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tls: refactoring DeriveTlsKeys to reduce stack usage:

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--- variable seed moved to the heap (up to 64 bytes saved)
--- variable key_data moved to the heap (up to 224 bytes saved)
This commit is contained in:
Moisés Guimarães 2014-08-02 17:25:39 -03:00
parent 0283a917e8
commit c74440b27e
1 changed files with 28 additions and 5 deletions
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33
src/tls.c
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@ -410,19 +410,42 @@ int DeriveTlsKeys(CYASSL* ssl)
int length = 2 * ssl->specs.hash_size +
2 * ssl->specs.key_size +
2 * ssl->specs.iv_size;
#ifdef CYASSL_SMALL_STACK
byte* seed;
byte* key_data;
#else
byte seed[SEED_LEN];
byte key_data[MAX_PRF_DIG];
#endif
XMEMCPY(seed, ssl->arrays->serverRandom, RAN_LEN);
XMEMCPY(&seed[RAN_LEN], ssl->arrays->clientRandom, RAN_LEN);
#ifdef CYASSL_SMALL_STACK
seed = (byte*)XMALLOC(SEED_LEN, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (seed == NULL)
return MEMORY_E;
key_data = (byte*)XMALLOC(MAX_PRF_DIG, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (key_data == NULL) {
XFREE(seed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
XMEMCPY(seed, ssl->arrays->serverRandom, RAN_LEN);
XMEMCPY(seed + RAN_LEN, ssl->arrays->clientRandom, RAN_LEN);
ret = PRF(key_data, length, ssl->arrays->masterSecret, SECRET_LEN,
key_label, KEY_LABEL_SZ, seed, SEED_LEN, IsAtLeastTLSv1_2(ssl),
ssl->specs.mac_algorithm);
if (ret != 0)
return ret;
return StoreKeys(ssl, key_data);
if (ret == 0)
ret = StoreKeys(ssl, key_data);
#ifdef CYASSL_SMALL_STACK
XFREE(seed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(key_data, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}