Check if table element exists

Development
1

Hi,

I would like to check if a certain table element exists and then take corresponding action like the following:

if (exists(mytable[“my_dynamic_name”]))

do something
else
do something else

Can someone give me a hint?
Reinhard

2

Use "in":

if ("my_dynamic_name" in mytable)

Johanna

3

You're looking for 'in'

http://try.bro.org/#/?example=basics-composite-types-table

4

(Not sure if I am interpreting your question right but here is how I read it)

basically use "in" operator

local my_ip_table : table[addr] of bool ;

local ip: addr = 127.0.0.1

if ( ip in my_ip_table)
  found
else
  not found

btw, you can also use "!in" operator too which is rather more handy

if (something !in table)
  initialize it here
  table[something] = Blah;

or

most of scripts just flat return in membership doesn't exist that helps
eliminate a lot of unneeded run through scripts.

if (ip !in Site::local_nets)
  return

<do rest of the heuristics here for local IPs>

Here is a (rather complicated but) useful example which stretches
above problem with an extended use-case:

/usr/local/bro/share/bro/policy/frameworks/software/vulnerable.bro

Hope this helps. Let me know if you need more clearifications.

Aashish

5

Thank you! Exactly what I was looking for