Merge remote-tracking branch 'upstream/maint'

1 files changed, 1037 insertions, 0 deletions

diff --git a/lib/ssl/src/tls.erl b/lib/ssl/src/tls.erl
new file mode 100644
index 0000000000..fcecf8196f
--- /dev/null
+++ b/lib/ssl/src/tls.erl
@@ -0,0 +1,1037 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1999-2013. 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%
+%%
+
+%%
+
+%%% Purpose : Main API module for SSL.
+
+-module(tls).
+
+-export([start/0, start/1, stop/0, transport_accept/1,
+	 transport_accept/2, ssl_accept/1, ssl_accept/2, ssl_accept/3,
+	 cipher_suites/0, cipher_suites/1, suite_definition/1,
+	 close/1, shutdown/2,
+	 connect/3, connect/2, connect/4, connection_info/1,
+	 controlling_process/2, listen/2, peername/1, peercert/1,
+	 recv/2, recv/3, send/2, getopts/2, setopts/2, sockname/1,
+	 versions/0, session_info/1, format_error/1,
+	 renegotiate/1, prf/5, clear_pem_cache/0, random_bytes/1, negotiated_next_protocol/1]).
+
+-include("ssl_internal.hrl").
+-include("ssl_record.hrl").
+-include("ssl_cipher.hrl").
+-include("ssl_handshake.hrl").
+-include("ssl_srp.hrl").
+
+-include_lib("public_key/include/public_key.hrl"). 
+
+%% Visible in API
+-export_type([connect_option/0, listen_option/0, ssl_option/0, transport_option/0,
+	      erl_cipher_suite/0, %% From ssl_cipher.hrl 
+	      tls_atom_version/0, %% From ssl_internal.hrl
+	      prf_random/0, sslsocket/0]).
+
+-record(config, {ssl,               %% SSL parameters
+		 inet_user,         %% User set inet options
+		 emulated,          %% #socket_option{} emulated
+		 inet_ssl,          %% inet options for internal ssl socket 
+		 cb                 %% Callback info
+		}).
+
+-type sslsocket()                :: #sslsocket{}.
+-type connect_option()           :: socket_connect_option() | ssl_option() | transport_option().
+-type socket_connect_option()    :: gen_tcp:connect_option().
+-type listen_option()            :: socket_listen_option() | ssl_option() | transport_option().
+-type socket_listen_option()     :: gen_tcp:listen_option().
+
+-type ssl_option()    :: {verify, verify_type()} |
+			{verify_fun, {fun(), InitialUserState::term()}} |
+                        {fail_if_no_peer_cert, boolean()} | {depth, integer()} |
+                        {cert, Der::binary()} | {certfile, path()} | {key, Der::binary()} |
+                        {keyfile, path()} | {password, string()} | {cacerts, [Der::binary()]} |
+                        {cacertfile, path()} | {dh, Der::binary()} | {dhfile, path()} |
+                        {user_lookup_fun, {fun(), InitialUserState::term()}} |
+                        {psk_identity, string()} |
+                        {srp_identity, {string(), string()}} |
+                        {ciphers, ciphers()} | {ssl_imp, ssl_imp()} | {reuse_sessions, boolean()} |
+                        {reuse_session, fun()} | {hibernate_after, integer()|undefined} |
+                        {next_protocols_advertised, list(binary())} |
+                        {client_preferred_next_protocols, binary(), client | server, list(binary())}.
+
+-type verify_type()  :: verify_none | verify_peer.
+-type path()         :: string().
+-type ciphers()      :: [erl_cipher_suite()] |
+			string(). % (according to old API)
+-type ssl_imp()      :: new | old.
+
+-type transport_option() :: {cb_info, {CallbackModule::atom(), DataTag::atom(), 
+				       ClosedTag::atom(), ErrTag::atom()}}.
+-type prf_random() :: client_random | server_random.
+
+%%--------------------------------------------------------------------
+-spec start() -> ok  | {error, reason()}.
+-spec start(permanent | transient | temporary) -> ok | {error, reason()}.
+%%
+%% Description: Utility function that starts the ssl, 
+%% crypto and public_key applications. Default type
+%% is temporary. see application(3)
+%%--------------------------------------------------------------------
+start() ->
+    application:start(crypto),
+    application:start(public_key),
+    application:start(ssl).
+
+start(Type) ->
+    application:start(crypto, Type),
+    application:start(public_key, Type),
+    application:start(ssl, Type).
+
+%%--------------------------------------------------------------------
+-spec stop() -> ok.
+%%
+%% Description: Stops the ssl application.
+%%--------------------------------------------------------------------
+stop() ->
+    application:stop(ssl).
+
+%%--------------------------------------------------------------------
+-spec connect(host() | port(), [connect_option()]) -> {ok, #sslsocket{}} |
+					      {error, reason()}.
+-spec connect(host() | port(), [connect_option()] | inet:port_number(), 
+	      timeout() | list()) ->
+		     {ok, #sslsocket{}} | {error, reason()}.
+-spec connect(host() | port(), inet:port_number(), list(), timeout()) ->
+		     {ok, #sslsocket{}} | {error, reason()}.
+
+%%
+%% Description: Connect to an ssl server.
+%%--------------------------------------------------------------------
+connect(Socket, SslOptions) when is_port(Socket) ->
+    connect(Socket, SslOptions, infinity).
+
+connect(Socket, SslOptions0, Timeout) when is_port(Socket) ->
+    {Transport,_,_,_} = proplists:get_value(cb_info, SslOptions0, 
+					      {gen_tcp, tcp, tcp_closed, tcp_error}),    
+    EmulatedOptions = emulated_options(),
+    {ok, SocketValues} = ssl_socket:getopts(Transport, Socket, EmulatedOptions),
+    try handle_options(SslOptions0 ++ SocketValues, client) of
+	{ok, #config{cb = CbInfo, ssl = SslOptions, emulated = EmOpts}} ->
+	   
+	    ok = ssl_socket:setopts(Transport, Socket, internal_inet_values()),
+	    case ssl_socket:peername(Transport, Socket) of
+		{ok, {Address, Port}} ->
+		    tls_connection:connect(Address, Port, Socket, 
+					   {SslOptions, EmOpts},
+					   self(), CbInfo, Timeout);
+		{error, Error} ->
+		    {error, Error}
+	    end
+    catch 
+	_:{error, Reason} ->
+            {error, Reason}
+    end;
+
+connect(Host, Port, Options) ->
+    connect(Host, Port, Options, infinity).
+
+connect(Host, Port, Options, Timeout) ->
+    try handle_options(Options, client) of
+	{ok, Config} ->
+	    do_connect(Host,Port,Config,Timeout)
+    catch
+	throw:Error ->
+	    Error
+    end.
+
+%%--------------------------------------------------------------------
+-spec listen(inet:port_number(), [listen_option()]) ->{ok, #sslsocket{}} | {error, reason()}.
+		    
+%%
+%% Description: Creates an ssl listen socket.
+%%--------------------------------------------------------------------
+listen(_Port, []) ->
+    {error, nooptions};
+listen(Port, Options0) ->
+    try
+	{ok, Config} = handle_options(Options0, server),
+	#config{cb = {Transport, _, _, _}, inet_user = Options} = Config,
+	case Transport:listen(Port, Options) of
+	    {ok, ListenSocket} ->
+		{ok, #sslsocket{pid = {ListenSocket, Config}}};
+	    Err = {error, _} ->
+		Err
+	end
+    catch
+	Error = {error, _} ->
+	    Error
+    end.
+%%--------------------------------------------------------------------
+-spec transport_accept(#sslsocket{}) -> {ok, #sslsocket{}} |
+					{error, reason()}.
+-spec transport_accept(#sslsocket{}, timeout()) -> {ok, #sslsocket{}} |
+						   {error, reason()}.
+%%
+%% Description: Performs transport accept on an ssl listen socket
+%%--------------------------------------------------------------------
+transport_accept(ListenSocket) ->
+    transport_accept(ListenSocket, infinity).
+
+transport_accept(#sslsocket{pid = {ListenSocket, #config{cb = CbInfo, ssl = SslOpts}}}, Timeout) ->
+    
+    %% The setopt could have been invoked on the listen socket
+    %% and options should be inherited.
+    EmOptions = emulated_options(),
+    {Transport,_,_, _} = CbInfo,    
+    {ok, SocketValues} = ssl_socket:getopts(Transport, ListenSocket, EmOptions),
+    ok = ssl_socket:setopts(Transport, ListenSocket, internal_inet_values()),
+    case Transport:accept(ListenSocket, Timeout) of
+	{ok, Socket} ->
+	    ok = ssl_socket:setopts(Transport, ListenSocket, SocketValues),
+	    {ok, Port} = ssl_socket:port(Transport, Socket),
+	    ConnArgs = [server, "localhost", Port, Socket,
+			{SslOpts, socket_options(SocketValues)}, self(), CbInfo],
+	    case ssl_connection_sup:start_child(ConnArgs) of
+		{ok, Pid} ->
+		    tls_connection:socket_control(Socket, Pid, Transport);
+		{error, Reason} ->
+		    {error, Reason}
+	    end;
+	{error, Reason} ->
+	    {error, Reason}
+    end.
+
+%%--------------------------------------------------------------------
+-spec ssl_accept(#sslsocket{}) -> ok | {error, reason()}.
+-spec ssl_accept(#sslsocket{} | port(), timeout()| [ssl_option() 
+						    | transport_option()]) ->
+			ok | {ok, #sslsocket{}} | {error, reason()}.
+-spec ssl_accept(port(), [ssl_option()| transport_option()], timeout()) -> 
+			{ok, #sslsocket{}} | {error, reason()}.
+%%
+%% Description: Performs accept on an ssl listen socket. e.i. performs
+%%              ssl handshake. 
+%%--------------------------------------------------------------------
+ssl_accept(ListenSocket) ->
+    ssl_accept(ListenSocket, infinity).
+
+ssl_accept(#sslsocket{} = Socket, Timeout) ->
+    tls_connection:handshake(Socket, Timeout);
+    
+ssl_accept(ListenSocket, SslOptions)  when is_port(ListenSocket) -> 
+    ssl_accept(ListenSocket, SslOptions, infinity).
+
+ssl_accept(Socket, SslOptions, Timeout) when is_port(Socket) -> 
+    {Transport,_,_,_} = 
+	proplists:get_value(cb_info, SslOptions, {gen_tcp, tcp, tcp_closed, tcp_error}),    
+    EmulatedOptions = emulated_options(),
+    {ok, SocketValues} = ssl_socket:getopts(Transport, Socket, EmulatedOptions),
+    try handle_options(SslOptions ++ SocketValues, server) of
+	{ok, #config{cb = CbInfo, ssl = SslOpts, emulated = EmOpts}} ->
+	    ok = ssl_socket:setopts(Transport, Socket, internal_inet_values()),
+	    {ok, Port} = ssl_socket:port(Transport, Socket),
+	    tls_connection:ssl_accept(Port, Socket,
+				      {SslOpts, EmOpts},
+				      self(), CbInfo, Timeout)
+    catch 
+	Error = {error, _Reason} -> Error
+    end.
+
+%%--------------------------------------------------------------------
+-spec  close(#sslsocket{}) -> term().
+%%
+%% Description: Close an ssl connection
+%%--------------------------------------------------------------------  
+close(#sslsocket{pid = Pid}) when is_pid(Pid) ->
+    tls_connection:close(Pid);
+close(#sslsocket{pid = {ListenSocket, #config{cb={Transport,_, _, _}}}}) ->
+    Transport:close(ListenSocket).
+
+%%--------------------------------------------------------------------
+-spec send(#sslsocket{}, iodata()) -> ok | {error, reason()}.
+%% 
+%% Description: Sends data over the ssl connection
+%%--------------------------------------------------------------------
+send(#sslsocket{pid = Pid}, Data) when is_pid(Pid) ->
+    tls_connection:send(Pid, Data);
+send(#sslsocket{pid = {ListenSocket, #config{cb={Transport, _, _, _}}}}, Data) ->
+    Transport:send(ListenSocket, Data). %% {error,enotconn}
+
+%%--------------------------------------------------------------------
+-spec recv(#sslsocket{}, integer()) -> {ok, binary()| list()} | {error, reason()}.
+-spec recv(#sslsocket{}, integer(), timeout()) -> {ok, binary()| list()} | {error, reason()}.
+%%
+%% Description: Receives data when active = false
+%%--------------------------------------------------------------------
+recv(Socket, Length) ->
+    recv(Socket, Length, infinity).
+recv(#sslsocket{pid = Pid}, Length, Timeout) when is_pid(Pid) ->
+    tls_connection:recv(Pid, Length, Timeout);
+recv(#sslsocket{pid = {Listen, 
+		       #config{cb={Transport, _, _, _}}}}, _,_) when is_port(Listen)->
+    Transport:recv(Listen, 0). %% {error,enotconn}
+
+%%--------------------------------------------------------------------
+-spec controlling_process(#sslsocket{}, pid()) -> ok | {error, reason()}.
+%%				 
+%% Description: Changes process that receives the messages when active = true
+%% or once. 
+%%--------------------------------------------------------------------
+controlling_process(#sslsocket{pid = Pid}, NewOwner) when is_pid(Pid), is_pid(NewOwner) ->
+    tls_connection:new_user(Pid, NewOwner);
+controlling_process(#sslsocket{pid = {Listen,
+				      #config{cb={Transport, _, _, _}}}}, 
+		    NewOwner) when is_port(Listen),
+				   is_pid(NewOwner) ->
+    Transport:controlling_process(Listen, NewOwner).
+
+%%--------------------------------------------------------------------
+-spec connection_info(#sslsocket{}) -> 	{ok, {tls_atom_version(), erl_cipher_suite()}} | 
+					{error, reason()}.
+%%
+%% Description: Returns ssl protocol and cipher used for the connection
+%%--------------------------------------------------------------------
+connection_info(#sslsocket{pid = Pid}) when is_pid(Pid) ->
+    tls_connection:info(Pid);
+connection_info(#sslsocket{pid = {Listen, _}}) when is_port(Listen) ->
+    {error, enotconn}.
+
+%%--------------------------------------------------------------------
+-spec peername(#sslsocket{}) -> {ok, {inet:ip_address(), inet:port_number()}} | {error, reason()}.
+%%
+%% Description: same as inet:peername/1.
+%%--------------------------------------------------------------------
+peername(#sslsocket{pid = Pid, fd = {Transport, Socket}}) when is_pid(Pid)->
+    ssl_socket:peername(Transport, Socket);
+peername(#sslsocket{pid = {ListenSocket,  #config{cb = {Transport,_,_,_}}}}) ->
+    ssl_socket:peername(Transport, ListenSocket). %% Will return {error, enotconn}
+
+%%--------------------------------------------------------------------
+-spec peercert(#sslsocket{}) ->{ok, DerCert::binary()} | {error, reason()}.
+%%
+%% Description: Returns the peercert.
+%%--------------------------------------------------------------------
+peercert(#sslsocket{pid = Pid}) when is_pid(Pid) ->
+    case tls_connection:peer_certificate(Pid) of
+	{ok, undefined} ->
+	    {error, no_peercert};
+        Result ->
+	    Result
+    end;
+peercert(#sslsocket{pid = {Listen, _}}) when is_port(Listen) ->
+    {error, enotconn}.
+
+%%--------------------------------------------------------------------
+-spec suite_definition(cipher_suite()) -> erl_cipher_suite().
+%%
+%% Description: Return erlang cipher suite definition.
+%%--------------------------------------------------------------------
+suite_definition(S) ->
+    {KeyExchange, Cipher, Hash, _} = ssl_cipher:suite_definition(S),
+    {KeyExchange, Cipher, Hash}.
+
+%%--------------------------------------------------------------------
+-spec negotiated_next_protocol(#sslsocket{}) -> {ok, binary()} | {error, reason()}.
+%%
+%% Description: Returns the next protocol that has been negotiated. If no
+%% protocol has been negotiated will return {error, next_protocol_not_negotiated}
+%%--------------------------------------------------------------------
+negotiated_next_protocol(#sslsocket{pid = Pid}) ->
+    tls_connection:negotiated_next_protocol(Pid).
+
+-spec cipher_suites() -> [erl_cipher_suite()].
+-spec cipher_suites(erlang | openssl | all) -> [erl_cipher_suite()] | [string()].
+			   
+%% Description: Returns all supported cipher suites.
+%%--------------------------------------------------------------------
+cipher_suites() ->
+    cipher_suites(erlang).
+  
+cipher_suites(erlang) ->
+    Version = tls_record:highest_protocol_version([]),
+    [suite_definition(S) || S <- ssl_cipher:suites(Version)];
+
+cipher_suites(openssl) ->
+    Version = tls_record:highest_protocol_version([]),
+    [ssl_cipher:openssl_suite_name(S) || S <- ssl_cipher:suites(Version)];
+cipher_suites(all) ->
+    Version = tls_record:highest_protocol_version([]),
+    Supported = ssl_cipher:suites(Version)
+	++ ssl_cipher:anonymous_suites()
+	++ ssl_cipher:psk_suites(Version)
+	++ ssl_cipher:srp_suites(),
+    [suite_definition(S) || S <- Supported].
+
+%%--------------------------------------------------------------------
+-spec getopts(#sslsocket{}, [gen_tcp:option_name()]) ->
+		     {ok, [gen_tcp:option()]} | {error, reason()}.
+%% 
+%% Description: Gets options
+%%--------------------------------------------------------------------
+getopts(#sslsocket{pid = Pid}, OptionTags) when is_pid(Pid), is_list(OptionTags) ->
+    tls_connection:get_opts(Pid, OptionTags);
+getopts(#sslsocket{pid = {ListenSocket,  #config{cb = {Transport,_,_,_}}}}, 
+	OptionTags) when is_list(OptionTags) ->
+    try ssl_socket:getopts(Transport, ListenSocket, OptionTags) of
+	{ok, _} = Result ->
+	    Result;
+	{error, InetError} ->
+	    {error, {options, {socket_options, OptionTags, InetError}}}
+    catch
+	_:_ ->
+	    {error, {options, {socket_options, OptionTags}}}
+    end;
+getopts(#sslsocket{}, OptionTags) ->
+    {error, {options, {socket_options, OptionTags}}}.
+
+%%--------------------------------------------------------------------
+-spec setopts(#sslsocket{},  [gen_tcp:option()]) -> ok | {error, reason()}.
+%% 
+%% Description: Sets options
+%%--------------------------------------------------------------------
+setopts(#sslsocket{pid = Pid}, Options0) when is_pid(Pid), is_list(Options0)  ->
+    try proplists:expand([{binary, [{mode, binary}]},
+			  {list, [{mode, list}]}], Options0) of
+	Options ->
+	    tls_connection:set_opts(Pid, Options)
+    catch
+	_:_ ->
+	    {error, {options, {not_a_proplist, Options0}}}
+    end;
+
+setopts(#sslsocket{pid = {ListenSocket, #config{cb = {Transport,_,_,_}}}}, Options) when is_list(Options) ->
+    try ssl_socket:setopts(Transport, ListenSocket, Options) of
+	ok ->
+	    ok;
+	{error, InetError} ->
+	    {error, {options, {socket_options, Options, InetError}}}
+    catch
+	_:Error ->
+	    {error, {options, {socket_options, Options, Error}}}
+    end;
+setopts(#sslsocket{}, Options) ->
+    {error, {options,{not_a_proplist, Options}}}.
+
+%%---------------------------------------------------------------
+-spec shutdown(#sslsocket{}, read | write | read_write) ->  ok | {error, reason()}.
+%%		      
+%% Description: Same as gen_tcp:shutdown/2
+%%--------------------------------------------------------------------
+shutdown(#sslsocket{pid = {Listen, #config{cb={Transport,_, _, _}}}},
+	 How) when is_port(Listen) ->
+    Transport:shutdown(Listen, How);
+shutdown(#sslsocket{pid = Pid}, How) ->
+    tls_connection:shutdown(Pid, How).
+
+%%--------------------------------------------------------------------
+-spec sockname(#sslsocket{}) -> {ok, {inet:ip_address(), inet:port_number()}} | {error, reason()}.
+%%		     
+%% Description: Same as inet:sockname/1
+%%--------------------------------------------------------------------
+sockname(#sslsocket{pid = {Listen,  #config{cb={Transport,_, _, _}}}}) when is_port(Listen) ->
+    ssl_socket:sockname(Transport, Listen);
+
+sockname(#sslsocket{pid = Pid, fd = {Transport, Socket}}) when is_pid(Pid) ->
+    ssl_socket:sockname(Transport, Socket).
+
+%%---------------------------------------------------------------
+-spec session_info(#sslsocket{}) -> {ok, list()} | {error, reason()}.
+%% 
+%% Description: Returns list of session info currently [{session_id, session_id(),
+%% {cipher_suite, cipher_suite()}]
+%%--------------------------------------------------------------------
+session_info(#sslsocket{pid = Pid}) when is_pid(Pid) ->
+    tls_connection:session_info(Pid);
+session_info(#sslsocket{pid = {Listen,_}}) when is_port(Listen) ->
+    {error, enotconn}.
+
+%%---------------------------------------------------------------
+-spec versions() -> [{ssl_app, string()} | {supported, [tls_atom_version()]} | 
+		     {available, [tls_atom_version()]}].
+%%
+%% Description: Returns a list of relevant versions.
+%%--------------------------------------------------------------------
+versions() ->
+    Vsns = tls_record:supported_protocol_versions(),
+    SupportedVsns = [tls_record:protocol_version(Vsn) || Vsn <- Vsns],
+    AvailableVsns = ?ALL_SUPPORTED_VERSIONS,
+    [{ssl_app, ?VSN}, {supported, SupportedVsns}, {available, AvailableVsns}].
+
+
+%%---------------------------------------------------------------
+-spec renegotiate(#sslsocket{}) -> ok | {error, reason()}.
+%% 
+%% Description: Initiates a renegotiation.
+%%--------------------------------------------------------------------
+renegotiate(#sslsocket{pid = Pid}) when is_pid(Pid) ->
+    tls_connection:renegotiation(Pid);
+renegotiate(#sslsocket{pid = {Listen,_}}) when is_port(Listen) ->
+    {error, enotconn}.
+
+%%--------------------------------------------------------------------
+-spec prf(#sslsocket{}, binary() | 'master_secret', binary(),
+	  binary() | prf_random(), non_neg_integer()) ->
+		 {ok, binary()} | {error, reason()}.
+%%
+%% Description: use a ssl sessions TLS PRF to generate key material
+%%--------------------------------------------------------------------
+prf(#sslsocket{pid = Pid},
+    Secret, Label, Seed, WantedLength) when is_pid(Pid) ->
+    tls_connection:prf(Pid, Secret, Label, Seed, WantedLength);
+prf(#sslsocket{pid = {Listen,_}}, _,_,_,_) when is_port(Listen) ->
+    {error, enotconn}.
+
+%%--------------------------------------------------------------------
+-spec clear_pem_cache() -> ok.
+%%
+%% Description: Clear the PEM cache
+%%--------------------------------------------------------------------
+clear_pem_cache() ->
+    ssl_manager:clear_pem_cache().
+
+%%---------------------------------------------------------------
+-spec format_error({error, term()}) -> list().
+%%
+%% Description: Creates error string.
+%%--------------------------------------------------------------------
+format_error({error, Reason}) ->
+    format_error(Reason);
+format_error(Reason) when is_list(Reason) ->
+    Reason;
+format_error(closed) ->
+    "TLS connection is closed";
+format_error({tls_alert, Description}) ->
+    "TLS Alert: " ++ Description;
+format_error({options,{FileType, File, Reason}}) when FileType == cacertfile;
+						      FileType == certfile;
+						      FileType == keyfile;
+						      FileType == dhfile ->
+    Error = file_error_format(Reason),
+    file_desc(FileType) ++ File ++ ": " ++ Error;
+format_error({options, {socket_options, Option, Error}}) ->
+    lists:flatten(io_lib:format("Invalid transport socket option ~p: ~s", [Option, format_error(Error)]));
+format_error({options, {socket_options, Option}}) ->
+    lists:flatten(io_lib:format("Invalid socket option: ~p", [Option]));
+format_error({options, Options}) ->
+    lists:flatten(io_lib:format("Invalid TLS option: ~p", [Options]));
+
+format_error(Error) ->
+    case inet:format_error(Error) of
+        "unknown POSIX" ++ _ ->
+            unexpected_format(Error);
+        Other ->
+            Other
+    end.
+
+%%--------------------------------------------------------------------
+-spec random_bytes(integer()) -> binary().
+
+%%
+%% Description: Generates cryptographically secure random sequence if possible
+%% fallbacks on pseudo random function
+%%--------------------------------------------------------------------
+random_bytes(N) ->
+    try crypto:strong_rand_bytes(N) of
+	RandBytes ->
+	    RandBytes
+    catch
+	error:low_entropy ->
+	    crypto:rand_bytes(N)
+    end.
+
+%%%--------------------------------------------------------------
+%%% Internal functions
+%%%--------------------------------------------------------------------
+do_connect(Address, Port,
+	       #config{cb=CbInfo, inet_user=UserOpts, ssl=SslOpts,
+		       emulated=EmOpts,inet_ssl=SocketOpts},
+	       Timeout) ->
+    {Transport, _, _, _} = CbInfo,    
+    try Transport:connect(Address, Port,  SocketOpts, Timeout) of
+	{ok, Socket} ->
+	    tls_connection:connect(Address, Port, Socket, {SslOpts,EmOpts},
+				   self(), CbInfo, Timeout);
+	{error, Reason} ->
+	    {error, Reason}
+    catch
+	exit:{function_clause, _} ->
+	    {error, {options, {cb_info, CbInfo}}};
+	exit:badarg ->
+	    {error, {options, {socket_options, UserOpts}}};
+	exit:{badarg, _} ->
+	    {error, {options, {socket_options, UserOpts}}}
+    end.
+
+handle_options(Opts0, _Role) ->
+    Opts = proplists:expand([{binary, [{mode, binary}]},
+			     {list, [{mode, list}]}], Opts0),
+    ReuseSessionFun = fun(_, _, _, _) -> true end,
+
+    DefaultVerifyNoneFun =
+	{fun(_,{bad_cert, _}, UserState) ->
+		 {valid, UserState};
+	    (_,{extension, _}, UserState) ->
+		 {unknown, UserState};
+	    (_, valid, UserState) ->
+		 {valid, UserState};
+	    (_, valid_peer, UserState) ->
+		 {valid, UserState}
+	 end, []},
+
+    VerifyNoneFun = handle_option(verify_fun, Opts, DefaultVerifyNoneFun),
+
+    UserFailIfNoPeerCert = handle_option(fail_if_no_peer_cert, Opts, false),
+    UserVerifyFun = handle_option(verify_fun, Opts, undefined),
+    CaCerts = handle_option(cacerts, Opts, undefined),
+
+    {Verify, FailIfNoPeerCert, CaCertDefault, VerifyFun} =
+	%% Handle 0, 1, 2 for backwards compatibility
+	case proplists:get_value(verify, Opts, verify_none) of
+	    0 ->
+		{verify_none, false,
+		 ca_cert_default(verify_none, VerifyNoneFun, CaCerts), VerifyNoneFun};
+	    1  ->
+		{verify_peer, false,
+		 ca_cert_default(verify_peer, UserVerifyFun, CaCerts), UserVerifyFun};
+	    2 ->
+		{verify_peer, true,
+		 ca_cert_default(verify_peer, UserVerifyFun, CaCerts), UserVerifyFun};
+	    verify_none ->
+		{verify_none, false,
+		 ca_cert_default(verify_none, VerifyNoneFun, CaCerts), VerifyNoneFun};
+	    verify_peer ->
+		{verify_peer, UserFailIfNoPeerCert,
+		 ca_cert_default(verify_peer, UserVerifyFun, CaCerts), UserVerifyFun};
+	    Value ->
+		throw({error, {options, {verify, Value}}})
+	end,
+
+    CertFile = handle_option(certfile, Opts, <<>>),
+    
+    Versions = case handle_option(versions, Opts, []) of
+		   [] ->
+		       tls_record:supported_protocol_versions();  
+		   Vsns  ->
+		       [tls_record:protocol_version(Vsn) || Vsn <- Vsns]
+	       end,  
+
+    SSLOptions = #ssl_options{
+      versions   = Versions,
+      verify     = validate_option(verify, Verify),
+      verify_fun = VerifyFun,
+      fail_if_no_peer_cert = FailIfNoPeerCert,
+      verify_client_once =  handle_option(verify_client_once, Opts, false),
+      depth      = handle_option(depth,  Opts, 1),
+      cert       = handle_option(cert, Opts, undefined),
+      certfile   = CertFile,
+      key        = handle_option(key, Opts, undefined),
+      keyfile    = handle_option(keyfile,  Opts, CertFile),
+      password   = handle_option(password, Opts, ""),
+      cacerts    = CaCerts,
+      cacertfile = handle_option(cacertfile, Opts, CaCertDefault),
+      dh         = handle_option(dh, Opts, undefined),
+      dhfile     = handle_option(dhfile, Opts, undefined),
+      user_lookup_fun = handle_option(user_lookup_fun, Opts, undefined),
+      psk_identity = handle_option(psk_identity, Opts, undefined),
+      srp_identity = handle_option(srp_identity, Opts, undefined),
+      ciphers    = handle_option(ciphers, Opts, []),
+      %% Server side option
+      reuse_session = handle_option(reuse_session, Opts, ReuseSessionFun),
+      reuse_sessions = handle_option(reuse_sessions, Opts, true),
+      secure_renegotiate = handle_option(secure_renegotiate, Opts, false),
+      renegotiate_at = handle_option(renegotiate_at, Opts, ?DEFAULT_RENEGOTIATE_AT),
+      hibernate_after = handle_option(hibernate_after, Opts, undefined),
+      erl_dist = handle_option(erl_dist, Opts, false),
+      next_protocols_advertised = 
+			handle_option(next_protocols_advertised, Opts, undefined),
+      next_protocol_selector = 
+			make_next_protocol_selector(
+			  handle_option(client_preferred_next_protocols, Opts, undefined))
+     },
+
+    CbInfo  = proplists:get_value(cb_info, Opts, {gen_tcp, tcp, tcp_closed, tcp_error}),    
+    SslOptions = [versions, verify, verify_fun,
+		  fail_if_no_peer_cert, verify_client_once,
+		  depth, cert, certfile, key, keyfile,
+		  password, cacerts, cacertfile, dh, dhfile, 
+		  user_lookup_fun, psk_identity, srp_identity, ciphers,
+		  reuse_session, reuse_sessions, ssl_imp,
+		  cb_info, renegotiate_at, secure_renegotiate, hibernate_after, 
+		  erl_dist, next_protocols_advertised,
+		  client_preferred_next_protocols],
+    
+    SockOpts = lists:foldl(fun(Key, PropList) -> 
+				   proplists:delete(Key, PropList)
+			   end, Opts, SslOptions),
+    
+    {SSLsock, Emulated} = emulated_options(SockOpts),
+    {ok, #config{ssl=SSLOptions, emulated=Emulated, inet_ssl=SSLsock,
+		 inet_user=SockOpts, cb=CbInfo}}.
+
+handle_option(OptionName, Opts, Default) ->
+    validate_option(OptionName, 
+		    proplists:get_value(OptionName, Opts, Default)).
+
+
+validate_option(versions, Versions)  ->
+    validate_versions(Versions, Versions);
+validate_option(verify, Value) 
+  when Value == verify_none; Value == verify_peer ->
+    Value;
+validate_option(verify_fun, undefined)  ->
+    undefined;
+%% Backwards compatibility
+validate_option(verify_fun, Fun) when is_function(Fun) ->
+    {fun(_,{bad_cert, _} = Reason, OldFun) ->
+	     case OldFun([Reason]) of
+		 true ->
+		     {valid, OldFun};
+		 false ->
+		     {fail, Reason}
+	     end;
+	(_,{extension, _}, UserState) ->
+	     {unknown, UserState};
+	(_, valid, UserState) ->
+	     {valid, UserState};
+	(_, valid_peer, UserState) ->
+	     {valid, UserState}
+     end, Fun};
+validate_option(verify_fun, {Fun, _} = Value) when is_function(Fun) ->
+   Value;
+validate_option(fail_if_no_peer_cert, Value) 
+  when Value == true; Value == false ->
+    Value;
+validate_option(verify_client_once, Value) 
+  when Value == true; Value == false ->
+    Value;
+validate_option(depth, Value) when is_integer(Value), 
+                                   Value >= 0, Value =< 255->
+    Value;
+validate_option(cert, Value) when Value == undefined;
+                                 is_binary(Value) ->
+    Value;
+validate_option(certfile, undefined = Value) ->
+    Value;
+validate_option(certfile, Value) when is_binary(Value) ->
+    Value;
+validate_option(certfile, Value) when is_list(Value) ->
+    list_to_binary(Value);
+
+validate_option(key, undefined) ->
+    undefined;
+validate_option(key, {KeyType, Value}) when is_binary(Value),
+					    KeyType == rsa; %% Backwards compatibility
+					    KeyType == dsa; %% Backwards compatibility
+					    KeyType == 'RSAPrivateKey';
+					    KeyType == 'DSAPrivateKey';
+					    KeyType == 'PrivateKeyInfo' ->
+    {KeyType, Value};
+
+validate_option(keyfile, undefined) ->
+   <<>>;
+validate_option(keyfile, Value) when is_binary(Value) ->
+    Value;
+validate_option(keyfile, Value) when is_list(Value), Value =/= "" ->
+    list_to_binary(Value);
+validate_option(password, Value) when is_list(Value) ->
+    Value;
+
+validate_option(cacerts, Value) when Value == undefined;
+				     is_list(Value) ->
+    Value;
+%% certfile must be present in some cases otherwhise it can be set
+%% to the empty string.
+validate_option(cacertfile, undefined) ->
+   <<>>;
+validate_option(cacertfile, Value) when is_binary(Value) ->
+    Value;
+validate_option(cacertfile, Value) when is_list(Value), Value =/= ""->
+    list_to_binary(Value);
+validate_option(dh, Value) when Value == undefined;
+				is_binary(Value) ->
+    Value;
+validate_option(dhfile, undefined = Value)  ->
+    Value;
+validate_option(dhfile, Value) when is_binary(Value) ->
+    Value;
+validate_option(dhfile, Value) when is_list(Value), Value =/= "" ->
+    list_to_binary(Value);
+validate_option(psk_identity, undefined) ->
+    undefined;
+validate_option(psk_identity, Identity)
+  when is_list(Identity), Identity =/= "", length(Identity) =< 65535 ->
+    list_to_binary(Identity);
+validate_option(user_lookup_fun, undefined) ->
+    undefined;
+validate_option(user_lookup_fun, {Fun, _} = Value) when is_function(Fun, 3) ->
+   Value;
+validate_option(srp_identity, undefined) ->
+    undefined;
+validate_option(srp_identity, {Username, Password})
+  when is_list(Username), is_list(Password), Username =/= "", length(Username) =< 255 ->
+    {list_to_binary(Username), list_to_binary(Password)};
+
+validate_option(ciphers, Value)  when is_list(Value) ->
+    Version = tls_record:highest_protocol_version([]),
+    try cipher_suites(Version, Value)
+    catch
+	exit:_ ->
+	    throw({error, {options, {ciphers, Value}}});
+	error:_->
+	    throw({error, {options, {ciphers, Value}}})
+    end;
+validate_option(reuse_session, Value) when is_function(Value) ->
+    Value;
+validate_option(reuse_sessions, Value) when Value == true; 
+					    Value == false ->
+    Value;
+
+validate_option(secure_renegotiate, Value) when Value == true; 
+						Value == false ->
+    Value;
+validate_option(renegotiate_at, Value) when is_integer(Value) ->
+    erlang:min(Value, ?DEFAULT_RENEGOTIATE_AT);
+
+validate_option(hibernate_after, undefined) ->
+    undefined;
+validate_option(hibernate_after, Value) when is_integer(Value), Value >= 0 ->
+    Value;
+validate_option(erl_dist,Value) when Value == true;
+				     Value == false ->
+    Value;
+validate_option(client_preferred_next_protocols = Opt, {Precedence, PreferredProtocols} = Value)
+  when is_list(PreferredProtocols) ->
+    case tls_record:highest_protocol_version([]) of
+	{3,0} ->
+	    throw({error, {options, {not_supported_in_sslv3, {Opt, Value}}}});
+	_ ->
+	    validate_binary_list(client_preferred_next_protocols, PreferredProtocols),
+	    validate_npn_ordering(Precedence),
+	    {Precedence, PreferredProtocols, ?NO_PROTOCOL}
+    end;
+validate_option(client_preferred_next_protocols = Opt, {Precedence, PreferredProtocols, Default} = Value)
+      when is_list(PreferredProtocols), is_binary(Default),
+           byte_size(Default) > 0, byte_size(Default) < 256 ->
+    case tls_record:highest_protocol_version([]) of
+	{3,0} ->
+	    throw({error, {options, {not_supported_in_sslv3, {Opt, Value}}}});
+	_ ->
+	    validate_binary_list(client_preferred_next_protocols, PreferredProtocols),
+	    validate_npn_ordering(Precedence),
+	    Value
+    end;
+	
+validate_option(client_preferred_next_protocols, undefined) ->
+    undefined;
+validate_option(next_protocols_advertised = Opt, Value) when is_list(Value) ->
+    case tls_record:highest_protocol_version([]) of
+	{3,0} ->
+	    throw({error, {options, {not_supported_in_sslv3, {Opt, Value}}}});
+	_ ->
+	    validate_binary_list(next_protocols_advertised, Value),
+	    Value
+    end;
+
+validate_option(next_protocols_advertised, undefined) ->
+    undefined;
+validate_option(Opt, Value) ->
+    throw({error, {options, {Opt, Value}}}).
+
+validate_npn_ordering(client) ->
+    ok;
+validate_npn_ordering(server) ->
+    ok;
+validate_npn_ordering(Value) ->
+    throw({error, {options, {client_preferred_next_protocols, {invalid_precedence, Value}}}}).
+
+validate_binary_list(Opt, List) ->
+    lists:foreach(
+        fun(Bin) when is_binary(Bin),
+                      byte_size(Bin) > 0,
+                      byte_size(Bin) < 256 ->
+            ok;
+           (Bin) ->
+            throw({error, {options, {Opt, {invalid_protocol, Bin}}}})
+        end, List).
+
+validate_versions([], Versions) ->
+    Versions;
+validate_versions([Version | Rest], Versions) when Version == 'tlsv1.2';
+                                                   Version == 'tlsv1.1';
+                                                   Version == tlsv1; 
+                                                   Version == sslv3 ->
+    validate_versions(Rest, Versions);					   
+validate_versions([Ver| _], Versions) ->
+    throw({error, {options, {Ver, {versions, Versions}}}}).
+
+validate_inet_option(mode, Value)
+  when Value =/= list, Value =/= binary ->
+    throw({error, {options, {mode,Value}}});
+validate_inet_option(packet, Value)
+  when not (is_atom(Value) orelse is_integer(Value)) ->
+    throw({error, {options, {packet,Value}}});
+validate_inet_option(packet_size, Value)
+  when not is_integer(Value) ->
+    throw({error, {options, {packet_size,Value}}});
+validate_inet_option(header, Value)
+  when not is_integer(Value) ->
+    throw({error, {options, {header,Value}}});
+validate_inet_option(active, Value)
+  when Value =/= true, Value =/= false, Value =/= once ->
+    throw({error, {options, {active,Value}}});
+validate_inet_option(_, _) ->
+    ok.
+
+%% The option cacerts overrides cacertsfile
+ca_cert_default(_,_, [_|_]) ->
+    undefined;
+ca_cert_default(verify_none, _, _) ->
+    undefined;
+ca_cert_default(verify_peer, {Fun,_}, _) when is_function(Fun) ->
+    undefined;
+%% Server that wants to verify_peer and has no verify_fun must have
+%% some trusted certs.
+ca_cert_default(verify_peer, undefined, _) ->
+    "".
+
+emulated_options() ->
+    [mode, packet, active, header, packet_size].
+
+internal_inet_values() ->
+    [{packet_size,0},{packet, 0},{header, 0},{active, false},{mode,binary}].
+
+socket_options(InetValues) ->
+    #socket_options{
+		mode   = proplists:get_value(mode, InetValues, lists),
+		header = proplists:get_value(header, InetValues, 0),
+		active = proplists:get_value(active, InetValues, active),
+		packet = proplists:get_value(packet, InetValues, 0),
+		packet_size = proplists:get_value(packet_size, InetValues)	     
+	       }.
+
+emulated_options(Opts) ->
+    emulated_options(Opts, internal_inet_values(), #socket_options{}).
+
+emulated_options([{mode,Opt}|Opts], Inet, Emulated) ->
+    validate_inet_option(mode,Opt),
+    emulated_options(Opts, Inet, Emulated#socket_options{mode=Opt});
+emulated_options([{header,Opt}|Opts], Inet, Emulated) ->
+    validate_inet_option(header,Opt),
+    emulated_options(Opts, Inet, Emulated#socket_options{header=Opt});
+emulated_options([{active,Opt}|Opts], Inet, Emulated) ->
+    validate_inet_option(active,Opt),
+    emulated_options(Opts, Inet, Emulated#socket_options{active=Opt});
+emulated_options([{packet,Opt}|Opts], Inet, Emulated) ->
+    validate_inet_option(packet,Opt),
+    emulated_options(Opts, Inet, Emulated#socket_options{packet=Opt});
+emulated_options([{packet_size,Opt}|Opts], Inet, Emulated) ->
+    validate_inet_option(packet_size,Opt),
+    emulated_options(Opts, Inet, Emulated#socket_options{packet_size=Opt});
+emulated_options([Opt|Opts], Inet, Emulated) ->
+    emulated_options(Opts, [Opt|Inet], Emulated);
+emulated_options([], Inet,Emulated) ->
+    {Inet, Emulated}.
+
+cipher_suites(Version, []) ->
+    ssl_cipher:suites(Version);
+cipher_suites(Version, [{_,_,_,_}| _] = Ciphers0) -> %% Backwards compatibility
+    Ciphers = [{KeyExchange, Cipher, Hash} || {KeyExchange, Cipher, Hash, _} <- Ciphers0],
+    cipher_suites(Version, Ciphers);
+cipher_suites(Version, [{_,_,_}| _] = Ciphers0) ->
+    Ciphers = [ssl_cipher:suite(C) || C <- Ciphers0],
+    cipher_suites(Version, Ciphers);
+
+cipher_suites(Version, [Cipher0 | _] = Ciphers0) when is_binary(Cipher0) ->
+    Supported0 = ssl_cipher:suites(Version)  
+	++ ssl_cipher:anonymous_suites() 
+	++ ssl_cipher:psk_suites(Version)
+	++ ssl_cipher:srp_suites(),
+    Supported = ssl_cipher:filter_suites(Supported0),
+    case [Cipher || Cipher <- Ciphers0, lists:member(Cipher, Supported)] of
+	[] ->
+	    Supported;
+	Ciphers ->
+	    Ciphers
+    end;
+cipher_suites(Version, [Head | _] = Ciphers0) when is_list(Head) ->
+    %% Format: ["RC4-SHA","RC4-MD5"]
+    Ciphers = [ssl_cipher:openssl_suite(C) || C <- Ciphers0],
+    cipher_suites(Version, Ciphers); 
+cipher_suites(Version, Ciphers0)  ->
+    %% Format: "RC4-SHA:RC4-MD5"
+    Ciphers = [ssl_cipher:openssl_suite(C) || C <- string:tokens(Ciphers0, ":")],
+    cipher_suites(Version, Ciphers).
+
+unexpected_format(Error) ->    
+    lists:flatten(io_lib:format("Unexpected error: ~p", [Error])).
+
+file_error_format({error, Error})->
+    case file:format_error(Error) of 
+	"unknown POSIX error" ->
+	    "decoding error";
+	Str ->
+	    Str
+    end;
+file_error_format(_) ->
+    "decoding error".
+    
+file_desc(cacertfile) ->
+    "Invalid CA certificate file ";
+file_desc(certfile) ->
+    "Invalid certificate file ";
+file_desc(keyfile) ->
+    "Invalid key file "; 
+file_desc(dhfile) ->
+    "Invalid DH params file ".
+
+detect(_Pred, []) ->
+    undefined;
+detect(Pred, [H|T]) ->
+    case Pred(H) of
+        true ->
+            H;
+        _ ->
+            detect(Pred, T)
+    end.
+
+make_next_protocol_selector(undefined) ->
+    undefined;
+make_next_protocol_selector({client, AllProtocols, DefaultProtocol}) ->
+    fun(AdvertisedProtocols) ->
+        case detect(fun(PreferredProtocol) -> 
+			    lists:member(PreferredProtocol, AdvertisedProtocols) 
+		    end, AllProtocols) of
+            undefined -> 
+		DefaultProtocol;
+            PreferredProtocol -> 
+		PreferredProtocol
+        end
+    end;
+
+make_next_protocol_selector({server, AllProtocols, DefaultProtocol}) ->
+    fun(AdvertisedProtocols) ->
+	    case detect(fun(PreferredProtocol) -> 
+				lists:member(PreferredProtocol, AllProtocols) 
+			end, 
+			AdvertisedProtocols) of
+		undefined -> 
+		    DefaultProtocol;
+            PreferredProtocol -> 
+		    PreferredProtocol
+	    end
+    end.