Irule help for host header redirection

if it's a list of hostnames that isn't too large and won't be changing too often, i would just use some or's:

when HTTP_REQUEST {
 if {([string tolower [HTTP::host]] equals "www.example.com") or ([string tolower [HTTP::host]] equals "abccorp.com" or [string tolower [HTTP::host]] equals "xyzmedia.ca")} {
  HTTP::redirect "https://mywebsite.com"
 }
}

if you want the irule to be more flexible and extensible in regards to adding hostnames, you should use a data group. create data-group (reference in irule below as hostname-data-group) with a list of the hostnames you want redirected, and use an irule similar to:

when HTTP_REQUEST {
 if { class match [string tolower [HTTP::host]] equals hostname-data-group } {
  HTTP::redirect "https://mywebsite.com"
 }
}

if it's a list of hostnames that isn't too large and won't be changing too often, i would just use some or's:

when HTTP_REQUEST {
 if {([string tolower [HTTP::host]] equals "www.example.com") or ([string tolower [HTTP::host]] equals "abccorp.com" or [string tolower [HTTP::host]] equals "xyzmedia.ca")} {
  HTTP::redirect "https://mywebsite.com"
 }
}

if you want the irule to be more flexible and extensible in regards to adding hostnames, you should use a data group. create data-group (reference in irule below as hostname-data-group) with a list of the hostnames you want redirected, and use an irule similar to:

when HTTP_REQUEST {
 if { class match [string tolower [HTTP::host]] equals hostname-data-group } {
  HTTP::redirect "https://mywebsite.com"
 }
}

Here's another options as well, really just comes down to how much data you got and how you want to manage it. Personally I like the second options Shaggy suggested.

when HTTP_REQUEST {
    set host [string tolower [HTTP::host]]
    switch $host {
        "site1.com" -
        "site2.com" -
        "www.site3.com" {
            HTTP::redirect "https://mywebsite.com"
        }
    }
}