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