Merge branch 'anders/diameter/strict_capx/OTP-14546' into maint

* anders/diameter/strict_capx/OTP-14546:
  Document transport_opt() strict_capx
  Rename transport_opt() capx_strictness to strict_capx

4 files changed, 19 insertions, 3 deletions

diff --git a/lib/diameter/doc/src/diameter.xml b/lib/diameter/doc/src/diameter.xml
index ad82cafd2f..8b72736108 100644
--- a/lib/diameter/doc/src/diameter.xml
+++ b/lib/diameter/doc/src/diameter.xml
@@ -1411,6 +1411,20 @@ Defaults to the list configured on the service if not specified.</p>
 </item>
 
 <tag>
+<marker id="strict_capx"/><c>{strict_capx, boolean()]}</c></tag>
+<item>
+<p>
+Whether or not to enforce the RFC 6733 requirement that any message
+before capabilities exchange should close the peer connection.
+If false then unexpected messages are discarded.</p>
+
+<p>
+Defaults to true.
+Changing this results in non-standard behaviour, but can be useful in
+case peers are known to be behave badly.</p>
+</item>
+
+<tag>
 <marker id="transport_config"/><c>{transport_config, term()}</c></tag><item/>
 <tag><c>{transport_config, term(), &dict_Unsigned32; | infinity}</c></tag>
 <item>
diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index 2e18a1d903..888a108f8b 100644
--- a/lib/diameter/src/base/diameter.erl
+++ b/lib/diameter/src/base/diameter.erl
@@ -394,7 +394,7 @@ call(SvcName, App, Message) ->
     | {capabilities, [capability()]}
     | {capabilities_cb, evaluable()}
     | {capx_timeout, 'Unsigned32'()}
-    | {capx_strictness, boolean()}
+    | {strict_capx, boolean()}
     | {disconnect_cb, evaluable()}
     | {dpr_timeout, 'Unsigned32'()}
     | {dpa_timeout, 'Unsigned32'()}
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index f1b6e56782..d54dbd9976 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -591,6 +591,8 @@ opt({K, Tmo})
     ?IS_UINT32(Tmo);
 
 opt({capx_strictness, B}) ->
+    is_boolean(B) andalso {value, {strict_capx, B}};
+opt({strict_capx, B}) ->
     is_boolean(B);
 
 opt({length_errors, T}) ->
diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 1a3438fd22..d99f11a697 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -238,7 +238,7 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) ->
                     proplists:get_value(dpa_timeout, Opts, ?DPA_TIMEOUT)}),
 
     Tmo = proplists:get_value(capx_timeout, Opts, ?CAPX_TIMEOUT),
-    Strictness = proplists:get_value(capx_strictness, Opts, true),
+    Strict = proplists:get_value(strict_capx, Opts, true),
     LengthErr = proplists:get_value(length_errors, Opts, exit),
 
     {TPid, Addrs} = start_transport(T, Rest, Svc),
@@ -252,7 +252,7 @@ i({Ack, WPid, {M, Ref} = T, Opts, {SvcOpts, Nodes, Dict0, Svc}}) ->
            mode = M,
            service = svc(Svc, Addrs),
            length_errors = LengthErr,
-           strict = Strictness,
+           strict = Strict,
            incoming_maxlen = Maxlen,
            codec = maps:with([decode_format,
                               string_decode,