raw option doesn't work gen_tcp when the socket backend is enabled (otp 24)

[dogtapdsd]

Describe the bug
https://bugs.erlang.org/browse/ERL-1287
this bug was fixed in otp 23.1, but happen again in otp 24, It cann't listening multiple sockets on the same port.

To Reproduce

Eshell V12.0.3 (abort with ^G)
1>
1> gen_tcp:listen(0, [{inet_backend, socket}, {raw, 1, 15, <<1:32/native>>}, {port, 8888}, {ip, any}]).
{ok,{'$inet',gen_tcp_socket,
{<0.82.0>,
{'$socket',#Ref<0.1220593668.1297743873.200397>}}}}
2>
2> gen_tcp:listen(0, [{inet_backend, socket}, {raw, 1, 15, <<1:32/native>>}, {port, 8888}, {ip, any}]).
{error,eaddrinuse}

Expected behavior
I test in otp 23.3 with no error

Eshell V11.2 (abort with ^G)
1> gen_tcp:listen(0, [{inet_backend, socket}, {raw, 1, 15, <<1:32/native>>}, {port, 8888}, {ip, any}]).
{ok,{'$inet',gen_tcp_socket,
{<0.83.0>,
{'$socket',#Ref<0.3300202661.3446013953.155967>}}}}
2>
2> gen_tcp:listen(0, [{inet_backend, socket}, {raw, 1, 15, <<1:32/native>>}, {port, 8888}, {ip, any}]).
{ok,{'$inet',gen_tcp_socket,
{<0.85.0>,
{'$socket',#Ref<0.3300202661.3446013953.155982>}}}}
3>

Affected versions
Erlang/OTP 24 [erts-12.0.3]

[RaimoNiskanen]

It seems that I refactored code when implementing fdopen/2 in gen_tcp_socket, and then setting level socket options was moved to after the bind(2) call. Now I will have to figure out if that was purely accidental or if there was some reason behind it.

That code refactoring causes your raw option (that by the way exists in non-raw form too {reuseaddr, true}), to be set after the address has been bound. Hence it has no effect. The same applies to the non-raw option too... So this is formally not the same bug that was fixed in ERL-1287.
Edit: your raw option is SO_REUSEPORT, not SO_REUSEADDR. My mistake.

I want to take a more thorough look at option handling in gen_tcp_socket, to see how to make it less messy...

[RaimoNiskanen]

This should be the smallest possible and probably correct fix:

diff --git a/lib/kernel/src/gen_tcp_socket.erl b/lib/kernel/src/gen_tcp_socket.erl
index 1841623241..5125bc4997 100644
--- a/lib/kernel/src/gen_tcp_socket.erl
+++ b/lib/kernel/src/gen_tcp_socket.erl
@@ -316,8 +316,8 @@ listen_open(Domain, ListenOpts, Opts, ExtraOpts, Backlog, BindAddr) ->
                   [{start_opts, StartOpts}] ++ SocketOpts ++ Setopts_1),
             ErrRef = make_ref(),
             try
-                ok(ErrRef, call_bind(Server, default_any(Domain, BindAddr))),
                 ok(ErrRef, call(Server, {setopts, Setopts})),
+                ok(ErrRef, call_bind(Server, default_any(Domain, BindAddr))),
                 Socket = val(ErrRef, call(Server, {listen, Backlog})),
                 {ok, ?MODULE_socket(Server, Socket)}
             catch

[dogtapdsd]

thanks for your reply，I will check those fix codes。

[RaimoNiskanen]

Fix merged

[hazardfn]

I believe these symptoms have reappeared in OTP 26 (at least broken on 26.1.2). See: ninenines/ranch#216 (comment)