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+/*
+ * Copyright The Mbed TLS Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ *
+ * This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+/**
+ * \file mps_common.h
+ *
+ * \brief Common functions and macros used by MPS
+ */
+
+#ifndef MBEDTLS_MPS_COMMON_H
+#define MBEDTLS_MPS_COMMON_H
+
+#include "mps_error.h"
+
+#include <stdio.h>
+
+/**
+ * \name SECTION: MPS Configuration
+ *
+ * \{
+ */
+
+/*! This flag controls whether the MPS-internal components
+ * (reader, writer, Layer 1-3) perform validation of the
+ * expected abstract state at the entry of API calls.
+ *
+ * Context: All MPS API functions impose assumptions/preconditions on the
+ * context on which they operate. For example, every structure has a notion of
+ * state integrity which is established by `xxx_init()` and preserved by any
+ * calls to the MPS API which satisfy their preconditions and either succeed,
+ * or fail with an error code which is explicitly documented to not corrupt
+ * structure integrity (such as WANT_READ and WANT_WRITE);
+ * apart from `xxx_init()` any function assumes state integrity as a
+ * precondition (but usually more). If any of the preconditions is violated,
+ * the function's behavior is entirely undefined.
+ * In addition to state integrity, all MPS structures have a more refined
+ * notion of abstract state that the API operates on. For example, all layers
+ * have a notion of 'abtract read state' which indicates if incoming data has
+ * been passed to the user, e.g. through mps_l2_read_start() for Layer 2
+ * or mps_l3_read() in Layer 3. After such a call, it doesn't make sense to
+ * call these reading functions again until the incoming data has been
+ * explicitly 'consumed', e.g. through mps_l2_read_consume() for Layer 2 or
+ * mps_l3_read_consume() on Layer 3. However, even if it doesn't make sense,
+ * it's a design choice whether the API should fail gracefully on such
+ * non-sensical calls or not, and that's what this option is about:
+ *
+ * This option determines whether the expected abstract state
+ * is part of the API preconditions or not: If the option is set,
+ * then the abstract state is not part of the precondition and is
+ * thus required to be validated by the implementation. If an unexpected
+ * abstract state is encountered, the implementation must fail gracefully
+ * with error #MBEDTLS_ERR_MPS_OPERATION_UNEXPECTED.
+ * Conversely, if this option is not set, then the expected abstract state
+ * is included in the preconditions of the respective API calls, and
+ * an implementation's behaviour is undefined if the abstract state is
+ * not as expected.
+ *
+ * For example: Enabling this makes mps_l2_read_done() fail if
+ * no incoming record is currently open; disabling this would
+ * lead to undefined behavior in this case.
+ *
+ * Comment this to remove state validation.
+ */
+#define MBEDTLS_MPS_STATE_VALIDATION
+
+/*! This flag enables/disables assertions on the internal state of MPS.
+ *
+ * Assertions are sanity checks that should never trigger when MPS
+ * is used within the bounds of its API and preconditions.
+ *
+ * Enabling this increases security by limiting the scope of
+ * potential bugs, but comes at the cost of increased code size.
+ *
+ * Note: So far, there is no guiding principle as to what
+ * expected conditions merit an assertion, and which don't.
+ *
+ * Comment this to disable assertions.
+ */
+#define MBEDTLS_MPS_ENABLE_ASSERTIONS
+
+/*! This flag controls whether tracing for MPS should be enabled. */
+//#define MBEDTLS_MPS_ENABLE_TRACE
+
+#if defined(MBEDTLS_MPS_STATE_VALIDATION)
+
+#define MBEDTLS_MPS_STATE_VALIDATE_RAW( cond, string ) \
+ do \
+ { \
+ if( !(cond) ) \
+ { \
+ MBEDTLS_MPS_TRACE( MBEDTLS_MPS_TRACE_TYPE_ERROR, string ); \
+ MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_OPERATION_UNEXPECTED ); \
+ } \
+ } while( 0 )
+
+#else /* MBEDTLS_MPS_STATE_VALIDATION */
+
+#define MBEDTLS_MPS_STATE_VALIDATE_RAW( cond, string ) \
+ do \
+ { \
+ ( cond ); \
+ } while( 0 )
+
+#endif /* MBEDTLS_MPS_STATE_VALIDATION */
+
+#if defined(MBEDTLS_MPS_ENABLE_ASSERTIONS)
+
+#define MBEDTLS_MPS_ASSERT_RAW( cond, string ) \
+ do \
+ { \
+ if( !(cond) ) \
+ { \
+ MBEDTLS_MPS_TRACE( MBEDTLS_MPS_TRACE_TYPE_ERROR, string ); \
+ MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_INTERNAL_ERROR ); \
+ } \
+ } while( 0 )
+
+#else /* MBEDTLS_MPS_ENABLE_ASSERTIONS */
+
+#define MBEDTLS_MPS_ASSERT_RAW( cond, string ) do {} while( 0 )
+
+#endif /* MBEDTLS_MPS_ENABLE_ASSERTIONS */
+
+
+/* \} name SECTION: MPS Configuration */
+
+/**
+ * \name SECTION: Common types
+ *
+ * Various common types used throughout MPS.
+ * \{
+ */
+
+/** \brief The type of buffer sizes and offsets used in MPS structures.
+ *
+ * This is an unsigned integer type that should be large enough to
+ * hold the length of any buffer or message processed by MPS.
+ *
+ * The reason to pick a value as small as possible here is
+ * to reduce the size of MPS structures.
+ *
+ * \warning Care has to be taken when using a narrower type
+ * than ::mbedtls_mps_size_t here because of
+ * potential truncation during conversion.
+ *
+ * \warning Handshake messages in TLS may be up to 2^24 ~ 16Mb in size.
+ * If mbedtls_mps_[opt_]stored_size_t is smaller than that, the
+ * maximum handshake message is restricted accordingly.
+ *
+ * For now, we use the default type of size_t throughout, and the use of
+ * smaller types or different types for ::mbedtls_mps_size_t and
+ * ::mbedtls_mps_stored_size_t is not yet supported.
+ *
+ */
+typedef size_t mbedtls_mps_stored_size_t;
+#define MBEDTLS_MPS_STORED_SIZE_MAX ( (mbedtls_mps_stored_size_t) -1 )
+
+/** \brief The type of buffer sizes and offsets used in the MPS API
+ * and implementation.
+ *
+ * This must be at least as wide as ::mbedtls_stored_size_t but
+ * may be chosen to be strictly larger if more suitable for the
+ * target architecture.
+ *
+ * For example, in a test build for ARM Thumb, using uint_fast16_t
+ * instead of uint16_t reduced the code size from 1060 Byte to 962 Byte,
+ * so almost 10%.
+ */
+typedef size_t mbedtls_mps_size_t;
+#define MBEDTLS_MPS_SIZE_MAX ( (mbedtls_mps_size_t) -1 )
+
+#if MBEDTLS_MPS_STORED_SIZE_MAX > MBEDTLS_MPS_SIZE_MAX
+#error "Misconfiguration of mbedtls_mps_size_t and mbedtls_mps_stored_size_t."
+#endif
+
+/* \} SECTION: Common types */
+
+
+#endif /* MBEDTLS_MPS_COMMON_H */