PCAP file library

Introduction

Ryu PCAP file library helps you to read/write PCAP file which file format are described in The Wireshark Wiki.

Reading PCAP file

For loading the packet data containing in PCAP files, you can use pcaplib.Reader.

class ryu.lib.pcaplib.Reader(file_obj)

PCAP file reader

Argument	Description
file_obj	File object which reading PCAP file in binary mode

Example of usage:

from ryu.lib import pcaplib
from ryu.lib.packet import packet

frame_count = 0
# iterate pcaplib.Reader that yields (timestamp, packet_data)
# in the PCAP file
for ts, buf in pcaplib.Reader(open('test.pcap', 'rb')):
    frame_count += 1
    pkt = packet.Packet(buf)
    print("%d, %f, %s" % (frame_count, ts, pkt))

Writing PCAP file

For dumping the packet data which your RyuApp received, you can use pcaplib.Writer.

class ryu.lib.pcaplib.Writer(file_obj, snaplen=65535, network=1)

PCAP file writer

Argument	Description
file_obj	File object which writing PCAP file in binary mode
snaplen	Max length of captured packets (in octets)
network	Data link type. (e.g. 1 for Ethernet, see tcpdump.org for details)

Example of usage:

...
from ryu.lib import pcaplib


class SimpleSwitch13(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(SimpleSwitch13, self).__init__(*args, **kwargs)
        self.mac_to_port = {}

        # Create pcaplib.Writer instance with a file object
        # for the PCAP file
        self.pcap_writer = pcaplib.Writer(open('mypcap.pcap', 'wb'))

    ...

    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def _packet_in_handler(self, ev):
        # Dump the packet data into PCAP file
        self.pcap_writer.write_pkt(ev.msg.data)

        ...