Hi bluhm,
Thanks for your reply! I think your method is better, and I update the
patch:
Index: netcat.c
===================================================================
RCS file: /cvs/src/usr.bin/nc/netcat.c,v
retrieving revision 1.192
diff -u -p -r1.192 netcat.c
--- netcat.c 10 Aug 2018 17:15:22 -0000 1.192
+++ netcat.c 6 Sep 2018 10:10:07 -0000
@@ -564,8 +564,11 @@ main(int argc, char *argv[])
}
/* Allow only one connection at a time, but stay alive. */
for (;;) {
- if (family != AF_UNIX)
+ if (family != AF_UNIX) {
+ if (s == -1)
+ close(s);
s = local_listen(host, uport, hints);
+ }
if (s < 0)
err(1, NULL);
if (uflag && kflag) {
@@ -622,9 +625,7 @@ main(int argc, char *argv[])
}
close(connfd);
}
- if (family != AF_UNIX)
- close(s);
- else if (uflag) {
+ if (family == AF_UNIX && uflag) {
if (connect(s, NULL, 0) < 0)
err(1, "connect");
}
Thanks!
On 9/6/2018 5:07 AM, Alexander Bluhm wrote:
> On Tue, Sep 04, 2018 at 01:01:38PM +0800, Nan Xiao wrote:
>> Before netcat program exits, it will check whether s is -1, and close
>> socket if s is not -1:
>>
>> if (s != -1)
>> close(s);
>>
>> The following patch fixes the issue that netcat will close socket twice
>> if it works as a server:
>
> I think it is a bug, but should be fixed differently. The netstat
> code has a lot of if and else for all the use cases. Adding a s =
> -1 at one place makes it even more confusing.
>
> In general main() does not reset s to -1, it isets it at the
> beginning. Look at the client side. There we close at the beginning
> of the loop:
>
> /* Cycle through portlist, connecting to each port. */
> for (s = -1, i = 0; portlist[i] != NULL; i++) {
> if (s != -1)
> close(s);
>
> So on the server side we should do the same, otherwise the code
> will get more and more messy. Use the same concept everywhere.
> I think this would be better:
>
> /* Allow only one connection at a time, but stay alive. */
> for (;;) {
> if (family != AF_UNIX) {
> if (s != -1)
> close(s);
> s = local_listen(host, uport, hints);
> }
>
> bluhm
>
--
Best Regards
Nan Xiao(肖楠)
