netflow/test_netflow.py

#!/usr/bin/env python3

"""
This file contains tests for the NetFlow collector for versions 1, 5 and 9.
The test packets (defined below as hex streams) were extracted from "real"
softflowd exports based on a sample PCAP capture file.

Copyright 2017-2020 Dominik Pataky <dev@bitkeks.eu>
Licensed under MIT License. See LICENSE.
"""
import gzip
import ipaddress
import json
import queue
import random
import socket
import subprocess
import sys
import time
import unittest

from netflow.collector import ThreadedNetFlowListener

# TODO: tests with 500 packets fail with delay=0. Probably a problem with UDP sockets buffer

# The flowset with 2 templates (IPv4 and IPv6) and 8 flows with data
PACKET_V9_TEMPLATE = "0009000a000000035c9f55980000000100000000000000400400000e00080004000c000400150004" \
                     "001600040001000400020004000a0004000e000400070002000b00020004000100060001003c0001" \
                     "00050001000000400800000e001b0010001c001000150004001600040001000400020004000a0004" \
                     "000e000400070002000b00020004000100060001003c000100050001040001447f0000017f000001" \
                     "fb3c1aaafb3c18fd000190100000004b00000000000000000050942c061b04007f0000017f000001" \
                     "fb3c1aaafb3c18fd00000f94000000360000000000000000942c0050061f04007f0000017f000001" \
                     "fb3c1cfcfb3c1a9b0000d3fc0000002a000000000000000000509434061b04007f0000017f000001" \
                     "fb3c1cfcfb3c1a9b00000a490000001e000000000000000094340050061f04007f0000017f000001" \
                     "fb3bb82cfb3ba48b000002960000000300000000000000000050942a061904007f0000017f000001" \
                     "fb3bb82cfb3ba48b00000068000000020000000000000000942a0050061104007f0000017f000001" \
                     "fb3c1900fb3c18fe0000004c0000000100000000000000000035b3c9110004007f0000017f000001" \
                     "fb3c1900fb3c18fe0000003c000000010000000000000000b3c9003511000400"

# This packet is special. We take PACKET_V9_TEMPLATE and re-order the templates and flows.
# The first line is the header, the smaller lines the templates and the long lines the flows (limited to 80 chars)
PACKET_V9_TEMPLATE_MIXED = ("0009000a000000035c9f55980000000100000000"  # header
                            "040001447f0000017f000001fb3c1aaafb3c18fd000190100000004b00000000000000000050942c"
                            "061b04007f0000017f000001fb3c1aaafb3c18fd00000f94000000360000000000000000942c0050"
                            "061f04007f0000017f000001fb3c1cfcfb3c1a9b0000d3fc0000002a000000000000000000509434"
                            "061b04007f0000017f000001fb3c1cfcfb3c1a9b00000a490000001e000000000000000094340050"
                            "061f04007f0000017f000001fb3bb82cfb3ba48b000002960000000300000000000000000050942a"
                            "061904007f0000017f000001fb3bb82cfb3ba48b00000068000000020000000000000000942a0050"
                            "061104007f0000017f000001fb3c1900fb3c18fe0000004c0000000100000000000000000035b3c9"
                            "110004007f0000017f000001fb3c1900fb3c18fe0000003c000000010000000000000000b3c90035"
                            "11000400"  # end of flow segments
                            "000000400400000e00080004000c000400150004001600040001000400020004"  # template 1024
                            "000a0004000e000400070002000b00020004000100060001003c000100050001"
                            "000000400800000e001b0010001c001000150004001600040001000400020004"  # template 2048
                            "000a0004000e000400070002000b00020004000100060001003c000100050001")

# Three packets without templates, each with 12 flows, anonymized
PACKETS_V9 = [
    "0009000c000000035c9f55980000000200000000040001e47f0000017f000001fb3c1a17fb3c19fd"
    "000001480000000200000000000000000035ea82110004007f0000017f000001fb3c1a17fb3c19fd"
    "0000007a000000020000000000000000ea820035110004007f0000017f000001fb3c1a17fb3c19fd"
    "000000f80000000200000000000000000035c6e2110004007f0000017f000001fb3c1a17fb3c19fd"
    "0000007a000000020000000000000000c6e20035110004007f0000017f000001fb3c1a9efb3c1a9c"
    "0000004c0000000100000000000000000035adc1110004007f0000017f000001fb3c1a9efb3c1a9c"
    "0000003c000000010000000000000000adc10035110004007f0000017f000001fb3c1b74fb3c1b72"
    "0000004c0000000100000000000000000035d0b3110004007f0000017f000001fb3c1b74fb3c1b72"
    "0000003c000000010000000000000000d0b30035110004007f0000017f000001fb3c2f59fb3c1b71"
    "00001a350000000a000000000000000000509436061b04007f0000017f000001fb3c2f59fb3c1b71"
    "0000038a0000000a000000000000000094360050061b04007f0000017f000001fb3c913bfb3c9138"
    "0000004c0000000100000000000000000035e262110004007f0000017f000001fb3c913bfb3c9138"
    "0000003c000000010000000000000000e262003511000400",

    "0009000c000000035c9f55980000000300000000040001e47f0000017f000001fb3ca523fb3c913b"
    "0000030700000005000000000000000000509438061b04007f0000017f000001fb3ca523fb3c913b"
    "000002a200000005000000000000000094380050061b04007f0000017f000001fb3f7fe1fb3dbc97"
    "0002d52800000097000000000000000001bb8730061b04007f0000017f000001fb3f7fe1fb3dbc97"
    "0000146c000000520000000000000000873001bb061f04007f0000017f000001fb3d066ffb3d066c"
    "0000004c0000000100000000000000000035e5bd110004007f0000017f000001fb3d066ffb3d066c"
    "0000003c000000010000000000000000e5bd0035110004007f0000017f000001fb3d1a61fb3d066b"
    "000003060000000500000000000000000050943a061b04007f0000017f000001fb3d1a61fb3d066b"
    "000002a2000000050000000000000000943a0050061b04007f0000017f000001fb3fed00fb3f002c"
    "0000344000000016000000000000000001bbae50061f04007f0000017f000001fb3fed00fb3f002c"
    "00000a47000000120000000000000000ae5001bb061b04007f0000017f000001fb402f17fb402a75"
    "0003524c000000a5000000000000000001bbc48c061b04007f0000017f000001fb402f17fb402a75"
    "000020a60000007e0000000000000000c48c01bb061f0400",

    "0009000c000000035c9f55980000000400000000040001e47f0000017f000001fb3d7ba2fb3d7ba0"
    "0000004c0000000100000000000000000035a399110004007f0000017f000001fb3d7ba2fb3d7ba0"
    "0000003c000000010000000000000000a3990035110004007f0000017f000001fb3d8f85fb3d7b9f"
    "000003070000000500000000000000000050943c061b04007f0000017f000001fb3d8f85fb3d7b9f"
    "000002a2000000050000000000000000943c0050061b04007f0000017f000001fb3d9165fb3d7f6d"
    "0000c97b0000002a000000000000000001bbae48061b04007f0000017f000001fb3d9165fb3d7f6d"
    "000007f40000001a0000000000000000ae4801bb061b04007f0000017f000001fb3dbc96fb3dbc7e"
    "0000011e0000000200000000000000000035bd4f110004007f0000017f000001fb3dbc96fb3dbc7e"
    "0000008e000000020000000000000000bd4f0035110004007f0000017f000001fb3ddbb3fb3c1a18"
    "0000bfee0000002f00000000000000000050ae56061b04007f0000017f000001fb3ddbb3fb3c1a18"
    "00000982000000270000000000000000ae560050061b04007f0000017f000001fb3ddbb3fb3c1a18"
    "0000130e0000001200000000000000000050e820061b04007f0000017f000001fb3ddbb3fb3c1a18"
    "0000059c000000140000000000000000e8200050061b0400"
]

# Example export for v1 which contains two flows from one ICMP ping request/reply session
PACKET_V1 = "000100020001189b5e80c32c2fd41848ac110002ac11000100000000000000000000000a00000348" \
            "000027c700004af100000800000001000000000000000000ac110001ac1100020000000000000000" \
            "0000000a00000348000027c700004af100000000000001000000000000000000"

# Example export for v5 which contains three flows, two for ICMP ping and one multicast on interface (224.0.0.251)
PACKET_V5 = "00050003000379a35e80c58622a55ab00000000000000000ac110002ac1100010000000000000000" \
            "0000000a0000034800002f4c0000527600000800000001000000000000000000ac110001ac110002" \
            "00000000000000000000000a0000034800002f4c0000527600000000000001000000000000000000" \
            "ac110001e00000fb000000000000000000000001000000a90000e01c0000e01c14e914e900001100" \
            "0000000000000000"

# Invalid export hex stream
PACKET_INVALID = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"

CONNECTION = ('127.0.0.1', 1337)
NUM_PACKETS = 500


def emit_packets(packets, delay=0.0001):
    """Send the provided packets to the listener"""
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    for p in packets:
        sock.sendto(bytes.fromhex(p), CONNECTION)
        time.sleep(delay)
    sock.close()


def send_recv_packets(packets, delay=0.0001) -> (list, float, float):
    """Starts a listener, send packets, receives packets

    returns a tuple: ([(ts, export), ...], time_started_sending, time_stopped_sending)
    """
    listener = ThreadedNetFlowListener(*CONNECTION)
    tstart = time.time()
    emit_packets(packets, delay=delay)
    time.sleep(0.5)  # Allow packets to be sent and recieved
    tend = time.time()
    listener.start()

    pkts = []
    while True:
        try:
            pkts.append(listener.get(timeout=0.5))
        except queue.Empty:
            break
    listener.stop()
    listener.join()
    return pkts, tstart, tend


class TestFlowExport(unittest.TestCase):
    def _test_recv_all_packets(self, num, template_idx, delay=0.0001):
        """Fling packets at the server and test that it receives them all"""

        def gen_pkts(n, idx):
            for x in range(n):
                if x == idx:
                    yield PACKET_V9_TEMPLATE
                else:
                    yield random.choice(PACKETS_V9)

        pkts, tstart, tend = send_recv_packets(gen_pkts(num, template_idx), delay=delay)

        # check number of packets
        self.assertEqual(len(pkts), num)

        # check timestamps are when packets were sent, not processed
        self.assertTrue(all(tstart < p.ts < tend for p in pkts))

        # check number of "things" in the packets (flows + templates)
        # template packet = 10 things
        # other packets = 12 things
        self.assertEqual(sum(p.export.header.count for p in pkts), (num - 1) * 12 + 10)

        # check number of flows in the packets
        # template packet = 8 flows (2 templates)
        # other packets = 12 flows
        self.assertEqual(sum(len(p.export.flows) for p in pkts), (num - 1) * 12 + 8)

    def test_recv_all_packets_template_first(self):
        """Test all packets are received when the template is sent first"""
        self._test_recv_all_packets(NUM_PACKETS, 0)

    def test_recv_all_packets_template_middle(self):
        """Test all packets are received when the template is sent in the middle"""
        self._test_recv_all_packets(NUM_PACKETS, NUM_PACKETS // 2)

    def test_recv_all_packets_template_last(self):
        """Test all packets are received when the template is sent last"""
        self._test_recv_all_packets(NUM_PACKETS, NUM_PACKETS - 1)

    def test_recv_all_packets_slowly(self):
        """Test all packets are received when things are sent slooooowwwwwwwwlllllllyyyyyy"""
        self._test_recv_all_packets(3, 0, delay=1)

    def test_ignore_invalid_packets(self):
        """Test that invalid packets log a warning but are otherwise ignored"""
        with self.assertLogs(level='WARNING'):
            pkts, _, _ = send_recv_packets([
                PACKET_INVALID, PACKET_V9_TEMPLATE, random.choice(PACKETS_V9), PACKET_INVALID,
                random.choice(PACKETS_V9), PACKET_INVALID
            ])
        self.assertEqual(len(pkts), 3)

    def test_recv_v1_packet(self):
        """Test NetFlow v1 packet parsing"""
        pkts, _, _ = send_recv_packets([PACKET_V1])
        self.assertEqual(len(pkts), 1)

        # Take the parsed packet and check meta data
        p = pkts[0]
        self.assertEqual(p.client[0], "127.0.0.1")  # collector listens locally
        self.assertEqual(len(p.export.flows), 2)  # ping request and reply
        self.assertEqual(p.export.header.count, 2)  # same value, in header
        self.assertEqual(p.export.header.version, 1)

        # Check specific IP address contained in a flow.
        # Since it might vary which flow of the pair is epxorted first, check both
        flow = p.export.flows[0]
        self.assertIn(
            ipaddress.ip_address(flow.IPV4_SRC_ADDR),  # convert to ipaddress obj because value is int
            [ipaddress.ip_address("172.17.0.1"), ipaddress.ip_address("172.17.0.2")]
        )
        self.assertEqual(flow.PROTO, 1)  # ICMP

    def test_recv_v5_packet(self):
        """Test NetFlow v5 packet parsing"""
        pkts, _, _ = send_recv_packets([PACKET_V5])
        self.assertEqual(len(pkts), 1)

        p = pkts[0]
        self.assertEqual(p.client[0], "127.0.0.1")
        self.assertEqual(len(p.export.flows), 3)  # ping request and reply, one multicast
        self.assertEqual(p.export.header.count, 3)
        self.assertEqual(p.export.header.version, 5)

        # Check specific IP address contained in a flow.
        # Since it might vary which flow of the pair is epxorted first, check both
        flow = p.export.flows[0]
        self.assertIn(
            ipaddress.ip_address(flow.IPV4_SRC_ADDR),  # convert to ipaddress obj because value is int
            [ipaddress.ip_address("172.17.0.1"), ipaddress.ip_address("172.17.0.2")]  # matches multicast packet too
        )
        self.assertEqual(flow.PROTO, 1)  # ICMP

    def test_recv_v9_packet(self):
        """Test NetFlow v9 packet parsing"""

        # send packet without any template, must fail to parse (packets are queued)
        pkts, _, _ = send_recv_packets([PACKETS_V9[0]])
        self.assertEqual(len(pkts), 0)  # no export is parsed due to missing template

        # send packet with two templates and eight flows, should parse correctly since the templates are known
        pkts, _, _ = send_recv_packets([PACKET_V9_TEMPLATE])
        self.assertEqual(len(pkts), 1)

        # and again, but with the templates at the end in the packet
        pkts, _, _ = send_recv_packets([PACKET_V9_TEMPLATE_MIXED])
        self.assertEqual(len(pkts), 1)
        p = pkts[0]
        self.assertEqual(p.client[0], "127.0.0.1")
        self.assertEqual(len(p.export.flows), 8)  # count flows
        self.assertEqual(len(p.export.templates), 2)  # count new templates

        # Inspect contents of specific flows
        flow = p.export.flows[0]
        self.assertEqual(flow.PROTOCOL, 6)  # TCP
        self.assertEqual(flow.L4_SRC_PORT, 80)
        self.assertEqual(flow.IPV4_SRC_ADDR, "127.0.0.1")

        flow = p.export.flows[-1]  # last flow
        self.assertEqual(flow.PROTOCOL, 17)  # UDP
        self.assertEqual(flow.L4_DST_PORT, 53)

        # send template and multiple export packets
        pkts, _, _ = send_recv_packets([PACKET_V9_TEMPLATE, *PACKETS_V9])
        self.assertEqual(len(pkts), 4)
        self.assertEqual(pkts[0].export.header.version, 9)

        # check amount of flows across all packets
        total_flows = 0
        for packet in pkts:
            total_flows += len(packet.export.flows)
        self.assertEqual(total_flows, 8 + 12 + 12 + 12)

    def test_analyzer(self):
        """Test the analyzer by producing some packets, parsing them and then calling the analyzer
        in a subprocess, piping in a created gzip JSON collection (as if it is coming from a file).
        """
        # First create and parse some packets, which should get exported
        pkts, _, _ = send_recv_packets([PACKET_V9_TEMPLATE, *PACKETS_V9])

        # Now the pkts must be transformed from their data structure to the "gzipped JSON representation",
        # which the collector uses for persistant storage.
        data_dicts = []  # list holding all entries
        for p in pkts:  # each pkt has its own entry with timestamp as key
            data_dicts.append({p.ts: {
                "client": p.client,
                "flows": [f.data for f in p.export.flows]
            }})
        data = "\n".join([json.dumps(dd) for dd in data_dicts])  # join all entries together by newlines

        # Different stdout/stderr arguments for backwards compatibility
        pipe_output_param = {"capture_output": True}
        if sys.version_info < (3, 7):  # capture_output was added in Python 3.7
            pipe_output_param = {
                "stdout": subprocess.PIPE,
                "stderr": subprocess.PIPE
            }

        # Analyzer takes gzipped input either via stdin or from a file (here: stdin)
        gzipped_input = gzip.compress(data.encode())  # encode to unicode

        # Run analyzer as CLI script with no packets ignored (parameter)
        analyzer = subprocess.run(
            [sys.executable, '-m', 'netflow.analyzer', '-p', '0'],
            input=gzipped_input,
            **pipe_output_param
        )

        # If stderr has content, print it
        if analyzer.stderr:
            print(analyzer.stderr.decode())

        # Every 2 flows are written as a single line (any extras are dropped)
        num_flows = sum(len(list(item.values())[0]["flows"]) for item in data_dicts)
        self.assertEqual(len(analyzer.stdout.splitlines()) - 2, num_flows // 2)  # ignore two header lines

        # make sure there are no errors
        self.assertEqual(analyzer.stderr, b"")


if __name__ == '__main__':
    unittest.main()