x0yZYDJ6

1#
2# Listener
3#
4from scapy.all import *
5import os
6import hashlib
7import json
8
9# id = 1  --> Handshake packets
10# id = 2  --> file chunks packet
11# id = 3  --> request for resend
12
13class Receiver:
14    def __init__(self):
15        self.ip_client = '192.168.1.122'
16        self.chunk_list = []
17        self.file_size = 0
18        self.file_name = ''
19        self.total_chunks = 0
20        self.sha1_digest = 0
21        self.transport_properties_dict = {}
22
23    def handshake(self):
24        while True:
25            res = sniff(count=1, filter=f"src host {self.ip_client} and icmp")
26            if res[ICMP][0].id == 1:
27                break
28        self.transport_properties_dict = json.load(res[Raw])
29        self.file_name = self.transport_properties_dict["file_name"]
30        self.file_size = self.transport_properties_dict["file_size"]
31        self.sha1_digest = self.transport_properties_dict["file_sha1"]
32        self.total_chunks = self.transport_properties_dict["num_of_chunks"]
33
34        pkt = IP(dst=self.ip_client)/ICMP(id=1)/Raw(load='sendnow123')
35        send(pkt)
36        return True
37
38    def recv_file(self):
39
40        # Chunks list initialization
41        for i in range(self.total_chunks):
42            self.chunk_list[i] = None
43
44        while True:
45            res = sniff(count=1, filter=f"src host {self.ip_client} and icmp")
46            if res[ICMP].id == 2:
47                self.chunk_list[[ICMP][0].seq] = res[ICMP][0][Raw].load
48                if res[ICMP][0].seq == self.total_chunks - 1:
49                    break
50
51            if None not in self.chunk_list:
52                with open(self.file_name, 'wb') as f:
53                    for item in self.chunk_list:
54                        f.write(item)
55                        return True
56
57            if None in self.chunk_list:
58                return False
59
60    def hash_caluation(self):
61        BLOCKSIZE = 65536
62        hasher = hashlib.sha1()
63        with open(self.file_name, 'rb') as f:
64            buf = f.read(BLOCKSIZE)
65            while len(buf) > 0:
66                hasher.update(buf)
67                buf = f.read(BLOCKSIZE)
68        local_sha1_digest = hasher.hexdigest()
69        if self.sha1_digest == local_sha1_digest:
70            print(f'file digest is OK: {self.sha1_digest}')
71            return True
72        else:
73            print(f'file digest is wrong: local_sha1_digest')
74            return False
75
76    def packet_loss(self):
77        while None in self.chunk_list:
78            # Search chunks list for empty places (None) and asks the client to send again.
79            for index in range(len(self.chunk_list)):
80                # None chunk_list -- > needs resend.
81                if not self.chunk_list[index]:
82                    pkt = IP(dst=self.ip_client)/ICMP(seq=index, id=3)
83                    send(pkt)
84                    res = sniff(count=1, filter=f"src host {self.ip_client} and icmp")
85                    if res[ICMP][0].id == 3:
86                        self.chunk_list[index] = res[ICMP][0][Raw].load
87        # Update the server that all chunks are in place.
88        pkt = IP(dst=self.ip_client)/ICMP(id=4)
89        send(pkt)
90        # writing to file.
91        with open(self.file_name, 'wb') as f:
92            for item in self.chunk_list:
93                f.write(item)
94                self.hash_caluation()
95
96
97
98server = Receiver()
99operation = server.handshake()
100if operation:
101    operation = server.recv_file()
102    if operation:
103        operation = server.hash_caluation()
104        if operation:
105            print("File received successfully!!!")
106        else:
107            server.packet_loss()
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