+            b'\x45\xb8%(len)s%(udpseqno)s\x00\x00\xf9\x11%(sum16)s'
+            b'\x01\x01\x01\x01\x02\x02\x02\x02%(udp)s' % {
+                b'len': pack('>H', len(udp) + 20),
+                b'udpseqno': pack('>H', self.udpseqno),
+                b'sum16': sum16,
+                b'udp': udp})
+
+        # Wrap it in Ethernet
+        ethernet = bytearray(
+            b'\x00\x00\x00\x01\x00\x06\x00\x30\x48\xb1\x1c\x34\x00\x00'
+            b'\x08\x00%(ip)s' % {b'ip': ip})
+
+        # Wrap it in a pcap packet
+        packet = bytearray(b'%(prelude)s%(ethernet)s' % {
+            b'prelude': pack(
+                '<IIII', int(mktime(self.date.timetuple())),
+                self.date.microsecond, len(ethernet), len(ethernet)),
+            b'ethernet': ethernet})
 
         # 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
+        return packet
 
-        packet, ignored = self.data2packet(self.date, self.udpseqno,
-                                           0xffff, 'GARBAGE', '')
-        self.udpseqno += 1
 
-        self.outfile.write(packet)
+class SpandspLog:
+    def __init__(self, fp):
+        self._fp = fp
+
+    def __iter__(self):
+        r"""
+        Looks for lines line:
 
+            [2013-08-07 15:17:34] FAX[23479] res_fax.c: \
+              FLOW T.38 Rx     5: IFP c0 01 80 00 00 ff
 
-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'))
+        And yields:
 
-        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
+            IFP(date=..., seqno=..., data=...)
+        """
+        prev_seqno = None
+
+        for lineno, line in enumerate(self._fp):
             if 'FLOW T.38 Rx' not in line:
                 continue
             if 'IFP' not in line:
@@ -171,27 +225,37 @@ with open(sys.argv[1], 'r') as infile:
             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)
+            if prev_seqno is not None:
+                # Expected all sequence numbers. But you can safely disable
+                # this check.
+                assert seqno == prev_seqno + 1, '%s+1 != %s' % (
+                    seqno, prev_seqno)
+                pass
+            prev_seqno = seqno
+
+            yield IFP(date=date, seqno=seqno, data=data)
+
+
+def main(logname, pcapname):
+    with open(sys.argv[1], 'r') as infile:
+        log = SpandspLog(infile)
+
+        # with open(sys.argv[2], 'xb') as outfile:  # py3 exclusive write, bin
+        create_or_fail = os.O_CREAT | os.O_EXCL | os.O_WRONLY
+        try:
+            fd = os.open(sys.argv[2], create_or_fail, 0o600)
+        except Exception:
+            raise
+        else:
+            with os.fdopen(fd, 'wb') as outfile:
+                pcap = FaxPcap(outfile)
+                for data in log:
+                    pcap.add(data)
+
+
+if __name__ == '__main__':
+    if len(sys.argv) != 3:
+        sys.stderr.write('Usage: {} LOGFILE PCAP\n'.format(sys.argv[0]))
+        sys.exit(1)
+
+    main(sys.argv[1], sys.argv[2])