def receive_one_ping(sock: socket, icmp_id: int, seq: int, timeout: int) -> float or None:
"""Receives the ping from the socket.
IP Header (bits): version (8), type of service (8), length (16), id (16), flags (16), time to live (8), protocol (8), checksum (16), source ip (32), destination ip (32).
ICMP Packet (bytes): IP Header (20), ICMP Header (8), ICMP Payload (*).
Ping Wikipedia: https://en.wikipedia.org/wiki/Ping_(networking_utility)
ToS (Type of Service) in IP header for ICMP is 0. Protocol in IP header for ICMP is 1.
Args:
sock: The same socket used for send the ping.
icmp_id: ICMP packet id. Sent packet id should be identical with received packet id.
seq: ICMP packet sequence. Sent packet sequence should be identical with received packet sequence.
timeout: Timeout in seconds.
Returns:
The delay in seconds or None on timeout.
Raises:
TimeToLiveExpired: If the Time-To-Live in IP Header is not large enough for destination.
TimeExceeded: If time exceeded but Time-To-Live does not expired.
"""
ip_header_slice = slice(0, struct.calcsize(IP_HEADER_FORMAT)) # [0:20]
icmp_header_slice = slice(ip_header_slice.stop, ip_header_slice.stop + struct.calcsize(ICMP_HEADER_FORMAT)) # [20:28]
ip_header_keys = ('version', 'tos', 'len', 'id', 'flags', 'ttl', 'protocol', 'checksum', 'src_addr', 'dest_addr')
icmp_header_keys = ('type', 'code', 'checksum', 'id', 'seq')
while True:
selected = select.select([sock], [], [], timeout)
if selected[0] == []: # Timeout
raise errors.Timeout(timeout)
time_recv = time.time()
recv_data, addr = sock.recvfrom(1024)
ip_header_raw, icmp_header_raw, icmp_payload_raw = recv_data[ip_header_slice], recv_data[icmp_header_slice], recv_data[icmp_header_slice.stop:]
ip_header = dict(zip(ip_header_keys, struct.unpack(IP_HEADER_FORMAT, ip_header_raw)))
_debug("IP HEADER:", ip_header)
icmp_header = dict(zip(icmp_header_keys, struct.unpack(ICMP_HEADER_FORMAT, icmp_header_raw)))
_debug("ICMP HEADER:", icmp_header)
if icmp_header['type'] == IcmpType.TIME_EXCEEDED: # TIME_EXCEEDED has no icmp_id and icmp_seq. Usually they are 0.
if icmp_header['code'] == IcmpTimeExceededCode.TTL_EXPIRED:
raise errors.TimeToLiveExpired() # Some router does not report TTL expired and then timeout shows.
raise errors.TimeExceeded()
if icmp_header['id'] == icmp_id and icmp_header['seq'] == seq: # ECHO_REPLY should match the
if icmp_header['type'] == IcmpType.ECHO_REQUEST: # filters out the ECHO_REQUEST itself.
_debug("ECHO_REQUEST filtered out.")
continue
if icmp_header['type'] == IcmpType.ECHO_REPLY:
time_sent = struct.unpack(ICMP_TIME_FORMAT, icmp_payload_raw[0:struct.calcsize(ICMP_TIME_FORMAT)])[0]
return time_recv - time_sent
def receive_one_ping(sock: socket, icmp_id: int, seq: int,
timeout: int) -> float or None:
"""Receives the ping from the socket.
IP Header (bits): version (8), type of service (8), length (16), id (16), flags (16), time to live (8), protocol (8), checksum (16), source ip (32), destination ip (32).
ICMP Packet (bytes): IP Header (20), ICMP Header (8), ICMP Payload (*).
Ping Wikipedia: https://en.wikipedia.org/wiki/Ping_(networking_utility)
ToS (Type of Service) in IP header for ICMP is 0. Protocol in IP header for ICMP is 1.
Args:
sock: The same socket used for send the ping.
icmp_id: ICMP packet id. Sent packet id should be identical with received packet id.
seq: ICMP packet sequence. Sent packet sequence should be identical with received packet sequence.
timeout: Timeout in seconds.
Returns:
The delay in seconds or None on timeout.
Raises:
TimeToLiveExpired: If the Time-To-Live in IP Header is not large enough for destination.
TimeExceeded: If time exceeded but Time-To-Live does not expired.
DestinationHostUnreachable: If the destination host is unreachable.
DestinationUnreachable: If the destination is unreachable.
"""
ip_header_slice = slice(0, struct.calcsize(IP_HEADER_FORMAT)) # [0:20]
icmp_header_slice = slice(ip_header_slice.stop, ip_header_slice.stop +
struct.calcsize(ICMP_HEADER_FORMAT)) # [20:28]
timeout_time = time.time() + timeout # Exactly time when timeout.
_debug("Timeout time:", time.ctime(timeout_time))
while True:
timeout_left = timeout_time - time.time(
) # How many seconds left until timeout.
timeout_left = timeout_left if timeout_left > 0 else 0 # Timeout must be non-negative
_debug("Timeout left: {:.2f}s".format(timeout_left))
selected = select.select(
[
sock,
], [], [],
timeout_left) # Wait until sock is ready to read or time is out.
if selected[0] == []: # Timeout
raise errors.Timeout(timeout)
time_recv = time.time()
recv_data, addr = sock.recvfrom(1024)
ip_header_raw, icmp_header_raw, icmp_payload_raw = recv_data[
ip_header_slice], recv_data[icmp_header_slice], recv_data[
icmp_header_slice.stop:]
ip_header = read_ip_header(ip_header_raw)
_debug("Received IP Header:", ip_header)
icmp_header = read_icmp_header(icmp_header_raw)
_debug("Received ICMP Header:", icmp_header)
_debug("Received ICMP Payload:", icmp_payload_raw)
if icmp_header['id'] and icmp_header[
'id'] != icmp_id: # ECHO_REPLY should match the ID field.
_debug("ICMP ID dismatch. Packet filtered out.")
continue
if icmp_header[
'type'] == IcmpType.TIME_EXCEEDED: # TIME_EXCEEDED has no icmp_id and icmp_seq. Usually they are 0.
if icmp_header['code'] == IcmpTimeExceededCode.TTL_EXPIRED:
raise errors.TimeToLiveExpired(
) # Some router does not report TTL expired and then timeout shows.
raise errors.TimeExceeded()
if icmp_header[
'type'] == IcmpType.DESTINATION_UNREACHABLE: # DESTINATION_UNREACHABLE has no icmp_id and icmp_seq. Usually they are 0.
if icmp_header[
'code'] == IcmpDestinationUnreachableCode.DESTINATION_HOST_UNREACHABLE:
raise errors.DestinationHostUnreachable()
raise errors.DestinationUnreachable()
if icmp_header['id'] and icmp_header[
'seq'] == seq: # ECHO_REPLY should match the SEQ field.
if icmp_header[
'type'] == IcmpType.ECHO_REQUEST: # filters out the ECHO_REQUEST itself.
_debug("ECHO_REQUEST received. Packet filtered out.")
continue
if icmp_header['type'] == IcmpType.ECHO_REPLY:
time_sent = struct.unpack(
ICMP_TIME_FORMAT,
icmp_payload_raw[0:struct.calcsize(ICMP_TIME_FORMAT)])[0]
return time_recv - time_sent
_debug("Uncatched ICMP Packet:", icmp_header)
