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asn: refactoring GetCertHeader to reduce stack usage: ~ sizeof(mp_int) bytes moved to the heap. 

--- variable mpi moved to the heap (~ sizeof(mp_int) bytes saved)
This commit is contained in:
Moisés Guimarães 2014-06-25 15:10:36 -03:00
parent adf5ba96e6
commit 40ef0c8daa
1 changed files with 28 additions and 8 deletions
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36
ctaocrypt/src/asn.c
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@ -1433,9 +1433,14 @@ void FreeDecodedCert(DecodedCert* cert)
static int GetCertHeader(DecodedCert* cert)
{
int ret = 0, len;
byte serialTmp[EXTERNAL_SERIAL_SIZE];
mp_int mpi;
int ret = 0, len;
byte serialTmp[EXTERNAL_SERIAL_SIZE];
#if defined(CYASSL_SMALL_STACK) && defined(USE_FAST_MATH)
mp_int* mpi = NULL;
#else
mp_int stack_mpi;
mp_int* mpi = &stack_mpi;
#endif
if (GetSequence(cert->source, &cert->srcIdx, &len, cert->maxIdx) < 0)
return ASN_PARSE_E;
@ -1449,17 +1454,32 @@ static int GetCertHeader(DecodedCert* cert)
if (GetExplicitVersion(cert->source, &cert->srcIdx, &cert->version) < 0)
return ASN_PARSE_E;
if (GetInt(&mpi, cert->source, &cert->srcIdx, cert->maxIdx) < 0)
return ASN_PARSE_E;
#if defined(CYASSL_SMALL_STACK) && defined(USE_FAST_MATH)
mpi = (mp_int*)XMALLOC(sizeof(mp_int), NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (mpi == NULL)
return MEMORY_E;
#endif
len = mp_unsigned_bin_size(&mpi);
if (GetInt(mpi, cert->source, &cert->srcIdx, cert->maxIdx) < 0) {
#if defined(CYASSL_SMALL_STACK) && defined(USE_FAST_MATH)
XFREE(mpi, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ASN_PARSE_E;
}
len = mp_unsigned_bin_size(mpi);
if (len < (int)sizeof(serialTmp)) {
if ( (ret = mp_to_unsigned_bin(&mpi, serialTmp)) == MP_OKAY) {
if ( (ret = mp_to_unsigned_bin(mpi, serialTmp)) == MP_OKAY) {
XMEMCPY(cert->serial, serialTmp, len);
cert->serialSz = len;
}
}
mp_clear(&mpi);
mp_clear(mpi);
#if defined(CYASSL_SMALL_STACK) && defined(USE_FAST_MATH)
XFREE(mpi, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}