Corinna Vinschen wrote:
On Aug 22 20:32, Christian Franke wrote:
Corinna Vinschen wrote:
Another potential solution might be to defer the AF_UNIX handshake to
the first send/recv:
Whatever the peers do, there is a certain protocol used. That means,
there's an implicit understanding who's going to do the first send and
who's doing the first recv. So, after connect/accept, both sides of the
sockets go into "connected_but_handshake_missing" mode. On the first
send/recv, the handshake gets started and if it fails, send/recv
return ECONNRESET.
Is an actual handshake really required? It would possibly be sufficient that
each peer sends its secret+credential and then expects a correct
secret+credential from the other peer before sending anything.
After actual connect()/accept():
send our secret+cred (should not block due to TCP queuing).
So both peers send their credentials...
if (! nonblocking recv peer secret+cred)
set_state(connected_but_secret_missing)
else
set_state(connected)
This will almost always result in connected_but_secret_missing. It's
probably ok to drop the recv attempt here entirely.
Agree.
Before actual send()/recv()/getpeerid():
if (state == connected_but_secret_missing) {
if (! recv peer secret+cred)
abort_connection(ECONNRESET)
else
set_state(connected)
}
Sounds like a nice idea. We should try that. I'm just not sure how
much time I have left to work on this before my vaca next month. Do you
have fun to look into that? We have waited so long for postfix, I guess
a couple more weeks won't really hurt.
OK, will try that
Postfix apparently pushes Cygwin to its limits. With a test cygwin1.dll
where the secret+cred exchange is fully disabled, postfix starts up but
queuing of mail fails.
This is because fchmod() is called on a file rename()d after open():
fd = open("tempfile", ., 0600);
// use fd's inode number and current time to create unique "queuefile".
rename("tempfile", "queuefile");
write(fd, "SOME MAIL....", .);
fchmod(fd, 0700); // fails with ENOENT on Cygwin (because it does a
chmod("tempfile",.)?)
close(fd);
A workaround using chmod("queuefile", 0700) helped here. Then smtp
client, smtpd server (direct or via smarthost), sendmail emulation and
local delivery to maildir works. Running as service with uid/gid
switching is not tested yet.
It will likely take some time to look into all these details before
first ITP.
(Therefore let's forget the "cygcheck -m" patch for now :-).
Christian
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