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| author | Hans Nilsson <[email protected]> | 2015-08-20 14:40:39 +0200 |
|---|---|---|
| committer | Hans Nilsson <[email protected]> | 2015-08-25 15:40:13 +0200 |
| commit | 2564e317e34fe7f928bf6e234998b295848a5c91 (patch) | |
| tree | 84238b065c7e993633b6383561d3ffd602d49242 /lib/ssh/src/ssh_transport.erl | |
| parent | a93087eafd98bf60b9611c807d0074d304e93383 (diff) | |
| download | otp-2564e317e34fe7f928bf6e234998b295848a5c91.tar.gz otp-2564e317e34fe7f928bf6e234998b295848a5c91.tar.bz2 otp-2564e317e34fe7f928bf6e234998b295848a5c91.zip | |
ssh: add extra random length padding in packets
A new experimental option 'max_random_length_padding', not documented so it might change...
Diffstat (limited to 'lib/ssh/src/ssh_transport.erl')
| -rw-r--r-- | lib/ssh/src/ssh_transport.erl | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl index 38a0b7ec7c..9ed6c85ff7 100644 --- a/lib/ssh/src/ssh_transport.erl +++ b/lib/ssh/src/ssh_transport.erl @@ -745,13 +745,20 @@ ssh_packet(Msg, Ssh) -> pack(Data0, #ssh{encrypt_block_size = BlockSize, send_sequence = SeqNum, send_mac = MacAlg, - send_mac_key = MacKey} + send_mac_key = MacKey, + random_length_padding = RandomLengthPadding} = Ssh0) when is_binary(Data0) -> {Ssh1, Data} = compress(Ssh0, Data0), PL = (BlockSize - ((4 + 1 + size(Data)) rem BlockSize)) rem BlockSize, - PaddingLen = if PL < 4 -> PL + BlockSize; - true -> PL - end, + MinPaddingLen = if PL < 4 -> PL + BlockSize; + true -> PL + end, + PadBlockSize = max(BlockSize,4), + MaxExtraBlocks = (max(RandomLengthPadding,MinPaddingLen) - MinPaddingLen) div PadBlockSize, + ExtraPaddingLen = try crypto:rand_uniform(0,MaxExtraBlocks)*PadBlockSize + catch _:_ -> 0 + end, + PaddingLen = MinPaddingLen + ExtraPaddingLen, Padding = ssh_bits:random(PaddingLen), PacketLen = 1 + PaddingLen + size(Data), PacketData = <<?UINT32(PacketLen),?BYTE(PaddingLen), |