%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2007-2013. 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%
%%
%%
%%----------------------------------------------------------------------
%% Purpose: Handle TLS/SSL record protocol. (Parts that are not shared with DTLS)
%%----------------------------------------------------------------------
-module(tls_record).
-include("tls_record.hrl").
-include("ssl_internal.hrl").
-include("ssl_alert.hrl").
-include("tls_handshake.hrl").
-include("ssl_cipher.hrl").
%% Handling of incoming data
-export([get_tls_records/2]).
%% Decoding
-export([decode_cipher_text/2]).
%% Encoding
-export([encode_plain_text/4]).
%% Protocol version handling
-export([protocol_version/1, lowest_protocol_version/2,
highest_protocol_version/1, supported_protocol_versions/0,
is_acceptable_version/1, is_acceptable_version/2]).
-compile(inline).
%%====================================================================
%% Internal application API
%%====================================================================
%%--------------------------------------------------------------------
-spec get_tls_records(binary(), binary()) -> {[binary()], binary()} | #alert{}.
%%
%% Description: Given old buffer and new data from TCP, packs up a records
%% and returns it as a list of tls_compressed binaries also returns leftover
%% data
%%--------------------------------------------------------------------
get_tls_records(Data, <<>>) ->
get_tls_records_aux(Data, []);
get_tls_records(Data, Buffer) ->
get_tls_records_aux(list_to_binary([Buffer, Data]), []).
get_tls_records_aux(<<?BYTE(?APPLICATION_DATA),?BYTE(MajVer),?BYTE(MinVer),
?UINT16(Length), Data:Length/binary, Rest/binary>>,
Acc) ->
get_tls_records_aux(Rest, [#ssl_tls{type = ?APPLICATION_DATA,
version = {MajVer, MinVer},
fragment = Data} | Acc]);
get_tls_records_aux(<<?BYTE(?HANDSHAKE),?BYTE(MajVer),?BYTE(MinVer),
?UINT16(Length),
Data:Length/binary, Rest/binary>>, Acc) ->
get_tls_records_aux(Rest, [#ssl_tls{type = ?HANDSHAKE,
version = {MajVer, MinVer},
fragment = Data} | Acc]);
get_tls_records_aux(<<?BYTE(?ALERT),?BYTE(MajVer),?BYTE(MinVer),
?UINT16(Length), Data:Length/binary,
Rest/binary>>, Acc) ->
get_tls_records_aux(Rest, [#ssl_tls{type = ?ALERT,
version = {MajVer, MinVer},
fragment = Data} | Acc]);
get_tls_records_aux(<<?BYTE(?CHANGE_CIPHER_SPEC),?BYTE(MajVer),?BYTE(MinVer),
?UINT16(Length), Data:Length/binary, Rest/binary>>,
Acc) ->
get_tls_records_aux(Rest, [#ssl_tls{type = ?CHANGE_CIPHER_SPEC,
version = {MajVer, MinVer},
fragment = Data} | Acc]);
%% Matches an ssl v2 client hello message.
%% The server must be able to receive such messages, from clients that
%% are willing to use ssl v3 or higher, but have ssl v2 compatibility.
get_tls_records_aux(<<1:1, Length0:15, Data0:Length0/binary, Rest/binary>>,
Acc) ->
case Data0 of
<<?BYTE(?CLIENT_HELLO), ?BYTE(MajVer), ?BYTE(MinVer), _/binary>> ->
Length = Length0-1,
<<?BYTE(_), Data1:Length/binary>> = Data0,
Data = <<?BYTE(?CLIENT_HELLO), ?UINT24(Length), Data1/binary>>,
get_tls_records_aux(Rest, [#ssl_tls{type = ?HANDSHAKE,
version = {MajVer, MinVer},
fragment = Data} | Acc]);
_ ->
?ALERT_REC(?FATAL, ?HANDSHAKE_FAILURE)
end;
get_tls_records_aux(<<0:1, _CT:7, ?BYTE(_MajVer), ?BYTE(_MinVer),
?UINT16(Length), _/binary>>,
_Acc) when Length > ?MAX_CIPHER_TEXT_LENGTH ->
?ALERT_REC(?FATAL, ?RECORD_OVERFLOW);
get_tls_records_aux(<<1:1, Length0:15, _/binary>>,_Acc)
when Length0 > ?MAX_CIPHER_TEXT_LENGTH ->
?ALERT_REC(?FATAL, ?RECORD_OVERFLOW);
get_tls_records_aux(Data, Acc) ->
case size(Data) =< ?MAX_CIPHER_TEXT_LENGTH + ?INITIAL_BYTES of
true ->
{lists:reverse(Acc), Data};
false ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE)
end.
encode_plain_text(Type, Version, Data, ConnectionStates) ->
#connection_states{current_write=#connection_state{
compression_state=CompS0,
security_parameters=
#security_parameters{compression_algorithm=CompAlg}
}=CS0} = ConnectionStates,
{Comp, CompS1} = ssl_record:compress(CompAlg, Data, CompS0),
CS1 = CS0#connection_state{compression_state = CompS1},
{CipherFragment, CS2} = cipher(Type, Version, Comp, CS1),
CTBin = encode_tls_cipher_text(Type, Version, CipherFragment),
{CTBin, ConnectionStates#connection_states{current_write = CS2}}.
%%--------------------------------------------------------------------
-spec decode_cipher_text(#ssl_tls{}, #connection_states{}) ->
{#ssl_tls{}, #connection_states{}}| #alert{}.
%%
%% Description: Decode cipher text
%%--------------------------------------------------------------------
decode_cipher_text(#ssl_tls{type = Type, version = Version,
fragment = CipherFragment} = CipherText, ConnnectionStates0) ->
ReadState0 = ConnnectionStates0#connection_states.current_read,
#connection_state{compression_state = CompressionS0,
security_parameters = SecParams} = ReadState0,
CompressAlg = SecParams#security_parameters.compression_algorithm,
case decipher(Type, Version, CipherFragment, ReadState0) of
{PlainFragment, ReadState1} ->
{Plain, CompressionS1} = ssl_record:uncompress(CompressAlg,
PlainFragment, CompressionS0),
ConnnectionStates = ConnnectionStates0#connection_states{
current_read = ReadState1#connection_state{
compression_state = CompressionS1}},
{CipherText#ssl_tls{fragment = Plain}, ConnnectionStates};
#alert{} = Alert ->
Alert
end.
%%--------------------------------------------------------------------
-spec protocol_version(tls_atom_version() | tls_version()) ->
tls_version() | tls_atom_version().
%%
%% Description: Creates a protocol version record from a version atom
%% or vice versa.
%%--------------------------------------------------------------------
protocol_version('tlsv1.2') ->
{3, 3};
protocol_version('tlsv1.1') ->
{3, 2};
protocol_version(tlsv1) ->
{3, 1};
protocol_version(sslv3) ->
{3, 0};
protocol_version(sslv2) -> %% Backwards compatibility
{2, 0};
protocol_version({3, 3}) ->
'tlsv1.2';
protocol_version({3, 2}) ->
'tlsv1.1';
protocol_version({3, 1}) ->
tlsv1;
protocol_version({3, 0}) ->
sslv3.
%%--------------------------------------------------------------------
-spec lowest_protocol_version(tls_version(), tls_version()) -> tls_version().
%%
%% Description: Lowes protocol version of two given versions
%%--------------------------------------------------------------------
lowest_protocol_version(Version = {M, N}, {M, O}) when N < O ->
Version;
lowest_protocol_version({M, _},
Version = {M, _}) ->
Version;
lowest_protocol_version(Version = {M,_},
{N, _}) when M < N ->
Version;
lowest_protocol_version(_,Version) ->
Version.
%%--------------------------------------------------------------------
-spec highest_protocol_version([tls_version()]) -> tls_version().
%%
%% Description: Highest protocol version present in a list
%%--------------------------------------------------------------------
highest_protocol_version([]) ->
highest_protocol_version();
highest_protocol_version(Versions) ->
[Ver | Vers] = Versions,
highest_protocol_version(Ver, Vers).
highest_protocol_version(Version, []) ->
Version;
highest_protocol_version(Version = {N, M}, [{N, O} | Rest]) when M > O ->
highest_protocol_version(Version, Rest);
highest_protocol_version({M, _}, [Version = {M, _} | Rest]) ->
highest_protocol_version(Version, Rest);
highest_protocol_version(Version = {M,_}, [{N,_} | Rest]) when M > N ->
highest_protocol_version(Version, Rest);
highest_protocol_version(_, [Version | Rest]) ->
highest_protocol_version(Version, Rest).
%%--------------------------------------------------------------------
-spec supported_protocol_versions() -> [tls_version()].
%%
%% Description: Protocol versions supported
%%--------------------------------------------------------------------
supported_protocol_versions() ->
Fun = fun(Version) ->
protocol_version(Version)
end,
case application:get_env(ssl, protocol_version) of
undefined ->
lists:map(Fun, supported_protocol_versions([]));
{ok, []} ->
lists:map(Fun, supported_protocol_versions([]));
{ok, Vsns} when is_list(Vsns) ->
Versions = lists:filter(fun is_acceptable_version/1, lists:map(Fun, Vsns)),
supported_protocol_versions(Versions);
{ok, Vsn} ->
Versions = lists:filter(fun is_acceptable_version/1, [Fun(Vsn)]),
supported_protocol_versions(Versions)
end.
supported_protocol_versions([]) ->
Vsns = case sufficient_tlsv1_2_crypto_support() of
true ->
?ALL_SUPPORTED_VERSIONS;
false ->
?MIN_SUPPORTED_VERSIONS
end,
application:set_env(ssl, protocol_version, Vsns),
Vsns;
supported_protocol_versions([_|_] = Vsns) ->
Vsns.
%%--------------------------------------------------------------------
-spec is_acceptable_version(tls_version()) -> boolean().
-spec is_acceptable_version(tls_version(), Supported :: [tls_version()]) -> boolean().
%%
%% Description: ssl version 2 is not acceptable security risks are too big.
%%
%%--------------------------------------------------------------------
is_acceptable_version({N,_})
when N >= ?LOWEST_MAJOR_SUPPORTED_VERSION ->
true;
is_acceptable_version(_) ->
false.
is_acceptable_version({N,_} = Version, Versions)
when N >= ?LOWEST_MAJOR_SUPPORTED_VERSION ->
lists:member(Version, Versions);
is_acceptable_version(_,_) ->
false.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
encode_tls_cipher_text(Type, {MajVer, MinVer}, Fragment) ->
Length = erlang:iolist_size(Fragment),
[<<?BYTE(Type), ?BYTE(MajVer), ?BYTE(MinVer), ?UINT16(Length)>>, Fragment].
cipher(Type, Version, Fragment,
#connection_state{cipher_state = CipherS0,
sequence_number = SeqNo,
security_parameters=
#security_parameters{bulk_cipher_algorithm =
BCA}
} = WriteState0) ->
MacHash = calc_mac_hash(Type, Version, Fragment, WriteState0),
{CipherFragment, CipherS1} =
ssl_cipher:cipher(BCA, CipherS0, MacHash, Fragment, Version),
WriteState = WriteState0#connection_state{cipher_state=CipherS1},
{CipherFragment, WriteState#connection_state{sequence_number = SeqNo+1}}.
decipher(Type, Version, CipherFragment,
#connection_state{sequence_number = SeqNo} = ReadState) ->
SP = ReadState#connection_state.security_parameters,
BCA = SP#security_parameters.bulk_cipher_algorithm,
HashSz = SP#security_parameters.hash_size,
CipherS0 = ReadState#connection_state.cipher_state,
case ssl_cipher:decipher(BCA, HashSz, CipherS0, CipherFragment, Version) of
{PlainFragment, Mac, CipherS1} ->
CS1 = ReadState#connection_state{cipher_state = CipherS1},
MacHash = calc_mac_hash(Type, Version, PlainFragment, ReadState),
case ssl_record:is_correct_mac(Mac, MacHash) of
true ->
{PlainFragment,
CS1#connection_state{sequence_number = SeqNo+1}};
false ->
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC)
end;
#alert{} = Alert ->
Alert
end.
mac_hash({_,_}, ?NULL, _MacSecret, _SeqNo, _Type,
_Length, _Fragment) ->
<<>>;
mac_hash({3, 0}, MacAlg, MacSecret, SeqNo, Type, Length, Fragment) ->
ssl_v3:mac_hash(MacAlg, MacSecret, SeqNo, Type, Length, Fragment);
mac_hash({3, N} = Version, MacAlg, MacSecret, SeqNo, Type, Length, Fragment)
when N =:= 1; N =:= 2; N =:= 3 ->
tls_v1:mac_hash(MacAlg, MacSecret, SeqNo, Type, Version,
Length, Fragment).
highest_protocol_version() ->
highest_protocol_version(supported_protocol_versions()).
sufficient_tlsv1_2_crypto_support() ->
CryptoSupport = crypto:supports(),
proplists:get_bool(sha256, proplists:get_value(hashs, CryptoSupport)).
calc_mac_hash(Type, Version,
PlainFragment, #connection_state{sequence_number = SeqNo,
mac_secret = MacSecret,
security_parameters =
SecPars}) ->
Length = erlang:iolist_size(PlainFragment),
mac_hash(Version, SecPars#security_parameters.mac_algorithm,
MacSecret, SeqNo, Type,
Length, PlainFragment).
