Inheritance diagram for FaxPcap:

Collaboration diagram for FaxPcap:

Public Member Functions
	__init__ (self, outfile)

	add (self, ifp)

Data Fields
	date

	outfile

	prev_data

	seqno

	udpseqno

Static Public Attributes
	PCAP_PREAMBLE

Protected Member Functions
	_add_garbage (self, date)

	_add_preamble (self)

	_make_packet (self, ifp_data, is_ifp=True)

Detailed Description

Definition at line 56 of file spandspflow2pcap.py.

Constructor & Destructor Documentation

◆ init()

__init__	(	self,
		outfile
	)

Definition at line 62 of file spandspflow2pcap.py.

    def __init__(self, outfile):
        self.outfile = outfile
        self.date = None
        self.seqno = None
        self.udpseqno = 128
        self.prev_data = None
 
        # Only do this if at pos 0?
 

Member Function Documentation

◆ _add_garbage()

_add_garbage	(	self,
		date
	)

protected

Definition at line 122 of file spandspflow2pcap.py.

    def _add_garbage(self, date):
        if self.date is None or date > self.date:
            self.date = date
 
        self.seqno = 0xffff
        self.outfile.write(self._make_packet(
            bytearray(b'GARBAGE'), is_ifp=False))
 

References FaxPcap._make_packet(), FaxPcap.date, logmsg.date, FaxPcap.outfile, FaxPcap.seqno, ast_bridge_hook_timer_parms.seqno, ast_frame.seqno, rtp_transport_wide_cc_packet_statistics.seqno, ast_rtp.seqno, and multicast_rtp.seqno.

Referenced by FaxPcap.add().

◆ _add_preamble()

_add_preamble ( self )

protected

Definition at line 119 of file spandspflow2pcap.py.

    def _add_preamble(self):
        self.outfile.write(self.PCAP_PREAMBLE)
 

References FaxPcap.outfile, and FaxPcap.PCAP_PREAMBLE.

Referenced by FaxPcap.add().

◆ _make_packet()

_make_packet	(	self,
		ifp_data,
		is_ifp = `True`
	)

protected

Definition at line 130 of file spandspflow2pcap.py.

    def _make_packet(self, ifp_data, is_ifp=True):
        sum16 = bytearray(b'\x43\x21')  # the OS fixes the checksums for us
 
        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:
            data.extend(ifp_data)
            prev_data = None
 
        if prev_data:
            if LOSSY and (self.seqno % 3) == 2:
                self.udpseqno += 1
                raise SkipPacket()
 
            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
 
        return packet
 
 

References FaxPcap.date, logmsg.date, len(), FaxPcap.prev_data, FaxPcap.seqno, ast_bridge_hook_timer_parms.seqno, ast_frame.seqno, rtp_transport_wide_cc_packet_statistics.seqno, ast_rtp.seqno, multicast_rtp.seqno, and FaxPcap.udpseqno.

Referenced by FaxPcap._add_garbage(), and FaxPcap.add().

◆ add()

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)
- ...

Definition at line 71 of file spandspflow2pcap.py.

    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)
 
            # 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])))
 
        # 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)
 
        # Add packet.
        self.seqno = ifp.seqno
        try:
            self.outfile.write(self._make_packet(ifp.data))
        except SkipPacket:
            pass
 

References FaxPcap._add_garbage(), FaxPcap._add_preamble(), FaxPcap._make_packet(), FaxPcap.add(), FaxPcap.date, logmsg.date, spandspflow2pcap.IFP, FaxPcap.outfile, replace(), FaxPcap.seqno, ast_bridge_hook_timer_parms.seqno, ast_frame.seqno, rtp_transport_wide_cc_packet_statistics.seqno, ast_rtp.seqno, and multicast_rtp.seqno.

Referenced by FaxPcap.add().

Field Documentation

◆ date

date

Definition at line 64 of file spandspflow2pcap.py.

Referenced by FaxPcap._add_garbage(), FaxPcap._make_packet(), and FaxPcap.add().

◆ outfile

outfile

Definition at line 63 of file spandspflow2pcap.py.

Referenced by FaxPcap._add_garbage(), FaxPcap._add_preamble(), and FaxPcap.add().

◆ PCAP_PREAMBLE

PCAP_PREAMBLE

static

Initial value:

=  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')

Definition at line 57 of file spandspflow2pcap.py.

Referenced by FaxPcap._add_preamble().

◆ prev_data

prev_data

Definition at line 67 of file spandspflow2pcap.py.

Referenced by FaxPcap._make_packet().

◆ seqno

seqno

Definition at line 65 of file spandspflow2pcap.py.

Referenced by FaxPcap._add_garbage(), FaxPcap._make_packet(), and FaxPcap.add().

◆ udpseqno

udpseqno

Definition at line 66 of file spandspflow2pcap.py.

Referenced by FaxPcap._make_packet().

The documentation for this class was generated from the following file:

spandspflow2pcap.py

Public Member Functions

Data Fields

Static Public Attributes

Protected Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ __init__()

Member Function Documentation

◆ _add_garbage()

◆ _add_preamble()

◆ _make_packet()

◆ add()

Field Documentation

◆ date

◆ outfile

◆ PCAP_PREAMBLE

◆ prev_data

◆ seqno

◆ udpseqno

◆ init()