%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2013-2013. 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%
-module(dtls_handshake).
-include("dtls_handshake.hrl").
-include("dtls_record.hrl").
-include("ssl_internal.hrl").
-export([client_hello/9, hello/3, get_dtls_handshake/2,
dtls_handshake_new_flight/1, dtls_handshake_new_epoch/1,
encode_handshake/4]).
%%====================================================================
%% Internal application API
%%====================================================================
%%--------------------------------------------------------------------
-spec client_hello(host(), inet:port_number(), term(), #connection_states{},
#ssl_options{}, integer(), atom(), boolean(), der_cert()) ->
#client_hello{}.
%%
%% Description: Creates a client hello message.
%%--------------------------------------------------------------------
client_hello(Host, Port, Cookie, ConnectionStates,
#ssl_options{versions = Versions,
ciphers = UserSuites
} = SslOpts,
Cache, CacheCb, Renegotiation, OwnCert) ->
Version = dtls_record:highest_protocol_version(Versions),
Pending = ssl_record:pending_connection_state(ConnectionStates, read),
SecParams = Pending#connection_state.security_parameters,
CipherSuites = ssl_handshake:available_suites(UserSuites, Version),
Extensions = ssl_handshake:client_hello_extensions(Version, CipherSuites,
SslOpts, ConnectionStates, Renegotiation),
Id = ssl_session:client_id({Host, Port, SslOpts}, Cache, CacheCb, OwnCert),
#client_hello{session_id = Id,
client_version = Version,
cipher_suites = ssl_handshake:cipher_suites(CipherSuites, Renegotiation),
compression_methods = ssl_record:compressions(),
random = SecParams#security_parameters.client_random,
cookie = Cookie,
extensions = Extensions
}.
hello(Address, Port,
#ssl_tls{epoch = _Epoch, record_seq = _Seq,
version = Version} = Record) ->
{[{Hello, _}], _, _} =
get_dtls_handshake(Record,
dtls_handshake_new_flight(undefined)),
#client_hello{client_version = {Major, Minor},
random = Random,
session_id = SessionId,
cipher_suites = CipherSuites,
compression_methods = CompressionMethods} = Hello,
CookieData = [address_to_bin(Address, Port),
<<?BYTE(Major), ?BYTE(Minor)>>,
Random, SessionId, CipherSuites, CompressionMethods],
Cookie = crypto:hmac(sha, <<"secret">>, CookieData),
case Hello of
#client_hello{cookie = Cookie} ->
accept;
_ ->
%% generate HelloVerifyRequest
HelloVerifyRequest = encode_handshake(#hello_verify_request{protocol_version = Version,
cookie = Cookie},
Version, 0, 1400),
{reply, HelloVerifyRequest}
end.
address_to_bin({A,B,C,D}, Port) ->
<<0:80,16#ffff:16,A,B,C,D,Port:16>>;
address_to_bin({A,B,C,D,E,F,G,H}, Port) ->
<<A:16,B:16,C:16,D:16,E:16,F:16,G:16,H:16,Port:16>>.
%%--------------------------------------------------------------------
encode_handshake(Package, Version, MsgSeq, Mss) ->
{MsgType, Bin} = enc_hs(Package, Version),
Len = byte_size(Bin),
HsHistory = [MsgType, ?uint24(Len), ?uint16(MsgSeq), ?uint24(0), ?uint24(Len), Bin],
BinMsg = dtls_split_handshake(Mss, MsgType, Len, MsgSeq, Bin, 0, []),
{HsHistory, BinMsg}.
%--------------------------------------------------------------------
-spec get_dtls_handshake(#ssl_tls{}, #dtls_hs_state{} | binary()) ->
{[dtls_handshake()], #ssl_tls{}}.
%
% Description: Given a DTLS state and new data from ssl_record, collects
% and returns it as a list of handshake messages, also returns a new
% DTLS state
%--------------------------------------------------------------------
% get_dtls_handshake(Record, <<>>) ->
% get_dtls_handshake_aux(Record, dtls_hs_state_init());
get_dtls_handshake(Record, HsState) ->
get_dtls_handshake_aux(Record, HsState).
%--------------------------------------------------------------------
-spec dtls_handshake_new_epoch(#dtls_hs_state{}) -> #dtls_hs_state{}.
%
% Description: Reset the DTLS decoder state for a new Epoch
%--------------------------------------------------------------------
% dtls_handshake_new_epoch(<<>>) ->
% dtls_hs_state_init();
dtls_handshake_new_epoch(HsState) ->
HsState#dtls_hs_state{highest_record_seq = 0,
starting_read_seq = HsState#dtls_hs_state.current_read_seq,
fragments = gb_trees:empty(), completed = []}.
%--------------------------------------------------------------------
-spec dtls_handshake_new_flight(integer() | undefined) -> #dtls_hs_state{}.
%
% Description: Init the DTLS decoder state for a new Flight
dtls_handshake_new_flight(ExpectedReadReq) ->
#dtls_hs_state{current_read_seq = ExpectedReadReq,
highest_record_seq = 0,
starting_read_seq = 0,
fragments = gb_trees:empty(), completed = []}.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
dtls_split_handshake(Mss, MsgType, Len, MsgSeq, Bin, Offset, Acc)
when byte_size(Bin) + 12 < Mss ->
FragmentLen = byte_size(Bin),
BinMsg = [MsgType, ?uint24(Len), ?uint16(MsgSeq), ?uint24(Offset), ?uint24(FragmentLen), Bin],
lists:reverse([BinMsg|Acc]);
dtls_split_handshake(Mss, MsgType, Len, MsgSeq, Bin, Offset, Acc) ->
FragmentLen = Mss - 12,
<<Fragment:FragmentLen/bytes, Rest/binary>> = Bin,
BinMsg = [MsgType, ?uint24(Len), ?uint16(MsgSeq), ?uint24(Offset), ?uint24(FragmentLen), Fragment],
dtls_split_handshake(Mss, MsgType, Len, MsgSeq, Rest, Offset + FragmentLen, [BinMsg|Acc]).
get_dtls_handshake_aux(#ssl_tls{version = Version,
record_seq = SeqNo,
fragment = Data}, HsState) ->
get_dtls_handshake_aux(Version, SeqNo, Data, HsState).
get_dtls_handshake_aux(Version, SeqNo,
<<?BYTE(Type), ?UINT24(Length),
?UINT16(MessageSeq),
?UINT24(FragmentOffset), ?UINT24(FragmentLength),
Body:FragmentLength/binary, Rest/binary>>,
HsState0) ->
case reassemble_dtls_fragment(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body, HsState0) of
{retransmit, HsState1} ->
case Rest of
<<>> ->
{retransmit, HsState1};
_ ->
get_dtls_handshake_aux(Version, SeqNo, Rest, HsState1)
end;
{HsState1, HighestSeqNo, MsgBody} ->
HsState2 = dec_dtls_fragment(Version, HighestSeqNo, Type, Length, MessageSeq, MsgBody, HsState1),
HsState3 = process_dtls_fragments(Version, HsState2),
get_dtls_handshake_aux(Version, SeqNo, Rest, HsState3);
HsState2 ->
HsState3 = process_dtls_fragments(Version, HsState2),
get_dtls_handshake_aux(Version, SeqNo, Rest, HsState3)
end;
get_dtls_handshake_aux(_Version, _SeqNo, <<>>, HsState) ->
{lists:reverse(HsState#dtls_hs_state.completed),
HsState#dtls_hs_state.highest_record_seq,
HsState#dtls_hs_state{completed = []}}.
dec_dtls_fragment(Version, SeqNo, Type, Length, MessageSeq, MsgBody,
HsState = #dtls_hs_state{highest_record_seq = HighestSeqNo, completed = Acc}) ->
Raw = <<?BYTE(Type), ?UINT24(Length), ?UINT16(MessageSeq), ?UINT24(0), ?UINT24(Length), MsgBody/binary>>,
H = decode_handshake(Version, Type, MsgBody),
HsState#dtls_hs_state{completed = [{H,Raw}|Acc], highest_record_seq = erlang:max(HighestSeqNo, SeqNo)}.
process_dtls_fragments(Version,
HsState0 = #dtls_hs_state{current_read_seq = CurrentReadSeq,
fragments = Fragments0}) ->
case gb_trees:is_empty(Fragments0) of
true ->
HsState0;
_ ->
case gb_trees:smallest(Fragments0) of
{CurrentReadSeq, {SeqNo, Type, Length, CurrentReadSeq, {Length, [{0, Length}], MsgBody}}} ->
HsState1 = dtls_hs_state_process_seq(HsState0),
HsState2 = dec_dtls_fragment(Version, SeqNo, Type, Length, CurrentReadSeq, MsgBody, HsState1),
process_dtls_fragments(Version, HsState2);
_ ->
HsState0
end
end.
dtls_hs_state_process_seq(HsState0 = #dtls_hs_state{current_read_seq = CurrentReadSeq,
fragments = Fragments0}) ->
Fragments1 = gb_trees:delete_any(CurrentReadSeq, Fragments0),
HsState0#dtls_hs_state{current_read_seq = CurrentReadSeq + 1,
fragments = Fragments1}.
dtls_hs_state_add_fragment(MessageSeq, Fragment, HsState0 = #dtls_hs_state{fragments = Fragments0}) ->
Fragments1 = gb_trees:enter(MessageSeq, Fragment, Fragments0),
HsState0#dtls_hs_state{fragments = Fragments1}.
reassemble_dtls_fragment(SeqNo, Type, Length, MessageSeq, 0, Length,
Body, HsState0 = #dtls_hs_state{current_read_seq = undefined})
when Type == ?CLIENT_HELLO;
Type == ?SERVER_HELLO;
Type == ?HELLO_VERIFY_REQUEST ->
%% First message, should be client hello
%% return the current message and set the next expected Sequence
%%
%% Note: this could (should?) be restricted further, ClientHello and
%% HelloVerifyRequest have to have message_seq = 0, ServerHello
%% can have a message_seq of 0 or 1
%%
{HsState0#dtls_hs_state{current_read_seq = MessageSeq + 1}, SeqNo, Body};
reassemble_dtls_fragment(_SeqNo, _Type, Length, _MessageSeq, _, Length,
_Body, HsState = #dtls_hs_state{current_read_seq = undefined}) ->
%% not what we expected, drop it
HsState;
reassemble_dtls_fragment(SeqNo, _Type, Length, MessageSeq, 0, Length,
Body, HsState0 =
#dtls_hs_state{starting_read_seq = StartingReadSeq})
when MessageSeq < StartingReadSeq ->
%% this has to be the start of a new flight, let it through
%%
%% Note: this could (should?) be restricted further, the first message of a
%% new flight has to have message_seq = 0
%%
HsState = dtls_hs_state_process_seq(HsState0),
{HsState, SeqNo, Body};
reassemble_dtls_fragment(_SeqNo, _Type, Length, MessageSeq, 0, Length,
_Body, HsState =
#dtls_hs_state{current_read_seq = CurrentReadSeq})
when MessageSeq < CurrentReadSeq ->
{retransmit, HsState};
reassemble_dtls_fragment(_SeqNo, _Type, Length, MessageSeq, 0, Length,
_Body, HsState = #dtls_hs_state{current_read_seq = CurrentReadSeq})
when MessageSeq < CurrentReadSeq ->
HsState;
reassemble_dtls_fragment(SeqNo, _Type, Length, MessageSeq, 0, Length,
Body, HsState0 = #dtls_hs_state{current_read_seq = MessageSeq}) ->
%% Message fully contained and it's the current seq
HsState1 = dtls_hs_state_process_seq(HsState0),
{HsState1, SeqNo, Body};
reassemble_dtls_fragment(SeqNo, Type, Length, MessageSeq, 0, Length,
Body, HsState) ->
%% Message fully contained and it's the NOT the current seq -> buffer
Fragment = {SeqNo, Type, Length, MessageSeq,
dtls_fragment_init(Length, 0, Length, Body)},
dtls_hs_state_add_fragment(MessageSeq, Fragment, HsState);
reassemble_dtls_fragment(_SeqNo, _Type, Length, MessageSeq, FragmentOffset, FragmentLength,
_Body,
HsState = #dtls_hs_state{current_read_seq = CurrentReadSeq})
when FragmentOffset + FragmentLength == Length andalso MessageSeq == (CurrentReadSeq - 1) ->
{retransmit, HsState};
reassemble_dtls_fragment(_SeqNo, _Type, _Length, MessageSeq, _FragmentOffset, _FragmentLength,
_Body,
HsState = #dtls_hs_state{current_read_seq = CurrentReadSeq})
when MessageSeq < CurrentReadSeq ->
HsState;
reassemble_dtls_fragment(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body,
HsState = #dtls_hs_state{fragments = Fragments0}) ->
case gb_trees:lookup(MessageSeq, Fragments0) of
{value, Fragment} ->
dtls_fragment_reassemble(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body, Fragment, HsState);
none ->
dtls_fragment_start(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body, HsState)
end.
dtls_fragment_start(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body, HsState = #dtls_hs_state{fragments = Fragments0}) ->
Fragment = {SeqNo, Type, Length, MessageSeq,
dtls_fragment_init(Length, FragmentOffset, FragmentLength, Body)},
Fragments1 = gb_trees:insert(MessageSeq, Fragment, Fragments0),
HsState#dtls_hs_state{fragments = Fragments1}.
dtls_fragment_reassemble(SeqNo, Type, Length, MessageSeq,
FragmentOffset, FragmentLength,
Body,
{LastSeqNo, Type, Length, MessageSeq, FragBuffer0},
HsState = #dtls_hs_state{fragments = Fragments0}) ->
FragBuffer1 = dtls_fragment_add(FragBuffer0, FragmentOffset, FragmentLength, Body),
Fragment = {erlang:max(SeqNo, LastSeqNo), Type, Length, MessageSeq, FragBuffer1},
Fragments1 = gb_trees:enter(MessageSeq, Fragment, Fragments0),
HsState#dtls_hs_state{fragments = Fragments1};
%% Type, Length or Seq mismatch, drop everything...
%% Note: the RFC is not clear on how to handle this...
dtls_fragment_reassemble(_SeqNo, _Type, _Length, MessageSeq,
_FragmentOffset, _FragmentLength, _Body, _Fragment,
HsState = #dtls_hs_state{fragments = Fragments0}) ->
Fragments1 = gb_trees:delete_any(MessageSeq, Fragments0),
HsState#dtls_hs_state{fragments = Fragments1}.
dtls_fragment_add({Length, FragmentList0, Bin0}, FragmentOffset, FragmentLength, Body) ->
Bin1 = dtls_fragment_bin_add(FragmentOffset, FragmentLength, Body, Bin0),
FragmentList1 = add_fragment(FragmentList0, {FragmentOffset, FragmentLength}),
{Length, FragmentList1, Bin1}.
dtls_fragment_init(Length, 0, Length, Body) ->
{Length, [{0, Length}], Body};
dtls_fragment_init(Length, FragmentOffset, FragmentLength, Body) ->
Bin = dtls_fragment_bin_add(FragmentOffset, FragmentLength, Body, <<0:(Length*8)>>),
{Length, [{FragmentOffset, FragmentOffset + FragmentLength}], Bin}.
dtls_fragment_bin_add(FragmentOffset, FragmentLength, Add, Buffer) ->
<<First:FragmentOffset/bytes, _:FragmentLength/bytes, Rest/binary>> = Buffer,
<<First/binary, Add/binary, Rest/binary>>.
merge_fragment_list([], Fragment, Acc) ->
lists:reverse([Fragment|Acc]);
merge_fragment_list([H = {_, HEnd}|Rest], Frag = {FStart, _}, Acc)
when FStart > HEnd ->
merge_fragment_list(Rest, Frag, [H|Acc]);
merge_fragment_list(Rest = [{HStart, _HEnd}|_], Frag = {_FStart, FEnd}, Acc)
when FEnd < HStart ->
lists:reverse(Acc) ++ [Frag|Rest];
merge_fragment_list([{HStart, HEnd}|Rest], _Frag = {FStart, FEnd}, Acc)
when
FStart =< HEnd orelse FEnd >= HStart ->
Start = erlang:min(HStart, FStart),
End = erlang:max(HEnd, FEnd),
NewFrag = {Start, End},
merge_fragment_list(Rest, NewFrag, Acc).
add_fragment(List, {FragmentOffset, FragmentLength}) ->
merge_fragment_list(List, {FragmentOffset, FragmentOffset + FragmentLength}, []).
enc_hs(#hello_verify_request{protocol_version = {Major, Minor},
cookie = Cookie}, _Version) ->
CookieLength = byte_size(Cookie),
{?HELLO_VERIFY_REQUEST, <<?BYTE(Major), ?BYTE(Minor),
?BYTE(CookieLength),
Cookie/binary>>};
enc_hs(#client_hello{client_version = {Major, Minor},
random = Random,
session_id = SessionID,
cookie = Cookie,
cipher_suites = CipherSuites,
compression_methods = CompMethods,
extensions = HelloExtensions}, Version) ->
SIDLength = byte_size(SessionID),
BinCookie = enc_client_hello_cookie(Version, Cookie),
BinCompMethods = list_to_binary(CompMethods),
CmLength = byte_size(BinCompMethods),
BinCipherSuites = list_to_binary(CipherSuites),
CsLength = byte_size(BinCipherSuites),
ExtensionsBin = ssl_handshake:encode_hello_extensions(HelloExtensions),
{?CLIENT_HELLO, <<?BYTE(Major), ?BYTE(Minor), Random:32/binary,
?BYTE(SIDLength), SessionID/binary,
BinCookie/binary,
?UINT16(CsLength), BinCipherSuites/binary,
?BYTE(CmLength), BinCompMethods/binary, ExtensionsBin/binary>>};
enc_hs(HandshakeMsg, Version) ->
ssl_handshake:encode_handshake(HandshakeMsg, Version).
enc_client_hello_cookie(_, <<>>) ->
<<>>;
enc_client_hello_cookie(_, Cookie) ->
CookieLength = byte_size(Cookie),
<<?BYTE(CookieLength), Cookie/binary>>.
decode_handshake(_Version, ?CLIENT_HELLO, <<?BYTE(Major), ?BYTE(Minor), Random:32/binary,
?BYTE(SID_length), Session_ID:SID_length/binary,
?BYTE(Cookie_length), Cookie:Cookie_length/binary,
?UINT16(Cs_length), CipherSuites:Cs_length/binary,
?BYTE(Cm_length), Comp_methods:Cm_length/binary,
Extensions/binary>>) ->
DecodedExtensions = ssl_handshake:decode_hello_extensions(Extensions),
#client_hello{
client_version = {Major,Minor},
random = Random,
session_id = Session_ID,
cookie = Cookie,
cipher_suites = ssl_handshake:decode_suites('2_bytes', CipherSuites),
compression_methods = Comp_methods,
extensions = DecodedExtensions
};
decode_handshake(_Version, ?HELLO_VERIFY_REQUEST, <<?BYTE(Major), ?BYTE(Minor),
?BYTE(CookieLength), Cookie:CookieLength/binary>>) ->
#hello_verify_request{
protocol_version = {Major,Minor},
cookie = Cookie};
decode_handshake(Version, Tag, Msg) ->
ssl_handshake:decode_handshake(Version, Tag, Msg).
