test/util.py

""" test framework utilities """

import socket
import sys
import os.path
from abc import abstractmethod, ABCMeta
from scapy.utils6 import in6_mactoifaceid

from scapy.layers.l2 import Ether
from scapy.packet import Raw
from scapy.layers.inet import IP
from scapy.layers.inet6 import IPv6, IPv6ExtHdrFragment, IPv6ExtHdrRouting,\
    IPv6ExtHdrHopByHop
from scapy.utils import hexdump
from socket import AF_INET6
from io import BytesIO
from vpp_mac import mactobinary


def ppp(headline, packet):
    """ Return string containing the output of scapy packet.show() call. """
    o = BytesIO()
    old_stdout = sys.stdout
    sys.stdout = o
    print(headline)
    hexdump(packet)
    print("")
    packet.show()
    sys.stdout = old_stdout
    return o.getvalue()


def ppc(headline, capture, limit=10):
    """ Return string containing ppp() printout for a capture.

    :param headline: printed as first line of output
    :param capture: packets to print
    :param limit: limit the print to # of packets
    """
    if not capture:
        return headline
    tail = ""
    if limit < len(capture):
        tail = "\nPrint limit reached, %s out of %s packets printed" % (
            limit, len(capture))
    body = "".join([ppp("Packet #%s:" % count, p)
                    for count, p in zip(range(0, limit), capture)])
    return "%s\n%s%s" % (headline, body, tail)


def ip4_range(ip4, s, e):
    tmp = ip4.rsplit('.', 1)[0]
    return ("%s.%d" % (tmp, i) for i in range(s, e))


def ip4n_range(ip4n, s, e):
    ip4 = socket.inet_ntop(socket.AF_INET, ip4n)
    return (socket.inet_pton(socket.AF_INET, ip)
            for ip in ip4_range(ip4, s, e))


def mk_ll_addr(mac):
    euid = in6_mactoifaceid(mac)
    addr = "fe80::" + euid
    return addr


def ip6_normalize(ip6):
    return socket.inet_ntop(socket.AF_INET6,
                            socket.inet_pton(socket.AF_INET6, ip6))


def get_core_path(tempdir):
    return "%s/%s" % (tempdir, get_core_pattern())


def is_core_present(tempdir):
    return os.path.isfile(get_core_path(tempdir))


def get_core_pattern():
    with open("/proc/sys/kernel/core_pattern", "r") as f:
        corefmt = f.read().strip()
    return corefmt


def check_core_path(logger, core_path):
    corefmt = get_core_pattern()
    if corefmt.startswith("|"):
        logger.error(
            "WARNING: redirecting the core dump through a"
            " filter may result in truncated dumps.")
        logger.error(
            "   You may want to check the filter settings"
            " or uninstall it and edit the"
            " /proc/sys/kernel/core_pattern accordingly.")
        logger.error(
            "   current core pattern is: %s" % corefmt)


class NumericConstant(object):
    __metaclass__ = ABCMeta

    desc_dict = {}

    @abstractmethod
    def __init__(self, value):
        self._value = value

    def __int__(self):
        return self._value

    def __long__(self):
        return self._value

    def __str__(self):
        if self._value in self.desc_dict:
            return self.desc_dict[self._value]
        return ""


class Host(object):
    """ Generic test host "connected" to VPPs interface. """

    @property
    def mac(self):
        """ MAC address """
        return self._mac

    @property
    def bin_mac(self):
        """ MAC address """
        return mactobinary(self._mac)

    @property
    def ip4(self):
        """ IPv4 address - string """
        return self._ip4

    @property
    def ip4n(self):
        """ IPv4 address of remote host - raw, suitable as API parameter."""
        return socket.inet_pton(socket.AF_INET, self._ip4)

    @property
    def ip6(self):
        """ IPv6 address - string """
        return self._ip6

    @property
    def ip6n(self):
        """ IPv6 address of remote host - raw, suitable as API parameter."""
        return socket.inet_pton(socket.AF_INET6, self._ip6)

    @property
    def ip6_ll(self):
        """ IPv6 link-local address - string """
        return self._ip6_ll

    @property
    def ip6n_ll(self):
        """ IPv6 link-local address of remote host -
        raw, suitable as API parameter."""
        return socket.inet_pton(socket.AF_INET6, self._ip6_ll)

    def __eq__(self, other):
        if isinstance(other, Host):
            return (self.mac == other.mac and
                    self.ip4 == other.ip4 and
                    self.ip6 == other.ip6 and
                    self.ip6_ll == other.ip6_ll)
        else:
            return False

    def __ne__(self, other):
        return not self.__eq__(other)

    def __repr__(self):
        return "Host { mac:%s ip4:%s ip6:%s ip6_ll:%s }" % (self.mac,
                                                            self.ip4,
                                                            self.ip6,
                                                            self.ip6_ll)

    def __hash__(self):
        return hash(self.__repr__())

    def __init__(self, mac=None, ip4=None, ip6=None, ip6_ll=None):
        self._mac = mac
        self._ip4 = ip4
        self._ip6 = ip6
        self._ip6_ll = ip6_ll


class ForeignAddressFactory(object):
    count = 0
    prefix_len = 24
    net_template = '10.10.10.{}'
    net = net_template.format(0) + '/' + str(prefix_len)

    def get_ip4(self):
        if self.count > 255:
            raise Exception("Network host address exhaustion")
        self.count += 1
        return self.net_template.format(self.count)


class L4_Conn():
    """ L4 'connection' tied to two VPP interfaces """

    def __init__(self, testcase, if1, if2, af, l4proto, port1, port2):
        self.testcase = testcase
        self.ifs = [None, None]
        self.ifs[0] = if1
        self.ifs[1] = if2
        self.address_family = af
        self.l4proto = l4proto
        self.ports = [None, None]
        self.ports[0] = port1
        self.ports[1] = port2
        self

    def pkt(self, side, l4args={}, payload="x"):
        is_ip6 = 1 if self.address_family == AF_INET6 else 0
        s0 = side
        s1 = 1 - side
        src_if = self.ifs[s0]
        dst_if = self.ifs[s1]
        layer_3 = [IP(src=src_if.remote_ip4, dst=dst_if.remote_ip4),
                   IPv6(src=src_if.remote_ip6, dst=dst_if.remote_ip6)]
        merged_l4args = {'sport': self.ports[s0], 'dport': self.ports[s1]}
        merged_l4args.update(l4args)
        p = (Ether(dst=src_if.local_mac, src=src_if.remote_mac) /
             layer_3[is_ip6] /
             self.l4proto(**merged_l4args) /
             Raw(payload))
        return p

    def send(self, side, flags=None, payload=""):
        l4args = {}
        if flags is not None:
            l4args['flags'] = flags
        self.ifs[side].add_stream(self.pkt(side,
                                           l4args=l4args, payload=payload))
        self.ifs[1 - side].enable_capture()
        self.testcase.pg_start()

    def recv(self, side):
        p = self.ifs[side].wait_for_packet(1)
        return p

    def send_through(self, side, flags=None, payload=""):
        self.send(side, flags, payload)
        p = self.recv(1 - side)
        return p

    def send_pingpong(self, side, flags1=None, flags2=None):
        p1 = self.send_through(side, flags1)
        p2 = self.send_through(1 - side, flags2)
        return [p1, p2]


class L4_CONN_SIDE:
    L4_CONN_SIDE_ZERO = 0
    L4_CONN_SIDE_ONE = 1


class LoggerWrapper(object):
    def __init__(self, logger=None):
        self._logger = logger

    def debug(self, *args, **kwargs):
        if self._logger:
            self._logger.debug(*args, **kwargs)

    def error(self, *args, **kwargs):
        if self._logger:
            self._logger.error(*args, **kwargs)


def fragment_rfc791(packet, fragsize, _logger=None):
    """
    Fragment an IPv4 packet per RFC 791
    :param packet: packet to fragment
    :param fragsize: size at which to fragment
    :note: IP options are not supported
    :returns: list of fragments
    """
    logger = LoggerWrapper(_logger)
    logger.debug(ppp("Fragmenting packet:", packet))
    packet = packet.__class__(str(packet))  # recalculate all values
    if len(packet[IP].options) > 0:
        raise Exception("Not implemented")
    if len(packet) <= fragsize:
        return [packet]

    pre_ip_len = len(packet) - len(packet[IP])
    ip_header_len = packet[IP].ihl * 4
    hex_packet = str(packet)
    hex_headers = hex_packet[:(pre_ip_len + ip_header_len)]
    hex_payload = hex_packet[(pre_ip_len + ip_header_len):]

    pkts = []
    ihl = packet[IP].ihl
    otl = len(packet[IP])
    nfb = (fragsize - pre_ip_len - ihl * 4) / 8
    fo = packet[IP].frag

    p = packet.__class__(hex_headers + hex_payload[:nfb * 8])
    p[IP].flags = "MF"
    p[IP].frag = fo
    p[IP].len = ihl * 4 + nfb * 8
    del p[IP].chksum
    pkts.append(p)

    p = packet.__class__(hex_headers + hex_payload[nfb * 8:])
    p[IP].len = otl - nfb * 8
    p[IP].frag = fo + nfb
    del p[IP].chksum

    more_fragments = fragment_rfc791(p, fragsize, _logger)
    pkts.extend(more_fragments)

    return pkts


def fragment_rfc8200(packet, identification, fragsize, _logger=None):
    """
    Fragment an IPv6 packet per RFC 8200
    :param packet: packet to fragment
    :param fragsize: size at which to fragment
    :note: IP options are not supported
    :returns: list of fragments
    """
    logger = LoggerWrapper(_logger)
    packet = packet.__class__(str(packet))  # recalculate all values
    if len(packet) <= fragsize:
        return [packet]
    logger.debug(ppp("Fragmenting packet:", packet))
    pkts = []
    counter = 0
    routing_hdr = None
    hop_by_hop_hdr = None
    upper_layer = None
    seen_ipv6 = False
    ipv6_nr = -1
    l = packet.getlayer(counter)
    while l is not None:
        if l.__class__ is IPv6:
            if seen_ipv6:
                # ignore 2nd IPv6 header and everything below..
                break
            ipv6_nr = counter
            seen_ipv6 = True
        elif l.__class__ is IPv6ExtHdrFragment:
            raise Exception("Already fragmented")
        elif l.__class__ is IPv6ExtHdrRouting:
            routing_hdr = counter
        elif l.__class__ is IPv6ExtHdrHopByHop:
            hop_by_hop_hdr = counter
        elif seen_ipv6 and not upper_layer and \
                not l.__class__.__name__.startswith('IPv6ExtHdr'):
            upper_layer = counter
        counter = counter + 1
        l = packet.getlayer(counter)

    logger.debug(
        "Layers seen: IPv6(#%s), Routing(#%s), HopByHop(#%s), upper(#%s)" %
        (ipv6_nr, routing_hdr, hop_by_hop_hdr, upper_layer))

    if upper_layer is None:
        raise Exception("Upper layer header not found in IPv6 packet")

    last_per_fragment_hdr = ipv6_nr
    if routing_hdr is None:
        if hop_by_hop_hdr is not None:
            last_per_fragment_hdr = hop_by_hop_hdr
    else:
        last_per_fragment_hdr = routing_hdr
    logger.debug("Last per-fragment hdr is #%s" % (last_per_fragment_hdr))

    per_fragment_headers = packet.copy()
    per_fragment_headers[last_per_fragment_hdr].remove_payload()
    logger.debug(ppp("Per-fragment headers:", per_fragment_headers))

    ext_and_upper_layer = packet.getlayer(last_per_fragment_hdr)[1]
    hex_payload = str(ext_and_upper_layer)
    logger.debug("Payload length is %s" % len(hex_payload))
    logger.debug(ppp("Ext and upper layer:", ext_and_upper_layer))

    fragment_ext_hdr = IPv6ExtHdrFragment()
    logger.debug(ppp("Fragment header:", fragment_ext_hdr))

    if len(per_fragment_headers) + len(fragment_ext_hdr) +\
            len(ext_and_upper_layer) - len(ext_and_upper_layer.payload)\
            > fragsize:
        raise Exception("Cannot fragment this packet - MTU too small "
                        "(%s, %s, %s, %s, %s)" % (
                            len(per_fragment_headers), len(fragment_ext_hdr),
                            len(ext_and_upper_layer),
                            len(ext_and_upper_layer.payload), fragsize))

    orig_nh = packet[IPv6].nh
    p = per_fragment_headers
    del p[IPv6].plen
    del p[IPv6].nh
    p = p / fragment_ext_hdr
    del p[IPv6ExtHdrFragment].nh
    first_payload_len_nfb = (fragsize - len(p)) / 8
    p = p / Raw(hex_payload[:first_payload_len_nfb * 8])
    del p[IPv6].plen
    p[IPv6ExtHdrFragment].nh = orig_nh
    p[IPv6ExtHdrFragment].id = identification
    p[IPv6ExtHdrFragment].offset = 0
    p[IPv6ExtHdrFragment].m = 1
    p = p.__class__(str(p))
    logger.debug(ppp("Fragment %s:" % len(pkts), p))
    pkts.append(p)
    offset = first_payload_len_nfb * 8
    logger.debug("Offset after first fragment: %s" % offset)
    while len(hex_payload) > offset:
        p = per_fragment_headers
        del p[IPv6].plen
        del p[IPv6].nh
        p = p / fragment_ext_hdr
        del p[IPv6ExtHdrFragment].nh
        l_nfb = (fragsize - len(p)) / 8
        p = p / Raw(hex_payload[offset:offset + l_nfb * 8])
        p[IPv6ExtHdrFragment].nh = orig_nh
        p[IPv6ExtHdrFragment].id = identification
        p[IPv6ExtHdrFragment].offset = offset / 8
        p[IPv6ExtHdrFragment].m = 1
        p = p.__class__(str(p))
        logger.debug(ppp("Fragment %s:" % len(pkts), p))
        pkts.append(p)
        offset = offset + l_nfb * 8

    pkts[-1][IPv6ExtHdrFragment].m = 0  # reset more-flags in last fragment

    return pkts


def reassemble4_core(listoffragments, return_ip):
    buffer = BytesIO()
    first = listoffragments[0]
    buffer.seek(20)
    for pkt in listoffragments:
        buffer.seek(pkt[IP].frag*8)
        buffer.write(bytes(pkt[IP].payload))
    first.len = len(buffer.getvalue()) + 20
    first.flags = 0
    del(first.chksum)
    if return_ip:
        header = bytes(first[IP])[:20]
        return first[IP].__class__(header + buffer.getvalue())
    else:
        header = bytes(first[Ether])[:34]
        return first[Ether].__class__(header + buffer.getvalue())


def reassemble4_ether(listoffragments):
    return reassemble4_core(listoffragments, False)


def reassemble4(listoffragments):
    return reassemble4_core(listoffragments, True)