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tls: refactoring MakeTlsMasterSecret to reduce stack usage:

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--- variable seed moved to the heap (up to 64 bytes saved)
This commit is contained in:
Moisés Guimarães
2014-08-02 17:41:04 -03:00
parent c74440b27e
commit 04dd56df79
1 changed files with 23 additions and 8 deletions
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31
src/tls.c
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@ -452,29 +452,44 @@ int DeriveTlsKeys(CYASSL* ssl)
int MakeTlsMasterSecret(CYASSL* ssl) int MakeTlsMasterSecret(CYASSL* ssl)
{ {
int ret; int ret;
#ifdef CYASSL_SMALL_STACK
byte* seed;
#else
byte seed[SEED_LEN]; byte seed[SEED_LEN];
#endif
XMEMCPY(seed, ssl->arrays->clientRandom, RAN_LEN);
XMEMCPY(&seed[RAN_LEN], ssl->arrays->serverRandom, RAN_LEN); #ifdef CYASSL_SMALL_STACK
seed = (byte*)XMALLOC(SEED_LEN, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (seed == NULL)
return MEMORY_E;
#endif
XMEMCPY(seed, ssl->arrays->clientRandom, RAN_LEN);
XMEMCPY(seed + RAN_LEN, ssl->arrays->serverRandom, RAN_LEN);
ret = PRF(ssl->arrays->masterSecret, SECRET_LEN, ret = PRF(ssl->arrays->masterSecret, SECRET_LEN,
ssl->arrays->preMasterSecret, ssl->arrays->preMasterSz, ssl->arrays->preMasterSecret, ssl->arrays->preMasterSz,
master_label, MASTER_LABEL_SZ, master_label, MASTER_LABEL_SZ,
seed, SEED_LEN, IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm); seed, SEED_LEN, IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
if (ret != 0)
return ret;
#ifdef SHOW_SECRETS if (ret == 0) {
{ #ifdef SHOW_SECRETS
int i; int i;
printf("master secret: "); printf("master secret: ");
for (i = 0; i < SECRET_LEN; i++) for (i = 0; i < SECRET_LEN; i++)
printf("%02x", ssl->arrays->masterSecret[i]); printf("%02x", ssl->arrays->masterSecret[i]);
printf("\n"); printf("\n");
#endif
ret = DeriveTlsKeys(ssl);
} }
#ifdef CYASSL_SMALL_STACK
XFREE(seed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif #endif
return DeriveTlsKeys(ssl); return ret;
} }