%% %% %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/8, 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(), #connection_states{}, #ssl_options{}, integer(), atom(), boolean(), der_cert()) -> #client_hello{}. %% %% Description: Creates a client hello message. %%-------------------------------------------------------------------- client_hello(Host, Port, ConnectionStates, SslOpts, Cache, CacheCb, Renegotiation, OwnCert) -> %% First client hello (two sent in DTLS ) uses empty Cookie client_hello(Host, Port, <<>>, ConnectionStates, SslOpts, Cache, CacheCb, Renegotiation, OwnCert). %%-------------------------------------------------------------------- -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(Host, 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. %%-------------------------------------------------------------------- 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()], #dtls_hs_state{}} | {retransmit, #dtls_hs_state{}}. % % 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{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). 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>>.