Problem Statement

Every connected device around the world comes with a unique Media Access Control address, or a   MAC address. A common task a network administrator may come across is being able to identify a network device's manufacturer when given only a MAC address.

Interface with one (or numerous) APIs that exist on the internet and retrieve the device manufacturer based on a supplied MAC address. A MAC address that does not return a valid result should return the String "N/A".   An error related to the network connectivity or the API should return a null result. Many implementations on this page use http://api.macvendors.com/ which, as of 19th September 2021, is throttling requests. After only 2 calls, the following response is returned for all subsequent requests. If you are planning to use the same provider or going to run the examples on this page, consider building in a delay between two calls. {"errors":{"detail":"Too Many Requests","message":"Please slow down your requests or upgrade your plan at https://macvendors.com"}}

Let's start with the solution:

package require http

# finally is a bit like go's defer
proc finally args {
    tailcall trace add variable :#finally#: unset [list apply [list args $args]]
}

# basic wrapper for http::geturl
proc geturl {url} {
    set tok [::http::geturl $url]
    finally ::http::cleanup $tok
    ::http::data $tok
}   
proc maclookup {mac} {
    geturl http://api.macvendors.com/$mac
}

foreach mac {00-14-22-01-23-45 88:53:2E:67:07:BE} {
    puts "$mac\t[maclookup $mac]"
}