def mc_recv_file(fromnicip, mcgrpip, mcport_recv, mcport_send, use_buffer):
# 1. Get a socket to receive data with and a socket to send data with
receiver = common.prep_receiver(fromnicip, mcgrpip, mcport_recv)
endpoint = (mcgrpip, mcport_send)
sender = common.prep_sender(fromnicip)
# 2. Receive metadata
filename, datasize, remote_checksum = recv_metadata(receiver, sender, \
endpoint)
# The buffer is just a hash table, where each key is a sequence number and
# each value is the file content in bytes; this is only used if the option
# is chosen by user
content_buffer = {}
# 3. Receive file content
more = '1'
while True:
if more == '1':
packet, opcode, _ = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, None)
if opcode != common.CONTENT_OP:
continue
else:
break
seq_num = int(packet[1:common.SEQ_NUM_LEN + 1])
print("Received file packet number:", seq_num)
more = packet[common.SEQ_NUM_LEN + 1:common.SEQ_NUM_LEN + 2]
content = packet[common.SEQ_NUM_LEN + 2:common.BLOCKSIZE \
+ common.SEQ_NUM_LEN + 2]
if not use_buffer:
write_bytes(filename, common.BLOCKSIZE, seq_num, content.encode())
else:
content_buffer[seq_num] = content.encode()
# Write the buffer to the file if user picked this option
if use_buffer:
write_buffer(filename, content_buffer)
# 4. Check if local data matches remote and send feedback
error = None
local_checksum = common.hash_file(common.BLOCKSIZE, filename)
if local_checksum != remote_checksum:
sender.sendto((common.FEEDBACK_OP + common.ERROR_OP).encode(),
endpoint)
error = True
else:
sender.sendto((common.FEEDBACK_OP + common.DONE_OP).encode(), endpoint)
error = False
print("Checksum of local data:", local_checksum)
# 5. Release socket resources and indicate success/error to user
common.release_rsrcs([sender, receiver])
if error:
common.exit_err(f'Error: could not properly receive {filename}, ' \
+ 'aborting...\n', 1)
else:
print(f'Completed: received {filename}\n', file=sys.stderr)
def mc_send_file(hostip, mcgrpip, mcport_send, mcport_recv, filename):
datasize = os.stat(filename).st_size
print(f'Sending file: {filename}\n')
if datasize > (common.MAX_SEQ * common.BLOCKSIZE):
print('WARNING: data size exceeds 1-petabyte, transmitted data will be'\
+ ' truncated!', file=sys.stderr)
# 1. Get a socket to send data with and a socket to receive data with
endpoint = (mcgrpip, mcport_send)
sender = common.prep_sender(hostip)
receiver = common.prep_receiver(hostip, mcgrpip, mcport_recv)
# 2. Send metadata
send_metadata(sender, endpoint, receiver, filename, datasize)
# 3. Read the file and the transmit the file content in packets of BLOCKSIZE
# data length; the single-byte prefix for file content is CONTENT_OP
with open(filename, 'rb') as f:
seq_num = 1
more = '0'
packets_left = count_blocks(common.BLOCKSIZE, datasize, filename)
content_bytes = f.read(common.BLOCKSIZE)
while content_bytes and seq_num <= common.MAX_SEQ:
content_sent = False
more = '1' if packets_left > 1 else '0'
packet = common.CONTENT_OP.encode() \
+ str(seq_num).zfill(common.SEQ_NUM_LEN).encode() \
+ more.encode() \
+ content_bytes
while not content_sent:
sender.sendto(packet, endpoint)
feed_packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if not timedout and opcode == common.FEEDBACK_OP and \
feed_packet[1:common.SEQ_NUM_LEN + 1] == \
str(seq_num).zfill(common.SEQ_NUM_LEN):
content_sent = True
seq_num += 1
packets_left -= 1
content_bytes = f.read(common.BLOCKSIZE)
time.sleep(common.PACKET_DELAY)
# 4. Handle final feedback and release socket resources
while True:
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if not timedout and opcode == common.FEEDBACK_OP:
break
print('Final feedback:', packet[1])
common.release_rsrcs([sender, receiver])
if packet[1] == common.ERROR_OP:
common.exit_err(f'Error: could not properly send {filename}, ' \
+ 'aborting...\n', 1)
elif packet[1] == common.DONE_OP:
print(f'\nCompleted: sent {filename}', file=sys.stderr)
else:
print('Unable to confirm final transmission status.')
def send_metadata(sender, endpoint, receiver, filename, datasize):
filename_sent = False
datasize_sent = False
checksum_sent = False
# Transmit the filename in a packet
# The filename is a byte string of FNAME_LEN length; the single-byte prefix
# for filename is FNAME_OP
fname_bytes = (common.FNAME_OP + filename[:common.FNAME_LEN]).encode()
print('Filename sent:', fname_bytes)
while not filename_sent:
sender.sendto(fname_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if not timedout and opcode == common.FEEDBACK_OP \
and packet[1] == common.ACK_OP:
filename_sent = True
print('Filename feedback:', packet[1])
# Transmit the data size in a packet
# The data size is a byte string of DATASIZE_LEN length; the single-byte
# prefix for data size is DATASIZE_OP
datasize_bytes = (common.DATASIZE_OP \
+ str(datasize)[:common.DATASIZE_LEN]).encode()
print('Data size sent:', datasize_bytes)
while not datasize_sent:
sender.sendto(datasize_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if not timedout and opcode == common.FEEDBACK_OP \
and (packet[1] == common.ACK_OP or packet[1] == common.STOP_OP):
datasize_sent = True
if packet[1] == common.STOP_OP:
common.release_rsrcs([sender, receiver])
common.exit_err('Aborting due to receiver request...', 0)
print('Data size feedback:', packet[1])
# Generate and transmit SHA-2 256-bit checksum for file being transmitted in
# a packet, the hexadecimal digest transmitted is a 64-byte string; the
# single-byte prefix for checksum is HASH_OP, the string length of the
# digest is also found as HASH_LEN
hexdigest = common.hash_file(common.BLOCKSIZE, filename)
hexdigest_bytes = (common.HASH_OP + hexdigest).encode()
print('Checksum sent:', hexdigest_bytes)
while not checksum_sent:
sender.sendto(hexdigest_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if not timedout and opcode == common.FEEDBACK_OP \
and packet[1] == common.ACK_OP:
checksum_sent = True
print('Checksum feedback:', packet[1])
def main(argv):
if len(argv) != 6:
common.exit_err('Usage: ' + argv[0] + ' host_ip mcast_group_ip ' \
+ 'mcast_port_send mcast_port_recv file_to_send', 1)
hostipaddr = argv[1]
mcgrpipaddr = argv[2]
mcport_send = int(argv[3])
mcport_recv = int(argv[4])
filename = argv[5]
if not os.path.isfile(filename):
common.exit_err(f'File: {filename} not found!', 1)
mc_send_file(hostipaddr, mcgrpipaddr, mcport_send, mcport_recv, filename)
def recv_metadata(receiver, sender, endpoint):
filename_rcvd = False
datasize_rcvd = False
checksum_rcvd = False
# Check free space on current working directory
_, _, free = shutil.disk_usage(__file__)
# Wait for metadata
while not filename_rcvd or not datasize_rcvd or not checksum_rcvd:
packet, opcode, _ = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, None)
if opcode == common.FEEDBACK_OP and packet[1] == common.STOP_OP:
common.release_rsrcs([sender, receiver])
common.exit_err('Aborting due to sender request...', 0)
# Receive the filename packet
# The filename is a byte string of FNAME_LEN length; the single-byte
# prefix for filename is FNAME_OP
if opcode == common.FNAME_OP:
filename = packet[1:common.FNAME_LEN + 1]
filename_rcvd = True
print("Filename received:", filename)
sender.sendto((common.FEEDBACK_OP + common.ACK_OP).encode(), \
endpoint)
# Receive the data size packet
# The data size is a byte string of DATASIZE_LEN length; the single-byte
# prefix for data size is DATASIZE_OP
if opcode == common.DATASIZE_OP:
datasize = int(packet[1:common.DATASIZE_LEN + 1])
datasize_rcvd = True
print("Data size received:", datasize)
if free < datasize:
# Tell sender to stop sending anything and exit.
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, f'Not enough ' \
+ 'free space available for file, aborting...', 1)
sender.sendto((common.FEEDBACK_OP + common.ACK_OP).encode(), \
endpoint)
# Receive the remote checksum packet
# The checksum is a 64-byte string hexadecimal digest; the single-byte
# prefix for checksum is HASH_OP, the string length of the digest is
# also found as HASH_LEN
if opcode == common.HASH_OP:
checksum = packet[1:common.HASH_LEN + 1]
checksum_rcvd = True
print("Checksum received:", checksum)
sender.sendto((common.FEEDBACK_OP + common.ACK_OP).encode(), \
endpoint)
return (filename, datasize, checksum)
def help_and_exit(argv):
common.exit_err('Usage: ' + argv[0] + ' -i|-b from_nic_by_host_ip ' \
+ 'mcast_group_ip mcast_port_recv mcast_port_send', 1)
def send_metadata(sender, endpoint, receiver, filename, datasize):
# Transmit the filename in a packet
# The filename is a byte string of FNAME_LEN length; the single-byte prefix
# for filename is FNAME_OP
fname_bytes = (common.FNAME_OP + filename[:common.FNAME_LEN]).encode()
print('Filename sent:', fname_bytes)
sender.sendto(fname_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if timedout:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Timed out, aborting...', 1)
if opcode != common.FEEDBACK_OP:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Feedback invalid, aborting', 1)
print('Filename feedback:', packet[1])
# Transmit the data size in a packet
# The data size is a byte string of DATASIZE_LEN length; the single-byte
# prefix for data size is DATASIZE_OP
datasize_bytes = (common.DATASIZE_OP \
+ str(datasize)[:common.DATASIZE_LEN]).encode()
print('Data size sent:', datasize_bytes)
sender.sendto(datasize_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if timedout:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Timed out, aborting...', 1)
if opcode != common.FEEDBACK_OP:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Feedback invalid, aborting', 1)
print('Data size feedback:', packet[1])
if packet[1] == common.STOP_OP:
common.release_rsrcs([sender, receiver])
common.exit_err('Aborting due to receiver request...', 0)
# Generate and transmit SHA-2 256-bit checksum for file being
# transmitted in a packet, the hexadecimal digest transmitted is a
# 64-byte string; the single-byte prefix for checksum is HASH_OP, the
# string length of the digest is also found as HASH_LEN
hexdigest = common.hash_file(common.BLOCKSIZE, filename)
hexdigest_bytes = (common.HASH_OP + hexdigest).encode()
print('Checksum sent:', hexdigest_bytes)
sender.sendto(hexdigest_bytes, endpoint)
packet, opcode, timedout = \
common.get_packet(receiver, common.MAX_PACKET_SIZE, \
common.BLOCKING_WAIT)
if timedout:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Timed out, aborting...', 1)
if opcode != common.FEEDBACK_OP:
common.make_clean_exit(sender, receiver, (common.FEEDBACK_OP \
+ common.STOP_OP).encode(), endpoint, \
'Feedback invalid, aborting', 1)
print('Checksum feedback:', packet[1])
