%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2007-2015. 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: Help funtions for handling the TLS (specific parts of)
%%% SSL/TLS/DTLS handshake protocol
%%----------------------------------------------------------------------
-module(tls_handshake).
-include("tls_handshake.hrl").
-include("tls_record.hrl").
-include("ssl_alert.hrl").
-include("ssl_internal.hrl").
-include("ssl_cipher.hrl").
-include_lib("public_key/include/public_key.hrl").
-export([client_hello/8, hello/4,
get_tls_handshake/3, encode_handshake/2, decode_handshake/3]).
-type tls_handshake() :: #client_hello{} | ssl_handshake:ssl_handshake().
%%====================================================================
%% 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,
#ssl_options{versions = Versions,
ciphers = UserSuites,
fallback = Fallback
} = SslOpts,
Cache, CacheCb, Renegotiation, OwnCert) ->
Version = tls_record:highest_protocol_version(Versions),
Pending = ssl_record:pending_connection_state(ConnectionStates, read),
SecParams = Pending#connection_state.security_parameters,
AvailableCipherSuites = ssl_handshake:available_suites(UserSuites, Version),
Extensions = ssl_handshake:client_hello_extensions(Host, Version,
AvailableCipherSuites,
SslOpts, ConnectionStates, Renegotiation),
CipherSuites =
case Fallback of
true ->
[?TLS_FALLBACK_SCSV | ssl_handshake:cipher_suites(AvailableCipherSuites, Renegotiation)];
false ->
ssl_handshake:cipher_suites(AvailableCipherSuites, Renegotiation)
end,
Id = ssl_session:client_id({Host, Port, SslOpts}, Cache, CacheCb, OwnCert),
#client_hello{session_id = Id,
client_version = Version,
cipher_suites = CipherSuites,
compression_methods = ssl_record:compressions(),
random = SecParams#security_parameters.client_random,
extensions = Extensions
}.
%%--------------------------------------------------------------------
-spec hello(#server_hello{} | #client_hello{}, #ssl_options{},
#connection_states{} | {inet:port_number(), #session{}, db_handle(),
atom(), #connection_states{}, binary() | undefined},
boolean()) ->
{tls_record:tls_version(), session_id(), #connection_states{}, binary() | undefined}|
{tls_record:tls_version(), {resumed | new, #session{}}, #connection_states{},
[binary()] | undefined,
[ssl_handshake:oid()] | undefined, [ssl_handshake:oid()] | undefined} |
#alert{}.
%%
%% Description: Handles a recieved hello message
%%--------------------------------------------------------------------
hello(#server_hello{server_version = Version, random = Random,
cipher_suite = CipherSuite,
compression_method = Compression,
session_id = SessionId, extensions = HelloExt},
#ssl_options{versions = SupportedVersions} = SslOpt,
ConnectionStates0, Renegotiation) ->
case tls_record:is_acceptable_version(Version, SupportedVersions) of
true ->
handle_server_hello_extensions(Version, SessionId, Random, CipherSuite,
Compression, HelloExt, SslOpt, ConnectionStates0, Renegotiation);
false ->
?ALERT_REC(?FATAL, ?PROTOCOL_VERSION)
end;
hello(#client_hello{client_version = ClientVersion,
cipher_suites = CipherSuites} = Hello,
#ssl_options{versions = Versions} = SslOpts,
Info, Renegotiation) ->
Version = ssl_handshake:select_version(tls_record, ClientVersion, Versions),
case ssl_cipher:is_fallback(CipherSuites) of
true ->
Highest = tls_record:highest_protocol_version(Versions),
case tls_record:is_higher(Highest, Version) of
true ->
?ALERT_REC(?FATAL, ?INAPPROPRIATE_FALLBACK);
false ->
handle_client_hello(Version, Hello, SslOpts, Info, Renegotiation)
end;
false ->
handle_client_hello(Version, Hello, SslOpts, Info, Renegotiation)
end.
%%--------------------------------------------------------------------
-spec encode_handshake(tls_handshake(), tls_record:tls_version()) -> iolist().
%%
%% Description: Encode a handshake packet
%%--------------------------------------------------------------------x
encode_handshake(Package, Version) ->
{MsgType, Bin} = enc_handshake(Package, Version),
Len = byte_size(Bin),
[MsgType, ?uint24(Len), Bin].
%%--------------------------------------------------------------------
-spec get_tls_handshake(tls_record:tls_version(), binary(), binary() | iolist()) ->
{[tls_handshake()], binary()}.
%%
%% Description: Given buffered and new data from ssl_record, collects
%% and returns it as a list of handshake messages, also returns leftover
%% data.
%%--------------------------------------------------------------------
get_tls_handshake(Version, Data, <<>>) ->
get_tls_handshake_aux(Version, Data, []);
get_tls_handshake(Version, Data, Buffer) ->
get_tls_handshake_aux(Version, list_to_binary([Buffer, Data]), []).
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
handle_client_hello(Version, #client_hello{session_id = SugesstedId,
cipher_suites = CipherSuites,
compression_methods = Compressions,
random = Random,
extensions = #hello_extensions{elliptic_curves = Curves} = HelloExt},
#ssl_options{versions = Versions} = SslOpts,
{Port, Session0, Cache, CacheCb, ConnectionStates0, Cert}, Renegotiation) ->
case tls_record:is_acceptable_version(Version, Versions) of
true ->
ECCCurve = ssl_handshake:select_curve(Curves, ssl_handshake:supported_ecc(Version)),
{Type, #session{cipher_suite = CipherSuite} = Session1}
= ssl_handshake:select_session(SugesstedId, CipherSuites, Compressions,
Port, Session0#session{ecc = ECCCurve}, Version,
SslOpts, Cache, CacheCb, Cert),
case CipherSuite of
no_suite ->
?ALERT_REC(?FATAL, ?INSUFFICIENT_SECURITY);
_ ->
handle_client_hello_extensions(Version, Type, Random, CipherSuites, HelloExt,
SslOpts, Session1, ConnectionStates0,
Renegotiation)
end;
false ->
?ALERT_REC(?FATAL, ?PROTOCOL_VERSION)
end.
get_tls_handshake_aux(Version, <<?BYTE(Type), ?UINT24(Length),
Body:Length/binary,Rest/binary>>, Acc) ->
Raw = <<?BYTE(Type), ?UINT24(Length), Body/binary>>,
Handshake = decode_handshake(Version, Type, Body),
get_tls_handshake_aux(Version, Rest, [{Handshake,Raw} | Acc]);
get_tls_handshake_aux(_Version, Data, Acc) ->
{lists:reverse(Acc), Data}.
decode_handshake(_, ?HELLO_REQUEST, <<>>) ->
#hello_request{};
%% Client hello v2.
%% 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.
decode_handshake(_Version, ?CLIENT_HELLO, <<?BYTE(Major), ?BYTE(Minor),
?UINT16(CSLength), ?UINT16(0),
?UINT16(CDLength),
CipherSuites:CSLength/binary,
ChallengeData:CDLength/binary>>) ->
#client_hello{client_version = {Major, Minor},
random = ssl_v2:client_random(ChallengeData, CDLength),
session_id = 0,
cipher_suites = ssl_handshake:decode_suites('3_bytes', CipherSuites),
compression_methods = [?NULL],
extensions = #hello_extensions{}
};
decode_handshake(_Version, ?CLIENT_HELLO, <<?BYTE(Major), ?BYTE(Minor), Random:32/binary,
?BYTE(SID_length), Session_ID:SID_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({client, Extensions}),
#client_hello{
client_version = {Major,Minor},
random = Random,
session_id = Session_ID,
cipher_suites = ssl_handshake:decode_suites('2_bytes', CipherSuites),
compression_methods = Comp_methods,
extensions = DecodedExtensions
};
decode_handshake(Version, Tag, Msg) ->
ssl_handshake:decode_handshake(Version, Tag, Msg).
enc_handshake(#hello_request{}, _Version) ->
{?HELLO_REQUEST, <<>>};
enc_handshake(#client_hello{client_version = {Major, Minor},
random = Random,
session_id = SessionID,
cipher_suites = CipherSuites,
compression_methods = CompMethods,
extensions = HelloExtensions}, _Version) ->
SIDLength = byte_size(SessionID),
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,
?UINT16(CsLength), BinCipherSuites/binary,
?BYTE(CmLength), BinCompMethods/binary, ExtensionsBin/binary>>};
enc_handshake(HandshakeMsg, Version) ->
ssl_handshake:encode_handshake(HandshakeMsg, Version).
handle_client_hello_extensions(Version, Type, Random, CipherSuites,
HelloExt, SslOpts, Session0, ConnectionStates0, Renegotiation) ->
try ssl_handshake:handle_client_hello_extensions(tls_record, Random, CipherSuites,
HelloExt, Version, SslOpts,
Session0, ConnectionStates0, Renegotiation) of
{Session, ConnectionStates, ServerHelloExt} ->
{Version, {Type, Session}, ConnectionStates, ServerHelloExt}
catch throw:Alert ->
Alert
end.
handle_server_hello_extensions(Version, SessionId, Random, CipherSuite,
Compression, HelloExt, SslOpt, ConnectionStates0, Renegotiation) ->
case ssl_handshake:handle_server_hello_extensions(tls_record, Random, CipherSuite,
Compression, HelloExt, Version,
SslOpt, ConnectionStates0, Renegotiation) of
#alert{} = Alert ->
Alert;
{ConnectionStates, Protocol} ->
{Version, SessionId, ConnectionStates, Protocol}
end.
