Hi.

I have a following configuration for the outgoing connection [XXX-1] client = yes accept = 127.0.0.1:1564 connect = some-server:9999 local = some-other-address

Sometimes, or rather, quite regular, the connection to localhost port 1564 results in immediate connection close and logging the following: May 30 23:06:58 tom stunnel: LOG5[4]: Service [XXX-1] accepted connection from 127.0.0.1:12848 May 30 23:06:58 tom stunnel: LOG3[4]: local_bind (ephemeral port): Invalid argument (22)

I traced the syscalls and see the following: 28196 stunnel CALL socket(PF_INET6,SOCK_STREAM,IPPROTO_IP) 28196 stunnel RET socket 10/0xa 28196 stunnel CALL fcntl(0xa,F_GETFL,0) 28196 stunnel RET fcntl 2 28196 stunnel CALL fcntl(0xa,F_SETFL,0x6<O_RDWR|O_NONBLOCK>) 28196 stunnel RET fcntl 0 28196 stunnel CALL fcntl(0xa,F_SETFD,FD_CLOEXEC) 28196 stunnel RET fcntl 0 28196 stunnel CALL bind(0xa,0x802808a6c,0x10) 28196 stunnel STRU struct sockaddr { AF_INET, 176.36.249.139:0 } 28196 stunnel RET bind -1 errno 22 Invalid argument

The socket was created with INET6 address family, but bind was done for INET AF. Indeed, both some-server and some-other-address have both A and AAAA records, corresponding addresses are configured and functional. OS is FreeBSD, I was ensured that this combination (INET6 socket and INET bind) is not correct.

It probably works sometime when first resolved addresses for names happen to come from the same address family, but when resolvers return different order, the situation above occurs. Disabling ipv6 support makes the connection work reliably, which confirms my observations.

I am using stunnel 5.31.

Would be nice to have this fixed. Thanks.