diff --git a/Makefile.am b/Makefile.am
index 6475978..fe74366 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -23,6 +23,7 @@ pkginclude_HEADERS = \
     include/igloo/interface.h \
     include/igloo/io.h \
     include/igloo/stdio.h \
+    include/igloo/filter.h \
     include/igloo/buffer.h \
     include/igloo/list.h \
     include/igloo/reportxml.h
@@ -33,6 +34,7 @@ libigloo_la_SOURCES = \
     src/ro.c \
     src/io.c \
     src/stdio.c \
+    src/filter.c \
     src/buffer.c \
     src/list.c \
     src/reportxml.c
diff --git a/include/igloo/filter.h b/include/igloo/filter.h
new file mode 100644
index 0000000..56c2542
--- /dev/null
+++ b/include/igloo/filter.h
@@ -0,0 +1,87 @@
+/* Copyright (C) 2019       Philipp "ph3-der-loewe" Schafft <lion@lion.leolix.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA  02110-1301, USA.
+ */
+
+#ifndef _LIBIGLOO__FILTER_H_
+#define _LIBIGLOO__FILTER_H_
+/**
+ * @file
+ * Put a good description of this file here
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "ro.h"
+#include "interface.h"
+
+/* About thread safety:
+ * This set of functions is thread safe.
+ */
+
+igloo_RO_FORWARD_TYPE(igloo_filter_t);
+
+/* Result of a test. */
+typedef enum {
+    /* The test resulted in an error condition. */
+    igloo_FILTER_RESULT_ERROR   = -1,
+    /* The object did not pass the test and should not be processed. */
+    igloo_FILTER_RESULT_DROP    =  0,
+    /* The object passed the test and should be processed. */
+    igloo_FILTER_RESULT_PASS    =  1
+} igloo_filter_result_t;
+
+/* Interface description */
+typedef struct {
+    igloo_interface_base_ifdesc_t __base;
+
+    /* Perform the actual test on the object.
+     * This must implement thread-safety itself if necessary.
+     */
+    igloo_filter_result_t (*test)(igloo_INTERFACE_BASIC_ARGS, igloo_ro_t object);
+} igloo_filter_ifdesc_t;
+
+/* This creates a new filter from a interface description and state.
+ * Parameters:
+ *  ifdesc
+ *      The interface description to use.
+ *  backend_object
+ *      A object used by the backend or igloo_RO_NULL.
+ *  backend_userdata
+ *      A userdata pointer used by the backend or NULL.
+ *  name, associated
+ *      See refobject_new().
+ */
+igloo_filter_t * igloo_filter_new(const igloo_filter_ifdesc_t *ifdesc, igloo_ro_t backend_object, void *backend_userdata, const char *name, igloo_ro_t associated);
+
+/* This tests a object according to the filter.
+ * Parameters:
+ *  filter
+ *      The filter to use.
+ *  object
+ *      The object to test.
+ * Returns:
+ *  Result of the test (error, drop, pass).
+ */
+igloo_filter_result_t igloo_filter_test(igloo_filter_t *filter, igloo_ro_t object);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ! _LIBIGLOO__FILTER_H_ */
diff --git a/include/igloo/types.h b/include/igloo/types.h
index 5a1e7c1..2e487c7 100644
--- a/include/igloo/types.h
+++ b/include/igloo/types.h
@@ -33,6 +33,7 @@ extern "C" {
 #include "typedef.h"
 
 typedef struct igloo_io_tag igloo_io_t;
+typedef struct igloo_filter_tag igloo_filter_t;
 typedef struct igloo_buffer_tag igloo_buffer_t;
 typedef struct igloo_list_tag igloo_list_t;
 
@@ -52,6 +53,7 @@ typedef union __attribute__ ((__transparent_union__)) {
     /* Those are libigloo's own types */
     igloo_RO_TYPE(igloo_ro_base_t)
     igloo_RO_TYPE(igloo_io_t)
+    igloo_RO_TYPE(igloo_filter_t)
     igloo_RO_TYPE(igloo_buffer_t)
     igloo_RO_TYPE(igloo_list_t)
     igloo_RO_TYPE(igloo_reportxml_t)
diff --git a/src/filter.c b/src/filter.c
new file mode 100644
index 0000000..0a4e923
--- /dev/null
+++ b/src/filter.c
@@ -0,0 +1,39 @@
+/* Icecast
+ *
+ * This program is distributed under the GNU General Public License, version 2.
+ * A copy of this license is included with this source.
+ *
+ * Copyright 2019,      Philipp "ph3-der-loewe" Schafft <lion@lion.leolix.org>,
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <igloo/ro.h>
+#include <igloo/filter.h>
+#include "private.h"
+
+struct igloo_filter_tag {
+    igloo_interface_base(filter)
+};
+
+igloo_RO_PUBLIC_TYPE(igloo_filter_t,
+        igloo_RO_TYPEDECL_FREE(igloo_interface_base_free)
+        );
+
+igloo_filter_t * igloo_filter_new(const igloo_filter_ifdesc_t *ifdesc, igloo_ro_t backend_object, void *backend_userdata, const char *name, igloo_ro_t associated)
+{
+    return igloo_interface_base_new(igloo_filter_t, ifdesc, backend_object, backend_userdata, name, associated);
+}
+
+igloo_filter_result_t igloo_filter_test(igloo_filter_t *filter, igloo_ro_t object)
+{
+    if (!filter)
+        return igloo_FILTER_RESULT_ERROR;
+
+    if (filter->ifdesc->test)
+        return filter->ifdesc->test(igloo_INTERFACE_BASIC_CALL(filter), object);
+
+    return igloo_FILTER_RESULT_ERROR;
+}