import os import time import socket import struct from traceback import format_exc, format_stack import scapy.compat from scapy.utils import wrpcap, rdpcap, PcapReader from scapy.plist import PacketList from vpp_interface import VppInterface from scapy.layers.l2 import Ether, ARP from scapy.layers.inet6 import IPv6, ICMPv6ND_NS, ICMPv6ND_NA,\ ICMPv6NDOptSrcLLAddr, ICMPv6NDOptDstLLAddr, ICMPv6ND_RA, RouterAlert, \ IPv6ExtHdrHopByHop from util import ppp, ppc from scapy.utils6 import in6_getnsma, in6_getnsmac, in6_ismaddr from scapy.utils import inet_pton, inet_ntop class CaptureTimeoutError(Exception): """ Exception raised if capture or packet doesn't appear within timeout """ pass def is_ipv6_misc(p): """ Is packet one of uninteresting IPv6 broadcasts? """ if p.haslayer(ICMPv6ND_RA): if in6_ismaddr(p[IPv6].dst): return True if p.haslayer(IPv6ExtHdrHopByHop): for o in p[IPv6ExtHdrHopByHop].options: if isinstance(o, RouterAlert): return True return False class VppPGInterface(VppInterface): """ VPP packet-generator interface """ @property def pg_index(self): """packet-generator interface index assigned by VPP""" return self._pg_index @property def out_path(self): """pcap file path - captured packets""" return self._out_path @property def in_path(self): """ pcap file path - injected packets""" return self._in_path @property def capture_cli(self): """CLI string to start capture on this interface""" return self._capture_cli @property def cap_name(self): """capture name for this interface""" return self._cap_name @property def input_cli(self): """CLI string to load the injected packets""" if self._nb_replays is not None: return "%s limit %d" % (self._input_cli, self._nb_replays) return self._input_cli @property def in_history_counter(self): """Self-incrementing counter used when renaming old pcap files""" v = self._in_history_counter self._in_history_counter += 1 return v @property def out_history_counter(self): """Self-incrementing counter used when renaming old pcap files""" v = self._out_history_counter self._out_history_counter += 1 return v def __init__(self, test, pg_index): """ Create VPP packet-generator interface """ super(VppPGInterface, self).__init__(test) r = test.vapi.pg_create_interface(pg_index) self.set_sw_if_index(r.sw_if_index) self._in_history_counter = 0 self._out_history_counter = 0 self._out_assert_counter = 0 self._pg_index = pg_index self._out_file = "pg%u_out.pcap" % self.pg_index self._out_path = self.test.tempdir + "/" + self._out_file self._in_file = "pg%u_in.pcap" % self.pg_index self._in_path = self.test.tempdir + "/" + self._in_file self._capture_cli = "packet-generator capture pg%u pcap %s" % ( self.pg_index, self.out_path) self._cap_name = "pcap%u" % self.sw_if_index self._input_cli = \ "packet-generator new pcap %s source pg%u name %s" % ( self.in_path, self.pg_index, self.cap_name) self._nb_replays = None def enable_capture(self): """ Enable capture on this packet-generator interface of at most n packets. If n < 0, this is no limit """ try: if os.path.isfile(self.out_path): name = "%s/history.[timestamp:%f].[%s-counter:%04d].%s" % \ (self.test.tempdir, time.time(), self.name, self.out_history_counter, self._out_file) self.test.logger.debug("Renaming %s->%s" % (self.out_path, name)) os.rename(self.out_path, name) except: pass # FIXME this should be an API, but no such exists atm self.test.vapi.cli(self.capture_cli) self._pcap_reader = None def disable_capture(self): self.test.vapi.cli("%s disable" % self.capture_cli) def add_stream(self, pkts, nb_replays=None): """ Add a stream of packets to this packet-generator :param pkts: iterable packets """ self._nb_replays = nb_replays try: if os.path.isfile(self.in_path): name = "%s/history.[timestamp:%f].[%s-counter:%04d].%s" %\ (self.test.tempdir, time.time(), self.name, self.in_history_counter, self._in_file) self.test.logger.debug("Renaming %s->%s" % (self.in_path, name)) os.rename(self.in_path, name) except: pass wrpcap(self.in_path, pkts) self.test.register_capture(self.cap_name) # FIXME this should be an API, but no such exists atm self.test.vapi.cli(self.input_cli) def generate_debug_aid(self, kind): """ Create a hardlink to the out file with a counter and a file containing stack trace to ease debugging in case of multiple capture files present. """ self.test.logger.debug("Generating debug aid for %s on %s" % (kind, self._name)) link_path, stack_path = ["%s/debug_%s_%s_%s.%s" % (self.test.tempdir, self._name, self._out_assert_counter, kind, suffix) for suffix in ["pcap", "stack"] ] os.link(self.out_path, link_path) with open(stack_path, "w") as f: f.writelines(format_stack()) self._out_assert_counter += 1 def _get_capture(self, timeout, filter_out_fn=is_ipv6_misc): """ Helper method to get capture and filter it """ try: if not self.wait_for_capture_file(timeout): return None output = rdpcap(self.out_path) self.test.logger.debug("Capture has %s packets" % len(output.res)) except: self.test.logger.debug("Exception in scapy.rdpcap (%s): %s" % (self.out_path, format_exc())) return None before = len(output.res) if filter_out_fn: output.res = [p for p in output.res if not filter_out_fn(p)] removed = before - len(output.res) if removed: self.test.logger.debug( "Filtered out %s packets from capture (returning %s)" % (removed, len(output.res))) return output def get_capture(self, expected_count=None, remark=None, timeout=1, filter_out_fn=is_ipv6_misc): """ Get captured packets :param expected_count: expected number of packets to capture, if None, then self.test.packet_count_for_dst_pg_idx is used to lookup the expected count :param remark: remark printed into debug logs :param timeout: how long to wait for packets :param filter_out_fn: filter applied to each packet, packets for which the filter returns True are removed from capture :returns: iterable packets """ remaining_time = timeout capture = None name = self.name if remark is None else "%s (%s)" % (self.name, remark) based_on = "based on provided argument" if expected_count is None: expected_count = \ self.test.get_packet_count_for_if_idx(self.sw_if_index) based_on = "based on stored packet_infos" if expected_count == 0: raise Exception( "Internal error, expected packet count for %s is 0!" % name) self.test.logger.debug("Expecting to capture %s (%s) packets on %s" % ( expected_count, based_on, name)) while remaining_time > 0: before = time.time() capture = self._get_capture(remaining_time, filter_out_fn) elapsed_time = time.time() - before if capture: if len(capture.res) == expected_count: # bingo, got the packets we expected return capture elif len(capture.res) > expected_count: self.test.logger.error( ppc("Unexpected packets captured:", capture)) break else: self.test.logger.debug("Partial capture containing %s " "packets doesn't match expected " "count %s (yet?)" % (len(capture.res), expected_count)) elif expected_count == 0: # bingo, got None as we expected - return empty capture return PacketList() remaining_time -= elapsed_time if capture: self.generate_debug_aid("count-mismatch") raise Exception("Captured packets mismatch, captured %s packets, " "expected %s packets on %s" % (len(capture.res), expected_count, name)) else: raise Exception("No packets captured on %s" % name) def assert_nothing_captured(self, remark=None, filter_out_fn=is_ipv6_misc): """ Assert that nothing unfiltered was captured on interface :param remark: remark printed into debug logs :param filter_out_fn: filter applied to each packet, packets for which the filter returns True are removed from capture """ if os.path.isfile(self.out_path): try: capture = self.get_capture( 0, remark=remark, filter_out_fn=filter_out_fn) if not capture or len(capture.res) == 0: # junk filtered out, we're good return except: pass self.generate_debug_aid("empty-assert") if remark: raise AssertionError( "Non-empty capture file present for interface %s (%s)" % (self.name, remark)) else: raise AssertionError("Capture file present for interface %s" % self.name) def wait_for_capture_file(self, timeout=1): """ Wait until pcap capture file appears :param timeout: How long to wait for the packet (default 1s) :returns: True/False if the file is present or appears within timeout """ deadline = time.time() + timeout if not os.path.isfile(self.out_path): self.test.logger.debug("Waiting for capture file %s to appear, " "timeout is %ss" % (self.out_path, timeout)) else: self.test.logger.debug("Capture file %s already exists" % self.out_path) return True while time.time() < deadline: if os.path.isfile(self.out_path): break self._test.sleep(0) # yield if os.path.isfile(self.out_path): self.test.logger.debug("Capture file appeared after %fs" % (time.time() - (deadline - timeout))) else: self.test.logger.debug("Timeout - capture file still nowhere") return False return True def verify_enough_packet_data_in_pcap(self): """ Check if enough data is available in file handled by internal pcap reader so that a whole packet can be read. :returns: True if enough data present, else False """ orig_pos = self._pcap_reader.f.tell() # save file position enough_data = False # read packet header from pcap packet_header_size = 16 caplen = None end_pos = None hdr = self._pcap_reader.f.read(packet_header_size) if len(hdr) == packet_header_size: # parse the capture length - caplen sec, usec, caplen, wirelen = struct.unpack( self._pcap_reader.endian + "IIII", hdr) self._pcap_reader.f.seek(0, 2) # seek to end of file end_pos = self._pcap_reader.f.tell() # get position at end if end_pos >= orig_pos + len(hdr) + caplen: enough_data = True # yay, we have enough data self._pcap_reader.f.seek(orig_pos, 0) # restore original position return enough_data def wait_for_packet(self, timeout, filter_out_fn=is_ipv6_misc): """ Wait for next packet captured with a timeout :param timeout: How long to wait for the packet :returns: Captured packet if no packet arrived within timeout :raises Exception: if no packet arrives within timeout """ deadline = time.time() + timeout if self._pcap_reader is None: if not self.wait_for_capture_file(timeout): raise CaptureTimeoutError("Capture file %s did not appear " "within timeout" % self.out_path) while time.time() < deadline: try: self._pcap_reader = PcapReader(self.out_path) break except: self.test.logger.debug( "Exception in scapy.PcapReader(%s): %s" % (self.out_path, format_exc())) if not self._pcap_reader: raise CaptureTimeoutError("Capture file %s did not appear within " "timeout" % self.out_path) poll = False if timeout > 0: self.test.logger.debug("Waiting for packet") else: poll = True self.test.logger.debug("Polling for packet") while time.time() < deadline or poll: if not self.verify_enough_packet_data_in_pcap(): self._test.sleep(0) # yield poll = False continue p = self._pcap_reader.recv() if p is not None: if filter_out_fn is not None and filter_out_fn(p): self.test.logger.debug( "Packet received after %ss was filtered out" % (time.time() - (deadline - timeout))) else: self.test.logger.debug( "Packet received after %fs" % (time.time() - (deadline - timeout))) return p self._test.sleep(0) # yield poll = False self.test.logger.debug("Timeout - no packets received") raise CaptureTimeoutError("Packet didn't arrive within timeout") def create_arp_req(self): """Create ARP request applicable for this interface""" return (Ether(dst="ff:ff:ff:ff:ff:ff", src=self.remote_mac) / ARP(op=ARP.who_has, pdst=self.local_ip4, psrc=self.remote_ip4, hwsrc=self.remote_mac)) def create_ndp_req(self): """Create NDP - NS applicable for this interface""" nsma = in6_getnsma(inet_pton(socket.AF_INET6, self.local_ip6)) d = inet_ntop(socket.AF_INET6, nsma) return (Ether(dst=in6_getnsmac(nsma)) / IPv6(dst=d, src=self.remote_ip6) / ICMPv6ND_NS(tgt=self.local_ip6) / ICMPv6NDOptSrcLLAddr(lladdr=self.remote_mac)) def resolve_arp(self, pg_interface=None): """Resolve ARP using provided packet-generator interface :param pg_interface: interface used to resolve, if None then this interface is used """ if pg_interface is None: pg_interface = self self.test.logger.info("Sending ARP request for %s on port %s" % (self.local_ip4, pg_interface.name)) arp_req = self.create_arp_req() pg_interface.add_stream(arp_req) pg_interface.enable_capture() self.test.pg_start() self.test.logger.info(self.test.vapi.cli("show trace")) try: captured_packet = pg_interface.wait_for_packet(1) except: self.test.logger.info("No ARP received on port %s" % pg_interface.name) return arp_reply = captured_packet.copy() # keep original for exception # Make Dot1AD packet content recognizable to scapy if arp_reply.type == 0x88a8: arp_reply.type = 0x8100 arp_reply = Ether(scapy.compat.raw(arp_reply)) try: if arp_reply[ARP].op == ARP.is_at: self.test.logger.info("VPP %s MAC address is %s " % (self.name, arp_reply[ARP].hwsrc)) self._local_mac = arp_reply[ARP].hwsrc else: self.test.logger.info("No ARP received on port %s" % pg_interface.name) except: self.test.logger.error( ppp("Unexpected response to ARP request:", captured_packet)) raise def resolve_ndp(self, pg_interface=None, timeout=1): """Resolve NDP using provided packet-generator interface :param pg_interface: interface used to resolve, if None then this interface is used :param timeout: how long to wait for response before giving up """ if pg_interface is None: pg_interface = self self.test.logger.info("Sending NDP request for %s on port %s" % (self.local_ip6, pg_interface.name)) ndp_req = self.create_ndp_req() pg_interface.add_stream(ndp_req) pg_interface.enable_capture() self.test.pg_start() now = time.time() deadline = now + timeout # Enabling IPv6 on an interface can generate more than the # ND reply we are looking for (namely MLD). So loop through # the replies to look for want we want. while now < deadline: try: captured_packet = pg_interface.wait_for_packet( deadline - now, filter_out_fn=None) except: self.test.logger.error( "Timeout while waiting for NDP response") raise ndp_reply = captured_packet.copy() # keep original for exception # Make Dot1AD packet content recognizable to scapy if ndp_reply.type == 0x88a8: self._test.logger.info( "Replacing EtherType: 0x88a8 with " "0x8100 and regenerating Ethernet header. ") ndp_reply.type = 0x8100 ndp_reply = Ether(scapy.compat.raw(ndp_reply)) try: ndp_na = ndp_reply[ICMPv6ND_NA] opt = ndp_na[ICMPv6NDOptDstLLAddr] self.test.logger.info("VPP %s MAC address is %s " % (self.name, opt.lladdr)) self._local_mac = opt.lladdr self.test.logger.debug(self.test.vapi.cli("show trace")) # we now have the MAC we've been after return except: self.test.logger.info( ppp("Unexpected response to NDP request:", captured_packet)) now = time.time() self.test.logger.debug(self.test.vapi.cli("show trace")) raise Exception("Timeout while waiting for NDP response")