附加字典时出现KeyError

Question

I am getting a key error while trying to add a variable from a parsed pcap file.

Here I am trying to get the last time stamp but I get a key error

KeyError: 'UPD'


lst_timestamp = {}

for ts, buf in packets:
    eth = dpkt.ethernet.Ethernet(buf)
    ip = eth.data
    protocol_number = ip.p
    traffic_type = protocoltype.proto[protocol_number]
    if traffic_type not in traffic_types:
        traffic_types.append(traffic_type)

    if traffic_type in no_packets: # check the key is in the dictionary
        no_packets[traffic_type] += 1
    else:
        no_packets[traffic_type] = 1
        
    if traffic_type not in fst_timestamp:
        fst_timestamp[traffic_type] = ts
    
    if traffic_type in lst_timestamp:
        lst_timestamp[traffic_type] = ts

The error is occurring here:

if traffic_type in lst_timestamp:
    lst_timestamp[traffic_type] = ts

I am fairly new to python so I have tried to find why this error occurs but I can't figure it out, any help would be much apricated.

Full code.

import dpkt
import socket
from tabulate import tabulate
import protocoltype

def main() -> list:    
    """parse pcap"""
    pcap_file = "evidence-packet-analysis.pcap"

    packets = []
    open_file = open(pcap_file, "rb")    
    for ts, buf in dpkt.pcap.Reader(open_file):
        packets.append((ts, buf))
    open_file.close()

    print(f"'{pcap_file}' Successfully Read")

    table(packets)

def table(packets):
    traffic_types = []
    no_packets = {}
    fst_timestamp = {}
    lst_timestamp = {}

    for ts, buf in packets:
        eth = dpkt.ethernet.Ethernet(buf)
        ip = eth.data
        protocol_number = ip.p
        traffic_type = protocoltype.proto[protocol_number]
        if traffic_type not in traffic_types:
            traffic_types.append(traffic_type)

        if traffic_type in no_packets: # check the key is in 
the dictionary
            no_packets[traffic_type] += 1
        else:
            no_packets[traffic_type] = 1
        
        if traffic_type not in fst_timestamp:
            fst_timestamp[traffic_type] = ts
    
        if traffic_type in lst_timestamp:
            lst_timestamp[traffic_type] = ts
        
    rows = []
    for traffic_type in traffic_types:
        rows.append([traffic_type, no_packets[traffic_type], 
fst_timestamp[traffic_type], lst_timestamp[traffic_type], 0])

    print(tabulate(
        rows,
        headers=["traffic_type", "no_packets", "fst_timestamp", 
"lst_timestamp", "mean_packet_length"]
    ))


if __name__ == "__main__" :
    main()

The module protocoltype is just a dictionary linking protocol numbers to protocol type

Answer 1

KeyError: 'UPD'

Ok where's the 'UPD'?

There's no 'UPD' key in your code