data_packet.py

# Rahul R Shevade - 2017B3A70878H
# Kasam Vamshi - 2017B3A70740H
# Shanmukh Kaliprasad Padmanabhuni - 2017B3A71048H
# Pranav V Grandhi - 2017B2A71604H
# Suhas Reddy N - 2017B4A70885H
# Vashist SLN - 2017B3A70381H

import json
import hashlib
import sys

def checksum(data,pkt_type,number,status):
    hash_str = str(data) + ":" + pkt_type + ":" + str(number) + ":" + str(status)
    return hashlib.md5(hash_str.encode()).hexdigest()

def make_pktlist(content, filename):
	packet_list=[]
	pno=0
	while(len(content) !=0):
		data= content[:64]
		pno+=1
		csum= checksum(data,"data_pkt",pno-1, False)
		data= jsonify(data, "data_pkt",pno-1,False,csum)
		packet_list.append(data)
		content=content[64:]

	# print("MSS:",sys.getsizeof(packet_list[0]))
	pno+=1
	file=filename
	data= bytes(file,'utf-8')
	csum= checksum(data,"file_pkt",pno-1, False)
	data= jsonify(data, "file_pkt",pno-1,False,csum)
	packet_list.append(data)

	pno+=1
	bye="Bye"
	data= bytes(bye,'utf-8')
	csum= checksum(data,"close_pkt",pno-1, False)
	data= jsonify(data, "close_pkt",pno-1,False,csum)
	packet_list.append(data)
	return packet_list


def checkSumVerification(pkt):
	currpkt= json.loads(pkt.decode('utf-8'))
	d=bytes(currpkt["data"])
	t=currpkt["pkt_type"]
	n=currpkt["number"]
	s=currpkt["status"]
	# print("csum:", checksum(d,t,n,s))
	if(checksum(d,t,n,s)==currpkt['checksum']):
		return True
	else:
		return False

def check_ack(ack):
	ack_data = bytes(ack['data'])
	if (checksum(ack_data, ack['pkt_type'], ack['number'], ack['status']) == ack['checksum']):
		return True
	else:
		return False

def jsonify(data,pkt_type,number,status,csum):
	pkt_dict={
		"data": list(data),
		"pkt_type": pkt_type,
		"number": number,
		"status": status,
        "checksum": csum

	}
	pkt_json= json.dumps(pkt_dict).encode('utf-8')
	return pkt_json

def getdict(pkt):
	return json.loads(pkt.decode('utf-8'))

def createAck(data_num):
	data="Ack Sent"
	data= bytes(data,'utf-8')
	csum=checksum(data,"ack",data_num,True)
	ackpkt=jsonify(data,"ack",data_num,True,csum)
	return ackpkt