Date: Tue, 03 Jul 2001 19:54:59 +0200 From: Juan Fco Rodriguez Hervella <jrh@it.uc3m.es> To: Lista <freebsd-net@freebsd.org> Subject: ftp.c understanding Message-ID: <3B4206F3.E75B1E11@it.uc3m.es>
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Hi:
Inside /usr/src/usr.bin/ftp/ftp.c:initconn(), I can not understand the
following piece of code:
My problem is with SO_REUSEADDR. The first time,
sendport = -1, so data_addr.su_port = 0 and SO_REUSEADDR
is not call. Then the port is send to the server.
If something goes wrong, sendport =0 && goto noport.
This time, it is called to SO_REUSEADDR,
why is it called now and not the first time ?
Also, if sendport = 0 the port is not send to the server, then
how is it openned the data connection ? By default, the data
connection is on port 20, but the code does not specified any
port at bind() call.
--
*********************************
Juan F. Rodriguez Hervella
Universidad Carlos III de Madrid
********************************
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filename="code.c"
noport:
data_addr = myctladdr;
if (sendport)
data_addr.su_port = 0; /* let system pick one */
if (data != -1)
(void)close(data);
data = socket(data_addr.su_family, SOCK_STREAM, 0);
if (data < 0) {
warn("socket");
if (tmpno)
sendport = 1;
return (1);
}
if (!sendport)
if (setsockopt(data, SOL_SOCKET, SO_REUSEADDR, (char *)&on,
sizeof(on)) < 0) {
warn("setsockopt (reuse address)");
goto bad;
}
if (bind(data, (struct sockaddr *)&data_addr, data_addr.su_len) < 0) {
warn("bind");
goto bad;
}
if (options & SO_DEBUG &&
setsockopt(data, SOL_SOCKET, SO_DEBUG, (char *)&on,
sizeof(on)) < 0)
warn("setsockopt (ignored)");
len = sizeof(data_addr);
if (getsockname(data, (struct sockaddr *)&data_addr, &len) < 0) {
warn("getsockname");
goto bad;
}
if (listen(data, 1) < 0)
warn("listen");
if (sendport) {
bla...bla...bla..
skip_port:
if (result == ERROR && sendport == -1) {
sendport = 0;
tmpno = 1;
goto noport;
}
return (result != COMPLETE);
}
if (tmpno)
sendport = 1;
return (0);
bad:
(void)close(data), data = -1;
if (tmpno)
sendport = 1;
return (1);
}
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