Merge branch 'essen/ssl-alpn'

* essen/ssl-alpn:
  ssl: Add TLS-ALPN support

OTP-12580

13 files changed, 202 insertions, 65 deletions

diff --git a/lib/ssl/src/dtls_connection.erl b/lib/ssl/src/dtls_connection.erl
index f177a8610d..610e2c4e41 100644
--- a/lib/ssl/src/dtls_connection.erl
+++ b/lib/ssl/src/dtls_connection.erl
@@ -228,9 +228,9 @@ hello(Hello,
     case dtls_handshake:hello(Hello, SslOptions, ConnectionStates0, Renegotiation) of
 	#alert{} = Alert ->
 	    handle_own_alert(Alert, ReqVersion, hello, State);
-	{Version, NewId, ConnectionStates, NextProtocol} ->
+	{Version, NewId, ConnectionStates, ProtoExt, Protocol} ->
 	    ssl_connection:handle_session(Hello, 
-					  Version, NewId, ConnectionStates, NextProtocol, State)
+					  Version, NewId, ConnectionStates, ProtoExt, Protocol, State)
     end;
 
 hello(Msg, State) ->
diff --git a/lib/ssl/src/dtls_handshake.erl b/lib/ssl/src/dtls_handshake.erl
index 31d525b295..30381df050 100644
--- a/lib/ssl/src/dtls_handshake.erl
+++ b/lib/ssl/src/dtls_handshake.erl
@@ -181,8 +181,8 @@ handle_server_hello_extensions(Version, SessionId, Random, CipherSuite,
 						      SslOpt, ConnectionStates0, Renegotiation) of
 	#alert{} = Alert ->
 	    Alert;
-	{ConnectionStates, Protocol} ->
-	    {Version, SessionId, ConnectionStates, Protocol}
+	{ConnectionStates, ProtoExt, Protocol} ->
+	    {Version, SessionId, ConnectionStates, ProtoExt, Protocol}
     end.
 
 dtls_fragment(Mss, MsgType, Len, MsgSeq, Bin, Offset, Acc)
diff --git a/lib/ssl/src/ssl.erl b/lib/ssl/src/ssl.erl
index 623fa92121..6461f64c1c 100644
--- a/lib/ssl/src/ssl.erl
+++ b/lib/ssl/src/ssl.erl
@@ -38,10 +38,12 @@
 %% SSL/TLS protocol handling
 -export([cipher_suites/0, cipher_suites/1, suite_definition/1,
 	 connection_info/1, versions/0, session_info/1, format_error/1,
-	 renegotiate/1, prf/5, negotiated_next_protocol/1]).
+	 renegotiate/1, prf/5, negotiated_protocol/1, negotiated_next_protocol/1]).
 %% Misc
 -export([random_bytes/1]).
 
+-deprecated({negotiated_next_protocol, 1, next_major_release}).
+
 -include("ssl_api.hrl").
 -include("ssl_internal.hrl").
 -include("ssl_record.hrl").
@@ -330,13 +332,27 @@ suite_definition(S) ->
     {KeyExchange, Cipher, Hash}.
 
 %%--------------------------------------------------------------------
+-spec negotiated_protocol(#sslsocket{}) -> {ok, binary()} | {error, reason()}.
+%%
+%% Description: Returns the protocol that has been negotiated. If no
+%% protocol has been negotiated will return {error, protocol_not_negotiated}
+%%--------------------------------------------------------------------
+negotiated_protocol(#sslsocket{pid = Pid}) ->
+    ssl_connection:negotiated_protocol(Pid).
+
+%%--------------------------------------------------------------------
 -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}) ->
-    ssl_connection:negotiated_next_protocol(Pid).
+negotiated_next_protocol(Socket) ->
+    case negotiated_protocol(Socket) of
+        {error, protocol_not_negotiated} ->
+            {error, next_protocol_not_negotiated};
+        Res ->
+            Res
+    end.
 
 %%--------------------------------------------------------------------
 -spec cipher_suites(erlang | openssl | all) -> [ssl_cipher:erl_cipher_suite()] |
@@ -644,6 +660,10 @@ handle_options(Opts0) ->
 		    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),
+		    alpn_advertised_protocols =
+			handle_option(alpn_advertised_protocols, Opts, undefined),
+		    alpn_preferred_protocols =
+			handle_option(alpn_preferred_protocols, Opts, undefined),
 		    next_protocols_advertised =
 			handle_option(next_protocols_advertised, Opts, undefined),
 		    next_protocol_selector =
@@ -667,7 +687,8 @@ handle_options(Opts0) ->
 		  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,
+		  erl_dist, alpn_advertised_protocols,
+		  alpn_preferred_protocols, next_protocols_advertised,
 		  client_preferred_next_protocols, log_alert,
 		  server_name_indication, honor_cipher_order, padding_check, crl_check, crl_cache,
 		  fallback],
@@ -803,6 +824,20 @@ validate_option(hibernate_after, Value) when is_integer(Value), Value >= 0 ->
     Value;
 validate_option(erl_dist,Value) when is_boolean(Value) ->
     Value;
+validate_option(Opt, Value)
+  when Opt =:= alpn_advertised_protocols orelse Opt =:= alpn_preferred_protocols,
+       is_list(Value) ->
+    case tls_record:highest_protocol_version([]) of
+	{3,0} ->
+	    throw({error, {options, {not_supported_in_sslv3, {Opt, Value}}}});
+	_ ->
+	    validate_binary_list(Opt, Value),
+	    Value
+    end;
+validate_option(Opt, Value)
+  when Opt =:= alpn_advertised_protocols orelse Opt =:= alpn_preferred_protocols,
+       Value =:= undefined ->
+    undefined;
 validate_option(client_preferred_next_protocols = Opt, {Precedence, PreferredProtocols} = Value)
   when is_list(PreferredProtocols) ->
     case tls_record:highest_protocol_version([]) of
@@ -1131,6 +1166,10 @@ new_ssl_options([{secure_renegotiate, Value} | Rest], #ssl_options{} = Opts, Rec
     new_ssl_options(Rest, Opts#ssl_options{secure_renegotiate = validate_option(secure_renegotiate, Value)}, RecordCB); 
 new_ssl_options([{hibernate_after, Value} | Rest], #ssl_options{} = Opts, RecordCB) -> 
     new_ssl_options(Rest, Opts#ssl_options{hibernate_after = validate_option(hibernate_after, Value)}, RecordCB);
+new_ssl_options([{alpn_advertised_protocols, Value} | Rest], #ssl_options{} = Opts, RecordCB) ->
+	new_ssl_options(Rest, Opts#ssl_options{alpn_advertised_protocols = validate_option(alpn_advertised_protocols, Value)}, RecordCB);
+new_ssl_options([{alpn_preferred_protocols, Value} | Rest], #ssl_options{} = Opts, RecordCB) ->
+	new_ssl_options(Rest, Opts#ssl_options{alpn_preferred_protocols = validate_option(alpn_preferred_protocols, Value)}, RecordCB);
 new_ssl_options([{next_protocols_advertised, Value} | Rest], #ssl_options{} = Opts, RecordCB) -> 
     new_ssl_options(Rest, Opts#ssl_options{next_protocols_advertised = validate_option(next_protocols_advertised, Value)}, RecordCB);
 new_ssl_options([{client_preferred_next_protocols, Value} | Rest], #ssl_options{} = Opts, RecordCB) -> 
diff --git a/lib/ssl/src/ssl_alert.erl b/lib/ssl/src/ssl_alert.erl
index 9e372f739a..c46facb75d 100644
--- a/lib/ssl/src/ssl_alert.erl
+++ b/lib/ssl/src/ssl_alert.erl
@@ -163,5 +163,7 @@ description_txt(?UNKNOWN_PSK_IDENTITY) ->
     "unknown psk identity";
 description_txt(?INAPPROPRIATE_FALLBACK) ->
     "inappropriate fallback";
+description_txt(?NO_APPLICATION_PROTOCOL) ->
+    "no application protocol";
 description_txt(Enum) ->
     lists:flatten(io_lib:format("unsupported/unknown alert: ~p", [Enum])).
diff --git a/lib/ssl/src/ssl_alert.hrl b/lib/ssl/src/ssl_alert.hrl
index a3619e4a35..70b7523975 100644
--- a/lib/ssl/src/ssl_alert.hrl
+++ b/lib/ssl/src/ssl_alert.hrl
@@ -69,6 +69,8 @@
 %%         bad_certificate_hash_value(114),      
 %% RFC 4366
 %%       unknown_psk_identity(115),
+%% RFC 7301
+%%       no_application_protocol(120),
 %%           (255)
 %%       } AlertDescription;
 
@@ -103,6 +105,7 @@
 -define(BAD_CERTIFICATE_STATUS_RESPONSE, 113).
 -define(BAD_CERTIFICATE_HASH_VALUE, 114).
 -define(UNKNOWN_PSK_IDENTITY, 115).
+-define(NO_APPLICATION_PROTOCOL, 120).
 
 -define(ALERT_REC(Level,Desc), #alert{level=Level,description=Desc,where={?FILE, ?LINE}}).
 
diff --git a/lib/ssl/src/ssl_api.hrl b/lib/ssl/src/ssl_api.hrl
index 22185ff60a..78127eeafa 100644
--- a/lib/ssl/src/ssl_api.hrl
+++ b/lib/ssl/src/ssl_api.hrl
@@ -49,6 +49,8 @@
                          {srp_identity, {string(), string()}} |
                          {ciphers, ciphers()} | {ssl_imp, ssl_imp()} | {reuse_sessions, boolean()} |
                          {reuse_session, fun()} | {hibernate_after, integer()|undefined} |
+                         {alpn_advertised_protocols, [binary()]} |
+                         {alpn_preferred_protocols, [binary()]} |
                          {next_protocols_advertised, list(binary())} |
                          {client_preferred_next_protocols, binary(), client | server, list(binary())}.
 
diff --git a/lib/ssl/src/ssl_connection.erl b/lib/ssl/src/ssl_connection.erl
index 08d0145aa7..4a839872a6 100644
--- a/lib/ssl/src/ssl_connection.erl
+++ b/lib/ssl/src/ssl_connection.erl
@@ -42,10 +42,10 @@
 %% User Events 
 -export([send/2, recv/3, close/1, shutdown/2,
 	 new_user/2, get_opts/2, set_opts/2, info/1, session_info/1, 
-	 peer_certificate/1, renegotiation/1, negotiated_next_protocol/1, prf/5	
+	 peer_certificate/1, renegotiation/1, negotiated_protocol/1, prf/5
 	]).
 
--export([handle_session/6]).
+-export([handle_session/7]).
 
 %% SSL FSM state functions 
 -export([hello/3, abbreviated/3, certify/3, cipher/3, connection/3]).
@@ -191,12 +191,12 @@ new_user(ConnectionPid, User) ->
     sync_send_all_state_event(ConnectionPid, {new_user, User}).
 
 %%--------------------------------------------------------------------
--spec negotiated_next_protocol(pid()) -> {ok, binary()} | {error, reason()}.
+-spec negotiated_protocol(pid()) -> {ok, binary()} | {error, reason()}.
 %%
 %% Description:  Returns the negotiated protocol
 %%--------------------------------------------------------------------
-negotiated_next_protocol(ConnectionPid) ->
-    sync_send_all_state_event(ConnectionPid, negotiated_next_protocol).
+negotiated_protocol(ConnectionPid) ->
+    sync_send_all_state_event(ConnectionPid, negotiated_protocol).
 
 %%--------------------------------------------------------------------
 -spec get_opts(pid(), list()) -> {ok, list()} | {error, reason()}.    
@@ -258,27 +258,26 @@ prf(ConnectionPid, Secret, Label, Seed, WantedLength) ->
 
 handle_session(#server_hello{cipher_suite = CipherSuite,
 			     compression_method = Compression}, 
-	       Version, NewId, ConnectionStates, NextProtocol, 
+	       Version, NewId, ConnectionStates, ProtoExt, Protocol0,
 	       #state{session = #session{session_id = OldId},
-		      negotiated_version = ReqVersion} = State0) ->
+		      negotiated_version = ReqVersion,
+			  negotiated_protocol = CurrentProtocol} = State0) ->
     {KeyAlgorithm, _, _, _} =
 	ssl_cipher:suite_definition(CipherSuite),
     
     PremasterSecret = make_premaster_secret(ReqVersion, KeyAlgorithm),
-    
-    NewNextProtocol = case NextProtocol of
-			  undefined ->
-			      State0#state.next_protocol;
-			  _ ->
-			      NextProtocol
-		      end,
-    
+
+	{ExpectNPN, Protocol} = case Protocol0 of
+		undefined -> {false, CurrentProtocol};
+		_ -> {ProtoExt =:= npn, Protocol0}
+	end,
+
     State = State0#state{key_algorithm = KeyAlgorithm,
 				 negotiated_version = Version,
 			 connection_states = ConnectionStates,
 			 premaster_secret = PremasterSecret,
-			 expecting_next_protocol_negotiation = NextProtocol =/= undefined,
-			 next_protocol = NewNextProtocol},
+			 expecting_next_protocol_negotiation = ExpectNPN,
+			 negotiated_protocol = Protocol},
     
     case ssl_session:is_new(OldId, NewId) of
 	true ->
@@ -371,7 +370,7 @@ abbreviated(#finished{verify_data = Data} = Finished,
 abbreviated(#next_protocol{selected_protocol = SelectedProtocol},
 	    #state{role = server, expecting_next_protocol_negotiation = true} = State0,
 	    Connection) ->
-    {Record, State} = Connection:next_record(State0#state{next_protocol = SelectedProtocol}),
+    {Record, State} = Connection:next_record(State0#state{negotiated_protocol = SelectedProtocol}),
     Connection:next_state(abbreviated, abbreviated, Record, State#state{expecting_next_protocol_negotiation = false});
 
 abbreviated(timeout, State, _) ->
@@ -593,7 +592,7 @@ cipher(#certificate_verify{signature = Signature, hashsign_algorithm = CertHashS
 
 %% client must send a next protocol message if we are expecting it
 cipher(#finished{}, #state{role = server, expecting_next_protocol_negotiation = true,
-			   next_protocol = undefined, negotiated_version = Version} = State0,
+			   negotiated_protocol = undefined, negotiated_version = Version} = State0,
        Connection) ->
     Connection:handle_own_alert(?ALERT_REC(?FATAL,?UNEXPECTED_MESSAGE), Version, cipher, State0);
 
@@ -623,7 +622,7 @@ cipher(#finished{verify_data = Data} = Finished,
 cipher(#next_protocol{selected_protocol = SelectedProtocol},
        #state{role = server, expecting_next_protocol_negotiation = true,
 	      expecting_finished = true} = State0, Connection) ->
-    {Record, State} = Connection:next_record(State0#state{next_protocol = SelectedProtocol}),
+    {Record, State} = Connection:next_record(State0#state{negotiated_protocol = SelectedProtocol}),
     Connection:next_state(cipher, cipher, Record, State#state{expecting_next_protocol_negotiation = false});
 
 cipher(timeout, State, _) ->
@@ -759,10 +758,10 @@ handle_sync_event({get_opts, OptTags}, _From, StateName,
 			 socket_options = SockOpts} = State) ->
     OptsReply = get_socket_opts(Transport, Socket, OptTags, SockOpts, []),
     {reply, OptsReply, StateName, State, get_timeout(State)};
-handle_sync_event(negotiated_next_protocol, _From, StateName, #state{next_protocol = undefined} = State) ->
-    {reply, {error, next_protocol_not_negotiated}, StateName, State, get_timeout(State)};
-handle_sync_event(negotiated_next_protocol, _From, StateName, #state{next_protocol = NextProtocol} = State) ->
-    {reply, {ok, NextProtocol}, StateName, State, get_timeout(State)};
+handle_sync_event(negotiated_protocol, _From, StateName, #state{negotiated_protocol = undefined} = State) ->
+    {reply, {error, protocol_not_negotiated}, StateName, State, get_timeout(State)};
+handle_sync_event(negotiated_protocol, _From, StateName, #state{negotiated_protocol = SelectedProtocol} = State) ->
+    {reply, {ok, SelectedProtocol}, StateName, State, get_timeout(State)};
 handle_sync_event({set_opts, Opts0}, _From, StateName0, 
 		  #state{socket_options = Opts1, 
 			 protocol_cb = Connection,
@@ -1484,11 +1483,11 @@ finalize_handshake(State0, StateName, Connection) ->
 
 next_protocol(#state{role = server} = State, _) ->
     State;
-next_protocol(#state{next_protocol = undefined} = State, _) ->
+next_protocol(#state{negotiated_protocol = undefined} = State, _) ->
     State;
 next_protocol(#state{expecting_next_protocol_negotiation = false} = State, _) ->
     State;
-next_protocol(#state{next_protocol = NextProtocol} = State0, Connection) ->
+next_protocol(#state{negotiated_protocol = NextProtocol} = State0, Connection) ->
     NextProtocolMessage = ssl_handshake:next_protocol(NextProtocol),
     Connection:send_handshake(NextProtocolMessage, State0).
 
diff --git a/lib/ssl/src/ssl_connection.hrl b/lib/ssl/src/ssl_connection.hrl
index ac3b26e4bf..e569d706af 100644
--- a/lib/ssl/src/ssl_connection.hrl
+++ b/lib/ssl/src/ssl_connection.hrl
@@ -78,7 +78,7 @@
 	  allow_renegotiate = true                    ::boolean(),
           expecting_next_protocol_negotiation = false ::boolean(),
 	  expecting_finished =                  false ::boolean(),
-          next_protocol = undefined                   :: undefined | binary(),
+          negotiated_protocol = undefined             :: undefined | binary(),
 	  client_ecc,          % {Curves, PointFmt}
 	  tracker              :: pid() %% Tracker process for listen socket
 	 }).
diff --git a/lib/ssl/src/ssl_handshake.erl b/lib/ssl/src/ssl_handshake.erl
index 5c5f386c6f..493e5a87d9 100644
--- a/lib/ssl/src/ssl_handshake.erl
+++ b/lib/ssl/src/ssl_handshake.erl
@@ -136,6 +136,7 @@ client_hello_extensions(Host, Version, CipherSuites, SslOpts, ConnectionStates,
        hash_signs = advertised_hash_signs(Version),
        ec_point_formats = EcPointFormats,
        elliptic_curves = EllipticCurves,
+       alpn = encode_alpn(SslOpts#ssl_options.alpn_advertised_protocols, Renegotiation),
        next_protocol_negotiation =
 	   encode_client_protocol_negotiation(SslOpts#ssl_options.next_protocol_selector,
 					      Renegotiation),
@@ -764,6 +765,11 @@ encode_hello_extensions([], Acc) ->
     Size = byte_size(Acc),
     <<?UINT16(Size), Acc/binary>>;
 
+encode_hello_extensions([#alpn{extension_data = ExtensionData} | Rest], Acc) ->
+	Len = byte_size(ExtensionData),
+    ExtLen = Len + 2,
+	encode_hello_extensions(Rest, <<?UINT16(?ALPN_EXT), ?UINT16(ExtLen), ?UINT16(Len),
+					ExtensionData/binary, Acc/binary>>);
 encode_hello_extensions([#next_protocol_negotiation{extension_data = ExtensionData} | Rest], Acc) ->
     Len = byte_size(ExtensionData),
     encode_hello_extensions(Rest, <<?UINT16(?NEXTPROTONEG_EXT), ?UINT16(Len),
@@ -862,6 +868,25 @@ decode_client_key(ClientKey, Type, Version) ->
 decode_server_key(ServerKey, Type, Version) ->
     dec_server_key(ServerKey, key_exchange_alg(Type), Version).
 
+%%
+%% Description: Encode and decode functions for ALPN extension data.
+%%--------------------------------------------------------------------
+
+%% While the RFC opens the door to allow ALPN during renegotiation, in practice
+%% this does not work and it is recommended to ignore any ALPN extension during
+%% renegotiation, as done here.
+encode_alpn(_, true) ->
+    undefined;
+encode_alpn(undefined, _) ->
+    undefined;
+encode_alpn(Protocols, _) ->
+    #alpn{extension_data = lists:foldl(fun encode_protocol/2, <<>>, Protocols)}.
+
+decode_alpn(undefined) ->
+    undefined;
+decode_alpn(#alpn{extension_data=Data}) ->
+    decode_protocols(Data, []).
+
 encode_client_protocol_negotiation(undefined, _) ->
     undefined;
 encode_client_protocol_negotiation(_, false) ->
@@ -1124,8 +1149,10 @@ handle_client_hello_extensions(RecordCB, Random, ClientCipherSuites,
 			       #hello_extensions{renegotiation_info = Info,
 						 srp = SRP,
 						 ec_point_formats = ECCFormat,
+                         alpn = ALPN,
 						 next_protocol_negotiation = NextProtocolNegotiation}, Version,
-			       #ssl_options{secure_renegotiate = SecureRenegotation} = Opts,
+			       #ssl_options{secure_renegotiate = SecureRenegotation,
+                                            alpn_preferred_protocols = ALPNPreferredProtocols} = Opts,
 			       #session{cipher_suite = NegotiatedCipherSuite,
 					compression_method = Compression} = Session0,
 			       ConnectionStates0, Renegotiation) ->
@@ -1134,19 +1161,34 @@ handle_client_hello_extensions(RecordCB, Random, ClientCipherSuites,
 						      Random, NegotiatedCipherSuite, 
 						      ClientCipherSuites, Compression,
 						      ConnectionStates0, Renegotiation, SecureRenegotation),
-    ProtocolsToAdvertise = handle_next_protocol_extension(NextProtocolNegotiation, Renegotiation, Opts),
-   
+
     ServerHelloExtensions =  #hello_extensions{
 				renegotiation_info = renegotiation_info(RecordCB, server,
 									ConnectionStates, Renegotiation),
-				ec_point_formats = server_ecc_extension(Version, ECCFormat),
-				next_protocol_negotiation =
-				    encode_protocols_advertised_on_server(ProtocolsToAdvertise)
+				ec_point_formats = server_ecc_extension(Version, ECCFormat)
 			       },
-    {Session, ConnectionStates, ServerHelloExtensions}.
+
+    %% If we receive an ALPN extension and have ALPN configured for this connection,
+    %% we handle it. Otherwise we check for the NPN extension.
+    if
+        ALPN =/= undefined, ALPNPreferredProtocols =/= undefined ->
+			case handle_alpn_extension(ALPNPreferredProtocols, decode_alpn(ALPN)) of
+                #alert{} = Alert ->
+                    Alert;
+                Protocol ->
+                    {Session, ConnectionStates, Protocol,
+                        ServerHelloExtensions#hello_extensions{alpn=encode_alpn([Protocol], Renegotiation)}}
+            end;
+        true ->
+            ProtocolsToAdvertise = handle_next_protocol_extension(NextProtocolNegotiation, Renegotiation, Opts),
+            {Session, ConnectionStates, undefined,
+				ServerHelloExtensions#hello_extensions{next_protocol_negotiation=
+                	encode_protocols_advertised_on_server(ProtocolsToAdvertise)}}
+    end.
 
 handle_server_hello_extensions(RecordCB, Random, CipherSuite, Compression,
 			       #hello_extensions{renegotiation_info = Info,
+                                                 alpn = ALPN,
 						 next_protocol_negotiation = NextProtocolNegotiation}, Version,
 			       #ssl_options{secure_renegotiate = SecureRenegotation,
 					    next_protocol_selector = NextProtoSelector},
@@ -1155,11 +1197,23 @@ handle_server_hello_extensions(RecordCB, Random, CipherSuite, Compression,
 						      CipherSuite, undefined,
 						      Compression, ConnectionStates0,
 						      Renegotiation, SecureRenegotation),
-    case handle_next_protocol(NextProtocolNegotiation, NextProtoSelector, Renegotiation) of
-	#alert{} = Alert ->
-	    Alert;
-	Protocol ->
-	    {ConnectionStates, Protocol}
+
+    %% If we receive an ALPN extension then this is the protocol selected,
+    %% otherwise handle the NPN extension.
+    case decode_alpn(ALPN) of
+        %% ServerHello contains exactly one protocol: the one selected.
+        %% We also ignore the ALPN extension during renegotiation (see encode_alpn/2).
+        [Protocol] when not Renegotiation ->
+            {ConnectionStates, alpn, Protocol};
+        undefined ->
+            case handle_next_protocol(NextProtocolNegotiation, NextProtoSelector, Renegotiation) of
+                #alert{} = Alert ->
+                    Alert;
+                Protocol ->
+                    {ConnectionStates, npn, Protocol}
+            end;
+        _ -> %% {error, _Reason} or a list of 0/2+ protocols.
+            ?ALERT_REC(?FATAL, ?HANDSHAKE_FAILURE)
     end.
 
 select_version(RecordCB, ClientVersion, Versions) ->
@@ -1267,10 +1321,11 @@ hello_extensions_list(#hello_extensions{renegotiation_info = RenegotiationInfo,
 					hash_signs = HashSigns,
 					ec_point_formats = EcPointFormats,
 					elliptic_curves = EllipticCurves,
+                                        alpn = ALPN,
 					next_protocol_negotiation = NextProtocolNegotiation,
 					sni = Sni}) ->
     [Ext || Ext <- [RenegotiationInfo, SRP, HashSigns,
-		    EcPointFormats, EllipticCurves, NextProtocolNegotiation, Sni], Ext =/= undefined].
+		    EcPointFormats, EllipticCurves, ALPN, NextProtocolNegotiation, Sni], Ext =/= undefined].
 
 srp_user(#ssl_options{srp_identity = {UserName, _}}) ->
     #srp{username = UserName};
@@ -1708,6 +1763,10 @@ dec_server_key_signature(_, _, _) ->
 
 dec_hello_extensions(<<>>, Acc) ->
     Acc;
+dec_hello_extensions(<<?UINT16(?ALPN_EXT), ?UINT16(ExtLen), ?UINT16(Len), ExtensionData:Len/binary, Rest/binary>>, Acc)
+        when Len + 2 =:= ExtLen ->
+    ALPN = #alpn{extension_data = ExtensionData},
+    dec_hello_extensions(Rest, Acc#hello_extensions{alpn = ALPN});
 dec_hello_extensions(<<?UINT16(?NEXTPROTONEG_EXT), ?UINT16(Len), ExtensionData:Len/binary, Rest/binary>>, Acc) ->
     NextP = #next_protocol_negotiation{extension_data = ExtensionData},
     dec_hello_extensions(Rest, Acc#hello_extensions{next_protocol_negotiation = NextP});
@@ -1788,18 +1847,19 @@ dec_sni(<<?BYTE(_), ?UINT16(Len), _:Len, Rest/binary>>) -> dec_sni(Rest);
 dec_sni(_) -> undefined.
 
 decode_next_protocols({next_protocol_negotiation, Protocols}) ->
-    decode_next_protocols(Protocols, []).
-decode_next_protocols(<<>>, Acc) ->
+    decode_protocols(Protocols, []).
+
+decode_protocols(<<>>, Acc) ->
     lists:reverse(Acc);
-decode_next_protocols(<<?BYTE(Len), Protocol:Len/binary, Rest/binary>>, Acc) ->
+decode_protocols(<<?BYTE(Len), Protocol:Len/binary, Rest/binary>>, Acc) ->
     case Len of
         0 ->
-            {error, invalid_next_protocols};
+            {error, invalid_protocols};
         _ ->
-            decode_next_protocols(Rest, [Protocol|Acc])
+            decode_protocols(Rest, [Protocol|Acc])
     end;
-decode_next_protocols(_Bytes, _Acc) ->
-    {error, invalid_next_protocols}.
+decode_protocols(_Bytes, _Acc) ->
+    {error, invalid_protocols}.
 
 %% encode/decode stream of certificate data to/from list of certificate data
 certs_to_list(ASN1Certs) ->
@@ -1853,6 +1913,17 @@ key_exchange_alg(_) ->
 
 %%-------------Extension handling --------------------------------
 
+%% Receive protocols, choose one from the list, return it.
+handle_alpn_extension(_, {error, _Reason}) ->
+    ?ALERT_REC(?FATAL, ?HANDSHAKE_FAILURE);
+handle_alpn_extension([], _) ->
+	?ALERT_REC(?FATAL, ?NO_APPLICATION_PROTOCOL);
+handle_alpn_extension([ServerProtocol|Tail], ClientProtocols) ->
+	case lists:member(ServerProtocol, ClientProtocols) of
+		true -> ServerProtocol;
+		false -> handle_alpn_extension(Tail, ClientProtocols)
+	end.
+
 handle_next_protocol(undefined,
 		     _NextProtocolSelector, _Renegotiating) ->
     undefined;
diff --git a/lib/ssl/src/ssl_handshake.hrl b/lib/ssl/src/ssl_handshake.hrl
index 80284faef0..91f674a6fc 100644
--- a/lib/ssl/src/ssl_handshake.hrl
+++ b/lib/ssl/src/ssl_handshake.hrl
@@ -95,6 +95,7 @@
 -record(hello_extensions, {
 	  renegotiation_info,
 	  hash_signs,          % supported combinations of hashes/signature algos
+          alpn,
 	  next_protocol_negotiation = undefined, % [binary()]
 	  srp,
 	  ec_point_formats,
@@ -301,6 +302,14 @@
 	 }).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Application-Layer Protocol Negotiation  RFC 7301
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-define(ALPN_EXT, 16).
+
+-record(alpn, {extension_data}).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Next Protocol Negotiation
 %% (http://tools.ietf.org/html/draft-agl-tls-nextprotoneg-02)
 %% (http://technotes.googlecode.com/git/nextprotoneg.html)
diff --git a/lib/ssl/src/ssl_internal.hrl b/lib/ssl/src/ssl_internal.hrl
index 8df79f9e8c..e09a72a3f3 100644
--- a/lib/ssl/src/ssl_internal.hrl
+++ b/lib/ssl/src/ssl_internal.hrl
@@ -116,6 +116,8 @@
 	  hibernate_after      :: boolean(),
 	  %% This option should only be set to true by inet_tls_dist
 	  erl_dist = false     :: boolean(),
+          alpn_advertised_protocols = undefined :: [binary()],
+          alpn_preferred_protocols = undefined :: [binary()],
 	  next_protocols_advertised = undefined, %% [binary()],
 	  next_protocol_selector = undefined,  %% fun([binary()]) -> binary())
 	  log_alert             :: boolean(),
diff --git a/lib/ssl/src/tls_connection.erl b/lib/ssl/src/tls_connection.erl
index 77d3aa7889..0577222980 100644
--- a/lib/ssl/src/tls_connection.erl
+++ b/lib/ssl/src/tls_connection.erl
@@ -188,19 +188,27 @@ hello(Hello = #client_hello{client_version = ClientVersion,
 		     renegotiation = {Renegotiation, _},
 		     session_cache = Cache,
 		     session_cache_cb = CacheCb,
+		     negotiated_protocol = CurrentProtocol,
 		     ssl_options = SslOpts}) ->
     case tls_handshake:hello(Hello, SslOpts, {Port, Session0, Cache, CacheCb,
 					      ConnectionStates0, Cert}, Renegotiation) of
+        #alert{} = Alert ->
+            handle_own_alert(Alert, ClientVersion, hello, State);
         {Version, {Type, Session},
-	 ConnectionStates, ServerHelloExt} ->
+	 ConnectionStates, Protocol0, ServerHelloExt} ->
+
+	    Protocol = case Protocol0 of
+		undefined -> CurrentProtocol;
+		_ -> Protocol0
+	    end,
+
             HashSign = ssl_handshake:select_hashsign(HashSigns, Cert, 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)
+					     client_ecc = {EllipticCurves, EcPointFormats},
+					     negotiated_protocol = Protocol}, ?MODULE)
     end;
 hello(Hello,
       #state{connection_states = ConnectionStates0,
@@ -211,9 +219,9 @@ hello(Hello,
     case tls_handshake:hello(Hello, SslOptions, ConnectionStates0, Renegotiation) of
 	#alert{} = Alert ->
 	    handle_own_alert(Alert, ReqVersion, hello, State);
-	{Version, NewId, ConnectionStates, NextProtocol} ->
+	{Version, NewId, ConnectionStates, ProtoExt, Protocol} ->
 	    ssl_connection:handle_session(Hello, 
-					  Version, NewId, ConnectionStates, NextProtocol, State)
+					  Version, NewId, ConnectionStates, ProtoExt, Protocol, State)
     end;
 
 hello(Msg, State) ->
diff --git a/lib/ssl/src/tls_handshake.erl b/lib/ssl/src/tls_handshake.erl
index 548ec4aebe..2d50dd7e46 100644
--- a/lib/ssl/src/tls_handshake.erl
+++ b/lib/ssl/src/tls_handshake.erl
@@ -245,8 +245,10 @@ handle_client_hello_extensions(Version, Type, Random, CipherSuites,
     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}
+	#alert{} = Alert ->
+	    Alert;
+	{Session, ConnectionStates, Protocol, ServerHelloExt} ->
+	    {Version, {Type, Session}, ConnectionStates, Protocol, ServerHelloExt}
     catch throw:Alert ->
 	    Alert
     end.
@@ -259,7 +261,7 @@ handle_server_hello_extensions(Version, SessionId, Random, CipherSuite,
 						      SslOpt, ConnectionStates0, Renegotiation) of
 	#alert{} = Alert ->
 	    Alert;
-	{ConnectionStates, Protocol} ->
-	    {Version, SessionId, ConnectionStates, Protocol}
+	{ConnectionStates, ProtoExt, Protocol} ->
+	    {Version, SessionId, ConnectionStates, ProtoExt, Protocol}
     end.