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Make libssh2_packet_read() use a static buffer to avoid unnecessary

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alloc and free calls.

Since the cipher and mac layers aren't runtime extensible (yet)
and we know neither of these works in sizes greater than 32,
we can safely set aside a 64 byte block of data on the stack
for crypting and hashing.

This will make a big difference during quasi-non-blocking reads
where libssh2_packet_read() is polled repeatedly.
This commit is contained in:
Sara Golemon
2004-12-23 00:42:20 +00:00
parent d4efdee802
commit f11c657a10
2 changed files with 6 additions and 16 deletions
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20
src/packet.c
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@@ -317,7 +317,10 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
fcntl(session->socket_fd, F_SETFL, O_NONBLOCK);
if (session->newkeys) {
unsigned char *block, *payload, *s, tmp[6];
/* Temporary Buffer
* The largest blocksize (currently) is 32, the largest MAC (currently) is 20
*/
unsigned char block[2 * 32], *payload, *s, tmp[6];
long read_len;
unsigned long blocksize = session->remote.crypt->blocksize;
unsigned long packet_len, payload_len;
@@ -327,9 +330,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
/* Safely ignored in CUSTOM cipher mode */
EVP_CIPHER_CTX *ctx = (EVP_CIPHER_CTX *)session->remote.crypt_abstract;
/* Temporary Buffer */
block = LIBSSH2_ALLOC(session, 2 * (blocksize > session->remote.mac->mac_len ? blocksize : session->remote.mac->mac_len));
/* Note: If we add any cipher with a blocksize less than 6 we'll need to get more creative with this
* For now, all blocksize sizes are 8+
*/
@@ -338,13 +338,11 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
} else {
read_len = read(session->socket_fd, block, 1);
if (read_len <= 0) {
LIBSSH2_FREE(session, block);
return 0;
}
read_len += libssh2_blocking_read(session, block + read_len, blocksize - read_len);
}
if (read_len < blocksize) {
LIBSSH2_FREE(session, block);
return (session->socket_state == LIBSSH2_SOCKET_DISCONNECTED) ? 0 : -1;
}
@@ -354,7 +352,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
} else {
if (session->remote.crypt->crypt(session, block, &session->remote.crypt_abstract)) {
libssh2_error(session, LIBSSH2_ERROR_DECRYPT, "Error decrypting packet preamble", 0);
LIBSSH2_FREE(session, block);
return -1;
}
}
@@ -368,7 +365,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
if ((payload_len > LIBSSH2_PACKET_MAXPAYLOAD) ||
((packet_len + 4) % blocksize)) {
/* If something goes horribly wrong during the decryption phase, just bailout and die gracefully */
LIBSSH2_FREE(session, block);
session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
libssh2_error(session, LIBSSH2_ERROR_PROTO, "Fatal protocol error, invalid payload size", 0);
return -1;
@@ -381,7 +377,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
while ((s - payload) < payload_len) {
read_len = libssh2_blocking_read(session, block, blocksize);
if (read_len < blocksize) {
LIBSSH2_FREE(session, block);
LIBSSH2_FREE(session, payload);
return -1;
}
@@ -391,7 +386,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
} else {
if (session->remote.crypt->crypt(session, block, &session->remote.crypt_abstract)) {
libssh2_error(session, LIBSSH2_ERROR_DECRYPT, "Error decrypting packet preamble", 0);
LIBSSH2_FREE(session, block);
LIBSSH2_FREE(session, payload);
return -1;
}
@@ -403,7 +397,6 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
read_len = libssh2_blocking_read(session, block, session->remote.mac->mac_len);
if (read_len < session->remote.mac->mac_len) {
LIBSSH2_FREE(session, block);
LIBSSH2_FREE(session, payload);
return -1;
}
@@ -412,13 +405,9 @@ int libssh2_packet_read(LIBSSH2_SESSION *session, int should_block)
session->remote.mac->hash(session, block + session->remote.mac->mac_len, session->remote.seqno, tmp, 5, payload, payload_len, &session->remote.mac_abstract);
macstate = (strncmp(block, block + session->remote.mac->mac_len, session->remote.mac->mac_len) == 0) ? LIBSSH2_MAC_CONFIRMED : LIBSSH2_MAC_INVALID;
/* SMG */
if (macstate == LIBSSH2_MAC_INVALID) libssh2_error(session, -255, "EEEK an error!", 0);
session->remote.seqno++;
LIBSSH2_FREE(session, block);
/* Ignore padding */
payload_len -= padding_len;
@@ -451,7 +440,6 @@ if (macstate == LIBSSH2_MAC_INVALID) libssh2_error(session, -255, "EEEK an error
payload = LIBSSH2_ALLOC(session, data_len);
if (!payload) {
libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for copy of uncompressed data", 0);
LIBSSH2_FREE(session, block);
return -1;
}
memcpy(payload, data, data_len);