test/vpp_pg_interface.py

   1 import os
   2 import time
   3 import socket
   4 import struct
   5 from traceback import format_exc, format_stack
   6
   7 import scapy.compat
   8 from scapy.utils import wrpcap, rdpcap, PcapReader
   9 from scapy.plist import PacketList
  10 from vpp_interface import VppInterface
  11
  12 from scapy.layers.l2 import Ether, ARP
  13 from scapy.layers.inet6 import IPv6, ICMPv6ND_NS, ICMPv6ND_NA,\
  14     ICMPv6NDOptSrcLLAddr, ICMPv6NDOptDstLLAddr, ICMPv6ND_RA, RouterAlert, \
  15     IPv6ExtHdrHopByHop
  16 from util import ppp, ppc
  17 from scapy.utils6 import in6_getnsma, in6_getnsmac, in6_ismaddr
  18 from scapy.utils import inet_pton, inet_ntop
  19
  20
  21 class CaptureTimeoutError(Exception):
  22     """ Exception raised if capture or packet doesn't appear within timeout """
  23     pass
  24
  25
  26 def is_ipv6_misc(p):
  27     """ Is packet one of uninteresting IPv6 broadcasts? """
  28     if p.haslayer(ICMPv6ND_RA):
  29         if in6_ismaddr(p[IPv6].dst):
  30             return True
  31     if p.haslayer(IPv6ExtHdrHopByHop):
  32         for o in p[IPv6ExtHdrHopByHop].options:
  33             if isinstance(o, RouterAlert):
  34                 return True
  35     return False
  36
  37
  38 class VppPGInterface(VppInterface):
  39     """
  40     VPP packet-generator interface
  41     """
  42
  43     @property
  44     def pg_index(self):
  45         """packet-generator interface index assigned by VPP"""
  46         return self._pg_index
  47
  48     @property
  49     def out_path(self):
  50         """pcap file path - captured packets"""
  51         return self._out_path
  52
  53     @property
  54     def in_path(self):
  55         """ pcap file path - injected packets"""
  56         return self._in_path
  57
  58     @property
  59     def capture_cli(self):
  60         """CLI string to start capture on this interface"""
  61         return self._capture_cli
  62
  63     @property
  64     def cap_name(self):
  65         """capture name for this interface"""
  66         return self._cap_name
  67
  68     @property
  69     def input_cli(self):
  70         """CLI string to load the injected packets"""
  71         if self._nb_replays is not None:
  72             return "%s limit %d" % (self._input_cli, self._nb_replays)
  73         return self._input_cli
  74
  75     @property
  76     def in_history_counter(self):
  77         """Self-incrementing counter used when renaming old pcap files"""
  78         v = self._in_history_counter
  79         self._in_history_counter += 1
  80         return v
  81
  82     @property
  83     def out_history_counter(self):
  84         """Self-incrementing counter used when renaming old pcap files"""
  85         v = self._out_history_counter
  86         self._out_history_counter += 1
  87         return v
  88
  89     def __init__(self, test, pg_index):
  90         """ Create VPP packet-generator interface """
  91         super(VppPGInterface, self).__init__(test)
  92
  93         r = test.vapi.pg_create_interface(pg_index)
  94         self.set_sw_if_index(r.sw_if_index)
  95
  96         self._in_history_counter = 0
  97         self._out_history_counter = 0
  98         self._out_assert_counter = 0
  99         self._pg_index = pg_index
 100         self._out_file = "pg%u_out.pcap" % self.pg_index
 101         self._out_path = self.test.tempdir + "/" + self._out_file
 102         self._in_file = "pg%u_in.pcap" % self.pg_index
 103         self._in_path = self.test.tempdir + "/" + self._in_file
 104         self._capture_cli = "packet-generator capture pg%u pcap %s" % (
 105             self.pg_index, self.out_path)
 106         self._cap_name = "pcap%u" % self.sw_if_index
 107         self._input_cli = \
 108             "packet-generator new pcap %s source pg%u name %s" % (
 109                 self.in_path, self.pg_index, self.cap_name)
 110         self._nb_replays = None
 111
 112     def _rename_previous_capture_file(self, path, counter, file):
 113         # if a file from a previous capture exists, rename it.
 114         try:
 115             if os.path.isfile(path):
 116                 name = "%s/history.[timestamp:%f].[%s-counter:%04d].%s" % \
 117                     (self.test.tempdir,
 118                      time.time(),
 119                      self.name,
 120                      counter,
 121                      file)
 122                 self.test.logger.debug("Renaming %s->%s" %
 123                                        (path, name))
 124                 os.rename(path, name)
 125         except OSError:
 126             self.test.logger.debug("OSError: Could not rename %s %s" %
 127                                    (path, file))
 128
 129     def enable_capture(self):
 130         """ Enable capture on this packet-generator interface
 131             of at most n packets.
 132             If n < 0, this is no limit
 133         """
 134
 135         self._rename_previous_capture_file(self.out_path,
 136                                            self.out_history_counter,
 137                                            self._out_file)
 138         # FIXME this should be an API, but no such exists atm
 139         self.test.vapi.cli(self.capture_cli)
 140         self._pcap_reader = None
 141
 142     def disable_capture(self):
 143         self.test.vapi.cli("%s disable" % self.capture_cli)
 144
 145     def add_stream(self, pkts, nb_replays=None):
 146         """
 147         Add a stream of packets to this packet-generator
 148
 149         :param pkts: iterable packets
 150
 151         """
 152         self._nb_replays = nb_replays
 153         self._rename_previous_capture_file(self.in_path,
 154                                            self.in_history_counter,
 155                                            self._in_file)
 156         wrpcap(self.in_path, pkts)
 157         self.test.register_capture(self.cap_name)
 158         # FIXME this should be an API, but no such exists atm
 159         self.test.vapi.cli(self.input_cli)
 160
 161     def generate_debug_aid(self, kind):
 162         """ Create a hardlink to the out file with a counter and a file
 163         containing stack trace to ease debugging in case of multiple capture
 164         files present. """
 165         self.test.logger.debug("Generating debug aid for %s on %s" %
 166                                (kind, self._name))
 167         link_path, stack_path = ["%s/debug_%s_%s_%s.%s" %
 168                                  (self.test.tempdir, self._name,
 169                                   self._out_assert_counter, kind, suffix)
 170                                  for suffix in ["pcap", "stack"]
 171                                  ]
 172         os.link(self.out_path, link_path)
 173         with open(stack_path, "w") as f:
 174             f.writelines(format_stack())
 175         self._out_assert_counter += 1
 176
 177     def _get_capture(self, timeout, filter_out_fn=is_ipv6_misc):
 178         """ Helper method to get capture and filter it """
 179         try:
 180             if not self.wait_for_capture_file(timeout):
 181                 return None
 182             output = rdpcap(self.out_path)
 183             self.test.logger.debug("Capture has %s packets" % len(output.res))
 184         except:
 185             self.test.logger.debug("Exception in scapy.rdpcap (%s): %s" %
 186                                    (self.out_path, format_exc()))
 187             return None
 188         before = len(output.res)
 189         if filter_out_fn:
 190             output.res = [p for p in output.res if not filter_out_fn(p)]
 191         removed = before - len(output.res)
 192         if removed:
 193             self.test.logger.debug(
 194                 "Filtered out %s packets from capture (returning %s)" %
 195                 (removed, len(output.res)))
 196         return output
 197
 198     def get_capture(self, expected_count=None, remark=None, timeout=1,
 199                     filter_out_fn=is_ipv6_misc):
 200         """ Get captured packets
 201
 202         :param expected_count: expected number of packets to capture, if None,
 203                                then self.test.packet_count_for_dst_pg_idx is
 204                                used to lookup the expected count
 205         :param remark: remark printed into debug logs
 206         :param timeout: how long to wait for packets
 207         :param filter_out_fn: filter applied to each packet, packets for which
 208                               the filter returns True are removed from capture
 209         :returns: iterable packets
 210         """
 211         remaining_time = timeout
 212         capture = None
 213         name = self.name if remark is None else "%s (%s)" % (self.name, remark)
 214         based_on = "based on provided argument"
 215         if expected_count is None:
 216             expected_count = \
 217                 self.test.get_packet_count_for_if_idx(self.sw_if_index)
 218             based_on = "based on stored packet_infos"
 219             if expected_count == 0:
 220                 raise Exception(
 221                     "Internal error, expected packet count for %s is 0!" %
 222                     name)
 223         self.test.logger.debug("Expecting to capture %s (%s) packets on %s" % (
 224             expected_count, based_on, name))
 225         while remaining_time > 0:
 226             before = time.time()
 227             capture = self._get_capture(remaining_time, filter_out_fn)
 228             elapsed_time = time.time() - before
 229             if capture:
 230                 if len(capture.res) == expected_count:
 231                     # bingo, got the packets we expected
 232                     return capture
 233                 elif len(capture.res) > expected_count:
 234                     self.test.logger.error(
 235                         ppc("Unexpected packets captured:", capture))
 236                     break
 237                 else:
 238                     self.test.logger.debug("Partial capture containing %s "
 239                                            "packets doesn't match expected "
 240                                            "count %s (yet?)" %
 241                                            (len(capture.res), expected_count))
 242             elif expected_count == 0:
 243                 # bingo, got None as we expected - return empty capture
 244                 return PacketList()
 245             remaining_time -= elapsed_time
 246         if capture:
 247             self.generate_debug_aid("count-mismatch")
 248             raise Exception("Captured packets mismatch, captured %s packets, "
 249                             "expected %s packets on %s" %
 250                             (len(capture.res), expected_count, name))
 251         else:
 252             raise Exception("No packets captured on %s" % name)
 253
 254     def assert_nothing_captured(self, remark=None, filter_out_fn=is_ipv6_misc):
 255         """ Assert that nothing unfiltered was captured on interface
 256
 257         :param remark: remark printed into debug logs
 258         :param filter_out_fn: filter applied to each packet, packets for which
 259                               the filter returns True are removed from capture
 260         """
 261         if os.path.isfile(self.out_path):
 262             try:
 263                 capture = self.get_capture(
 264                     0, remark=remark, filter_out_fn=filter_out_fn)
 265                 if not capture or len(capture.res) == 0:
 266                     # junk filtered out, we're good
 267                     return
 268             except:
 269                 pass
 270             self.generate_debug_aid("empty-assert")
 271             if remark:
 272                 raise AssertionError(
 273                     "Non-empty capture file present for interface %s (%s)" %
 274                     (self.name, remark))
 275             else:
 276                 raise AssertionError("Capture file present for interface %s" %
 277                                      self.name)
 278
 279     def wait_for_capture_file(self, timeout=1):
 280         """
 281         Wait until pcap capture file appears
 282
 283         :param timeout: How long to wait for the packet (default 1s)
 284
 285         :returns: True/False if the file is present or appears within timeout
 286         """
 287         deadline = time.time() + timeout
 288         if not os.path.isfile(self.out_path):
 289             self.test.logger.debug("Waiting for capture file %s to appear, "
 290                                    "timeout is %ss" % (self.out_path, timeout))
 291         else:
 292             self.test.logger.debug("Capture file %s already exists" %
 293                                    self.out_path)
 294             return True
 295         while time.time() < deadline:
 296             if os.path.isfile(self.out_path):
 297                 break
 298             self._test.sleep(0)  # yield
 299         if os.path.isfile(self.out_path):
 300             self.test.logger.debug("Capture file appeared after %fs" %
 301                                    (time.time() - (deadline - timeout)))
 302         else:
 303             self.test.logger.debug("Timeout - capture file still nowhere")
 304             return False
 305         return True
 306
 307     def verify_enough_packet_data_in_pcap(self):
 308         """
 309         Check if enough data is available in file handled by internal pcap
 310         reader so that a whole packet can be read.
 311
 312         :returns: True if enough data present, else False
 313         """
 314         orig_pos = self._pcap_reader.f.tell()  # save file position
 315         enough_data = False
 316         # read packet header from pcap
 317         packet_header_size = 16
 318         caplen = None
 319         end_pos = None
 320         hdr = self._pcap_reader.f.read(packet_header_size)
 321         if len(hdr) == packet_header_size:
 322             # parse the capture length - caplen
 323             sec, usec, caplen, wirelen = struct.unpack(
 324                 self._pcap_reader.endian + "IIII", hdr)
 325             self._pcap_reader.f.seek(0, 2)  # seek to end of file
 326             end_pos = self._pcap_reader.f.tell()  # get position at end
 327             if end_pos >= orig_pos + len(hdr) + caplen:
 328                 enough_data = True  # yay, we have enough data
 329         self._pcap_reader.f.seek(orig_pos, 0)  # restore original position
 330         return enough_data
 331
 332     def wait_for_packet(self, timeout, filter_out_fn=is_ipv6_misc):
 333         """
 334         Wait for next packet captured with a timeout
 335
 336         :param timeout: How long to wait for the packet
 337
 338         :returns: Captured packet if no packet arrived within timeout
 339         :raises Exception: if no packet arrives within timeout
 340         """
 341         deadline = time.time() + timeout
 342         if self._pcap_reader is None:
 343             if not self.wait_for_capture_file(timeout):
 344                 raise CaptureTimeoutError("Capture file %s did not appear "
 345                                           "within timeout" % self.out_path)
 346             while time.time() < deadline:
 347                 try:
 348                     self._pcap_reader = PcapReader(self.out_path)
 349                     break
 350                 except:
 351                     self.test.logger.debug(
 352                         "Exception in scapy.PcapReader(%s): %s" %
 353                         (self.out_path, format_exc()))
 354         if not self._pcap_reader:
 355             raise CaptureTimeoutError("Capture file %s did not appear within "
 356                                       "timeout" % self.out_path)
 357
 358         poll = False
 359         if timeout > 0:
 360             self.test.logger.debug("Waiting for packet")
 361         else:
 362             poll = True
 363             self.test.logger.debug("Polling for packet")
 364         while time.time() < deadline or poll:
 365             if not self.verify_enough_packet_data_in_pcap():
 366                 self._test.sleep(0)  # yield
 367                 poll = False
 368                 continue
 369             p = self._pcap_reader.recv()
 370             if p is not None:
 371                 if filter_out_fn is not None and filter_out_fn(p):
 372                     self.test.logger.debug(
 373                         "Packet received after %ss was filtered out" %
 374                         (time.time() - (deadline - timeout)))
 375                 else:
 376                     self.test.logger.debug(
 377                         "Packet received after %fs" %
 378                         (time.time() - (deadline - timeout)))
 379                     return p
 380             self._test.sleep(0)  # yield
 381             poll = False
 382         self.test.logger.debug("Timeout - no packets received")
 383         raise CaptureTimeoutError("Packet didn't arrive within timeout")
 384
 385     def create_arp_req(self):
 386         """Create ARP request applicable for this interface"""
 387         return (Ether(dst="ff:ff:ff:ff:ff:ff", src=self.remote_mac) /
 388                 ARP(op=ARP.who_has, pdst=self.local_ip4,
 389                     psrc=self.remote_ip4, hwsrc=self.remote_mac))
 390
 391     def create_ndp_req(self):
 392         """Create NDP - NS applicable for this interface"""
 393         nsma = in6_getnsma(inet_pton(socket.AF_INET6, self.local_ip6))
 394         d = inet_ntop(socket.AF_INET6, nsma)
 395
 396         return (Ether(dst=in6_getnsmac(nsma)) /
 397                 IPv6(dst=d, src=self.remote_ip6) /
 398                 ICMPv6ND_NS(tgt=self.local_ip6) /
 399                 ICMPv6NDOptSrcLLAddr(lladdr=self.remote_mac))
 400
 401     def resolve_arp(self, pg_interface=None):
 402         """Resolve ARP using provided packet-generator interface
 403
 404         :param pg_interface: interface used to resolve, if None then this
 405             interface is used
 406
 407         """
 408         if pg_interface is None:
 409             pg_interface = self
 410         self.test.logger.info("Sending ARP request for %s on port %s" %
 411                               (self.local_ip4, pg_interface.name))
 412         arp_req = self.create_arp_req()
 413         pg_interface.add_stream(arp_req)
 414         pg_interface.enable_capture()
 415         self.test.pg_start()
 416         self.test.logger.info(self.test.vapi.cli("show trace"))
 417         try:
 418             captured_packet = pg_interface.wait_for_packet(1)
 419         except:
 420             self.test.logger.info("No ARP received on port %s" %
 421                                   pg_interface.name)
 422             return
 423         arp_reply = captured_packet.copy()  # keep original for exception
 424         try:
 425             if arp_reply[ARP].op == ARP.is_at:
 426                 self.test.logger.info("VPP %s MAC address is %s " %
 427                                       (self.name, arp_reply[ARP].hwsrc))
 428                 self._local_mac = arp_reply[ARP].hwsrc
 429             else:
 430                 self.test.logger.info("No ARP received on port %s" %
 431                                       pg_interface.name)
 432         except:
 433             self.test.logger.error(
 434                 ppp("Unexpected response to ARP request:", captured_packet))
 435             raise
 436
 437     def resolve_ndp(self, pg_interface=None, timeout=1):
 438         """Resolve NDP using provided packet-generator interface
 439
 440         :param pg_interface: interface used to resolve, if None then this
 441             interface is used
 442         :param timeout: how long to wait for response before giving up
 443
 444         """
 445         if pg_interface is None:
 446             pg_interface = self
 447         self.test.logger.info("Sending NDP request for %s on port %s" %
 448                               (self.local_ip6, pg_interface.name))
 449         ndp_req = self.create_ndp_req()
 450         pg_interface.add_stream(ndp_req)
 451         pg_interface.enable_capture()
 452         self.test.pg_start()
 453         now = time.time()
 454         deadline = now + timeout
 455         # Enabling IPv6 on an interface can generate more than the
 456         # ND reply we are looking for (namely MLD). So loop through
 457         # the replies to look for want we want.
 458         while now < deadline:
 459             try:
 460                 captured_packet = pg_interface.wait_for_packet(
 461                     deadline - now, filter_out_fn=None)
 462             except:
 463                 self.test.logger.error(
 464                     "Timeout while waiting for NDP response")
 465                 raise
 466             ndp_reply = captured_packet.copy()  # keep original for exception
 467             try:
 468                 ndp_na = ndp_reply[ICMPv6ND_NA]
 469                 opt = ndp_na[ICMPv6NDOptDstLLAddr]
 470                 self.test.logger.info("VPP %s MAC address is %s " %
 471                                       (self.name, opt.lladdr))
 472                 self._local_mac = opt.lladdr
 473                 self.test.logger.debug(self.test.vapi.cli("show trace"))
 474                 # we now have the MAC we've been after
 475                 return
 476             except:
 477                 self.test.logger.info(
 478                     ppp("Unexpected response to NDP request:",
 479                         captured_packet))
 480             now = time.time()
 481
 482         self.test.logger.debug(self.test.vapi.cli("show trace"))
 483         raise Exception("Timeout while waiting for NDP response")