Feature: retry failed FTP URLs using passive mode

--- vcheck.orig	2005-03-20 20:05:19 +0100
+++ vcheck	2005-08-09 18:05:06 +0200
@@ -1435,6 +1436,7 @@
 sub read_url($;$$)  # &read_url $url [$outfile [$referrer]]
 {
   local($i, $t) = (1, time);
+  local($isftp) = (@_->[0] =~ m|^ftp://|i);
 
   sub meter($$$)
   {
@@ -1460,7 +1463,9 @@
     $xfersum += length $_;
     $_
   } else {
-    local $_ = $ua->request($req);
+    local $_;
+    delete $ENV{FTP_PASSIVE}; $_ = $ua->request($req);
+    $ENV{FTP_PASSIVE}=1;      $_ = $ua->request($req) if ($isftp and $_->{_headers}->{content-length} == 0);
     $xfersum += length($_->headers) + length $_->content;
     $_->content
   }