diff --git a/tests/src/ssl_helpers.c b/tests/src/ssl_helpers.c
index 618b3ec..150f6e8 100644
--- a/tests/src/ssl_helpers.c
+++ b/tests/src/ssl_helpers.c
@@ -21,3 +21,2428 @@
  */
 
 #include <test/ssl_helpers.h>
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+static int rng_seed = 0xBEEF;
+static int rng_get(void *p_rng, unsigned char *output, size_t output_len)
+{
+    (void) p_rng;
+    for (size_t i = 0; i < output_len; i++) {
+        output[i] = rand();
+    }
+
+    return 0;
+}
+#endif
+
+/*
+ * This function can be passed to mbedtls to receive output logs from it. In
+ * this case, it will count the instances of a mbedtls_test_ssl_log_pattern
+ * in the received logged messages.
+ */
+void mbedtls_test_ssl_log_analyzer(void *ctx, int level,
+                                   const char *file, int line,
+                                   const char *str)
+{
+    mbedtls_test_ssl_log_pattern *p = (mbedtls_test_ssl_log_pattern *) ctx;
+
+    (void) level;
+    (void) line;
+    (void) file;
+
+    if (NULL != p &&
+        NULL != p->pattern &&
+        NULL != strstr(str, p->pattern)) {
+        p->counter++;
+    }
+}
+
+void mbedtls_test_init_handshake_options(
+    mbedtls_test_handshake_test_options *opts)
+{
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+    srand(rng_seed);
+    rng_seed += 0xD0;
+#endif
+    opts->cipher = "";
+    opts->client_min_version = MBEDTLS_SSL_VERSION_UNKNOWN;
+    opts->client_max_version = MBEDTLS_SSL_VERSION_UNKNOWN;
+    opts->server_min_version = MBEDTLS_SSL_VERSION_UNKNOWN;
+    opts->server_max_version = MBEDTLS_SSL_VERSION_UNKNOWN;
+    opts->expected_negotiated_version = MBEDTLS_SSL_VERSION_TLS1_2;
+    opts->expected_handshake_result = 0;
+    opts->expected_ciphersuite = 0;
+    opts->pk_alg = MBEDTLS_PK_RSA;
+    opts->opaque_alg = 0;
+    opts->opaque_alg2 = 0;
+    opts->opaque_usage = 0;
+    opts->psk_str = NULL;
+    opts->dtls = 0;
+    opts->srv_auth_mode = MBEDTLS_SSL_VERIFY_NONE;
+    opts->serialize = 0;
+    opts->mfl = MBEDTLS_SSL_MAX_FRAG_LEN_NONE;
+    opts->cli_msg_len = 100;
+    opts->srv_msg_len = 100;
+    opts->expected_cli_fragments = 1;
+    opts->expected_srv_fragments = 1;
+    opts->renegotiate = 0;
+    opts->legacy_renegotiation = MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION;
+    opts->srv_log_obj = NULL;
+    opts->srv_log_obj = NULL;
+    opts->srv_log_fun = NULL;
+    opts->cli_log_fun = NULL;
+    opts->resize_buffers = 1;
+#if defined(MBEDTLS_SSL_CACHE_C)
+    opts->cache = NULL;
+    ASSERT_ALLOC(opts->cache, 1);
+    mbedtls_ssl_cache_init(opts->cache);
+exit:
+    return;
+#endif
+}
+
+void mbedtls_test_free_handshake_options(
+    mbedtls_test_handshake_test_options *opts)
+{
+#if defined(MBEDTLS_SSL_CACHE_C)
+    mbedtls_ssl_cache_free(opts->cache);
+    mbedtls_free(opts->cache);
+#else
+    (void) opts;
+#endif
+}
+
+#if defined(MBEDTLS_TEST_HOOKS)
+static void set_chk_buf_ptr_args(
+    mbedtls_ssl_chk_buf_ptr_args *args,
+    unsigned char *cur, unsigned char *end, size_t need)
+{
+    args->cur = cur;
+    args->end = end;
+    args->need = need;
+}
+
+static void reset_chk_buf_ptr_args(mbedtls_ssl_chk_buf_ptr_args *args)
+{
+    memset(args, 0, sizeof(*args));
+}
+#endif /* MBEDTLS_TEST_HOOKS */
+
+/*
+ * Buffer structure for custom I/O callbacks.
+ */
+
+/*
+ * Initialises \p buf. After calling this function it is safe to call
+ * `mbedtls_test_ssl_buffer_free()` on \p buf.
+ */
+void mbedtls_test_ssl_buffer_init(mbedtls_test_ssl_buffer *buf)
+{
+    memset(buf, 0, sizeof(*buf));
+}
+
+/*
+ * Sets up \p buf. After calling this function it is safe to call
+ * `mbedtls_test_ssl_buffer_put()` and `mbedtls_test_ssl_buffer_get()`
+ * on \p buf.
+ */
+int mbedtls_test_ssl_buffer_setup(mbedtls_test_ssl_buffer *buf,
+                                  size_t capacity)
+{
+    buf->buffer = (unsigned char *) mbedtls_calloc(capacity,
+                                                   sizeof(unsigned char));
+    if (NULL == buf->buffer) {
+        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
+    }
+    buf->capacity = capacity;
+
+    return 0;
+}
+
+void mbedtls_test_ssl_buffer_free(mbedtls_test_ssl_buffer *buf)
+{
+    if (buf->buffer != NULL) {
+        mbedtls_free(buf->buffer);
+    }
+
+    memset(buf, 0, sizeof(*buf));
+}
+
+/*
+ * Puts \p input_len bytes from the \p input buffer into the ring buffer \p buf.
+ *
+ * \p buf must have been initialized and set up by calling
+ * `mbedtls_test_ssl_buffer_init()` and `mbedtls_test_ssl_buffer_setup()`.
+ *
+ * \retval  \p input_len, if the data fits.
+ * \retval  0 <= value < \p input_len, if the data does not fit.
+ * \retval  -1, if \p buf is NULL, it hasn't been set up or \p input_len is not
+ *          zero and \p input is NULL.
+ */
+int mbedtls_test_ssl_buffer_put(mbedtls_test_ssl_buffer *buf,
+                                const unsigned char *input, size_t input_len)
+{
+    size_t overflow = 0;
+
+    if ((buf == NULL) || (buf->buffer == NULL)) {
+        return -1;
+    }
+
+    /* Reduce input_len to a number that fits in the buffer. */
+    if ((buf->content_length + input_len) > buf->capacity) {
+        input_len = buf->capacity - buf->content_length;
+    }
+
+    if (input == NULL) {
+        return (input_len == 0) ? 0 : -1;
+    }
+
+    /* Check if the buffer has not come full circle and free space is not in
+     * the middle */
+    if (buf->start + buf->content_length < buf->capacity) {
+
+        /* Calculate the number of bytes that need to be placed at lower memory
+         * address */
+        if (buf->start + buf->content_length + input_len
+            > buf->capacity) {
+            overflow = (buf->start + buf->content_length + input_len)
+                       % buf->capacity;
+        }
+
+        memcpy(buf->buffer + buf->start + buf->content_length, input,
+               input_len - overflow);
+        memcpy(buf->buffer, input + input_len - overflow, overflow);
+
+    } else {
+        /* The buffer has come full circle and free space is in the middle */
+        memcpy(buf->buffer + buf->start + buf->content_length - buf->capacity,
+               input, input_len);
+    }
+
+    buf->content_length += input_len;
+    return input_len;
+}
+
+/*
+ * Gets \p output_len bytes from the ring buffer \p buf into the
+ * \p output buffer. The output buffer can be NULL, in this case a part of the
+ * ring buffer will be dropped, if the requested length is available.
+ *
+ * \p buf must have been initialized and set up by calling
+ * `mbedtls_test_ssl_buffer_init()` and `mbedtls_test_ssl_buffer_setup()`.
+ *
+ * \retval  \p output_len, if the data is available.
+ * \retval  0 <= value < \p output_len, if the data is not available.
+ * \retval  -1, if \buf is NULL or it hasn't been set up.
+ */
+int mbedtls_test_ssl_buffer_get(mbedtls_test_ssl_buffer *buf,
+                                unsigned char *output, size_t output_len)
+{
+    size_t overflow = 0;
+
+    if ((buf == NULL) || (buf->buffer == NULL)) {
+        return -1;
+    }
+
+    if (output == NULL && output_len == 0) {
+        return 0;
+    }
+
+    if (buf->content_length < output_len) {
+        output_len = buf->content_length;
+    }
+
+    /* Calculate the number of bytes that need to be drawn from lower memory
+     * address */
+    if (buf->start + output_len > buf->capacity) {
+        overflow = (buf->start + output_len) % buf->capacity;
+    }
+
+    if (output != NULL) {
+        memcpy(output, buf->buffer + buf->start, output_len - overflow);
+        memcpy(output + output_len - overflow, buf->buffer, overflow);
+    }
+
+    buf->content_length -= output_len;
+    buf->start = (buf->start + output_len) % buf->capacity;
+
+    return output_len;
+}
+
+/*
+ * Errors used in the message transport mock tests
+ */
+ #define MBEDTLS_TEST_ERROR_ARG_NULL -11
+ #define MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED -44
+
+/*
+ * Setup and free functions for the message metadata queue.
+ *
+ * \p capacity describes the number of message metadata chunks that can be held
+ *    within the queue.
+ *
+ * \retval  0, if a metadata queue of a given length can be allocated.
+ * \retval  MBEDTLS_ERR_SSL_ALLOC_FAILED, if allocation failed.
+ */
+int mbedtls_test_ssl_message_queue_setup(mbedtls_test_ssl_message_queue *queue,
+                                         size_t capacity)
+{
+    queue->messages = (size_t *) mbedtls_calloc(capacity, sizeof(size_t));
+    if (NULL == queue->messages) {
+        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
+    }
+
+    queue->capacity = capacity;
+    queue->pos = 0;
+    queue->num = 0;
+
+    return 0;
+}
+
+void mbedtls_test_ssl_message_queue_free(mbedtls_test_ssl_message_queue *queue)
+{
+    if (queue == NULL) {
+        return;
+    }
+
+    if (queue->messages != NULL) {
+        mbedtls_free(queue->messages);
+    }
+
+    memset(queue, 0, sizeof(*queue));
+}
+
+/*
+ * Push message length information onto the message metadata queue.
+ * This will become the last element to leave it (fifo).
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_ERR_SSL_WANT_WRITE, if the queue is full.
+ * \retval  \p len, if the push was successful.
+ */
+int mbedtls_test_ssl_message_queue_push_info(
+    mbedtls_test_ssl_message_queue *queue, size_t len)
+{
+    int place;
+    if (queue == NULL) {
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+    }
+
+    if (queue->num >= queue->capacity) {
+        return MBEDTLS_ERR_SSL_WANT_WRITE;
+    }
+
+    place = (queue->pos + queue->num) % queue->capacity;
+    queue->messages[place] = len;
+    queue->num++;
+    return len;
+}
+
+/*
+ * Pop information about the next message length from the queue. This will be
+ * the oldest inserted message length(fifo). \p msg_len can be null, in which
+ * case the data will be popped from the queue but not copied anywhere.
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_ERR_SSL_WANT_READ, if the queue is empty.
+ * \retval  message length, if the pop was successful, up to the given
+            \p buf_len.
+ */
+int mbedtls_test_ssl_message_queue_pop_info(
+    mbedtls_test_ssl_message_queue *queue, size_t buf_len)
+{
+    size_t message_length;
+    if (queue == NULL) {
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+    }
+    if (queue->num == 0) {
+        return MBEDTLS_ERR_SSL_WANT_READ;
+    }
+
+    message_length = queue->messages[queue->pos];
+    queue->messages[queue->pos] = 0;
+    queue->num--;
+    queue->pos++;
+    queue->pos %= queue->capacity;
+    if (queue->pos < 0) {
+        queue->pos += queue->capacity;
+    }
+
+    return (message_length > buf_len) ? buf_len : message_length;
+}
+
+/*
+ * Take a peek on the info about the next message length from the queue.
+ * This will be the oldest inserted message length(fifo).
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_ERR_SSL_WANT_READ, if the queue is empty.
+ * \retval  0, if the peek was successful.
+ * \retval  MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED, if the given buffer length is
+ *          too small to fit the message. In this case the \p msg_len will be
+ *          set to the full message length so that the
+ *          caller knows what portion of the message can be dropped.
+ */
+int mbedtls_test_message_queue_peek_info(mbedtls_test_ssl_message_queue *queue,
+                                         size_t buf_len, size_t *msg_len)
+{
+    if (queue == NULL || msg_len == NULL) {
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+    }
+    if (queue->num == 0) {
+        return MBEDTLS_ERR_SSL_WANT_READ;
+    }
+
+    *msg_len = queue->messages[queue->pos];
+    return (*msg_len > buf_len) ? MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED : 0;
+}
+
+/*
+ * Setup and teardown functions for mock sockets.
+ */
+void mbedtls_mock_socket_init(mbedtls_test_mock_socket *socket)
+{
+    memset(socket, 0, sizeof(*socket));
+}
+
+/*
+ * Closes the socket \p socket.
+ *
+ * \p socket must have been previously initialized by calling
+ * mbedtls_mock_socket_init().
+ *
+ * This function frees all allocated resources and both sockets are aware of the
+ * new connection state.
+ *
+ * That is, this function does not simulate half-open TCP connections and the
+ * phenomenon that when closing a UDP connection the peer is not aware of the
+ * connection having been closed.
+ */
+void mbedtls_test_mock_socket_close(mbedtls_test_mock_socket *socket)
+{
+    if (socket == NULL) {
+        return;
+    }
+
+    if (socket->input != NULL) {
+        mbedtls_test_ssl_buffer_free(socket->input);
+        mbedtls_free(socket->input);
+    }
+
+    if (socket->output != NULL) {
+        mbedtls_test_ssl_buffer_free(socket->output);
+        mbedtls_free(socket->output);
+    }
+
+    if (socket->peer != NULL) {
+        memset(socket->peer, 0, sizeof(*socket->peer));
+    }
+
+    memset(socket, 0, sizeof(*socket));
+}
+
+/*
+ * Establishes a connection between \p peer1 and \p peer2.
+ *
+ * \p peer1 and \p peer2 must have been previously initialized by calling
+ * mbedtls_mock_socket_init().
+ *
+ * The capacities of the internal buffers are set to \p bufsize. Setting this to
+ * the correct value allows for simulation of MTU, sanity testing the mock
+ * implementation and mocking TCP connections with lower memory cost.
+ */
+int mbedtls_test_mock_socket_connect(mbedtls_test_mock_socket *peer1,
+                                     mbedtls_test_mock_socket *peer2,
+                                     size_t bufsize)
+{
+    int ret = -1;
+
+    peer1->output =
+        (mbedtls_test_ssl_buffer *) mbedtls_calloc(
+            1, sizeof(mbedtls_test_ssl_buffer));
+    if (peer1->output == NULL) {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+    mbedtls_test_ssl_buffer_init(peer1->output);
+    if (0 != (ret = mbedtls_test_ssl_buffer_setup(peer1->output, bufsize))) {
+        goto exit;
+    }
+
+    peer2->output =
+        (mbedtls_test_ssl_buffer *) mbedtls_calloc(
+            1, sizeof(mbedtls_test_ssl_buffer));
+    if (peer2->output == NULL) {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+    mbedtls_test_ssl_buffer_init(peer2->output);
+    if (0 != (ret = mbedtls_test_ssl_buffer_setup(peer2->output, bufsize))) {
+        goto exit;
+    }
+
+    peer1->peer = peer2;
+    peer2->peer = peer1;
+    peer1->input = peer2->output;
+    peer2->input = peer1->output;
+
+    peer1->status = peer2->status = MBEDTLS_MOCK_SOCKET_CONNECTED;
+    ret = 0;
+
+exit:
+
+    if (ret != 0) {
+        mbedtls_test_mock_socket_close(peer1);
+        mbedtls_test_mock_socket_close(peer2);
+    }
+
+    return ret;
+}
+
+/*
+ * Callbacks for simulating blocking I/O over connection-oriented transport.
+ */
+
+int mbedtls_test_mock_tcp_send_b(void *ctx, const unsigned char *buf,
+                                 size_t len)
+{
+    mbedtls_test_mock_socket *socket = (mbedtls_test_mock_socket *) ctx;
+
+    if (socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED) {
+        return -1;
+    }
+
+    return mbedtls_test_ssl_buffer_put(socket->output, buf, len);
+}
+
+int mbedtls_test_mock_tcp_recv_b(void *ctx, unsigned char *buf, size_t len)
+{
+    mbedtls_test_mock_socket *socket = (mbedtls_test_mock_socket *) ctx;
+
+    if (socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED) {
+        return -1;
+    }
+
+    return mbedtls_test_ssl_buffer_get(socket->input, buf, len);
+}
+
+/*
+ * Callbacks for simulating non-blocking I/O over connection-oriented transport.
+ */
+
+int mbedtls_test_mock_tcp_send_nb(void *ctx, const unsigned char *buf,
+                                  size_t len)
+{
+    mbedtls_test_mock_socket *socket = (mbedtls_test_mock_socket *) ctx;
+
+    if (socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED) {
+        return -1;
+    }
+
+    if (socket->output->capacity == socket->output->content_length) {
+        return MBEDTLS_ERR_SSL_WANT_WRITE;
+    }
+
+    return mbedtls_test_ssl_buffer_put(socket->output, buf, len);
+}
+
+int mbedtls_test_mock_tcp_recv_nb(void *ctx, unsigned char *buf, size_t len)
+{
+    mbedtls_test_mock_socket *socket = (mbedtls_test_mock_socket *) ctx;
+
+    if (socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED) {
+        return -1;
+    }
+
+    if (socket->input->content_length == 0) {
+        return MBEDTLS_ERR_SSL_WANT_READ;
+    }
+
+    return mbedtls_test_ssl_buffer_get(socket->input, buf, len);
+}
+
+void mbedtls_test_message_socket_init(mbedtls_test_message_socket_context *ctx)
+{
+    ctx->queue_input = NULL;
+    ctx->queue_output = NULL;
+    ctx->socket = NULL;
+}
+
+/*
+ * Setup a given message socket context including initialization of
+ * input/output queues to a chosen capacity of messages. Also set the
+ * corresponding mock socket.
+ *
+ * \retval  0, if everything succeeds.
+ * \retval  MBEDTLS_ERR_SSL_ALLOC_FAILED, if allocation of a message
+ *          queue failed.
+ */
+int mbedtls_test_message_socket_setup(
+    mbedtls_test_ssl_message_queue *queue_input,
+    mbedtls_test_ssl_message_queue *queue_output,
+    size_t queue_capacity,
+    mbedtls_test_mock_socket *socket,
+    mbedtls_test_message_socket_context *ctx)
+{
+    int ret = mbedtls_test_ssl_message_queue_setup(queue_input, queue_capacity);
+    if (ret != 0) {
+        return ret;
+    }
+    ctx->queue_input = queue_input;
+    ctx->queue_output = queue_output;
+    ctx->socket = socket;
+    mbedtls_mock_socket_init(socket);
+
+    return 0;
+}
+
+/*
+ * Close a given message socket context, along with the socket itself. Free the
+ * memory allocated by the input queue.
+ */
+void mbedtls_test_message_socket_close(mbedtls_test_message_socket_context *ctx)
+{
+    if (ctx == NULL) {
+        return;
+    }
+
+    mbedtls_test_ssl_message_queue_free(ctx->queue_input);
+    mbedtls_test_mock_socket_close(ctx->socket);
+    memset(ctx, 0, sizeof(*ctx));
+}
+
+/*
+ * Send one message through a given message socket context.
+ *
+ * \retval  \p len, if everything succeeds.
+ * \retval  MBEDTLS_TEST_ERROR_CONTEXT_ERROR, if any of the needed context
+ *          elements or the context itself is null.
+ * \retval  MBEDTLS_TEST_ERROR_SEND_FAILED if
+ *          mbedtls_test_mock_tcp_send_b failed.
+ * \retval  MBEDTLS_ERR_SSL_WANT_WRITE, if the output queue is full.
+ *
+ * This function will also return any error from
+ * mbedtls_test_ssl_message_queue_push_info.
+ */
+int mbedtls_test_mock_tcp_send_msg(void *ctx, const unsigned char *buf,
+                                   size_t len)
+{
+    mbedtls_test_ssl_message_queue *queue;
+    mbedtls_test_mock_socket *socket;
+    mbedtls_test_message_socket_context *context =
+        (mbedtls_test_message_socket_context *) ctx;
+
+    if (context == NULL || context->socket == NULL
+        || context->queue_output == NULL) {
+        return MBEDTLS_TEST_ERROR_CONTEXT_ERROR;
+    }
+
+    queue = context->queue_output;
+    socket = context->socket;
+
+    if (queue->num >= queue->capacity) {
+        return MBEDTLS_ERR_SSL_WANT_WRITE;
+    }
+
+    if (mbedtls_test_mock_tcp_send_b(socket, buf, len) != (int) len) {
+        return MBEDTLS_TEST_ERROR_SEND_FAILED;
+    }
+
+    return mbedtls_test_ssl_message_queue_push_info(queue, len);
+}
+
+/*
+ * Receive one message from a given message socket context and return message
+ * length or an error.
+ *
+ * \retval  message length, if everything succeeds.
+ * \retval  MBEDTLS_TEST_ERROR_CONTEXT_ERROR, if any of the needed context
+ *          elements or the context itself is null.
+ * \retval  MBEDTLS_TEST_ERROR_RECV_FAILED if
+ *          mbedtls_test_mock_tcp_recv_b failed.
+ *
+ * This function will also return any error other than
+ * MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED from
+ * mbedtls_test_message_queue_peek_info.
+ */
+int mbedtls_test_mock_tcp_recv_msg(void *ctx, unsigned char *buf,
+                                   size_t buf_len)
+{
+    mbedtls_test_ssl_message_queue *queue;
+    mbedtls_test_mock_socket *socket;
+    mbedtls_test_message_socket_context *context =
+        (mbedtls_test_message_socket_context *) ctx;
+    size_t drop_len = 0;
+    size_t msg_len;
+    int ret;
+
+    if (context == NULL || context->socket == NULL
+        || context->queue_input == NULL) {
+        return MBEDTLS_TEST_ERROR_CONTEXT_ERROR;
+    }
+
+    queue = context->queue_input;
+    socket = context->socket;
+
+    /* Peek first, so that in case of a socket error the data remains in
+     * the queue. */
+    ret = mbedtls_test_message_queue_peek_info(queue, buf_len, &msg_len);
+    if (ret == MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED) {
+        /* Calculate how much to drop */
+        drop_len = msg_len - buf_len;
+
+        /* Set the requested message len to be buffer length */
+        msg_len = buf_len;
+    } else if (ret != 0) {
+        return ret;
+    }
+
+    if (mbedtls_test_mock_tcp_recv_b(socket, buf, msg_len) != (int) msg_len) {
+        return MBEDTLS_TEST_ERROR_RECV_FAILED;
+    }
+
+    if (ret == MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED) {
+        /* Drop the remaining part of the message */
+        if (mbedtls_test_mock_tcp_recv_b(socket, NULL, drop_len)
+            != (int) drop_len) {
+            /* Inconsistent state - part of the message was read,
+             * and a part couldn't. Not much we can do here, but it should not
+             * happen in test environment, unless forced manually. */
+        }
+    }
+    mbedtls_test_ssl_message_queue_pop_info(queue, buf_len);
+
+    return msg_len;
+}
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+
+/*
+ * Deinitializes certificates from endpoint represented by \p ep.
+ */
+void mbedtls_endpoint_certificate_free(mbedtls_test_ssl_endpoint *ep)
+{
+    mbedtls_test_ssl_endpoint_certificate *cert = &(ep->cert);
+    if (cert != NULL) {
+        if (cert->ca_cert != NULL) {
+            mbedtls_x509_crt_free(cert->ca_cert);
+            mbedtls_free(cert->ca_cert);
+            cert->ca_cert = NULL;
+        }
+        if (cert->cert != NULL) {
+            mbedtls_x509_crt_free(cert->cert);
+            mbedtls_free(cert->cert);
+            cert->cert = NULL;
+        }
+        if (cert->pkey != NULL) {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            if (mbedtls_pk_get_type(cert->pkey) == MBEDTLS_PK_OPAQUE) {
+                mbedtls_svc_key_id_t *key_slot = cert->pkey->pk_ctx;
+                psa_destroy_key(*key_slot);
+            }
+#endif
+            mbedtls_pk_free(cert->pkey);
+            mbedtls_free(cert->pkey);
+            cert->pkey = NULL;
+        }
+    }
+}
+
+/*
+ * Initializes \p ep_cert structure and assigns it to endpoint
+ * represented by \p ep.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_test_ssl_endpoint_certificate_init(mbedtls_test_ssl_endpoint *ep,
+                                               int pk_alg,
+                                               int opaque_alg, int opaque_alg2,
+                                               int opaque_usage)
+{
+    int i = 0;
+    int ret = -1;
+    mbedtls_test_ssl_endpoint_certificate *cert = NULL;
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    mbedtls_svc_key_id_t key_slot = MBEDTLS_SVC_KEY_ID_INIT;
+#endif
+
+    if (ep == NULL) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    cert = &(ep->cert);
+    ASSERT_ALLOC(cert->ca_cert, 1);
+    ASSERT_ALLOC(cert->cert, 1);
+    ASSERT_ALLOC(cert->pkey, 1);
+
+    mbedtls_x509_crt_init(cert->ca_cert);
+    mbedtls_x509_crt_init(cert->cert);
+    mbedtls_pk_init(cert->pkey);
+
+    /* Load the trusted CA */
+
+    for (i = 0; mbedtls_test_cas_der[i] != NULL; i++) {
+        ret = mbedtls_x509_crt_parse_der(
+            cert->ca_cert,
+            (const unsigned char *) mbedtls_test_cas_der[i],
+            mbedtls_test_cas_der_len[i]);
+        TEST_ASSERT(ret == 0);
+    }
+
+    /* Load own certificate and private key */
+
+    if (ep->conf.endpoint == MBEDTLS_SSL_IS_SERVER) {
+        if (pk_alg == MBEDTLS_PK_RSA) {
+            ret = mbedtls_x509_crt_parse(
+                cert->cert,
+                (const unsigned char *) mbedtls_test_srv_crt_rsa_sha256_der,
+                mbedtls_test_srv_crt_rsa_sha256_der_len);
+            TEST_ASSERT(ret == 0);
+
+            ret = mbedtls_pk_parse_key(
+                cert->pkey,
+                (const unsigned char *) mbedtls_test_srv_key_rsa_der,
+                mbedtls_test_srv_key_rsa_der_len, NULL, 0,
+                mbedtls_test_rnd_std_rand, NULL);
+            TEST_ASSERT(ret == 0);
+        } else {
+            ret = mbedtls_x509_crt_parse(
+                cert->cert,
+                (const unsigned char *) mbedtls_test_srv_crt_ec_der,
+                mbedtls_test_srv_crt_ec_der_len);
+            TEST_ASSERT(ret == 0);
+
+            ret = mbedtls_pk_parse_key(
+                cert->pkey,
+                (const unsigned char *) mbedtls_test_srv_key_ec_der,
+                mbedtls_test_srv_key_ec_der_len, NULL, 0,
+                mbedtls_test_rnd_std_rand, NULL);
+            TEST_ASSERT(ret == 0);
+        }
+    } else {
+        if (pk_alg == MBEDTLS_PK_RSA) {
+            ret = mbedtls_x509_crt_parse(
+                cert->cert,
+                (const unsigned char *) mbedtls_test_cli_crt_rsa_der,
+                mbedtls_test_cli_crt_rsa_der_len);
+            TEST_ASSERT(ret == 0);
+
+            ret = mbedtls_pk_parse_key(
+                cert->pkey,
+                (const unsigned char *) mbedtls_test_cli_key_rsa_der,
+                mbedtls_test_cli_key_rsa_der_len, NULL, 0,
+                mbedtls_test_rnd_std_rand, NULL);
+            TEST_ASSERT(ret == 0);
+        } else {
+            ret = mbedtls_x509_crt_parse(
+                cert->cert,
+                (const unsigned char *) mbedtls_test_cli_crt_ec_der,
+                mbedtls_test_cli_crt_ec_len);
+            TEST_ASSERT(ret == 0);
+
+            ret = mbedtls_pk_parse_key(
+                cert->pkey,
+                (const unsigned char *) mbedtls_test_cli_key_ec_der,
+                mbedtls_test_cli_key_ec_der_len, NULL, 0,
+                mbedtls_test_rnd_std_rand, NULL);
+            TEST_ASSERT(ret == 0);
+        }
+    }
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    if (opaque_alg != 0) {
+        TEST_EQUAL(mbedtls_pk_wrap_as_opaque(cert->pkey, &key_slot,
+                                             opaque_alg, opaque_usage,
+                                             opaque_alg2), 0);
+    }
+#else
+    (void) opaque_alg;
+    (void) opaque_alg2;
+    (void) opaque_usage;
+#endif
+
+    mbedtls_ssl_conf_ca_chain(&(ep->conf), cert->ca_cert, NULL);
+
+    ret = mbedtls_ssl_conf_own_cert(&(ep->conf), cert->cert,
+                                    cert->pkey);
+    TEST_ASSERT(ret == 0);
+    TEST_ASSERT(ep->conf.key_cert != NULL);
+
+    ret = mbedtls_ssl_conf_own_cert(&(ep->conf), NULL, NULL);
+    TEST_ASSERT(ret == 0);
+    TEST_ASSERT(ep->conf.key_cert == NULL);
+
+    ret = mbedtls_ssl_conf_own_cert(&(ep->conf), cert->cert,
+                                    cert->pkey);
+    TEST_ASSERT(ret == 0);
+
+exit:
+    if (ret != 0) {
+        mbedtls_endpoint_certificate_free(ep);
+    }
+
+    return ret;
+}
+
+/*
+ * Initializes \p ep structure. It is important to call
+ * `mbedtls_test_ssl_endpoint_free()` after calling this function
+ * even if it fails.
+ *
+ * \p endpoint_type must be set as MBEDTLS_SSL_IS_SERVER or
+ * MBEDTLS_SSL_IS_CLIENT.
+ * \p pk_alg the algorithm to use, currently only MBEDTLS_PK_RSA and
+ * MBEDTLS_PK_ECDSA are supported.
+ * \p dtls_context - in case of DTLS - this is the context handling metadata.
+ * \p input_queue - used only in case of DTLS.
+ * \p output_queue - used only in case of DTLS.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_test_ssl_endpoint_init(
+    mbedtls_test_ssl_endpoint *ep, int endpoint_type,
+    mbedtls_test_handshake_test_options *options,
+    mbedtls_test_message_socket_context *dtls_context,
+    mbedtls_test_ssl_message_queue *input_queue,
+    mbedtls_test_ssl_message_queue *output_queue,
+    uint16_t *group_list)
+{
+    int ret = -1;
+    uintptr_t user_data_n;
+
+    if (dtls_context != NULL &&
+        (input_queue == NULL || output_queue == NULL)) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+
+    }
+
+    if (ep == NULL) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    memset(ep, 0, sizeof(*ep));
+
+    ep->name = (endpoint_type == MBEDTLS_SSL_IS_SERVER) ? "Server" : "Client";
+
+    mbedtls_ssl_init(&(ep->ssl));
+    mbedtls_ssl_config_init(&(ep->conf));
+    mbedtls_ssl_conf_rng(&(ep->conf), rng_get, NULL);
+
+    TEST_ASSERT(mbedtls_ssl_conf_get_user_data_p(&ep->conf) == NULL);
+    TEST_EQUAL(mbedtls_ssl_conf_get_user_data_n(&ep->conf), 0);
+    TEST_ASSERT(mbedtls_ssl_get_user_data_p(&ep->ssl) == NULL);
+    TEST_EQUAL(mbedtls_ssl_get_user_data_n(&ep->ssl), 0);
+
+    (void) mbedtls_test_rnd_std_rand(NULL,
+                                     (void *) &user_data_n,
+                                     sizeof(user_data_n));
+    mbedtls_ssl_conf_set_user_data_n(&ep->conf, user_data_n);
+    mbedtls_ssl_set_user_data_n(&ep->ssl, user_data_n);
+
+    if (dtls_context != NULL) {
+        TEST_ASSERT(mbedtls_test_message_socket_setup(input_queue, output_queue,
+                                                      100, &(ep->socket),
+                                                      dtls_context) == 0);
+    } else {
+        mbedtls_mock_socket_init(&(ep->socket));
+    }
+
+    /* Non-blocking callbacks without timeout */
+    if (dtls_context != NULL) {
+        mbedtls_ssl_set_bio(&(ep->ssl), dtls_context,
+                            mbedtls_test_mock_tcp_send_msg,
+                            mbedtls_test_mock_tcp_recv_msg,
+                            NULL);
+    } else {
+        mbedtls_ssl_set_bio(&(ep->ssl), &(ep->socket),
+                            mbedtls_test_mock_tcp_send_nb,
+                            mbedtls_test_mock_tcp_recv_nb,
+                            NULL);
+    }
+
+    ret = mbedtls_ssl_config_defaults(&(ep->conf), endpoint_type,
+                                      (dtls_context != NULL) ?
+                                      MBEDTLS_SSL_TRANSPORT_DATAGRAM :
+                                      MBEDTLS_SSL_TRANSPORT_STREAM,
+                                      MBEDTLS_SSL_PRESET_DEFAULT);
+    TEST_ASSERT(ret == 0);
+
+    if (group_list != NULL) {
+        mbedtls_ssl_conf_groups(&(ep->conf), group_list);
+    }
+
+    mbedtls_ssl_conf_authmode(&(ep->conf), MBEDTLS_SSL_VERIFY_REQUIRED);
+
+#if defined(MBEDTLS_SSL_CACHE_C) && defined(MBEDTLS_SSL_SRV_C)
+    if (endpoint_type == MBEDTLS_SSL_IS_SERVER && options->cache != NULL) {
+        mbedtls_ssl_conf_session_cache(&(ep->conf), options->cache,
+                                       mbedtls_ssl_cache_get,
+                                       mbedtls_ssl_cache_set);
+    }
+#endif
+
+    ret = mbedtls_ssl_setup(&(ep->ssl), &(ep->conf));
+    TEST_ASSERT(ret == 0);
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS) && defined(MBEDTLS_SSL_SRV_C)
+    if (endpoint_type == MBEDTLS_SSL_IS_SERVER && dtls_context != NULL) {
+        mbedtls_ssl_conf_dtls_cookies(&(ep->conf), NULL, NULL, NULL);
+    }
+#endif
+
+    ret = mbedtls_test_ssl_endpoint_certificate_init(ep, options->pk_alg,
+                                                     options->opaque_alg,
+                                                     options->opaque_alg2,
+                                                     options->opaque_usage);
+    TEST_ASSERT(ret == 0);
+
+    TEST_EQUAL(mbedtls_ssl_conf_get_user_data_n(&ep->conf), user_data_n);
+    mbedtls_ssl_conf_set_user_data_p(&ep->conf, ep);
+    TEST_EQUAL(mbedtls_ssl_get_user_data_n(&ep->ssl), user_data_n);
+    mbedtls_ssl_set_user_data_p(&ep->ssl, ep);
+
+exit:
+    return ret;
+}
+
+/*
+ * Deinitializes endpoint represented by \p ep.
+ */
+void mbedtls_test_ssl_endpoint_free(
+    mbedtls_test_ssl_endpoint *ep,
+    mbedtls_test_message_socket_context *context)
+{
+    mbedtls_endpoint_certificate_free(ep);
+
+    mbedtls_ssl_free(&(ep->ssl));
+    mbedtls_ssl_config_free(&(ep->conf));
+
+    if (context != NULL) {
+        mbedtls_test_message_socket_close(context);
+    } else {
+        mbedtls_test_mock_socket_close(&(ep->socket));
+    }
+}
+
+/*
+ * This function moves ssl handshake from \p ssl to prescribed \p state.
+ * /p second_ssl is used as second endpoint and their sockets have to be
+ * connected before calling this function.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_test_move_handshake_to_state(mbedtls_ssl_context *ssl,
+                                         mbedtls_ssl_context *second_ssl,
+                                         int state)
+{
+    enum { BUFFSIZE = 1024 };
+    int max_steps = 1000;
+    int ret = 0;
+
+    if (ssl == NULL || second_ssl == NULL) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    /* Perform communication via connected sockets */
+    while ((ssl->state != state) && (--max_steps >= 0)) {
+        /* If /p second_ssl ends the handshake procedure before /p ssl then
+         * there is no need to call the next step */
+        if (!mbedtls_ssl_is_handshake_over(second_ssl)) {
+            ret = mbedtls_ssl_handshake_step(second_ssl);
+            if (ret != 0 && ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
+                return ret;
+            }
+        }
+
+        /* We only care about the \p ssl state and returns, so we call it last,
+         * to leave the iteration as soon as the state is as expected. */
+        ret = mbedtls_ssl_handshake_step(ssl);
+        if (ret != 0 && ret != MBEDTLS_ERR_SSL_WANT_READ &&
+            ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
+            return ret;
+        }
+    }
+
+    return (max_steps >= 0) ? ret : -1;
+}
+
+#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
+
+/*
+ * Write application data. Increase write counter if necessary.
+ */
+int mbedtls_ssl_write_fragment(mbedtls_ssl_context *ssl, unsigned char *buf,
+                               int buf_len, int *written,
+                               const int expected_fragments)
+{
+    /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
+     * a valid no-op for TLS connections. */
+    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
+        TEST_ASSERT(mbedtls_ssl_write(ssl, NULL, 0) == 0);
+    }
+
+    int ret = mbedtls_ssl_write(ssl, buf + *written, buf_len - *written);
+    if (ret > 0) {
+        *written += ret;
+    }
+
+    if (expected_fragments == 0) {
+        /* Used for DTLS and the message size larger than MFL. In that case
+         * the message can not be fragmented and the library should return
+         * MBEDTLS_ERR_SSL_BAD_INPUT_DATA error. This error must be returned
+         * to prevent a dead loop inside mbedtls_exchange_data(). */
+        return ret;
+    } else if (expected_fragments == 1) {
+        /* Used for TLS/DTLS and the message size lower than MFL */
+        TEST_ASSERT(ret == buf_len ||
+                    ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                    ret == MBEDTLS_ERR_SSL_WANT_WRITE);
+    } else {
+        /* Used for TLS and the message size larger than MFL */
+        TEST_ASSERT(expected_fragments > 1);
+        TEST_ASSERT((ret >= 0 && ret <= buf_len) ||
+                    ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                    ret == MBEDTLS_ERR_SSL_WANT_WRITE);
+    }
+
+    return 0;
+
+exit:
+    /* Some of the tests failed */
+    return -1;
+}
+
+/*
+ * Read application data and increase read counter and fragments counter
+ * if necessary.
+ */
+int mbedtls_ssl_read_fragment(mbedtls_ssl_context *ssl, unsigned char *buf,
+                              int buf_len, int *read,
+                              int *fragments, const int expected_fragments)
+{
+    /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
+     * a valid no-op for TLS connections. */
+    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
+        TEST_ASSERT(mbedtls_ssl_read(ssl, NULL, 0) == 0);
+    }
+
+    int ret = mbedtls_ssl_read(ssl, buf + *read, buf_len - *read);
+    if (ret > 0) {
+        (*fragments)++;
+        *read += ret;
+    }
+
+    if (expected_fragments == 0) {
+        TEST_ASSERT(ret == 0);
+    } else if (expected_fragments == 1) {
+        TEST_ASSERT(ret == buf_len ||
+                    ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                    ret == MBEDTLS_ERR_SSL_WANT_WRITE);
+    } else {
+        TEST_ASSERT(expected_fragments > 1);
+        TEST_ASSERT((ret >= 0 && ret <= buf_len) ||
+                    ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                    ret == MBEDTLS_ERR_SSL_WANT_WRITE);
+    }
+
+    return 0;
+
+exit:
+    /* Some of the tests failed */
+    return -1;
+}
+
+/*
+ * Helper function setting up inverse record transformations
+ * using given cipher, hash, EtM mode, authentication tag length,
+ * and version.
+ */
+
+#define CHK(x)                                  \
+    do                                          \
+    {                                           \
+        if (!(x))                               \
+        {                                       \
+            ret = -1;                           \
+            goto cleanup;                       \
+        }                                       \
+    } while (0)
+
+void set_ciphersuite(mbedtls_ssl_config *conf, const char *cipher,
+                     int *forced_ciphersuite)
+{
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+    forced_ciphersuite[0] = mbedtls_ssl_get_ciphersuite_id(cipher);
+    forced_ciphersuite[1] = 0;
+
+    ciphersuite_info =
+        mbedtls_ssl_ciphersuite_from_id(forced_ciphersuite[0]);
+
+    TEST_ASSERT(ciphersuite_info != NULL);
+    TEST_ASSERT(ciphersuite_info->min_tls_version <= conf->max_tls_version);
+    TEST_ASSERT(ciphersuite_info->max_tls_version >= conf->min_tls_version);
+
+    if (conf->max_tls_version > ciphersuite_info->max_tls_version) {
+        conf->max_tls_version = ciphersuite_info->max_tls_version;
+    }
+    if (conf->min_tls_version < ciphersuite_info->min_tls_version) {
+        conf->min_tls_version = ciphersuite_info->min_tls_version;
+    }
+
+    mbedtls_ssl_conf_ciphersuites(conf, forced_ciphersuite);
+
+exit:
+    return;
+}
+
+int psk_dummy_callback(void *p_info, mbedtls_ssl_context *ssl,
+                       const unsigned char *name, size_t name_len)
+{
+    (void) p_info;
+    (void) ssl;
+    (void) name;
+    (void) name_len;
+
+    return 0;
+}
+
+#if MBEDTLS_SSL_CID_OUT_LEN_MAX > MBEDTLS_SSL_CID_IN_LEN_MAX
+#define SSL_CID_LEN_MIN MBEDTLS_SSL_CID_IN_LEN_MAX
+#else
+#define SSL_CID_LEN_MIN MBEDTLS_SSL_CID_OUT_LEN_MAX
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
+    defined(MBEDTLS_CIPHER_MODE_CBC) && defined(MBEDTLS_AES_C)
+int mbedtls_test_psa_cipher_encrypt_helper(mbedtls_ssl_transform *transform,
+                                           const unsigned char *iv,
+                                           size_t iv_len,
+                                           const unsigned char *input,
+                                           size_t ilen,
+                                           unsigned char *output,
+                                           size_t *olen)
+{
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT;
+    size_t part_len;
+
+    status = psa_cipher_encrypt_setup(&cipher_op,
+                                      transform->psa_key_enc,
+                                      transform->psa_alg);
+
+    if (status != PSA_SUCCESS) {
+        return PSA_TO_MBEDTLS_ERR(status);
+    }
+
+    status = psa_cipher_set_iv(&cipher_op, iv, iv_len);
+
+    if (status != PSA_SUCCESS) {
+        return PSA_TO_MBEDTLS_ERR(status);
+    }
+
+    status = psa_cipher_update(&cipher_op, input, ilen, output, ilen, olen);
+
+    if (status != PSA_SUCCESS) {
+        return PSA_TO_MBEDTLS_ERR(status);
+    }
+
+    status = psa_cipher_finish(&cipher_op, output + *olen, ilen - *olen,
+                               &part_len);
+
+    if (status != PSA_SUCCESS) {
+        return PSA_TO_MBEDTLS_ERR(status);
+    }
+
+    *olen += part_len;
+    return 0;
+#else
+    return mbedtls_cipher_crypt(&transform->cipher_ctx_enc,
+                                iv, iv_len, input, ilen, output, olen);
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 && MBEDTLS_CIPHER_MODE_CBC &&
+          MBEDTLS_AES_C */
+
+int mbedtls_test_ssl_build_transforms(mbedtls_ssl_transform *t_in,
+                                      mbedtls_ssl_transform *t_out,
+                                      int cipher_type, int hash_id,
+                                      int etm, int tag_mode,
+                                      mbedtls_ssl_protocol_version tls_version,
+                                      size_t cid0_len,
+                                      size_t cid1_len)
+{
+    mbedtls_cipher_info_t const *cipher_info;
+    int ret = 0;
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    psa_key_type_t key_type;
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_algorithm_t alg;
+    size_t key_bits;
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+#endif
+
+    size_t keylen, maclen, ivlen;
+    unsigned char *key0 = NULL, *key1 = NULL;
+    unsigned char *md0 = NULL, *md1 = NULL;
+    unsigned char iv_enc[16], iv_dec[16];
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+    unsigned char cid0[SSL_CID_LEN_MIN];
+    unsigned char cid1[SSL_CID_LEN_MIN];
+
+    mbedtls_test_rnd_std_rand(NULL, cid0, sizeof(cid0));
+    mbedtls_test_rnd_std_rand(NULL, cid1, sizeof(cid1));
+#else
+    ((void) cid0_len);
+    ((void) cid1_len);
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+    maclen = 0;
+
+    /* Pick cipher */
+    cipher_info = mbedtls_cipher_info_from_type(cipher_type);
+    CHK(cipher_info != NULL);
+    CHK(cipher_info->iv_size <= 16);
+    CHK(cipher_info->key_bitlen % 8 == 0);
+
+    /* Pick keys */
+    keylen = cipher_info->key_bitlen / 8;
+    /* Allocate `keylen + 1` bytes to ensure that we get
+     * a non-NULL pointers from `mbedtls_calloc` even if
+     * `keylen == 0` in the case of the NULL cipher. */
+    CHK((key0 = mbedtls_calloc(1, keylen + 1)) != NULL);
+    CHK((key1 = mbedtls_calloc(1, keylen + 1)) != NULL);
+    memset(key0, 0x1, keylen);
+    memset(key1, 0x2, keylen);
+
+#if !defined(MBEDTLS_USE_PSA_CRYPTO)
+    /* Setup cipher contexts */
+    CHK(mbedtls_cipher_setup(&t_in->cipher_ctx_enc,  cipher_info) == 0);
+    CHK(mbedtls_cipher_setup(&t_in->cipher_ctx_dec,  cipher_info) == 0);
+    CHK(mbedtls_cipher_setup(&t_out->cipher_ctx_enc, cipher_info) == 0);
+    CHK(mbedtls_cipher_setup(&t_out->cipher_ctx_dec, cipher_info) == 0);
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    if (cipher_info->mode == MBEDTLS_MODE_CBC) {
+        CHK(mbedtls_cipher_set_padding_mode(&t_in->cipher_ctx_enc,
+                                            MBEDTLS_PADDING_NONE) == 0);
+        CHK(mbedtls_cipher_set_padding_mode(&t_in->cipher_ctx_dec,
+                                            MBEDTLS_PADDING_NONE) == 0);
+        CHK(mbedtls_cipher_set_padding_mode(&t_out->cipher_ctx_enc,
+                                            MBEDTLS_PADDING_NONE) == 0);
+        CHK(mbedtls_cipher_set_padding_mode(&t_out->cipher_ctx_dec,
+                                            MBEDTLS_PADDING_NONE) == 0);
+    }
+#endif /* MBEDTLS_CIPHER_MODE_CBC */
+
+    CHK(mbedtls_cipher_setkey(&t_in->cipher_ctx_enc, key0,
+                              keylen << 3, MBEDTLS_ENCRYPT) == 0);
+    CHK(mbedtls_cipher_setkey(&t_in->cipher_ctx_dec, key1,
+                              keylen << 3, MBEDTLS_DECRYPT) == 0);
+    CHK(mbedtls_cipher_setkey(&t_out->cipher_ctx_enc, key1,
+                              keylen << 3, MBEDTLS_ENCRYPT) == 0);
+    CHK(mbedtls_cipher_setkey(&t_out->cipher_ctx_dec, key0,
+                              keylen << 3, MBEDTLS_DECRYPT) == 0);
+#endif
+
+    /* Setup MAC contexts */
+#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
+    if (cipher_info->mode == MBEDTLS_MODE_CBC ||
+        cipher_info->mode == MBEDTLS_MODE_STREAM) {
+#if !defined(MBEDTLS_USE_PSA_CRYPTO)
+        mbedtls_md_info_t const *md_info = mbedtls_md_info_from_type(hash_id);
+        CHK(md_info != NULL);
+#endif
+        maclen = mbedtls_hash_info_get_size(hash_id);
+        CHK(maclen != 0);
+        /* Pick hash keys */
+        CHK((md0 = mbedtls_calloc(1, maclen)) != NULL);
+        CHK((md1 = mbedtls_calloc(1, maclen)) != NULL);
+        memset(md0, 0x5, maclen);
+        memset(md1, 0x6, maclen);
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+        alg = mbedtls_hash_info_psa_from_md(hash_id);
+
+        CHK(alg != 0);
+
+        t_out->psa_mac_alg = PSA_ALG_HMAC(alg);
+        t_in->psa_mac_alg = PSA_ALG_HMAC(alg);
+        t_in->psa_mac_enc = MBEDTLS_SVC_KEY_ID_INIT;
+        t_out->psa_mac_enc = MBEDTLS_SVC_KEY_ID_INIT;
+        t_in->psa_mac_dec = MBEDTLS_SVC_KEY_ID_INIT;
+        t_out->psa_mac_dec = MBEDTLS_SVC_KEY_ID_INIT;
+
+        psa_reset_key_attributes(&attributes);
+        psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_MESSAGE);
+        psa_set_key_algorithm(&attributes, PSA_ALG_HMAC(alg));
+        psa_set_key_type(&attributes, PSA_KEY_TYPE_HMAC);
+
+        CHK(psa_import_key(&attributes,
+                           md0, maclen,
+                           &t_in->psa_mac_enc) == PSA_SUCCESS);
+
+        CHK(psa_import_key(&attributes,
+                           md1, maclen,
+                           &t_out->psa_mac_enc) == PSA_SUCCESS);
+
+        if (cipher_info->mode == MBEDTLS_MODE_STREAM ||
+            etm == MBEDTLS_SSL_ETM_DISABLED) {
+            /* mbedtls_ct_hmac() requires the key to be exportable */
+            psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_EXPORT |
+                                    PSA_KEY_USAGE_VERIFY_HASH);
+        } else {
+            psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_HASH);
+        }
+
+        CHK(psa_import_key(&attributes,
+                           md1, maclen,
+                           &t_in->psa_mac_dec) == PSA_SUCCESS);
+
+        CHK(psa_import_key(&attributes,
+                           md0, maclen,
+                           &t_out->psa_mac_dec) == PSA_SUCCESS);
+#else
+        CHK(mbedtls_md_setup(&t_out->md_ctx_enc, md_info, 1) == 0);
+        CHK(mbedtls_md_setup(&t_out->md_ctx_dec, md_info, 1) == 0);
+        CHK(mbedtls_md_setup(&t_in->md_ctx_enc,  md_info, 1) == 0);
+        CHK(mbedtls_md_setup(&t_in->md_ctx_dec,  md_info, 1) == 0);
+
+        CHK(mbedtls_md_hmac_starts(&t_in->md_ctx_enc,
+                                   md0, maclen) == 0);
+        CHK(mbedtls_md_hmac_starts(&t_in->md_ctx_dec,
+                                   md1, maclen) == 0);
+        CHK(mbedtls_md_hmac_starts(&t_out->md_ctx_enc,
+                                   md1, maclen) == 0);
+        CHK(mbedtls_md_hmac_starts(&t_out->md_ctx_dec,
+                                   md0, maclen) == 0);
+#endif
+    }
+#else
+    ((void) hash_id);
+#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
+
+
+    /* Pick IV's (regardless of whether they
+     * are being used by the transform). */
+    ivlen = cipher_info->iv_size;
+    memset(iv_enc, 0x3, sizeof(iv_enc));
+    memset(iv_dec, 0x4, sizeof(iv_dec));
+
+    /*
+     * Setup transforms
+     */
+
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) && \
+    defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
+    t_out->encrypt_then_mac = etm;
+    t_in->encrypt_then_mac = etm;
+#else
+    ((void) etm);
+#endif
+
+    t_out->tls_version = tls_version;
+    t_in->tls_version = tls_version;
+    t_out->ivlen = ivlen;
+    t_in->ivlen = ivlen;
+
+    switch (cipher_info->mode) {
+        case MBEDTLS_MODE_GCM:
+        case MBEDTLS_MODE_CCM:
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+            if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
+                t_out->fixed_ivlen = 12;
+                t_in->fixed_ivlen  = 12;
+            } else
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
+            {
+                t_out->fixed_ivlen = 4;
+                t_in->fixed_ivlen = 4;
+            }
+            t_out->maclen = 0;
+            t_in->maclen = 0;
+            switch (tag_mode) {
+                case 0: /* Full tag */
+                    t_out->taglen = 16;
+                    t_in->taglen = 16;
+                    break;
+                case 1: /* Partial tag */
+                    t_out->taglen = 8;
+                    t_in->taglen = 8;
+                    break;
+                default:
+                    ret = 1;
+                    goto cleanup;
+            }
+            break;
+
+        case MBEDTLS_MODE_CHACHAPOLY:
+            t_out->fixed_ivlen = 12;
+            t_in->fixed_ivlen = 12;
+            t_out->maclen = 0;
+            t_in->maclen = 0;
+            switch (tag_mode) {
+                case 0: /* Full tag */
+                    t_out->taglen = 16;
+                    t_in->taglen = 16;
+                    break;
+                case 1: /* Partial tag */
+                    t_out->taglen = 8;
+                    t_in->taglen = 8;
+                    break;
+                default:
+                    ret = 1;
+                    goto cleanup;
+            }
+            break;
+
+        case MBEDTLS_MODE_STREAM:
+        case MBEDTLS_MODE_CBC:
+            t_out->fixed_ivlen = 0; /* redundant, must be 0 */
+            t_in->fixed_ivlen = 0;  /* redundant, must be 0 */
+            t_out->taglen = 0;
+            t_in->taglen = 0;
+            switch (tag_mode) {
+                case 0: /* Full tag */
+                    t_out->maclen = maclen;
+                    t_in->maclen = maclen;
+                    break;
+                default:
+                    ret = 1;
+                    goto cleanup;
+            }
+            break;
+        default:
+            ret = 1;
+            goto cleanup;
+            break;
+    }
+
+    /* Setup IV's */
+
+    memcpy(&t_in->iv_dec, iv_dec, sizeof(iv_dec));
+    memcpy(&t_in->iv_enc, iv_enc, sizeof(iv_enc));
+    memcpy(&t_out->iv_dec, iv_enc, sizeof(iv_enc));
+    memcpy(&t_out->iv_enc, iv_dec, sizeof(iv_dec));
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+    /* Add CID */
+    memcpy(&t_in->in_cid,  cid0, cid0_len);
+    memcpy(&t_in->out_cid, cid1, cid1_len);
+    t_in->in_cid_len = cid0_len;
+    t_in->out_cid_len = cid1_len;
+    memcpy(&t_out->in_cid,  cid1, cid1_len);
+    memcpy(&t_out->out_cid, cid0, cid0_len);
+    t_out->in_cid_len = cid1_len;
+    t_out->out_cid_len = cid0_len;
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+    status = mbedtls_ssl_cipher_to_psa(cipher_type,
+                                       t_in->taglen,
+                                       &alg,
+                                       &key_type,
+                                       &key_bits);
+
+    if (status != PSA_SUCCESS) {
+        ret = PSA_TO_MBEDTLS_ERR(status);
+        goto cleanup;
+    }
+
+    t_in->psa_alg = alg;
+    t_out->psa_alg = alg;
+
+    if (alg != MBEDTLS_SSL_NULL_CIPHER) {
+        psa_reset_key_attributes(&attributes);
+        psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_ENCRYPT);
+        psa_set_key_algorithm(&attributes, alg);
+        psa_set_key_type(&attributes, key_type);
+
+        status = psa_import_key(&attributes,
+                                key0,
+                                PSA_BITS_TO_BYTES(key_bits),
+                                &t_in->psa_key_enc);
+
+        if (status != PSA_SUCCESS) {
+            ret = PSA_TO_MBEDTLS_ERR(status);
+            goto cleanup;
+        }
+
+        status = psa_import_key(&attributes,
+                                key1,
+                                PSA_BITS_TO_BYTES(key_bits),
+                                &t_out->psa_key_enc);
+
+        if (status != PSA_SUCCESS) {
+            ret = PSA_TO_MBEDTLS_ERR(status);
+            goto cleanup;
+        }
+
+        psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DECRYPT);
+
+        status = psa_import_key(&attributes,
+                                key1,
+                                PSA_BITS_TO_BYTES(key_bits),
+                                &t_in->psa_key_dec);
+
+        if (status != PSA_SUCCESS) {
+            ret = PSA_TO_MBEDTLS_ERR(status);
+            goto cleanup;
+        }
+
+        status = psa_import_key(&attributes,
+                                key0,
+                                PSA_BITS_TO_BYTES(key_bits),
+                                &t_out->psa_key_dec);
+
+        if (status != PSA_SUCCESS) {
+            ret = PSA_TO_MBEDTLS_ERR(status);
+            goto cleanup;
+        }
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+cleanup:
+
+    mbedtls_free(key0);
+    mbedtls_free(key1);
+
+    mbedtls_free(md0);
+    mbedtls_free(md1);
+
+    return ret;
+}
+
+/*
+ * Populate a session structure for serialization tests.
+ * Choose dummy values, mostly non-0 to distinguish from the init default.
+ */
+int mbedtls_test_ssl_tls12_populate_session(mbedtls_ssl_session *session,
+                                            int ticket_len,
+                                            const char *crt_file)
+{
+#if defined(MBEDTLS_HAVE_TIME)
+    session->start = mbedtls_time(NULL) - 42;
+#endif
+    session->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
+    session->ciphersuite = 0xabcd;
+    session->id_len = sizeof(session->id);
+    memset(session->id, 66, session->id_len);
+    memset(session->master, 17, sizeof(session->master));
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED) && defined(MBEDTLS_FS_IO)
+    if (crt_file != NULL && strlen(crt_file) != 0) {
+        mbedtls_x509_crt tmp_crt;
+        int ret;
+
+        mbedtls_x509_crt_init(&tmp_crt);
+        ret = mbedtls_x509_crt_parse_file(&tmp_crt, crt_file);
+        if (ret != 0) {
+            return ret;
+        }
+
+#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+        /* Move temporary CRT. */
+        session->peer_cert = mbedtls_calloc(1, sizeof(*session->peer_cert));
+        if (session->peer_cert == NULL) {
+            return -1;
+        }
+        *session->peer_cert = tmp_crt;
+        memset(&tmp_crt, 0, sizeof(tmp_crt));
+#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+        /* Calculate digest of temporary CRT. */
+        session->peer_cert_digest =
+            mbedtls_calloc(1, MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN);
+        if (session->peer_cert_digest == NULL) {
+            return -1;
+        }
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+        psa_algorithm_t psa_alg = mbedtls_hash_info_psa_from_md(
+            MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE);
+        size_t hash_size = 0;
+        psa_status_t status = psa_hash_compute(
+            psa_alg, tmp_crt.raw.p,
+            tmp_crt.raw.len,
+            session->peer_cert_digest,
+            MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN,
+            &hash_size);
+        ret = PSA_TO_MBEDTLS_ERR(status);
+#else
+        ret = mbedtls_md(mbedtls_md_info_from_type(
+                             MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE),
+                         tmp_crt.raw.p, tmp_crt.raw.len,
+                         session->peer_cert_digest);
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+        if (ret != 0) {
+            return ret;
+        }
+        session->peer_cert_digest_type =
+            MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE;
+        session->peer_cert_digest_len =
+            MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN;
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
+        mbedtls_x509_crt_free(&tmp_crt);
+    }
+#else /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED && MBEDTLS_FS_IO */
+    (void) crt_file;
+#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED && MBEDTLS_FS_IO */
+    session->verify_result = 0xdeadbeef;
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
+    if (ticket_len != 0) {
+        session->ticket = mbedtls_calloc(1, ticket_len);
+        if (session->ticket == NULL) {
+            return -1;
+        }
+        memset(session->ticket, 33, ticket_len);
+    }
+    session->ticket_len = ticket_len;
+    session->ticket_lifetime = 86401;
+#else
+    (void) ticket_len;
+#endif
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    session->mfl_code = 1;
+#endif
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+    session->encrypt_then_mac = 1;
+#endif
+
+    return 0;
+}
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+int mbedtls_test_ssl_tls13_populate_session(mbedtls_ssl_session *session,
+                                            int ticket_len,
+                                            int endpoint_type)
+{
+    ((void) ticket_len);
+    session->tls_version = MBEDTLS_SSL_VERSION_TLS1_3;
+    session->endpoint = endpoint_type == MBEDTLS_SSL_IS_CLIENT ?
+                        MBEDTLS_SSL_IS_CLIENT : MBEDTLS_SSL_IS_SERVER;
+    session->ciphersuite = 0xabcd;
+    session->ticket_age_add = 0x87654321;
+    session->ticket_flags = 0x7;
+
+    session->resumption_key_len = 32;
+    memset(session->resumption_key, 0x99, sizeof(session->resumption_key));
+
+#if defined(MBEDTLS_HAVE_TIME)
+    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
+        session->start = mbedtls_time(NULL) - 42;
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_CLI_C)
+    if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
+#if defined(MBEDTLS_HAVE_TIME)
+        session->ticket_received = mbedtls_time(NULL) - 40;
+#endif
+        session->ticket_lifetime = 0xfedcba98;
+
+        session->ticket_len = ticket_len;
+        if (ticket_len != 0) {
+            session->ticket = mbedtls_calloc(1, ticket_len);
+            if (session->ticket == NULL) {
+                return -1;
+            }
+            memset(session->ticket, 33, ticket_len);
+        }
+    }
+#endif /* MBEDTLS_SSL_CLI_C */
+
+    return 0;
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
+
+/*
+ * Perform data exchanging between \p ssl_1 and \p ssl_2 and check if the
+ * message was sent in the correct number of fragments.
+ *
+ * /p ssl_1 and /p ssl_2    Endpoints represented by mbedtls_ssl_context. Both
+ *                          of them must be initialized and connected
+ *                          beforehand.
+ * /p msg_len_1 and /p msg_len_2 specify the size of the message to send.
+ * /p expected_fragments_1 and /p expected_fragments_2 determine in how many
+ *                          fragments the message should be sent.
+ *      expected_fragments is 0: can be used for DTLS testing while the message
+ *                          size is larger than MFL. In that case the message
+ *                          cannot be fragmented and sent to the second
+ *                          endpoint.
+ *                          This value can be used for negative tests.
+ *      expected_fragments is 1: can be used for TLS/DTLS testing while the
+ *                          message size is below MFL
+ *      expected_fragments > 1: can be used for TLS testing while the message
+ *                          size is larger than MFL
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_exchange_data(mbedtls_ssl_context *ssl_1,
+                          int msg_len_1, const int expected_fragments_1,
+                          mbedtls_ssl_context *ssl_2,
+                          int msg_len_2, const int expected_fragments_2)
+{
+    unsigned char *msg_buf_1 = malloc(msg_len_1);
+    unsigned char *msg_buf_2 = malloc(msg_len_2);
+    unsigned char *in_buf_1  = malloc(msg_len_2);
+    unsigned char *in_buf_2  = malloc(msg_len_1);
+    int msg_type, ret = -1;
+
+    /* Perform this test with two message types. At first use a message
+     * consisting of only 0x00 for the client and only 0xFF for the server.
+     * At the second time use message with generated data */
+    for (msg_type = 0; msg_type < 2; msg_type++) {
+        int written_1 = 0;
+        int written_2 = 0;
+        int read_1 = 0;
+        int read_2 = 0;
+        int fragments_1 = 0;
+        int fragments_2 = 0;
+
+        if (msg_type == 0) {
+            memset(msg_buf_1, 0x00, msg_len_1);
+            memset(msg_buf_2, 0xff, msg_len_2);
+        } else {
+            int i, j = 0;
+            for (i = 0; i < msg_len_1; i++) {
+                msg_buf_1[i] = j++ & 0xFF;
+            }
+            for (i = 0; i < msg_len_2; i++) {
+                msg_buf_2[i] = (j -= 5) & 0xFF;
+            }
+        }
+
+        while (read_1 < msg_len_2 || read_2 < msg_len_1) {
+            /* ssl_1 sending */
+            if (msg_len_1 > written_1) {
+                ret = mbedtls_ssl_write_fragment(ssl_1, msg_buf_1,
+                                                 msg_len_1, &written_1,
+                                                 expected_fragments_1);
+                if (expected_fragments_1 == 0) {
+                    /* This error is expected when the message is too large and
+                     * cannot be fragmented */
+                    TEST_ASSERT(ret == MBEDTLS_ERR_SSL_BAD_INPUT_DATA);
+                    msg_len_1 = 0;
+                } else {
+                    TEST_ASSERT(ret == 0);
+                }
+            }
+
+            /* ssl_2 sending */
+            if (msg_len_2 > written_2) {
+                ret = mbedtls_ssl_write_fragment(ssl_2, msg_buf_2,
+                                                 msg_len_2, &written_2,
+                                                 expected_fragments_2);
+                if (expected_fragments_2 == 0) {
+                    /* This error is expected when the message is too large and
+                     * cannot be fragmented */
+                    TEST_ASSERT(ret == MBEDTLS_ERR_SSL_BAD_INPUT_DATA);
+                    msg_len_2 = 0;
+                } else {
+                    TEST_ASSERT(ret == 0);
+                }
+            }
+
+            /* ssl_1 reading */
+            if (read_1 < msg_len_2) {
+                ret = mbedtls_ssl_read_fragment(ssl_1, in_buf_1,
+                                                msg_len_2, &read_1,
+                                                &fragments_2,
+                                                expected_fragments_2);
+                TEST_ASSERT(ret == 0);
+            }
+
+            /* ssl_2 reading */
+            if (read_2 < msg_len_1) {
+                ret = mbedtls_ssl_read_fragment(ssl_2, in_buf_2,
+                                                msg_len_1, &read_2,
+                                                &fragments_1,
+                                                expected_fragments_1);
+                TEST_ASSERT(ret == 0);
+            }
+        }
+
+        ret = -1;
+        TEST_ASSERT(0 == memcmp(msg_buf_1, in_buf_2, msg_len_1));
+        TEST_ASSERT(0 == memcmp(msg_buf_2, in_buf_1, msg_len_2));
+        TEST_ASSERT(fragments_1 == expected_fragments_1);
+        TEST_ASSERT(fragments_2 == expected_fragments_2);
+    }
+
+    ret = 0;
+
+exit:
+    free(msg_buf_1);
+    free(in_buf_1);
+    free(msg_buf_2);
+    free(in_buf_2);
+
+    return ret;
+}
+
+/*
+ * Perform data exchanging between \p ssl_1 and \p ssl_2. Both of endpoints
+ * must be initialized and connected beforehand.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int exchange_data(mbedtls_ssl_context *ssl_1,
+                  mbedtls_ssl_context *ssl_2)
+{
+    return mbedtls_exchange_data(ssl_1, 256, 1,
+                                 ssl_2, 256, 1);
+}
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+static int check_ssl_version(
+    mbedtls_ssl_protocol_version expected_negotiated_version,
+    const mbedtls_ssl_context *ssl)
+{
+    const char *version_string = mbedtls_ssl_get_version(ssl);
+    mbedtls_ssl_protocol_version version_number =
+        mbedtls_ssl_get_version_number(ssl);
+
+    TEST_EQUAL(ssl->tls_version, expected_negotiated_version);
+
+    if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
+        TEST_EQUAL(version_string[0], 'D');
+        ++version_string;
+    }
+
+    switch (expected_negotiated_version) {
+        case MBEDTLS_SSL_VERSION_TLS1_2:
+            TEST_EQUAL(version_number, MBEDTLS_SSL_VERSION_TLS1_2);
+            TEST_ASSERT(strcmp(version_string, "TLSv1.2") == 0);
+            break;
+
+        case MBEDTLS_SSL_VERSION_TLS1_3:
+            TEST_EQUAL(version_number, MBEDTLS_SSL_VERSION_TLS1_3);
+            TEST_ASSERT(strcmp(version_string, "TLSv1.3") == 0);
+            break;
+
+        default:
+            TEST_ASSERT(
+                !"Version check not implemented for this protocol version");
+    }
+
+    return 1;
+
+exit:
+    return 0;
+}
+#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
+
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+void mbedtls_test_ssl_perform_handshake(
+    mbedtls_test_handshake_test_options *options)
+{
+    /* forced_ciphersuite needs to last until the end of the handshake */
+    int forced_ciphersuite[2];
+    enum { BUFFSIZE = 17000 };
+    mbedtls_test_ssl_endpoint client, server;
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_PSK_ENABLED)
+    const char *psk_identity = "foo";
+#endif
+#if defined(MBEDTLS_TIMING_C)
+    mbedtls_timing_delay_context timer_client, timer_server;
+#endif
+#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
+    unsigned char *context_buf = NULL;
+    size_t context_buf_len;
+#endif
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    int ret = -1;
+#endif
+    int expected_handshake_result = options->expected_handshake_result;
+
+    USE_PSA_INIT();
+    mbedtls_platform_zeroize(&client, sizeof(client));
+    mbedtls_platform_zeroize(&server, sizeof(server));
+    mbedtls_test_ssl_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+    mbedtls_test_message_socket_init(&server_context);
+    mbedtls_test_message_socket_init(&client_context);
+
+    /* Client side */
+    if (options->dtls != 0) {
+        TEST_ASSERT(mbedtls_test_ssl_endpoint_init(&client,
+                                                   MBEDTLS_SSL_IS_CLIENT,
+                                                   options, &client_context,
+                                                   &client_queue,
+                                                   &server_queue, NULL) == 0);
+#if defined(MBEDTLS_TIMING_C)
+        mbedtls_ssl_set_timer_cb(&client.ssl, &timer_client,
+                                 mbedtls_timing_set_delay,
+                                 mbedtls_timing_get_delay);
+#endif
+    } else {
+        TEST_ASSERT(mbedtls_test_ssl_endpoint_init(&client,
+                                                   MBEDTLS_SSL_IS_CLIENT,
+                                                   options, NULL, NULL,
+                                                   NULL, NULL) == 0);
+    }
+
+    if (options->client_min_version != MBEDTLS_SSL_VERSION_UNKNOWN) {
+        mbedtls_ssl_conf_min_tls_version(&client.conf,
+                                         options->client_min_version);
+    }
+
+    if (options->client_max_version != MBEDTLS_SSL_VERSION_UNKNOWN) {
+        mbedtls_ssl_conf_max_tls_version(&client.conf,
+                                         options->client_max_version);
+    }
+
+    if (strlen(options->cipher) > 0) {
+        set_ciphersuite(&client.conf, options->cipher, forced_ciphersuite);
+    }
+
+#if defined(MBEDTLS_DEBUG_C)
+    if (options->cli_log_fun) {
+        mbedtls_debug_set_threshold(4);
+        mbedtls_ssl_conf_dbg(&client.conf, options->cli_log_fun,
+                             options->cli_log_obj);
+    }
+#endif
+
+    /* Server side */
+    if (options->dtls != 0) {
+        TEST_ASSERT(mbedtls_test_ssl_endpoint_init(&server,
+                                                   MBEDTLS_SSL_IS_SERVER,
+                                                   options, &server_context,
+                                                   &server_queue,
+                                                   &client_queue, NULL) == 0);
+#if defined(MBEDTLS_TIMING_C)
+        mbedtls_ssl_set_timer_cb(&server.ssl, &timer_server,
+                                 mbedtls_timing_set_delay,
+                                 mbedtls_timing_get_delay);
+#endif
+    } else {
+        TEST_ASSERT(mbedtls_test_ssl_endpoint_init(&server,
+                                                   MBEDTLS_SSL_IS_SERVER,
+                                                   options, NULL, NULL, NULL,
+                                                   NULL) == 0);
+    }
+
+    mbedtls_ssl_conf_authmode(&server.conf, options->srv_auth_mode);
+
+    if (options->server_min_version != MBEDTLS_SSL_VERSION_UNKNOWN) {
+        mbedtls_ssl_conf_min_tls_version(&server.conf,
+                                         options->server_min_version);
+    }
+
+    if (options->server_max_version != MBEDTLS_SSL_VERSION_UNKNOWN) {
+        mbedtls_ssl_conf_max_tls_version(&server.conf,
+                                         options->server_max_version);
+    }
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    TEST_ASSERT(mbedtls_ssl_conf_max_frag_len(&(server.conf),
+                                              (unsigned char) options->mfl)
+                == 0);
+    TEST_ASSERT(mbedtls_ssl_conf_max_frag_len(&(client.conf),
+                                              (unsigned char) options->mfl)
+                == 0);
+#else
+    TEST_ASSERT(MBEDTLS_SSL_MAX_FRAG_LEN_NONE == options->mfl);
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_PSK_ENABLED)
+    if (options->psk_str != NULL && options->psk_str->len > 0) {
+        TEST_ASSERT(mbedtls_ssl_conf_psk(
+                        &client.conf, options->psk_str->x,
+                        options->psk_str->len,
+                        (const unsigned char *) psk_identity,
+                        strlen(psk_identity)) == 0);
+
+        TEST_ASSERT(mbedtls_ssl_conf_psk(
+                        &server.conf, options->psk_str->x,
+                        options->psk_str->len,
+                        (const unsigned char *) psk_identity,
+                        strlen(psk_identity)) == 0);
+#if defined(MBEDTLS_SSL_SRV_C)
+        mbedtls_ssl_conf_psk_cb(&server.conf, psk_dummy_callback, NULL);
+#endif
+    }
+#endif
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if (options->renegotiate) {
+        mbedtls_ssl_conf_renegotiation(&(server.conf),
+                                       MBEDTLS_SSL_RENEGOTIATION_ENABLED);
+        mbedtls_ssl_conf_renegotiation(&(client.conf),
+                                       MBEDTLS_SSL_RENEGOTIATION_ENABLED);
+
+        mbedtls_ssl_conf_legacy_renegotiation(&(server.conf),
+                                              options->legacy_renegotiation);
+        mbedtls_ssl_conf_legacy_renegotiation(&(client.conf),
+                                              options->legacy_renegotiation);
+    }
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+#if defined(MBEDTLS_DEBUG_C)
+    if (options->srv_log_fun) {
+        mbedtls_debug_set_threshold(4);
+        mbedtls_ssl_conf_dbg(&server.conf, options->srv_log_fun,
+                             options->srv_log_obj);
+    }
+#endif
+
+    TEST_ASSERT(mbedtls_test_mock_socket_connect(&(client.socket),
+                                                 &(server.socket),
+                                                 BUFFSIZE) == 0);
+
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+    if (options->resize_buffers != 0) {
+        /* Ensure that the buffer sizes are appropriate before resizes */
+        TEST_ASSERT(client.ssl.out_buf_len == MBEDTLS_SSL_OUT_BUFFER_LEN);
+        TEST_ASSERT(client.ssl.in_buf_len == MBEDTLS_SSL_IN_BUFFER_LEN);
+        TEST_ASSERT(server.ssl.out_buf_len == MBEDTLS_SSL_OUT_BUFFER_LEN);
+        TEST_ASSERT(server.ssl.in_buf_len == MBEDTLS_SSL_IN_BUFFER_LEN);
+    }
+#endif
+
+    if (options->expected_negotiated_version == MBEDTLS_SSL_VERSION_UNKNOWN) {
+        expected_handshake_result = MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION;
+    }
+
+    TEST_ASSERT(mbedtls_test_move_handshake_to_state(&(client.ssl),
+                                                     &(server.ssl),
+                                                     MBEDTLS_SSL_HANDSHAKE_OVER)
+                ==  expected_handshake_result);
+
+    if (expected_handshake_result != 0) {
+        /* Connection will have failed by this point, skip to cleanup */
+        goto exit;
+    }
+
+    TEST_ASSERT(mbedtls_ssl_is_handshake_over(&client.ssl) == 1);
+
+    /* Make sure server state is moved to HANDSHAKE_OVER also. */
+    TEST_EQUAL(mbedtls_test_move_handshake_to_state(&(server.ssl),
+                                                    &(client.ssl),
+                                                    MBEDTLS_SSL_HANDSHAKE_OVER),
+               0);
+
+    TEST_ASSERT(mbedtls_ssl_is_handshake_over(&server.ssl) == 1);
+    /* Check that both sides have negotiated the expected version. */
+    mbedtls_test_set_step(0);
+    if (!check_ssl_version(options->expected_negotiated_version,
+                           &client.ssl)) {
+        goto exit;
+    }
+
+    mbedtls_test_set_step(1);
+    if (!check_ssl_version(options->expected_negotiated_version,
+                           &server.ssl)) {
+        goto exit;
+    }
+
+    if (options->expected_ciphersuite != 0) {
+        TEST_EQUAL(server.ssl.session->ciphersuite,
+                   options->expected_ciphersuite);
+    }
+
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+    if (options->resize_buffers != 0) {
+        /* A server, when using DTLS, might delay a buffer resize to happen
+         * after it receives a message, so we force it. */
+        TEST_ASSERT(exchange_data(&(client.ssl), &(server.ssl)) == 0);
+
+        TEST_ASSERT(client.ssl.out_buf_len ==
+                    mbedtls_ssl_get_output_buflen(&client.ssl));
+        TEST_ASSERT(client.ssl.in_buf_len ==
+                    mbedtls_ssl_get_input_buflen(&client.ssl));
+        TEST_ASSERT(server.ssl.out_buf_len ==
+                    mbedtls_ssl_get_output_buflen(&server.ssl));
+        TEST_ASSERT(server.ssl.in_buf_len ==
+                    mbedtls_ssl_get_input_buflen(&server.ssl));
+    }
+#endif
+
+    if (options->cli_msg_len != 0 || options->srv_msg_len != 0) {
+        /* Start data exchanging test */
+        TEST_ASSERT(mbedtls_exchange_data(&(client.ssl), options->cli_msg_len,
+                                          options->expected_cli_fragments,
+                                          &(server.ssl), options->srv_msg_len,
+                                          options->expected_srv_fragments)
+                    == 0);
+    }
+#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
+    if (options->serialize == 1) {
+        TEST_ASSERT(options->dtls == 1);
+
+        TEST_ASSERT(mbedtls_ssl_context_save(&(server.ssl), NULL,
+                                             0, &context_buf_len)
+                    == MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL);
+
+        context_buf = mbedtls_calloc(1, context_buf_len);
+        TEST_ASSERT(context_buf != NULL);
+
+        TEST_ASSERT(mbedtls_ssl_context_save(&(server.ssl), context_buf,
+                                             context_buf_len,
+                                             &context_buf_len)
+                    == 0);
+
+        mbedtls_ssl_free(&(server.ssl));
+        mbedtls_ssl_init(&(server.ssl));
+
+        TEST_ASSERT(mbedtls_ssl_setup(&(server.ssl), &(server.conf)) == 0);
+
+        mbedtls_ssl_set_bio(&(server.ssl), &server_context,
+                            mbedtls_test_mock_tcp_send_msg,
+                            mbedtls_test_mock_tcp_recv_msg,
+                            NULL);
+
+        mbedtls_ssl_set_user_data_p(&server.ssl, &server);
+
+#if defined(MBEDTLS_TIMING_C)
+        mbedtls_ssl_set_timer_cb(&server.ssl, &timer_server,
+                                 mbedtls_timing_set_delay,
+                                 mbedtls_timing_get_delay);
+#endif
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+        if (options->resize_buffers != 0) {
+            /* Ensure that the buffer sizes are appropriate before resizes */
+            TEST_ASSERT(server.ssl.out_buf_len == MBEDTLS_SSL_OUT_BUFFER_LEN);
+            TEST_ASSERT(server.ssl.in_buf_len == MBEDTLS_SSL_IN_BUFFER_LEN);
+        }
+#endif
+        TEST_ASSERT(mbedtls_ssl_context_load(&(server.ssl), context_buf,
+                                             context_buf_len) == 0);
+
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+        /* Validate buffer sizes after context deserialization */
+        if (options->resize_buffers != 0) {
+            TEST_ASSERT(server.ssl.out_buf_len ==
+                        mbedtls_ssl_get_output_buflen(&server.ssl));
+            TEST_ASSERT(server.ssl.in_buf_len ==
+                        mbedtls_ssl_get_input_buflen(&server.ssl));
+        }
+#endif
+        /* Retest writing/reading */
+        if (options->cli_msg_len != 0 || options->srv_msg_len != 0) {
+            TEST_ASSERT(mbedtls_exchange_data(
+                            &(client.ssl),
+                            options->cli_msg_len,
+                            options->expected_cli_fragments,
+                            &(server.ssl),
+                            options->srv_msg_len,
+                            options->expected_srv_fragments)
+                        == 0);
+        }
+    }
+#endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
+
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    if (options->renegotiate) {
+        /* Start test with renegotiation */
+        TEST_ASSERT(server.ssl.renego_status ==
+                    MBEDTLS_SSL_INITIAL_HANDSHAKE);
+        TEST_ASSERT(client.ssl.renego_status ==
+                    MBEDTLS_SSL_INITIAL_HANDSHAKE);
+
+        /* After calling this function for the server, it only sends a handshake
+         * request. All renegotiation should happen during data exchanging */
+        TEST_ASSERT(mbedtls_ssl_renegotiate(&(server.ssl)) == 0);
+        TEST_ASSERT(server.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_PENDING);
+        TEST_ASSERT(client.ssl.renego_status ==
+                    MBEDTLS_SSL_INITIAL_HANDSHAKE);
+
+        TEST_ASSERT(exchange_data(&(client.ssl), &(server.ssl)) == 0);
+        TEST_ASSERT(server.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_DONE);
+        TEST_ASSERT(client.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_DONE);
+
+        /* After calling mbedtls_ssl_renegotiate for the client,
+         * all renegotiation should happen inside this function.
+         * However in this test, we cannot perform simultaneous communication
+         * between client and server so this function will return waiting error
+         * on the socket. All rest of renegotiation should happen
+         * during data exchanging */
+        ret = mbedtls_ssl_renegotiate(&(client.ssl));
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+        if (options->resize_buffers != 0) {
+            /* Ensure that the buffer sizes are appropriate before resizes */
+            TEST_ASSERT(client.ssl.out_buf_len == MBEDTLS_SSL_OUT_BUFFER_LEN);
+            TEST_ASSERT(client.ssl.in_buf_len == MBEDTLS_SSL_IN_BUFFER_LEN);
+        }
+#endif
+        TEST_ASSERT(ret == 0 ||
+                    ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                    ret == MBEDTLS_ERR_SSL_WANT_WRITE);
+        TEST_ASSERT(server.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_DONE);
+        TEST_ASSERT(client.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS);
+
+        TEST_ASSERT(exchange_data(&(client.ssl), &(server.ssl)) == 0);
+        TEST_ASSERT(server.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_DONE);
+        TEST_ASSERT(client.ssl.renego_status ==
+                    MBEDTLS_SSL_RENEGOTIATION_DONE);
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+        /* Validate buffer sizes after renegotiation */
+        if (options->resize_buffers != 0) {
+            TEST_ASSERT(client.ssl.out_buf_len ==
+                        mbedtls_ssl_get_output_buflen(&client.ssl));
+            TEST_ASSERT(client.ssl.in_buf_len ==
+                        mbedtls_ssl_get_input_buflen(&client.ssl));
+            TEST_ASSERT(server.ssl.out_buf_len ==
+                        mbedtls_ssl_get_output_buflen(&server.ssl));
+            TEST_ASSERT(server.ssl.in_buf_len ==
+                        mbedtls_ssl_get_input_buflen(&server.ssl));
+        }
+#endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */
+    }
+#endif /* MBEDTLS_SSL_RENEGOTIATION */
+
+    TEST_ASSERT(mbedtls_ssl_conf_get_user_data_p(&client.conf) == &client);
+    TEST_ASSERT(mbedtls_ssl_get_user_data_p(&client.ssl) == &client);
+    TEST_ASSERT(mbedtls_ssl_conf_get_user_data_p(&server.conf) == &server);
+    TEST_ASSERT(mbedtls_ssl_get_user_data_p(&server.ssl) == &server);
+
+exit:
+    mbedtls_test_ssl_endpoint_free(&client,
+                                   options->dtls != 0 ?
+                                   &client_context : NULL);
+    mbedtls_test_ssl_endpoint_free(&server,
+                                   options->dtls != 0 ?
+                                   &server_context : NULL);
+#if defined(MBEDTLS_DEBUG_C)
+    if (options->cli_log_fun || options->srv_log_fun) {
+        mbedtls_debug_set_threshold(0);
+    }
+#endif
+#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
+    if (context_buf != NULL) {
+        mbedtls_free(context_buf);
+    }
+#endif
+    USE_PSA_DONE();
+}
+#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
+
+#if defined(MBEDTLS_TEST_HOOKS)
+/*
+ * Tweak vector lengths in a TLS 1.3 Certificate message
+ *
+ * \param[in]       buf    Buffer containing the Certificate message to tweak
+ * \param[in]]out]  end    End of the buffer to parse
+ * \param           tweak  Tweak identifier (from 1 to the number of tweaks).
+ * \param[out]  expected_result  Error code expected from the parsing function
+ * \param[out]  args  Arguments of the MBEDTLS_SSL_CHK_BUF_READ_PTR call that
+ *                    is expected to fail. All zeroes if no
+ *                    MBEDTLS_SSL_CHK_BUF_READ_PTR failure is expected.
+ */
+int tweak_tls13_certificate_msg_vector_len(
+    unsigned char *buf, unsigned char **end, int tweak,
+    int *expected_result, mbedtls_ssl_chk_buf_ptr_args *args)
+{
+/*
+ * The definition of the tweaks assume that the certificate list contains only
+ * one certificate.
+ */
+
+/*
+ * struct {
+ *     opaque cert_data<1..2^24-1>;
+ *     Extension extensions<0..2^16-1>;
+ * } CertificateEntry;
+ *
+ * struct {
+ *     opaque certificate_request_context<0..2^8-1>;
+ *     CertificateEntry certificate_list<0..2^24-1>;
+ * } Certificate;
+ */
+    unsigned char *p_certificate_request_context_len = buf;
+    size_t certificate_request_context_len = buf[0];
+
+    unsigned char *p_certificate_list_len =
+        buf + 1 + certificate_request_context_len;
+    unsigned char *certificate_list = p_certificate_list_len + 3;
+    size_t certificate_list_len =
+        MBEDTLS_GET_UINT24_BE(p_certificate_list_len, 0);
+
+    unsigned char *p_cert_data_len = certificate_list;
+    unsigned char *cert_data = p_cert_data_len + 3;
+    size_t cert_data_len = MBEDTLS_GET_UINT24_BE(p_cert_data_len, 0);
+
+    unsigned char *p_extensions_len = cert_data + cert_data_len;
+    unsigned char *extensions = p_extensions_len + 2;
+    size_t extensions_len = MBEDTLS_GET_UINT16_BE(p_extensions_len, 0);
+
+    *expected_result = MBEDTLS_ERR_SSL_DECODE_ERROR;
+
+    switch (tweak) {
+        case 1:
+            /* Failure when checking if the certificate request context length
+             * and certificate list length can be read
+             */
+            *end = buf + 3;
+            set_chk_buf_ptr_args(args, buf, *end, 4);
+            break;
+
+        case 2:
+            /* Invalid certificate request context length.
+             */
+            *p_certificate_request_context_len =
+                certificate_request_context_len + 1;
+            reset_chk_buf_ptr_args(args);
+            break;
+
+        case 3:
+            /* Failure when checking if certificate_list data can be read. */
+            MBEDTLS_PUT_UINT24_BE(certificate_list_len + 1,
+                                  p_certificate_list_len, 0);
+            set_chk_buf_ptr_args(args, certificate_list, *end,
+                                 certificate_list_len + 1);
+            break;
+
+        case 4:
+            /* Failure when checking if the cert_data length can be read. */
+            MBEDTLS_PUT_UINT24_BE(2, p_certificate_list_len, 0);
+            set_chk_buf_ptr_args(args, p_cert_data_len, certificate_list + 2, 3);
+            break;
+
+        case 5:
+            /* Failure when checking if cert_data data can be read. */
+            MBEDTLS_PUT_UINT24_BE(certificate_list_len - 3 + 1,
+                                  p_cert_data_len, 0);
+            set_chk_buf_ptr_args(args, cert_data,
+                                 certificate_list + certificate_list_len,
+                                 certificate_list_len - 3 + 1);
+            break;
+
+        case 6:
+            /* Failure when checking if the extensions length can be read. */
+            MBEDTLS_PUT_UINT24_BE(certificate_list_len - extensions_len - 1,
+                                  p_certificate_list_len, 0);
+            set_chk_buf_ptr_args(
+                args, p_extensions_len,
+                certificate_list + certificate_list_len - extensions_len - 1, 2);
+            break;
+
+        case 7:
+            /* Failure when checking if extensions data can be read. */
+            MBEDTLS_PUT_UINT16_BE(extensions_len + 1, p_extensions_len, 0);
+
+            set_chk_buf_ptr_args(
+                args, extensions,
+                certificate_list + certificate_list_len, extensions_len + 1);
+            break;
+
+        default:
+            return -1;
+    }
+
+    return 0;
+}
+#endif /* MBEDTLS_TEST_HOOKS */