Merge branch 'anders/diameter/performance/OTP-14343'

* anders/diameter/performance/OTP-14343: (50 commits)
  Let spawn_opt config replace erlang:spawn_opt/2 for request processes
  Move (most of) diameter_gen.hrl to diameter_gen.erl
  Change signature associated with dictionary @custom_type/@codecs
  Avoid sending answer terms between processes unnecessarily
  Refactor handling of incoming requests
  Restore diameter_codec:decode/2, update diameter_codec(3)
  Add diameter_codec option ordered_encode
  Restore undocumented Failed-AVP setting convenience
  Fix/simplify setting of one Failed-AVP
  Avoid recreating records
  Avoid recreating records
  Avoid recreating records
  Avoid recreating records
  Adapt test suites to modified encode/decode
  Simplify diameter_caps construction
  Don't compute URI defaults unnecessarily
  Don't deconstruct {TPid, Caps} unnecessarily
  Remove use of process dictionary in decode
  Remove minor diameter_config bloat
  Fix maximum AVP arity check
  ...

14 files changed, 1951 insertions, 1514 deletions

diff --git a/lib/diameter/src/base/diameter_capx.erl b/lib/diameter/src/base/diameter_capx.erl
index 07a678c617..837125339a 100644
--- a/lib/diameter/src/base/diameter_capx.erl
+++ b/lib/diameter/src/base/diameter_capx.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2015. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -94,6 +94,9 @@ recv_CER(CER, Svc, Dict) ->
 recv_CEA(CEA, Svc, Dict) ->
     try_it([fun rCEA/3, CEA, Svc, Dict]).
 
+-spec make_caps(#diameter_caps{}, [{atom(), term()}])
+   -> tried(#diameter_caps{}).
+
 make_caps(Caps, Opts) ->
     try_it([fun mk_caps/2, Caps, Opts]).
 
@@ -110,31 +113,20 @@ try_it([Fun | Args]) ->
 %% mk_caps/2
 
 mk_caps(Caps0, Opts) ->
-    {Caps, _} = lists:foldl(fun set_cap/2,
-                            {Caps0, #diameter_caps{_ = false}},
-                            Opts),
-    Caps.
-
--define(SC(K,F),
-        set_cap({K, Val}, {Caps, #diameter_caps{F = false} = C}) ->
-            {Caps#diameter_caps{F = cap(K, copy(Val))},
-             C#diameter_caps{F = true}}).
-
-?SC('Origin-Host',         origin_host);
-?SC('Origin-Realm',        origin_realm);
-?SC('Host-IP-Address',     host_ip_address);
-?SC('Vendor-Id',           vendor_id);
-?SC('Product-Name',        product_name);
-?SC('Origin-State-Id',     origin_state_id);
-?SC('Supported-Vendor-Id', supported_vendor_id);
-?SC('Auth-Application-Id', auth_application_id);
-?SC('Inband-Security-Id',  inband_security_id);
-?SC('Acct-Application-Id', acct_application_id);
-?SC('Vendor-Specific-Application-Id', vendor_specific_application_id);
-?SC('Firmware-Revision',   firmware_revision);
-
-set_cap({Key, _}, _) ->
-    ?THROW({duplicate, Key}).
+    Fields = diameter_gen_base_rfc3588:'#info-'(diameter_base_CER, fields),
+    Defs = lists:zip(Fields, tl(tuple_to_list(Caps0))),
+    Unset = maps:from_list([{F, true} || F <- lists:droplast(Fields)]), %% no 'AVP'
+    {Caps, _} = lists:foldl(fun set_cap/2, {Defs, Unset}, Opts),
+    #diameter_caps{} = list_to_tuple([diameter_caps | [V || {_,V} <- Caps]]).
+
+set_cap({F,V}, {Caps, Unset}) ->
+    case Unset of
+        #{F := true} ->
+            {lists:keyreplace(F, 1, Caps, {F, cap(F, copy(V))}),
+             maps:remove(F, Unset)};
+        _ ->
+            ?THROW({duplicate, F})
+    end.
 
 cap(K, V)
   when K == 'Origin-Host';
@@ -349,7 +341,7 @@ cs(LS, RS) ->
 cea_from_cer(CER, Dict) ->
     RecName = Dict:msg2rec('CEA'),
     [_ | Values] = Dict:'#get-'(CER),
-    Dict:'#set-'(Values, Dict:'#new-'(RecName)).
+    Dict:'#new-'([RecName | Values]).
 
 %% rCEA/3
 
diff --git a/lib/diameter/src/base/diameter_codec.erl b/lib/diameter/src/base/diameter_codec.erl
index 1ea5357924..82fa796e69 100644
--- a/lib/diameter/src/base/diameter_codec.erl
+++ b/lib/diameter/src/base/diameter_codec.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2015. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -20,11 +20,8 @@
 
 -module(diameter_codec).
 
--export([encode/2,
-         decode/2,
-         decode/3,
-         setopts/1,
-         getopt/1,
+-export([encode/2, encode/3,
+         decode/2, decode/3, decode/4,
          collect_avps/1,
          decode_header/1,
          sequence_numbers/1,
@@ -33,13 +30,17 @@
          msg_id/1]).
 
 %% Towards generated encoders (from diameter_gen.hrl).
--export([pack_avp/1,
+-export([pack_data/2,
          pack_avp/2]).
 
 -include_lib("diameter/include/diameter.hrl").
 -include("diameter_internal.hrl").
 
--define(MASK(N,I), ((I) band (1 bsl (N)))).
+-define(PAD(Len), ((4 - (Len rem 4)) rem 4)).
+-define(BIT(B,I), (if B -> I; true -> 0 end)).
+-define(BIT(B),   ?BIT(B,1)).
+-define(FLAGS(R,P,E,T), ?BIT(R):1, ?BIT(P):1, ?BIT(E):1, ?BIT(T):1, 0:4).
+-define(FLAG(B,D), (if is_boolean(B) -> B; true -> 0 /= (D) end)).
 
 -type u32() :: 0..16#FFFFFFFF.
 -type u24() :: 0..16#FFFFFF.
@@ -62,62 +63,29 @@
 %%    +-+-+-+-+-+-+-+-+-+-+-+-+-
 
 %%% ---------------------------------------------------------------------------
-%%% # setopts/1
-%%% # getopt/1
+%%% # encode/2
 %%% ---------------------------------------------------------------------------
 
-%% These functions are a compromise in the same vein as the use of the
-%% process dictionary in diameter_gen.hrl in generated codec modules.
-%% Instead of rewriting the entire dictionary generation to pass
-%% encode/decode options around, the calling process sets them by
-%% calling setopts/1. At current, the only option is whether or not to
-%% decode binaries as strings, which is used by diameter_types.
-
-setopts(Opts)
-  when is_list(Opts) ->
-    lists:foreach(fun setopt/1, Opts).
-
-%% The default string_decode true is for backwards compatibility.
-setopt({K, false = B})
-  when K == string_decode;
-       K == strict_mbit ->
-    setopt(K, B);
-
-%% Regard anything but the generated RFC 3588 dictionary as modern.
-%% This affects the interpretation of defaults during the decode
-%% of values of type DiameterURI, this having changed from RFC 3588.
-%% (So much for backwards compatibility.)
-setopt({common_dictionary, diameter_gen_base_rfc3588}) ->
-    setopt(rfc, 3588);
-
-setopt(_) ->
-    ok.
-
-setopt(Key, Value) ->
-    put({diameter, Key}, Value).
-
-getopt(Key) ->
-    case get({diameter, Key}) of
-        undefined when Key == string_decode;
-                       Key == strict_mbit ->
-            true;
-        undefined when Key == rfc ->
-            6733;
-        V ->
-            V
-    end.
+%% The representative encode documented in diameter_codec(3). As of
+%% the options that affect encode (eg. ordered_encode), it's no longer
+%% *the* encode.
+
+encode(Mod, Msg) ->
+    encode(Mod, #{ordered_encode => true}, Msg).
 
 %%% ---------------------------------------------------------------------------
-%%% # encode/2
+%%% # encode/3
 %%% ---------------------------------------------------------------------------
 
--spec encode(module(), Msg :: term())
+-spec encode(module(),
+             map(),
+             Msg :: term())
    -> #diameter_packet{}
     | no_return().
 
-encode(Mod, #diameter_packet{} = Pkt) ->
+encode(Mod, Opts, #diameter_packet{} = Pkt) ->
     try
-        e(Mod, Pkt)
+        enc(Mod, Opts, Pkt)
     catch
         exit: {Reason, Stack, #diameter_header{} = H} = T ->
             %% Exit with a header in the reason to let the caller
@@ -130,91 +98,97 @@ encode(Mod, #diameter_packet{} = Pkt) ->
             exit({?MODULE, encode, T})
     end;
 
-encode(Mod, Msg) ->
+encode(Mod, Opts, Msg) ->
     Seq = diameter_session:sequence(),
     Hdr = #diameter_header{version = ?DIAMETER_VERSION,
                            end_to_end_id = Seq,
                            hop_by_hop_id = Seq},
-    encode(Mod,  #diameter_packet{header = Hdr,
-                                  msg = Msg}).
+    encode(Mod, Opts, #diameter_packet{header = Hdr,
+                                       msg = Msg}).
+
+%% enc/3
 
-e(_, #diameter_packet{msg = [#diameter_header{} = Hdr | As]} = Pkt) ->
-    try encode_avps(reorder(As)) of
+enc(_, Opts, #diameter_packet{msg = [#diameter_header{} = Hdr | As]}
+             = Pkt) ->
+    try encode_avps(reorder(As), Opts) of
         Avps ->
-            Length = size(Avps) + 20,
+            Bin = list_to_binary(Avps),
+            Len = 20 + size(Bin),
 
             #diameter_header{version = Vsn,
+                             is_request = R,
+                             is_proxiable = P,
+                             is_error = E,
+                             is_retransmitted = T,
                              cmd_code = Code,
                              application_id = Aid,
                              hop_by_hop_id  = Hid,
                              end_to_end_id  = Eid}
                 = Hdr,
 
-            Flags = make_flags(0, Hdr),
-
             Pkt#diameter_packet{header = Hdr,
-                                bin = <<Vsn:8, Length:24,
-                                        Flags:8, Code:24,
+                                bin = <<Vsn:8, Len:24,
+                                        ?FLAGS(R,P,E,T), Code:24,
                                         Aid:32,
                                         Hid:32,
                                         Eid:32,
-                                        Avps/binary>>}
+                                        Bin/binary>>}
     catch
         error: Reason ->
             exit({Reason, diameter_lib:get_stacktrace(), Hdr})
     end;
 
-e(Mod, #diameter_packet{header = Hdr0, msg = Msg} = Pkt) ->
+enc(Mod, Opts, #diameter_packet{header = Hdr0, msg = Msg} = Pkt) ->
+    MsgName = rec2msg(Mod, Msg),
+    {Code, Flags, Aid} = msg_header(Mod, MsgName, Hdr0),
+
     #diameter_header{version = Vsn,
+                     is_request = R,
+                     is_proxiable = P,
+                     is_error = E,
+                     is_retransmitted = T,
                      hop_by_hop_id = Hid,
                      end_to_end_id = Eid}
         = Hdr0,
 
-    MsgName = rec2msg(Mod, Msg),
-    {Code, Flags0, Aid} = msg_header(Mod, MsgName, Hdr0),
-    Flags = make_flags(Flags0, Hdr0),
-    Hdr = Hdr0#diameter_header{cmd_code = Code,
-                               application_id = Aid,
-                               is_request       = 0 /= ?MASK(7, Flags),
-                               is_proxiable     = 0 /= ?MASK(6, Flags),
-                               is_error         = 0 /= ?MASK(5, Flags),
-                               is_retransmitted = 0 /= ?MASK(4, Flags)},
+    RB = ?FLAG(R, Flags band 2#10000000),
+    PB = ?FLAG(P, Flags band 2#01000000),
+    EB = ?FLAG(E, Flags band 2#00100000),
+    TB = ?FLAG(T, Flags band 2#00010000),
+
     Values = values(Msg),
 
-    try encode_avps(Mod, MsgName, Values) of
+    try encode_avps(Mod, MsgName, Values, Opts) of
         Avps ->
-            Length = size(Avps) + 20,
-            Pkt#diameter_packet{header = Hdr#diameter_header{length = Length},
-                                bin = <<Vsn:8, Length:24,
-                                        Flags:8, Code:24,
+            Bin = list_to_binary(Avps),
+            Len = 20 + size(Bin),
+
+            Hdr = Hdr0#diameter_header{length = Len,
+                                       cmd_code = Code,
+                                       application_id = Aid,
+                                       is_request       = RB,
+                                       is_proxiable     = PB,
+                                       is_error         = EB,
+                                       is_retransmitted = TB},
+
+            Pkt#diameter_packet{header = Hdr,
+                                bin = <<Vsn:8, Len:24,
+                                        ?FLAGS(RB, PB, EB, TB), Code:24,
                                         Aid:32,
                                         Hid:32,
                                         Eid:32,
-                                        Avps/binary>>}
+                                        Bin/binary>>}
     catch
         error: Reason ->
+            Hdr = Hdr0#diameter_header{cmd_code = Code,
+                                       application_id = Aid,
+                                       is_request       = RB,
+                                       is_proxiable     = PB,
+                                       is_error         = EB,
+                                       is_retransmitted = TB},
             exit({Reason, diameter_lib:get_stacktrace(), Hdr})
     end.
 
-%% make_flags/2
-
-make_flags(Flags0, #diameter_header{is_request       = R,
-                                    is_proxiable     = P,
-                                    is_error         = E,
-                                    is_retransmitted = T}) ->
-    {Flags, 3} = lists:foldl(fun(B,{F,N}) -> {mf(B,F,N), N-1} end,
-                             {Flags0, 7},
-                             [R,P,E,T]),
-    Flags.
-
-mf(undefined, F, _) ->
-    F;
-mf(B, F, N) ->  %% reset the affected bit
-    (F bxor (F band (1 bsl N))) bor bit(B, N).
-
-bit(true, N)  -> 1 bsl N;
-bit(false, _) -> 0.
-
 %% values/1
 
 values([H|T])
@@ -223,7 +197,7 @@ values([H|T])
 values(Avps) ->
     Avps.
 
-%% encode_avps/3
+%% encode_avps/4
 
 %% Specifying values as a #diameter_avp list bypasses arity and other
 %% checks: the values are expected to be already encoded and the AVP's
@@ -231,12 +205,12 @@ values(Avps) ->
 %% these have to be able to resend whatever comes.
 
 %% Message as a list of #diameter_avp{} ...
-encode_avps(_, _, [#diameter_avp{} | _] = Avps) ->
-    encode_avps(reorder(Avps));
+encode_avps(_, _, [#diameter_avp{} | _] = Avps, Opts) ->
+    encode_avps(reorder(Avps), Opts);
 
 %% ... or as a tuple list or record.
-encode_avps(Mod, MsgName, Values) ->
-    Mod:encode_avps(MsgName, Values).
+encode_avps(Mod, MsgName, Values, Opts) ->
+    Mod:encode_avps(MsgName, Values, Opts).
 
 %% reorder/1
 %%
@@ -277,10 +251,10 @@ reorder([H | T], Acc) ->
 reorder([], _) ->
     false.
 
-%% encode_avps/1
+%% encode_avps/2
 
-encode_avps(Avps) ->
-    list_to_binary(lists:map(fun pack_avp/1, Avps)).
+encode_avps(Avps, Opts) ->
+    [pack_avp(A, Opts) || A <- Avps].
 
 %% msg_header/3
 
@@ -308,38 +282,50 @@ rec2msg(Mod, Rec) ->
 %%% # decode/2
 %%% ---------------------------------------------------------------------------
 
+%% The representative default decode documented in diameter_codec(3).
+%% As of the options that affect decode (eg. string_decode), it's no
+%% longer *the* decode.
+
+decode(Mod, Pkt) ->
+    Opts = #{string_decode => true,
+             strict_mbit => true,
+             rfc => 6733},
+    decode(Mod, Opts, Pkt).
+
+%%% ---------------------------------------------------------------------------
+%%% # decode/3
+%%% ---------------------------------------------------------------------------
+
 %% Unsuccessfully decoded AVPs will be placed in #diameter_packet.errors.
 
--spec decode(module() | {module(), module()}, #diameter_packet{} | binary())
+-spec decode(module() | {module(), module()},
+             map(),
+             #diameter_packet{} | binary())
    -> #diameter_packet{}.
 
 %% An Answer setting the E-bit. The application dictionary is needed
-%% for the best-effort decode of Failed-AVP, and the best way to make
-%% this available to the AVP decode in diameter_gen.hrl, without
-%% having to rewrite the entire codec generation, is to place it in
-%% the process dictionary. It's the code in diameter_gen.hrl (that's
-%% included by every generated codec module) that looks for the entry.
-%% Not ideal, but it solves the problem relatively simply.
-decode({Mod, Mod}, Pkt) ->
-    decode(Mod, Pkt);
-decode({Mod, AppMod}, Pkt) ->
-    Key = {?MODULE, dictionary},
-    put(Key, AppMod),
-    try
-        decode(Mod, Pkt)
-    after
-        erase(Key)
-    end;
+%% for the best-effort decode of Failed-AVP.
+decode({Mod, AppMod}, Opts, Pkt) ->
+    decode(Mod, AppMod, Opts, Pkt);
 
 %% Or not: a request, or an answer not setting the E-bit.
-decode(Mod, Pkt) ->
-    decode(Mod:id(), Mod, Pkt).
+decode(Mod, Opts, Pkt) ->
+    decode(Mod, Mod, Opts, Pkt).
+
+%% decode/4
+
+decode(Id, Mod, Opts, Pkt)
+  when is_integer(Id) ->
+    decode(Id, Mod, Mod, Opts, Pkt);
 
-%% decode/3
+decode(Mod, AppMod, Opts, Pkt) ->
+    decode(Mod:id(), Mod, AppMod, Opts, Pkt).
+
+%% decode/5
 
 %% Relay application: just extract the avp's without any decoding of
 %% their data since we don't know the application in question.
-decode(?APP_ID_RELAY, _, #diameter_packet{} = Pkt) ->
+decode(?APP_ID_RELAY, _, _, _, #diameter_packet{} = Pkt) ->
     case collect_avps(Pkt) of
         {E, As} ->
             Pkt#diameter_packet{avps = As,
@@ -349,7 +335,7 @@ decode(?APP_ID_RELAY, _, #diameter_packet{} = Pkt) ->
     end;
 
 %% Otherwise decode using the dictionary.
-decode(_, Mod, #diameter_packet{header = Hdr} = Pkt) ->
+decode(_, Mod, AppMod, Opts, #diameter_packet{header = Hdr} = Pkt) ->
     #diameter_header{cmd_code = CmdCode,
                      is_request = IsRequest,
                      is_error = IsError}
@@ -361,29 +347,33 @@ decode(_, Mod, #diameter_packet{header = Hdr} = Pkt) ->
                       Mod:msg_name(CmdCode, IsRequest)
               end,
 
-    decode_avps(MsgName, Mod, Pkt, collect_avps(Pkt));
+    decode_avps(MsgName, Mod, AppMod, Opts, Pkt, collect_avps(Pkt));
 
-decode(Id, Mod, Bin)
+decode(Id, Mod, AppMod, Opts, Bin)
   when is_binary(Bin) ->
-    decode(Id, Mod, #diameter_packet{header = decode_header(Bin), bin = Bin}).
+    decode(Id, Mod, AppMod, Opts, #diameter_packet{header = decode_header(Bin),
+                                                   bin = Bin}).
 
-%% decode_avps/4
+%% decode_avps/6
 
-decode_avps(MsgName, Mod, Pkt, {E, Avps}) ->
+decode_avps(MsgName, Mod, AppMod, Opts, Pkt, {E, Avps}) ->
     ?LOG(invalid_avp_length, Pkt#diameter_packet.header),
     #diameter_packet{errors = Failed}
         = P
-        = decode_avps(MsgName, Mod, Pkt, Avps),
+        = decode_avps(MsgName, Mod, AppMod, Opts, Pkt, Avps),
     P#diameter_packet{errors = [E | Failed]};
 
-decode_avps('', _, Pkt, Avps) ->  %% unknown message ...
+decode_avps('', _, _, _, Pkt, Avps) ->  %% unknown message ...
     ?LOG(unknown_message, Pkt#diameter_packet.header),
     Pkt#diameter_packet{avps = lists:reverse(Avps),
                         errors = [3001]};   %% DIAMETER_COMMAND_UNSUPPORTED
 %% msg = undefined identifies this case.
 
-decode_avps(MsgName, Mod, Pkt, Avps) ->  %% ... or not
-    {Rec, As, Errors} = Mod:decode_avps(MsgName, Avps),
+decode_avps(MsgName, Mod, AppMod, Opts, Pkt, Avps) ->  %% ... or not
+    {Rec, As, Errors} = Mod:decode_avps(MsgName,
+                                        Avps,
+                                        Opts#{dictionary => AppMod,
+                                              failed_avp => false}),
     ?LOGC([] /= Errors, decode_errors, Pkt#diameter_packet.header),
     Pkt#diameter_packet{msg = Rec,
                         errors = Errors,
@@ -399,14 +389,12 @@ decode_avps(MsgName, Mod, Pkt, Avps) ->  %% ... or not
 
 decode_header(<<Version:8,
                 MsgLength:24,
-                CmdFlags:1/binary,
+                R:1, P:1, E:1, T:1, _:4,
                 CmdCode:24,
                 ApplicationId:32,
                 HopByHopId:32,
                 EndToEndId:32,
                 _/binary>>) ->
-    <<R:1, P:1, E:1, T:1, _:4>>
-        = CmdFlags,
     %% 3588 (ch 3) says that reserved bits MUST be set to 0 and ignored
     %% by the receiver.
 
@@ -518,7 +506,7 @@ msg_id(#diameter_packet{header = #diameter_header{} = Hdr}) ->
 msg_id(#diameter_header{application_id = A,
                         cmd_code = C,
                         is_request = R}) ->
-    {A, C, if R -> 1; true -> 0 end};
+    {A, C, ?BIT(R)};
 
 msg_id(<<_:32, Rbit:1, _:7, CmdCode:24, ApplId:32, _/binary>>) ->
     {ApplId, CmdCode, Rbit}.
@@ -537,24 +525,14 @@ msg_id(<<_:32, Rbit:1, _:7, CmdCode:24, ApplId:32, _/binary>>) ->
  when Avp   :: #diameter_avp{},
       Error :: {5014, #diameter_avp{}}.
 
-collect_avps(#diameter_packet{bin = Bin}) ->
-    <<_:20/binary, Avps/binary>> = Bin,
-    collect_avps(Avps);
+collect_avps(#diameter_packet{bin = <<_:20/binary, Avps/binary>>}) ->
+    collect_avps(Avps, 0, []);
 
 collect_avps(Bin)
   when is_binary(Bin) ->
     collect_avps(Bin, 0, []).
 
-collect_avps(<<>>, _, Acc) ->
-    Acc;
-collect_avps(Bin, N, Acc) ->
-    try split_avp(Bin) of
-        {Rest, AVP} ->
-            collect_avps(Rest, N+1, [AVP#diameter_avp{index = N} | Acc])
-    catch
-        ?FAILURE(Error) ->
-            {Error, Acc}
-    end.
+%% collect_avps/3
 
 %%     0                   1                   2                   3
 %%     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ -568,32 +546,65 @@ collect_avps(Bin, N, Acc) ->
 %%    |    Data ...
 %%    +-+-+-+-+-+-+-+-+
 
-%% split_avp/1
+collect_avps(<<Code:32, V:1, M:1, P:1, _:5, Len:24, I:V/unit:32, Rest/binary>>,
+             N,
+             Acc) ->
+    collect_avps(Code,
+                 if 1 == V -> I; 0 == V -> undefined end,
+                 1 == M,
+                 1 == P,
+                 Len - 8 - V*4,  %% Might be negative, which ensures
+                 ?PAD(Len),      %%   failure of the Data match below.
+                 Rest,
+                 N,
+                 Acc);
 
-split_avp(Bin) ->
-    {Code, V, M, P, Len, HdrLen} = split_head(Bin),
-
-    <<_:HdrLen/binary, Rest/binary>> = Bin,
-    {Data, B} = split_data(Rest, Len - HdrLen),
-
-    {B, #diameter_avp{code = Code,
-                      vendor_id = V,
-                      is_mandatory = 1 == M,
-                      need_encryption = 1 == P,
-                      data = Data}}.
-
-%% split_head/1
-
-split_head(<<Code:32, 1:1, M:1, P:1, _:5, Len:24, V:32, _/binary>>) ->
-    {Code, V, M, P, Len, 12};
+collect_avps(<<>>, _, Acc) ->
+    Acc;
 
-split_head(<<Code:32, 0:1, M:1, P:1, _:5, Len:24, _/binary>>) ->
-    {Code, undefined, M, P, Len, 8};
+%% Header is truncated. pack_avp/1 will pad this at encode if sent in
+%% a Failed-AVP.
+collect_avps(Bin, _, Acc) ->
+    {{5014, #diameter_avp{data = Bin}}, Acc}.
+
+%% collect_avps/9
+
+%% Duplicate the diameter_avp creation in each branch below to avoid
+%% modifying the record, which profiling has shown to be a relatively
+%% costly part of building the list.
+
+collect_avps(Code, VendorId, M, P, Len, Pad, Rest, N, Acc) ->
+    case Rest of
+        <<Data:Len/binary, _:Pad/binary, T/binary>> ->
+            Avp = #diameter_avp{code = Code,
+                                vendor_id = VendorId,
+                                is_mandatory = M,
+                                need_encryption = P,
+                                data = Data,
+                                index = N},
+            collect_avps(T, N+1, [Avp | Acc]);
+        _ ->
+            %% Length in header points past the end of the message, or
+            %% doesn't span the header. As stated in the 6733 text
+            %% above, it's sufficient to return a zero-filled minimal
+            %% payload if this is a request. Do this (in cases that we
+            %% know the type) by inducing a decode failure and letting
+            %% the dictionary's decode (in diameter_gen) deal with it.
+            %%
+            %% Note that the extra bit can only occur in the trailing
+            %% AVP of a message or Grouped AVP, since a faulty AVP
+            %% Length is otherwise indistinguishable from a correct
+            %% one here, as we don't know the types of the AVPs being
+            %% extracted.
+            Avp = #diameter_avp{code = Code,
+                                vendor_id = VendorId,
+                                is_mandatory = M,
+                                need_encryption = P,
+                                data = {5014, Rest},
+                                index = N},
+            [Avp | Acc]
+    end.
 
-%% Header is truncated.
-split_head(Bin) ->
-    ?THROW({5014, #diameter_avp{data = Bin}}).
-%% Note that pack_avp/1 will pad this at encode if sent in a Failed-AVP.
 
 %% 3588:
 %%
@@ -626,35 +637,8 @@ split_head(Bin) ->
 %% the minimum value mean we might not know the identity of the AVP and
 %% (2) the last sentence covers this case.
 
-%% split_data/3
-
-split_data(Bin, Len) ->
-    Pad = (4 - (Len rem 4)) rem 4,
-
-    %% Len might be negative here, but that ensures the failure of the
-    %% binary match.
-
-    case Bin of
-        <<Data:Len/binary, _:Pad/binary, Rest/binary>> ->
-            {Data, Rest};
-        _ ->
-            %% Header length points past the end of the message, or
-            %% doesn't span the header. As stated in the 6733 text
-            %% above, it's sufficient to return a zero-filled minimal
-            %% payload if this is a request. Do this (in cases that we
-            %% know the type) by inducing a decode failure and letting
-            %% the dictionary's decode (in diameter_gen) deal with it.
-            %%
-            %% Note that the extra bit can only occur in the trailing
-            %% AVP of a message or Grouped AVP, since a faulty AVP
-            %% Length is otherwise indistinguishable from a correct
-            %% one here, since we don't know the types of the AVPs
-            %% being extracted.
-            {<<0:1, Bin/binary>>, <<>>}
-    end.
-
 %%% ---------------------------------------------------------------------------
-%%% # pack_avp/1
+%%% # pack_avp/2
 %%% ---------------------------------------------------------------------------
 
 %% The normal case here is data as an #diameter_avp{} list or an
@@ -664,104 +648,96 @@ split_data(Bin, Len) ->
 
 %% Decoded Grouped AVP with decoded components: ignore components
 %% since they're already encoded in the Grouped AVP.
-pack_avp([#diameter_avp{} = Grouped | _Components]) ->
-    pack_avp(Grouped);
+pack_avp([#diameter_avp{} = Grouped | _Components], Opts) ->
+    pack_avp(Grouped, Opts);
 
 %% Grouped AVP whose components need packing. It's intentional that
 %% this isn't equivalent to [Grouped | Components]: here the
 %% components need to be encoded before wrapping with the Grouped AVP,
 %% and the list is flat, nesting being accomplished in the data
 %% fields.
-pack_avp(#diameter_avp{data = [#diameter_avp{} | _] = Components} = Grouped) ->
-    pack_avp(Grouped#diameter_avp{data = encode_avps(Components)});
+pack_avp(#diameter_avp{data = [#diameter_avp{} | _] = Components}
+         = Grouped,
+         Opts) ->
+    pack_data(Grouped, encode_avps(Components, Opts));
 
 %% Data as a type/value tuple ...
-pack_avp(#diameter_avp{data = {Type, Value}} = A)
+pack_avp(#diameter_avp{data = {Type, Value}} = A, Opts)
   when is_atom(Type) ->
-    pack_avp(A#diameter_avp{data = diameter_types:Type(encode, Value)});
+    pack_data(A, diameter_types:Type(encode, Value, Opts));
 
 %% ... with a header in various forms ...
-pack_avp(#diameter_avp{data = {{_,_,_} = T, {Type, Value}}}) ->
-    pack_avp(T, iolist_to_binary(diameter_types:Type(encode, Value)));
+pack_avp(#diameter_avp{data = {T, {Type, Value}}}, Opts) ->
+    pack_data(T, diameter_types:Type(encode, Value, Opts));
 
-pack_avp(#diameter_avp{data = {{_,_,_} = T, Bin}})
-  when is_binary(Bin) ->
-    pack_avp(T, Bin);
+pack_avp(#diameter_avp{data = {T, Data}}, _) ->
+    pack_data(T, Data);
 
-pack_avp(#diameter_avp{data = {Dict, Name, Value}} = A) ->
-    {Code, _Flags, Vid} = Hdr = Dict:avp_header(Name),
-    {Name, Type} = Dict:avp_name(Code, Vid),
-    pack_avp(A#diameter_avp{data = {Hdr, {Type, Value}}});
+pack_avp(#diameter_avp{data = {Dict, Name, Data}}, Opts) ->
+    pack_data(Dict:avp_header(Name), Dict:avp(encode, Data, Name, Opts));
 
 %% ... with a truncated header ...
-pack_avp(#diameter_avp{code = undefined, data = B})
+pack_avp(#diameter_avp{code = undefined, data = B}, _)
   when is_binary(B) ->
     %% Reset the AVP Length of an AVP Header resulting from a 5014
     %% error. The RFC doesn't explicitly say to do this but the
     %% receiver can't correctly extract this and following AVP's
     %% without a correct length. On the downside, the header doesn't
-    %% reveal if the received header has been padded.
-    Pad = 8*header_length(B) - bit_size(B),
-    Len = size(<<H:5/binary, _:24, T/binary>> = <<B/binary, 0:Pad>>),
-    <<H/binary, Len:24, T/binary>>;
-
-%% ... when ignoring errors in Failed-AVP ...
-%% ... during a relay encode ...
-pack_avp(#diameter_avp{data = <<0:1, B/binary>>} = A) ->
-    pack_avp(A#diameter_avp{data = B});
-
-%% ... or as an iolist.
-pack_avp(#diameter_avp{code = Code,
-                       vendor_id = V,
-                       is_mandatory = M,
-                       need_encryption = P,
-                       data = Data}) ->
-    Flags = lists:foldl(fun flag_avp/2, 0, [{V /= undefined, 2#10000000},
-                                            {M, 2#01000000},
-                                            {P, 2#00100000}]),
-    pack_avp({Code, Flags, V}, iolist_to_binary(Data)).
-
-header_length(<<_:32, 1:1, _/bitstring>>) ->
+    %% reveal if the received header has been padded. Discard bytes
+    %% from the length header for this reason, to avoid creating a sub
+    %% binary for no useful reason.
+    Len = header_length(B),
+    Sz = min(5, size(B)),
+    <<B:Sz/binary, 0:(5-Sz)/unit:8, Len:24, 0:(Len-8)/unit:8>>;
+
+%% Ignoring errors in Failed-AVP or during a relay encode.
+pack_avp(#diameter_avp{data = {5014, Data}} = A, _) ->
+    pack_data(A, Data);
+
+pack_avp(#diameter_avp{data = Data} = A, _) ->
+    pack_data(A, Data).
+
+header_length(<<_:32, 1:1, _/bits>>) ->
     12;
 header_length(_) ->
     8.
 
-flag_avp({true, B}, F) ->
-    F bor B;
-flag_avp({false, _}, F) ->
-    F.
-
 %%% ---------------------------------------------------------------------------
-%%% # pack_avp/2
+%%% # pack_data/2
 %%% ---------------------------------------------------------------------------
 
-pack_avp({Code, Flags, VendorId}, Bin)
-  when is_binary(Bin) ->
-    Sz = size(Bin),
-    pack_avp(Code, Flags, VendorId, Sz, pad(Sz rem 4, Bin)).
-
-pad(0, Bin) ->
-    Bin;
-pad(N, Bin) ->
-    P = 8*(4-N),
-    <<Bin/binary, 0:P>>.
-%% Note that padding is not included in the length field as mandated by
-%% the RFC.
-
-%% pack_avp/5
+pack_data(#diameter_avp{code = Code,
+                        vendor_id = V,
+                        is_mandatory = M,
+                        need_encryption = P},
+          Data) ->
+    Flags = ?BIT(V /= undefined, 2#10000000)
+        bor ?BIT(M, 2#01000000)
+        bor ?BIT(P, 2#00100000),
+    pack(Code, Flags, V, Data);
+
+pack_data({Code, Flags, VendorId}, Data) ->
+    pack(Code, Flags, VendorId, Data).
+
+%% pack/4
+
+pack(Code, Flags, VendorId, Data) ->
+    Sz = iolist_size(Data),
+    pack(Code, Flags, Sz, VendorId, Data, ?PAD(Sz)).
+%% Padding is not included in the length field, as mandated by the RFC.
+
+%% pack/6
 %%
 %% Prepend the vendor id as required.
 
-pack_avp(Code, Flags, Vid, Sz, Bin)
+pack(Code, Flags, Sz, _Vid, Data, Pad)
   when 0 == Flags band 2#10000000 ->
-    undefined = Vid,  %% sanity check
-    pack_avp(Code, Flags, Sz, Bin);
+    pack(Code, Flags, Sz, 0, 0, Data, Pad);
 
-pack_avp(Code, Flags, Vid, Sz, Bin) ->
-    pack_avp(Code, Flags, Sz+4, <<Vid:32, Bin/binary>>).
+pack(Code, Flags, Sz, Vid, Data, Pad) ->
+    pack(Code, Flags, Sz+4, Vid, 1, Data, Pad).
 
-%% pack_avp/4
+%% pack/7
 
-pack_avp(Code, Flags, Sz, Bin) ->
-    Length = Sz + 8,
-    <<Code:32, Flags:8, Length:24, Bin/binary>>.
+pack(Code, Flags, Sz, VId, V, Data, Pad) ->
+    [<<Code:32, Flags:8, (8+Sz):24, VId:V/unit:32>>, Data, <<0:Pad/unit:8>>].
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index cea671f275..34018ae6d3 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -535,12 +535,12 @@ stop(SvcName) ->
 %% restrict applications so that that there's one while the service
 %% has many.
 
-add(SvcName, Type, Opts) ->
+add(SvcName, Type, Opts0) ->
     %% Ensure acceptable transport options. This won't catch all
     %% possible errors (faulty callbacks for example) but it catches
     %% many. diameter_service:merge_service/2 depends on usable
     %% capabilities for example.
-    ok = transport_opts(Opts),
+    Opts = transport_opts(Opts0),
 
     Ref = make_ref(),
     true = diameter_reg:add_new(?TRANSPORT_KEY(Ref)),
@@ -560,7 +560,17 @@ add(SvcName, Type, Opts) ->
     end.
 
 transport_opts(Opts) ->
-    lists:foreach(fun(T) -> opt(T) orelse ?THROW({invalid, T}) end, Opts).
+    lists:map(fun topt/1, Opts).
+
+topt(T) ->
+    case opt(T) of
+        {value, X} ->
+            X;
+        true ->
+            T;
+        false ->
+            ?THROW({invalid, T})
+    end.
 
 opt({transport_module, M}) ->
     is_atom(M);
@@ -600,8 +610,15 @@ opt({watchdog_timer, Tmo}) ->
 opt({watchdog_config, L}) ->
     is_list(L) andalso lists:all(fun wdopt/1, L);
 
-opt({spawn_opt, Opts}) ->
-    is_list(Opts);
+opt({spawn_opt, {M,F,A}})
+  when is_atom(M), is_atom(F), is_list(A) ->
+    true;
+opt({spawn_opt = K, Opts}) ->
+    if is_list(Opts) ->
+            {value, {K, spawn_opts(Opts)}};
+       true ->
+            false
+    end;
 
 opt({pool_size, N}) ->
     is_integer(N) andalso 0 < N;
@@ -676,7 +693,7 @@ stop_transport(SvcName, Refs) ->
 
 make_config(SvcName, Opts) ->
     AppOpts = [T || {application, _} = T <- Opts],
-    Apps = init_apps(AppOpts),
+    Apps = [init_app(T) || T <- AppOpts],
 
     [] == Apps andalso ?THROW(no_apps),
 
@@ -725,9 +742,13 @@ opt(incoming_maxlen, N)
   when 0 =< N, N < 1 bsl 24 ->
     N;
 
+opt(spawn_opt, {M,F,A} = T)
+  when is_atom(M), is_atom(F), is_list(A) ->
+    T;
+
 opt(spawn_opt, L)
   when is_list(L) ->
-    L;
+    spawn_opts(L);
 
 opt(K, false = B)
   when K == share_peers;
@@ -789,6 +810,9 @@ opt(sequence = K, F) ->
 opt(K, _) ->
     ?THROW({value, K}).
 
+spawn_opts(L) ->
+    [T || T <- L, T /= link, T /= monitor].
+
 sequence({H,N} = T)
   when 0 =< N, N =< 32, 0 =< H, 0 == H bsr (32-N) ->
     T;
@@ -822,10 +846,7 @@ encode_CER(Opts) ->
             ?THROW(Reason)
     end.
 
-init_apps(Opts) ->
-    lists:foldl(fun app_acc/2, [], lists:reverse(Opts)).
-
-app_acc({application, Opts} = T, Acc) ->
+init_app({application, Opts} = T) ->
     is_list(Opts) orelse ?THROW(T),
 
     [Dict, Mod] = get_opt([dictionary, module], Opts),
@@ -834,15 +855,14 @@ app_acc({application, Opts} = T, Acc) ->
     M = get_opt(call_mutates_state, Opts, false, [true]),
     A = get_opt(answer_errors, Opts, discard, [callback, report]),
     P = get_opt(request_errors, Opts, answer_3xxx, [answer, callback]),
-    [#diameter_app{alias = Alias,
-                   dictionary = Dict,
-                   id = cb(Dict, id),
-                   module = init_mod(Mod),
-                   init_state = ModS,
-                   mutable = M,
-                   options = [{answer_errors, A},
-                              {request_errors, P}]}
-     | Acc].
+    #diameter_app{alias = Alias,
+                  dictionary = Dict,
+                  id = cb(Dict, id),
+                  module = init_mod(Mod),
+                  init_state = ModS,
+                  mutable = M,
+                  options = [{answer_errors, A},
+                             {request_errors, P}]}.
 
 init_mod(#diameter_callback{} = R) ->
     init_mod([diameter_callback, R]);
diff --git a/lib/diameter/src/base/diameter_dict.erl b/lib/diameter/src/base/diameter_dict.erl
deleted file mode 100644
index 7db294a1b1..0000000000
--- a/lib/diameter/src/base/diameter_dict.erl
+++ /dev/null
@@ -1,154 +0,0 @@
-%%
-%% %CopyrightBegin%
-%%
-%% Copyright Ericsson AB 2010-2016. All Rights Reserved.
-%%
-%% Licensed under the Apache License, Version 2.0 (the "License");
-%% you may not use this file except in compliance with the License.
-%% You may obtain a copy of the License at
-%%
-%%     http://www.apache.org/licenses/LICENSE-2.0
-%%
-%% Unless required by applicable law or agreed to in writing, software
-%% distributed under the License is distributed on an "AS IS" BASIS,
-%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-%% See the License for the specific language governing permissions and
-%% limitations under the License.
-%%
-%% %CopyrightEnd%
-%%
-
-%%
-%% This module provide OTP's dict interface built on top of ets.
-%%
-%% Note that while the interface is the same as dict the semantics
-%% aren't quite. A Dict here is just a table identifier (although
-%% this fact can't be used if you want dict/ets-based implementations
-%% to be interchangeable) so changes made to the Dict modify the
-%% underlying table. For merge/3, the first argument table is modified.
-%%
-%% The underlying ets table implementing a dict is deleted when the
-%% process from which new() was invoked exits and the dict is only
-%% writable from this process.
-%%
-%% The reason for this is to be able to swap dict/ets-based
-%% implementations: the former is easier to debug, the latter is
-%% faster for larger tables. It's also just a nice interface even
-%% when there's no need for swapability.
-%%
-
--module(diameter_dict).
-
--export([append/3,
-         append_list/3,
-         erase/2,
-         fetch/2,
-         fetch_keys/1,
-         filter/2,
-         find/2,
-         fold/3,
-         from_list/1,
-         is_key/2,
-         map/2,
-         merge/3,
-         new/0,
-         store/3,
-         to_list/1,
-         update/3,
-         update/4,
-         update_counter/3]).
-
-%%% ----------------------------------------------------------
-%%% EXPORTED INTERNAL FUNCTIONS
-%%% ----------------------------------------------------------
-
-append(Key, Value, Dict) ->
-    append_list(Key, [Value], Dict).
-
-append_list(Key, ValueList, Dict)
-  when is_list(ValueList) ->
-    update(Key, fun(V) -> V ++ ValueList end, ValueList, Dict).
-
-erase(Key, Dict) ->
-    ets:delete(Dict, Key),
-    Dict.
-
-fetch(Key, Dict) ->
-    {ok, V} = find(Key, Dict),
-    V.
-
-fetch_keys(Dict) ->
-    ets:foldl(fun({K,_}, Acc) -> [K | Acc] end, [], Dict).
-
-filter(Pred, Dict) ->
-    lists:foreach(fun({K,V}) -> filter(Pred(K,V), K, Dict) end, to_list(Dict)),
-    Dict.
-
-find(Key, Dict) ->
-    case ets:lookup(Dict, Key) of
-        [{Key, V}] ->
-            {ok, V};
-        [] ->
-            error
-    end.
-
-fold(Fun, Acc0, Dict) ->
-    ets:foldl(fun({K,V}, Acc) -> Fun(K, V, Acc) end, Acc0, Dict).
-
-from_list(List) ->
-    lists:foldl(fun store/2, new(), List).
-
-is_key(Key, Dict) ->
-    ets:member(Dict, Key).
-
-map(Fun, Dict) ->
-    lists:foreach(fun({K,V}) -> store(K, Fun(K,V), Dict) end, to_list(Dict)),
-    Dict.
-
-merge(Fun, Dict1, Dict2) ->
-    fold(fun(K2,V2,_) ->
-                 update(K2, fun(V1) -> Fun(K2, V1, V2) end, V2, Dict1)
-         end,
-         Dict1,
-         Dict2).
-
-new() ->
-    ets:new(?MODULE, [set]).
-
-store(Key, Value, Dict) ->
-    store({Key, Value}, Dict).
-
-to_list(Dict) ->
-    ets:tab2list(Dict).
-
-update(Key, Fun, Dict) ->
-    store(Key, Fun(fetch(Key, Dict)), Dict).
-
-update(Key, Fun, Initial, Dict) ->
-    store(Key, map(Key, Fun, Dict, Initial), Dict).
-
-update_counter(Key, Increment, Dict)
-  when is_integer(Increment) ->
-    update(Key, fun(V) -> V + Increment end, Increment, Dict).
-
-%%% ---------------------------------------------------------
-%%% INTERNAL FUNCTIONS
-%%% ---------------------------------------------------------
-
-store({_,_} = T, Dict) ->
-    ets:insert(Dict, T),
-    Dict.
-
-filter(true, _, _) ->
-    ok;
-filter(false, K, Dict) ->
-    erase(K, Dict).
-
-map(Key, Fun, Dict, Error) ->
-    case find(Key, Dict) of
-        {ok, V} ->
-            Fun(V);
-        error ->
-            Error
-    end.
-
diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl
new file mode 100644
index 0000000000..e832832876
--- /dev/null
+++ b/lib/diameter/src/base/diameter_gen.erl
@@ -0,0 +1,709 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%%
+%% This file contains code that encode/decode modules generated by
+%% diameter_codegen.erl calls to implement the functionality. This
+%% code does most of the work, the generated code being kept simple.
+%%
+
+-module(diameter_gen).
+
+-export([encode_avps/3,
+         decode_avps/3,
+         grouped_avp/4,
+         empty_group/2,
+         empty/2]).
+
+-include_lib("diameter/include/diameter.hrl").
+
+-define(THROW(T), throw({?MODULE, T})).
+
+-type parent_name()   :: atom().  %% parent = Message or AVP
+-type parent_record() :: tuple(). %%
+-type avp_name()   :: atom().
+-type avp_record() :: tuple().
+-type avp_values() :: [{avp_name(), term()}].
+
+-type non_grouped_avp() :: #diameter_avp{}.
+-type grouped_avp() :: nonempty_improper_list(#diameter_avp{}, [avp()]).
+-type avp() :: non_grouped_avp() | grouped_avp().
+
+%% ---------------------------------------------------------------------------
+%% # encode_avps/3
+%% ---------------------------------------------------------------------------
+
+-spec encode_avps(parent_name(), parent_record() | avp_values(), map())
+   -> iolist()
+    | no_return().
+
+encode_avps(Name, Vals, #{module := Mod} = Opts) ->
+    try
+        encode(Name, Vals, Opts, Mod)
+    catch
+        throw: {?MODULE, Reason} ->
+            diameter_lib:log({encode, error},
+                             ?MODULE,
+                             ?LINE,
+                             {Reason, Name, Vals, Mod}),
+            erlang:error(list_to_tuple(Reason ++ [Name]));
+        error: Reason ->
+            Stack = erlang:get_stacktrace(),
+            diameter_lib:log({encode, failure},
+                             ?MODULE,
+                             ?LINE,
+                             {Reason, Name, Vals, Mod, Stack}),
+            erlang:error({encode_failure, Reason, Name, Stack})
+    end.
+
+%% encode/4
+
+encode(Name, Vals, #{ordered_encode := false} = Opts, Mod)
+  when is_list(Vals) ->
+    lists:map(fun({F,V}) -> encode(Name, F, V, Opts, Mod) end, Vals);
+
+encode(Name, Vals, Opts, Mod)
+  when is_list(Vals) ->
+    encode(Name, Mod:'#set-'(Vals, newrec(Mod, Name)), Opts, Mod);
+
+encode(Name, Rec, Opts, Mod) ->
+    [encode(Name, F, V, Opts, Mod) || {F,V} <- Mod:'#get-'(Rec)].
+
+%% encode/5
+
+encode(Name, AvpName, Values, Opts, Mod) ->
+    enc(Name, AvpName, Mod:avp_arity(Name, AvpName), Values, Opts, Mod).
+
+%% enc/6
+
+enc(_, AvpName, 1, undefined, _, _) ->
+    ?THROW([mandatory_avp_missing, AvpName]);
+
+enc(Name, AvpName, 1, Value, Opts, Mod) ->
+    enc(Name, AvpName, [Value], Opts, Mod);
+
+enc(_, _, {0,_}, [], _, _) ->
+    [];
+
+enc(_, AvpName, _, T, _, _)
+  when not is_list(T) ->
+    ?THROW([repeated_avp_as_non_list, AvpName, T]);
+
+enc(_, AvpName, {Min, _}, L, _, _)
+  when length(L) < Min ->
+    ?THROW([repeated_avp_insufficient_arity, AvpName, Min, L]);
+
+enc(_, AvpName, {_, Max}, L, _, _)
+  when Max < length(L) ->
+    ?THROW([repeated_avp_excessive_arity, AvpName, Max, L]);
+
+enc(Name, AvpName, _, Values, Opts, Mod) ->
+    enc(Name, AvpName, Values, Opts, Mod).
+
+%% enc/5
+
+enc(Name, 'AVP', Values, Opts, Mod) ->
+    [enc_AVP(Name, A, Opts, Mod) || A <- Values];
+
+enc(_, AvpName, Values, Opts, Mod) ->
+    enc(AvpName, Values, Opts, Mod).
+
+%% enc/4
+
+enc(AvpName, Values, Opts, Mod) ->
+    H = Mod:avp_header(AvpName),
+    [diameter_codec:pack_data(H, Mod:avp(encode, V, AvpName, Opts))
+     || V <- Values].
+
+%% enc_AVP/4
+
+%% No value: assume AVP data is already encoded. The normal case will
+%% be when this is passed back from #diameter_packet.errors as a
+%% consequence of a failed decode. Any AVP can be encoded this way
+%% however, which side-steps any arity checks for known AVP's and
+%% could potentially encode something unfortunate.
+enc_AVP(_, #diameter_avp{value = undefined} = A, Opts, _) ->
+    diameter_codec:pack_avp(A, Opts);
+
+%% Missing name for value encode.
+enc_AVP(_, #diameter_avp{name = N, value = V}, _, _)
+  when N == undefined;
+       N == 'AVP' ->
+    ?THROW([value_with_nameless_avp, N, V]);
+
+%% Or not. Ensure that 'AVP' is the appropriate field. Note that if we
+%% don't know this AVP at all then the encode will fail.
+enc_AVP(Name, #diameter_avp{name = AvpName, value = Data}, Opts, Mod) ->
+    0 == Mod:avp_arity(Name, AvpName)
+        orelse ?THROW([known_avp_as_AVP, Name, AvpName, Data]),
+    enc(AvpName, [Data], Opts, Mod);
+
+%% The backdoor ...
+enc_AVP(_, {AvpName, Value}, Opts, Mod) ->
+    enc(AvpName, [Value], Opts, Mod);
+
+%% ... and the side door.
+enc_AVP(_Name, {_Dict, _AvpName, _Data} = T, Opts, _) ->
+    diameter_codec:pack_avp(#diameter_avp{data = T}, Opts).
+
+%% ---------------------------------------------------------------------------
+%% # decode_avps/3
+%% ---------------------------------------------------------------------------
+
+-spec decode_avps(parent_name(), [#diameter_avp{}], map())
+   -> {parent_record(), [avp()], Failed}
+ when Failed :: [{5000..5999, #diameter_avp{}}].
+
+decode_avps(Name, Recs, #{module := Mod} = Opts) ->
+    {Avps, {Rec, Failed}}
+        = mapfoldl(fun(T,A) -> decode(Name, Opts, Mod, T, A) end,
+                   {newrec(Mod, Name), []},
+                   Recs),
+    {Rec, Avps, Failed ++ missing(Rec, Name, Failed, Opts, Mod)}.
+%% Append 5005 errors so that errors are reported in the order
+%% encountered. Failed-AVP should typically contain the first
+%% encountered error accordg to the RFC.
+
+%% mapfoldl/3
+%%
+%% Like lists:mapfoldl/3, but don't reverse the list.
+
+mapfoldl(F, Acc, List) ->
+    mapfoldl(F, Acc, List, []).
+
+mapfoldl(F, Acc0, [T|Rest], List) ->
+    {B, Acc} = F(T, Acc0),
+    mapfoldl(F, Acc, Rest, [B|List]);
+mapfoldl(_, Acc, [], List) ->
+    {List, Acc}.
+
+%% 3588:
+%%
+%%   DIAMETER_MISSING_AVP               5005
+%%      The request did not contain an AVP that is required by the Command
+%%      Code definition.  If this value is sent in the Result-Code AVP, a
+%%      Failed-AVP AVP SHOULD be included in the message.  The Failed-AVP
+%%      AVP MUST contain an example of the missing AVP complete with the
+%%      Vendor-Id if applicable.  The value field of the missing AVP
+%%      should be of correct minimum length and contain zeros.
+
+missing(Rec, Name, Failed, Opts, Mod) ->
+    Avps = lists:foldl(fun({_, #diameter_avp{code = C, vendor_id = V}}, A) ->
+                               maps:put({C,V}, true, A)
+                       end,
+                       maps:new(),
+                       Failed),
+    missing(Mod:avp_arity(Name), tl(tuple_to_list(Rec)), Avps, Opts, Mod, []).
+
+missing([{Name, Arity} | As], [Value | Vs], Avps, Opts, Mod, Acc) ->
+    missing(As,
+            Vs,
+            Avps,
+            Opts,
+            Mod,
+            case
+                [H || missing_arity(Arity, Value),
+                      {C,_,V} = H <- [Mod:avp_header(Name)],
+                      not maps:is_key({C,V}, Avps)]
+            of
+                [H] ->
+                    [{5005, empty_avp(Name, H, Opts, Mod)} | Acc];
+                [] ->
+                    Acc
+            end);
+
+missing([], [], _, _, _, Acc) ->
+    Acc.
+
+%% Maximum arities have already been checked in building the record.
+
+missing_arity(1, V) ->
+    V == undefined;
+missing_arity({0, _}, _) ->
+    false;
+missing_arity({1, _}, L) ->
+    [] == L;
+missing_arity({Min, _}, L) ->
+    not has_prefix(Min, L).
+
+%% Compare a non-negative integer and the length of a list without
+%% computing the length.
+has_prefix(0, _) ->
+    true;
+has_prefix(_, []) ->
+    false;
+has_prefix(N, [_|L]) ->
+    has_prefix(N-1, L).
+
+%% empty_avp/4
+
+empty_avp(Name, {Code, Flags, VId}, Opts, Mod) ->
+    {Name, Type} = Mod:avp_name(Code, VId),
+    #diameter_avp{name = Name,
+                  code = Code,
+                  vendor_id = VId,
+                  is_mandatory = 0 /= (Flags band 2#01000000),
+                  need_encryption = 0 /= (Flags band 2#00100000),
+                  data = Mod:empty_value(Name, Opts),
+                  type = Type}.
+
+%% 3588, ch 7:
+%%
+%%   The Result-Code AVP describes the error that the Diameter node
+%%   encountered in its processing.  In case there are multiple errors,
+%%   the Diameter node MUST report only the first error it encountered
+%%   (detected possibly in some implementation dependent order).  The
+%%   specific errors that can be described by this AVP are described in
+%%   the following section.
+
+%% decode/5
+
+decode(Name,
+       Opts,
+       Mod,
+       #diameter_avp{code = Code, vendor_id = Vid}
+       = Avp,
+       Acc) ->
+    decode(Name, Opts, Mod, Mod:avp_name(Code, Vid), Avp, Acc).
+
+%% decode/6
+
+%% AVP not in dictionary.
+decode(Name, Opts, Mod, 'AVP', Avp, Acc) ->
+    decode_AVP(Name, Avp, Opts, Mod, Acc);
+
+%% 6733, 4.4:
+%%
+%%   Receivers of a Grouped AVP that does not have the 'M' (mandatory)
+%%   bit set and one or more of the encapsulated AVPs within the group
+%%   has the 'M' (mandatory) bit set MAY simply be ignored if the
+%%   Grouped AVP itself is unrecognized. The rule applies even if the
+%%   encapsulated AVP with its 'M' (mandatory) bit set is further
+%%   encapsulated within other sub-groups, i.e., other Grouped AVPs
+%%   embedded within the Grouped AVP.
+%%
+%% The first sentence is slightly mangled, but take it to mean this:
+%%
+%%   An unrecognized AVP of type Grouped that does not set the 'M' bit
+%%   MAY be ignored even if one of its encapsulated AVPs sets the 'M'
+%%   bit.
+%%
+%% The text above is a change from RFC 3588, which instead says this:
+%%
+%%   Further, if any of the AVPs encapsulated within a Grouped AVP has
+%%   the 'M' (mandatory) bit set, the Grouped AVP itself MUST also
+%%   include the 'M' bit set.
+%%
+%% Both of these texts have problems. If the AVP is unknown then its
+%% type is unknown since the type isn't sent over the wire, so the
+%% 6733 text becomes a non-statement: don't know that the AVP not
+%% setting the M-bit is of type Grouped, therefore can't know that its
+%% data consists of encapsulated AVPs, therefore can't but ignore that
+%% one of these might set the M-bit. It should be no worse if we know
+%% the AVP to have type Grouped.
+%%
+%% Similarly, for the 3588 text: if we receive an AVP that doesn't set
+%% the M-bit and don't know that the AVP has type Grouped then we
+%% can't realize that its data contains an AVP that sets the M-bit, so
+%% can't regard the AVP as erroneous on this account. Again, it should
+%% be no worse if the type is known to be Grouped, but in this case
+%% the RFC forces us to regard the AVP as erroneous. This is
+%% inconsistent, and the 3588 text has never been enforced.
+%%
+%% So, if an AVP doesn't set the M-bit then we're free to ignore it,
+%% regardless of the AVP's type. If we know the type to be Grouped
+%% then we must ignore the M-bit on an encapsulated AVP. That means
+%% packing such an encapsulated AVP into an 'AVP' field if need be,
+%% not regarding the lack of a specific field as an error as is
+%% otherwise the case. (The lack of an AVP-specific field being how we
+%% defined the RFC's "unrecognized", which is slightly stronger than
+%% "not defined".)
+
+decode(Name, Opts0, Mod, {AvpName, Type}, Avp, Acc) ->
+    #diameter_avp{data = Data, is_mandatory = M}
+        = Avp,
+
+    %% Whether or not to ignore an M-bit on an encapsulated AVP, or on
+    %% all AVPs with the service_opt() strict_mbit.
+    Opts1 = set_strict(Type, M, Opts0),
+
+    %% Whether or not we're decoding within Failed-AVP and should
+    %% ignore decode errors.
+    #{dictionary := AppMod, failed_avp := Failed}
+        = Opts
+        = set_failed(Name, Opts1), %% Not AvpName or else a failed Failed-AVP
+                                   %% decode is packed into 'AVP'.
+
+    %% Reset the dictionary for best-effort decode of Failed-AVP.
+    DecMod = if Failed ->
+                     AppMod;
+                true ->
+                     Mod
+             end,
+
+    %% On decode, a Grouped AVP is represented as a #diameter_avp{}
+    %% list with AVP as head and component AVPs as tail. On encode,
+    %% data can be a list of component AVPs.
+
+    try avp_decode(Data, AvpName, Opts, DecMod, Mod) of
+        {Rec, As} when Type == 'Grouped' ->
+            A = Avp#diameter_avp{name = AvpName,
+                                 value = Rec,
+                                 type = Type},
+            {[A|As], pack_avp(Name, A, Opts, Mod, Acc)};
+
+        V when Type /= 'Grouped' ->
+            A = Avp#diameter_avp{name = AvpName,
+                                 value = V,
+                                 type = Type},
+            {A, pack_avp(Name, A, Opts, Mod, Acc)}
+    catch
+        throw: {?MODULE, {grouped, Error, ComponentAvps}} ->
+            decode_error(Name,
+                         Error,
+                         ComponentAvps,
+                         Opts,
+                         Mod,
+                         Avp#diameter_avp{name = AvpName,
+                                          data = trim(Avp#diameter_avp.data),
+                                          type = Type},
+                         Acc);
+
+        error: Reason ->
+            decode_error(Name,
+                         Reason,
+                         Opts,
+                         Mod,
+                         Avp#diameter_avp{name = AvpName,
+                                          data = trim(Avp#diameter_avp.data),
+                                          type = Type},
+                         Acc)
+    end.
+
+%% avp_decode/5
+
+avp_decode(Data, AvpName, Opts, Mod, Mod) ->
+    Mod:avp(decode, Data, AvpName, Opts);
+
+avp_decode(Data, AvpName, Opts, Mod, _) ->
+    Mod:avp(decode, Data, AvpName, Opts, Mod).
+
+%% trim/1
+%%
+%% Remove any extra bit that was added in diameter_codec to induce a
+%% 5014 error.
+
+trim(#diameter_avp{data = Data} = Avp) ->
+    Avp#diameter_avp{data = trim(Data)};
+
+trim({5014, Bin}) ->
+    Bin;
+
+trim(Avps)
+  when is_list(Avps) ->
+    lists:map(fun trim/1, Avps);
+
+trim(Avp) ->
+    Avp.
+
+%% decode_error/7
+
+decode_error(Name, [_ | Rec], _, #{failed_avp := true} = Opts, Mod, Avp, Acc) ->
+    decode_AVP(Name, Avp#diameter_avp{value = Rec}, Opts, Mod, Acc);
+
+decode_error(Name, _, _, #{failed_avp := true} = Opts, Mod, Avp, Acc) ->
+    decode_AVP(Name, Avp, Opts, Mod, Acc);
+
+decode_error(_, [Error | _], ComponentAvps, _, _, Avp, Acc) ->
+    decode_error(Error, Avp, Acc, ComponentAvps);
+
+decode_error(_, Error, ComponentAvps, _, _, Avp, Acc) ->
+    decode_error(Error, Avp, Acc, ComponentAvps).
+
+%% decode_error/5
+
+decode_error(Name, _Reason, #{failed_avp := true} = Opts, Mod, Avp, Acc) ->
+    decode_AVP(Name, Avp, Opts, Mod, Acc);
+
+decode_error(Name, Reason, Opts, Mod, Avp, {Rec, Failed}) ->
+    Stack = diameter_lib:get_stacktrace(),
+    diameter_lib:log(decode_error,
+                     ?MODULE,
+                     ?LINE,
+                     {Reason, Name, Avp#diameter_avp.name, Mod, Stack}),
+    {Avp, {Rec, [rc(Reason, Avp, Opts, Mod) | Failed]}}.
+
+%% decode_error/4
+
+decode_error({RC, ErrorData}, Avp, {Rec, Failed}, ComponentAvps) ->
+    E = Avp#diameter_avp{data = [ErrorData]},
+    {[Avp | trim(ComponentAvps)], {Rec, [{RC, E} | Failed]}}.
+
+%% set_strict/3
+
+%% Set false as soon as we see a Grouped AVP that doesn't set the
+%% M-bit, to ignore the M-bit on an encapsulated AVP.
+set_strict('Grouped', false = M, #{strict_mbit := true} = Opts) ->
+    Opts#{strict_mbit := M};
+set_strict(_, _, Opts) ->
+    Opts.
+
+%% set_failed/2
+%%
+%% Set true as soon as we see Failed-AVP. Matching on 'Failed-AVP'
+%% assumes that this is the RFC AVP. Strictly, this doesn't need to be
+%% the case.
+
+set_failed('Failed-AVP', #{failed_avp := false} = Opts) ->
+    Opts#{failed_avp := true};
+set_failed(_, Opts) ->
+    Opts.
+
+%% decode_AVP/5
+%%
+%% Don't know this AVP: see if it can be packed in an 'AVP' field
+%% undecoded. Note that the type field is 'undefined' in this case.
+
+decode_AVP(Name, Avp, Opts, Mod, Acc) ->
+    {trim(Avp), pack_AVP(Name, Avp, Opts, Mod, Acc)}.
+
+%% rc/2
+
+%% diameter_types will raise an error of this form to communicate
+%% DIAMETER_INVALID_AVP_LENGTH (5014). A module specified to a
+%% @custom_types tag in a dictionary file can also raise an error of
+%% this form.
+rc({'DIAMETER', 5014 = RC, _}, #diameter_avp{name = AvpName} = Avp, Opts, Mod) ->
+    {RC, Avp#diameter_avp{data = Mod:empty_value(AvpName, Opts)}};
+
+%% 3588:
+%%
+%%   DIAMETER_INVALID_AVP_VALUE         5004
+%%      The request contained an AVP with an invalid value in its data
+%%      portion.  A Diameter message indicating this error MUST include
+%%      the offending AVPs within a Failed-AVP AVP.
+rc(_, Avp, _, _) ->
+    {5004, Avp}.
+
+%% pack_avp/5
+
+pack_avp(Name, #diameter_avp{name = AvpName} = Avp, Opts, Mod, Acc) ->
+    pack_avp(Name, Mod:avp_arity(Name, AvpName), Avp, Opts, Mod, Acc).
+
+%% pack_avp/6
+
+pack_avp(Name, 0, Avp, Opts, Mod, Acc) ->
+    pack_AVP(Name, Avp, Opts, Mod, Acc);
+
+pack_avp(_, Arity, #diameter_avp{name = AvpName} = Avp, _Opts, Mod, Acc) ->
+    pack(Arity, AvpName, Avp, Mod, Acc).
+
+%% pack_AVP/5
+
+%% Length failure was induced because of a header/payload length
+%% mismatch. The AVP Length is reset to match the received data if
+%% this AVP is encoded in an answer message, since the length is
+%% computed.
+%%
+%% Data is a truncated header if command_code = undefined, otherwise
+%% payload bytes. The former is padded to the length of a header if
+%% the AVP reaches an outgoing encode in diameter_codec.
+%%
+%% RFC 6733 says that an AVP returned with 5014 can contain a minimal
+%% payload for the AVP's type, but in this case we don't know the
+%% type.
+
+pack_AVP(_, #diameter_avp{data = {5014 = RC, Data}} = Avp, _, _, Acc) ->
+    {Rec, Failed} = Acc,
+    {Rec, [{RC, Avp#diameter_avp{data = Data}} | Failed]};
+
+pack_AVP(Name, Avp, Opts, Mod, Acc) ->
+    pack_arity(Name, pack_arity(Name, Opts, Mod, Avp), Avp, Mod, Acc).
+
+%% pack_arity/5
+
+pack_arity(_, 0, #diameter_avp{is_mandatory = M} = Avp, _, Acc) ->
+    {Rec, Failed} = Acc,
+    {Rec, [{if M -> 5001; true -> 5008 end, Avp} | Failed]};
+
+pack_arity(_, Arity, Avp, Mod, Acc) ->
+    pack(Arity, 'AVP', Avp, Mod, Acc).
+
+%% Give Failed-AVP special treatment since (1) it'll contain any
+%% unrecognized mandatory AVP's and (2) the RFC 3588 grammar failed to
+%% allow for Failed-AVP in an answer-message.
+
+pack_arity(Name,
+           #{strict_mbit := Strict,
+             failed_avp := Failed},
+           Mod,
+           #diameter_avp{is_mandatory = M,
+                         name = AvpName}) ->
+
+    %% Not testing just Name /= 'Failed-AVP' means we're changing the
+    %% packing of AVPs nested within Failed-AVP, but the point of
+    %% ignoring errors within Failed-AVP is to decode as much as
+    %% possible, and failing because a mandatory AVP couldn't be
+    %% packed into a dedicated field defeats that point.
+
+    if Failed == true;
+       Name == 'Failed-AVP';
+       Name == 'answer-message', AvpName == 'Failed-AVP';
+       not M;
+       not Strict ->
+            Mod:avp_arity(Name, 'AVP');
+       true ->
+            0
+    end.
+
+%% 3588:
+%%
+%%   DIAMETER_AVP_UNSUPPORTED           5001
+%%      The peer received a message that contained an AVP that is not
+%%      recognized or supported and was marked with the Mandatory bit.  A
+%%      Diameter message with this error MUST contain one or more Failed-
+%%      AVP AVP containing the AVPs that caused the failure.
+%%
+%%   DIAMETER_AVP_NOT_ALLOWED           5008
+%%      A message was received with an AVP that MUST NOT be present.  The
+%%      Failed-AVP AVP MUST be included and contain a copy of the
+%%      offending AVP.
+
+%% pack/5
+
+pack(Arity, FieldName, Avp, Mod, {Rec, _} = Acc) ->
+    pack(Mod:'#get-'(FieldName, Rec), Arity, FieldName, Avp, Mod, Acc).
+
+%% pack/6
+
+pack(undefined, 1, 'AVP' = F, Avp, Mod, {Rec, Failed}) ->  %% unlikely
+    {Mod:'#set-'({F, Avp}, Rec), Failed};
+
+pack(undefined, 1, F, #diameter_avp{value = V}, Mod, {Rec, Failed}) ->
+    {Mod:'#set-'({F, V}, Rec), Failed};
+
+%% 3588:
+%%
+%%   DIAMETER_AVP_OCCURS_TOO_MANY_TIMES 5009
+%%      A message was received that included an AVP that appeared more
+%%      often than permitted in the message definition.  The Failed-AVP
+%%      AVP MUST be included and contain a copy of the first instance of
+%%      the offending AVP that exceeded the maximum number of occurrences
+%%
+
+pack(_, 1, _, Avp, _, {Rec, Failed}) ->
+    {Rec, [{5009, Avp} | Failed]};
+
+pack(L, {_, Max}, F, Avp, Mod, {Rec, Failed}) ->
+    case '*' /= Max andalso has_prefix(Max+1, L) of
+        true ->
+            {Rec, [{5009, Avp} | Failed]};
+        false when F == 'AVP' ->
+            {Mod:'#set-'({F, [Avp | L]}, Rec), Failed};
+        false ->
+            {Mod:'#set-'({F, [Avp#diameter_avp.value | L]}, Rec), Failed}
+    end.
+
+%% ---------------------------------------------------------------------------
+%% # grouped_avp/3
+%% ---------------------------------------------------------------------------
+
+-spec grouped_avp(decode, avp_name(), binary() | {5014, binary()}, term())
+   -> {avp_record(), [avp()]};
+                 (encode, avp_name(), avp_record() | avp_values(), term())
+   -> iolist()
+    | no_return().
+
+%% Length error induced by diameter_codec:collect_avps/1: the AVP
+%% length in the header was too short (insufficient for the extracted
+%% header) or too long (past the end of the message). An empty payload
+%% is sufficient according to the RFC text for 5014.
+grouped_avp(decode, _Name, {5014 = RC, _Bin}, _) ->
+    ?THROW({grouped, {RC, []}, []});
+
+grouped_avp(decode, Name, Data, Opts) ->
+    grouped_decode(Name, diameter_codec:collect_avps(Data), Opts);
+
+grouped_avp(encode, Name, Data, Opts) ->
+    encode_avps(Name, Data, Opts).
+
+%% grouped_decode/2
+%%
+%% Note that Grouped is the only AVP type that doesn't just return a
+%% decoded value, also returning the list of component diameter_avp
+%% records.
+
+%% Length error in trailing component AVP.
+grouped_decode(_Name, {Error, Acc}, _) ->
+    {5014, Avp} = Error,
+    ?THROW({grouped, Error, [Avp | Acc]});
+
+%% 7.5.  Failed-AVP AVP
+
+%%    In the case where the offending AVP is embedded within a Grouped AVP,
+%%    the Failed-AVP MAY contain the grouped AVP, which in turn contains
+%%    the single offending AVP.  The same method MAY be employed if the
+%%    grouped AVP itself is embedded in yet another grouped AVP and so on.
+%%    In this case, the Failed-AVP MAY contain the grouped AVP hierarchy up
+%%    to the single offending AVP.  This enables the recipient to detect
+%%    the location of the offending AVP when embedded in a group.
+
+%% An error in decoding a component AVP throws the first faulty
+%% component, which the catch in d/3 wraps in the Grouped AVP in
+%% question. A partially decoded record is only used when ignoring
+%% errors in Failed-AVP.
+grouped_decode(Name, ComponentAvps, Opts) ->
+    {Rec, Avps, Es} = decode_avps(Name, ComponentAvps, Opts),
+    [] == Es orelse ?THROW({grouped, [{_,_} = hd(Es) | Rec], Avps}),
+    {Rec, Avps}.
+
+%% ---------------------------------------------------------------------------
+%% # empty_group/2
+%% ---------------------------------------------------------------------------
+
+empty_group(Name, #{module := Mod} = Opts) ->
+    list_to_binary([z(F, A, Opts, Mod) || {F,A} <- Mod:avp_arity(Name)]).
+
+z(Name, 1, Opts, Mod) ->
+    z(Name, Opts, Mod);
+z(_, {0,_}, _, _) ->
+    [];
+z(Name, {Min, _}, Opts, Mod) ->
+    binary:copy(z(Name, Opts, Mod), Min).
+
+z('AVP', _, _) ->
+    <<0:64>>;  %% minimal header
+z(Name, Opts, Mod) ->
+    Bin = diameter_codec:pack_data(Mod:avp_header(Name),
+                                   Mod:empty_value(Name, Opts)),
+    Sz = iolist_size(Bin),
+    <<0:Sz/unit:8>>.
+
+%% ---------------------------------------------------------------------------
+%% # empty/2
+%% ---------------------------------------------------------------------------
+
+empty(Name, #{module := Mod} = Opts) ->
+    Mod:avp(encode, zero, Name, Opts).
+
+%% ------------------------------------------------------------------------------
+
+newrec(Mod, Name) ->
+    Mod:'#new-'(Mod:name2rec(Name)).
diff --git a/lib/diameter/src/base/diameter_lib.erl b/lib/diameter/src/base/diameter_lib.erl
index 3928769b5e..58b9a29812 100644
--- a/lib/diameter/src/base/diameter_lib.erl
+++ b/lib/diameter/src/base/diameter_lib.erl
@@ -37,7 +37,6 @@
          ipaddr/1,
          spawn_opts/2,
          wait/1,
-         fold_tuple/3,
          fold_n/3,
          for_n/2,
          log/4]).
@@ -341,36 +340,6 @@ down(MRef)
     receive {'DOWN', MRef, process, _, _} = T -> T end.
 
 %% ---------------------------------------------------------------------------
-%% # fold_tuple/3
-%% ---------------------------------------------------------------------------
-
--spec fold_tuple(N, T0, T)
-   -> tuple()
- when N  :: pos_integer(),
-      T0 :: tuple(),
-      T  :: tuple()
-          | undefined.
-
-%% Replace fields in T0 by those of T starting at index N, unless the
-%% new value is 'undefined'.
-%%
-%% eg. fold_tuple(2, Hdr, #diameter_header{end_to_end_id = 42})
-
-fold_tuple(_, T, undefined) ->
-    T;
-
-fold_tuple(N, T0, T1) ->
-    {_, T} = lists:foldl(fun(V, {I,_} = IT) -> {I+1, ft(V, IT)} end,
-                         {N, T0},
-                         lists:nthtail(N-1, tuple_to_list(T1))),
-    T.
-
-ft(undefined, {_, T}) ->
-    T;
-ft(Value, {Idx, T}) ->
-    setelement(Idx, T, Value).
-
-%% ---------------------------------------------------------------------------
 %% # fold_n/3
 %% ---------------------------------------------------------------------------
 
diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 601e48e817..1b0dc417e5 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -128,6 +128,10 @@
                        %% outgoing DPR; boolean says whether or not
                        %% the request was sent explicitly with
                        %% diameter:call/4.
+         codec :: #{string_decode := boolean(),
+                    strict_mbit := boolean(),
+                    rfc := 3588 | 6733,
+                    ordered_encode := false},
          strict :: boolean(),
          ack = false :: boolean(),
          length_errors :: exit | handle | discard,
@@ -160,10 +164,7 @@
 %% # start/3
 %% ---------------------------------------------------------------------------
 
--spec start(T, [Opt], {[diameter:service_opt()],
-                       [node()],
-                       module(),
-                       #diameter_service{}})
+-spec start(T, [Opt], {map(), [node()], module(), #diameter_service{}})
    -> {reference(), pid()}
  when T   :: {connect|accept, diameter:transport_ref()},
       Opt :: diameter:transport_opt().
@@ -222,9 +223,10 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) ->
     erlang:monitor(process, WPid),
     wait(Ack, WPid),
     diameter_stats:reg(Ref),
-    diameter_codec:setopts([{common_dictionary, Dict0} | SvcOpts]),
-    {_,_} = Mask = proplists:get_value(sequence, SvcOpts),
-    Maxlen = proplists:get_value(incoming_maxlen, SvcOpts, 16#FFFFFF),
+
+    #{sequence := Mask, incoming_maxlen := Maxlen}
+        = SvcOpts,
+
     {[Cs,Ds], Rest} = proplists:split(Opts, [capabilities_cb, disconnect_cb]),
     putr(?CB_KEY, {Ref, [F || {_,F} <- Cs]}),
     putr(?DPR_KEY, [F || {_, F} <- Ds]),
@@ -250,7 +252,12 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) ->
            service = svc(Svc, Addrs),
            length_errors = LengthErr,
            strict = Strictness,
-           incoming_maxlen = Maxlen}.
+           incoming_maxlen = Maxlen,
+           codec = maps:with([string_decode,
+                              strict_mbit,
+                              rfc,
+                              ordered_encode],
+                             SvcOpts#{ordered_encode => false})}.
 %% The transport returns its local ip addresses so that different
 %% transports on the same service can use different local addresses.
 %% The local addresses are put into Host-IP-Address avps here when
@@ -590,7 +597,8 @@ send_CER(#state{state = {'Wait-Conn-Ack', Tmo},
                 mode = {connect, Remote},
                 service = #diameter_service{capabilities = LCaps},
                 transport = TPid,
-                dictionary = Dict}
+                dictionary = Dict,
+                codec = Opts}
          = S) ->
     OH = LCaps#diameter_caps.origin_host,
     req_send_CER(OH, Remote)
@@ -600,7 +608,7 @@ send_CER(#state{state = {'Wait-Conn-Ack', Tmo},
     #diameter_packet{header = #diameter_header{end_to_end_id = Eid,
                                                hop_by_hop_id = Hid}}
         = Pkt
-        = encode(CER, Dict),
+        = encode(CER, Opts, Dict),
     incr(send, Pkt, Dict),
     send(TPid, Pkt),
     ?LOG(send, 'CER'),
@@ -629,15 +637,15 @@ build_CER(#state{service = #diameter_service{capabilities = LCaps},
     {ok, CER} = diameter_capx:build_CER(LCaps, Dict),
     CER.
 
-%% encode/2
+%% encode/3
 
-encode(Rec, Dict) ->
+encode(Rec, Opts, Dict) ->
     Seq = diameter_session:sequence({_,_} = getr(?SEQUENCE_KEY)),
     Hdr = #diameter_header{version = ?DIAMETER_VERSION,
                            end_to_end_id = Seq,
                            hop_by_hop_id = Seq},
-    diameter_codec:encode(Dict, #diameter_packet{header = Hdr,
-                                                 msg = Rec}).
+    diameter_codec:encode(Dict, Opts, #diameter_packet{header = Hdr,
+                                                       msg = Rec}).
 
 %% incoming/2
 
@@ -797,14 +805,15 @@ rcv('DPA' = N,
     = Pkt,
     #state{dictionary = Dict0,
            transport = TPid,
-           dpr = {X, Hid, Eid}}) ->
+           dpr = {X, Hid, Eid},
+           codec = Opts}) ->
     ?LOG(recv, N),
     X orelse begin
                  %% Only count DPA in response to a DPR sent by the
                  %% service: explicit DPR is counted in the same way
                  %% as other explicitly sent requests.
                  incr(recv, H, Dict0),
-                 incr_rc(recv, diameter_codec:decode(Dict0, Pkt), Dict0)
+                 incr_rc(recv, diameter_codec:decode(Dict0, Opts, Pkt), Dict0)
              end,
     diameter_peer:close(TPid),
     {stop, N};
@@ -865,7 +874,7 @@ outgoing(#diameter_packet{header = #diameter_header{application_id = 0,
             invalid(false, dpr_after_dpr, H)   %% DPR sent: discard
     end;
 
-%% Explict CER or DWR: discard. These are sent by us.
+%% Explicit CER or DWR: discard. These are sent by us.
 outgoing(#diameter_packet{header = #diameter_header{application_id = 0,
                                                     cmd_code = C,
                                                     is_request = true}
@@ -901,15 +910,21 @@ header(Bin) ->  %% DWR
 %% Incoming CER or DPR.
 
 handle_request(Name,
-               #diameter_packet{header = H} = Pkt,
-               #state{dictionary = Dict0} = S) ->
+               #diameter_packet{header = H}
+               = Pkt,
+               #state{dictionary = Dict0,
+                      codec = Opts}
+               = S) ->
     ?LOG(recv, Name),
     incr(recv, H, Dict0),
-    send_answer(Name, diameter_codec:decode(Dict0, Pkt), S).
+    send_answer(Name, diameter_codec:decode(Dict0, Opts, Pkt), S).
 
 %% send_answer/3
 
-send_answer(Type, ReqPkt, #state{transport = TPid, dictionary = Dict} = S) ->
+send_answer(Type, ReqPkt, #state{transport = TPid,
+                                 dictionary = Dict,
+                                 codec = Opts}
+                          = S) ->
     incr_error(recv, ReqPkt, Dict),
 
     #diameter_packet{header = H,
@@ -928,7 +943,7 @@ send_answer(Type, ReqPkt, #state{transport = TPid, dictionary = Dict} = S) ->
                            msg = Msg,
                            transport_data = TD},
 
-    AnsPkt = diameter_codec:encode(Dict, Pkt),
+    AnsPkt = diameter_codec:encode(Dict, Opts, Pkt),
 
     incr(send, AnsPkt, Dict),
     incr_rc(send, AnsPkt, Dict),
@@ -955,8 +970,6 @@ build_answer('CER',
              = Pkt,
              #state{dictionary = Dict0}
              = S) ->
-    diameter_codec:setopts([{string_decode, false}]),
-
     {SupportedApps, RCaps, CEA} = recv_CER(CER, S),
 
     [RC, IS] = Dict0:'#get-'(['Result-Code', 'Inband-Security-Id'], CEA),
@@ -1157,18 +1170,16 @@ recv_CER(CER, #state{service = Svc, dictionary = Dict}) ->
 handle_CEA(#diameter_packet{header = H}
            = Pkt,
            #state{dictionary = Dict0,
-                  service = #diameter_service{capabilities = LCaps}}
+                  service = #diameter_service{capabilities = LCaps},
+                  codec = Opts}
            = S) ->
     incr(recv, H, Dict0),
 
     #diameter_packet{}
         = DPkt
-        = diameter_codec:decode(Dict0, Pkt),
-
-    diameter_codec:setopts([{string_decode, false}]),
+        = diameter_codec:decode(Dict0, Opts, Pkt),
 
     RC = result_code(incr_rc(recv, DPkt, Dict0)),
-
     {SApps, IS, RCaps} = recv_CEA(DPkt, S),
 
     #diameter_caps{origin_host = {OH, DH}}
@@ -1356,8 +1367,9 @@ dpr([], [Reason | _], S) ->
 
 -record(opts, {cause, timeout}).
 
-send_dpr(Reason, Opts, #state{dictionary = Dict,
-                              service = #diameter_service{capabilities = Caps}}
+send_dpr(Reason, DprOpts, #state{dictionary = Dict,
+                                 service = #diameter_service{capabilities = Caps},
+                                 codec = Opts}
                        = S) ->
     #opts{cause = Cause, timeout = Tmo}
         = lists:foldl(fun opt/2,
@@ -1366,7 +1378,7 @@ send_dpr(Reason, Opts, #state{dictionary = Dict,
                                         _         -> ?REBOOT
                                     end,
                             timeout = dpa_timeout()},
-                      Opts),
+                      DprOpts),
     #diameter_caps{origin_host = {OH, _},
                    origin_realm = {OR, _}}
         = Caps,
@@ -1374,6 +1386,7 @@ send_dpr(Reason, Opts, #state{dictionary = Dict,
     Pkt = encode(['DPR', {'Origin-Host', OH},
                          {'Origin-Realm', OR},
                          {'Disconnect-Cause', Cause}],
+                 Opts,
                  Dict),
     send_dpr(false, Pkt, Tmo, S).
 
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index e4f77e3a24..8e383818ea 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -88,12 +88,6 @@
 %% outside of the service process.
 -define(STATE_TABLE, ?MODULE).
 
-%% The default sequence mask.
--define(NOMASK, {0,32}).
-
-%% The default restrict_connections.
--define(RESTRICT, nodes).
-
 %% Workaround for dialyzer's lack of understanding of match specs.
 -type match(T)
    :: T | '_' | '$1' | '$2'.
@@ -110,21 +104,17 @@
          service :: #diameter_service{},
          watchdogT = ets_new(watchdogs) %% #watchdog{} at start
                   :: ets:tid(),
-         peerT,         %% undefined in new code, but remain for upgrade
-         shared_peers,  %% reasons. Replaced by local/remote.
-         local_peers,   %%
          local  :: {ets:tid(), ets:tid(), ets:tid()},
          remote :: {ets:tid(), ets:tid(), ets:tid()},
          monitor = false :: false | pid(),   %% process to die with
-         options
-         :: [{sequence, diameter:sequence()}  %% sequence mask
-             | {share_peers, diameter:remotes()}       %% broadcast to
-             | {use_shared_peers, diameter:remotes()}  %% use from
-             | {restrict_connections, diameter:restriction()}
-             | {strict_mbit, boolean()}
-             | {string_decode, boolean()}
-             | {incoming_maxlen, diameter:message_length()}]}).
-%% shared_peers reflects the peers broadcast from remote nodes.
+         options :: #{sequence := diameter:sequence(),  %% sequence mask
+                      share_peers := diameter:remotes(),%% broadcast to
+                      use_shared_peers := diameter:remotes(),%% use from
+                      restrict_connections := diameter:restriction(),
+                      incoming_maxlen := diameter:message_length(),
+                      strict_mbit := boolean(),
+                      string_decode := boolean(),
+                      spawn_opt := list() | {module(), atom(), list()}}}).
 
 %% Record representing an RFC 3539 watchdog process implemented by
 %% diameter_watchdog.
@@ -284,7 +274,7 @@ whois(SvcName) ->
 %% ---------------------------------------------------------------------------
 
 -spec pick_peer(SvcName, AppOrAlias, Opts)
-   -> {{TPid, Caps, App}, Mask, SvcOpts}
+   -> {{{TPid, Caps}, App}, SvcOpts}
     | false  %% no selection
     | {error, no_service}
  when SvcName :: diameter:service_name(),
@@ -296,10 +286,7 @@ whois(SvcName) ->
       TPid :: pid(),
       Caps :: #diameter_caps{},
       App  :: #diameter_app{},
-      Mask :: diameter:sequence(),
-      SvcOpts :: [diameter:service_opt()].
-%% Extract Mask in the returned tuple so that diameter_traffic doesn't
-%% need to know about the ordering of SvcOpts used here.
+      SvcOpts :: map().
 
 pick_peer(SvcName, App, Opts) ->
     pick(lookup_state(SvcName), App, Opts).
@@ -319,7 +306,7 @@ pick(#state{service = #diameter_service{applications = Apps}}
 pick(_, false = No, _) ->
     No;
 
-pick(#state{options = [{_, Mask} | SvcOpts]}
+pick(#state{options = SvcOpts}
      = S,
      #diameter_app{module = ModX, dictionary = Dict}
      = App0,
@@ -327,8 +314,8 @@ pick(#state{options = [{_, Mask} | SvcOpts]}
     App = App0#diameter_app{module = ModX ++ Xtra},
     [_,_] = RealmAndHost = diameter_lib:eval([DestF, Dict]),
     case pick_peer(App, RealmAndHost, Filter, S) of
-        {TPid, Caps} ->
-            {{TPid, Caps, App}, Mask, SvcOpts};
+        {_TPid, _Caps} = TC ->
+            {{TC, App}, SvcOpts};
         false = No ->
             No
     end.
@@ -556,81 +543,9 @@ terminate(Reason, #state{service_name = Name, local = {PeerT, _, _}} = S) ->
 %% # code_change/3
 %% ---------------------------------------------------------------------------
 
-code_change(_FromVsn, #state{} = S, _Extra) ->
-    {ok, S};
-
-%% Don't support downgrade since we won't in appup.
-code_change({down = T, _}, _, _Extra) ->
-    {error, T};
-
-%% Upgrade local/shared peers dicts populated in old code. Don't
-code_change(_FromVsn, S0, _Extra) ->
-    {state, Id, SvcName, Svc, WT, PeerT, SDict, LDict, Monitor, Opts}
-        = S0,
-
-    init_peers(LT = setelement(1, {PT, _, _} = init_peers(), PeerT),
-               fun({_,A}) -> A end),
-    init_peers(init_peers(RT = init_peers(), SDict),
-               fun(A) -> A end),
-
-    S = #state{id = Id,
-               service_name = SvcName,
-               service = Svc,
-               watchdogT = WT,
-               peerT = PT,  %% empty
-               shared_peers = SDict,
-               local_peers = LDict,
-               local = LT,
-               remote = RT,
-               monitor = Monitor,
-               options = Opts},
-
-    %% Replacing the table entry and deleting the old shared tables
-    %% can make outgoing requests return {error, no_connection} until
-    %% everyone is running new code. Don't delete the tables to avoid
-    %% crashing request processes.
-    ets:delete_all_objects(SDict),
-    ets:delete_all_objects(LDict),
-    ets:insert(?STATE_TABLE, S),
+code_change(_FromVsn, S, _Extra) ->
     {ok, S}.
 
-%% init_peers/2
-
-%% Populate app and identity bags from a new-style #peer{} sets.
-init_peers({PeerT, _, _} = T, F)
-  when is_function(F) ->
-    ets:foldl(fun(#peer{pid = P, apps = As, caps = C}, N) ->
-                      insert_peer(P, lists:map(F, As), C, T),
-                      N+1
-              end,
-              0,
-              PeerT);
-
-%% Populate #peer{} table given a shared peers dict.
-init_peers({PeerT, _, _}, SDict) ->
-    dict:fold(fun(P, As, N) ->
-                      ets:update_element(PeerT, P, {#peer.apps, As}),
-                      N+1
-              end,
-              0,
-              diameter_dict:fold(fun(A, Ps, D) ->
-                                         init_peers(A, Ps, PeerT, D)
-                                 end,
-                                 dict:new(),
-                                 SDict)).
-
-%% init_peers/4
-
-init_peers(App, TCs, PeerT, Dict) ->
-    lists:foldl(fun({P,C}, D) ->
-                        ets:insert(PeerT, #peer{pid = P,
-                                                apps = [],
-                                                caps = C}),
-                        dict:append(P, App, D)
-                end,
-                Dict,
-                TCs).
-
 %% ===========================================================================
 %% ===========================================================================
 
@@ -768,7 +683,7 @@ cfg_acc({SvcName, #diameter_service{applications = Apps} = Rec, Opts},
                local   = init_peers(),
                remote  = init_peers(),
                monitor = mref(get_value(monitor, Opts)),
-               options = service_options(Opts)},
+               options = service_options(lists:keydelete(monitor, 1, Opts))},
     {S, Acc};
 
 cfg_acc({_Ref, Type, _Opts} = T, {S, Acc})
@@ -784,24 +699,14 @@ init_peers() ->
                                %%  TPid}
 
 service_options(Opts) ->
-    [{sequence, proplists:get_value(sequence, Opts, ?NOMASK)},
-     {share_peers, get_value(share_peers, Opts)},
-     {use_shared_peers, get_value(use_shared_peers, Opts)},
-     {restrict_connections, proplists:get_value(restrict_connections,
-                                                Opts,
-                                                ?RESTRICT)},
-     {spawn_opt, proplists:get_value(spawn_opt, Opts, [])},
-     {string_decode, proplists:get_value(string_decode, Opts, true)},
-     {incoming_maxlen, proplists:get_value(incoming_maxlen, Opts, 16#FFFFFF)},
-     {strict_mbit, proplists:get_value(strict_mbit, Opts, true)}].
-%% The order of options is significant since we match against the list.
+    maps:from_list(Opts).
 
 mref(false = No) ->
     No;
 mref(P) ->
     monitor(process, P).
 
-init_shared(#state{options = [_, _, {_,T} | _],
+init_shared(#state{options = #{use_shared_peers := T},
                    service_name = Svc}) ->
     notify(T, Svc, {service, self()}).
 
@@ -899,7 +804,8 @@ start(Ref, Type, Opts, State) ->
 
 start(Ref, Type, Opts, N, #state{watchdogT = WatchdogT,
                                  local = {PeerT, _, _},
-                                 options = SvcOpts,
+                                 options = #{string_decode := SD}
+                                 = SvcOpts0,
                                  service_name = SvcName,
                                  service = Svc0})
   when Type == connect;
@@ -907,21 +813,25 @@ start(Ref, Type, Opts, N, #state{watchdogT = WatchdogT,
     #diameter_service{applications = Apps}
         = Svc1
         = merge_service(Opts, Svc0),
-    Svc = binary_caps(Svc1, proplists:get_value(string_decode, SvcOpts, true)),
-    RecvData = diameter_traffic:make_recvdata([SvcName,
-                                               PeerT,
-                                               Apps,
-                                               SvcOpts]),
-    T = {{spawn_opts([Opts, SvcOpts]), RecvData}, Opts, SvcOpts, Svc},
+    Svc = binary_caps(Svc1, SD),
+    SvcOpts = merge_options(Opts, SvcOpts0),
+    RecvData = diameter_traffic:make_recvdata([SvcName, PeerT, Apps, SvcOpts]),
+    T = {Opts, SvcOpts, RecvData, Svc},
     Rec = #watchdog{type = Type,
                     ref = Ref,
                     options = Opts},
+
     diameter_lib:fold_n(fun(_,A) ->
                                 [wd(Type, Ref, T, WatchdogT, Rec) | A]
                         end,
                         [],
                         N).
 
+merge_options(Opts, SvcOpts) ->
+    Keys = maps:keys(SvcOpts),
+    Map = maps:from_list([KV || {K,_} = KV <- Opts, lists:member(K, Keys)]),
+    maps:merge(SvcOpts, Map).
+
 binary_caps(Svc, true) ->
     Svc;
 binary_caps(#diameter_service{capabilities = Caps} = Svc, false) ->
@@ -936,12 +846,6 @@ wd(Type, Ref, T, WatchdogT, Rec) ->
 %% record so that each watchdog may get a different record. This
 %% record is what is passed back into application callbacks.
 
-spawn_opts(Optss) ->
-    SpawnOpts = get_value(spawn_opt, Optss, []),
-    [T || T <- SpawnOpts,
-          T /= link,
-          T /= monitor].
-
 start_watchdog(Type, Ref, T) ->
     {_MRef, Pid} = diameter_watchdog:start({Type, Ref}, T),
     Pid.
@@ -1154,18 +1058,6 @@ keyfind([Key | Rest], Pos, L) ->
             T
     end.
 
-%% get_value/3
-
-get_value(_, [], Def) ->
-    Def;
-get_value(Key, [L | Rest], Def) ->
-    case lists:keyfind(Key, 1, L) of
-        {_,V} ->
-            V;
-        _ ->
-            get_value(Key, Rest, Def)
-    end.
-
 %% find_outgoing_app/2
 
 find_outgoing_app(Alias, Apps) ->
@@ -1463,19 +1355,19 @@ send_event(#diameter_event{service = SvcName} = E) ->
 %% # share_peer/5
 %% ---------------------------------------------------------------------------
 
-share_peer(up, Caps, Apps, TPid, #state{options = [_, {_,T} | _],
+share_peer(up, Caps, Apps, TPid, #state{options = #{share_peers := SP},
                                         service_name = Svc}) ->
-    notify(T, Svc, {peer, TPid, [A || {_,A} <- Apps], Caps});
+    notify(SP, Svc, {peer, TPid, [A || {_,A} <- Apps], Caps});
 
-share_peer(down, _Caps, _Apps, TPid, #state{options = [_, {_,T} | _],
+share_peer(down, _Caps, _Apps, TPid, #state{options = #{share_peers := SP},
                                             service_name = Svc}) ->
-    notify(T, Svc, {peer, TPid}).
+    notify(SP, Svc, {peer, TPid}).
 
 %% ---------------------------------------------------------------------------
 %% # share_peers/2
 %% ---------------------------------------------------------------------------
 
-share_peers(Pid, #state{options = [_, {_,SP} | _],
+share_peers(Pid, #state{options = #{share_peers := SP},
                         local = {PeerT, AppT, _}}) ->
     is_remote(Pid, SP)
         andalso ets:foldl(fun(T, N) -> N + sp(Pid, AppT, T) end,
@@ -1507,7 +1399,8 @@ is_remote(Pid, T) ->
 %% # remote_peer_up/4
 %% ---------------------------------------------------------------------------
 
-remote_peer_up(TPid, Aliases, Caps, #state{options = [_, _, {_,T} | _]} = S) ->
+remote_peer_up(TPid, Aliases, Caps, #state{options = #{use_shared_peers := T}}
+                                    = S) ->
     is_remote(TPid, T) andalso rpu(TPid, Aliases, Caps, S).
 
 rpu(TPid, Aliases, Caps, #state{service = Svc, remote = RT}) ->
diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl
index ccfab22e9c..af7ac10f13 100644
--- a/lib/diameter/src/base/diameter_traffic.erl
+++ b/lib/diameter/src/base/diameter_traffic.erl
@@ -54,6 +54,8 @@
 -define(RELAY, ?DIAMETER_DICT_RELAY).
 -define(BASE,  ?DIAMETER_DICT_COMMON).  %% Note: the RFC 3588 dictionary
 
+-define(DEFAULT(V, Def), if V == undefined -> Def; true -> V end).
+
 %% Table containing outgoing entries that live and die with
 %% peer_up/down. The name is historic, since the table used to contain
 %% information about outgoing requests for which an answer has yet to
@@ -73,9 +75,9 @@
          service_name :: diameter:service_name(),
          apps         :: [#diameter_app{}],
          sequence     :: diameter:sequence(),
-         codec        :: [{string_decode, boolean()}
-                          | {strict_mbit, boolean()}
-                          | {incoming_maxlen, diameter:message_length()}]}).
+         codec        :: #{string_decode := boolean(),
+                           strict_mbit := boolean(),
+                           incoming_maxlen := diameter:message_length()}}).
 %% Note that incoming_maxlen is currently handled in diameter_peer_fsm,
 %% so that any message exceeding the maximum is discarded. Retain the
 %% option in case we want to extend the values and semantics.
@@ -85,8 +87,7 @@
         {ref        :: reference(),         %% used to receive answer
          caller     :: pid() | undefined,   %% calling process
          handler    :: pid(),               %% request process
-         transport  :: pid() | undefined,   %% peer process
-         caps       :: #diameter_caps{} | undefined,     %% of connection
+         peer       :: undefined | {pid(), #diameter_caps{}},
          packet     :: #diameter_packet{} | undefined}). %% of request
 
 %% ---------------------------------------------------------------------------
@@ -94,15 +95,17 @@
 %% ---------------------------------------------------------------------------
 
 make_recvdata([SvcName, PeerT, Apps, SvcOpts | _]) ->
-    {_,_} = Mask = proplists:get_value(sequence, SvcOpts),
-    #recvdata{service_name = SvcName,
-              peerT = PeerT,
-              apps = Apps,
-              sequence = Mask,
-              codec = [T || {K,_} = T <- SvcOpts,
-                            lists:member(K, [string_decode,
-                                             incoming_maxlen,
-                                             strict_mbit])]}.
+    #{sequence := {_,_} = Mask, spawn_opt := Opts}
+        = SvcOpts,
+    {Opts, #recvdata{service_name = SvcName,
+                     peerT = PeerT,
+                     apps = Apps,
+                     sequence = Mask,
+                     codec = maps:with([string_decode,
+                                        strict_mbit,
+                                        ordered_encode,
+                                        incoming_maxlen],
+                                       SvcOpts)}}.
 
 %% ---------------------------------------------------------------------------
 %% peer_up/1
@@ -209,8 +212,9 @@ incr_rc(Dir, Pkt, TPid, Dict0) ->
 %% ---------------------------------------------------------------------------
 
 -spec receive_message(pid(), Route, #diameter_packet{}, module(), RecvData)
-   -> pid()
-    | boolean()
+   -> pid()     %% request handler
+    | boolean() %% answer, known request or not
+    | discard   %% request discarded by MFA
  when Route :: {Handler, RequestRef, Seqs}
              | Ack,
       RecvData :: {[SpawnOpt], #recvdata{}},
@@ -229,7 +233,8 @@ receive_message(TPid, Route, Pkt, Dict0, RecvData) ->
 %% Incoming request ...
 recv(true, Ack, TPid, Pkt, Dict0, T)
   when is_boolean(Ack) ->
-    spawn_request(Ack, TPid, Pkt, Dict0, T);
+    {Opts, RecvData} = T,
+    spawn_request(Ack, TPid, Pkt, Dict0, RecvData, Opts);
 
 %% ... answer to known request ...
 recv(false, {Pid, Ref, TPid}, _, Pkt, Dict0, _) ->
@@ -251,67 +256,89 @@ recv(false, false, TPid, Pkt, _, _) ->
     incr(TPid, {{unknown, 0}, recv, discarded}),
     false.
 
-%% spawn_request/5
+%% spawn_request/6
+
+%% An MFA should return a pid() or the atom 'discard'. The latter
+%% results in an acknowledgment back to the transport process when
+%% appropriate, to ensure that send/recv callbacks can count
+%% outstanding requests. Acknowledgement is implicit if the
+%% handler process dies (in a handle_request callback for example).
+spawn_request(Ack, TPid, Pkt, Dict0, RecvData, {M,F,A}) ->
+    ReqF = fun() ->
+                   ack(Ack, TPid, recv_request(Ack, TPid, Pkt, Dict0, RecvData))
+           end,
+    ack(Ack, TPid, apply(M, F, [ReqF | A]));
 
-spawn_request(Ack, TPid, Pkt, Dict0, {Opts, RecvData}) ->
+%% A spawned process acks implicitly when it dies, so there's no need
+%% to handle 'discard'.
+spawn_request(Ack, TPid, Pkt, Dict0, RecvData, Opts) ->
     spawn_opt(fun() ->
                       recv_request(Ack, TPid, Pkt, Dict0, RecvData)
               end,
               Opts).
 
+%% ack/3
+
+ack(Ack, TPid, RC) ->
+    RC == discard andalso Ack andalso (TPid ! {send, false}),
+    RC.
+
 %% ---------------------------------------------------------------------------
 %% recv_request/5
 %% ---------------------------------------------------------------------------
 
+-spec recv_request(Ack :: boolean(),
+                   TPid :: pid(),
+                   #diameter_packet{},
+                   Dict0 :: module(),
+                   #recvdata{})
+   -> ok        %% answer was sent
+    | discard   %% or not
+    | false.    %% no transport
+
 recv_request(Ack,
              TPid,
              #diameter_packet{header = #diameter_header{application_id = Id}}
              = Pkt,
              Dict0,
              #recvdata{peerT = PeerT,
-                       apps = Apps,
-                       codec = Opts}
+                       apps = Apps}
              = RecvData) ->
     Ack andalso (TPid ! {handler, self()}),
-    diameter_codec:setopts([{common_dictionary, Dict0} | Opts]),
-    send_A(recv_R(diameter_service:find_incoming_app(PeerT, TPid, Id, Apps),
-                  TPid,
-                  Pkt,
-                  Dict0,
-                  RecvData),
-           TPid,
-           Dict0,
-           RecvData).
-
-%% recv_R/5
-
-recv_R({#diameter_app{id = Id, dictionary = AppDict} = App, Caps},
-       TPid,
-       Pkt0,
-       Dict0,
-       RecvData) ->
-    incr(recv, Pkt0, TPid, AppDict),
-    Pkt = errors(Id, diameter_codec:decode(Id, AppDict, Pkt0)),
-    incr_error(recv, Pkt, TPid, AppDict),
-    {Caps, Pkt, App, recv_R(App, TPid, Dict0, Caps, RecvData, Pkt)};
-%% Note that the decode is different depending on whether or not Id is
-%% ?APP_ID_RELAY.
-
-%%   DIAMETER_APPLICATION_UNSUPPORTED   3007
-%%      A request was sent for an application that is not supported.
-
-recv_R(#diameter_caps{}
-       = Caps,
-       _TPid,
-       #diameter_packet{errors = Es}
-       = Pkt,
-       _Dict0,
-       _RecvData) ->
-    {Caps, Pkt#diameter_packet{avps = collect_avps(Pkt),
-                               errors = [3007 | Es]}};
+    case diameter_service:find_incoming_app(PeerT, TPid, Id, Apps) of
+        {#diameter_app{id = Aid, dictionary = AppDict} = App, Caps} ->
+            incr(recv, Pkt, TPid, AppDict),
+            DecPkt = decode(Aid, AppDict, RecvData, Pkt),
+            incr_error(recv, DecPkt, TPid, AppDict),
+            send_A(recv_R(App, TPid, Dict0, Caps, RecvData, DecPkt),
+                   TPid,
+                   App,
+                   Dict0,
+                   RecvData,
+                   DecPkt,
+                   Caps);
+        #diameter_caps{} = Caps ->
+            %%   DIAMETER_APPLICATION_UNSUPPORTED   3007
+            %%      A request was sent for an application that is not
+            %%      supported.
+            RC = 3007,
+            Es = Pkt#diameter_packet.errors,
+            DecPkt = Pkt#diameter_packet{avps = collect_avps(Pkt),
+                                         errors = [RC | Es]},
+            send_answer(answer_message(RC, Dict0, Caps, DecPkt),
+                        TPid,
+                        Dict0,
+                        Dict0,
+                        Dict0,
+                        RecvData,
+                        DecPkt,
+                        [[]]);
+        false = No ->  %% transport has gone down
+            No
+    end.
 
-recv_R(false = No, _, _, _, _) ->  %% transport has gone down
-    No.
+decode(Id, Dict, #recvdata{codec = Opts}, Pkt) ->
+    errors(Id, diameter_codec:decode(Id, Dict, Opts, Pkt)).
 
 collect_avps(Pkt) ->
     case diameter_codec:collect_avps(Pkt) of
@@ -321,6 +348,14 @@ collect_avps(Pkt) ->
             Avps
     end.
 
+%% send_A/7
+
+send_A([T | Fs], TPid, App, Dict0, RecvData, DecPkt, Caps) ->
+    send_A(T, TPid, App, Dict0, RecvData, DecPkt, Caps, Fs);
+
+send_A(discard = No, _, _, _, _, _, _) ->
+    No.
+
 %% recv_R/6
 
 %% Answer errors ourselves ...
@@ -330,9 +365,9 @@ recv_R(#diameter_app{options = [_, {request_errors, E} | _]},
        _Caps,
        _RecvData,
        #diameter_packet{errors = [RC|_]})  %% a detected 3xxx is hd
-  when E == answer, (Dict0 /= ?BASE orelse 3 == RC div 1000);
+  when E == answer, Dict0 /= ?BASE orelse 3 == RC div 1000;
        E == answer_3xxx, 3 == RC div 1000 ->
-    {{answer_message, rc(RC)}, [], []};
+    [{answer_message, rc(RC)}, []];
 
 %% ... or make a handle_request callback. Note that
 %% Pkt#diameter_packet.msg = undefined in the 3001 case.
@@ -424,24 +459,24 @@ errors(_, Pkt) ->
 %% command code in this case. It will also then ignore Dict and use
 %% the base encoder.
 request_cb({reply, _Ans} = T, _App, EvalPktFs, EvalFs) ->
-    {T, EvalPktFs, EvalFs};
+    [T, EvalPktFs | EvalFs];
 
 %% An 3xxx result code, for which the E-bit is set in the header.
 request_cb({protocol_error, RC}, _App, EvalPktFs, EvalFs)
   when 3 == RC div 1000 ->
-    {{answer_message, RC}, EvalPktFs, EvalFs};
+    [{answer_message, RC}, EvalPktFs | EvalFs];
 
 request_cb({answer_message, RC} = T, _App, EvalPktFs, EvalFs)
   when 3 == RC div 1000;
        5 == RC div 1000 ->
-    {T, EvalPktFs, EvalFs};
+    [T, EvalPktFs | EvalFs];
 
 %% RFC 3588 says we must reply 3001 to anything unrecognized or
 %% unsupported. 'noreply' is undocumented (and inappropriately named)
 %% backwards compatibility for this, protocol_error the documented
 %% alternative.
 request_cb(noreply, _App, EvalPktFs, EvalFs) ->
-    {{answer_message, 3001}, EvalPktFs, EvalFs};
+    [{answer_message, 3001}, EvalPktFs | EvalFs];
 
 %% Relay a request to another peer. This is equivalent to doing an
 %% explicit call/4 with the message in question except that (1) a loop
@@ -462,7 +497,7 @@ request_cb({A, Opts}, #diameter_app{id = Id}, EvalPktFs, EvalFs)
   when A == relay, Id == ?APP_ID_RELAY;
        A == proxy, Id /= ?APP_ID_RELAY;
        A == resend ->
-    {{call, Opts}, EvalPktFs, EvalFs};
+    [{call, Opts}, EvalPktFs | EvalFs];
 
 request_cb(discard = No, _, _, _) ->
     No;
@@ -476,71 +511,95 @@ request_cb({eval, RC, F}, App, EvalPktFs, Fs) ->
 request_cb(T, App, _, _) ->
     ?ERROR({invalid_return, T, handle_request, App}).
 
-%% send_A/4
+%% send_A/8
+
+send_A({reply, Ans}, TPid, App, Dict0, RecvData, Pkt, _Caps, Fs) ->
+    AppDict = App#diameter_app.dictionary,
+    MsgDict = msg_dict(AppDict, Dict0, Ans),
+    send_answer(Ans,
+                TPid,
+                MsgDict,
+                AppDict,
+                Dict0,
+                RecvData,
+                Pkt,
+                Fs);
+
+send_A({call, Opts}, TPid, App, Dict0, RecvData, Pkt, Caps, Fs) ->
+    AppDict = App#diameter_app.dictionary,
+    case resend(Opts, Caps, Pkt, App, Dict0, RecvData) of
+        #diameter_packet{bin = Bin} = Ans -> %% answer: reset hop by hop id
+            #diameter_packet{header = #diameter_header{hop_by_hop_id = Id},
+                             transport_data = TD}
+                = Pkt,
+            Reset = diameter_codec:hop_by_hop_id(Id, Bin),
+            MsgDict = msg_dict(AppDict, Dict0, Ans),
+            send_answer(Ans#diameter_packet{bin = Reset,
+                                            transport_data = TD},
+                        TPid,
+                        MsgDict,
+                        AppDict,
+                        Dict0,
+                        Fs);
+        RC ->
+            send_answer(answer_message(RC, Dict0, Caps, Pkt),
+                        TPid,
+                        Dict0,
+                        AppDict,
+                        Dict0,
+                        RecvData,
+                        Pkt,
+                        Fs)
+    end;
+
+%% RFC 3588 only allows 3xxx errors in an answer-message. RFC 6733
+%% added the possibility of setting 5xxx.
 
-send_A({Caps, Pkt}, TPid, Dict0, _RecvData) ->  %% unsupported application
-    #diameter_packet{errors = [RC|_]} = Pkt,
-    send_A(answer_message(RC, Caps, Dict0, Pkt),
-           TPid,
-           {Dict0, Dict0},
-           Pkt,
-           [],
-           []);
+send_A({answer_message, RC} = T, TPid, App, Dict0, RecvData, Pkt, Caps, Fs) ->
+    Dict0 /= ?BASE orelse 3 == RC div 1000
+        orelse ?ERROR({invalid_return, T, handle_request, App}),
+    send_answer(answer_message(RC, Dict0, Caps, Pkt),
+                TPid,
+                Dict0,
+                App#diameter_app.dictionary,
+                Dict0,
+                RecvData,
+                Pkt,
+                Fs).
 
-send_A({Caps, Pkt, App, {T, EvalPktFs, EvalFs}}, TPid, Dict0, RecvData) ->
-    send_A(answer(T, Caps, Pkt, App, Dict0, RecvData),
-           TPid,
-           {App#diameter_app.dictionary, Dict0},
-           Pkt,
-           EvalPktFs,
-           EvalFs);
+%% send_answer/8
 
-send_A(_, _, _, _) ->
-    ok.
+%% Skip the setting of Result-Code and Failed-AVP's below. This is
+%% undocumented and shouldn't be relied on.
+send_answer([Ans], TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs)
+  when [] == Pkt#diameter_packet.errors ->
+    send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs);
+send_answer([Ans], TPid, MsgDict, AppDict, Dict0, RecvData, Pkt0, Fs) ->
+    Pkt = Pkt0#diameter_packet{errors = []},
+    send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, Pkt, Fs);
+
+send_answer(Ans, TPid, MsgDict, AppDict, Dict0, RecvData, DecPkt, Fs) ->
+    Pkt = encode({MsgDict, AppDict},
+                 TPid,
+                 RecvData#recvdata.codec,
+                 make_answer_packet(Ans, DecPkt, MsgDict, Dict0)),
+    send_answer(Pkt, TPid, MsgDict, AppDict, Dict0, Fs).
 
-%% send_A/6
+%% send_answer/6
 
-send_A(T, TPid, {AppDict, Dict0} = DictT0, ReqPkt, EvalPktFs, EvalFs) ->
-    {MsgDict, Pkt} = reply(T, TPid, DictT0, EvalPktFs, ReqPkt),
+send_answer(Pkt, TPid, MsgDict, AppDict, Dict0, [EvalPktFs | EvalFs]) ->
+    eval_packet(Pkt, EvalPktFs),
     incr(send, Pkt, TPid, AppDict),
     incr_rc(send, Pkt, TPid, {MsgDict, AppDict, Dict0}),  %% count outgoing
-    send(TPid, Pkt, _Route = self()),
+    send(TPid, z(Pkt), _Route = self()),
     lists:foreach(fun diameter_lib:eval/1, EvalFs).
 
-%% answer/6
-
-answer({reply, Ans}, _Caps, _Pkt, App, Dict0, _RecvData) ->
-    {msg_dict(App#diameter_app.dictionary, Dict0, Ans), Ans};
-
-answer({call, Opts}, Caps, Pkt, App, Dict0, RecvData) ->
-    #diameter_caps{origin_host = {OH,_}}
-        = Caps,
-    #diameter_packet{avps = Avps}
-        = Pkt,
-    {Code, _Flags, Vid} = Dict0:avp_header('Route-Record'),
-    resend(is_loop(Code, Vid, OH, Dict0, Avps),
-           Opts,
-           Caps,
-           Pkt,
-           App,
-           Dict0,
-           RecvData);
-
-%% RFC 3588 only allows 3xxx errors in an answer-message. RFC 6733
-%% added the possibility of setting 5xxx.
-answer({answer_message, RC} = T, Caps, Pkt, App, Dict0, _RecvData)  ->
-    Dict0 /= ?BASE orelse 3 == RC div 1000
-        orelse ?ERROR({invalid_return, T, handle_request, App}),
-    answer_message(RC, Caps, Dict0, Pkt).
-
 %% msg_dict/3
 %%
 %% Return the dictionary defining the message grammar in question: the
 %% application dictionary or the common dictionary.
 
-msg_dict(AppDict, Dict0, [Msg])
-  when is_list(Msg);
-       is_tuple(Msg) ->
+msg_dict(AppDict, Dict0, [Msg]) ->
     msg_dict(AppDict, Dict0, Msg);
 
 msg_dict(AppDict, Dict0, Msg) ->
@@ -571,14 +630,10 @@ is_answer_message(Rec, Dict) ->
         error:_ -> false
     end.
 
-%% answer_message/4
+%% resend/6
 
-answer_message(RC,
-               #diameter_caps{origin_host  = {OH,_},
-                              origin_realm = {OR,_}},
-               Dict0,
-               Pkt) ->
-    {Dict0, answer_message(OH, OR, RC, Dict0, Pkt)}.
+resend(Opts, Caps, Pkt, App, Dict0, RecvData) ->
+    resend(is_loop(Dict0, Caps, Pkt), Opts, Caps, Pkt, App, Dict0, RecvData).
 
 %% resend/7
 
@@ -588,8 +643,8 @@ answer_message(RC,
 %%      if one is available, but the peer reporting the error has
 %%      identified a configuration problem.
 
-resend(true, _Opts, Caps, Pkt, _App, Dict0, _RecvData) ->
-    answer_message(3005, Caps, Dict0, Pkt);
+resend(true, _Opts, _Caps, _Pkt, _App, _Dict0, _RecvData) ->
+    3005;
 
 %% 6.1.8.  Relaying and Proxying Requests
 %%
@@ -599,11 +654,9 @@ resend(true, _Opts, Caps, Pkt, _App, Dict0, _RecvData) ->
 
 resend(false,
        Opts,
-       #diameter_caps{origin_host = {_,OH}}
-       = Caps,
+       #diameter_caps{origin_host = {_,OH}},
        #diameter_packet{header = Hdr0,
-                        avps = Avps}
-       = Pkt,
+                        avps = Avps},
        App,
        Dict0,
        #recvdata{service_name = SvcName,
@@ -612,7 +665,12 @@ resend(false,
     Seq = diameter_session:sequence(Mask),
     Hdr = Hdr0#diameter_header{hop_by_hop_id = Seq},
     Msg = [Hdr, Route | Avps],  %% reordered at encode
-    resend(send_request(SvcName, App, Msg, Opts), Caps, Dict0, Pkt).
+    case send_request(SvcName, App, Msg, Opts) of
+        #diameter_packet{} = Ans ->
+            Ans;
+        _ ->
+            3002  %% DIAMETER_UNABLE_TO_DELIVER.
+    end.
 %% The incoming request is relayed with the addition of a
 %% Route-Record. Note the requirement on the return from call/4 below,
 %% which places a requirement on the value returned by the
@@ -629,96 +687,38 @@ resend(false,
 %% RFC 6.3 says that a relay agent does not modify Origin-Host but
 %% says nothing about a proxy. Assume it should behave the same way.
 
-%% resend/4
-%%
-%% Relay a reply to a relayed request.
-
-%% Answer from the peer: reset the hop by hop identifier.
-resend(#diameter_packet{bin = B}
-       = Pkt,
-       _Caps,
-       _Dict0,
-       #diameter_packet{header = #diameter_header{hop_by_hop_id = Id},
-                        transport_data = TD}) ->
-    Pkt#diameter_packet{bin = diameter_codec:hop_by_hop_id(Id, B),
-                        transport_data = TD};
-%% TODO: counters
+%% is_loop/3
 
-%% Or not: DIAMETER_UNABLE_TO_DELIVER.
-resend(_, Caps, Dict0, Pkt) ->
-    answer_message(3002, Caps, Dict0, Pkt).
+is_loop(Dict0,
+        #diameter_caps{origin_host = {OH,_}},
+        #diameter_packet{avps = Avps}) ->
+    {Code, _Flags, Vid} = Dict0:avp_header('Route-Record'),
+    is_loop(Code, Vid, OH, Avps).
 
-%% is_loop/5
+%% is_loop/4
 %%
 %% Is there a Route-Record AVP with our Origin-Host?
 
-is_loop(Code,
-        Vid,
-        Bin,
-        _Dict0,
-        [#diameter_avp{code = Code, vendor_id = Vid, data = Bin} | _]) ->
+is_loop(Code, Vid, Bin, [#diameter_avp{code = Code,
+                                       vendor_id = Vid,
+                                       data = Bin}
+                         | _]) ->
     true;
 
-is_loop(_, _, _, _, []) ->
+is_loop(_, _, _, []) ->
     false;
 
-is_loop(Code, Vid, OH, Dict0, [_ | Avps])
+is_loop(Code, Vid, OH, [_ | Avps])
   when is_binary(OH) ->
-    is_loop(Code, Vid, OH, Dict0, Avps);
-
-is_loop(Code, Vid, OH, Dict0, Avps) ->
-    is_loop(Code, Vid, Dict0:avp(encode, OH, 'Route-Record'), Dict0, Avps).
-
-%% reply/5
+    is_loop(Code, Vid, OH, Avps);
 
-%% Local answer ...
-reply({MsgDict, Ans}, TPid, {AppDict, Dict0}, Fs, ReqPkt) ->
-    local(Ans, TPid, {MsgDict, AppDict, Dict0}, Fs, ReqPkt);
-
-%% ... or relayed.
-reply(#diameter_packet{} = Pkt, _TPid, {AppDict, Dict0}, Fs, _ReqPkt) ->
-    eval_packet(Pkt, Fs),
-    {msg_dict(AppDict, Dict0, Pkt), Pkt}.
-
-%% local/5
-%%
-%% Send a locally originating reply.
-
-%% Skip the setting of Result-Code and Failed-AVP's below. This is
-%% undocumented and shouldn't be relied on.
-local([Msg], TPid, DictT, Fs, ReqPkt)
-  when is_list(Msg);
-       is_tuple(Msg) ->
-    local(Msg, TPid, DictT, Fs, ReqPkt#diameter_packet{errors = []});
-
-local(Msg, TPid, {MsgDict, AppDict, Dict0}, Fs, ReqPkt) ->
-    Pkt = encode({MsgDict, AppDict},
-                 TPid,
-                 reset(make_answer_packet(Msg, ReqPkt), MsgDict, Dict0),
-                 Fs),
-    {MsgDict, Pkt}.
-
-%% reset/3
-
-%% Header/avps list: send as is.
-reset(#diameter_packet{msg = [#diameter_header{} | _]} = Pkt, _, _) ->
-    Pkt;
-
-%% No errors to set or errors explicitly ignored.
-reset(#diameter_packet{errors = Es} = Pkt, _, _)
-  when Es == [];
-       Es == false ->
-    Pkt;
-
-%% Otherwise possibly set Result-Code and/or Failed-AVP.
-reset(#diameter_packet{msg = Msg, errors = Es} = Pkt, Dict, Dict0) ->
-    {RC, Failed} = select_error(Msg, Es, Dict0),
-    Pkt#diameter_packet{msg = reset(Msg, Dict, RC, Failed)}.
+is_loop(Code, Vid, OH, Avps) ->
+    is_loop(Code, Vid, list_to_binary(OH), Avps).
 
 %% select_error/3
 %%
 %% Extract the first appropriate RC or {RC, #diameter_avp{}}
-%% pair from an errors list, and accumulate all #diameter_avp{}.
+%% pair from an errors list, along with any leading #diameter_avp{}.
 %%
 %% RFC 6733:
 %%
@@ -733,95 +733,138 @@ reset(#diameter_packet{msg = Msg, errors = Es} = Pkt, Dict, Dict0) ->
 %%   indicated by the Result-Code AVP.  For practical purposes, this
 %%   Failed-AVP would typically refer to the first AVP processing error
 %%   that a Diameter node encounters.
+%%
+%% 3xxx can only be set in an answer setting the E-bit. RFC 6733 also
+%% allows 5xxx, RFC 3588 doesn't.
 
-select_error(Msg, Es, Dict0) ->
-    {RC, Avps} = lists:foldl(fun(T,A) -> select(T, A, Dict0) end,
-                             {is_answer_message(Msg, Dict0), []},
-                             Es),
-    {RC, lists:reverse(Avps)}.
+select_error(E, Es, Dict0) ->
+    select(E, Es, Dict0, []).
 
-%% Only integer() and {integer(), #diameter_avp{}} are the result of
-%% decode. #diameter_avp{} can only be set in a reply for encode.
+%% select/4
 
-select(#diameter_avp{} = A, {RC, As}, _) ->
-    {RC, [A|As]};
+select(E, [{RC, _} = T | Es], Dict0, Avps) ->
+    select(E, RC, T, Es, Dict0, Avps);
 
-select(_, {RC, _} = Acc, _)
-  when is_integer(RC) ->
-    Acc;
+select(E, [#diameter_avp{} = A | Es], Dict0, Avps) ->
+    select(E, Es, Dict0, [A | Avps]);
 
-select({RC, #diameter_avp{} = A}, {IsAns, As} = Acc, Dict0)
-  when is_integer(RC) ->
-    case is_result(RC, IsAns, Dict0) of
-        true  -> {RC, [A|As]};
-        false -> Acc
-    end;
+select(E, [RC | Es], Dict0, Avps) ->
+    select(E, RC, RC, Es, Dict0, Avps);
 
-select(RC, {IsAns, As} = Acc, Dict0)
-  when is_boolean(IsAns), is_integer(RC) ->
-    case is_result(RC, IsAns, Dict0) of
-        true  -> {RC, As};
-        false -> Acc
-    end.
+select(_, [], _, Avps) ->
+    Avps.
 
-%% reset/4
+%% select/6
+
+select(E, RC, T, _, Dict0, Avps)
+  when E, 3000 =< RC, RC < 4000;                 %% E-bit with 3xxx
+       E, ?BASE /= Dict0, 5000 =< RC, RC < 6000; %% E-bit with 5xxx
+       not E, RC < 3000 orelse 4000 =< RC ->     %% no E-bit
+    [T | Avps];
 
-reset(Msg, Dict, RC, Avps) ->
-    FailedAVP = failed_avp(Msg, Avps, Dict),
-    ResultCode = rc(Msg, RC, Dict),
-    set(set(Msg, FailedAVP, Dict), ResultCode, Dict).
+select(E, _, _, Es, Dict0, Avps) ->
+    select(E, Es, Dict0, Avps).
 
 %% eval_packet/2
 
 eval_packet(Pkt, Fs) ->
     lists:foreach(fun(F) -> diameter_lib:eval([F,Pkt]) end, Fs).
 
-%% make_answer_packet/2
+%% make_answer_packet/4
 
 %% Use decode errors to set Result-Code and/or Failed-AVP unless the
 %% the errors field has been explicitly set. Unfortunately, the
 %% default value is the empty list rather than 'undefined' so use the
 %% atom 'false' for "set nothing". (This is historical and changing
-%% the default value would require modules including diameter.hrl to
-%% be recompiled.)
-make_answer_packet(#diameter_packet{errors = []}
-                   = Pkt,
-                   #diameter_packet{errors = [_|_] = Es}
-                   = ReqPkt) ->
-    make_answer_packet(Pkt#diameter_packet{errors = Es}, ReqPkt);
+%% the default value would impact anyone expecting relying on the old
+%% default.)
 
-%% A reply message clears the R and T flags and retains the P flag.
-%% The E flag will be set at encode. 6.2 of 3588 requires the same P
-%% flag on an answer as on the request. A #diameter_packet{} returned
-%% from a handle_request callback can circumvent this by setting its
-%% own header values.
 make_answer_packet(#diameter_packet{header = Hdr,
                                     msg = Msg,
                                     errors = Es,
                                     transport_data = TD},
-                   #diameter_packet{header = ReqHdr}) ->
-    Hdr0 = ReqHdr#diameter_header{version = ?DIAMETER_VERSION,
-                                  is_request = false,
-                                  is_error = undefined,
-                                  is_retransmitted = false},
-    #diameter_packet{header = fold_record(Hdr0, Hdr),
-                     msg = Msg,
-                     errors = Es,
+                   #diameter_packet{header = Hdr0,
+                                    errors = Es0},
+                   MsgDict,
+                   Dict0) ->
+    #diameter_packet{header = make_answer_header(Hdr0, Hdr),
+                     msg = reset(Msg, Es0, Es, MsgDict, Dict0),
                      transport_data = TD};
 
 %% Binaries and header/avp lists are sent as-is.
-make_answer_packet(Bin, #diameter_packet{transport_data = TD})
+make_answer_packet(Bin, #diameter_packet{transport_data = TD}, _, _)
   when is_binary(Bin) ->
     #diameter_packet{bin = Bin,
                      transport_data = TD};
 make_answer_packet([#diameter_header{} | _] = Msg,
-                   #diameter_packet{transport_data = TD}) ->
+                   #diameter_packet{transport_data = TD},
+                   _,
+                   _) ->
     #diameter_packet{msg = Msg,
                      transport_data = TD};
 
-%% Otherwise, preserve transport_data.
-make_answer_packet(Msg, #diameter_packet{transport_data = TD} = Pkt) ->
-    make_answer_packet(#diameter_packet{msg = Msg, transport_data = TD}, Pkt).
+make_answer_packet(Msg,
+                   #diameter_packet{header = Hdr,
+                                    errors = Es,
+                                    transport_data = TD},
+                   MsgDict,
+                   Dict0) ->
+    #diameter_packet{header = make_answer_header(Hdr, undefined),
+                     msg = reset(Msg, [], Es, MsgDict, Dict0),
+                     transport_data = TD}.
+
+%% make_answer_header/2
+
+%% A reply message clears the R and T flags and retains the P flag.
+%% The E flag will be set at encode. 6.2 of 3588 requires the same P
+%% flag on an answer as on the request. A #diameter_packet{} returned
+%% from a handle_request callback can circumvent this by setting its
+%% own header values.
+make_answer_header(ReqHdr, Hdr) ->
+    Hdr0 = ReqHdr#diameter_header{version = ?DIAMETER_VERSION,
+                                  is_request = false,
+                                  is_error = undefined,
+                                  is_retransmitted = false},
+    fold_record(Hdr0, Hdr).
+
+%% reset/5
+
+reset(Msg, [_|_] = Es0, [] = Es, MsgDict, Dict0) ->
+    reset(Msg, Es, Es0, MsgDict, Dict0);
+
+reset(Msg, _, Es, _, _)
+  when Es == false;
+       Es == [] ->
+    Msg;
+
+reset(Msg, _, Es, MsgDict, Dict0) ->
+    E = is_answer_message(Msg, Dict0),
+    reset(Msg, select_error(E, Es, Dict0), choose(E, Dict0, MsgDict)).
+
+%% reset/4
+%%
+%% Set Result-Code and/or Failed-AVP (maybe). Only RC and {RC, AVP}
+%% are the result of decode. AVP or {RC, [AVP]} can be set in an
+%% answer for encode, as a convenience for injecting additional AVPs
+%% into Failed-AVP; eg. 5001 = DIAMETER_AVP_UNSUPPORTED.
+
+reset(Msg, [], _) ->
+    Msg;
+
+reset(Msg, [{RC, As} | Avps], Dict)
+  when is_list(As) ->
+    reset(Msg, [RC | As ++ Avps], Dict);
+
+reset(Msg, [{RC, Avp} | Avps], Dict) ->
+    reset(Msg, [RC, Avp | Avps], Dict);
+
+reset(Msg, [#diameter_avp{} | _] = Avps, Dict) ->
+    set(Msg, failed_avp(Msg, Avps, Dict), Dict);
+
+reset(Msg, [RC | Avps], Dict) ->
+    set(Msg, rc(Msg, RC, Dict) ++ failed_avp(Msg, Avps, Dict), Dict).
+
+%% set/3
 
 %% Reply as name and tuple list ...
 set([_|_] = Ans, Avps, _) ->
@@ -835,11 +878,7 @@ set(Rec, Avps, Dict) ->
 %%
 %% Turn the result code into a list if its optional and only set it if
 %% the arity is 1 or {0,1}. In other cases (which probably shouldn't
-%% exist in practise) we can't know what's appropriate.
-
-rc(_, B, _)
-  when is_boolean(B) ->
-    [];
+%% exist in practice) we can't know what's appropriate.
 
 rc([MsgName | _], RC, Dict) ->
     K = 'Result-Code',
@@ -857,8 +896,8 @@ rc(Rec, RC, Dict) ->
 failed_avp(_, [] = No, _) ->
     No;
 
-failed_avp(Rec, Avps, Dict) ->
-    [failed(Rec, [{'AVP', Avps}], Dict)].
+failed_avp(Msg, [_|_] = Avps, Dict) ->
+    [failed(Msg, [{'AVP', Avps}], Dict)].
 
 %% Reply as name and tuple list ...
 failed([MsgName | Values], FailedAvp, Dict) ->
@@ -955,22 +994,26 @@ failed(Rec, FailedAvp, Dict) ->
 %%    Error-Message AVP is not intended to be useful in real-time, and
 %%    SHOULD NOT be expected to be parsed by network entities.
 
-%% answer_message/5
+%% answer_message/4
 
-answer_message(OH, OR, RC, Dict0, #diameter_packet{avps = Avps,
-                                                   errors = Es}) ->
+answer_message(RC,
+               Dict0,
+               #diameter_caps{origin_host  = {OH,_},
+                              origin_realm = {OR,_}},
+               #diameter_packet{avps = Avps,
+                                errors = Es}) ->
     {Code, _, Vid} = Dict0:avp_header('Session-Id'),
     ['answer-message', {'Origin-Host', OH},
                        {'Origin-Realm', OR},
                        {'Result-Code', RC}]
-        ++ session_id(Code, Vid, Dict0, Avps)
+        ++ session_id(Code, Vid, Avps)
         ++ failed_avp(RC, Es).
 
-session_id(Code, Vid, Dict0, Avps)
+session_id(Code, Vid, Avps)
   when is_list(Avps) ->
     try
         #diameter_avp{data = Bin} = find_avp(Code, Vid, Avps),
-        [{'Session-Id', [Dict0:avp(decode, Bin, 'Session-Id')]}]
+        [{'Session-Id', [Bin]}]
     catch
         error: _ ->
             []
@@ -1190,8 +1233,6 @@ get_result(Dict, Msg) ->
     try
         [throw(A) || N <- ['Result-Code', 'Experimental-Result'],
                      #diameter_avp{} = A <- [get_avp(Dict, N, Msg)]]
-    of
-        [] -> false
     catch
         #diameter_avp{} = A -> A
     end.
@@ -1253,11 +1294,10 @@ answer_rc(_, _, Sent) ->
 %%
 %% In the process spawned for the outgoing request.
 
-send_R(SvcName, AppOrAlias, Msg, Opts, Caller) ->
-    case pick_peer(SvcName, AppOrAlias, Msg, Opts) of
-        {Transport, Mask, SvcOpts} ->
-            diameter_codec:setopts(SvcOpts),
-            send_request(Transport, Mask, Msg, Opts, Caller, SvcName);
+send_R(SvcName, AppOrAlias, Msg, CallOpts, Caller) ->
+    case pick_peer(SvcName, AppOrAlias, Msg, CallOpts) of
+        {{_,_} = Transport, SvcOpts} ->
+            send_request(Transport, SvcOpts, Msg, CallOpts, Caller, SvcName);
         {error, _} = No ->
             No
     end.
@@ -1265,27 +1305,36 @@ send_R(SvcName, AppOrAlias, Msg, Opts, Caller) ->
 %% make_options/1
 
 make_options(Options) ->
-    lists:foldl(fun mo/2, #options{}, Options).
+    make_opts(Options, false, [], none, 5000).
+
+%% Do our own recursion since this is faster than a lists:foldl/3
+%% setting elements in an #options{} accumulator.
+
+make_opts([], Detach, Extra, Filter, Tmo) ->
+    #options{detach = Detach,
+             extra = Extra,
+             filter = Filter,
+             timeout = Tmo};
 
-mo({timeout, T}, Rec)
-  when is_integer(T), 0 =< T ->
-    Rec#options{timeout = T};
+make_opts([{timeout, Tmo} | Rest], Detach, Extra, Filter, _)
+  when is_integer(Tmo), 0 =< Tmo ->
+    make_opts(Rest, Detach, Extra, Filter, Tmo);
 
-mo({filter, F}, #options{filter = none} = Rec) ->
-    Rec#options{filter = F};
-mo({filter, F}, #options{filter = {all, Fs}} = Rec) ->
-    Rec#options{filter = {all, [F | Fs]}};
-mo({filter, F}, #options{filter = F0} = Rec) ->
-    Rec#options{filter = {all, [F0, F]}};
+make_opts([{filter, F} | Rest], Detach, Extra, none, Tmo) ->
+    make_opts(Rest, Detach, Extra, F, Tmo);
+make_opts([{filter, F} | Rest], Detach, Extra, {all, Fs}, Tmo) ->
+    make_opts(Rest, Detach, Extra, {all, [F|Fs]}, Tmo);
+make_opts([{filter, F} | Rest], Detach, Extra, F0, Tmo) ->
+    make_opts(Rest, Detach, Extra, {all, [F0, F]}, Tmo);
 
-mo({extra, L}, #options{extra = X} = Rec)
+make_opts([{extra, L} | Rest], Detach, Extra, Filter, Tmo)
   when is_list(L) ->
-    Rec#options{extra = X ++ L};
+    make_opts(Rest, Detach, Extra ++ L, Filter, Tmo);
 
-mo(detach, Rec) ->
-    Rec#options{detach = true};
+make_opts([detach | Rest], _, Extra, Filter, Tmo) ->
+    make_opts(Rest, true, Extra, Filter, Tmo);
 
-mo(T, _) ->
+make_opts([T | _], _, _, _, _) ->
     ?ERROR({invalid_option, T}).
 
 %% ---------------------------------------------------------------------------
@@ -1302,44 +1351,51 @@ mo(T, _) ->
 %% The module field of the #diameter_app{} here includes any extra
 %% arguments passed to diameter:call/4.
 
-send_request({TPid, Caps, App}
+send_request({{TPid, _Caps} = TC, App}
              = Transport,
-             Mask,
-             Msg,
-             Opts,
+             #{sequence := Mask}
+             = SvcOpts,
+             Msg0,
+             CallOpts,
              Caller,
              SvcName) ->
-    Pkt = make_prepare_packet(Mask, Msg),
-
-    send_R(cb(App, prepare_request, [Pkt, SvcName, {TPid, Caps}]),
-           Pkt,
-           Transport,
-           Opts,
-           Caller,
-           SvcName,
-           []).
+    Pkt = make_prepare_packet(Mask, Msg0),
+
+    case prepare(cb(App, prepare_request, [Pkt, SvcName, TC]), []) of
+        [Msg | Fs] ->
+            ReqPkt = make_request_packet(Msg, Pkt),
+            EncPkt = encode(App#diameter_app.dictionary,
+                            TPid,
+                            SvcOpts,
+                            ReqPkt),
+            eval_packet(EncPkt, Fs),
+            T = send_R(ReqPkt, EncPkt, Transport, CallOpts, Caller, SvcName),
+            Ans = recv_answer(SvcName, App, CallOpts, T),
+            handle_answer(SvcName, SvcOpts, App, Ans);
+        {discard, Reason} ->
+            {error, Reason};
+        discard ->
+            {error, discarded};
+        {error, Reason} ->
+            ?ERROR({invalid_return, Reason, prepare_request, App})
+    end.
 
-%% send_R/7
+%% prepare/2
 
-send_R({send, Msg}, Pkt, Transport, Opts, Caller, SvcName, Fs) ->
-    send_R(make_request_packet(Msg, Pkt),
-           Transport,
-           Opts,
-           Caller,
-           SvcName,
-           Fs);
+prepare({send, Msg}, Fs) ->
+    [Msg | Fs];
 
-send_R({discard, Reason} , _, _, _, _, _, _) ->
-    {error, Reason};
+prepare({eval_packet, RC, F}, Fs) ->
+    prepare(RC, [F|Fs]);
 
-send_R(discard, _, _, _, _, _, _) ->
-    {error, discarded};
+prepare({discard, _Reason} = RC, _) ->
+    RC;
 
-send_R({eval_packet, RC, F}, Pkt, T, Opts, Caller, SvcName, Fs) ->
-    send_R(RC, Pkt, T, Opts, Caller, SvcName, [F|Fs]);
+prepare(discard = RC, _) ->
+    RC;
 
-send_R(E, _, {_, _, App}, _, _, _, _) ->
-    ?ERROR({invalid_return, E, prepare_request, App}).
+prepare(Reason, _) ->
+    {error, Reason}.
 
 %% make_prepare_packet/2
 %%
@@ -1359,43 +1415,39 @@ make_prepare_packet(Mask, #diameter_packet{msg = [#diameter_header{} = Hdr
 make_prepare_packet(Mask, #diameter_packet{header = Hdr} = Pkt) ->
     Pkt#diameter_packet{header = make_prepare_header(Mask, Hdr)};
 
+make_prepare_packet(Mask, [#diameter_header{} = Hdr | Avps]) ->
+    #diameter_packet{msg = [make_prepare_header(Mask, Hdr) | Avps]};
+
 make_prepare_packet(Mask, Msg) ->
-    make_prepare_packet(Mask, #diameter_packet{msg = Msg}).
+    #diameter_packet{header = make_prepare_header(Mask, undefined),
+                     msg = Msg}.
 
 %% make_prepare_header/2
 
 make_prepare_header(Mask, undefined) ->
     Seq = diameter_session:sequence(Mask),
-    make_prepare_header(#diameter_header{end_to_end_id = Seq,
-                                         hop_by_hop_id = Seq});
-
-make_prepare_header(Mask, #diameter_header{end_to_end_id = undefined,
-                                           hop_by_hop_id = undefined}
-                          = H) ->
-    Seq = diameter_session:sequence(Mask),
-    make_prepare_header(H#diameter_header{end_to_end_id = Seq,
-                                          hop_by_hop_id = Seq});
-
-make_prepare_header(Mask, #diameter_header{end_to_end_id = undefined} = H) ->
-    Seq = diameter_session:sequence(Mask),
-    make_prepare_header(H#diameter_header{end_to_end_id = Seq});
-
-make_prepare_header(Mask, #diameter_header{hop_by_hop_id = undefined} = H) ->
-    Seq = diameter_session:sequence(Mask),
-    make_prepare_header(H#diameter_header{hop_by_hop_id = Seq});
-
-make_prepare_header(_, Hdr) ->
-    make_prepare_header(Hdr).
-
-%% make_prepare_header/1
-
-make_prepare_header(#diameter_header{version = undefined} = Hdr) ->
-    make_prepare_header(Hdr#diameter_header{version = ?DIAMETER_VERSION});
-
-make_prepare_header(#diameter_header{} = Hdr) ->
-    Hdr;
-
-make_prepare_header(T) ->
+    #diameter_header{version = ?DIAMETER_VERSION,
+                     end_to_end_id = Seq,
+                     hop_by_hop_id = Seq};
+
+make_prepare_header(Mask, #diameter_header{version = V,
+                                           end_to_end_id = EI,
+                                           hop_by_hop_id = HI}
+                          = H)
+  when EI == undefined;
+       HI == undefined ->
+    Id = diameter_session:sequence(Mask),
+    H#diameter_header{version = ?DEFAULT(V, ?DIAMETER_VERSION),
+                      end_to_end_id = ?DEFAULT(EI, Id),
+                      hop_by_hop_id = ?DEFAULT(HI, Id)};
+
+make_prepare_header(_, #diameter_header{version = undefined} = H) ->
+    H#diameter_header{version = ?DIAMETER_VERSION};
+
+make_prepare_header(_, #diameter_header{} = H) ->
+    H;
+
+make_prepare_header(_, T) ->
     ?ERROR({invalid_header, T}).
 
 %% make_request_packet/2
@@ -1439,42 +1491,45 @@ make_retransmit_header(Hdr) ->
     Hdr#diameter_header{is_retransmitted = true}.
 
 %% fold_record/2
+%%
+%% Replace elements in the first record by those in the second that
+%% differ from undefined.
 
-fold_record(undefined, R) ->
-    R;
-fold_record(Rec, R) ->
-    diameter_lib:fold_tuple(2, Rec, R).
+fold_record(Rec0, undefined) ->
+    Rec0;
+fold_record(Rec0, Rec) ->
+    list_to_tuple(fold(tuple_to_list(Rec0), tuple_to_list(Rec))).
+
+fold([], []) ->
+    [];
+fold([H | T0], [undefined | T]) ->
+    [H | fold(T0, T)];
+fold([_ | T0], [H | T]) ->
+    [H | fold(T0, T)].
 
 %% send_R/6
 
-send_R(Pkt0,
-       {TPid, Caps, #diameter_app{dictionary = AppDict} = App},
-       Opts,
+send_R(ReqPkt,
+       EncPkt,
+       {{TPid, _Caps} = TC, #diameter_app{dictionary = AppDict}},
+       #options{timeout = Timeout},
        {Pid, Ref},
-       SvcName,
-       Fs) ->
-    Pkt = encode(AppDict, TPid, Pkt0, Fs),
-
-    #options{timeout = Timeout}
-        = Opts,
-
+       SvcName) ->
     Req = #request{ref = Ref,
                    caller = Pid,
                    handler = self(),
-                   transport = TPid,
-                   caps = Caps,
-                   packet = Pkt0},
+                   peer = TC,
+                   packet = ReqPkt},
 
-    incr(send, Pkt, TPid, AppDict),
-    {TRef, MRef} = zend_requezt(TPid, Pkt, Req, SvcName, Timeout),
+    incr(send, EncPkt, TPid, AppDict),
+    {TRef, MRef} = zend_requezt(TPid, EncPkt, Req, SvcName, Timeout),
     Pid ! Ref,  %% tell caller a send has been attempted
-    handle_answer(SvcName,
-                  App,
-                  recv_A(Timeout, SvcName, App, Opts, {TRef, MRef, Req})).
+    {TRef, MRef, Req}.
 
-%% recv_A/5
+%% recv_answer/4
 
-recv_A(Timeout, SvcName, App, Opts, {TRef, MRef, #request{ref = Ref} = Req}) ->
+recv_answer(SvcName, App, CallOpts, {TRef, MRef, #request{ref = Ref}
+                                                 = Req}) ->
     %% Matching on TRef below ensures we ignore messages that pertain
     %% to a previous transport prior to failover. The answer message
     %% includes the pid of the transport on which it was received,
@@ -1485,97 +1540,90 @@ recv_A(Timeout, SvcName, App, Opts, {TRef, MRef, #request{ref = Ref} = Req}) ->
         {timeout = Reason, TRef, _} ->        %% No timely reply
             {error, Req, Reason};
         {'DOWN', MRef, process, _, _} when false /= MRef -> %% local peer_down
-            failover(SvcName, App, Req, Opts, Timeout);
+            failover(SvcName, App, Req, CallOpts);
         {failover, TRef} ->                   %% local or remote peer_down
-            failover(SvcName, App, Req, Opts, Timeout)
+            failover(SvcName, App, Req, CallOpts)
     end.
 
-%% failover/5
+%% failover/4
 
-failover(SvcName, App, Req, Opts, Timeout) ->
-    retransmit(pick_peer(SvcName, App, Req, Opts),
-               Req,
-               Opts,
-               SvcName,
-               Timeout).
+failover(SvcName, App, Req, CallOpts) ->
+    resend_request(pick_peer(SvcName, App, Req, CallOpts),
+                   Req,
+                   CallOpts,
+                   SvcName).
 
-%% handle_answer/3
+%% handle_answer/4
 
-handle_answer(SvcName, App, {error, Req, Reason}) ->
-    handle_error(App, Req, Reason, SvcName);
+handle_answer(SvcName, _, App, {error, Req, Reason}) ->
+    #request{packet = Pkt,
+             peer = {_TPid, _Caps} = TC}
+        = Req,
+    cb(App, handle_error, [Reason, msg(Pkt), SvcName, TC]);
 
 handle_answer(SvcName,
-              #diameter_app{dictionary = AppDict,
-                            id = Id}
+              SvcOpts,
+              #diameter_app{id = Id,
+                            dictionary = AppDict,
+                            options = [{answer_errors, AE} | _]}
               = App,
               {answer, Req, Dict0, Pkt}) ->
     MsgDict = msg_dict(AppDict, Dict0, Pkt),
-    handle_A(errors(Id, diameter_codec:decode({MsgDict, AppDict}, Pkt)),
-             SvcName,
-             MsgDict,
-             Dict0,
-             App,
-             Req).
-
-%% We don't really need to do a full decode if we're a relay and will
-%% just resend with a new hop by hop identifier, but might a proxy
-%% want to examine the answer?
-
-handle_A(Pkt, SvcName, Dict, Dict0, App, #request{transport = TPid} = Req) ->
-    AppDict = App#diameter_app.dictionary,
-
-    incr(recv, Pkt, TPid, AppDict),
-
-    try
-        incr_result(recv, Pkt, TPid, {Dict, AppDict, Dict0}) %% count incoming
-    of
-        _ -> answer(Pkt, SvcName, App, Req)
-    catch
-        exit: {no_result_code, _} ->
-            %% RFC 6733 requires one of Result-Code or
-            %% Experimental-Result, but the decode will have detected
-            %% a missing AVP. If both are optional in the dictionary
-            %% then this isn't a decode error: just continue on.
-            answer(Pkt, SvcName, App, Req);
-        exit: {invalid_error_bit, {_, _, _, Avp}} ->
-            #diameter_packet{errors = Es}
-                = Pkt,
-            E = {5004, Avp},
-            answer(Pkt#diameter_packet{errors = [E|Es]}, SvcName, App, Req)
-    end.
-
-%% answer/4
-
-answer(Pkt,
-       SvcName,
-       #diameter_app{module = ModX,
-                     options = [{answer_errors, AE} | _]},
-       Req) ->
-    a(Pkt, SvcName, ModX, AE, Req).
-
--spec a(_, _, _) -> no_return().  %% silence dialyzer
-
-a(#diameter_packet{errors = Es}
-  = Pkt,
-  SvcName,
-  ModX,
-  AE,
-  #request{transport = TPid,
-           caps = Caps,
-           packet = P})
-  when [] == Es;
-       callback == AE ->
-    cb(ModX, handle_answer, [Pkt, msg(P), SvcName, {TPid, Caps}]);
-
-a(Pkt, SvcName, _, AE, _) ->
-    a(Pkt#diameter_packet.header, SvcName, AE).
-
-a(Hdr, SvcName, report) ->
+    DecPkt = errors(Id, diameter_codec:decode({MsgDict, AppDict},
+                                              SvcOpts,
+                                              Pkt)),
+    #request{peer = {TPid, _}}
+        = Req,
+
+    incr(recv, DecPkt, TPid, AppDict),
+
+    AnsPkt = try
+                 incr_result(recv, DecPkt, TPid, {MsgDict, AppDict, Dict0})
+             of
+                 _ -> DecPkt
+             catch
+                 exit: {no_result_code, _} ->
+                     %% RFC 6733 requires one of Result-Code or
+                     %% Experimental-Result, but the decode will have
+                     %% detected a missing AVP. If both are optional in
+                     %% the dictionary then this isn't a decode error:
+                     %% just continue on.
+                     DecPkt;
+                 exit: {invalid_error_bit, {_, _, _, Avp}} ->
+                     #diameter_packet{errors = Es}
+                         = DecPkt,
+                     E = {5004, Avp},
+                     DecPkt#diameter_packet{errors = [E|Es]}
+             end,
+
+    handle_answer(AnsPkt, SvcName, App, AE, Req).
+
+%% handle_answer/5
+
+handle_answer(#diameter_packet{errors = Es}
+              = Pkt,
+              SvcName,
+              App,
+              AE,
+              #request{peer = {_TPid, _Caps} = TC,
+                       packet = P})
+  when callback == AE;
+       [] == Es ->
+    cb(App, handle_answer, [Pkt, msg(P), SvcName, TC]);
+
+handle_answer(#diameter_packet{header = H}, SvcName, _, AE, _) ->
+    handle_error(H, SvcName, AE).
+
+%% handle_error/3
+
+-spec handle_error(_, _, _) -> no_return().  %% silence dialyzer
+
+handle_error(Hdr, SvcName, report) ->
     MFA = {?MODULE, handle_answer, [SvcName, Hdr]},
     diameter_lib:warning_report(errors, MFA),
-    a(Hdr, SvcName, discard);
+    handle_error(Hdr, SvcName, discard);
 
-a(Hdr, SvcName, discard) ->
+handle_error(Hdr, SvcName, discard) ->
     x({answer_errors, {SvcName, Hdr}}).
 
 %% Note that we don't check that the application id in the answer's
@@ -1586,16 +1634,38 @@ a(Hdr, SvcName, discard) ->
 %% timer value is ignored. This means that an answer could be accepted
 %% from a peer after timeout in the case of failover.
 
-%% retransmit/5
+%% resend_request/4
 
-retransmit({{_,_,App} = Transport, _, _}, Req, Opts, SvcName, Timeout) ->
-    try retransmit(Transport, Req, SvcName, Timeout) of
-        T -> recv_A(Timeout, SvcName, App, Opts, T)
-    catch
-        ?FAILURE(Reason) -> {error, Req, Reason}
+resend_request({{{TPid, _Caps} = TC, App}, SvcOpts},
+               Req0,
+               #options{timeout = Timeout}
+               = CallOpts,
+               SvcName) ->
+    case
+        undefined == get(TPid)
+        andalso prepare_retransmit(TC, App, Req0, SvcName)
+    of
+        [ReqPkt | Fs] ->
+            AppDict = App#diameter_app.dictionary,
+            EncPkt = encode(AppDict, TPid, SvcOpts, ReqPkt),
+            eval_packet(EncPkt, Fs),
+            Req = Req0#request{peer = TC,
+                               packet = ReqPkt},
+            ?LOG(retransmission, EncPkt#diameter_packet.header),
+            incr(TPid, {msg_id(EncPkt, AppDict), send, retransmission}),
+            {TRef, MRef} = zend_requezt(TPid, EncPkt, Req, SvcName, Timeout),
+            recv_answer(SvcName, App, CallOpts, {TRef, MRef, Req});
+        false ->
+            {error, Req0, timeout};
+        {discard, Reason} ->
+            {error, Req0, Reason};
+        discard ->
+            {error, Req0, discarded};
+        {error, T} ->
+            ?ERROR({invalid_return, T, prepare_retransmit, App})
     end;
 
-retransmit(_, Req, _, _, _) ->  %% no alternate peer
+resend_request(_, Req, _, _) ->  %% no alternate peer
     {error, Req, failover}.
 
 %% pick_peer/4
@@ -1605,8 +1675,8 @@ retransmit(_, Req, _, _, _) ->  %% no alternate peer
 pick_peer(SvcName,
           App,
           #request{packet = #diameter_packet{msg = Msg}},
-          Opts) ->
-    pick_peer(SvcName, App, Msg, Opts#options{extra = []});
+          CallOpts) ->
+    pick_peer(SvcName, App, Msg, CallOpts#options{extra = []});
 
 pick_peer(_, _, undefined, _) ->
     {error, no_connection};
@@ -1615,27 +1685,13 @@ pick_peer(SvcName,
           AppOrAlias,
           Msg,
           #options{filter = Filter, extra = Xtra}) ->
-    pick(diameter_service:pick_peer(SvcName,
-                                    AppOrAlias,
-                                    {fun(D) -> get_destination(D, Msg) end,
-                                     Filter,
-                                     Xtra})).
-
-pick(false) ->
-    {error, no_connection};
-
-pick(T) ->
-    T.
-
-%% handle_error/4
-
-handle_error(App,
-             #request{packet = Pkt,
-                      transport = TPid,
-                      caps = Caps},
-             Reason,
-             SvcName) ->
-    cb(App, handle_error, [Reason, msg(Pkt), SvcName, {TPid, Caps}]).
+    X = {fun(D) -> get_destination(D, Msg) end, Filter, Xtra},
+    case diameter_service:pick_peer(SvcName, AppOrAlias, X) of
+        false ->
+            {error, no_connection};
+        T ->
+            T
+    end.
 
 msg(#diameter_packet{msg = undefined, bin = Bin}) ->
     Bin;
@@ -1644,27 +1700,20 @@ msg(#diameter_packet{msg = Msg}) ->
 
 %% encode/4
 
-encode(Dict, TPid, Pkt, Fs) ->
-    P = encode(Dict, TPid, Pkt),
-    eval_packet(P, Fs),
-    P.
-
-%% encode/2
-
 %% Note that prepare_request can return a diameter_packet containing a
 %% header or transport_data. Even allow the returned record to contain
 %% an encoded binary. This isn't the usual case and doesn't properly
 %% support retransmission but is useful for test.
 
-encode(Dict, TPid, Pkt)
+encode(Dict, TPid, Opts, Pkt)
   when is_atom(Dict) ->
-    encode({Dict, Dict}, TPid, Pkt);
+    encode({Dict, Dict}, TPid, Opts, Pkt);
 
 %% A message to be encoded.
-encode(DictT, TPid, #diameter_packet{bin = undefined} = Pkt) ->
+encode(DictT, TPid, Opts, #diameter_packet{bin = undefined} = Pkt) ->
     {Dict, AppDict} = DictT,
     try
-        diameter_codec:encode(Dict, Pkt)
+        diameter_codec:encode(Dict, Opts, Pkt)
     catch
         exit: {diameter_codec, encode, T} = Reason ->
             incr_error(send, T, TPid, AppDict),
@@ -1672,7 +1721,7 @@ encode(DictT, TPid, #diameter_packet{bin = undefined} = Pkt) ->
     end;
 
 %% An encoded binary: just send.
-encode(_, _, #diameter_packet{} = Pkt) ->
+encode(_, _, _, #diameter_packet{} = Pkt) ->
     Pkt.
 
 %% zend_requezt/5
@@ -1743,71 +1792,21 @@ recv(TPid, Pid, TRef, {LocalTRef, MRef}) ->
 send(Pid, Pkt, Route) ->
     Pid ! {send, Pkt, Route}.
 
-%% retransmit/4
+%% prepare_retransmit/4
 
-retransmit({TPid, Caps, App}
-           = Transport,
-           #request{packet = Pkt0}
-           = Req,
-           SvcName,
-           Timeout) ->
-    undefined == get(TPid)       %% Don't failover to a peer we've
-        orelse ?THROW(timeout),  %% already sent to.
+prepare_retransmit({_TPid, _Caps} = TC, App, Req, SvcName) ->
+    Pkt = make_retransmit_packet(Req#request.packet),
 
-    Pkt = make_retransmit_packet(Pkt0),
+    case prepare(cb(App, prepare_retransmit, [Pkt, SvcName, TC]), []) of
+        [Msg | Fs] ->
+            [make_request_packet(Msg, Pkt) | Fs];
+        No ->
+            No
+    end.
 
-    retransmit(cb(App, prepare_retransmit, [Pkt, SvcName, {TPid, Caps}]),
-               Transport,
-               Req#request{packet = Pkt},
-               SvcName,
-               Timeout,
-               []).
 %% When sending a binary, it's up to prepare_retransmit to modify it
 %% accordingly.
 
-retransmit({send, Msg},
-           Transport,
-           #request{packet = Pkt}
-           = Req,
-           SvcName,
-           Timeout,
-           Fs) ->
-    resend_request(make_request_packet(Msg, Pkt),
-                   Transport,
-                   Req,
-                   SvcName,
-                   Timeout,
-                   Fs);
-
-retransmit({discard, Reason}, _, _, _, _, _) ->
-    ?THROW(Reason);
-
-retransmit(discard, _, _, _, _, _) ->
-    ?THROW(discarded);
-
-retransmit({eval_packet, RC, F}, Transport, Req, SvcName, Timeout, Fs) ->
-    retransmit(RC, Transport, Req, SvcName, Timeout, [F|Fs]);
-
-retransmit(T, {_, _, App}, _, _, _, _) ->
-    ?ERROR({invalid_return, T, prepare_retransmit, App}).
-
-resend_request(Pkt0,
-               {TPid, Caps, #diameter_app{dictionary = AppDict}},
-               Req0,
-               SvcName,
-               Tmo,
-               Fs) ->
-    Pkt = encode(AppDict, TPid, Pkt0, Fs),
-
-    Req = Req0#request{transport = TPid,
-                       packet = Pkt0,
-                       caps = Caps},
-
-    ?LOG(retransmission, Pkt#diameter_packet.header),
-    incr(TPid, {msg_id(Pkt, AppDict), send, retransmission}),
-    {TRef, MRef} = zend_requezt(TPid, Pkt, Req, SvcName, Tmo),
-    {TRef, MRef, Req}.
-
 %% peer_monitor/2
 
 peer_monitor(TPid, TRef) ->
@@ -1907,7 +1906,7 @@ ungroup(Avp) ->
 avp_decode(Dict, Name, #diameter_avp{value = undefined,
                                      data = Bin}
                        = Avp) ->
-    try Dict:avp(decode, Bin, Name) of
+    try Dict:avp(decode, Bin, Name, decode_opts(Dict)) of
         V ->
             Avp#diameter_avp{value = V}
     catch
@@ -1918,8 +1917,6 @@ avp_decode(_, _, #diameter_avp{} = Avp) ->
     Avp.
 
 cb(#diameter_app{module = [_|_] = M}, F, A) ->
-    eval(M, F, A);
-cb([_|_] = M, F, A) ->
     eval(M, F, A).
 
 eval([M|X], F, A) ->
@@ -1927,3 +1924,10 @@ eval([M|X], F, A) ->
 
 choose(true, X, _)  -> X;
 choose(false, _, X) -> X.
+
+%% Decode options sufficient for AVP extraction.
+decode_opts(Dict) ->
+    #{string_decode => false,
+      strict_mbit => false,
+      failed_avp => false,
+      dictionary => Dict}.
diff --git a/lib/diameter/src/base/diameter_types.erl b/lib/diameter/src/base/diameter_types.erl
index 6ecf385239..86b674dd48 100644
--- a/lib/diameter/src/base/diameter_types.erl
+++ b/lib/diameter/src/base/diameter_types.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2015. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -26,32 +26,16 @@
 %%
 
 %% Basic types.
--export(['OctetString'/2,
-         'Integer32'/2,
-         'Integer64'/2,
-         'Unsigned32'/2,
-         'Unsigned64'/2,
-         'Float32'/2,
-         'Float64'/2]).
-
-%% Derived types.
--export(['Address'/2,
-         'Time'/2,
-         'UTF8String'/2,
-         'DiameterIdentity'/2,
-         'DiameterURI'/2,
-         'IPFilterRule'/2,
-         'QoSFilterRule'/2]).
-
-%% Functions taking the AVP name in question as second parameter.
 -export(['OctetString'/3,
          'Integer32'/3,
          'Integer64'/3,
          'Unsigned32'/3,
          'Unsigned64'/3,
          'Float32'/3,
-         'Float64'/3,
-         'Address'/3,
+         'Float64'/3]).
+
+%% Derived types.
+-export(['Address'/3,
          'Time'/3,
          'UTF8String'/3,
          'DiameterIdentity'/3,
@@ -89,81 +73,80 @@
 %%    AVP Data Format is needed, a new version of this RFC must be created.
 %% --------------------
 
-'OctetString'(decode, Bin)
+'OctetString'(decode, Bin, #{string_decode := true})
   when is_binary(Bin) ->
-    case diameter_codec:getopt(string_decode) of
-        true ->
-            binary_to_list(Bin);
-        false ->
-            Bin
-    end;
-
-'OctetString'(decode, B) ->
+    binary_to_list(Bin);
+
+'OctetString'(decode, Bin, _)
+  when is_binary(Bin) ->
+    Bin;
+
+'OctetString'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'OctetString'(encode = M, zero) ->
-    'OctetString'(M, []);
+'OctetString'(encode, zero, _) ->
+    <<>>;
 
-'OctetString'(encode, Str) ->
+'OctetString'(encode, Str, _) ->
     iolist_to_binary(Str).
 
 %% --------------------
 
-'Integer32'(decode, <<X:32/signed>>) ->
+'Integer32'(decode, <<X:32/signed>>, _) ->
     X;
 
-'Integer32'(decode, B) ->
+'Integer32'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Integer32'(encode = M, zero) ->
-    'Integer32'(M, 0);
+'Integer32'(encode, zero, _) ->
+    <<0:32/signed>>;
 
-'Integer32'(encode, I)
+'Integer32'(encode, I, _)
   when ?SINT(32,I) ->
     <<I:32/signed>>.
 
 %% --------------------
 
-'Integer64'(decode, <<X:64/signed>>) ->
+'Integer64'(decode, <<X:64/signed>>, _) ->
     X;
 
-'Integer64'(decode, B) ->
+'Integer64'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Integer64'(encode = M, zero) ->
-    'Integer64'(M, 0);
+'Integer64'(encode, zero, _) ->
+    <<0:64/signed>>;
 
-'Integer64'(encode, I)
+'Integer64'(encode, I, _)
   when ?SINT(64,I) ->
     <<I:64/signed>>.
 
 %% --------------------
 
-'Unsigned32'(decode, <<X:32>>) ->
+'Unsigned32'(decode, <<X:32>>, _) ->
     X;
 
-'Unsigned32'(decode, B) ->
+'Unsigned32'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Unsigned32'(encode = M, zero) ->
-    'Unsigned32'(M, 0);
+'Unsigned32'(encode, zero, _) ->
+    <<0:32>>;
 
-'Unsigned32'(encode, I)
+'Unsigned32'(encode, I, _)
   when ?UINT(32,I) ->
     <<I:32>>.
 
 %% --------------------
 
-'Unsigned64'(decode, <<X:64>>) ->
+'Unsigned64'(decode, <<X:64>>, _) ->
     X;
 
-'Unsigned64'(decode, B) ->
+'Unsigned64'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Unsigned64'(encode = M, zero) ->
-    'Unsigned64'(M, 0);
+'Unsigned64'(encode, zero, _) ->
+    <<0:64>>;
 
-'Unsigned64'(encode, I)
+'Unsigned64'(encode, I, _)
   when ?UINT(64,I) ->
     <<I:64>>.
 
@@ -184,25 +167,25 @@
 %% arithmetic is performed on the decoded value. Better to be explicit
 %% that precision has been lost.
 
-'Float32'(decode, <<S:1, 255:8, _:23>>) ->
+'Float32'(decode, <<S:1, 255:8, _:23>>, _) ->
     choose(S, infinity, '-infinity');
 
-'Float32'(decode, <<X:32/float>>) ->
+'Float32'(decode, <<X:32/float>>, _) ->
     X;
 
-'Float32'(decode, B) ->
+'Float32'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Float32'(encode = M, zero) ->
-    'Float32'(M, 0.0);
+'Float32'(encode, zero, _) ->
+    <<0.0:32/float>>;
 
-'Float32'(encode, infinity) ->
+'Float32'(encode, infinity, _) ->
     <<0:1, 255:8, 0:23>>;
 
-'Float32'(encode, '-infinity') ->
+'Float32'(encode, '-infinity', _) ->
     <<1:1, 255:8, 0:23>>;
 
-'Float32'(encode, X)
+'Float32'(encode, X, _)
   when is_float(X) ->
     <<X:32/float>>.
 %% Note that this could also encode infinity/-infinity for large
@@ -222,25 +205,25 @@
 
 %% The 64 bit format is entirely analogous to the 32 bit format.
 
-'Float64'(decode, <<S:1, 2047:11, _:52>>) ->
+'Float64'(decode, <<S:1, 2047:11, _:52>>, _) ->
     choose(S, infinity, '-infinity');
 
-'Float64'(decode, <<X:64/float>>) ->
+'Float64'(decode, <<X:64/float>>, _) ->
     X;
 
-'Float64'(decode, B) ->
+'Float64'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Float64'(encode, infinity) ->
+'Float64'(encode, infinity, _) ->
     <<0:1, 2047:11, 0:52>>;
 
-'Float64'(encode, '-infinity') ->
+'Float64'(encode, '-infinity', _) ->
     <<1:1, 2047:11, 0:52>>;
 
-'Float64'(encode = M, zero) ->
-    'Float64'(M, 0.0);
+'Float64'(encode, zero, _) ->
+    <<0.0:64/float>>;
 
-'Float64'(encode, X)
+'Float64'(encode, X, _)
   when is_float(X) ->
     <<X:64/float>>.
 
@@ -256,18 +239,18 @@
 %%    format.
 %% --------------------
 
-'Address'(encode, zero) ->
+'Address'(encode, zero, _) ->
     <<0:48>>;
 
-'Address'(decode, <<A:16, B/binary>>)
+'Address'(decode, <<A:16, B/binary>>, _)
   when 1 == A,  4 == size(B);
        2 == A, 16 == size(B) ->
     list_to_tuple([N || <<N:A/unit:8>> <= B]);
 
-'Address'(decode, B) ->
+'Address'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Address'(encode, T) ->
+'Address'(encode, T, _) ->
     Ns = tuple_to_list(diameter_lib:ipaddr(T)),  %% length 4 or 8
     A = length(Ns) div 4,                        %% 1 or 2
     B = << <<N:A/unit:8>> || N <- Ns >>,
@@ -278,36 +261,38 @@
 %% A DiameterIdentity is a FQDN as definined in RFC 1035, which is at
 %% least one character.
 
-'DiameterIdentity'(encode = M, zero) ->
-    'OctetString'(M, [0]);
+'DiameterIdentity'(encode, zero, _) ->
+    <<0>>;
 
-'DiameterIdentity'(encode = M, X) ->
-    <<_,_/binary>> = 'OctetString'(M, X);
+'DiameterIdentity'(encode = M, X, Opts) ->
+    <<_,_/binary>> = 'OctetString'(M, X, Opts);
 
-'DiameterIdentity'(decode = M, <<_,_/binary>> = X) ->
-    'OctetString'(M, X);
+'DiameterIdentity'(decode = M, <<_,_/binary>> = X, Opts) ->
+    'OctetString'(M, X, Opts);
 
-'DiameterIdentity'(decode, X) ->
+'DiameterIdentity'(decode, X, _) ->
     ?INVALID_LENGTH(X).
 
 %% --------------------
 
-'DiameterURI'(decode, Bin)
+'DiameterURI'(decode, Bin, Opts)
   when is_binary(Bin) ->
-    scan_uri(Bin);
+    scan_uri(Bin, Opts);
 
-'DiameterURI'(decode, B) ->
+'DiameterURI'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
 %% The minimal DiameterURI is "aaa://x", 7 characters.
-'DiameterURI'(encode = M, zero) ->
-    'OctetString'(M, lists:duplicate(0,7));
-
-'DiameterURI'(encode, #diameter_uri{type = Type,
-                                    fqdn = DN,
-                                    port = PN,
-                                    transport = T,
-                                    protocol = P})
+'DiameterURI'(encode, zero, _) ->
+    <<0:7/unit:8>>;
+
+'DiameterURI'(encode,
+              #diameter_uri{type = Type,
+                            fqdn = DN,
+                            port = PN,
+                            transport = T,
+                            protocol = P},
+              _)
   when (Type == 'aaa' orelse Type == 'aaas'),
        is_integer(PN),
        0 =< PN,
@@ -324,48 +309,47 @@
 %% defaults, so it's best to be explicit. Interpret defaults on decode
 %% since there's no choice.
 
-'DiameterURI'(encode, Str) ->
+'DiameterURI'(encode, Str, Opts) ->
     Bin = iolist_to_binary(Str),
-    #diameter_uri{} = scan_uri(Bin),  %% assert
+    #diameter_uri{} = scan_uri(Bin, Opts),  %% assert
     Bin.
 
 %% --------------------
 
 %% This minimal rule is "deny in 0 from 0.0.0.0 to 0.0.0.0", 33 characters.
-'IPFilterRule'(encode = M, zero) ->
-    'OctetString'(M, lists:duplicate(0,33));
+'IPFilterRule'(encode, zero, _) ->
+    <<0:33/unit:8>>;
 
-'IPFilterRule'(M, X) ->
-    'OctetString'(M, X).
+'IPFilterRule'(M, X, Opts) ->
+    'OctetString'(M, X, Opts).
 
 %% --------------------
 
 %% This minimal rule is the same as for an IPFilterRule.
-'QoSFilterRule'(encode = M, zero = X) ->
-    'IPFilterRule'(M, X);
+'QoSFilterRule'(encode, zero, _) ->
+    <<0:33/unit:8>>;
 
-'QoSFilterRule'(M, X) ->
-    'OctetString'(M, X).
+'QoSFilterRule'(M, X, Opts) ->
+    'OctetString'(M, X, Opts).
 
 %% --------------------
 
-'UTF8String'(decode, Bin)
+'UTF8String'(decode, Bin, #{string_decode := true})
   when is_binary(Bin) ->
-    case diameter_codec:getopt(string_decode) of
-        true ->
-            %% assert list return
-            tl([0|_] = unicode:characters_to_list([0, Bin]));
-        false ->
-            <<_/binary>> = unicode:characters_to_binary(Bin)
-    end;
-
-'UTF8String'(decode, B) ->
+    %% assert list return
+    tl([0|_] = unicode:characters_to_list([0, Bin]));
+
+'UTF8String'(decode, Bin, _)
+  when is_binary(Bin) ->
+    <<_/binary>> = unicode:characters_to_binary(Bin);
+
+'UTF8String'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'UTF8String'(encode = M, zero) ->
-    'UTF8String'(M, []);
+'UTF8String'(encode, zero, _) ->
+    <<>>;
 
-'UTF8String'(encode, S) ->
+'UTF8String'(encode, S, _) ->
     <<_/binary>> = unicode:characters_to_binary(S).   %% assert binary return
 
 %% --------------------
@@ -414,67 +398,23 @@
 -define(TIME_MIN, {{1968,1,20},{3,14,8}}).  %% TIME_1900 + 1 bsl 31
 -define(TIME_MAX, {{2104,2,26},{9,42,24}}). %% TIME_2036 + 1 bsl 31
 
-'Time'(decode, <<Time:32>>) ->
+'Time'(decode, <<Time:32>>, _) ->
     Offset = msb(1 == Time bsr 31),
     calendar:gregorian_seconds_to_datetime(Time + Offset);
 
-'Time'(decode, B) ->
+'Time'(decode, B, _) ->
     ?INVALID_LENGTH(B);
 
-'Time'(encode, {{_Y,_M,_D},{_HH,_MM,_SS}} = Datetime)
+'Time'(encode, {{_Y,_M,_D},{_HH,_MM,_SS}} = Datetime, _)
   when ?TIME_MIN =< Datetime, Datetime < ?TIME_MAX ->
     S = calendar:datetime_to_gregorian_seconds(Datetime),
     T = S - msb(S < ?TIME_2036),
     0 = T bsr 32,  %% sanity check
     <<T:32>>;
 
-'Time'(encode, zero) ->
+'Time'(encode, zero, _) ->
     <<0:32>>.
 
-%% -------------------------------------------------------------------------
-
-'OctetString'(M, _, Data) ->
-    'OctetString'(M, Data).
-
-'Integer32'(M, _, Data) ->
-    'Integer32'(M, Data).
-
-'Integer64'(M, _, Data) ->
-    'Integer64'(M, Data).
-
-'Unsigned32'(M, _, Data) ->
-    'Unsigned32'(M, Data).
-
-'Unsigned64'(M, _, Data) ->
-    'Unsigned64'(M, Data).
-
-'Float32'(M, _, Data) ->
-    'Float32'(M, Data).
-
-'Float64'(M, _, Data) ->
-    'Float64'(M, Data).
-
-'Address'(M, _, Data) ->
-    'Address'(M, Data).
-
-'Time'(M, _, Data) ->
-    'Time'(M, Data).
-
-'UTF8String'(M, _, Data) ->
-    'UTF8String'(M, Data).
-
-'DiameterIdentity'(M, _, Data) ->
-    'DiameterIdentity'(M, Data).
-
-'DiameterURI'(M, _, Data) ->
-    'DiameterURI'(M, Data).
-
-'IPFilterRule'(M, _, Data) ->
-    'IPFilterRule'(M, Data).
-
-'QoSFilterRule'(M, _, Data) ->
-    'QoSFilterRule'(M, Data).
-
 %% ===========================================================================
 %% ===========================================================================
 
@@ -564,7 +504,7 @@ msb(false) -> ?TIME_2036.
 %%
 %%       aaa-protocol       = ( "diameter" / "radius" / "tacacs+" )
 
-scan_uri(Bin) ->
+scan_uri(Bin, Opts) ->
     RE = "^(aaas?)://"
          "([-a-zA-Z0-9.]{1,255})"
          "(:0{0,5}([0-9]{1,5}))?"
@@ -583,28 +523,30 @@ scan_uri(Bin) ->
                                         RE,
                                         [{capture, [1,2,4,6,8], binary}]),
     Type = to_atom(A),
-    {PN0, T0} = defaults(diameter_codec:getopt(rfc), Type),
-    PortNr = to_int(PN, PN0),
-    0 = PortNr bsr 16,  %% assert
     #diameter_uri{type = Type,
-                  fqdn = 'OctetString'(decode, DN),
-                  port = PortNr,
-                  transport = to_atom(T, T0),
+                  fqdn = 'OctetString'(decode, DN, Opts),
+                  port = portnr(PN, Type, Opts),
+                  transport = transport(T, Opts),
                   protocol = to_atom(P, diameter)}.
 
 %% Choose defaults based on the RFC, since 6733 has changed them.
-defaults(3588, _) ->
-    {3868, sctp};
-defaults(6733, aaa) ->
-    {3868, tcp};
-defaults(6733, aaas) ->
-    {5658, tcp}.
-
-to_int(<<>>, N) ->
-    N;
-to_int(B, _) ->
+
+portnr(<<>>, aaa, #{rfc := 6733}) ->
+    3868;
+portnr(<<>>, aaas, #{rfc := 6733}) ->
+    5868;
+portnr(<<>>, _, #{rfc := 3588}) ->
+    3868;
+portnr(B, _, _) ->
     binary_to_integer(B).
 
+transport(<<>>, #{rfc := 6733}) ->
+    tcp;
+transport(<<>>, #{rfc := 3588}) ->
+    sctp;
+transport(B, _) ->
+    to_atom(B).
+
 to_atom(<<>>, A) ->
     A;
 to_atom(B, _) ->
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index a2eb661870..a63425d92a 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -50,10 +50,6 @@
 
 -define(IS_NATURAL(N), (is_integer(N) andalso 0 =< N)).
 
--record(config,
-        {suspect = 1 :: non_neg_integer(),    %% OKAY -> SUSPECT
-         okay    = 3 :: non_neg_integer()}).  %% REOPEN -> OKAY
-
 -record(watchdog,
         {%% PCB - Peer Control Block; see RFC 3539, Appendix A
          status = initial :: initial | okay | suspect | down | reopen,
@@ -70,12 +66,19 @@
                | integer()        %% monotonic time
                | undefined,
          dictionary :: module(),  %% common dictionary
-         receive_data :: term(),
-                 %% term passed into diameter_service with incoming message
-         sequence :: diameter:sequence(),     %% mask
-         restrict :: {diameter:restriction(), boolean()},
-         shutdown = false :: boolean(),
-         config :: #config{}}).
+         receive_data :: term(),  %% term passed with incoming message
+         config :: #{sequence := diameter:sequence(),  %% mask
+                     restrict_connections := diameter:restriction(),
+                     restrict := boolean(),
+                     suspect := non_neg_integer(), %% OKAY -> SUSPECT
+                     okay := non_neg_integer()},   %% REOPEN -> OKAY
+         codec :: #{string_decode := false,
+                    strict_mbit := boolean(),
+                    failed_avp := false,
+                    rfc := 3588 | 6733,
+                    ordered_encode := false,
+                    incoming_maxlen := diameter:message_length()},
+         shutdown = false :: boolean()}).
 
 %% ---------------------------------------------------------------------------
 %% start/2
@@ -85,12 +88,12 @@
 %% reason.
 %% ---------------------------------------------------------------------------
 
--spec start(Type, {RecvData, [Opt], SvcOpts, #diameter_service{}})
+-spec start(Type, {[Opt], SvcOpts, RecvData, #diameter_service{}})
    -> {reference(), pid()}
  when Type :: {connect|accept, diameter:transport_ref()},
-      RecvData :: term(),
       Opt :: diameter:transport_opt(),
-      SvcOpts :: [diameter:service_opt()].
+      SvcOpts :: map(),
+      RecvData :: term().
 
 start({_,_} = Type, T) ->
     Ack = make_ref(),
@@ -117,22 +120,28 @@ init(T) ->
     proc_lib:init_ack({ok, self()}),
     gen_server:enter_loop(?MODULE, [], i(T)).
 
-i({Ack, T, Pid, {RecvData,
-                 Opts,
-                 SvcOpts,
+i({Ack, T, Pid, {Opts,
+                 #{restrict_connections := Restrict}
+                 = SvcOpts0,
+                 RecvData,
                  #diameter_service{applications = Apps,
                                    capabilities = Caps}
                  = Svc}}) ->
     monitor(process, Pid),
     wait(Ack, Pid),
+
+    Dict0 = common_dictionary(Apps),
+    SvcOpts = SvcOpts0#{rfc => rfc(Dict0)},
     putr(restart, {T, Opts, Svc, SvcOpts}),  %% save seeing it in trace
     putr(dwr, dwr(Caps)),                    %%
-    {_,_} = Mask = proplists:get_value(sequence, SvcOpts),
-    Restrict = proplists:get_value(restrict_connections, SvcOpts),
     Nodes = restrict_nodes(Restrict),
-    Dict0 = common_dictionary(Apps),
-    diameter_codec:setopts([{common_dictionary, Dict0},
-                            {string_decode, false}]),
+    CodecKeys = [string_decode,
+                 strict_mbit,
+                 incoming_maxlen,
+                 spawn_opt,
+                 rfc,
+                 ordered_encode],
+
     #watchdog{parent = Pid,
               transport = start(T, Opts, SvcOpts, Nodes, Dict0, Svc),
               tw = proplists:get_value(watchdog_timer,
@@ -140,9 +149,14 @@ i({Ack, T, Pid, {RecvData,
                                        ?DEFAULT_TW_INIT),
               receive_data = RecvData,
               dictionary = Dict0,
-              sequence = Mask,
-              restrict = {Restrict, lists:member(node(), Nodes)},
-              config = config(Opts)}.
+              config =
+                  maps:without(CodecKeys,
+                               config(SvcOpts#{restrict => restrict(Nodes),
+                                               suspect => 1,
+                                               okay => 3},
+                                      Opts)),
+              codec = maps:with(CodecKeys, SvcOpts#{string_decode := false,
+                                                    ordered_encode => false})}.
 
 wait(Ref, Pid) ->
     receive
@@ -152,22 +166,31 @@ wait(Ref, Pid) ->
             exit({shutdown, D})
     end.
 
-%% config/1
+%% Regard anything but the generated RFC 3588 dictionary as modern.
+%% This affects the interpretation of defaults during the decode
+%% of values of type DiameterURI, this having changed from RFC 3588.
+%% (So much for backwards compatibility.)
+rfc(?BASE) ->
+    3588;
+rfc(_) ->
+    6733.
+
+%% config/2
 %%
 %% Could also configure counts for SUSPECT to DOWN and REOPEN to DOWN,
 %% but don't.
 
-config(Opts) ->
+config(Map, Opts) ->
     Config = proplists:get_value(watchdog_config, Opts, []),
-    lists:foldl(fun config/2, #config{}, Config).
+    lists:foldl(fun cfg/2, Map, Config).
 
-config({suspect, N}, Rec)
+cfg({suspect, N}, Map)
   when ?IS_NATURAL(N) ->
-    Rec#config{suspect = N};
+    Map#{suspect := N};
 
-config({okay, N}, Rec)
+cfg({okay, N}, Map)
   when ?IS_NATURAL(N) ->
-    Rec#config{okay = N}.
+    Map#{okay := N}.
 
 %% start/6
 
@@ -377,8 +400,8 @@ transition({accepted = T, TPid}, #watchdog{transport = TPid,
 transition({open, TPid, Hosts, _} = Open,
            #watchdog{transport = TPid,
                      status = initial,
-                     restrict = {_,R},
-                     config = #config{suspect = OS}}
+                     config = #{restrict := R,
+                                suspect := OS}}
            = S) ->
     case okay(role(), Hosts, R) of
         okay ->
@@ -396,8 +419,8 @@ transition({open, TPid, Hosts, _} = Open,
 transition({open = Key, TPid, _Hosts, T},
            #watchdog{transport = TPid,
                      status = down,
-                     config = #config{suspect = OS,
-                                      okay = RO}}
+                     config = #{suspect := OS,
+                                okay := RO}}
            = S) ->
     case RO of
         0 ->  %% non-standard: skip REOPEN
@@ -430,7 +453,7 @@ transition({'DOWN', _, process, TPid, _Reason},
 transition({'DOWN', _, process, TPid, _Reason} = D,
            #watchdog{transport = TPid,
                      status = T,
-                     restrict = {_,R}}
+                     config = #{restrict := R}}
            = S0) ->
     S = S0#watchdog{pending = false,
                     transport = undefined},
@@ -486,9 +509,9 @@ getr(Key) ->
 eraser(Key) ->
     erase({?MODULE, Key}).
 
-%% encode/3
+%% encode/4
 
-encode(dwr = M, Dict0, Mask) ->
+encode(dwr = M, Dict0, Opts, Mask) ->
     Msg = getr(M),
     Seq = diameter_session:sequence(Mask),
     Hdr = #diameter_header{version = ?DIAMETER_VERSION,
@@ -496,10 +519,10 @@ encode(dwr = M, Dict0, Mask) ->
                            hop_by_hop_id = Seq},
     Pkt = #diameter_packet{header = Hdr,
                            msg = Msg},
-    diameter_codec:encode(Dict0, Pkt);
+    diameter_codec:encode(Dict0, Opts, Pkt);
 
-encode(dwa, Dict0, #diameter_packet{header = H, transport_data = TD}
-                   = ReqPkt) ->
+encode(dwa, Dict0, Opts, #diameter_packet{header = H, transport_data = TD}
+                         = ReqPkt) ->
     AnsPkt = #diameter_packet{header
                               = H#diameter_header{is_request = false,
                                                   is_error = undefined,
@@ -507,7 +530,7 @@ encode(dwa, Dict0, #diameter_packet{header = H, transport_data = TD}
                               msg = dwa(ReqPkt),
                               transport_data = TD},
 
-    diameter_codec:encode(Dict0, AnsPkt).
+    diameter_codec:encode(Dict0, Opts, AnsPkt).
 
 %% okay/3
 
@@ -577,9 +600,10 @@ tw({M,F,A}) ->
 send_watchdog(#watchdog{pending = false,
                         transport = TPid,
                         dictionary = Dict0,
-                        sequence = Mask}
+                        config = #{sequence := Mask},
+                        codec = Opts}
               = S) ->
-    #diameter_packet{bin = Bin} = EPkt = encode(dwr, Dict0, Mask),
+    #diameter_packet{bin = Bin} = EPkt = encode(dwr, Dict0, Opts, Mask),
     diameter_traffic:incr(send, EPkt, TPid, Dict0),
     send(TPid, {send, Bin}),
     ?LOG(send, 'DWR'),
@@ -601,17 +625,18 @@ incoming(Route, Name, Pkt, S) ->
 %% rcv/3
 
 rcv('DWR', Pkt, #watchdog{transport = TPid,
-                          dictionary = Dict0}
+                          dictionary = Dict0,
+                          codec = Opts}
                 = S) ->
     ?LOG(recv, 'DWR'),
-    DPkt = diameter_codec:decode(Dict0, Pkt),
+    DPkt = diameter_codec:decode(Dict0, Opts, Pkt),
     diameter_traffic:incr(recv, DPkt, TPid, Dict0),
     diameter_traffic:incr_error(recv, DPkt, TPid, Dict0),
     #diameter_packet{header = H,
                      transport_data = T,
                      bin = Bin}
         = EPkt
-        = encode(dwa, Dict0, Pkt),
+        = encode(dwa, Dict0, Opts, Pkt),
     diameter_traffic:incr(send, EPkt, TPid, Dict0),
     diameter_traffic:incr_rc(send, EPkt, TPid, Dict0),
 
@@ -623,12 +648,13 @@ rcv('DWR', Pkt, #watchdog{transport = TPid,
     throw(S);
 
 rcv('DWA', Pkt, #watchdog{transport = TPid,
-                          dictionary = Dict0}
+                          dictionary = Dict0,
+                          codec = Opts}
                 = S) ->
     ?LOG(recv, 'DWA'),
     diameter_traffic:incr(recv, Pkt, TPid, Dict0),
     diameter_traffic:incr_rc(recv,
-                             diameter_codec:decode(Dict0, Pkt),
+                             diameter_codec:decode(Dict0, Opts, Pkt),
                              TPid,
                              Dict0),
     throw(S);
@@ -690,12 +716,12 @@ rcv(_, #watchdog{status = okay} = S) ->
 %%   SUSPECT       Receive non-DWA      Failback()
 %%                                      SetWatchdog()        OKAY
 
-rcv('DWA', #watchdog{status = suspect, config = #config{suspect = OS}} = S) ->
+rcv('DWA', #watchdog{status = suspect, config = #{suspect := OS}} = S) ->
     set_watchdog(S#watchdog{status = okay,
                             num_dwa = OS,
                             pending = false});
 
-rcv(_, #watchdog{status = suspect, config = #config{suspect = OS}} = S) ->
+rcv(_, #watchdog{status = suspect, config = #{suspect := OS}} = S) ->
     set_watchdog(S#watchdog{status = okay,
                             num_dwa = OS});
 
@@ -705,8 +731,8 @@ rcv(_, #watchdog{status = suspect, config = #config{suspect = OS}} = S) ->
 
 rcv('DWA', #watchdog{status = reopen,
                      num_dwa = N,
-                     config = #config{suspect = OS,
-                                      okay = RO}}
+                     config = #{suspect := OS,
+                                okay := RO}}
            = S)
   when N+1 == RO ->
     S#watchdog{status = okay,
@@ -837,18 +863,19 @@ restart(S) ->  %% reconnect has won race with timeout
 
 restart({{connect, _} = T, Opts, Svc, SvcOpts},
         #watchdog{parent = Pid,
-                  restrict = {R,_},
+                  config = #{restrict_connections := R}
+                         = M,
                   dictionary = Dict0}
         = S) ->
     send(Pid, {reconnect, self()}),
     Nodes = restrict_nodes(R),
     S#watchdog{transport = start(T, Opts, SvcOpts, Nodes, Dict0, Svc),
-               restrict = {R, lists:member(node(), Nodes)}};
+               config = M#{restrict => restrict(Nodes)}};
 
 %% No restriction on the number of connections to the same peer: just
 %% die. Note that a state machine never enters state REOPEN in this
 %% case.
-restart({{accept, _}, _, _, _}, #watchdog{restrict = {_, false}}) ->
+restart({{accept, _}, _, _, _}, #watchdog{config = #{restrict := false}}) ->
     stop;
 
 %% Otherwise hang around until told to die, either by the service or
@@ -892,3 +919,8 @@ restrict_nodes(Nodes)
 
 restrict_nodes(F) ->
     diameter_lib:eval(F).
+
+%% restrict/1
+
+restrict(Nodes) ->
+    lists:member(node(), Nodes).
diff --git a/lib/diameter/src/compiler/diameter_codegen.erl b/lib/diameter/src/compiler/diameter_codegen.erl
index 928ae37e7f..f56e4a5249 100644
--- a/lib/diameter/src/compiler/diameter_codegen.erl
+++ b/lib/diameter/src/compiler/diameter_codegen.erl
@@ -150,20 +150,21 @@ erl_forms(Mod, ParseD) ->
                                     {id, 0},
                                     {vendor_id, 0},
                                     {vendor_name, 0},
-                                    {decode_avps, 2}, %% in diameter_gen.hrl
-                                    {encode_avps, 2}, %%
+                                    {decode_avps, 3}, %% in diameter_gen.hrl
+                                    {encode_avps, 3}, %%
+                                    {grouped_avp, 4}, %%
                                     {msg_name, 2},
                                     {msg_header, 1},
                                     {rec2msg, 1},
                                     {msg2rec, 1},
                                     {name2rec, 1},
                                     {avp_name, 2},
+                                    {avp_arity, 1},
                                     {avp_arity, 2},
                                     {avp_header, 1},
-                                    {avp, 3},
-                                    {grouped_avp, 3},
+                                    {avp, 4},
                                     {enumerated_avp, 3},
-                                    {empty_value, 1},
+                                    {empty_value, 2},
                                     {dict, 0}]},
               %% diameter.hrl is included for #diameter_avp
               {?attribute, include_lib, "diameter/include/diameter.hrl"},
@@ -178,7 +179,8 @@ erl_forms(Mod, ParseD) ->
               f_msg2rec(ParseD),
               f_name2rec(ParseD),
               f_avp_name(ParseD),
-              f_avp_arity(ParseD),
+              f_avp_arity_1(ParseD),
+              f_avp_arity_2(ParseD),
               f_avp_header(ParseD),
               f_avp(ParseD),
               f_enumerated_avp(ParseD),
@@ -418,10 +420,32 @@ vendor_id_map(ParseD) ->
                          get_value(grouped, ParseD)).
 
 %%% ------------------------------------------------------------------------
+%%% # avp_arity/1
+%%% ------------------------------------------------------------------------
+
+f_avp_arity_1(ParseD) ->
+    {?function, avp_arity, 1, avp_arities(ParseD) ++ [?BADARG(1)]}.
+
+avp_arities(ParseD) ->
+    Msgs = get_value(messages, ParseD),
+    Groups = get_value(grouped, ParseD)
+          ++ lists:flatmap(fun avps/1, get_value(import_groups, ParseD)),
+    lists:map(fun c_avp_arities/1, Msgs ++ Groups).
+
+c_avp_arities({N,_,_,_,As}) ->
+    c_avp_arities(N,As);
+c_avp_arities({N,_,_,As}) ->
+    c_avp_arities(N,As).
+
+c_avp_arities(Name, Avps) ->
+    Arities = [{?A(N), A} || T <- Avps, {N,A} <- [avp_info(T)]],
+    {?clause, [?Atom(Name)], [], [?TERM(Arities)]}.
+
+%%% ------------------------------------------------------------------------
 %%% # avp_arity/2
 %%% ------------------------------------------------------------------------
 
-f_avp_arity(ParseD) ->
+f_avp_arity_2(ParseD) ->
     {?function, avp_arity, 2, avp_arity(ParseD)}.
 
 avp_arity(ParseD) ->
@@ -452,7 +476,7 @@ c_arity(Name, Avp) ->
 %%% ------------------------------------------------------------------------
 
 f_avp(ParseD) ->
-    {?function, avp, 3, avp(ParseD) ++ [?BADARG(3)]}.
+    {?function, avp, 4, avp(ParseD) ++ [?BADARG(4)]}.
 
 avp(ParseD) ->
     Native     = get_value(avp_types, ParseD),
@@ -491,19 +515,25 @@ avp(Native, Imported, Custom, Enums) ->
 not_in(List, X) ->
     not lists:member(X, List).
 
-c_base_avp({AvpName, T}) ->
-    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName)],
+c_base_avp({AvpName, "Enumerated"}) ->
+    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName), ?VAR('_')],
      [],
-     [b_base_avp(AvpName, T)]}.
+     [?CALL(enumerated_avp, [?VAR('T'), ?Atom(AvpName), ?VAR('Data')])]};
 
-b_base_avp(AvpName, "Enumerated") ->
-    ?CALL(enumerated_avp, [?VAR('T'), ?Atom(AvpName), ?VAR('Data')]);
-
-b_base_avp(AvpName, "Grouped") ->
-    ?CALL(grouped_avp, [?VAR('T'), ?Atom(AvpName), ?VAR('Data')]);
+c_base_avp({AvpName, "Grouped"}) ->
+    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName), ?VAR('Opts')],
+     [],
+     [?CALL(grouped_avp, [?VAR('T'),
+                          ?Atom(AvpName),
+                          ?VAR('Data'),
+                          ?VAR('Opts')])]};
 
-b_base_avp(_, Type) ->
-    ?APPLY(diameter_types, ?A(Type), [?VAR('T'), ?VAR('Data')]).
+c_base_avp({AvpName, Type}) ->
+    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName), ?VAR('Opts')],
+     [],
+     [?APPLY(diameter_types, ?A(Type), [?VAR('T'),
+                                        ?VAR('Data'),
+                                        ?VAR('Opts')])]}.
 
 cs_imported_avp({Mod, Avps}, Enums, CustomNames) ->
     lists:map(fun(A) -> imported_avp(Mod, A, Enums) end,
@@ -525,11 +555,13 @@ imported_avp(Mod, {AvpName, _, _, _}, _) ->
     c_imported_avp(Mod, AvpName).
 
 c_imported_avp(Mod, AvpName) ->
-    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName)],
+    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName), ?VAR('Opts')],
      [],
-     [?APPLY(Mod, avp, [?VAR('T'),
-                        ?VAR('Data'),
-                        ?Atom(AvpName)])]}.
+     [?CALL(avp, [?VAR('T'),
+                  ?VAR('Data'),
+                  ?Atom(AvpName),
+                  ?VAR('Opts'),
+                  ?ATOM(Mod)])]}.
 
 cs_custom_avp({Mod, Key, Avps}, Dict) ->
     lists:map(fun(N) -> c_custom_avp(Mod, Key, N, orddict:fetch(N, Dict)) end,
@@ -537,9 +569,12 @@ cs_custom_avp({Mod, Key, Avps}, Dict) ->
 
 c_custom_avp(Mod, Key, AvpName, Type) ->
     {F,A} = custom(Key, AvpName, Type),
-    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName)],
+    {?clause, [?VAR('T'), ?VAR('Data'), ?Atom(AvpName), ?VAR('Opts')],
      [],
-     [?APPLY(?A(Mod), ?A(F), [?VAR('T'), ?Atom(A), ?VAR('Data')])]}.
+     [?APPLY(?A(Mod), ?A(F), [?VAR('T'),
+                              ?Atom(A),
+                              ?VAR('Data'),
+                              ?VAR('Opts')])]}.
 
 custom(custom_types, AvpName, Type) ->
     {AvpName, Type};
@@ -568,7 +603,11 @@ enumerated_avp(Mod, Es, Enums) ->
                   Es).
 
 cs_enumerated_avp(true, Mod, Name) ->
-    [c_imported_avp(Mod, Name)];
+    [{?clause, [?VAR('T'), ?Atom(Name), ?VAR('Data')],
+     [],
+     [?APPLY(Mod, enumerated_avp, [?VAR('T'),
+                                   ?Atom(Name),
+                                   ?VAR('Data')])]}];
 cs_enumerated_avp(false, _, _) ->
     [].
 
@@ -682,7 +721,7 @@ v(false, _, _, _) ->
 %%% ------------------------------------------------------------------------
 
 f_empty_value(ParseD) ->
-    {?function, empty_value, 1, empty_value(ParseD)}.
+    {?function, empty_value, 2, empty_value(ParseD)}.
 
 empty_value(ParseD) ->
     Imported = lists:flatmap(fun avps/1, get_value(import_enums, ParseD)),
@@ -692,15 +731,17 @@ empty_value(ParseD) ->
                   not lists:keymember(N, 1, Imported)]
         ++ Imported,
     lists:map(fun c_empty_value/1, Groups ++ Enums)
-        ++ [{?clause, [?VAR('Name')], [], [?CALL(empty, [?VAR('Name')])]}].
+        ++ [{?clause, [?VAR('Name'), ?VAR('Opts')],
+             [],
+             [?CALL(empty, [?VAR('Name'), ?VAR('Opts')])]}].
 
 c_empty_value({Name, _, _, _}) ->
-    {?clause, [?Atom(Name)],
+    {?clause, [?Atom(Name), ?VAR('Opts')],
      [],
-     [?CALL(empty_group, [?Atom(Name)])]};
+     [?CALL(empty_group, [?Atom(Name), ?VAR('Opts')])]};
 
 c_empty_value({Name, _}) ->
-    {?clause, [?Atom(Name)],
+    {?clause, [?Atom(Name), ?VAR('_')],
      [],
      [?TERM(<<0:32>>)]}.
 
diff --git a/lib/diameter/src/diameter.app.src b/lib/diameter/src/diameter.app.src
index d380ebbd92..9a6e47006b 100644
--- a/lib/diameter/src/diameter.app.src
+++ b/lib/diameter/src/diameter.app.src
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2016. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -28,10 +28,10 @@
       ]},
   {registered, [%REGISTERED%]},
   {applications, [
-      {stdlib, "2.0"}, {kernel, "3.0"}%, {erts, "6.0"}
-      %% {syntax-tools, "1.6.14"}
-      %% {runtime-tools, "1.8.14"}
-      %, {ssl, "5.3.4"}
+      {stdlib, "2.4"}, {kernel, "3.2"}%, {erts, "6.4"}
+      %% {syntax-tools, "1.6,18"}
+      %% {runtime-tools, "1.8.16"}
+      %, {ssl, "6.0"}
       ]},
   {env, []},
   {mod, {diameter_app, []}},
diff --git a/lib/diameter/src/modules.mk b/lib/diameter/src/modules.mk
index 4e4ce60ddf..bb3b234d20 100644
--- a/lib/diameter/src/modules.mk
+++ b/lib/diameter/src/modules.mk
@@ -1,7 +1,7 @@
 
 # %CopyrightBegin%
 #
-# Copyright Ericsson AB 2010-2016. All Rights Reserved.
+# Copyright Ericsson AB 2010-2017. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -39,7 +39,7 @@ RT_MODULES = \
 	base/diameter_config \
 	base/diameter_config_sup \
 	base/diameter_codec \
-	base/diameter_dict \
+	base/diameter_gen \
 	base/diameter_lib \
 	base/diameter_misc_sup \
 	base/diameter_peer \