%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2013-2015. 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%
%%
-module(dtls_connection).
%% Internal application API
-behaviour(gen_fsm).
-include("dtls_connection.hrl").
-include("dtls_handshake.hrl").
-include("ssl_alert.hrl").
-include("dtls_record.hrl").
-include("ssl_cipher.hrl").
-include("ssl_api.hrl").
-include("ssl_internal.hrl").
-include("ssl_srp.hrl").
-include_lib("public_key/include/public_key.hrl").
%% Internal application API
%% Setup
-export([start_fsm/8]).
%% State transition handling
-export([next_record/1, next_state/4%,
%%next_state_connection/2
]).
%% Handshake handling
-export([%%renegotiate/1,
send_handshake/2, send_change_cipher/2]).
%% Alert and close handling
-export([send_alert/2, handle_own_alert/4, %%handle_close_alert/3,
handle_normal_shutdown/3
%%handle_unexpected_message/3,
%%alert_user/5, alert_user/8
]).
%% Data handling
-export([%%write_application_data/3,
read_application_data/2%%,
%% passive_receive/2, next_record_if_active/1
]).
%% Called by tls_connection_sup
-export([start_link/7]).
%% gen_fsm callbacks
-export([init/1, hello/2, certify/2, cipher/2,
abbreviated/2, connection/2, handle_event/3,
handle_sync_event/4, handle_info/3, terminate/3, code_change/4]).
%%====================================================================
%% Internal application API
%%====================================================================
start_fsm(Role, Host, Port, Socket, {#ssl_options{erl_dist = false},_} = Opts,
User, {CbModule, _,_, _} = CbInfo,
Timeout) ->
try
{ok, Pid} = dtls_connection_sup:start_child([Role, Host, Port, Socket,
Opts, User, CbInfo]),
{ok, SslSocket} = ssl_connection:socket_control(?MODULE, Socket, Pid, CbModule),
ok = ssl_connection:handshake(SslSocket, Timeout),
{ok, SslSocket}
catch
error:{badmatch, {error, _} = Error} ->
Error
end;
start_fsm(Role, Host, Port, Socket, {#ssl_options{erl_dist = true},_} = Opts,
User, {CbModule, _,_, _} = CbInfo,
Timeout) ->
try
{ok, Pid} = dtls_connection_sup:start_child_dist([Role, Host, Port, Socket,
Opts, User, CbInfo]),
{ok, SslSocket} = ssl_connection:socket_control(?MODULE, Socket, Pid, CbModule),
ok = ssl_connection:handshake(SslSocket, Timeout),
{ok, SslSocket}
catch
error:{badmatch, {error, _} = Error} ->
Error
end.
send_handshake(Handshake, #state{negotiated_version = Version,
tls_handshake_history = Hist0,
connection_states = ConnectionStates0} = State0) ->
{BinHandshake, ConnectionStates, Hist} =
encode_handshake(Handshake, Version, ConnectionStates0, Hist0),
send_flight(BinHandshake, State0#state{connection_states = ConnectionStates,
tls_handshake_history = Hist
}).
send_alert(Alert, #state{negotiated_version = Version,
socket = Socket,
transport_cb = Transport,
connection_states = ConnectionStates0} = State0) ->
{BinMsg, ConnectionStates} =
ssl_alert:encode(Alert, Version, ConnectionStates0),
Transport:send(Socket, BinMsg),
State0#state{connection_states = ConnectionStates}.
send_change_cipher(Msg, #state{connection_states = ConnectionStates0,
socket = Socket,
negotiated_version = Version,
transport_cb = Transport} = State0) ->
{BinChangeCipher, ConnectionStates} =
encode_change_cipher(Msg, Version, ConnectionStates0),
Transport:send(Socket, BinChangeCipher),
State0#state{connection_states = ConnectionStates}.
%%====================================================================
%% tls_connection_sup API
%%====================================================================
%%--------------------------------------------------------------------
-spec start_link(atom(), host(), inet:port_number(), port(), list(), pid(), tuple()) ->
{ok, pid()} | ignore | {error, reason()}.
%%
%% Description: Creates a gen_fsm process which calls Module:init/1 to
%% initialize. To ensure a synchronized start-up procedure, this function
%% does not return until Module:init/1 has returned.
%%--------------------------------------------------------------------
start_link(Role, Host, Port, Socket, Options, User, CbInfo) ->
{ok, proc_lib:spawn_link(?MODULE, init, [[Role, Host, Port, Socket, Options, User, CbInfo]])}.
init([Role, Host, Port, Socket, {SSLOpts0, _} = Options, User, CbInfo]) ->
process_flag(trap_exit, true),
State0 = initial_state(Role, Host, Port, Socket, Options, User, CbInfo),
Handshake = ssl_handshake:init_handshake_history(),
TimeStamp = calendar:datetime_to_gregorian_seconds({date(), time()}),
try ssl_config:init(SSLOpts0, Role) of
{ok, Ref, CertDbHandle, FileRefHandle, CacheHandle, CRLDbInfo, OwnCert, Key, DHParams} ->
Session = State0#state.session,
State = State0#state{
tls_handshake_history = Handshake,
session = Session#session{own_certificate = OwnCert,
time_stamp = TimeStamp},
file_ref_db = FileRefHandle,
cert_db_ref = Ref,
cert_db = CertDbHandle,
crl_db = CRLDbInfo,
session_cache = CacheHandle,
private_key = Key,
diffie_hellman_params = DHParams},
gen_fsm:enter_loop(?MODULE, [], hello, State, get_timeout(State))
catch
throw:Error ->
gen_fsm:enter_loop(?MODULE, [], error, {Error,State0}, get_timeout(State0))
end.
%%--------------------------------------------------------------------
%% Description:There should be one instance of this function for each
%% possible state name. Whenever a gen_fsm receives an event sent
%% using gen_fsm:send_event/2, the instance of this function with the
%% same name as the current state name StateName is called to handle
%% the event. It is also called if a timeout occurs.
%%
hello(start, #state{host = Host, port = Port, role = client,
ssl_options = SslOpts,
session = #session{own_certificate = Cert} = Session0,
session_cache = Cache, session_cache_cb = CacheCb,
transport_cb = Transport, socket = Socket,
connection_states = ConnectionStates0,
renegotiation = {Renegotiation, _}} = State0) ->
Hello = dtls_handshake:client_hello(Host, Port, ConnectionStates0, SslOpts,
Cache, CacheCb, Renegotiation, Cert),
Version = Hello#client_hello.client_version,
Handshake0 = ssl_handshake:init_handshake_history(),
{BinMsg, ConnectionStates, Handshake} =
encode_handshake(Hello, Version, ConnectionStates0, Handshake0),
Transport:send(Socket, BinMsg),
State1 = State0#state{connection_states = ConnectionStates,
negotiated_version = Version, %% Requested version
session =
Session0#session{session_id = Hello#client_hello.session_id},
tls_handshake_history = Handshake},
{Record, State} = next_record(State1),
next_state(hello, hello, Record, State);
hello(Hello = #client_hello{client_version = ClientVersion,
extensions = #hello_extensions{hash_signs = HashSigns}},
State = #state{connection_states = ConnectionStates0,
port = Port, session = #session{own_certificate = Cert} = Session0,
renegotiation = {Renegotiation, _},
session_cache = Cache,
session_cache_cb = CacheCb,
ssl_options = SslOpts}) ->
case dtls_handshake:hello(Hello, SslOpts, {Port, Session0, Cache, CacheCb,
ConnectionStates0, Cert}, Renegotiation) of
{Version, {Type, Session},
ConnectionStates,
#hello_extensions{ec_point_formats = EcPointFormats,
elliptic_curves = EllipticCurves} = ServerHelloExt} ->
HashSign = ssl_handshake:select_hashsign(HashSigns, Cert,
dtls_v1:corresponding_tls_version(Version)),
ssl_connection:hello({common_client_hello, Type, ServerHelloExt, HashSign},
State#state{connection_states = ConnectionStates,
negotiated_version = Version,
session = Session,
client_ecc = {EllipticCurves, EcPointFormats}}, ?MODULE);
#alert{} = Alert ->
handle_own_alert(Alert, ClientVersion, hello, State)
end;
hello(Hello,
#state{connection_states = ConnectionStates0,
negotiated_version = ReqVersion,
role = client,
renegotiation = {Renegotiation, _},
ssl_options = SslOptions} = State) ->
case dtls_handshake:hello(Hello, SslOptions, ConnectionStates0, Renegotiation) of
#alert{} = Alert ->
handle_own_alert(Alert, ReqVersion, hello, State);
{Version, NewId, ConnectionStates, ProtoExt, Protocol} ->
ssl_connection:handle_session(Hello,
Version, NewId, ConnectionStates, ProtoExt, Protocol, State)
end;
hello(Msg, State) ->
ssl_connection:hello(Msg, State, ?MODULE).
abbreviated(Msg, State) ->
ssl_connection:abbreviated(Msg, State, ?MODULE).
certify(Msg, State) ->
ssl_connection:certify(Msg, State, ?MODULE).
cipher(Msg, State) ->
ssl_connection:cipher(Msg, State, ?MODULE).
connection(#hello_request{}, #state{host = Host, port = Port,
session = #session{own_certificate = Cert} = Session0,
session_cache = Cache, session_cache_cb = CacheCb,
ssl_options = SslOpts,
connection_states = ConnectionStates0,
renegotiation = {Renegotiation, _}} = State0) ->
Hello = dtls_handshake:client_hello(Host, Port, ConnectionStates0, SslOpts,
Cache, CacheCb, Renegotiation, Cert),
%% TODO DTLS version State1 = send_handshake(Hello, State0),
State1 = State0,
{Record, State} =
next_record(
State1#state{session = Session0#session{session_id
= Hello#client_hello.session_id}}),
next_state(connection, hello, Record, State);
connection(#client_hello{} = Hello, #state{role = server, allow_renegotiate = true} = State) ->
%% Mitigate Computational DoS attack
%% http://www.educatedguesswork.org/2011/10/ssltls_and_computational_dos.html
%% http://www.thc.org/thc-ssl-dos/ Rather than disabling client
%% initiated renegotiation we will disallow many client initiated
%% renegotiations immediately after each other.
erlang:send_after(?WAIT_TO_ALLOW_RENEGOTIATION, self(), allow_renegotiate),
hello(Hello, State#state{allow_renegotiate = false});
connection(#client_hello{}, #state{role = server, allow_renegotiate = false} = State0) ->
Alert = ?ALERT_REC(?WARNING, ?NO_RENEGOTIATION),
State = send_alert(Alert, State0),
next_state_connection(connection, State);
connection(Msg, State) ->
ssl_connection:connection(Msg, State, tls_connection).
%%--------------------------------------------------------------------
%% Description: Whenever a gen_fsm receives an event sent using
%% gen_fsm:send_all_state_event/2, this function is called to handle
%% the event. Not currently used!
%%--------------------------------------------------------------------
handle_event(_Event, StateName, State) ->
{next_state, StateName, State, get_timeout(State)}.
%%--------------------------------------------------------------------
%% Description: Whenever a gen_fsm receives an event sent using
%% gen_fsm:sync_send_all_state_event/2,3, this function is called to handle
%% the event.
%%--------------------------------------------------------------------
handle_sync_event(Event, From, StateName, State) ->
ssl_connection:handle_sync_event(Event, From, StateName, State).
%%--------------------------------------------------------------------
%% Description: This function is called by a gen_fsm when it receives any
%% other message than a synchronous or asynchronous event
%% (or a system message).
%%--------------------------------------------------------------------
%% raw data from socket, unpack records
handle_info({Protocol, _, Data}, StateName,
#state{data_tag = Protocol} = State0) ->
%% Simplify for now to avoid dialzer warnings before implementation is compleate
%% case next_tls_record(Data, State0) of
%% {Record, State} ->
%% next_state(StateName, StateName, Record, State);
%% #alert{} = Alert ->
%% handle_normal_shutdown(Alert, StateName, State0),
%% {stop, {shutdown, own_alert}, State0}
%% end;
{Record, State} = next_tls_record(Data, State0),
next_state(StateName, StateName, Record, State);
handle_info({CloseTag, Socket}, StateName,
#state{socket = Socket, close_tag = CloseTag,
negotiated_version = _Version} = State) ->
handle_normal_shutdown(?ALERT_REC(?FATAL, ?CLOSE_NOTIFY), StateName, State),
{stop, {shutdown, transport_closed}, State};
handle_info(Msg, StateName, State) ->
ssl_connection:handle_info(Msg, StateName, State).
%%--------------------------------------------------------------------
%% Description:This function is called by a gen_fsm when it is about
%% to terminate. It should be the opposite of Module:init/1 and do any
%% necessary cleaning up. When it returns, the gen_fsm terminates with
%% Reason. The return value is ignored.
%%--------------------------------------------------------------------
terminate(Reason, StateName, State) ->
ssl_connection:terminate(Reason, StateName, State).
%%--------------------------------------------------------------------
%% code_change(OldVsn, StateName, State, Extra) -> {ok, StateName, NewState}
%% Description: Convert process state when code is changed
%%--------------------------------------------------------------------
code_change(_OldVsn, StateName, State, _Extra) ->
{ok, StateName, State}.
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
encode_handshake(Handshake, Version, ConnectionStates0, Hist0) ->
Seq = sequence(ConnectionStates0),
{EncHandshake, FragmentedHandshake} = dtls_handshake:encode_handshake(Handshake, Version,
Seq),
Hist = ssl_handshake:update_handshake_history(Hist0, EncHandshake),
{Encoded, ConnectionStates} =
dtls_record:encode_handshake(FragmentedHandshake,
Version, ConnectionStates0),
{Encoded, ConnectionStates, Hist}.
next_record(#state{%%flight = #flight{state = finished},
protocol_buffers =
#protocol_buffers{dtls_packets = [], dtls_cipher_texts = [CT | Rest]}
= Buffers,
connection_states = ConnStates0} = State) ->
case dtls_record:decode_cipher_text(CT, ConnStates0) of
{Plain, ConnStates} ->
{Plain, State#state{protocol_buffers =
Buffers#protocol_buffers{dtls_cipher_texts = Rest},
connection_states = ConnStates}};
#alert{} = Alert ->
{Alert, State}
end;
next_record(#state{socket = Socket,
transport_cb = Transport} = State) -> %% when FlightState =/= finished
ssl_socket:setopts(Transport, Socket, [{active,once}]),
{no_record, State};
next_record(State) ->
{no_record, State}.
next_state(Current,_, #alert{} = Alert, #state{negotiated_version = Version} = State) ->
handle_own_alert(Alert, Version, Current, State);
next_state(_,Next, no_record, State) ->
{next_state, Next, State, get_timeout(State)};
%% next_state(_,Next, #ssl_tls{type = ?ALERT, fragment = EncAlerts}, State) ->
%% Alerts = decode_alerts(EncAlerts),
%% handle_alerts(Alerts, {next_state, Next, State, get_timeout(State)});
next_state(Current, Next, #ssl_tls{type = ?HANDSHAKE, fragment = Data},
State0 = #state{protocol_buffers =
#protocol_buffers{dtls_handshake_buffer = Buf0} = Buffers,
negotiated_version = Version}) ->
Handle =
fun({#hello_request{} = Packet, _}, {next_state, connection = SName, State}) ->
%% This message should not be included in handshake
%% message hashes. Starts new handshake (renegotiation)
Hs0 = ssl_handshake:init_handshake_history(),
?MODULE:SName(Packet, State#state{tls_handshake_history=Hs0,
renegotiation = {true, peer}});
({#hello_request{} = Packet, _}, {next_state, SName, State}) ->
%% This message should not be included in handshake
%% message hashes. Already in negotiation so it will be ignored!
?MODULE:SName(Packet, State);
({#client_hello{} = Packet, Raw}, {next_state, connection = SName, State}) ->
Version = Packet#client_hello.client_version,
Hs0 = ssl_handshake:init_handshake_history(),
Hs1 = ssl_handshake:update_handshake_history(Hs0, Raw),
?MODULE:SName(Packet, State#state{tls_handshake_history=Hs1,
renegotiation = {true, peer}});
({Packet, Raw}, {next_state, SName, State = #state{tls_handshake_history=Hs0}}) ->
Hs1 = ssl_handshake:update_handshake_history(Hs0, Raw),
?MODULE:SName(Packet, State#state{tls_handshake_history=Hs1});
(_, StopState) -> StopState
end,
try
{Packets, Buf} = tls_handshake:get_tls_handshake(Version,Data,Buf0),
State = State0#state{protocol_buffers =
Buffers#protocol_buffers{dtls_packets = Packets,
dtls_handshake_buffer = Buf}},
handle_dtls_handshake(Handle, Next, State)
catch throw:#alert{} = Alert ->
handle_own_alert(Alert, Version, Current, State0)
end;
next_state(_, StateName, #ssl_tls{type = ?APPLICATION_DATA, fragment = Data}, State0) ->
%% Simplify for now to avoid dialzer warnings before implementation is compleate
%% case read_application_data(Data, State0) of
%% Stop = {stop,_,_} ->
%% Stop;
%% {Record, State} ->
%% next_state(StateName, StateName, Record, State)
%% end;
{Record, State} = read_application_data(Data, State0),
next_state(StateName, StateName, Record, State);
next_state(Current, Next, #ssl_tls{type = ?CHANGE_CIPHER_SPEC, fragment = <<1>>} =
_ChangeCipher,
#state{connection_states = ConnectionStates0} = State0) ->
ConnectionStates1 =
ssl_record:activate_pending_connection_state(ConnectionStates0, read),
{Record, State} = next_record(State0#state{connection_states = ConnectionStates1}),
next_state(Current, Next, Record, State);
next_state(Current, Next, #ssl_tls{type = _Unknown}, State0) ->
%% Ignore unknown type
{Record, State} = next_record(State0),
next_state(Current, Next, Record, State).
handle_dtls_handshake(Handle, StateName,
#state{protocol_buffers =
#protocol_buffers{dtls_packets = [Packet]} = Buffers} = State) ->
FsmReturn = {next_state, StateName, State#state{protocol_buffers =
Buffers#protocol_buffers{dtls_packets = []}}},
Handle(Packet, FsmReturn);
handle_dtls_handshake(Handle, StateName,
#state{protocol_buffers =
#protocol_buffers{dtls_packets = [Packet | Packets]} = Buffers} =
State0) ->
FsmReturn = {next_state, StateName, State0#state{protocol_buffers =
Buffers#protocol_buffers{dtls_packets =
Packets}}},
case Handle(Packet, FsmReturn) of
{next_state, NextStateName, State, _Timeout} ->
handle_dtls_handshake(Handle, NextStateName, State);
{stop, _,_} = Stop ->
Stop
end.
send_flight(Fragments, #state{transport_cb = Transport, socket = Socket,
protocol_buffers = _PBuffers} = State) ->
Transport:send(Socket, Fragments),
%% Start retransmission
%% State#state{protocol_buffers =
%% (PBuffers#protocol_buffers){ #flight{state = waiting}}}}.
State.
handle_own_alert(_,_,_, State) -> %% Place holder
{stop, {shutdown, own_alert}, State}.
handle_normal_shutdown(_, _, _State) -> %% Place holder
ok.
encode_change_cipher(#change_cipher_spec{}, Version, ConnectionStates) ->
dtls_record:encode_change_cipher_spec(Version, ConnectionStates).
initial_state(Role, Host, Port, Socket, {SSLOptions, SocketOptions}, User,
{CbModule, DataTag, CloseTag, ErrorTag}) ->
ConnectionStates = ssl_record:init_connection_states(Role),
SessionCacheCb = case application:get_env(ssl, session_cb) of
{ok, Cb} when is_atom(Cb) ->
Cb;
_ ->
ssl_session_cache
end,
Monitor = erlang:monitor(process, User),
#state{socket_options = SocketOptions,
%% We do not want to save the password in the state so that
%% could be written in the clear into error logs.
ssl_options = SSLOptions#ssl_options{password = undefined},
session = #session{is_resumable = new},
transport_cb = CbModule,
data_tag = DataTag,
close_tag = CloseTag,
error_tag = ErrorTag,
role = Role,
host = Host,
port = Port,
socket = Socket,
connection_states = ConnectionStates,
protocol_buffers = #protocol_buffers{},
user_application = {Monitor, User},
user_data_buffer = <<>>,
session_cache_cb = SessionCacheCb,
renegotiation = {false, first},
start_or_recv_from = undefined,
send_queue = queue:new(),
protocol_cb = ?MODULE
}.
read_application_data(_,State) ->
{#ssl_tls{fragment = <<"place holder">>}, State}.
next_tls_record(_, State) ->
{#ssl_tls{fragment = <<"place holder">>}, State}.
get_timeout(_) -> %% Place holder
infinity.
next_state_connection(_, State) -> %% Place holder
{next_state, connection, State, get_timeout(State)}.
sequence(_) ->
%%TODO real imp
1.
