diff options
Diffstat (limited to 'lib/ssl/src/dtls_record.erl')
| -rw-r--r-- | lib/ssl/src/dtls_record.erl | 366 |
1 files changed, 366 insertions, 0 deletions
diff --git a/lib/ssl/src/dtls_record.erl b/lib/ssl/src/dtls_record.erl index 2469a7d26c..f667458a10 100644 --- a/lib/ssl/src/dtls_record.erl +++ b/lib/ssl/src/dtls_record.erl @@ -15,4 +15,370 @@ %% under the License. %% %% %CopyrightEnd% + +%% +%%---------------------------------------------------------------------- +%% Purpose: Handle DTLS record protocol. (Parts that are not shared with SSL/TLS) +%%---------------------------------------------------------------------- -module(dtls_record). + +-include("dtls_record.hrl"). +-include("ssl_internal.hrl"). +-include("ssl_alert.hrl"). +-include("dtls_handshake.hrl"). +-include("ssl_cipher.hrl"). + +%% Handling of incoming data +-export([get_dtls_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/2, cipher/4, decipher/2]). + +-export([init_connection_state_seq/2, current_connection_state_epoch/2, + set_connection_state_by_epoch/3, connection_state_by_epoch/3]). + +-compile(inline). + +%%==================================================================== +%% Internal application API +%%==================================================================== + +%%-------------------------------------------------------------------- +-spec get_dtls_records(binary(), binary()) -> {[binary()], binary()} | #alert{}. +%% +%% Description: Given old buffer and new data from UDP/SCTP, packs up a records +%% and returns it as a list of tls_compressed binaries also returns leftover +%% data +%%-------------------------------------------------------------------- +get_dtls_records(Data, <<>>) -> + get_dtls_records_aux(Data, []); +get_dtls_records(Data, Buffer) -> + get_dtls_records_aux(list_to_binary([Buffer, Data]), []). + +get_dtls_records_aux(<<?BYTE(?APPLICATION_DATA),?BYTE(MajVer),?BYTE(MinVer), + ?UINT16(Epoch), ?UINT48(SequenceNumber), + ?UINT16(Length), Data:Length/binary, Rest/binary>>, + Acc) -> + get_dtls_records_aux(Rest, [#ssl_tls{type = ?APPLICATION_DATA, + version = {MajVer, MinVer}, + epoch = Epoch, record_seq = SequenceNumber, + fragment = Data} | Acc]); +get_dtls_records_aux(<<?BYTE(?HANDSHAKE),?BYTE(MajVer),?BYTE(MinVer), + ?UINT16(Epoch), ?UINT48(SequenceNumber), + ?UINT16(Length), + Data:Length/binary, Rest/binary>>, Acc) when MajVer >= 128 -> + get_dtls_records_aux(Rest, [#ssl_tls{type = ?HANDSHAKE, + version = {MajVer, MinVer}, + epoch = Epoch, record_seq = SequenceNumber, + fragment = Data} | Acc]); +get_dtls_records_aux(<<?BYTE(?ALERT),?BYTE(MajVer),?BYTE(MinVer), + ?UINT16(Epoch), ?UINT48(SequenceNumber), + ?UINT16(Length), Data:Length/binary, + Rest/binary>>, Acc) -> + get_dtls_records_aux(Rest, [#ssl_tls{type = ?ALERT, + version = {MajVer, MinVer}, + epoch = Epoch, record_seq = SequenceNumber, + fragment = Data} | Acc]); +get_dtls_records_aux(<<?BYTE(?CHANGE_CIPHER_SPEC),?BYTE(MajVer),?BYTE(MinVer), + ?UINT16(Epoch), ?UINT48(SequenceNumber), + ?UINT16(Length), Data:Length/binary, Rest/binary>>, + Acc) -> + get_dtls_records_aux(Rest, [#ssl_tls{type = ?CHANGE_CIPHER_SPEC, + version = {MajVer, MinVer}, + epoch = Epoch, record_seq = SequenceNumber, + fragment = Data} | Acc]); + +get_dtls_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_dtls_records_aux(<<1:1, Length0:15, _/binary>>,_Acc) + when Length0 > ?MAX_CIPHER_TEXT_LENGTH -> + ?ALERT_REC(?FATAL, ?RECORD_OVERFLOW); + +get_dtls_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, + #connection_state{ + compression_state = CompS0, + epoch = Epoch, + sequence_number = Seq, + security_parameters= + #security_parameters{compression_algorithm = CompAlg} + }= CS0) -> + {Comp, CompS1} = ssl_record:compress(CompAlg, Data, CompS0), + CS1 = CS0#connection_state{compression_state = CompS1}, + {CipherText, CS2} = cipher(Type, Version, Comp, CS1), + CTBin = encode_tls_cipher_text(Type, Version, Epoch, Seq, CipherText), + {CTBin, CS2}. + +decode_cipher_text(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(CipherText, ReadState0) of + {Compressed, ReadState1} -> + {Plain, CompressionS1} = ssl_record:uncompress(CompressAlg, + Compressed, CompressionS0), + ConnnectionStates = ConnnectionStates0#connection_states{ + current_read = ReadState1#connection_state{ + compression_state = CompressionS1}}, + {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('dtlsv1.2') -> + {254, 253}; +protocol_version(dtlsv1) -> + {254, 255}; +protocol_version({254, 253}) -> + 'dtlsv1.2'; +protocol_version({254, 255}) -> + dtlsv1. +%%-------------------------------------------------------------------- +-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([Ver | Vers]) -> + 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, dtls_protocol_version) of + undefined -> + lists:map(Fun, supported_protocol_versions([])); + {ok, []} -> + lists:map(Fun, supported_protocol_versions([])); + {ok, Vsns} when is_list(Vsns) -> + supported_protocol_versions(Vsns); + {ok, Vsn} -> + supported_protocol_versions([Vsn]) + end. + +supported_protocol_versions([]) -> + Vsns = supported_connection_protocol_versions([]), + application:set_env(ssl, dtls_protocol_version, Vsns), + Vsns; + +supported_protocol_versions([_|_] = Vsns) -> + Vsns. + +supported_connection_protocol_versions([]) -> + ?ALL_DATAGRAM_SUPPORTED_VERSIONS. + +%%-------------------------------------------------------------------- +-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(Version, Versions) -> + lists:member(Version, Versions). + + +%%-------------------------------------------------------------------- +-spec init_connection_state_seq(tls_version(), #connection_states{}) -> + #connection_state{}. +%% +%% Description: Copy the read sequence number to the write sequence number +%% This is only valid for DTLS in the first client_hello +%%-------------------------------------------------------------------- +init_connection_state_seq({254, _}, + #connection_states{ + current_read = Read = #connection_state{epoch = 0}, + current_write = Write = #connection_state{epoch = 0}} = CS0) -> + CS0#connection_states{current_write = + Write#connection_state{ + sequence_number = Read#connection_state.sequence_number}}; +init_connection_state_seq(_, CS) -> + CS. + +%%-------------------------------------------------------- +-spec current_connection_state_epoch(#connection_states{}, read | write) -> + integer(). +%% +%% Description: Returns the epoch the connection_state record +%% that is currently defined as the current conection state. +%%-------------------------------------------------------------------- +current_connection_state_epoch(#connection_states{current_read = Current}, + read) -> + Current#connection_state.epoch; +current_connection_state_epoch(#connection_states{current_write = Current}, + write) -> + Current#connection_state.epoch. + +%%-------------------------------------------------------------------- + +-spec connection_state_by_epoch(#connection_states{}, integer(), read | write) -> + #connection_state{}. +%% +%% Description: Returns the instance of the connection_state record +%% that is defined by the Epoch. +%%-------------------------------------------------------------------- +connection_state_by_epoch(#connection_states{current_read = CS}, Epoch, read) + when CS#connection_state.epoch == Epoch -> + CS; +connection_state_by_epoch(#connection_states{pending_read = CS}, Epoch, read) + when CS#connection_state.epoch == Epoch -> + CS; +connection_state_by_epoch(#connection_states{current_write = CS}, Epoch, write) + when CS#connection_state.epoch == Epoch -> + CS; +connection_state_by_epoch(#connection_states{pending_write = CS}, Epoch, write) + when CS#connection_state.epoch == Epoch -> + CS. +%%-------------------------------------------------------------------- +-spec set_connection_state_by_epoch(#connection_states{}, + #connection_state{}, read | write) -> ok. +%% +%% Description: Returns the instance of the connection_state record +%% that is defined by the Epoch. +%%-------------------------------------------------------------------- +set_connection_state_by_epoch(ConnectionStates0 = + #connection_states{current_read = CS}, + NewCS = #connection_state{epoch = Epoch}, read) + when CS#connection_state.epoch == Epoch -> + ConnectionStates0#connection_states{current_read = NewCS}; + +set_connection_state_by_epoch(ConnectionStates0 = + #connection_states{pending_read = CS}, + NewCS = #connection_state{epoch = Epoch}, read) + when CS#connection_state.epoch == Epoch -> + ConnectionStates0#connection_states{pending_read = NewCS}; + +set_connection_state_by_epoch(ConnectionStates0 = + #connection_states{current_write = CS}, + NewCS = #connection_state{epoch = Epoch}, write) + when CS#connection_state.epoch == Epoch -> + ConnectionStates0#connection_states{current_write = NewCS}; + +set_connection_state_by_epoch(ConnectionStates0 = + #connection_states{pending_write = CS}, + NewCS = #connection_state{epoch = Epoch}, write) + when CS#connection_state.epoch == Epoch -> + ConnectionStates0#connection_states{pending_write = NewCS}. + +%%-------------------------------------------------------------------- +%%% Internal functions +%%-------------------------------------------------------------------- +encode_tls_cipher_text(Type, {MajVer, MinVer}, Epoch, Seq, Fragment) -> + Length = erlang:iolist_size(Fragment), + [<<?BYTE(Type), ?BYTE(MajVer), ?BYTE(MinVer), ?UINT16(Epoch), + ?UINT48(Seq), ?UINT16(Length)>>, Fragment]. + +cipher(Type, Version, Fragment, CS0) -> + Length = erlang:iolist_size(Fragment), + {MacHash, CS1=#connection_state{cipher_state = CipherS0, + security_parameters= + #security_parameters{bulk_cipher_algorithm = + BCA} + }} = + hash_and_bump_seqno(CS0, Type, Version, Length, Fragment), + {Ciphered, CipherS1} = ssl_cipher:cipher(BCA, CipherS0, MacHash, Fragment, Version), + CS2 = CS1#connection_state{cipher_state=CipherS1}, + {Ciphered, CS2}. + +decipher(TLS=#ssl_tls{type=Type, version=Version={254, _}, + epoch = Epoch, record_seq = SeqNo, + fragment=Fragment}, CS0) -> + SP = CS0#connection_state.security_parameters, + BCA = SP#security_parameters.bulk_cipher_algorithm, + HashSz = SP#security_parameters.hash_size, + CipherS0 = CS0#connection_state.cipher_state, + case ssl_cipher:decipher(BCA, HashSz, CipherS0, Fragment, Version) of + {T, Mac, CipherS1} -> + CS1 = CS0#connection_state{cipher_state = CipherS1}, + TLength = size(T), + MacHash = hash_with_seqno(CS1, Type, Version, Epoch, SeqNo, TLength, T), + case ssl_record:is_correct_mac(Mac, MacHash) of + true -> + {TLS#ssl_tls{fragment = T}, CS1}; + false -> + ?ALERT_REC(?FATAL, ?BAD_RECORD_MAC) + end; + #alert{} = Alert -> + Alert + end. + +hash_with_seqno(#connection_state{mac_secret = MacSecret, + security_parameters = + SecPars}, + Type, Version = {254, _}, + Epoch, SeqNo, Length, Fragment) -> + mac_hash(Version, + SecPars#security_parameters.mac_algorithm, + MacSecret, (Epoch bsl 48) + SeqNo, Type, + Length, Fragment). + +hash_and_bump_seqno(#connection_state{epoch = Epoch, + sequence_number = SeqNo, + mac_secret = MacSecret, + security_parameters = + SecPars} = CS0, + Type, Version = {254, _}, Length, Fragment) -> + Hash = mac_hash(Version, + SecPars#security_parameters.mac_algorithm, + MacSecret, (Epoch bsl 48) + SeqNo, Type, + Length, Fragment), + {Hash, CS0#connection_state{sequence_number = SeqNo+1}}. + +mac_hash(Version, MacAlg, MacSecret, SeqNo, Type, Length, Fragment) -> + dtls_v1:mac_hash(MacAlg, MacSecret, SeqNo, Type, Version, + Length, Fragment). |