tls: dtls initial implementation

Type: feature

Basic dtls transport protocol implementation that relies on openssl
wire protocol implementation. Retries/timeouts not yet supported.

To test using vcl test apps, first ensure all arp entries are properly
resolved and subsequently:

server: vcl_server -p dtls 1234
client: vcl_client -p dtls <server-ip> 1234 -U -N 2000000 -T 1460 -X

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I04b4516a8fe9ce85ba230bcdd891f33a900046ed

15 files changed, 751 insertions, 77 deletions

diff --git a/src/plugins/hs_apps/sapi/vpp_echo_common.c b/src/plugins/hs_apps/sapi/vpp_echo_common.c
index e24629b783e..02ce1686ea2 100644
--- a/src/plugins/hs_apps/sapi/vpp_echo_common.c
+++ b/src/plugins/hs_apps/sapi/vpp_echo_common.c
@@ -339,6 +339,9 @@ format_transport_proto (u8 * s, va_list * args)
     case TRANSPORT_PROTO_QUIC:
       s = format (s, "QUIC");
       break;
+    case TRANSPORT_PROTO_DTLS:
+      s = format (s, "DTLS");
+      break;
     default:
       s = format (s, "UNKNOWN");
       break;
diff --git a/src/plugins/hs_apps/vcl/vcl_test_client.c b/src/plugins/hs_apps/vcl/vcl_test_client.c
index 0aff98ef1dd..35f1ac11818 100644
--- a/src/plugins/hs_apps/vcl/vcl_test_client.c
+++ b/src/plugins/hs_apps/vcl/vcl_test_client.c
@@ -1105,7 +1105,8 @@ main (int argc, char **argv)
   if (ctrl->fd < 0)
     vtfail ("vppcom_session_create()", ctrl->fd);
 
-  if (vcm->proto == VPPCOM_PROTO_TLS || vcm->proto == VPPCOM_PROTO_QUIC)
+  if (vcm->proto == VPPCOM_PROTO_TLS || vcm->proto == VPPCOM_PROTO_QUIC ||
+      vcm->proto == VPPCOM_PROTO_DTLS)
     {
       vppcom_cert_key_pair_t ckpair;
       uint32_t ckp_len;
diff --git a/src/plugins/hs_apps/vcl/vcl_test_server.c b/src/plugins/hs_apps/vcl/vcl_test_server.c
index a2a4d6ac3b0..b4966bf168b 100644
--- a/src/plugins/hs_apps/vcl/vcl_test_server.c
+++ b/src/plugins/hs_apps/vcl/vcl_test_server.c
@@ -550,8 +550,9 @@ vts_worker_init (vcl_test_server_worker_t * wrk)
       vppcom_session_attr (wrk->listen_fd, VPPCOM_ATTR_SET_CONNECTED, 0, 0);
     }
 
-  if (vsm->cfg.proto == VPPCOM_PROTO_TLS
-      || vsm->cfg.proto == VPPCOM_PROTO_QUIC)
+  if (vsm->cfg.proto == VPPCOM_PROTO_TLS ||
+      vsm->cfg.proto == VPPCOM_PROTO_QUIC ||
+      vsm->cfg.proto == VPPCOM_PROTO_DTLS)
     {
       vppcom_cert_key_pair_t ckpair;
       uint32_t ckp_len;
diff --git a/src/plugins/tlsopenssl/CMakeLists.txt b/src/plugins/tlsopenssl/CMakeLists.txt
index 61d3638a39a..eb67e4cceaf 100644
--- a/src/plugins/tlsopenssl/CMakeLists.txt
+++ b/src/plugins/tlsopenssl/CMakeLists.txt
@@ -20,6 +20,7 @@ if(OPENSSL_FOUND AND OPENSSL_VERSION VERSION_GREATER_EQUAL "1.1.0")
     tls_openssl.c
     tls_openssl_api.c
     tls_async.c
+    dtls_bio.c
 
     API_FILES
     tls_openssl.api
diff --git a/src/plugins/tlsopenssl/dtls_bio.c b/src/plugins/tlsopenssl/dtls_bio.c
new file mode 100644
index 00000000000..7cd2abd42e2
--- /dev/null
+++ b/src/plugins/tlsopenssl/dtls_bio.c
@@ -0,0 +1,225 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <openssl/bio.h>
+#include <openssl/err.h>
+
+#include <vnet/session/session.h>
+#include <vnet/session/application_interface.h>
+
+static inline session_t *
+bio_session (BIO *bio)
+{
+  return session_get_from_handle (pointer_to_uword (BIO_get_data (bio)));
+}
+
+static int
+bio_dtls_alloc (BIO *bio)
+{
+  BIO_set_init (bio, 0);
+  BIO_set_data (bio, 0);
+  BIO_set_flags (bio, 0);
+  BIO_set_shutdown (bio, 0);
+  return 1;
+}
+
+static int
+bio_dtls_free (BIO *bio)
+{
+  if (!bio)
+    return 0;
+
+  if (BIO_get_shutdown (bio))
+    {
+      if (BIO_get_init (bio))
+	session_close (bio_session (bio));
+      BIO_set_init (bio, 0);
+      BIO_set_flags (bio, 0);
+    }
+  return 1;
+}
+
+static int
+bio_dtls_read (BIO *b, char *out, int outl)
+{
+  app_session_transport_t at;
+  session_t *s;
+  int rv;
+
+  if (PREDICT_FALSE (!out))
+    return 0;
+
+  s = bio_session (b);
+  if (!s)
+    {
+      clib_warning ("no session");
+      errno = EBADFD;
+      return -1;
+    }
+
+  rv = app_recv_dgram_raw (s->rx_fifo, (u8 *) out, outl, &at,
+			   0 /* clear evt */, 0 /* peek */);
+
+  if (rv < 0)
+    {
+      BIO_set_retry_read (b);
+      errno = EAGAIN;
+      return -1;
+    }
+
+  if (svm_fifo_is_empty_cons (s->rx_fifo))
+    svm_fifo_unset_event (s->rx_fifo);
+
+  BIO_clear_retry_flags (b);
+
+  return rv;
+}
+
+static int
+bio_dtls_write (BIO *b, const char *in, int inl)
+{
+  app_session_transport_t at = { 0 };
+  svm_msg_q_t *mq;
+  session_t *s;
+  int rv;
+
+  if (PREDICT_FALSE (!in))
+    return 0;
+
+  s = bio_session (b);
+  if (!s)
+    {
+      clib_warning ("no session");
+      errno = EBADFD;
+      return -1;
+    }
+
+  mq = session_main_get_vpp_event_queue (s->thread_index);
+  rv = app_send_dgram_raw (s->tx_fifo, &at, mq, (u8 *) in, inl,
+			   SESSION_IO_EVT_TX, 1 /* do_evt */, 0 /* noblock */);
+
+  if (rv < 0)
+    {
+      BIO_set_retry_read (b);
+      errno = EAGAIN;
+      return -1;
+    }
+
+  BIO_clear_retry_flags (b);
+
+  return rv;
+}
+
+static int
+dtls_dgram_overhead (BIO *b)
+{
+  session_t *s = bio_session (b);
+  if (session_type_is_ip4 (s->session_type))
+    /* 20B ip 8B udp */
+    return 28;
+  else
+    /* 40B ip 8B udp */
+    return 48;
+}
+
+static u16
+dtls_dgram_mss (BIO *b)
+{
+  session_t *s = bio_session (b);
+  transport_send_params_t sp;
+
+  transport_connection_snd_params (session_get_transport (s), &sp);
+
+  return sp.snd_mss;
+}
+
+long
+bio_dtls_ctrl (BIO *b, int cmd, long larg, void *parg)
+{
+  long ret = 1;
+
+  switch (cmd)
+    {
+    case BIO_C_SET_FD:
+      os_panic ();
+      break;
+    case BIO_C_GET_FD:
+      os_panic ();
+      break;
+    case BIO_CTRL_GET_CLOSE:
+      ret = BIO_get_shutdown (b);
+      break;
+    case BIO_CTRL_SET_CLOSE:
+      BIO_set_shutdown (b, (int) larg);
+      break;
+    case BIO_CTRL_PENDING:
+    case BIO_CTRL_WPENDING:
+      ret = 0;
+      break;
+    case BIO_CTRL_DUP:
+    case BIO_CTRL_FLUSH:
+      ret = 1;
+      break;
+    case BIO_CTRL_DGRAM_QUERY_MTU:
+      ret = dtls_dgram_mss (b);
+      break;
+    case BIO_CTRL_DGRAM_SET_MTU:
+      ret = 0;
+      break;
+    case BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT:
+      ret = 0;
+      break;
+    case BIO_CTRL_DGRAM_GET_MTU_OVERHEAD:
+      ret = dtls_dgram_overhead (b);
+      break;
+    default:
+      ret = 0;
+      break;
+    }
+  return ret;
+}
+
+BIO *
+BIO_new_dtls (session_handle_t sh)
+{
+  static BIO_METHOD *dtls_bio_method;
+  BIO *b;
+
+  if (!dtls_bio_method)
+    {
+      dtls_bio_method = BIO_meth_new (BIO_TYPE_SOCKET, "dtls_bio");
+      BIO_meth_set_write (dtls_bio_method, bio_dtls_write);
+      BIO_meth_set_read (dtls_bio_method, bio_dtls_read);
+      BIO_meth_set_create (dtls_bio_method, bio_dtls_alloc);
+      BIO_meth_set_destroy (dtls_bio_method, bio_dtls_free);
+      BIO_meth_set_ctrl (dtls_bio_method, bio_dtls_ctrl);
+    }
+
+  b = BIO_new (dtls_bio_method);
+
+  /* Initialize the BIO */
+  BIO_set_data (b, uword_to_pointer (sh, void *));
+  BIO_set_init (b, 1);
+
+  return b;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/tlsopenssl/tls_bio.h b/src/plugins/tlsopenssl/tls_bios.h
index b9f3c5384b9..259900ef754 100644
--- a/src/plugins/tlsopenssl/tls_bio.h
+++ b/src/plugins/tlsopenssl/tls_bios.h
@@ -19,6 +19,7 @@
 #include <vnet/session/session_types.h>
 
 BIO *BIO_new_tls (session_handle_t sh);
+BIO *BIO_new_dtls (session_handle_t sh);
 
 #endif /* SRC_PLUGINS_TLSOPENSSL_TLS_BIO_H_ */
 
diff --git a/src/plugins/tlsopenssl/tls_openssl.c b/src/plugins/tlsopenssl/tls_openssl.c
index 789c64d88d3..00cd4621897 100644
--- a/src/plugins/tlsopenssl/tls_openssl.c
+++ b/src/plugins/tlsopenssl/tls_openssl.c
@@ -26,19 +26,19 @@
 #include <vnet/tls/tls.h>
 #include <ctype.h>
 #include <tlsopenssl/tls_openssl.h>
-#include <tlsopenssl/tls_bio.h>
+#include <tlsopenssl/tls_bios.h>
 
 #define MAX_CRYPTO_LEN 64
 
 openssl_main_t openssl_main;
+
 static u32
-openssl_ctx_alloc (void)
+openssl_ctx_alloc_w_thread (u32 thread_index)
 {
-  u8 thread_index = vlib_get_thread_index ();
-  openssl_main_t *tm = &openssl_main;
+  openssl_main_t *om = &openssl_main;
   openssl_ctx_t **ctx;
 
-  pool_get (tm->ctx_pool[thread_index], ctx);
+  pool_get (om->ctx_pool[thread_index], ctx);
   if (!(*ctx))
     *ctx = clib_mem_alloc (sizeof (openssl_ctx_t));
 
@@ -46,10 +46,16 @@ openssl_ctx_alloc (void)
   (*ctx)->ctx.c_thread_index = thread_index;
   (*ctx)->ctx.tls_ctx_engine = CRYPTO_ENGINE_OPENSSL;
   (*ctx)->ctx.app_session_handle = SESSION_INVALID_HANDLE;
-  (*ctx)->openssl_ctx_index = ctx - tm->ctx_pool[thread_index];
+  (*ctx)->openssl_ctx_index = ctx - om->ctx_pool[thread_index];
   return ((*ctx)->openssl_ctx_index);
 }
 
+static u32
+openssl_ctx_alloc (void)
+{
+  return openssl_ctx_alloc_w_thread (vlib_get_thread_index ());
+}
+
 static void
 openssl_ctx_free (tls_ctx_t * ctx)
 {
@@ -68,6 +74,40 @@ openssl_ctx_free (tls_ctx_t * ctx)
 		  oc->openssl_ctx_index);
 }
 
+static void *
+openssl_ctx_detach (tls_ctx_t *ctx)
+{
+  openssl_ctx_t *oc = (openssl_ctx_t *) ctx, *oc_copy;
+
+  oc_copy = clib_mem_alloc (sizeof (*oc_copy));
+  clib_memcpy (oc_copy, oc, sizeof (*oc));
+
+  return oc_copy;
+}
+
+static u32
+openssl_ctx_attach (u32 thread_index, void *ctx_ptr)
+{
+  openssl_main_t *om = &openssl_main;
+  session_handle_t sh;
+  openssl_ctx_t **oc;
+
+  pool_get (om->ctx_pool[thread_index], oc);
+  /* Free the old instance instead of looking for an empty spot */
+  if (*oc)
+    clib_mem_free (*oc);
+
+  *oc = ctx_ptr;
+  (*oc)->openssl_ctx_index = oc - om->ctx_pool[thread_index];
+  (*oc)->ctx.c_thread_index = thread_index;
+
+  sh = (*oc)->ctx.tls_session_handle;
+  BIO_set_data ((*oc)->rbio, uword_to_pointer (sh, void *));
+  BIO_set_data ((*oc)->wbio, uword_to_pointer (sh, void *));
+
+  return ((*oc)->openssl_ctx_index);
+}
+
 tls_ctx_t *
 openssl_ctx_get (u32 ctx_index)
 {
@@ -310,9 +350,9 @@ openssl_confirm_app_close (tls_ctx_t * ctx)
   session_transport_closed_notify (&ctx->connection);
 }
 
-static inline int
-openssl_ctx_write (tls_ctx_t * ctx, session_t * app_session,
-		   transport_send_params_t * sp)
+static int
+openssl_ctx_write_tls (tls_ctx_t *ctx, session_t *app_session,
+		       transport_send_params_t *sp)
 {
   openssl_ctx_t *oc = (openssl_ctx_t *) ctx;
   u32 deq_max, space, enq_buf;
@@ -358,8 +398,77 @@ check_tls_fifo:
   return wrote;
 }
 
+static int
+openssl_ctx_write_dtls (tls_ctx_t *ctx, session_t *app_session,
+			transport_send_params_t *sp)
+{
+  openssl_main_t *om = &openssl_main;
+  openssl_ctx_t *oc = (openssl_ctx_t *) ctx;
+  session_dgram_pre_hdr_t hdr;
+  session_t *us;
+  int wrote, rv;
+  u32 read = 0, to_deq, dgram_sz;
+  u8 *buf;
+
+  us = session_get_from_handle (ctx->tls_session_handle);
+  to_deq = svm_fifo_max_dequeue_cons (app_session->tx_fifo);
+  buf = om->tx_bufs[ctx->c_thread_index];
+
+  while (to_deq > 0)
+    {
+      /* Peeking only pre-header dgram because the session is connected */
+      rv = svm_fifo_peek (app_session->tx_fifo, 0, sizeof (hdr), (u8 *) &hdr);
+      ASSERT (rv == sizeof (hdr) && hdr.data_length < vec_len (buf));
+      ASSERT (to_deq >= hdr.data_length + SESSION_CONN_HDR_LEN);
+
+      dgram_sz = hdr.data_length + SESSION_CONN_HDR_LEN;
+      if (svm_fifo_max_enqueue_prod (us->tx_fifo) < dgram_sz + TLSO_CTRL_BYTES)
+	{
+	  svm_fifo_add_want_deq_ntf (us->tx_fifo, SVM_FIFO_WANT_DEQ_NOTIF);
+	  transport_connection_deschedule (&ctx->connection);
+	  sp->flags |= TRANSPORT_SND_F_DESCHED;
+	  goto done;
+	}
+
+      rv = svm_fifo_peek (app_session->tx_fifo, SESSION_CONN_HDR_LEN,
+			  hdr.data_length, buf);
+      ASSERT (rv == hdr.data_length);
+      svm_fifo_dequeue_drop (app_session->tx_fifo, dgram_sz);
+
+      wrote = SSL_write (oc->ssl, buf, rv);
+      ASSERT (wrote > 0);
+
+      read += rv;
+      to_deq -= dgram_sz;
+    }
+
+done:
+
+  if (svm_fifo_needs_deq_ntf (app_session->tx_fifo, read))
+    session_dequeue_notify (app_session);
+
+  if (read)
+    tls_add_vpp_q_tx_evt (us);
+
+  if (PREDICT_FALSE (ctx->app_closed &&
+		     !svm_fifo_max_enqueue_prod (us->rx_fifo)))
+    openssl_confirm_app_close (ctx);
+
+  return read;
+}
+
+static inline int
+openssl_ctx_write (tls_ctx_t *ctx, session_t *app_session,
+		   transport_send_params_t *sp)
+{
+  if (ctx->tls_type == TRANSPORT_PROTO_TLS)
+    return openssl_ctx_write_tls (ctx, app_session, sp);
+  else
+    return openssl_ctx_write_dtls (ctx, app_session, sp);
+}
+
 static inline int
-openssl_ctx_read (tls_ctx_t * ctx, session_t * tls_session)
+openssl_ctx_read_tls (tls_ctx_t *ctx, session_t *tls_session)
 {
   openssl_ctx_t *oc = (openssl_ctx_t *) ctx;
   session_t *app_session;
@@ -387,6 +496,76 @@ openssl_ctx_read (tls_ctx_t * ctx, session_t * tls_session)
   return wrote;
 }
 
+static inline int
+openssl_ctx_read_dtls (tls_ctx_t *ctx, session_t *us)
+{
+  openssl_main_t *om = &openssl_main;
+  openssl_ctx_t *oc = (openssl_ctx_t *) ctx;
+  session_dgram_hdr_t hdr;
+  session_t *app_session;
+  u32 wrote = 0;
+  int read, rv;
+  u8 *buf;
+
+  if (PREDICT_FALSE (SSL_in_init (oc->ssl)))
+    {
+      u32 us_index = us->session_index;
+      if (openssl_ctx_handshake_rx (ctx, us) < 0)
+	return 0;
+      /* Session pool might grow when allocating the app's session */
+      us = session_get (us_index, ctx->c_thread_index);
+    }
+
+  buf = om->rx_bufs[ctx->c_thread_index];
+  app_session = session_get_from_handle (ctx->app_session_handle);
+  svm_fifo_fill_chunk_list (app_session->rx_fifo);
+
+  while (svm_fifo_max_dequeue_cons (us->rx_fifo) > 0)
+    {
+      if (svm_fifo_max_enqueue_prod (app_session->rx_fifo) < DTLSO_MAX_DGRAM)
+	{
+	  tls_add_vpp_q_builtin_rx_evt (us);
+	  goto done;
+	}
+
+      read = SSL_read (oc->ssl, buf, vec_len (buf));
+      if (PREDICT_FALSE (read <= 0))
+	{
+	  if (read < 0)
+	    tls_add_vpp_q_builtin_rx_evt (us);
+	  goto done;
+	}
+      wrote += read;
+
+      hdr.data_length = read;
+      hdr.data_offset = 0;
+
+      svm_fifo_seg_t segs[2] = { { (u8 *) &hdr, sizeof (hdr) },
+				 { buf, read } };
+
+      rv = svm_fifo_enqueue_segments (app_session->rx_fifo, segs, 2,
+				      0 /* allow partial */);
+      ASSERT (rv > 0);
+    }
+
+done:
+
+  /* If handshake just completed, session may still be in accepting state */
+  if (app_session->session_state >= SESSION_STATE_READY)
+    tls_notify_app_enqueue (ctx, app_session);
+
+  return wrote;
+}
+
+static inline int
+openssl_ctx_read (tls_ctx_t *ctx, session_t *ts)
+{
+  if (ctx->tls_type == TRANSPORT_PROTO_TLS)
+    return openssl_ctx_read_tls (ctx, ts);
+  else
+    return openssl_ctx_read_dtls (ctx, ts);
+}
+
 static int
 openssl_ctx_init_client (tls_ctx_t * ctx)
 {
@@ -396,10 +575,11 @@ openssl_ctx_init_client (tls_ctx_t * ctx)
   const SSL_METHOD *method;
   int rv, err;
 
-  method = SSLv23_client_method ();
+  method = ctx->tls_type == TRANSPORT_PROTO_TLS ? SSLv23_client_method () :
+						  DTLS_client_method ();
   if (method == NULL)
     {
-      TLS_DBG (1, "SSLv23_method returned null");
+      TLS_DBG (1, "(D)TLS_method returned null");
       return -1;
     }
 
@@ -433,8 +613,16 @@ openssl_ctx_init_client (tls_ctx_t * ctx)
       return -1;
     }
 
-  oc->rbio = BIO_new_tls (ctx->tls_session_handle);
-  oc->wbio = BIO_new_tls (ctx->tls_session_handle);
+  if (ctx->tls_type == TRANSPORT_PROTO_TLS)
+    {
+      oc->rbio = BIO_new_tls (ctx->tls_session_handle);
+      oc->wbio = BIO_new_tls (ctx->tls_session_handle);
+    }
+  else
+    {
+      oc->rbio = BIO_new_dtls (ctx->tls_session_handle);
+      oc->wbio = BIO_new_dtls (ctx->tls_session_handle);
+    }
 
   SSL_set_bio (oc->ssl, oc->wbio, oc->rbio);
   SSL_set_connect_state (oc->ssl);
@@ -504,7 +692,8 @@ openssl_start_listen (tls_ctx_t * lctx)
       return -1;
     }
 
-  method = SSLv23_method ();
+  method = lctx->tls_type == TRANSPORT_PROTO_TLS ? SSLv23_server_method () :
+						   DTLS_server_method ();
   ssl_ctx = SSL_CTX_new (method);
   if (!ssl_ctx)
     {
@@ -604,8 +793,16 @@ openssl_ctx_init_server (tls_ctx_t * ctx)
       return -1;
     }
 
-  oc->rbio = BIO_new_tls (ctx->tls_session_handle);
-  oc->wbio = BIO_new_tls (ctx->tls_session_handle);
+  if (ctx->tls_type == TRANSPORT_PROTO_TLS)
+    {
+      oc->rbio = BIO_new_tls (ctx->tls_session_handle);
+      oc->wbio = BIO_new_tls (ctx->tls_session_handle);
+    }
+  else
+    {
+      oc->rbio = BIO_new_dtls (ctx->tls_session_handle);
+      oc->wbio = BIO_new_dtls (ctx->tls_session_handle);
+    }
 
   SSL_set_bio (oc->ssl, oc->wbio, oc->rbio);
   SSL_set_accept_state (oc->ssl);
@@ -682,7 +879,10 @@ openssl_app_close (tls_ctx_t * ctx)
 
 const static tls_engine_vft_t openssl_engine = {
   .ctx_alloc = openssl_ctx_alloc,
+  .ctx_alloc_w_thread = openssl_ctx_alloc_w_thread,
   .ctx_free = openssl_ctx_free,
+  .ctx_attach = openssl_ctx_attach,
+  .ctx_detach = openssl_ctx_detach,
   .ctx_get = openssl_ctx_get,
   .ctx_get_w_thread = openssl_ctx_get_w_thread,
   .ctx_init_server = openssl_ctx_init_server,
@@ -771,7 +971,7 @@ tls_openssl_init (vlib_main_t * vm)
   vlib_thread_main_t *vtm = vlib_get_thread_main ();
   openssl_main_t *om = &openssl_main;
   clib_error_t *error = 0;
-  u32 num_threads;
+  u32 num_threads, i;
 
   error = tls_openssl_api_init (vm);
   num_threads = 1 /* main thread */  + vtm->n_threads;
@@ -786,7 +986,13 @@ tls_openssl_init (vlib_main_t * vm)
     }
 
   vec_validate (om->ctx_pool, num_threads - 1);
-
+  vec_validate (om->rx_bufs, num_threads - 1);
+  vec_validate (om->tx_bufs, num_threads - 1);
+  for (i = 0; i < num_threads; i++)
+    {
+      vec_validate (om->rx_bufs[i], DTLSO_MAX_DGRAM);
+      vec_validate (om->tx_bufs[i], DTLSO_MAX_DGRAM);
+    }
   tls_register_engine (&openssl_engine, CRYPTO_ENGINE_OPENSSL);
 
   om->engine_init = 0;
diff --git a/src/plugins/tlsopenssl/tls_openssl.h b/src/plugins/tlsopenssl/tls_openssl.h
index 16b256d0ceb..a4beecc8ec1 100644
--- a/src/plugins/tlsopenssl/tls_openssl.h
+++ b/src/plugins/tlsopenssl/tls_openssl.h
@@ -13,6 +13,9 @@
  * limitations under the License.
  */
 
+#ifndef SRC_PLUGINS_TLSOPENSSL_TLS_OPENSSL_H_
+#define SRC_PLUGINS_TLSOPENSSL_TLS_OPENSSL_H_
+
 #include <openssl/ssl.h>
 #include <openssl/conf.h>
 #include <openssl/err.h>
@@ -24,6 +27,8 @@
 #define TLSO_CTRL_BYTES 1000
 #define TLSO_MIN_ENQ_SPACE (1 << 16)
 
+#define DTLSO_MAX_DGRAM 2000
+
 typedef struct tls_ctx_openssl_
 {
   tls_ctx_t ctx;			/**< First */
@@ -48,6 +53,9 @@ typedef struct openssl_main_
   openssl_ctx_t ***ctx_pool;
   openssl_listen_ctx_t *lctx_pool;
 
+  u8 **rx_bufs;
+  u8 **tx_bufs;
+
   /* API message ID base */
   u16 msg_id_base;
 
@@ -73,6 +81,8 @@ clib_error_t *tls_openssl_api_init (vlib_main_t * vm);
 int tls_openssl_set_ciphers (char *ciphers);
 int vpp_openssl_is_inflight (tls_ctx_t * ctx);
 
+#endif /* SRC_PLUGINS_TLSOPENSSL_TLS_OPENSSL_H_ */
+
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/vcl/vcl_private.h b/src/vcl/vcl_private.h
index 21853ebdc9a..59bb7621e70 100644
--- a/src/vcl/vcl_private.h
+++ b/src/vcl/vcl_private.h
@@ -542,7 +542,8 @@ static inline u8
 vcl_session_has_crypto (vcl_session_t *s)
 {
   return (s->session_type == VPPCOM_PROTO_TLS ||
-	  s->session_type == VPPCOM_PROTO_QUIC);
+	  s->session_type == VPPCOM_PROTO_QUIC ||
+	  s->session_type == VPPCOM_PROTO_DTLS);
 }
 
 static inline u8
@@ -608,7 +609,7 @@ vcl_ip_copy_to_ep (ip46_address_t * ip, vppcom_endpt_t * ep, u8 is_ip4)
 static inline int
 vcl_proto_is_dgram (uint8_t proto)
 {
-  return proto == VPPCOM_PROTO_UDP;
+  return proto == VPPCOM_PROTO_UDP || proto == VPPCOM_PROTO_DTLS;
 }
 
 static inline u8
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 21892438c37..bc83b55d5d0 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -1526,6 +1526,10 @@ vppcom_unformat_proto (uint8_t * proto, char *proto_str)
     *proto = VPPCOM_PROTO_QUIC;
   else if (!strcmp (proto_str, "quic"))
     *proto = VPPCOM_PROTO_QUIC;
+  else if (!strcmp (proto_str, "DTLS"))
+    *proto = VPPCOM_PROTO_DTLS;
+  else if (!strcmp (proto_str, "dtls"))
+    *proto = VPPCOM_PROTO_DTLS;
   else
     return 1;
   return 0;
@@ -3933,6 +3937,9 @@ vppcom_proto_str (vppcom_proto_t proto)
     case VPPCOM_PROTO_QUIC:
       proto_str = "QUIC";
       break;
+    case VPPCOM_PROTO_DTLS:
+      proto_str = "DTLS";
+      break;
     default:
       proto_str = "UNKNOWN";
       break;
diff --git a/src/vcl/vppcom.h b/src/vcl/vppcom.h
index 6e3c2784db6..1d2fa5df1ba 100644
--- a/src/vcl/vppcom.h
+++ b/src/vcl/vppcom.h
@@ -45,29 +45,30 @@ extern "C"
 #define VPPCOM_ENV_VPP_API_SOCKET           	"VCL_VPP_API_SOCKET"
 #define VPPCOM_ENV_VPP_SAPI_SOCKET		"VCL_VPP_SAPI_SOCKET"
 
-typedef enum
-{
-  VPPCOM_PROTO_TCP = 0,
-  VPPCOM_PROTO_UDP,
-  VPPCOM_PROTO_NONE,
-  VPPCOM_PROTO_TLS,
-  VPPCOM_PROTO_QUIC,
-} vppcom_proto_t;
-
-typedef enum
-{
-  VPPCOM_IS_IP6 = 0,
-  VPPCOM_IS_IP4,
-} vppcom_is_ip4_t;
-
-typedef struct vppcom_endpt_t_
-{
-  uint8_t is_cut_thru;
-  uint8_t is_ip4;
-  uint8_t *ip;
-  uint16_t port;
-  uint64_t parent_handle;
-} vppcom_endpt_t;
+  typedef enum
+  {
+    VPPCOM_PROTO_TCP = 0,
+    VPPCOM_PROTO_UDP,
+    VPPCOM_PROTO_NONE,
+    VPPCOM_PROTO_TLS,
+    VPPCOM_PROTO_QUIC,
+    VPPCOM_PROTO_DTLS,
+  } vppcom_proto_t;
+
+  typedef enum
+  {
+    VPPCOM_IS_IP6 = 0,
+    VPPCOM_IS_IP4,
+  } vppcom_is_ip4_t;
+
+  typedef struct vppcom_endpt_t_
+  {
+    uint8_t is_cut_thru;
+    uint8_t is_ip4;
+    uint8_t *ip;
+    uint16_t port;
+    uint64_t parent_handle;
+  } vppcom_endpt_t;
 
 typedef uint32_t vcl_session_handle_t;
 
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index 169cca5efe8..85a802c3a06 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -1825,7 +1825,7 @@ session_main_init (vlib_main_t * vm)
   smm->evt_qs_segment_size = 1 << 20;
 #endif
 
-  smm->last_transport_proto_type = TRANSPORT_PROTO_QUIC;
+  smm->last_transport_proto_type = TRANSPORT_PROTO_DTLS;
 
   return 0;
 }
diff --git a/src/vnet/session/transport_types.h b/src/vnet/session/transport_types.h
index 2caafea0fbe..1e7d5672f1c 100644
--- a/src/vnet/session/transport_types.h
+++ b/src/vnet/session/transport_types.h
@@ -158,12 +158,13 @@ STATIC_ASSERT (STRUCT_OFFSET_OF (transport_connection_t, s_index)
 STATIC_ASSERT (sizeof (transport_connection_t) <= 128,
 	       "moved into 3rd cache line");
 
-#define foreach_transport_proto				\
-  _(TCP, "tcp", "T")					\
-  _(UDP, "udp", "U")					\
-  _(NONE, "ct", "C")					\
-  _(TLS, "tls", "J")					\
-  _(QUIC, "quic", "Q")					\
+#define foreach_transport_proto                                               \
+  _ (TCP, "tcp", "T")                                                         \
+  _ (UDP, "udp", "U")                                                         \
+  _ (NONE, "ct", "C")                                                         \
+  _ (TLS, "tls", "J")                                                         \
+  _ (QUIC, "quic", "Q")                                                       \
+  _ (DTLS, "dtls", "D")
 
 typedef enum _transport_proto
 {
diff --git a/src/vnet/tls/tls.c b/src/vnet/tls/tls.c
index 59dae88fd1f..6052ca1bf65 100644
--- a/src/vnet/tls/tls.c
+++ b/src/vnet/tls/tls.c
@@ -221,13 +221,32 @@ tls_notify_app_connected (tls_ctx_t * ctx, session_error_t err)
     }
 
   if (err)
-    goto failed;
+    {
+      /* Free app session pre-allocated when transport was established */
+      if (ctx->tls_type == TRANSPORT_PROTO_TLS)
+	session_free (session_get (ctx->c_s_index, ctx->c_thread_index));
+      goto failed;
+    }
+
+  /* For DTLS the app session is not preallocated because the underlying udp
+   * session might migrate to a different worker during the handshake */
+  if (ctx->tls_type == TRANSPORT_PROTO_DTLS)
+    {
+      session_type_t st;
+      app_session = session_alloc (ctx->c_thread_index);
+      app_session->session_state = SESSION_STATE_CREATED;
+      ctx->c_s_index = app_session->session_index;
+      st =
+	session_type_from_proto_and_ip (TRANSPORT_PROTO_DTLS, ctx->tcp_is_ip4);
+      app_session->session_type = st;
+      app_session->connection_index = ctx->tls_ctx_handle;
+    }
+  else
+    {
+      app_session = session_get (ctx->c_s_index, ctx->c_thread_index);
+    }
 
-  app_session = session_get (ctx->c_s_index, ctx->c_thread_index);
   app_session->app_wrk_index = ctx->parent_app_wrk_index;
-  app_session->connection_index = ctx->tls_ctx_handle;
-  app_session->session_type =
-    session_type_from_proto_and_ip (TRANSPORT_PROTO_TLS, ctx->tcp_is_ip4);
 
   if ((err = app_worker_init_connected (app_wrk, app_session)))
     goto failed;
@@ -247,8 +266,6 @@ tls_notify_app_connected (tls_ctx_t * ctx, session_error_t err)
   return 0;
 
 failed:
-  /* Free app session pre-allocated when transport was established */
-  session_free (session_get (ctx->c_s_index, ctx->c_thread_index));
   ctx->no_app_session = 1;
   tls_disconnect (ctx->tls_ctx_handle, vlib_get_thread_index ());
   return app_worker_connect_notify (app_wrk, 0, err,
@@ -278,6 +295,28 @@ tls_ctx_alloc (crypto_engine_type_t engine_type)
   return (((u32) engine_type << TLS_ENGINE_TYPE_SHIFT) | ctx_index);
 }
 
+static inline u32
+tls_ctx_alloc_w_thread (crypto_engine_type_t engine_type, u32 thread_index)
+{
+  u32 ctx_index;
+  ctx_index = tls_vfts[engine_type].ctx_alloc_w_thread (thread_index);
+  return (((u32) engine_type << TLS_ENGINE_TYPE_SHIFT) | ctx_index);
+}
+
+static inline u32
+tls_ctx_attach (crypto_engine_type_t engine_type, u32 thread_index, void *ctx)
+{
+  u32 ctx_index;
+  ctx_index = tls_vfts[engine_type].ctx_attach (thread_index, ctx);
+  return (((u32) engine_type << TLS_ENGINE_TYPE_SHIFT) | ctx_index);
+}
+
+static inline void *
+tls_ctx_detach (tls_ctx_t *ctx)
+{
+  return tls_vfts[ctx->tls_ctx_engine].ctx_detach (ctx);
+}
+
 static inline tls_ctx_t *
 tls_ctx_get (u32 ctx_handle)
 {
@@ -442,6 +481,10 @@ tls_app_rx_callback (session_t * tls_session)
 {
   tls_ctx_t *ctx;
 
+  /* DTLS session migrating, wait for next notification */
+  if (PREDICT_FALSE (tls_session->flags & SESSION_F_IS_MIGRATING))
+    return 0;
+
   ctx = tls_ctx_get (tls_session->opaque);
   tls_ctx_read (ctx, tls_session);
   return 0;
@@ -459,11 +502,12 @@ tls_app_tx_callback (session_t * tls_session)
 }
 
 int
-tls_session_connected_callback (u32 tls_app_index, u32 ho_ctx_index,
-				session_t * tls_session, session_error_t err)
+tls_session_connected_cb (u32 tls_app_index, u32 ho_ctx_index,
+			  session_t *tls_session, session_error_t err)
 {
   session_t *app_session;
   tls_ctx_t *ho_ctx, *ctx;
+  session_type_t st;
   u32 ctx_handle;
 
   ho_ctx = tls_ctx_half_open_get (ho_ctx_index);
@@ -496,7 +540,7 @@ tls_session_connected_callback (u32 tls_app_index, u32 ho_ctx_index,
   ctx->c_flags |= TRANSPORT_CONNECTION_F_NO_LOOKUP;
 
   TLS_DBG (1, "TCP connect for %u returned %u. New connection [%u]%x",
-	   ho_ctx_index, is_fail, vlib_get_thread_index (),
+	   ho_ctx_index, err, vlib_get_thread_index (),
 	   (ctx) ? ctx_handle : ~0);
 
   ctx->tls_session_handle = session_handle (tls_session);
@@ -508,10 +552,43 @@ tls_session_connected_callback (u32 tls_app_index, u32 ho_ctx_index,
   app_session = session_alloc (ctx->c_thread_index);
   app_session->session_state = SESSION_STATE_CREATED;
   ctx->c_s_index = app_session->session_index;
+  st = session_type_from_proto_and_ip (TRANSPORT_PROTO_TLS, ctx->tcp_is_ip4);
+  app_session->session_type = st;
+  app_session->connection_index = ctx->tls_ctx_handle;
+
+  return tls_ctx_init_client (ctx);
+}
+
+int
+dtls_session_connected_cb (u32 app_wrk_index, u32 ctx_handle, session_t *us,
+			   session_error_t err)
+{
+  tls_ctx_t *ctx;
+
+  ctx = tls_ctx_get_w_thread (ctx_handle, 1 /* udp allocs on thread 1 */);
+
+  ctx->tls_session_handle = session_handle (us);
+  ctx->c_flags |= TRANSPORT_CONNECTION_F_NO_LOOKUP;
+  us->opaque = ctx_handle;
+
+  /* We don't preallocate the app session because the udp session might
+   * actually migrate to a different worker at the end of the handshake */
 
   return tls_ctx_init_client (ctx);
 }
 
+int
+tls_session_connected_callback (u32 tls_app_index, u32 ho_ctx_index,
+				session_t *tls_session, session_error_t err)
+{
+  if (session_get_transport_proto (tls_session) == TRANSPORT_PROTO_TCP)
+    return tls_session_connected_cb (tls_app_index, ho_ctx_index, tls_session,
+				     err);
+  else
+    return dtls_session_connected_cb (tls_app_index, ho_ctx_index, tls_session,
+				      err);
+}
+
 static void
 tls_app_session_cleanup (session_t * s, session_cleanup_ntf_t ntf)
 {
@@ -531,7 +608,42 @@ tls_app_session_cleanup (session_t * s, session_cleanup_ntf_t ntf)
   tls_ctx_free (ctx);
 }
 
-/* *INDENT-OFF* */
+static void
+dtls_migrate_udp (void *arg)
+{
+  tls_ctx_t *ctx = (tls_ctx_t *) arg;
+  u32 ctx_handle, thread_index;
+  session_t *us;
+
+  thread_index = session_thread_from_handle (ctx->tls_session_handle);
+  ASSERT (thread_index == vlib_get_thread_index ());
+
+  ctx_handle = tls_ctx_attach (ctx->tls_ctx_engine, thread_index, ctx);
+  ctx = tls_ctx_get_w_thread (ctx_handle, thread_index);
+  ctx->tls_ctx_handle = ctx_handle;
+
+  us = session_get_from_handle (ctx->tls_session_handle);
+  us->opaque = ctx_handle;
+  us->flags &= ~SESSION_F_IS_MIGRATING;
+  if (svm_fifo_max_dequeue (us->tx_fifo))
+    session_send_io_evt_to_thread (us->tx_fifo, SESSION_IO_EVT_TX);
+}
+
+static void
+dtls_session_migrate_callback (session_t *us, session_handle_t new_sh)
+{
+  u32 new_thread = session_thread_from_handle (new_sh);
+  tls_ctx_t *ctx;
+
+  /* Migrate dtls context to new thread */
+  ctx = tls_ctx_get_w_thread (us->opaque, us->thread_index);
+  ctx->tls_session_handle = new_sh;
+  ctx = tls_ctx_detach (ctx);
+  ctx->is_migrated = 1;
+
+  session_send_rpc_evt_to_thread (new_thread, dtls_migrate_udp, (void *) ctx);
+}
+
 static session_cb_vft_t tls_app_cb_vft = {
   .session_accept_callback = tls_session_accept_callback,
   .session_disconnect_callback = tls_session_disconnect_callback,
@@ -541,16 +653,16 @@ static session_cb_vft_t tls_app_cb_vft = {
   .del_segment_callback = tls_del_segment_callback,
   .builtin_app_rx_callback = tls_app_rx_callback,
   .builtin_app_tx_callback = tls_app_tx_callback,
+  .session_migrate_callback = dtls_session_migrate_callback,
   .session_cleanup_callback = tls_app_session_cleanup,
 };
-/* *INDENT-ON* */
 
 int
 tls_connect (transport_endpoint_cfg_t * tep)
 {
   vnet_connect_args_t _cargs = { {}, }, *cargs = &_cargs;
-  session_endpoint_cfg_t *sep;
   crypto_engine_type_t engine_type;
+  session_endpoint_cfg_t *sep;
   tls_main_t *tm = &tls_main;
   app_worker_t *app_wrk;
   application_t *app;
@@ -574,6 +686,7 @@ tls_connect (transport_endpoint_cfg_t * tep)
   ctx->parent_app_api_context = sep->opaque;
   ctx->tcp_is_ip4 = sep->is_ip4;
   ctx->ckpair_index = sep->ckpair_index;
+  ctx->tls_type = sep->transport_proto;
   if (sep->hostname)
     {
       ctx->srv_hostname = format (0, "%v", sep->hostname);
@@ -638,6 +751,11 @@ tls_start_listen (u32 app_listener_index, transport_endpoint_t * tep)
   args->sep_ext = *sep;
   args->sep_ext.ns_index = app->ns_index;
   args->sep_ext.transport_proto = TRANSPORT_PROTO_TCP;
+  if (sep->transport_proto == TRANSPORT_PROTO_DTLS)
+    {
+      args->sep_ext.transport_proto = TRANSPORT_PROTO_UDP;
+      args->sep_ext.transport_flags = TRANSPORT_CFG_F_CONNECTED;
+    }
   if (vnet_listen (args))
     return -1;
 
@@ -656,6 +774,7 @@ tls_start_listen (u32 app_listener_index, transport_endpoint_t * tep)
   lctx->tcp_is_ip4 = sep->is_ip4;
   lctx->tls_ctx_engine = engine_type;
   lctx->ckpair_index = sep->ckpair_index;
+  lctx->tls_type = sep->transport_proto;
 
   if (tls_vfts[engine_type].ctx_start_listen (lctx))
     {
@@ -694,7 +813,7 @@ tls_stop_listen (u32 lctx_index)
   sep.fib_index = lc->fib_index;
   sep.port = lc->lcl_port;
   sep.is_ip4 = lc->is_ip4;
-  sep.transport_proto = TRANSPORT_PROTO_TLS;
+  sep.transport_proto = lctx->tls_type;
   clib_memcpy (&sep.ip, &lc->lcl_ip, sizeof (lc->lcl_ip));
   session_lookup_del_session_endpoint2 (&sep);
 
@@ -749,13 +868,15 @@ format_tls_ctx (u8 * s, va_list * args)
 {
   u32 tcp_si, tcp_ti, ctx_index, ctx_engine;
   tls_ctx_t *ctx = va_arg (*args, tls_ctx_t *);
+  char *proto;
 
+  proto = ctx->tls_type == TRANSPORT_PROTO_TLS ? "TLS" : "DTLS";
   session_parse_handle (ctx->tls_session_handle, &tcp_si, &tcp_ti);
   tls_ctx_parse_handle (ctx->tls_ctx_handle, &ctx_index, &ctx_engine);
-  s = format (s, "[%d:%d][TLS] app_wrk %u index %u engine %u tcp %d:%d",
-	      ctx->c_thread_index, ctx->c_s_index,
-	      ctx->parent_app_wrk_index, ctx_index,
-	      ctx_engine, tcp_ti, tcp_si);
+  s =
+    format (s, "[%d:%d][%s] app_wrk %u index %u engine %u ts %d:%d",
+	    ctx->c_thread_index, ctx->c_s_index, proto,
+	    ctx->parent_app_wrk_index, ctx_index, ctx_engine, tcp_ti, tcp_si);
 
   return s;
 }
@@ -766,13 +887,15 @@ format_tls_listener_ctx (u8 * s, va_list * args)
   session_t *tls_listener;
   app_listener_t *al;
   tls_ctx_t *ctx;
+  char *proto;
 
   ctx = va_arg (*args, tls_ctx_t *);
 
+  proto = ctx->tls_type == TRANSPORT_PROTO_TLS ? "TLS" : "DTLS";
   al = app_listener_get_w_handle (ctx->tls_session_handle);
   tls_listener = app_listener_get_session (al);
-  s = format (s, "[%d:%d][TLS] app_wrk %u engine %u tcp %d:%d",
-	      ctx->c_thread_index, ctx->c_s_index,
+  s = format (s, "[%d:%d][%s] app_wrk %u engine %u ts %d:%d",
+	      ctx->c_thread_index, ctx->c_s_index, proto,
 	      ctx->parent_app_wrk_index, ctx->tls_ctx_engine,
 	      tls_listener->thread_index, tls_listener->session_index);
 
@@ -926,7 +1049,6 @@ tls_enable (vlib_main_t * vm, u8 is_en)
   return 0;
 }
 
-/* *INDENT-OFF* */
 static const transport_proto_vft_t tls_proto = {
   .enable = tls_enable,
   .connect = tls_connect,
@@ -948,7 +1070,89 @@ static const transport_proto_vft_t tls_proto = {
     .service_type = TRANSPORT_SERVICE_APP,
   },
 };
-/* *INDENT-ON* */
+
+int
+dtls_connect (transport_endpoint_cfg_t *tep)
+{
+  vnet_connect_args_t _cargs = { {}, }, *cargs = &_cargs;
+  crypto_engine_type_t engine_type;
+  session_endpoint_cfg_t *sep;
+  tls_main_t *tm = &tls_main;
+  app_worker_t *app_wrk;
+  application_t *app;
+  tls_ctx_t *ctx;
+  u32 ctx_handle;
+  int rv;
+
+  sep = (session_endpoint_cfg_t *) tep;
+  app_wrk = app_worker_get (sep->app_wrk_index);
+  app = application_get (app_wrk->app_index);
+  engine_type = tls_get_engine_type (app->tls_engine);
+  if (engine_type == CRYPTO_ENGINE_NONE)
+    {
+      clib_warning ("No tls engine_type available");
+      return -1;
+    }
+
+  ctx_handle = tls_ctx_alloc_w_thread (engine_type, 1 /* because of udp */);
+  ctx = tls_ctx_get_w_thread (ctx_handle, 1);
+  ctx->parent_app_wrk_index = sep->app_wrk_index;
+  ctx->parent_app_api_context = sep->opaque;
+  ctx->tcp_is_ip4 = sep->is_ip4;
+  ctx->ckpair_index = sep->ckpair_index;
+  ctx->tls_type = sep->transport_proto;
+  ctx->tls_ctx_handle = ctx_handle;
+  if (sep->hostname)
+    {
+      ctx->srv_hostname = format (0, "%v", sep->hostname);
+      vec_terminate_c_string (ctx->srv_hostname);
+    }
+
+  app_worker_alloc_connects_segment_manager (app_wrk);
+  ctx->tls_ctx_engine = engine_type;
+
+  clib_memcpy_fast (&cargs->sep, sep, sizeof (session_endpoint_t));
+  cargs->sep.transport_proto = TRANSPORT_PROTO_UDP;
+  cargs->app_index = tm->app_index;
+  cargs->api_context = ctx_handle;
+  cargs->sep_ext.ns_index = app->ns_index;
+  cargs->sep_ext.transport_flags = TRANSPORT_CFG_F_CONNECTED;
+  if ((rv = vnet_connect (cargs)))
+    return rv;
+
+  TLS_DBG (1, "New DTLS connect request %x engine %d", ctx_handle,
+	   engine_type);
+  return 0;
+}
+
+static void
+dtls_cleanup_callback (u32 ctx_index, u32 thread_index)
+{
+  /* No op */
+}
+
+static const transport_proto_vft_t dtls_proto = {
+  .enable = 0,
+  .connect = dtls_connect,
+  .close = tls_disconnect,
+  .start_listen = tls_start_listen,
+  .stop_listen = tls_stop_listen,
+  .get_connection = tls_connection_get,
+  .get_listener = tls_listener_get,
+  .custom_tx = tls_custom_tx_callback,
+  .cleanup = dtls_cleanup_callback,
+  .format_connection = format_tls_connection,
+  .format_half_open = format_tls_half_open,
+  .format_listener = format_tls_listener,
+  .get_transport_endpoint = tls_transport_endpoint_get,
+  .get_transport_listener_endpoint = tls_transport_listener_endpoint_get,
+  .transport_options = {
+    .name = "dtls",
+    .short_name = "D",
+    .tx_type = TRANSPORT_TX_INTERNAL,
+    .service_type = TRANSPORT_SERVICE_APP,
+  },
+};
 
 void
 tls_register_engine (const tls_engine_vft_t * vft, crypto_engine_type_t type)
@@ -978,6 +1182,11 @@ tls_init (vlib_main_t * vm)
 			       FIB_PROTOCOL_IP4, ~0);
   transport_register_protocol (TRANSPORT_PROTO_TLS, &tls_proto,
 			       FIB_PROTOCOL_IP6, ~0);
+
+  transport_register_protocol (TRANSPORT_PROTO_DTLS, &dtls_proto,
+			       FIB_PROTOCOL_IP4, ~0);
+  transport_register_protocol (TRANSPORT_PROTO_DTLS, &dtls_proto,
+			       FIB_PROTOCOL_IP6, ~0);
   return 0;
 }
 
diff --git a/src/vnet/tls/tls.h b/src/vnet/tls/tls.h
index d950fe82629..2038fdff133 100644
--- a/src/vnet/tls/tls.h
+++ b/src/vnet/tls/tls.h
@@ -21,7 +21,7 @@
 #ifndef SRC_VNET_TLS_TLS_H_
 #define SRC_VNET_TLS_TLS_H_
 
-#define TLS_DEBUG 		0
+#define TLS_DEBUG		0
 #define TLS_DEBUG_LEVEL_CLIENT 	0
 #define TLS_DEBUG_LEVEL_SERVER 	0
 
@@ -49,6 +49,7 @@ typedef struct tls_cxt_id_
   u32 listener_ctx_index;
   u8 tcp_is_ip4;
   u8 tls_engine_id;
+  void *migrate_ctx;
 } tls_ctx_id_t;
 /* *INDENT-ON* */
 
@@ -73,14 +74,17 @@ typedef struct tls_ctx_
   /* Temporary storage for session open opaque. Overwritten once
    * underlying tcp connection is established */
 #define parent_app_api_context c_tls_ctx_id.parent_app_api_ctx
+#define migration_ctx	       c_tls_ctx_id.migrate_ctx
 
   u8 is_passive_close;
   u8 resume;
   u8 app_closed;
   u8 no_app_session;
+  u8 is_migrated;
   u8 *srv_hostname;
   u32 evt_index;
   u32 ckpair_index;
+  transport_proto_t tls_type;
 } tls_ctx_t;
 
 typedef struct tls_main_
@@ -104,7 +108,10 @@ typedef struct tls_main_
 typedef struct tls_engine_vft_
 {
   u32 (*ctx_alloc) (void);
+  u32 (*ctx_alloc_w_thread) (u32 thread_index);
   void (*ctx_free) (tls_ctx_t * ctx);
+  void *(*ctx_detach) (tls_ctx_t *ctx);
+  u32 (*ctx_attach) (u32 thread_index, void *ctx);
   tls_ctx_t *(*ctx_get) (u32 ctx_index);
   tls_ctx_t *(*ctx_get_w_thread) (u32 ctx_index, u8 thread_index);
   int (*ctx_init_client) (tls_ctx_t * ctx);