esr@mrst.UUCP (Eric S. Rose) (07/14/87)
Hello there....
Can anyone help me with a problem involving sockets?
I have a simple server/client program where the server
could be present on any one of several machines on the
Ethernet.
If a client does a 'connect' to a machine that does not have
the server, an error is returned ('ECONNREFUSED'). This is
Ok, I'll try another.
The next time I get another error, ('EINVAL') even though this
time, it is trying to connect to the machine where the server
really is.
If I close the socket connection *after* the bad connection,
re-open it, and try the connect on the new machine, it works
fine.
It seems that when connect fails, it changes some internal flags
that need to be reset. Is there any way to make this not happen,
or reset it?
I also tried:
setsockopt ( sock, SOL_SOCKET, SO_REUSEADDR, (char *)0, 0);
As well as:
x = 1;
setsockopt ( sock, SOL_SOCKET, SO_REUSEADDR, &x, sizeof(x));
after the socket call and before the connect, but there was no
difference.
We don't have sources, and the documentation is pretty sketchy on
these areas.
Thanks in advance for any helpful hints....
Eric
"Has anyone seen... | Eric Rose
a dog dyed dark green?" | MRS Technology, Acton, MA.
- B-52's | (617)264-4588
| ...genrad \
| >- !mrst!esr
| ...necis /coltoff@PRC.Unisys.COM (Joel Coltoff) (08/10/88)
I've got an application that uses a server to spawn a child.
For testing purposes I have a tty attached to the child as well.
My server does an
execl( "/usr/bin/cmdtool", "cmdtool", "/usr/acct/coltoff/bin/conf", 0 );
This way I can enter debugging commands and display error messages.
From another window I send data down the socket to the child. I am
running into problems when /usr/acct/coltoff/bin/conf tries to find the
descriptor to use as the socket. I know for a fact that in the server
it's fileno is 3. Since I was real careful to close() all unneeded
files I figured what I could do in the child was do a stat() on all
descriptors until I got back a -1 or found one that had the S_IFSOCK
bit set. The closest I get is S_IFIFO. I seems to work so I forged
blindly ahead putting off the inevitable search for an answer until
later. That happened sooner than I thought it would.
Now I am trying to get this code to work under X11 and want to
start an xterm instead of a cmdtool. The descriptor in the child
that used to be S_IFIFO is now S_IFREG and this doesn't work at all.
With that background here are my questions. How does a child program
go about finding out what descriptor is the socket from it's parent?
Should the child do a dup() on it right away so that if it does
any open() calls the socket isn't clobbered? For the brave among
you, why does the program behave one way under X11R2 and another
under suntools?
Thanks in advance.
--
- Joel
{psuvax1,sdcrdcf}!burdvax!coltoff (UUCP)
coltoff@burdvax.prc.unisys.com (ARPA)