Let messages and grouped AVPs be decoded to lists

That is, decode to the same format that encode already accepts. Only a
message has its name at the head of the list since AVPs are already
name/value pairs.

7 files changed, 38 insertions, 18 deletions

diff --git a/lib/diameter/doc/src/diameter.xml b/lib/diameter/doc/src/diameter.xml
index bfb6da41b5..e525ab3345 100644
--- a/lib/diameter/doc/src/diameter.xml
+++ b/lib/diameter/doc/src/diameter.xml
@@ -970,7 +970,8 @@ occur in the message in question.</p>
 </item>
 
 <tag>
-<marker id="record_decode"/><c>{record_decode, boolean() | map}</c></tag>
+<marker id="record_decode"/>
+<c>{record_decode, boolean() | list | map}</c></tag>
 <item>
 <p>
 Whether or not to decode message and grouped AVPs to records in the
diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index 4269c84cd2..b033632c47 100644
--- a/lib/diameter/src/base/diameter.erl
+++ b/lib/diameter/src/base/diameter.erl
@@ -338,7 +338,7 @@ call(SvcName, App, Message) ->
     | {restrict_connections, restriction()}
     | {sequence, sequence() | evaluable()}
     | {share_peers, remotes()}
-    | {record_decode, boolean() | map}
+    | {record_decode, boolean() | list | map}
     | {string_decode, boolean()}
     | {strict_mbit, boolean()}
     | {incoming_maxlen, message_length()}
diff --git a/lib/diameter/src/base/diameter_codec.erl b/lib/diameter/src/base/diameter_codec.erl
index 0c43d52093..9043af145e 100644
--- a/lib/diameter/src/base/diameter_codec.erl
+++ b/lib/diameter/src/base/diameter_codec.erl
@@ -379,10 +379,16 @@ decode_avps(MsgName, Mod, AppMod, Opts, Pkt, Avps) ->  %% ... or not
                                         Opts#{dictionary => AppMod,
                                               failed_avp => false}),
     ?LOGC([] /= Errors, decode_errors, Pkt#diameter_packet.header),
-    Pkt#diameter_packet{msg = Rec,
+    Pkt#diameter_packet{msg = reformat(MsgName, Rec, Opts),
                         errors = Errors,
                         avps = As}.
 
+reformat(MsgName, Avps, #{decode_format := list}) ->
+    [MsgName | Avps];
+
+reformat(_, Msg, _) ->
+    Msg.
+
 %%% ---------------------------------------------------------------------------
 %%% # decode_header/1
 %%% ---------------------------------------------------------------------------
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index a790b946c1..8f958a67b4 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -769,7 +769,9 @@ opt(K, true = B)
        K == string_decode ->
     B;
 
-opt(record_decode, map = T) ->
+opt(record_decode, T)
+  when T == list;
+       T == map ->
     T;
 
 opt(restrict_connections, T)
diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl
index be2e221b7e..2381b73d07 100644
--- a/lib/diameter/src/base/diameter_gen.erl
+++ b/lib/diameter/src/base/diameter_gen.erl
@@ -178,14 +178,17 @@ enc_AVP(_Name, {_Dict, _AvpName, _Data} = T, Opts, _) ->
    -> {parent_record(), [avp()], Failed}
  when Failed :: [{5000..5999, #diameter_avp{}}].
 
-decode_avps(Name, Recs, #{module := Mod} = Opts) ->
+decode_avps(Name, Recs, #{module := Mod, record_decode := Fmt} = Opts) ->
     {Avps, {Rec, AM, Failed}}
         = mapfoldl(fun(T,A) -> decode(Name, Opts, Mod, T, A) end,
-                   {newrec(Mod, Name, Opts), #{}, []},
+                   {newrec(Mod, Name, Fmt), #{}, []},
                    Recs),
     %% AM counts the number of top-level AVPs, which missing/4 then
     %% uses when adding 5005 errors.
-    {Rec, Avps, Failed ++ missing(Name, Opts, Mod, AM)}.
+    Arities = Mod:avp_arity(Name),
+    {reformat(Rec, Arities, Fmt),
+     Avps,
+     Failed ++ missing(Arities, Opts, Mod, AM)}.
 
 %% Append 5005 errors so that errors are reported in the order
 %% encountered. Failed-AVP should typically contain the first
@@ -216,10 +219,10 @@ mapfoldl(_, Acc, [], List) ->
 %%      Vendor-Id if applicable.  The value field of the missing AVP
 %%      should be of correct minimum length and contain zeros.
 
-missing(Name, Opts, Mod, AM) ->
+missing(Arities, Opts, Mod, AM) ->
     lists:foldl(fun(T,A) -> missing(T, AM, Opts, Mod, A) end,
                 [],
-                Mod:avp_arity(Name)).
+                Arities).
 
 %% missing/5
 
@@ -631,7 +634,7 @@ too_many(FieldName, M, Map) ->
 
 %% set/5
 
-set(_, _, _, _, undefined = No) ->
+set(_, _, _, _, false = No) ->
     No;
 
 set(1, F, Value, _, Map)
@@ -743,20 +746,28 @@ empty(Name, #{module := Mod} = Opts) ->
 
 %% newrec/3
 
-newrec(_, _, #{record_decode := false}) ->
-    undefined;
+newrec(_, _, false = No) ->
+    No;
 
-newrec(_, Name, #{record_decode := map}) ->
-    #{':name' => Name};
+newrec(Mod, Name, true) ->
+    newrec(Mod, Name);
 
-newrec(Mod, Name, _) ->
-    newrec(Mod, Name).
+newrec(_, Name, _) ->
+    #{':name' => Name}.
 
 %% newrec/2
 
 newrec(Mod, Name) ->
     Mod:'#new-'(Mod:name2rec(Name)).
 
+%% reformat/3
+
+reformat(Map, Arities, list) ->
+    [{F,V} || {F,_} <- Arities, #{F := V} <- [Map]];
+
+reformat(Rec, _, _) ->
+    Rec.
+
 %% def/1
 
 def(1) ->
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 3e555f6263..7f7e3e3a3f 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -113,7 +113,7 @@
                       restrict_connections := diameter:restriction(),
                       incoming_maxlen := diameter:message_length(),
                       strict_mbit := boolean(),
-                      record_decode := boolean() | map,
+                      record_decode := boolean() | map | list,
                       string_decode := boolean(),
                       spawn_opt := list() | {module(), atom(), list()}}}).
 
diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl
index f7dec2441f..6594994cfa 100644
--- a/lib/diameter/src/base/diameter_traffic.erl
+++ b/lib/diameter/src/base/diameter_traffic.erl
@@ -76,7 +76,7 @@
          service_name :: diameter:service_name(),
          apps         :: [#diameter_app{}],
          sequence     :: diameter:sequence(),
-         codec        :: #{record_decode := boolean() | map,
+         codec        :: #{record_decode := boolean() | map | list,
                            string_decode := boolean(),
                            strict_mbit := boolean(),
                            incoming_maxlen := diameter:message_length()}}).