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server.py
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server.py
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import os
import threading
import hashlib
import xmlrpclib
import cPickle
import time
import socket
from Crypto.PublicKey import RSA
MAX_PEERS = 5
HEARTBEAT_TIMEOUT = 180
SHARD_SIZE = 64*1024
DATA_DIR = 'server_data' # data directory
SHARD_DIR = DATA_DIR + os.sep + 'shards/' # shards directory
META_FILe = DATA_DIR + os.sep + 'p2pmeta' # metadata file
#######################################
# Generate Public and Private key pair
#######################################
PUBLIC_KEY_FILE = 'server_public_key'
PRIVATE_KEY_FILE = 'server_private_key'
LOG_FILE = DATA_DIR + os.sep + 'server.log'
LOCAL_ADDRESS = ('localhost', 8080)
import utils
class Server(object):
def __init__(self):
print "starting server"
self.key = '' # generate public/private key
self.peers = {}
self.p2pfiles = [] # list of P2PFile
self.server_id = os.urandom(8).encode('hex')
self.max_peer_sem = threading.Semaphore(MAX_PEERS) # This is to control shard serving requests
self._load_files() # load metadata and create dirs
self.logger = utils.setup_logger(LOG_FILE) # setup logger
self._load_keys() # load publickey
self.heartbeat_thrd = threading.Timer(HEARTBEAT_TIMEOUT, self.check_clients) #Thread to monitor alive peers
self.heartbeat_thrd.setDaemon(True)
self.heartbeat_thrd.start()
# Create directories (if required) and load metadata
def _load_files(self):
if not os.path.exists(DATA_DIR):
os.makedirs(DATA_DIR)
os.makedirs(SHARD_DIR)
if os.path.isfile(META_FILe):
with open(META_FILe, 'rb') as fp:
self.p2pfiles = cPickle.load(fp)
for f in self.p2pfiles:
f.peer_ids.clear()
f.add_peer(self.server_id, LOCAL_ADDRESS)
# load private key
def _load_keys(self):
if os.path.isfile(PRIVATE_KEY_FILE):
with open(PRIVATE_KEY_FILE, 'r') as fp:
self.key = RSA.importKey(fp.read())
# save metadata information
def save_state(self):
with open(META_FILe, 'wb') as fp:
cPickle.dump(self.p2pfiles, fp)
return True
# This function is used to upload a file (used by console admin)
# Each file_data chunk is stored as a separate shard
def upload_file(self, file_name, file_data):
file_id = hashlib.md5(file_name).hexdigest()
self._log("uploading file: %s, fileid: %s, received bytes: %d" % (file_name, file_id, len(file_data.data)))
shard = utils.Shard(file_data.data, file_id)
shard.save(SHARD_DIR)
self._log("saved shard: %s" % shard.shard_id)
p2pfile = utils.P2PFile(file_name)
if p2pfile in self.p2pfiles:
p2pfile = self.p2pfiles[self.p2pfiles.index(p2pfile)]
else:
p2pfile.id = hashlib.md5(file_name).hexdigest()
self.p2pfiles.append(p2pfile)
p2pfile.size += len(file_data.data)
p2pfile.shard_ids.append(shard.shard_id)
p2pfile.add_peer(self.server_id, LOCAL_ADDRESS)
return True
# returns p2pfiles list
def get_files(self):
return cPickle.dumps(self.p2pfiles)
# returns filename list
def get_file_list(self):
return [x.filename for x in self.p2pfiles]
# given a filename it returns p2pfile object
def get_p2pfile(self, filename):
for p2pfile in self.p2pfiles:
if p2pfile.filename == filename:
return cPickle.dumps(p2pfile)
# given a p2pfile pdates it in local p2pfile list
def update_p2pfile(self, p2pfile, peer_id):
p2pfile = cPickle.loads(p2pfile)
if self.server_id in p2pfile.peer_ids:
p2pfile.remove_peer(self.server_id)
for f in self.p2pfiles:
if f.filename == p2pfile.filename:
f.peer_ids = p2pfile.peer_ids
return cPickle.dumps(p2pfile)
# serve shard given a shard id
def serve_shard(self, shard_id):
self.max_peer_sem.acquire()
self._log("Serving shard: %s" % shard_id)
with open(SHARD_DIR + shard_id, 'rb') as fp:
shard = cPickle.load(fp)
self.max_peer_sem.release()
return cPickle.dumps(shard)
self.max_peer_sem.release()
return False
# handle registration from clients
def register(self, _key):
client_id = hashlib.md5(_key).hexdigest()
self._log("Register request client ID: %s" % client_id)
server_ciphered_key = self.key.sign(client_id, None)
self.peers[client_id] = int(time.time())
return cPickle.dumps((client_id, server_ciphered_key))
# receive heartbeats from clients
def heartbeat(self, client_id, p2pfiles):
self._log("Heartbeat signal client ID: %s" % client_id)
if client_id in self.peers:
time_now = int(time.time())
self.peers[client_id] = time_now
p2pfiles = cPickle.loads(p2pfiles)
for p2pfile in p2pfiles:
server_file = self.p2pfiles[self.p2pfiles.index(p2pfile)]
server_file.peer_ids.update(p2pfile.peer_ids)
return self.get_files()
# monitor keep-alive from clients
def check_clients(self):
while True:
for client in self.peers.keys():
last_seen_time = int(time.time()) - self.peers[client]
if last_seen_time >= HEARTBEAT_TIMEOUT:
self._log("Killing client: %s , not seen within %d seconds" % (client, last_seen_time))
map(lambda p2pfile: p2pfile.remove_peer(client), self.p2pfiles)
del self.peers[client]
time.sleep(HEARTBEAT_TIMEOUT)
def _log(self, msg):
print msg
self.logger.info(msg)
# helper function to print file list from server
def list_files():
s = utils.get_connection(LOCAL_ADDRESS)
files = cPickle.loads(s.get_files())
for f in files: print f
# used to upload given file to server
def upload_file(name):
try:
s = utils.get_connection(LOCAL_ADDRESS)
file_list = cPickle.loads(s.get_files())
if filter(lambda x: x.filename == name, file_list):
print "File already exists on server"
return
with open(name, 'rb') as handle:
def read_chunk():
return handle.read(SHARD_SIZE)
for chunk in iter(read_chunk, ''):
data = xmlrpclib.Binary(chunk)
s.upload_file(name, data)
s.save_state()
except Exception as ext:
print "File upload error"
print ext
if __name__ == '__main__':
server = utils.threaded_server(LOCAL_ADDRESS)
server.register_instance(Server())
t = threading.Timer(1.0, server.serve_forever)
t.setDaemon(True)
t.start()
print "Server running at %s" % str(LOCAL_ADDRESS)
while True:
print "Press 1 to list files"
print "Press 2 to upload file"
print "Press 0 to exit"
arg = raw_input('Your option>')
if not arg: pass
elif arg[0] == '2':
print "Please enter the name of the file to upload: "
fname = raw_input()
upload_file(fname)
elif arg[0] == '1':
list_files()
elif arg[0] == '0':
break
pass
#server.serve_forever()