%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2005-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
%%% Description : SSH 1/2 pdu elements encode/decode
-module(ssh_bits).
-include("ssh.hrl").
-export([encode/2, decode/2]).
%%-export([decode/1, decode/2, decode/3]).
-export([mpint/1, bignum/1, string/1, name_list/1]).
%%-export([b64_encode/1, b64_decode/1]).
%%-export([install_messages/1, uninstall_messages/1]).
%% integer utils
-export([isize/1]).
-export([random/1]).
%%-export([xor_bits/2, fill_bits/2]).
-export([i2bin/2, bin2i/1]).
%%-import(lists, [foreach/2, reverse/1]).
-define(name_list(X),
(fun(B) -> ?binary(B) end)(list_to_binary(name_concat(X)))).
name_concat([Name]) when is_atom(Name) -> atom_to_list(Name);
name_concat([Name]) when is_list(Name) -> Name;
name_concat([Name|Ns]) ->
if is_atom(Name) ->
[atom_to_list(Name),"," | name_concat(Ns)];
is_list(Name) ->
[Name,"," | name_concat(Ns)]
end;
name_concat([]) -> [].
name_list(Ns) ->
?name_list(Ns).
string(Str) ->
?string(Str).
%% MP representaion (SSH2)
mpint(X) when X < 0 ->
if X == -1 ->
<<0,0,0,1,16#ff>>;
true ->
mpint_neg(X,0,[])
end;
mpint(X) ->
if X == 0 ->
<<0,0,0,0>>;
true ->
mpint_pos(X,0,[])
end.
mpint_neg(-1,I,Ds=[MSB|_]) ->
if MSB band 16#80 =/= 16#80 ->
<<?UINT32((I+1)), (list_to_binary([255|Ds]))/binary>>;
true ->
(<<?UINT32(I), (list_to_binary(Ds))/binary>>)
end;
mpint_neg(X,I,Ds) ->
mpint_neg(X bsr 8,I+1,[(X band 255)|Ds]).
mpint_pos(0,I,Ds=[MSB|_]) ->
if MSB band 16#80 == 16#80 ->
<<?UINT32((I+1)), (list_to_binary([0|Ds]))/binary>>;
true ->
(<<?UINT32(I), (list_to_binary(Ds))/binary>>)
end;
mpint_pos(X,I,Ds) ->
mpint_pos(X bsr 8,I+1,[(X band 255)|Ds]).
%% BIGNUM representation SSH1
bignum(X) ->
XSz = isize(X),
Pad = (8 - (XSz rem 8)) rem 8,
<<?UINT16(XSz),0:Pad/unsigned-integer,X:XSz/big-unsigned-integer>>.
%% install_messages(Codes) ->
%% foreach(fun({Name, Code, Ts}) ->
%% put({msg_name,Code}, {Name,Ts}),
%% put({msg_code,Name}, {Code,Ts})
%% end, Codes).
%% uninstall_messages(Codes) ->
%% foreach(fun({Name, Code, _Ts}) ->
%% erase({msg_name,Code}),
%% erase({msg_code,Name})
%% end, Codes).
%%
%% Encode a record, the type spec is expected to be
%% in process dictionary under the key {msg_code, RecodeName}
%%
%% encode(Record) ->
%% case get({msg_code, element(1, Record)}) of
%% undefined ->
%% {error, unimplemented};
%% {Code, Ts} ->
%% Data = enc(tl(tuple_to_list(Record)), Ts),
%% list_to_binary([Code, Data])
%% end.
encode(List, Types) ->
list_to_binary(enc(List, Types)).
%%
%% Encode record element
%%
enc(Xs, Ts) ->
enc(Xs, Ts, 0).
enc(Xs, [boolean|Ts], Offset) ->
X = hd(Xs),
[?boolean(X) | enc(tl(Xs), Ts, Offset+1)];
enc(Xs, [byte|Ts], Offset) ->
X = hd(Xs),
[?byte(X) | enc(tl(Xs), Ts,Offset+1)];
enc(Xs, [uint16|Ts], Offset) ->
X = hd(Xs),
[?uint16(X) | enc(tl(Xs), Ts,Offset+2)];
enc(Xs, [uint32 |Ts], Offset) ->
X = hd(Xs),
[?uint32(X) | enc(tl(Xs), Ts,Offset+4)];
enc(Xs, [uint64|Ts], Offset) ->
X = hd(Xs),
[?uint64(X) | enc(tl(Xs), Ts,Offset+8)];
enc(Xs, [mpint|Ts], Offset) ->
Y = mpint(hd(Xs)),
[Y | enc(tl(Xs), Ts,Offset+size(Y))];
enc(Xs, [bignum|Ts], Offset) ->
Y = bignum(hd(Xs)),
[Y | enc(tl(Xs),Ts,Offset+size(Y))];
enc(Xs, [string|Ts], Offset) ->
X0 = hd(Xs),
Y = ?string(X0),
[Y | enc(tl(Xs),Ts,Offset+size(Y))];
enc(Xs, [binary|Ts], Offset) ->
X0 = hd(Xs),
Y = ?binary(X0),
[Y | enc(tl(Xs), Ts,Offset+size(Y))];
enc(Xs, [name_list|Ts], Offset) ->
X0 = hd(Xs),
Y = ?name_list(X0),
[Y | enc(tl(Xs), Ts, Offset+size(Y))];
enc(Xs, [cookie|Ts], Offset) ->
[random(16) | enc(tl(Xs), Ts, Offset+16)];
enc(Xs, [{pad,N}|Ts], Offset) ->
K = (N - (Offset rem N)) rem N,
[fill_bits(K,0) | enc(Xs, Ts, Offset+K)];
enc(Xs, ['...'| []], _Offset) ->
X = hd(Xs),
if is_binary(X) ->
[X];
is_list(X) ->
[list_to_binary(X)];
X==undefined ->
[]
end;
enc([], [],_) ->
[].
%%
%% Decode a SSH record the type is encoded as the first byte
%% and the type spec MUST be installed in {msg_name, ID}
%%
%% decode(Binary = <<?BYTE(ID), _/binary>>) ->
%% case get({msg_name, ID}) of
%% undefined ->
%% {unknown, Binary};
%% {Name, Ts} ->
%% {_, Elems} = decode(Binary,1,Ts),
%% list_to_tuple([Name | Elems])
%% end.
%%
%% Decode a binary form offset 0
%%
decode(Binary, Types) when is_binary(Binary) andalso is_list(Types) ->
{_,Elems} = decode(Binary, 0, Types),
Elems.
%% %%
%% %% Decode a binary from byte offset Offset
%% %% return {UpdatedOffset, DecodedElements}
%% %%
decode(Binary, Offset, Types) ->
decode(Binary, Offset, Types, []).
decode(Binary, Offset, [Type|Ts], Acc) ->
case Type of
boolean ->
<<_:Offset/binary, ?BOOLEAN(X0), _/binary>> = Binary,
X = if X0 == 0 -> false; true -> true end,
decode(Binary, Offset+1, Ts, [X | Acc]);
byte ->
<<_:Offset/binary, ?BYTE(X), _/binary>> = Binary,
decode(Binary, Offset+1, Ts, [X | Acc]);
uint16 ->
<<_:Offset/binary, ?UINT16(X), _/binary>> = Binary,
decode(Binary, Offset+2, Ts, [X | Acc]);
uint32 ->
<<_:Offset/binary, ?UINT32(X), _/binary>> = Binary,
decode(Binary, Offset+4, Ts, [X | Acc]);
uint64 ->
<<_:Offset/binary, ?UINT64(X), _/binary>> = Binary,
decode(Binary, Offset+8, Ts, [X | Acc]);
mpint ->
<<_:Offset/binary, ?UINT32(L), X0:L/binary,_/binary>> = Binary,
Sz = L*8,
<<X:Sz/big-signed-integer>> = X0,
decode(Binary, Offset+4+L, Ts, [X | Acc]);
bignum ->
<<_:Offset/binary, ?UINT16(Bits),_/binary>> = Binary,
L = (Bits+7) div 8,
Pad = (8 - (Bits rem 8)) rem 8,
<<_:Offset/binary, _:16, _:Pad, X:Bits/big-unsigned-integer,
_/binary>> = Binary,
decode(Binary, Offset+2+L, Ts, [X | Acc]);
string ->
Size = size(Binary),
if Size < Offset + 4 ->
%% empty string at end
{Size, lists:reverse(["" | Acc])};
true ->
<<_:Offset/binary,?UINT32(L), X:L/binary,_/binary>> =
Binary,
decode(Binary, Offset+4+L, Ts, [binary_to_list(X) |
Acc])
end;
binary ->
<<_:Offset/binary,?UINT32(L), X:L/binary,_/binary>> = Binary,
decode(Binary, Offset+4+L, Ts, [X | Acc]);
name_list ->
<<_:Offset/binary,?UINT32(L), X:L/binary,_/binary>> = Binary,
List = string:tokens(binary_to_list(X), ","),
decode(Binary, Offset+4+L, Ts, [List | Acc]);
cookie ->
<<_:Offset/binary, X:16/binary, _/binary>> = Binary,
decode(Binary, Offset+16, Ts, [X | Acc]);
{pad,N} -> %% pad offset to a multiple of N
K = (N - (Offset rem N)) rem N,
decode(Binary, Offset+K, Ts, Acc);
'...' when Ts==[] ->
<<_:Offset/binary, X/binary>> = Binary,
{Offset+size(X), lists:reverse([X | Acc])}
end;
decode(_Binary, Offset, [], Acc) ->
{Offset, lists:reverse(Acc)}.
%% HACK WARNING :-)
-define(VERSION_MAGIC, 131).
-define(SMALL_INTEGER_EXT, $a).
-define(INTEGER_EXT, $b).
-define(SMALL_BIG_EXT, $n).
-define(LARGE_BIG_EXT, $o).
isize(N) when N > 0 ->
case term_to_binary(N) of
<<?VERSION_MAGIC, ?SMALL_INTEGER_EXT, X>> ->
isize_byte(X);
<<?VERSION_MAGIC, ?INTEGER_EXT, X3,X2,X1,X0>> ->
isize_bytes([X3,X2,X1,X0]);
<<?VERSION_MAGIC, ?SMALL_BIG_EXT, S:8/big-unsigned-integer, 0,
Ds:S/binary>> ->
K = S - 1,
<<_:K/binary, Top>> = Ds,
isize_byte(Top)+K*8;
<<?VERSION_MAGIC, ?LARGE_BIG_EXT, S:32/big-unsigned-integer, 0,
Ds:S/binary>> ->
K = S - 1,
<<_:K/binary, Top>> = Ds,
isize_byte(Top)+K*8
end;
isize(0) -> 0.
%% big endian byte list
isize_bytes([0|L]) ->
isize_bytes(L);
isize_bytes([Top|L]) ->
isize_byte(Top) + length(L)*8.
%% Well could be improved
isize_byte(X) ->
if X >= 2#10000000 -> 8;
X >= 2#1000000 -> 7;
X >= 2#100000 -> 6;
X >= 2#10000 -> 5;
X >= 2#1000 -> 4;
X >= 2#100 -> 3;
X >= 2#10 -> 2;
X >= 2#1 -> 1;
true -> 0
end.
%% Convert integer into binary
%% When XLen is the wanted size in octets of the output
i2bin(X, XLen) ->
XSz = isize(X),
Sz = XLen*8,
if Sz < XSz ->
exit(integer_to_large);
true ->
(<<X:Sz/big-unsigned-integer>>)
end.
%% Convert a binary into an integer
%%
bin2i(X) ->
Sz = size(X)*8,
<<Y:Sz/big-unsigned-integer>> = X,
Y.
%%
%% Create a binary with constant bytes
%%
fill_bits(N,C) ->
list_to_binary(fill(N,C)).
fill(0,_C) -> [];
fill(1,C) -> [C];
fill(N,C) ->
Cs = fill(N div 2, C),
Cs1 = [Cs,Cs],
if N band 1 == 0 ->
Cs1;
true ->
[C,Cs,Cs]
end.
%% xor 2 binaries
%% xor_bits(XBits, YBits) ->
%% XSz = size(XBits)*8,
%% YSz = size(YBits)*8,
%% Sz = if XSz < YSz -> XSz; true -> YSz end, %% min
%% <<X:Sz, _/binary>> = XBits,
%% <<Y:Sz, _/binary>> = YBits,
%% <<(X bxor Y):Sz>>.
%% random/1
%% Generate N random bytes
%%
random(N) ->
crypto:strong_rand_bytes(N).
%% %%
%% %% Base 64 encode/decode
%% %%
%% b64_encode(Bs) when is_list(Bs) ->
%% base64:encode(Bs);
%% b64_encode(Bin) when is_binary(Bin) ->
%% base64:encode(Bin).
%% b64_decode(Bin) when is_binary(Bin) ->
%% base64:mime_decode(Bin);
%% b64_decode(Cs) when is_list(Cs) ->
%% base64:mime_decode(Cs).
