/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
/**
* \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 'abstract 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 (SIZE_MAX)
/** \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 (SIZE_MAX)
#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 */
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