Re: [patch] Fix closing socket twice bug in netcat program
Hi bluhm,
Very sorry for my remiss! Updated, thanks!
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.c10 Aug 2018 17:15:22 - 1.192
+++ netcat.c6 Sep 2018 10:10:07 -
@@ -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");
}
On 9/6/2018 8:53 PM, Alexander Bluhm wrote:
> On Thu, Sep 06, 2018 at 06:27:15PM +0800, Nan Xiao wrote:
>> @@ -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)
>
> This has to be (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");
>> }
>
> otherwise OK bluhm@
>
--
Best Regards
Nan Xiao(肖楠)
Re: [patch] Fix closing socket twice bug in netcat program
On Thu, Sep 06, 2018 at 06:27:15PM +0800, Nan Xiao wrote:
> @@ -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)
This has to be (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");
> }
otherwise OK bluhm@
Re: [patch] Fix closing socket twice bug in netcat program
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.c10 Aug 2018 17:15:22 - 1.192
+++ netcat.c6 Sep 2018 10:10:07 -
@@ -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)
Re: [patch] Fix closing socket twice bug in netcat program
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
Re: [patch] Fix closing socket twice bug in netcat program
Ping tech@,
Could anyone spare a minute to check this patch? I think it is indeed a bug.
On 9/4/2018 1:01 PM, Nan Xiao wrote:
> Hi tech@,
>
> 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:
>
> 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 - 1.192
> +++ netcat.c 4 Sep 2018 04:51:55 -
> @@ -622,9 +622,10 @@ main(int argc, char *argv[])
> }
> close(connfd);
> }
> - if (family != AF_UNIX)
> + if (family != AF_UNIX) {
> close(s);
> - else if (uflag) {
> + s = -1;
> + } else if (uflag) {
> if (connect(s, NULL, 0) < 0)
> err(1, "connect");
> }
>
> Thanks!
>
--
Best Regards
Nan Xiao(肖楠)
[patch] Fix closing socket twice bug in netcat program
Hi tech@,
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:
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.c10 Aug 2018 17:15:22 - 1.192
+++ netcat.c4 Sep 2018 04:51:55 -
@@ -622,9 +622,10 @@ main(int argc, char *argv[])
}
close(connfd);
}
- if (family != AF_UNIX)
+ if (family != AF_UNIX) {
close(s);
- else if (uflag) {
+ s = -1;
+ } else if (uflag) {
if (connect(s, NULL, 0) < 0)
err(1, "connect");
}
Thanks!
--
Best Regards
Nan Xiao
