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Avoid in-out length parameter in bignum

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Manuel Pégourié-Gonnard 2015-06-02 15:41:48 +01:00
parent 9693668c23
commit f79b425226
3 changed files with 20 additions and 19 deletions
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14
include/mbedtls/bignum.h
View file

@ -324,17 +324,19 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s );
*
* \param X Source MPI
* \param radix Output numeric base
* \param s String buffer
* \param slen String buffer size
* \param buf Buffer to write the string to
* \param buflen Length of buf
* \param olen Length of the string written, including final NUL byte
*
* \return 0 if successful, or a MBEDTLS_ERR_MPI_XXX error code.
* *slen is always updated to reflect the amount
* *olen is always updated to reflect the amount
* of data that has (or would have) been written.
*
* \note Call this function with *slen = 0 to obtain the
* minimum required buffer size in *slen.
* \note Call this function with buflen = 0 to obtain the
* minimum required buffer size in *olen.
*/
int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix, char *s, size_t *slen );
int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix,
char *buf, size_t buflen, size_t *olen );
#if defined(MBEDTLS_FS_IO)
/**

17
library/bignum.c
View file

@ -490,7 +490,8 @@ cleanup:
/*
* Export into an ASCII string
*/
int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix, char *s, size_t *slen )
int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix,
char *buf, size_t buflen, size_t *olen )
{
int ret = 0;
size_t n;
@ -505,13 +506,13 @@ int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix, char *s, size_t *
if( radix >= 16 ) n >>= 1;
n += 3;
if( *slen < n )
if( buflen < n )
{
*slen = n;
*olen = n;
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
}
p = s;
p = buf;
mbedtls_mpi_init( &T );
if( X->s == -1 )
@ -548,7 +549,7 @@ int mbedtls_mpi_write_string( const mbedtls_mpi *X, int radix, char *s, size_t *
}
*p++ = '\0';
*slen = p - s;
*olen = p - buf;
cleanup:
@ -604,11 +605,9 @@ int mbedtls_mpi_write_file( const char *p, const mbedtls_mpi *X, int radix, FILE
*/
char s[ MBEDTLS_MPI_RW_BUFFER_SIZE ];
n = sizeof( s );
memset( s, 0, n );
n -= 2;
memset( s, 0, sizeof( s ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_string( X, radix, s, (size_t *) &n ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_string( X, radix, s, sizeof( s ) - 2, &n ) );
if( p == NULL ) p = "";

8
tests/suites/test_suite_mpi.function
View file

@ -33,14 +33,14 @@ void mpi_read_write_string( int radix_X, char *input_X, int radix_A,
{
mbedtls_mpi X;
char str[1000];
size_t len = output_size;
size_t len;
mbedtls_mpi_init( &X );
TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == result_read );
if( result_read == 0 )
{
TEST_ASSERT( mbedtls_mpi_write_string( &X, radix_A, str, &len ) == result_write );
TEST_ASSERT( mbedtls_mpi_write_string( &X, radix_A, str, output_size, &len ) == result_write );
if( result_write == 0 )
{
TEST_ASSERT( strcasecmp( str, input_A ) == 0 );
@ -58,7 +58,7 @@ void mbedtls_mpi_read_binary( char *input_X, int radix_A, char *input_A )
mbedtls_mpi X;
unsigned char str[1000];
unsigned char buf[1000];
size_t len = 1000;
size_t len;
size_t input_len;
mbedtls_mpi_init( &X );
@ -66,7 +66,7 @@ void mbedtls_mpi_read_binary( char *input_X, int radix_A, char *input_A )
input_len = unhexify( buf, input_X );
TEST_ASSERT( mbedtls_mpi_read_binary( &X, buf, input_len ) == 0 );
TEST_ASSERT( mbedtls_mpi_write_string( &X, radix_A, (char *) str, &len ) == 0 );
TEST_ASSERT( mbedtls_mpi_write_string( &X, radix_A, (char *) str, sizeof( str ), &len ) == 0 );
TEST_ASSERT( strcmp( (char *) str, input_A ) == 0 );
exit: