Just a small nit to pick with this line of code:

        ($ipentry,@domains)=split('\s{1,}|\t',$ligne);                
+                    # on "splitte" à un ou plusieurs espaces ou à une
+ tabulation
[download]

Your regular expression /\s{1,}|\t/, which can also be expressed as /[ \t\r\n\f]{1,}|\t/, says to match one or more whitespace characters (which includes the TAB character) or if that doesn't match then match a TAB character.

Your comment says that you want this regular expression: / {1,}|\t/ (or / +|\t/)