I use a similar approach to toolic's suggestion, except I specifically target line endings and anchor the pattern:

    s/[\n\r]+$// for (@ip);
[download]

Most of the time, this is enough, because when I "export" text files to Ms Windows users, I use unix2dos to convert the line endings to MS Windows convention.

When I want or need a tool that robustly works under both MS Windows and Linux/Unix/POSIX, I would combine that with Eily's suggestion and add in ':raw' mode, like:

my @ip;
{  
  local $/ = "\n";
  open my $dat, "<:raw", $in_file or die "Can't open file $in_file: $!
+";
  @ip = <$dat>;
  s/[\n\r]+$// for (@ip);
  close $dat;
}
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(There's probably a module on CPAN that does this, and maybe even add support for legacy MacOS line endings.)