async_req: fix non-blocking connect()
According to Stevens UNIX Network Programming and various other sources,
the correct handling for non-blocking connect() is:
- when the initial connect() return -1/EINPROGRESS polling the socket
for *writeability*
- in the poll handler call getsocktopt() with SO_ERROR to get the
finished connect() return value
Simply calling connect() a second time without error checking is
probably wrong and not portable. For a successfull connect() Linux
returns 0, but Solaris will return EISCONN:
24254: 0.0336 0.0002 connect(4, 0xFEFFECAC, 16, SOV_DEFAULT) Err#150 EINPROGRESS
24254: AF_INET name = 10.10.10.143 port = 1024
24254: 0.0349 0.0001 port_associate(3, 4, 0x00000004, 0x0000001D,0x080648A8) = 0
24254: 0.0495 0.0146 port_getn(3, 0xFEFFEB50, 1, 1, 0xFEFFEB60) = 1 [0]
24254: 0.0497 0.0002 connect(4, 0x080646E4, 16, SOV_DEFAULT) Err#133 EISCONN
24254: AF_INET name = 10.10.10.143 port = 1024
Bug: https://bugzilla.samba.org/show_bug.cgi?id=11564
Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>