diff options
Diffstat (limited to 'lib/ssl/src/dtls_handshake.erl')
| -rw-r--r-- | lib/ssl/src/dtls_handshake.erl | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/lib/ssl/src/dtls_handshake.erl b/lib/ssl/src/dtls_handshake.erl index b25daa59d9..26e8ce7503 100644 --- a/lib/ssl/src/dtls_handshake.erl +++ b/lib/ssl/src/dtls_handshake.erl @@ -16,3 +16,413 @@ %% %% %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, 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). |