def wyschc_post(request):
"""HTTP Cloud Function.
Args:
request (flask.Request): The request object.
<http://flask.pocoo.org/docs/1.0/api/#flask.Request>
Returns:
The response text, or any set of values that can be turned into a
Response object using `make_response`
<http://flask.pocoo.org/docs/1.0/api/#flask.Flask.make_response>.
"""
if request.method == 'POST':
# Get request JSON.
print("POST RECEIVED")
request_dict = request.get_json()
print('Received Sigfox message: {}'.format(request_dict))
upload_blob(BUCKET_NAME, zfill("Test", 8), "Test.txt")
return '', 204
else:
print(
'Invalid HTTP Method to invoke Cloud Function. Only POST supported'
)
return abort(405)
def reassemble(request):
if request.method == "POST":
print("[RSMB] The reassembler has been launched.")
# Get request JSON.
request_dict = request.get_json()
print(f'[RSMB] Received HTTP message: {request_dict}')
current_window = int(request_dict["current_window"])
last_index = int(request_dict["last_index"])
header_bytes = int(request_dict["header_bytes"])
# Initialize SCHC variables.
profile_uplink = Sigfox("UPLINK", "ACK ON ERROR", header_bytes)
n = profile_uplink.N
print("[RSMB] Loading fragments")
# Get all the fragments into an array in the format "fragment = [header, payload]"
fragments = []
# For each window, load every fragment into the fragments array
for i in range(current_window + 1):
for j in range(2**n - 1):
print(f"[RSMB] Loading fragment {j}")
fragment_file = read_blob(
BUCKET_NAME, f"all_windows/window_{i}/fragment_{i}_{j}")
print(f"[RSMB] Fragment data: {fragment_file}")
header = fragment_file[:header_bytes]
payload = fragment_file[header_bytes:]
fragment = [header.encode(), payload.encode()]
fragments.append(fragment)
if i == current_window and j == last_index:
break
# Instantiate a Reassembler and start reassembling.
print("[RSMB] Reassembling")
reassembler = Reassembler(profile_uplink, fragments)
payload = bytearray(reassembler.reassemble()).decode("utf-8")
print("[RSMB] Uploading result")
# Upload the full message.
upload_blob(BUCKET_NAME, payload, "PAYLOAD")
try:
_ = requests.post(url=CLEANUP_URL,
json={"header_bytes": header_bytes},
timeout=0.1)
except requests.exceptions.ReadTimeout:
pass
return '', 204
def cleanup(request):
header_bytes = request.get_json()["header_bytes"]
profile = Sigfox("UPLINK", "ACK ON ERROR", header_bytes)
print("[CLN] Deleting timestamp blob")
delete_blob(BUCKET_NAME, "timestamp")
print("[CLN] Resetting SSN")
upload_blob(BUCKET_NAME, "{}", "SSN")
print("[CLN] Initializing fragments...")
delete_blob(BUCKET_NAME, "all_windows/")
initialize_blobs(BUCKET_NAME, profile)
return '', 204
def schc_receiver(request):
"""HTTP Cloud Function.
Args:
request (flask.Request): The request object.
<http://flask.pocoo.org/docs/1.0/api/#flask.Request>
Returns:
The response text, or any set of values that can be turned into a
Response object using `make_response`
<http://flask.pocoo.org/docs/1.0/api/#flask.Flask.make_response>.
"""
if request.method == 'POST':
# Get request JSON.
print("POST RECEIVED")
request_dict = request.get_json()
print('Received Sigfox message: {}'.format(request_dict))
# Get data and Sigfox Sequence Number.
raw_data = request_dict["data"]
sigfox_sequence_number = request_dict["seqNumber"]
ack_req = request_dict["ack"]
header_first_hex = raw_data[:1]
if header_first_hex == '0' or header_first_hex == '1':
header_bytes = 1
elif header_first_hex == '2':
header_bytes = 2
else:
print("Wrong header in raw_data")
return 'wrong header', 204
# Initialize SCHC variables.
profile = Sigfox("UPLINK", "ACK ON ERROR", header_bytes)
n = profile.N
m = profile.M
# If fragment size is greater than buffer size, ignore it and end function.
if len(
raw_data
) / 2 * 8 > profile.UPLINK_MTU: # Fragment is hex, 1 hex = 1/2 byte
return json.dumps(
{"message": "Fragment size is greater than buffer size"}), 200
# If the folder named "all windows" does not exist, create it along with all subdirectories.
initialize_blobs(BUCKET_NAME, profile)
# Compute the fragment compressed number (FCN) from the Profile
fcn_dict = {}
for j in range(2**n - 1):
fcn_dict[zfill(bin((2**n - 2) - (j % (2**n - 1)))[2:], 3)] = j
# Parse raw_data into "data = [header, payload]
# Convert to a Fragment class for easier manipulation.
header = bytes.fromhex(raw_data[:2])
payload = bytearray.fromhex(raw_data[2:])
data = [header, payload]
fragment_message = Fragment(profile, data)
if fragment_message.is_sender_abort():
try:
_ = requests.post(url=CLEANUP_URL,
json={"header_bytes": header_bytes},
timeout=0.1)
except requests.exceptions.ReadTimeout:
pass
return 'Sender-Abort received', 204
# Get data from this fragment.
fcn = fragment_message.header.FCN
rule_id = fragment_message.header.RULE_ID
dtag = fragment_message.header.DTAG
current_window = int(fragment_message.header.W, 2)
# Get the current bitmap.
bitmap = read_blob(
BUCKET_NAME,
f"all_windows/window_{current_window}/bitmap_{current_window}")
# Check if the fragment is an All-1
if is_monochar(fcn) and fcn[0] == '1':
print("[RECV] This is an All-1.")
# Inactivity timer validation
time_received = int(request_dict["time"])
if exists_blob(BUCKET_NAME, "timestamp"):
# Check time validation.
last_time_received = int(read_blob(BUCKET_NAME, "timestamp"))
print(f"[RECV] Previous timestamp: {last_time_received}")
print(f"[RECV] This timestamp: {time_received}")
# If the inactivity timer has been reached, abort communication.
if time_received - last_time_received > profile.INACTIVITY_TIMER_VALUE:
print("[RECV] Inactivity timer reached. Ending session.")
receiver_abort = ReceiverAbort(profile,
fragment_message.header)
print("Sending Receiver Abort")
response_json = send_ack(request_dict, receiver_abort)
print(f"Response content -> {response_json}")
try:
_ = requests.post(url=CLEANUP_URL,
json={"header_bytes": header_bytes},
timeout=0.1)
except requests.exceptions.ReadTimeout:
pass
return response_json, 200
# Update timestamp
upload_blob(BUCKET_NAME, time_received, "timestamp")
# Update bitmap and upload it.
bitmap = replace_bit(bitmap, len(bitmap) - 1, '1')
print(f"Bitmap is now {bitmap}")
upload_blob(
BUCKET_NAME, bitmap,
f"all_windows/window_{current_window}/bitmap_{current_window}")
# Upload the fragment data.
upload_blob(
BUCKET_NAME, data[0].decode("utf-8") + data[1].decode("utf-8"),
f"all_windows/window_{current_window}/fragment_{current_window}_{profile.WINDOW_SIZE - 1}"
)
# Else, it is a normal fragment.
else:
fragment_number = fcn_dict[fragment_message.header.FCN]
position = current_window * profile.WINDOW_SIZE + fragment_number
# Inactivity timer validation
time_received = int(request_dict["time"])
if exists_blob(BUCKET_NAME, "timestamp"):
# Check time validation.
last_time_received = int(read_blob(BUCKET_NAME, "timestamp"))
print(f"[RECV] Previous timestamp: {last_time_received}")
print(f"[RECV] This timestamp: {time_received}")
# If the inactivity timer has been reached, abort communication.
if time_received - last_time_received > profile.INACTIVITY_TIMER_VALUE:
print("[RECV] Inactivity timer reached. Ending session.")
receiver_abort = ReceiverAbort(profile,
fragment_message.header)
print("Sending Receiver Abort")
response_json = send_ack(request_dict, receiver_abort)
print(f"Response content -> {response_json}")
try:
_ = requests.post(url=CLEANUP_URL,
json={"header_bytes": header_bytes},
timeout=0.1)
except requests.exceptions.ReadTimeout:
pass
return response_json, 200
# Update timestamp
upload_blob(BUCKET_NAME, time_received, "timestamp")
# Update Sigfox sequence number JSON
sequence_numbers = json.loads(read_blob(BUCKET_NAME, "SSN"))
sequence_numbers[position] = request_dict["seqNumber"]
print(sequence_numbers)
upload_blob(BUCKET_NAME, json.dumps(sequence_numbers), "SSN")
upload_blob(BUCKET_NAME, fragment_number, "fragment_number")
# Print some data for the user.
print(
f"[RECV] This corresponds to the {str(fragment_number)}th fragment "
f"of the {str(current_window)}th window.")
print(
f"[RECV] Sigfox sequence number: {str(sigfox_sequence_number)}"
)
# Update bitmap and upload it.
bitmap = replace_bit(bitmap, fragment_number, '1')
print(f"Bitmap is now {bitmap}")
upload_blob(
BUCKET_NAME, bitmap,
f"all_windows/window_{current_window}/bitmap_{current_window}")
# Upload the fragment data.
upload_blob(
BUCKET_NAME, data[0].decode("utf-8") + data[1].decode("utf-8"),
f"all_windows/window_{current_window}/fragment_{current_window}_{fragment_number}"
)
# If the fragment requests an ACK...
if ack_req:
# Prepare the ACK bitmap. Find the first bitmap with a 0 in it.
# This bitmap corresponds to the lowest-numered window with losses.
bitmap_ack = None
window_ack = None
for i in range(current_window + 1):
bitmap_ack = read_blob(BUCKET_NAME,
f"all_windows/window_{i}/bitmap_{i}")
print(bitmap_ack)
window_ack = i
if '0' in bitmap_ack:
break
# The final window is only accessible through All-1.
# If All-0, check non-final windows
if fragment_message.is_all_0():
# If the ACK bitmap has a 0 at a non-final window, a fragment has been lost.
if '0' in bitmap_ack:
print(
"[ALL0] Lost fragments have been detected. Preparing ACK."
)
print(f"[ALL0] Bitmap with errors -> {bitmap_ack}")
ack = ACK(profile=profile,
rule_id=rule_id,
dtag=dtag,
w=zfill(format(window_ack, 'b'), m),
c='0',
bitmap=bitmap_ack)
response_json = send_ack(request_dict, ack)
print(f"Response content -> {response_json}")
print("[ALL0] ACK sent.")
return response_json, 200
# If all bitmaps are complete up to this point, no losses are detected.
else:
print("[ALL0] No losses have been detected.")
print("Response content -> ''")
return '', 204
# If the fragment is All-1, the last window should be considered.
if fragment_message.is_all_1():
# First check for 0s in the bitmap. If the bitmap is of a non-final window, send corresponding ACK.
if current_window != window_ack and '0' in bitmap_ack:
print(
"[ALL1] Lost fragments have been detected. Preparing ACK."
)
print(f"[ALL1] Bitmap with errors -> {bitmap_ack}")
ack = ACK(profile=profile,
rule_id=rule_id,
dtag=dtag,
w=zfill(format(window_ack, 'b'), m),
c='0',
bitmap=bitmap_ack)
response_json = send_ack(request_dict, ack)
print(f"Response content -> {response_json}")
print("[ALL1] ACK sent.")
return response_json, 200
# If the bitmap is of the final window, check the following regex.
else:
# The bitmap in the last window follows the following regular expression: "1*0*1*"
# Since the ALL-1, if received, changes the least significant bit of the bitmap.
# For a "complete" bitmap in the last window, there shouldn't be non-consecutive zeroes:
# 1110001 is a valid bitmap, 1101001 is not.
# The bitmap may or may not contain the 0s.
pattern = re.compile("1*0*1")
# If the bitmap matches the regex, check if there are still lost fragments.
if pattern.fullmatch(bitmap_ack) is not None:
# The idea is the following:
# Assume a fragment has been lost, but the regex has been matched.
# For example, we want a bitmap 1111111 but due to a loss we have 1111101.
# This incomplete bitmap matches the regex.
# We should note that here the SSN of the All-1 and the penultimate fragment received
# are not consecutive.
# Retransmitting the lost fragment and resending the All-1 solves that problem.
# There is another problematic case: we want a bitmap 1111111 but due to losses we have 1111001.
# If the second of those two lost fragments is retransmitted, the new bitmap, 1111011, does not
# match the regex. If, instead, the first of those fragments is retransmitted, the new bitmap
# 1111101 does match the regex. As the sender should retransmit these messages sequentially,
# the SSN of the resent All-1 and the penultimate fragment are still not consecutive.
# The only way for these two SSNs to be consecutive in these cases
# is that the penultimate fragment fills the bitmap in the 6th bit,
# and the last fragment is the All-1.
# This reasoning is still valid when the last window does not contain WINDOW_SIZE fragments.
# These particular cases validate the use for this regex matching.
# Remember that 1111011 is NOT a valid bitmap.
# In conclusion, AFTER the regex matching,
# we should check if the SSNs of the two last received fragments are consecutive.
# The second to last fragment has the highest SSN registered in the JSON.
# We should consider only the SSNs of the last window. If there is a retransmission in a window
# prior to the last, the reasoning fails since the All-1 is always consecutive to a
# retransmitted fragment of a non-final window.
# If the All-1 is the only fragment of the last window (bitmap 0000001), and bitmap check of
# prior windows has passed, check the consecutiveness of the last All-0 and the All-1.
sequence_numbers = json.loads(
read_blob(BUCKET_NAME, "SSN"))
# This array has the SSNs of the last window.
# last_window_ssn = list(sequence_numbers.values())[current_window * profile.WINDOW_SIZE + 1:]
# If this array is empty, no messages have been received in the last window. Check if the
# last All-0 and the All-1 are consecutive. If they are not, there are lost fragments. If they
# are, the All-0 may have been retransmitted.
# print(last_window_ssn)
# The last sequence number should be the highest of these values.
last_sequence_number = max(
list(map(int, list(sequence_numbers.values()))))
print(
f"All-1 sequence number {sigfox_sequence_number}")
print(f"Last sequence number {last_sequence_number}")
if int(sigfox_sequence_number) - int(
last_sequence_number) == 1:
print(
"[ALL1] Integrity checking complete, launching reassembler."
)
# All-1 does not define a fragment number, so its fragment number must be the next
# of the higest registered fragment number.
last_index = max(
list(map(int, list(
sequence_numbers.keys())))) + 1
upload_blob(
BUCKET_NAME, data[0].decode("ISO-8859-1") +
data[1].decode("utf-8"),
f"all_windows/window_{current_window}/"
f"fragment_{current_window}_{last_index}")
try:
_ = requests.post(url=REASSEMBLER_URL,
json={
"last_index": last_index,
"current_window":
current_window,
"header_bytes":
header_bytes
},
timeout=0.1)
except requests.exceptions.ReadTimeout:
pass
# Send last ACK to end communication (on receiving an All-1, if no fragments are lost,
# if it has received at least one tile, return an ACK for the highest numbered window we
# currently have tiles for).
print("[ALL1] Preparing last ACK")
bitmap = ''
for k in range(profile.BITMAP_SIZE):
bitmap += '0'
last_ack = ACK(profile=profile,
rule_id=rule_id,
dtag=dtag,
w=zfill(format(window_ack, 'b'), m),
c='1',
bitmap=bitmap_ack)
response_json = send_ack(request_dict, last_ack)
print(f"200, Response content -> {response_json}")
print("[ALL1] Last ACK has been sent.")
return response_json, 200
# If the last two fragments are not consecutive, or the bitmap didn't match the regex,
# send an ACK reporting losses.
else:
# Send NACK at the end of the window.
print("[ALLX] Sending NACK for lost fragments...")
ack = ACK(profile=profile,
rule_id=rule_id,
dtag=dtag,
w=zfill(format(window_ack, 'b'), m),
c='0',
bitmap=bitmap_ack)
response_json = send_ack(request_dict, ack)
return response_json, 200
return '', 204
else:
print(
'Invalid HTTP Method to invoke Cloud Function. Only POST supported'
)
return abort(405)