How to use Or/And correctly

As with most languages, Tcl employs short-circuiting for logical operators, including the sugar operators ("and", "or" and "not") provided to iRules. As a consequence, when the following statement is evaluated:

if { [HTTP::host] contains "foo" or "bar" }

and it turns out that

[HTTP::host] contains "foo"

evaluates to True, then the second part does not evaluate. If it evaluates to False, then the

if

evaluates the literal string "bar", which isn't a boolean and will cause a run-time error. To test this, I use the trivial iRule:

when HTTP_REQUEST {
    if { [HTTP::host] contains "example.com" or "foo.com" } {
        log local0. "Yes: [HTTP::host]"
    }
}

I then submit two requests. The first sets the Host header to "www.example.com" and the second sets it to "www.foo.com". Here is what ends up in /var/log/ltm:

Apr  5 17:06:48 b201 info tmm3[25219]: Rule /Common/test-or : Yes: www.example.com
Apr  5 17:07:01 b201 err tmm[25219]: 01220001:3: TCL error: /Common/test-or  - can't use non-numeric string as operand of "||"     while executing "if { [HTTP::host] contains "example.com" or "foo.com" } {             log local0. "Yes: [HTTP::host]"         }"

So, just as I say, when the first condition matches, it's fine, but if does not, and the second condition is evaluated, a run-time error is raised.

Your second conditional is fine, and the run-time error is probably being raised in the body. I tested the following:

when HTTP_REQUEST {
    if { [HTTP::host] contains "example.com" or [HTTP::host] contains "foo.com" } {
        log local0. "Yes: [HTTP::host]"
    }
}

with the Host header set to "www.example.com" and "www.foo.com". /var/log/ltm shows the following:

Apr  5 17:09:59 b201 info tmm1[25219]: Rule /Common/test-or : Yes: www.example.com
Apr  5 17:10:01 b201 info tmm2[25219]: Rule /Common/test-or : Yes: www.foo.com

The problem likely arises because you did not quote the parameter passed to

HTTP::redirect

:

HTTP::redirect www.url.com[HTTP:uri]

In this case

[HTTP::uri]

could contain characters that Tcl won't accept in a statement. Remember that, when you employ the substitution operator (that is, [...]), the substitution occurs first, then the statement is evaluated. Imagine that

[HTTP::uri]

contains the (admittedly illegal) character ' ' (i.e., a space). It would result in a statement that looks like this:

HTTP::redirect www.url.com/foo bar/baz

Because of the space,

HTTP::redirect

is passed two parameters, but it only accepts one. There are other character combinations that can cause Tcl to hiccough. Anyhow, your best bet is to do this:

HTTP::redirect "www.url.com[HTTP::uri]"

If that doesn't solve your problem, you should pass along the log message (/var/log/ltm) associated with the failure.

In your case, there is no difference between Method 2 and Method 3. They will result in the same outcome. However, as you mention, parenthesis can be useful if you need to force order-of-evaluation. They don't hurt, in this case, and for longish conditional statements, they can make things clearer.