use LWP::UserAgent();
use HTTP::CookieJar::LWP();

## Create browser object.
my $jar = HTTP::CookieJar::LWP->new;
my $ua  = LWP::UserAgent->new(
    keep_alive=>200,
    cookie_jar => $jar,
    protocols_allowed => ['http', 'https'],
    timeout => 60,
);

my $client='xxx.xxx.xxx.xxx';
my $username='username';
my $password'password';
my $fw_file='/home/location/file.bin';
my $xsrf=auth($client, $username, $password); ##xsrf session token is provided by separate authentication sub.
my $results=upgrade($client, $fw_file);

sub upgrade {
    ## Upload file.
    my ($client,$fw_file)=@_;    
    my $res=$ua->post("http://$client/upload.cgi?xsrf=$xsrf", [
        'upfile' => ["$fw_file"],
        'Submit_button' => 'Upload+Software+Image',
        ],
        Content_Type => 'form-data',
    );
    ##Continues on to other steps from here.
    ##This post fails where it worked previously. 
}