Forum Discussion
Ten_92952
Nimbostratus
Nimbostratusirule question
Would someone be able to tell my why the syntax for this irule is acceptable to the BigIp
when RULE_INIT {
Purpose:
This rule allows the ace servers access to the acme web
site servers
}
when CLIENT_ACCEPTED {
if { [matchclass [IP::client_addr] equals $::ace_servers] }{
} else {
discard
}
}
but this syntax
when RULE_INIT {
Purpose:
This rule allows the ace servers access to the acme web
site servers
}
when CLIENT_ACCEPTED {
if { [matchclass [IP::client_addr] equals $::ace_servers]}
else {
discard
}
}
gives the following error?
01070151:3: Rule [server_access] error: line 10: [undefined procedure: else] [else] line 10: [deprecated usage, use else or elseif] [ ]
thanks
3 Replies
HamishCirrocumulus
Short answer is because the first is syntactically correct, but the second isn't... It's missing the block of something to do.
In languages like C or perl, you could put a ';' in place to denote what is essentially a no-op... But tcl doesn't have that syntax... It's expecting something to do. And 'else' isn't a valid 'something to do'. It's part of the control itself. It's also IMO bad practice to write code such that an evaluation results in a NOOP and you have an else there instead (Sorry, comp sci education coming out in me again).
A better syntax (If you really don't want to do anything from the if{} statement is to negate the test. Then you don't need the else {} at all.
H
hoolioCirrostratus
Also, for v9.4.4 or higher, you should remove the $:: prefix from the datagroup name. And in 10.0+ you should change matchclass to class match:
http://devcentral.f5.com/wiki/default.aspx/iRules/class
Aaronthe block
if { [matchclass [IP::client_addr] equals $::ace_servers]} else { discard }should be
if { [matchclass [IP::client_addr] equals $::ace_servers]} { } else { discard }
