platform_util.h File Reference

Common and shared functions used by multiple modules in the Mbed TLS library. More...

#include "config.h"
#include <stddef.h>
#include "platform_time.h"
#include <time.h>

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Macros
#define	MBEDTLS_INTERNAL_VALIDATE_RET(cond, ret)   do { } while( 0 )
#define	MBEDTLS_INTERNAL_VALIDATE(cond)   do { } while( 0 )
#define	MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL)   VAL
#define	MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL)   VAL

Functions
void	mbedtls_platform_zeroize (void *buf, size_t len)
	Securely zeroize a buffer. More...
struct tm *	mbedtls_platform_gmtime_r (const mbedtls_time_t *tt, struct tm *tm_buf)
	Platform-specific implementation of gmtime_r() More...

Detailed Description

Common and shared functions used by multiple modules in the Mbed TLS library.

Definition in file platform_util.h.

Macro Definition Documentation

#define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT

(

VAL

)

VAL

Definition at line 122 of file platform_util.h.

#define MBEDTLS_DEPRECATED_STRING_CONSTANT

(

VAL

)

VAL

Definition at line 121 of file platform_util.h.

#define MBEDTLS_INTERNAL_VALIDATE

(

cond

)

do { } while( 0 )

Definition at line 101 of file platform_util.h.

#define MBEDTLS_INTERNAL_VALIDATE_RET	(		cond,
			ret
	)		do { } while( 0 )

Definition at line 100 of file platform_util.h.

Referenced by mbedtls_cipher_get_block_size(), mbedtls_cipher_get_cipher_mode(), mbedtls_cipher_get_iv_size(), mbedtls_cipher_get_key_bitlen(), mbedtls_cipher_get_name(), mbedtls_cipher_get_operation(), and mbedtls_cipher_get_type().

Function Documentation

struct tm* mbedtls_platform_gmtime_r	(	const mbedtls_time_t *	tt,
		struct tm *	tm_buf
	)

Platform-specific implementation of gmtime_r()

The function is a thread-safe abstraction that behaves similarly to the gmtime_r() function from Unix/POSIX.

Mbed TLS will try to identify the underlying platform and make use of an appropriate underlying implementation (e.g. gmtime_r() for POSIX and gmtime_s() for Windows). If this is not possible, then gmtime() will be used. In this case, calls from the library to gmtime() will be guarded by the mutex mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is enabled. It is recommended that calls from outside the library are also guarded by this mutex.

If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will unconditionally use the alternative implementation for mbedtls_platform_gmtime_r() supplied by the user at compile time.

Parameters

tt	Pointer to an object containing time (in seconds) since the epoch to be converted
tm_buf	Pointer to an object where the results will be stored

Returns

Pointer to an object of type struct tm on success, otherwise NULL

void mbedtls_platform_zeroize	(	void *	buf,
		size_t	len
	)

Securely zeroize a buffer.

The function is meant to wipe the data contained in a buffer so that it can no longer be recovered even if the program memory is later compromised. Call this function on sensitive data stored on the stack before returning from a function, and on sensitive data stored on the heap before freeing the heap object.

It is extremely difficult to guarantee that calls to mbedtls_platform_zeroize() are not removed by aggressive compiler optimizations in a portable way. For this reason, Mbed TLS provides the configuration option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure mbedtls_platform_zeroize() to use a suitable implementation for their platform and needs

Parameters

buf	Buffer to be zeroized
len	Length of the buffer in bytes