Help writing a PHP function to parse a long hex array

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#1

Hello all,

I’m trying to add support for Avaya ERS vlan discovery.

The ERS switches report VLAN port memebers using a long hex string, much like the Q-Bridge MIB, but longer.
Since you can have a stack of upto 8 50 port switches, the hex string is always 64 octets, even if you just have a single 24 port switch.
Example output for one VLAN on a 26 port switch:
7F FF FF E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

There is already a function in includes\functions.php that will take a bitmask like this and return an array of port ids, q_bridge_bits2indices()
But this does not return anything if I send the above mask to it.
I think this is likely to be down to the length.

That mask is really 8 x 8 octets, each set of 8 octets being a single switch in the stack

I don’t really know any PHP, so I’m looking for help in creating a new function to return an array of port indexes from the above bitmask.

The sticky bit is this, if I have 2 x 26 port switches in a stack with all ports in the VLAN, I will get this output:
7F FF FF E0 00 00 00 00 7F FF FF E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
And would need an array returning with ports 1-52 in it.
But if I had 1 x 50 port and 1 x 26 port switch I would get this output:
‭7F FF FF FF FF FF E0 00‬ 7F FF FF E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
And would need an array returning with ports 1-76 in it.

I hope that all makes sense.

#2

This seems to work for me:

$result =  q_bridge_bits2indices('7F FF FF E0 00 00 00 00 7F FF FF E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00');
print_r($result);

Array
(
    [0] => 2
    [1] => 3
    [2] => 4
    [3] => 5
    [4] => 6
    [5] => 7
    [6] => 8
    [7] => 9
    [8] => 10
    [9] => 11
    [10] => 12
    [11] => 13
    [12] => 14
    [13] => 15
    [14] => 16
    [15] => 17
    [16] => 18
    [17] => 19
    [18] => 20
    [19] => 21
    [20] => 22
    [21] => 23
    [22] => 24
    [23] => 25
    [24] => 26
    [25] => 27
    [26] => 66
    [27] => 67
    [28] => 68
    [29] => 69
    [30] => 70
    [31] => 71
    [32] => 72
    [33] => 73
    [34] => 74
    [35] => 75
    [36] => 76
    [37] => 77
    [38] => 78
    [39] => 79
    [40] => 80
    [41] => 81
    [42] => 82
    [43] => 83
    [44] => 84
    [45] => 85
    [46] => 86
    [47] => 87
    [48] => 88
    [49] => 89
    [50] => 90
    [51] => 91
)
#3

Hmm, @murrant how are you testing that?
If there is an easy way of just testing that function I’ll have a play.

Also, the result is wrong.
It should be:

[0] => 1
[1] => 2
[2] => 3
...
[49] => 50
[50] => 51
[51] => 52
#4

You can just do:

<?php

$init_modules = array();
require __DIR__ . '/includes/init.php';

$result =  q_bridge_bits2indices('7F FF FF E0 00 00 00 00 7F FF FF E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00');
print_r($result);
#5

thanks @murrant and @laf, it helps being able to easily play around with the code.

So there is an off by one error, but I can easily fix that. (this is because the MSB is always 0, port 1 is represented by the 2nd MSB)

I’m trying to work out how to sort the untagged VLAN.

The avaya reports this differently.
Instead of a bit mask, it returns a list of ports with the PVID (or default) vlan, like this:

SNMP[/usr/bin/snmpbulkwalk -v2c -c COMMUNITY -OQUs -m RC-VLAN-MIB -M /opt/librenms/mibs:/opt/librenms/mibs/nortel udp:HOSTNAME:161 rcVlanPortDefaultVlanId]
rcVlanPortDefaultVlanId.1 = 350
rcVlanPortDefaultVlanId.2 = 350
rcVlanPortDefaultVlanId.3 = 350
rcVlanPortDefaultVlanId.4 = 350

So the PVID of ports 1-4 is 350.

If I do this:

$untagged_ids = snmpwalk_cache_oid($device, 'rcVlanPortDefaultVlanId', array(), 'RC-VLAN-MIB');
  echo "printing result...";
  print_r($untagged_ids);

I get this back:

printing result...Array
(
    [1] =>  Array
        (
            [rcVlanPortDefaultVlanId] => 350
        )

    [2] => Array
        (
            [rcVlanPortDefaultVlanId] => 350
        )

    [3] => Array
        (
            [rcVlanPortDefaultVlanId] => 350
        )

    [4] => Array
        (
            [rcVlanPortDefaultVlanId] => 350
        )

)

I need to flatten this to an array like this:

Array
(
    [1] => 350
    [2] => 350
    [3] => 350
    [4] => 350
)

Then I can write a function to build a list of untagged ports for each vlan.

Is there already a function for this? Or am I approaching this wrong?

thanks

#6

I’m not aware of any function, why not just loop through the array to get what you want?

#7

yea, it was obvious how to do it once I had read a bit more about PHP.

Done and PR sent: 7098.

I’ll apologise now for the code…

#8