Item14150: Recompute validation keys on cached pages

Fix provided by MichaelDaum. Cached pages were keeping their original
cached validation keys.  Once they expired, it was impossible to submit
forms on cached pages without refreshing the cache.

core/lib/Foswiki/PageCache.pm

@@ -681,6 +681,14 @@ sub _handleDirtyArea {
         $prefs->popTopicContext();
     };
 
+    my $request = $session->{request};
+    my $context = $request->url( -full => 1, -path => 1, -query => 1 ) . time();
+    my $cgis    = $session->{users}->getCGISession();
+    my $usingStrikeOne = $Foswiki::cfg{Validation}{Method} eq 'strikeone';
+
+    $text =~
+s/<input type='hidden' name='validation_key' value='(\?.*?)' \/>/Foswiki::Validation::updateValidationKey($cgis, $context, $usingStrikeOne, $1)/gei;
+
     #Foswiki::Func::writeDebug("out text='$text'") if TRACE;
     return $text;
 }

core/lib/Foswiki/Validation.pm

@@ -92,6 +92,15 @@ sub addValidationKey {
     return "<input type='hidden' name='validation_key' value='?$nonce' />";
 }
 
+sub updateValidationKey {
+    my ( $cgis, $context, $strikeone, $oldKey ) = @_;
+
+    # expire old key
+    expireValidationKeys( $cgis, $oldKey );
+
+    return addValidationKey( $cgis, $context, $strikeone );
+}
+
 =begin TML
 
 ---++ StaticMethod generateValidationKey( $cgis, $context, $strikeone ) -> $nonce