Mercurial > dropbear
changeset 906:4696755c4cac
A few fixes for cases where compression increases payload sizes, and
be more precise about maximum channel sizes
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Sat, 22 Feb 2014 18:02:09 +0800 |
| parents | f98618496f82 |
| children | 4a74c58e11fc |
| files | common-channel.c packet.c |
| diffstat | 2 files changed, 19 insertions(+), 13 deletions(-) [+] |
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--- a/common-channel.c Wed Feb 19 22:18:11 2014 +0800 +++ b/common-channel.c Sat Feb 22 18:02:09 2014 +0800 @@ -59,6 +59,13 @@ #define ERRFD_IS_READ(channel) ((channel)->extrabuf == NULL) #define ERRFD_IS_WRITE(channel) (!ERRFD_IS_READ(channel)) +/* allow space for: + * 1 byte byte SSH_MSG_CHANNEL_DATA + * 4 bytes uint32 recipient channel + * 4 bytes string data + */ +#define RECV_MAX_CHANNEL_DATA_LEN (RECV_MAX_PAYLOAD_LEN-(1+4+4)) + /* Initialise all the channels */ void chaninitialise(const struct ChanType *chantypes[]) { @@ -165,7 +172,7 @@ newchan->extrabuf = NULL; /* The user code can set it up */ newchan->recvdonelen = 0; - newchan->recvmaxpacket = RECV_MAX_PAYLOAD_LEN; + newchan->recvmaxpacket = RECV_MAX_CHANNEL_DATA_LEN; ses.channels[i] = newchan; ses.chancount++; @@ -1028,7 +1035,7 @@ buf_putstring(ses.writepayload, type->name, strlen(type->name)); buf_putint(ses.writepayload, chan->index); buf_putint(ses.writepayload, opts.recv_window); - buf_putint(ses.writepayload, RECV_MAX_PAYLOAD_LEN); + buf_putint(ses.writepayload, RECV_MAX_CHANNEL_DATA_LEN); TRACE(("leave send_msg_channel_open_init()")) return DROPBEAR_SUCCESS;
--- a/packet.c Wed Feb 19 22:18:11 2014 +0800 +++ b/packet.c Sat Feb 22 18:02:09 2014 +0800 @@ -41,7 +41,11 @@ 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 @@ /* 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 @@ 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 @@ + 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 @@ #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 @@ /* 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"))