Add compat Websocket compression option

doc/src/manual/gun.asciidoc

@@ -573,7 +573,7 @@ detail.
 ----
 ws_opts() :: #{
     closing_timeout  => timeout(),
-    compress         => boolean(),
+    compress         => boolean() | compat,
     default_protocol => module(),
     flow             => pos_integer(),
     invalid_request_headers => raise | ignore,
@@ -599,6 +599,10 @@ compress (false)::
 Whether to enable permessage-deflate compression. This does
 not guarantee that compression will be used as it is the
 server that ultimately decides. Defaults to false.
++
+The value `compat` will enable compression without sending
+any parameter. It should help connecting to servers that
+reject parameters that Gun sends by default.
 
 default_protocol (gun_ws_h)::
 
@@ -645,6 +649,7 @@ By default no user option is defined.
 
 == Changelog
 
+* *2.5*: Websocket `compress` option value `compat` was added.
 * *2.4*: The `max_header_block_size` and `max_trailer_block_size`
          HTTP/1.1 options were added.
 * *2.4*: The `invalid_request_headers` request option was added

doc/src/manual/gun.ws_upgrade.asciidoc

@@ -93,7 +93,7 @@ end.
 [source,erlang]
 ----
 StreamRef = gun:ws_upgrade(ConnPid, "/ws", [], #{
-    compress => false
+    compress => true
 }).
 ----
 

src/gun.erl

@@ -290,7 +290,7 @@
 
 -type ws_opts() :: #{
 	closing_timeout => timeout(),
-	compress => boolean(),
+	compress => boolean() | compat,
 	default_protocol => module(),
 	flow => pos_integer(),
 	invalid_request_headers => raise | ignore,

src/gun_http.erl

@@ -1030,11 +1030,15 @@ ws_upgrade(State=#http_state{version='HTTP/1.0'},
 ws_upgrade(State=#http_state{out=head}, StreamRef, ReplyTo,
 		Host, Port, Path, Headers0, WsOpts, CookieStore0, EvHandler, EvHandlerState0) ->
 	{Headers1, GunExtensions} = case maps:get(compress, WsOpts, false) of
-		true -> {[{<<"sec-websocket-extensions">>,
-				<<"permessage-deflate; client_max_window_bits; server_max_window_bits=15">>}
-			|Headers0],
-			[<<"permessage-deflate">>]};
-		false -> {Headers0, []}
+		true ->
+			{[{<<"sec-websocket-extensions">>,
+				<<"permessage-deflate; client_max_window_bits">>}
+			|Headers0], [<<"permessage-deflate">>]};
+		compat ->
+			{[{<<"sec-websocket-extensions">>, <<"permessage-deflate">>}
+			|Headers0], [<<"permessage-deflate">>]};
+		false ->
+			{Headers0, []}
 	end,
 	Headers2 = case maps:get(protocols, WsOpts, []) of
 		[] -> Headers1;

src/gun_http2.erl

@@ -1591,7 +1591,10 @@ ws_upgrade1(State=#http2_state{socket=Socket, transport=Transport,
 	{Headers2, GunExtensions} = case maps:get(compress, WsOpts, false) of
 		true ->
 			{[{<<"sec-websocket-extensions">>,
-				<<"permessage-deflate; client_max_window_bits; server_max_window_bits=15">>}
+				<<"permessage-deflate; client_max_window_bits">>}
+			|Headers1], [<<"permessage-deflate">>]};
+		compat ->
+			{[{<<"sec-websocket-extensions">>, <<"permessage-deflate">>}
 			|Headers1], [<<"permessage-deflate">>]};
 		false ->
 			{Headers1, []}

src/gun_ws.erl

@@ -70,6 +70,8 @@ do_check_options([{closing_timeout, T}|Opts]) when is_integer(T), T > 0 ->
 	do_check_options(Opts);
 do_check_options([{compress, B}|Opts]) when is_boolean(B) ->
 	do_check_options(Opts);
+do_check_options([{compress, compat}|Opts]) ->
+	do_check_options(Opts);
 do_check_options([{default_protocol, M}|Opts]) when is_atom(M) ->
 	do_check_options(Opts);
 do_check_options([{flow, InitialFlow}|Opts]) when is_integer(InitialFlow), InitialFlow > 0 ->