$main_request = "http://cgi3.ebay.com/aw-cgi/eBayISAPI.dll?MfcISAPICommand=SignInWelcome&userid=userid&pass=pass&keepMeSignInOption=1&ru=";
$ru = "http://encode_this/";
# Encode $ru ?????
$main_request += $ru;

# Send $main_request