Index: uspace/srv/net/udp/meson.build
===================================================================
--- uspace/srv/net/udp/meson.build	(revision fc0de8c33fadd1f6730eb0465b89c7afa861fe56)
+++ uspace/srv/net/udp/meson.build	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
@@ -43,5 +43,7 @@
 test_src = files(
 	'test/assoc.c',
+	'test/msg.c',
 	'test/main.c',
+	'test/pdu.c',
 )
 
Index: uspace/srv/net/udp/test/main.c
===================================================================
--- uspace/srv/net/udp/test/main.c	(revision fc0de8c33fadd1f6730eb0465b89c7afa861fe56)
+++ uspace/srv/net/udp/test/main.c	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
@@ -32,4 +32,6 @@
 
 PCUT_IMPORT(assoc);
+PCUT_IMPORT(msg);
+PCUT_IMPORT(pdu);
 
 PCUT_MAIN();
Index: uspace/srv/net/udp/test/msg.c
===================================================================
--- uspace/srv/net/udp/test/msg.c	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
+++ uspace/srv/net/udp/test/msg.c	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2019 Jiri Svoboda
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <pcut/pcut.h>
+#include <str.h>
+#include "../msg.h"
+
+PCUT_INIT;
+
+PCUT_TEST_SUITE(msg);
+
+/** Test creating and deleting dummy message */
+PCUT_TEST(new_delete)
+{
+	udp_msg_t *msg;
+
+	msg = udp_msg_new();
+	udp_msg_delete(msg);
+}
+
+/** Test creating, filling in and deleting message */
+PCUT_TEST(new_fill_in_delete)
+{
+	udp_msg_t *msg;
+	const char *msgstr = "Hello";
+
+	msg = udp_msg_new();
+	PCUT_ASSERT_NOT_NULL(msg);
+	msg->data_size = str_size(msgstr) + 1;
+	msg->data = str_dup(msgstr);
+
+	udp_msg_delete(msg);
+}
+
+PCUT_EXPORT(msg);
Index: uspace/srv/net/udp/test/pdu.c
===================================================================
--- uspace/srv/net/udp/test/pdu.c	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
+++ uspace/srv/net/udp/test/pdu.c	(revision 46a8c3cd2588984cf4d1b909ed12113e2f780298)
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2019 Jiri Svoboda
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <inet/endpoint.h>
+#include <pcut/pcut.h>
+#include <str.h>
+#include "../msg.h"
+#include "../pdu.h"
+
+PCUT_INIT;
+
+PCUT_TEST_SUITE(pdu);
+
+/** Test creating and deleting dummy PDU */
+PCUT_TEST(new_delete)
+{
+	udp_pdu_t *pdu;
+
+	pdu = udp_pdu_new();
+	udp_pdu_delete(pdu);
+}
+
+/** Test encoding and decoding back IPv4 PDU */
+PCUT_TEST(encode_decode_v4)
+{
+	inet_ep2_t epp;
+	udp_msg_t *msg;
+	inet_ep2_t depp;
+	udp_msg_t *dmsg;
+	udp_pdu_t *pdu;
+	const char *msgstr = "Hello";
+	char *slocal, *sdlocal, *sremote, *sdremote;
+	errno_t rc;
+
+	inet_ep2_init(&epp);
+	inet_addr(&epp.local.addr, 192, 168, 0, 1);
+	epp.local.port = 1;
+	inet_addr(&epp.remote.addr, 192, 168, 0, 2);
+	epp.remote.port = 2;
+
+	msg = udp_msg_new();
+	PCUT_ASSERT_NOT_NULL(msg);
+	msg->data_size = str_size(msgstr) + 1;
+	msg->data = str_dup(msgstr);
+
+	rc = udp_pdu_encode(&epp, msg, &pdu);
+	PCUT_ASSERT_ERRNO_VAL(EOK, rc);
+	rc = udp_pdu_decode(pdu, &depp, &dmsg);
+	PCUT_ASSERT_ERRNO_VAL(EOK, rc);
+
+	/* Compare epp and depp. Local and remote should be swapped. */
+	PCUT_ASSERT_TRUE(inet_addr_compare(&epp.local.addr, &depp.remote.addr));
+	PCUT_ASSERT_EQUALS(epp.local.port, depp.remote.port);
+	PCUT_ASSERT_TRUE(inet_addr_compare(&epp.remote.addr, &depp.local.addr));
+	PCUT_ASSERT_EQUALS(epp.remote.port, depp.local.port);
+
+	/* Compare msg and dmsg */
+	PCUT_ASSERT_EQUALS(msg->data_size, dmsg->data_size);
+	PCUT_ASSERT_TRUE(memcmp(msg->data, dmsg->data, dmsg->data_size) == 0);
+
+	udp_pdu_delete(pdu);
+	udp_msg_delete(msg);
+	udp_msg_delete(dmsg);
+}
+
+PCUT_TEST(encode_decode_v6)
+{
+	inet_ep2_t epp;
+	udp_msg_t *msg;
+	inet_ep2_t depp;
+	udp_msg_t *dmsg;
+	udp_pdu_t *pdu;
+	const char *msgstr = "Hello";
+	errno_t rc;
+
+	inet_ep2_init(&epp);
+	inet_addr6(&epp.local.addr, 0xfc00, 0, 0, 0, 0, 0, 0, 1);
+	epp.local.port = 1;
+	inet_addr6(&epp.remote.addr, 0xfc00, 0, 0, 0, 0, 0, 0, 2);
+	epp.remote.port = 2;
+
+	msg = udp_msg_new();
+	PCUT_ASSERT_NOT_NULL(msg);
+	msg->data_size = str_size(msgstr) + 1;
+	msg->data = str_dup(msgstr);
+
+	rc = udp_pdu_encode(&epp, msg, &pdu);
+	PCUT_ASSERT_ERRNO_VAL(EOK, rc);
+	rc = udp_pdu_decode(pdu, &depp, &dmsg);
+	PCUT_ASSERT_ERRNO_VAL(EOK, rc);
+
+	/* Compare epp and depp. Local and remote should be swapped. */
+	PCUT_ASSERT_TRUE(inet_addr_compare(&epp.local.addr, &depp.remote.addr));
+	PCUT_ASSERT_EQUALS(epp.local.port, depp.remote.port);
+	PCUT_ASSERT_TRUE(inet_addr_compare(&epp.remote.addr, &depp.local.addr));
+	PCUT_ASSERT_EQUALS(epp.remote.port, depp.local.port);
+
+	/* Compare msg and dmsg */
+	PCUT_ASSERT_EQUALS(msg->data_size, dmsg->data_size);
+	PCUT_ASSERT_TRUE(memcmp(msg->data, dmsg->data, dmsg->data_size) == 0);
+
+	udp_pdu_delete(pdu);
+	udp_msg_delete(msg);
+	udp_msg_delete(dmsg);
+}
+
+PCUT_EXPORT(pdu);