# GAS tests # Copyright (c) 2013, Qualcomm Atheros, Inc. # Copyright (c) 2013-2015, Jouni Malinen # # This software may be distributed under the terms of the BSD license. # See README for more details. from remotehost import remote_compatible import time import binascii import logging logger = logging.getLogger() import os import re import struct import hostapd from wpasupplicant import WpaSupplicant from tshark import run_tshark from utils import alloc_fail, wait_fail_trigger, skip_with_fips, HwsimSkip from hwsim import HWSimRadio def hs20_ap_params(): params = hostapd.wpa2_params(ssid="test-gas") params['wpa_key_mgmt'] = "WPA-EAP" params['ieee80211w'] = "1" params['ieee8021x'] = "1" params['auth_server_addr'] = "127.0.0.1" params['auth_server_port'] = "1812" params['auth_server_shared_secret'] = "radius" params['interworking'] = "1" params['access_network_type'] = "14" params['internet'] = "1" params['asra'] = "0" params['esr'] = "0" params['uesa'] = "0" params['venue_group'] = "7" params['venue_type'] = "1" params['venue_name'] = [ "eng:Example venue", "fin:Esimerkkipaikka" ] params['roaming_consortium'] = [ "112233", "1020304050", "010203040506", "fedcba" ] params['domain_name'] = "example.com,another.example.com" params['nai_realm'] = [ "0,example.com,13[5:6],21[2:4][5:7]", "0,another.example.com" ] params['anqp_3gpp_cell_net'] = "244,91" params['network_auth_type'] = "02http://www.example.com/redirect/me/here/" params['ipaddr_type_availability'] = "14" params['hs20'] = "1" params['hs20_oper_friendly_name'] = [ "eng:Example operator", "fin:Esimerkkioperaattori" ] params['hs20_wan_metrics'] = "01:8000:1000:80:240:3000" params['hs20_conn_capab'] = [ "1:0:2", "6:22:1", "17:5060:0" ] params['hs20_operating_class'] = "5173" return params def start_ap(ap): params = hs20_ap_params() params['hessid'] = ap['bssid'] return hostapd.add_ap(ap, params) def get_gas_response(dev, bssid, info, allow_fetch_failure=False, extra_test=False): exp = r'<.>(GAS-RESPONSE-INFO) addr=([0-9a-f:]*) dialog_token=([0-9]*) status_code=([0-9]*) resp_len=([\-0-9]*)' res = re.split(exp, info) if len(res) < 6: raise Exception("Could not parse GAS-RESPONSE-INFO") if res[2] != bssid: raise Exception("Unexpected BSSID in response") token = res[3] status = res[4] if status != "0": raise Exception("GAS query failed") resp_len = res[5] if resp_len == "-1": raise Exception("GAS query reported invalid response length") if int(resp_len) > 2000: raise Exception("Unexpected long GAS response") if extra_test: if "FAIL" not in dev.request("GAS_RESPONSE_GET " + bssid + " 123456"): raise Exception("Invalid dialog token accepted") if "FAIL-Invalid range" not in dev.request("GAS_RESPONSE_GET " + bssid + " " + token + " 10000,10001"): raise Exception("Invalid range accepted") if "FAIL-Invalid range" not in dev.request("GAS_RESPONSE_GET " + bssid + " " + token + " 0,10000"): raise Exception("Invalid range accepted") if "FAIL" not in dev.request("GAS_RESPONSE_GET " + bssid + " " + token + " 0"): raise Exception("Invalid GAS_RESPONSE_GET accepted") res1_2 = dev.request("GAS_RESPONSE_GET " + bssid + " " + token + " 1,2") res5_3 = dev.request("GAS_RESPONSE_GET " + bssid + " " + token + " 5,3") resp = dev.request("GAS_RESPONSE_GET " + bssid + " " + token) if "FAIL" in resp: if allow_fetch_failure: logger.debug("GAS response was not available anymore") return raise Exception("Could not fetch GAS response") if len(resp) != int(resp_len) * 2: raise Exception("Unexpected GAS response length") logger.debug("GAS response: " + resp) if extra_test: if resp[2:6] != res1_2: raise Exception("Unexpected response substring res1_2: " + res1_2) if resp[10:16] != res5_3: raise Exception("Unexpected response substring res5_3: " + res5_3) def test_gas_generic(dev, apdev): """Generic GAS query""" bssid = apdev[0]['bssid'] params = hs20_ap_params() params['hessid'] = bssid hostapd.add_ap(apdev[0], params) cmds = [ "foo", "00:11:22:33:44:55", "00:11:22:33:44:55 ", "00:11:22:33:44:55 ", "00:11:22:33:44:55 1", "00:11:22:33:44:55 1 1234", "00:11:22:33:44:55 qq", "00:11:22:33:44:55 qq 1234", "00:11:22:33:44:55 00 1", "00:11:22:33:44:55 00 123", "00:11:22:33:44:55 00 ", "00:11:22:33:44:55 00 qq" ] for cmd in cmds: if "FAIL" not in dev[0].request("GAS_REQUEST " + cmd): raise Exception("Invalid GAS_REQUEST accepted: " + cmd) dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101") if "FAIL" in req: raise Exception("GAS query request rejected") ev = dev[0].wait_event(["GAS-RESPONSE-INFO"], timeout=10) if ev is None: raise Exception("GAS query timed out") get_gas_response(dev[0], bssid, ev, extra_test=True) if "FAIL" not in dev[0].request("GAS_RESPONSE_GET ff"): raise Exception("Invalid GAS_RESPONSE_GET accepted") def test_gas_rand_ta(dev, apdev, params): """Generic GAS query with random TA""" flags = int(dev[0].get_driver_status_field('capa.flags'), 16) if flags & 0x0000400000000000 == 0: raise HwsimSkip("Driver does not support random GAS TA") try: _test_gas_rand_ta(dev, apdev, params['logdir']) finally: dev[0].request("SET gas_rand_mac_addr 0") def _test_gas_rand_ta(dev, apdev, logdir): bssid = apdev[0]['bssid'] params = hs20_ap_params() params['hessid'] = bssid hostapd.add_ap(apdev[0], params) dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) req = dev[0].request("SET gas_rand_mac_addr 1") if "FAIL" in req: raise Exception("Failed to set gas_rand_mac_addr") dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101") if "FAIL" in req: raise Exception("GAS query request rejected") ev = dev[0].wait_event(["GAS-RESPONSE-INFO"], timeout=10) if ev is None: raise Exception("GAS query timed out") get_gas_response(dev[0], bssid, ev, extra_test=True) out = run_tshark(os.path.join(logdir, "hwsim0.pcapng"), "wlan_mgt.fixed.category_code == 4 && (wlan_mgt.fixed.publicact == 0x0a || wlan_mgt.fixed.publicact == 0x0b)", display=["wlan.ta", "wlan.ra"]) res = out.splitlines() if len(res) != 2: raise Exception("Unexpected number of GAS frames") req_ta = res[0].split('\t')[0] resp_ra = res[1].split('\t')[1] logger.info("Request TA: %s, Response RA: %s" % (req_ta, resp_ra)) if req_ta != resp_ra: raise Exception("Request TA does not match response RA") if req_ta == dev[0].own_addr(): raise Exception("Request TA was own permanent MAC address, not random") def test_gas_concurrent_scan(dev, apdev): """Generic GAS queries with concurrent scan operation""" bssid = apdev[0]['bssid'] params = hs20_ap_params() params['hessid'] = bssid hostapd.add_ap(apdev[0], params) # get BSS entry available to allow GAS query dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) logger.info("Request concurrent operations") req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101") if "FAIL" in req: raise Exception("GAS query request rejected") req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000801") if "FAIL" in req: raise Exception("GAS query request rejected") dev[0].scan(no_wait=True) req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000201") if "FAIL" in req: raise Exception("GAS query request rejected") req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000501") if "FAIL" in req: raise Exception("GAS query request rejected") responses = 0 for i in range(0, 5): ev = dev[0].wait_event(["GAS-RESPONSE-INFO", "CTRL-EVENT-SCAN-RESULTS"], timeout=10) if ev is None: raise Exception("Operation timed out") if "GAS-RESPONSE-INFO" in ev: responses = responses + 1 get_gas_response(dev[0], bssid, ev, allow_fetch_failure=True) if responses != 4: raise Exception("Unexpected number of GAS responses") def test_gas_concurrent_connect(dev, apdev): """Generic GAS queries with concurrent connection operation""" skip_with_fips(dev[0]) bssid = apdev[0]['bssid'] params = hs20_ap_params() params['hessid'] = bssid hostapd.add_ap(apdev[0], params) dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) logger.debug("Start concurrent connect and GAS request") dev[0].connect("test-gas", key_mgmt="WPA-EAP", eap="TTLS", identity="DOMAIN\mschapv2 user", anonymous_identity="ttls", password="password", phase2="auth=MSCHAPV2", ca_cert="auth_serv/ca.pem", wait_connect=False, scan_freq="2412") req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101") if "FAIL" in req: raise Exception("GAS query request rejected") ev = dev[0].wait_event(["CTRL-EVENT-CONNECTED", "GAS-RESPONSE-INFO"], timeout=20) if ev is None: raise Exception("Operation timed out") if "CTRL-EVENT-CONNECTED" not in ev: raise Exception("Unexpected operation order") ev = dev[0].wait_event(["CTRL-EVENT-CONNECTED", "GAS-RESPONSE-INFO"], timeout=20) if ev is None: raise Exception("Operation timed out") if "GAS-RESPONSE-INFO" not in ev: raise Exception("Unexpected operation order") get_gas_response(dev[0], bssid, ev) dev[0].request("DISCONNECT") dev[0].wait_disconnected(timeout=5) logger.debug("Wait six seconds for expiration of connect-without-scan") time.sleep(6) dev[0].dump_monitor() logger.debug("Start concurrent GAS request and connect") req = dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101") if "FAIL" in req: raise Exception("GAS query request rejected") dev[0].request("RECONNECT") ev = dev[0].wait_event(["GAS-RESPONSE-INFO"], timeout=10) if ev is None: raise Exception("Operation timed out") get_gas_response(dev[0], bssid, ev) ev = dev[0].wait_event(["CTRL-EVENT-SCAN-RESULTS"], timeout=20) if ev is None: raise Exception("No new scan results reported") ev = dev[0].wait_connected(timeout=20, error="Operation tiemd out") if "CTRL-EVENT-CONNECTED" not in ev: raise Exception("Unexpected operation order") def gas_fragment_and_comeback(dev, apdev, frag_limit=0, comeback_delay=0): hapd = start_ap(apdev) if frag_limit: hapd.set("gas_frag_limit", str(frag_limit)) if comeback_delay: hapd.set("gas_comeback_delay", str(comeback_delay)) dev.scan_for_bss(apdev['bssid'], freq="2412", force_scan=True) dev.request("FETCH_ANQP") ev = dev.wait_event(["GAS-QUERY-DONE"], timeout=5) if ev is None: raise Exception("No GAS-QUERY-DONE event") if "result=SUCCESS" not in ev: raise Exception("Unexpected GAS result: " + ev) for i in range(0, 13): ev = dev.wait_event(["RX-ANQP", "RX-HS20-ANQP"], timeout=5) if ev is None: raise Exception("Operation timed out") ev = dev.wait_event(["ANQP-QUERY-DONE"], timeout=1) if ev is None: raise Exception("No ANQP-QUERY-DONE event") if "result=SUCCESS" not in ev: raise Exception("Unexpected ANQP result: " + ev) def test_gas_fragment(dev, apdev): """GAS fragmentation""" gas_fragment_and_comeback(dev[0], apdev[0], frag_limit=50) def test_gas_fragment_mcc(dev, apdev): """GAS fragmentation with mac80211_hwsim MCC enabled""" with HWSimRadio(n_channels=2) as (radio, iface): wpas = WpaSupplicant(global_iface='/tmp/wpas-wlan5') wpas.interface_add(iface) gas_fragment_and_comeback(wpas, apdev[0], frag_limit=50) def test_gas_fragment_with_comeback_delay(dev, apdev): """GAS fragmentation and comeback delay""" gas_fragment_and_comeback(dev[0], apdev[0], frag_limit=50, comeback_delay=500) def test_gas_fragment_with_comeback_delay_mcc(dev, apdev): """GAS fragmentation and comeback delay with mac80211_hwsim MCC enabled""" with HWSimRadio(n_channels=2) as (radio, iface): wpas = WpaSupplicant(global_iface='/tmp/wpas-wlan5') wpas.interface_add(iface) gas_fragment_and_comeback(wpas, apdev[0], frag_limit=50, comeback_delay=500) def test_gas_comeback_delay(dev, apdev): """GAS comeback delay""" run_gas_comeback_delay(dev, apdev, 500) def test_gas_comeback_delay_long(dev, apdev): """GAS long comeback delay""" run_gas_comeback_delay(dev, apdev, 2500) def test_gas_comeback_delay_long2(dev, apdev): """GAS long comeback delay over default STA timeout""" run_gas_comeback_delay(dev, apdev, 6000) def run_gas_comeback_delay(dev, apdev, delay): hapd = start_ap(apdev[0]) hapd.set("gas_comeback_delay", str(delay)) dev[0].scan_for_bss(apdev[0]['bssid'], freq="2412", force_scan=True) dev[0].request("FETCH_ANQP") if "FAIL-BUSY" not in dev[0].request("SCAN"): raise Exception("SCAN accepted during FETCH_ANQP") for i in range(0, 6): ev = dev[0].wait_event(["RX-ANQP"], timeout=10) if ev is None: raise Exception("Operation timed out") @remote_compatible def test_gas_stop_fetch_anqp(dev, apdev): """Stop FETCH_ANQP operation""" hapd = start_ap(apdev[0]) dev[0].scan_for_bss(apdev[0]['bssid'], freq="2412", force_scan=True) hapd.set("ext_mgmt_frame_handling", "1") dev[0].request("FETCH_ANQP") dev[0].request("STOP_FETCH_ANQP") hapd.set("ext_mgmt_frame_handling", "0") ev = dev[0].wait_event(["RX-ANQP", "GAS-QUERY-DONE"], timeout=10) if ev is None: raise Exception("GAS-QUERY-DONE timed out") if "RX-ANQP" in ev: raise Exception("Unexpected ANQP response received") def test_gas_anqp_get(dev, apdev): """GAS/ANQP query for both IEEE 802.11 and Hotspot 2.0 elements""" hapd = start_ap(apdev[0]) bssid = apdev[0]['bssid'] dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) if "OK" not in dev[0].request("ANQP_GET " + bssid + " 258,268,hs20:3,hs20:4"): raise Exception("ANQP_GET command failed") ev = dev[0].wait_event(["GAS-QUERY-START"], timeout=5) if ev is None: raise Exception("GAS query start timed out") ev = dev[0].wait_event(["GAS-QUERY-DONE"], timeout=10) if ev is None: raise Exception("GAS query timed out") ev = dev[0].wait_event(["RX-ANQP"], timeout=1) if ev is None or "Venue Name" not in ev: raise Exception("Did not receive Venue Name") ev = dev[0].wait_event(["RX-ANQP"], timeout=1) if ev is None or "Domain Name list" not in ev: raise Exception("Did not receive Domain Name list") ev = dev[0].wait_event(["RX-HS20-ANQP"], timeout=1) if ev is None or "Operator Friendly Name" not in ev: raise Exception("Did not receive Operator Friendly Name") ev = dev[0].wait_event(["RX-HS20-ANQP"], timeout=1) if ev is None or "WAN Metrics" not in ev: raise Exception("Did not receive WAN Metrics") ev = dev[0].wait_event(["ANQP-QUERY-DONE"], timeout=10) if ev is None: raise Exception("ANQP-QUERY-DONE event not seen") if "result=SUCCESS" not in ev: raise Exception("Unexpected result: " + ev) if "OK" not in dev[0].request("ANQP_GET " + bssid + " hs20:3"): raise Exception("ANQP_GET command failed") ev = dev[0].wait_event(["GAS-QUERY-START"], timeout=5) if ev is None: raise Exception("GAS query start timed out") ev = dev[0].wait_event(["GAS-QUERY-DONE"], timeout=10) if ev is None: raise Exception("GAS query timed out") ev = dev[0].wait_event(["RX-HS20-ANQP"], timeout=1) if ev is None or "Operator Friendly Name" not in ev: raise Exception("Did not receive Operator Friendly Name") ev = dev[0].wait_event(["ANQP-QUERY-DONE"], timeout=10) if ev is None: raise Exception("ANQP-QUERY-DONE event not seen") if "result=SUCCESS" not in ev: raise Exception("Unexpected result: " + ev) if "OK" not in dev[0].request("HS20_ANQP_GET " + bssid + " 3,4"): raise Exception("ANQP_GET command failed") ev = dev[0].wait_event(["RX-HS20-ANQP"], timeout=1) if ev is None or "Operator Friendly Name" not in ev: raise Exception("Did not receive Operator Friendly Name") ev = dev[0].wait_event(["RX-HS20-ANQP"], timeout=1) if ev is None or "WAN Metrics" not in ev: raise Exception("Did not receive WAN Metrics") logger.info("Attempt an MBO request with an AP that does not support MBO") if "OK" not in dev[0].request("ANQP_GET " + bssid + " 272,mbo:2"): raise Exception("ANQP_GET command failed (2)") ev = dev[0].wait_event(["GAS-QUERY-START"], timeout=5) if ev is None: raise Exception("GAS query start timed out (2)") ev = dev[0].wait_event(["GAS-QUERY-DONE"], timeout=10) if ev is None: raise Exception("GAS query timed out (2)") cmds = [ "", "foo", "00:11:22:33:44:55 258,hs20:-1", "00:11:22:33:44:55 258,hs20:0", "00:11:22:33:44:55 258,hs20:32", "00:11:22:33:44:55 hs20:-1", "00:11:22:33:44:55 hs20:0", "00:11:22:33:44:55 hs20:32", "00:11:22:33:44:55 mbo:-1", "00:11:22:33:44:55 mbo:0", "00:11:22:33:44:55 mbo:999", "00:11:22:33:44:55 mbo:1,258,mbo:2,mbo:3,259", "00:11:22:33:44:55", "00:11:22:33:44:55 ", "00:11:22:33:44:55 0", "00:11:22:33:44:55 1" ] for cmd in cmds: if "FAIL" not in dev[0].request("ANQP_GET " + cmd): raise Exception("Invalid ANQP_GET accepted") cmds = [ "", "foo", "00:11:22:33:44:55 -1", "00:11:22:33:44:55 0", "00:11:22:33:44:55 32", "00:11:22:33:44:55", "00:11:22:33:44:55 ", "00:11:22:33:44:55 0", "00:11:22:33:44:55 1" ] for cmd in cmds: if "FAIL" not in dev[0].request("HS20_ANQP_GET " + cmd): raise Exception("Invalid HS20_ANQP_GET accepted") def test_gas_anqp_get_oom(dev, apdev): """GAS/ANQP query OOM""" hapd = start_ap(apdev[0]) bssid = apdev[0]['bssid'] dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) with alloc_fail(dev[0], 1, "wpabuf_alloc;anqp_send_req"): if "FAIL" not in dev[0].request("ANQP_GET " + bssid + " 258,268,hs20:3,hs20:4"): raise Exception("ANQP_GET command accepted during OOM") with alloc_fail(dev[0], 1, "hs20_build_anqp_req;hs20_anqp_send_req"): if "FAIL" not in dev[0].request("HS20_ANQP_GET " + bssid + " 1"): raise Exception("HS20_ANQP_GET command accepted during OOM") with alloc_fail(dev[0], 1, "gas_query_req;hs20_anqp_send_req"): if "FAIL" not in dev[0].request("HS20_ANQP_GET " + bssid + " 1"): raise Exception("HS20_ANQP_GET command accepted during OOM") with alloc_fail(dev[0], 1, "=hs20_anqp_send_req"): if "FAIL" not in dev[0].request("REQ_HS20_ICON " + bssid + " w1fi_logo"): raise Exception("REQ_HS20_ICON command accepted during OOM") with alloc_fail(dev[0], 2, "=hs20_anqp_send_req"): if "FAIL" not in dev[0].request("REQ_HS20_ICON " + bssid + " w1fi_logo"): raise Exception("REQ_HS20_ICON command accepted during OOM") def test_gas_anqp_icon_binary_proto(dev, apdev): """GAS/ANQP and icon binary protocol testing""" hapd = start_ap(apdev[0]) bssid = apdev[0]['bssid'] dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) hapd.set("ext_mgmt_frame_handling", "1") tests = [ '010000', '01000000', '00000000', '00030000', '00020000', '00000100', '0001ff0100ee', '0001ff0200ee' ] for test in tests: dev[0].request("HS20_ICON_REQUEST " + bssid + " w1fi_logo") query = gas_rx(hapd) gas = parse_gas(query['payload']) resp = action_response(query) data = binascii.unhexlify(test) data = binascii.unhexlify('506f9a110b00') + data data = struct.pack('(GAS-RESPONSE-INFO) addr=([0-9a-f:]*) dialog_token=([0-9]*) status_code=([0-9]*) resp_len=([\-0-9]*)' res = re.split(exp, ev) if len(res) < 6: raise Exception("Could not parse GAS-RESPONSE-INFO") if res[2] != bssid: raise Exception("Unexpected BSSID in response") status = res[4] if status != "59": raise Exception("Unexpected GAS-RESPONSE-INFO status") def test_gas_request_oom(dev, apdev): """GAS_REQUEST OOM""" bssid = apdev[0]['bssid'] params = hs20_ap_params() params['hessid'] = bssid hostapd.add_ap(apdev[0], params) dev[0].scan_for_bss(bssid, freq="2412", force_scan=True) with alloc_fail(dev[0], 1, "gas_build_req;gas_send_request"): if "FAIL" not in dev[0].request("GAS_REQUEST " + bssid + " 42"): raise Exception("GAS query request rejected") with alloc_fail(dev[0], 1, "gas_query_req;gas_send_request"): if "FAIL" not in dev[0].request("GAS_REQUEST " + bssid + " 42"): raise Exception("GAS query request rejected") with alloc_fail(dev[0], 1, "wpabuf_dup;gas_resp_cb"): if "OK" not in dev[0].request("GAS_REQUEST " + bssid + " 00 000102000101"): raise Exception("GAS query request rejected") ev = dev[0].wait_event(["GAS-RESPONSE-INFO"], timeout=10) if ev is None: raise Exception("No GAS response") if "status_code=0" not in ev: raise Exception("GAS response indicated a failure") def test_gas_max_pending(dev, apdev): """GAS and maximum pending query limit""" hapd = start_ap(apdev[0]) hapd.set("gas_frag_limit", "50") bssid = apdev[0]['bssid'] wpas = WpaSupplicant(global_iface='/tmp/wpas-wlan5') wpas.interface_add("wlan5") if "OK" not in wpas.request("P2P_SET listen_channel 1"): raise Exception("Failed to set listen channel") if "OK" not in wpas.p2p_listen(): raise Exception("Failed to start listen state") if "FAIL" in wpas.request("SET ext_mgmt_frame_handling 1"): raise Exception("Failed to enable external management frame handling") anqp_query = struct.pack(' 8 and status_code == 0: raise Exception("Unexpected success status code {} for dialog token {}".format(status_code, dialog_token)) def test_gas_no_pending(dev, apdev): """GAS and no pending query for comeback request""" hapd = start_ap(apdev[0]) bssid = apdev[0]['bssid'] wpas = WpaSupplicant(global_iface='/tmp/wpas-wlan5') wpas.interface_add("wlan5") if "OK" not in wpas.request("P2P_SET listen_channel 1"): raise Exception("Failed to set listen channel") if "OK" not in wpas.p2p_listen(): raise Exception("Failed to start listen state") if "FAIL" in wpas.request("SET ext_mgmt_frame_handling 1"): raise Exception("Failed to enable external management frame handling") msg = struct.pack('= 4: id_bin = binascii.unhexlify(val[0:4]) id = struct.unpack('