Python Array Function

Question

I'm busy writing a reader for my network sniffer. It writes all sort of data into a MySQL database. I'm trying to print the data in a readable way into my console. I've build two function to print my data

def printHeader(destination, source, protocol):
print('Ethernet Frame:')
print(('| - Destination: {}, Source: {}, Protocol: {}')
      .format(destination, source, protocol))

def printDNS(version, header_length, ttl, protocolEGP, source, target, source_port, destination_port, length):
    print('| - IPv4 Packet:')
    print(('    | - Version: {}, Header Length: {}, TTL: {},'
           ).format(version, header_length, ttl))
    print(('    | - Protocol: {}, Source: {}, Target: {}'
           ).format(protocolEGP, source, target))
    print('    | - UDP Segment:')
    print(('        | - Source Port: {}, Destination Port: {}, '
           'Length: {}').format(source_port, destination_port, length))

def openCON(query):

    conn = cymysql.connect(host='*', port=3306, user='root', passwd='*', db='python')
    cur = conn.cursor()
    cur.execute(query)
    data = []
    for row in cur:
        data.extend(row)
    cur.close()
    conn.close()
    return data

Now when I run a query I retrieve something like this:

[19, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 52698, 53, 28485, 18, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 52681, 53, 28485, 20, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 34310, 53, 28502]

I'm trying to iterate over the array to send the correct array indexes to the functions

Example : first array[1:3] should be sent to printHeader() the second part array[4:11] should be sent to printDNS() the first array is the packet number, not using that one in this example. then I needs to send array [13:15] to printHeader() etc.

I can't seem to figure how to code this in a nice fashion, if tried something like, but as we all know its horrible; also tried looping but with none success so far

DNS = openCON(query)

z = 1
x = 2
c = 3
a = 4
s = 5
d = 6
g = 7
h = 8
j = 9
k = 10
l = 11
p = 12

while True:
    if p < len(DNS):
        printHeader(DNS[(z)], DNS[(x)], DNS[(c)])
        printDNS(DNS[(a)], DNS[(s)], DNS[(d)], DNS[(g)], DNS[(h)], DNS[(j)], DNS[(k)], DNS[(l)], DNS[(p)])
        z += 12
        x += 12
        c += 12
        a += 12
        s += 12
        d += 12
        g += 12
        h += 12
        j += 12
        k += 12
        l += 12
    else:
        break

Can somebody help me push in the right direction to code this nice and efficient? I've thought maybe I should not query the entire table but only a row at the time.

Thanks in advance.

score 1 · Accepted Answer · edited May 23 '17 at 10:25

Instead of putting mulitple dns data in a single list, you could construct a list of lists in openCON. Just replace extend with append. Then the return value will be more logically laid out:

[
    [19, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 52698, 53, 28485], 
    [18, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 52681, 53, 28485], 
    [20, '88:9F:FA:D3:0B:5F', '192.168.178.24', 8, 4, 20, 64, 17, '212.54.40.25', 34310, 53, 28502]
]

Sounds like you already know about slice operations, which you should make use of here. You should also use the splat operator, *, when you pass the arrays as arguments to your functions.

dnsses = openCON(query)
for dns in dnsses:
    printHeader(*dns[0:3])
    printDNS(*dns[3:])

score 0 · Answer 2 · answered Oct 25 '13 at 14:19

Use slices. This feature can return sublist of a list like this:

a = [1, 2, 3, 4,5]
a[2:3]   # [3]
a[2:5]   # [3, 4, 5]
a[-4:-2] # [2, 3]
a[1:3]   # [2, 3]

This gices you ability easily define what elements should be passed to a function. Instead of

printHeader(DNS[(z)], DNS[(x)], DNS[(c)])

you can write

printHeader(DNS[:3])

Python Array Function

2 Answers2