+ 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
+ time.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():
+ time.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
+ time.sleep(0) # yield
+ poll = False
+ self.test.logger.debug("Timeout - no packets received")
+ raise CaptureTimeoutError("Packet didn't arrive within timeout")
+