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A few fixes for cases where compression increases payload sizes, and

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be more precise about maximum channel sizes
This commit is contained in:
Matt Johnston
2014-02-22 18:02:09 +08:00
parent fb3c718963
commit bb7934bf04
2 changed files with 19 additions and 13 deletions
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21
packet.c
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@@ -41,7 +41,11 @@ static void make_mac(unsigned int seqno, const struct key_context_directional *
unsigned char *output_mac);
static int checkmac();
#define ZLIB_COMPRESS_INCR 100
/* For exact details see http://www.zlib.net/zlib_tech.html
* 5 bytes per 16kB block, plus 6 bytes for the stream.
* We might allocate 5 unnecessary bytes here if it's an
* exact multiple. */
#define ZLIB_COMPRESS_EXPANSION (((RECV_MAX_PAYLOAD_LEN/16384)+1)*5 + 6)
#define ZLIB_DECOMPRESS_INCR 1024
#ifndef DISABLE_ZLIB
static buffer* buf_decompress(buffer* buf, unsigned int len);
@@ -333,7 +337,7 @@ void decrypt_packet() {
/* payload length */
/* - 4 - 1 is for LEN and PADLEN values */
len = ses.readbuf->len - padlen - 4 - 1 - macsize;
if ((len > RECV_MAX_PAYLOAD_LEN) || (len < 1)) {
if ((len > RECV_MAX_PAYLOAD_LEN+ZLIB_COMPRESS_EXPANSION) || (len < 1)) {
dropbear_exit("Bad packet size %d", len);
}
@@ -422,6 +426,8 @@ static buffer* buf_decompress(buffer* buf, unsigned int len) {
if (zstream->avail_out == 0) {
int new_size = 0;
if (ret->size >= RECV_MAX_PAYLOAD_LEN) {
/* Already been increased as large as it can go,
* yet didn't finish up the decompression */
dropbear_exit("bad packet, oversized decompressed");
}
new_size = MIN(RECV_MAX_PAYLOAD_LEN, ret->size + ZLIB_DECOMPRESS_INCR);
@@ -526,7 +532,7 @@ void encrypt_packet() {
+ mac_size
#ifndef DISABLE_ZLIB
/* some extra in case 'compression' makes it larger */
+ ZLIB_COMPRESS_INCR
+ ZLIB_COMPRESS_EXPANSION
#endif
/* and an extra cleartext (stripped before transmission) byte for the
* packet type */
@@ -539,14 +545,7 @@ void encrypt_packet() {
#ifndef DISABLE_ZLIB
/* compression */
if (is_compress_trans()) {
int compress_delta;
buf_compress(writebuf, ses.writepayload, ses.writepayload->len);
compress_delta = (writebuf->len - PACKET_PAYLOAD_OFF) - ses.writepayload->len;
/* Handle the case where 'compress' increased the size. */
if (compress_delta > ZLIB_COMPRESS_INCR) {
buf_resize(writebuf, writebuf->size + compress_delta);
}
} else
#endif
{
@@ -694,7 +693,7 @@ static void buf_compress(buffer * dest, buffer * src, unsigned int len) {
/* the buffer has been filled, we must extend. This only happens in
* unusual circumstances where the data grows in size after deflate(),
* but it is possible */
buf_resize(dest, dest->size + ZLIB_COMPRESS_INCR);
buf_resize(dest, dest->size + ZLIB_COMPRESS_EXPANSION);
}
TRACE2(("leave buf_compress"))