server.py

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

import hashlib
from data_packet import *
import socket
import random
global expected_pkt, curr_pkt, pkt_buffer, pkt_list

class server:

	def __init__(self, server_IP, server_port):
		self.server_IP=server_IP
		self.server_port=server_port
		self.ack_port= server_port+5

		server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
		server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
		server_socket.bind(('', server_port))
		self.server_socket=server_socket

		ack_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
		ack_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
		ack_socket.bind(('', self.ack_port))
		self.ack_socket= ack_socket


	def receive(self):
		global expected_pkt, curr_pkt, pkt_buffer, pkt_list
		expected_pkt=0
		curr_pkt=-1
		pkt_buffer=[]
		pkt_list=[]
		flag=False

		while True:
			data, from_address = self.server_socket.recvfrom(1024)
			# print(getdict(data))
			client_address = (from_address[0],from_address[1]+5)
			temp=getdict(data)
			# r = random.random()
			# if(r<=0.8):
			# 	print("Packet Loss")
			# 	continue
			if(checkSumVerification(data)):
				ackpkt= createAck(temp['number'])
				self.ack_socket.sendto(ackpkt,client_address)
				if(temp['number']==expected_pkt):
					expected_pkt+=1
					curr_pkt=temp["number"]
					pkt_list.append(data)
					while pkt_buffer and pkt_buffer[0]==expected_pkt:
						curr_pkt=expected_pkt
						expected_pkt+=1
						pkt_buffer.remove(pkt_buffer[0])
						pkt_buffer.sort()

				elif( temp['number']>expected_pkt and temp['number'] not in pkt_buffer):
					pkt_list.append(data)
					pkt_buffer.append(temp['number'])
					pkt_buffer.sort()

			for pkt in pkt_list:
				temp= getdict(pkt)
				if(temp['number']==curr_pkt):
					if(temp['pkt_type']=='close_pkt'):
						flag=True
						break

			if flag:
				break

		for i in range(len(pkt_list)):
			temp=getdict(pkt_list[i])
			pkt_list[i]=temp

		final_data_list = sorted(pkt_list,key=lambda k: k['number'])

		for pkt in final_data_list:
			if(pkt["pkt_type"]=="file_pkt"):
				filename="output_"+bytes(pkt['data']).decode('utf-8')
				break

		fd=open(filename,"wb")
		for pkt in final_data_list:
			# print("hey",pkt)
			if(pkt["pkt_type"]=="data_pkt"):
				fd.write(bytes(pkt['data']))
		# close(filename)