freebsd stable - Jan 2004 - getsockname()

Hi,
I have a problem that is similar to the problem described in 
http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/22868

My program, that opens a tcp socket and binds to INADDR_ANY:0, 
getsockname() returns either the correct answer
or, for some time, a wrong answer, see below

(this is of course not my program, just some code that does the same)

--- snipp ---
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main()
{
     int sock, len;
     struct sockaddr_in addr, foo;

     if((sock=socket(AF_INET, SOCK_STREAM, 0))<0)
     {
         exit(0);
     }

     memset(&addr, 0, sizeof(struct sockaddr_in));
     addr.sin_family = AF_INET;
     addr.sin_addr.s_addr = INADDR_ANY;
     addr.sin_port = htons(0);

     if(bind(sock, (struct sockaddr *) &addr, sizeof(struct 
sockaddr_in))<0)
     {
         perror("bind");
         exit(0);
     }

     if(listen(sock, 5)<0)
     {
         perror("listen");
         exit(0);
     }

     getsockname(sock, (struct sockaddr *) &foo, &len);
     fprintf(stderr, "listening on %s:%d\n", inet_ntoa(foo.sin_addr), 
ntohs(foo.sin_port));

     return 0;
}

--- snap ---


$ ./a.out
listening on 86.186.4.40:49087
$ ./a.out
listening on 0.0.0.0:3810

regards,
Chris

PS: It is even stranger than I thought, I compiled this program: gcc -o 
freebsd freebsd.c and ran it serveral times:
  $ ./freebsd
listening on 86.186.4.40:49087
  $ mv freebsd a.out
  $ ./a.out
listening on 0.0.0.0:4364
  $ mv a.out freebsd
  $ ./freebsd
listening on 86.186.4.40:49087
  $ mv freebsd a.out
  $ ./a.out
listening on 0.0.0.0:4604

> (this is of course not my program, just some code that does the same)
>
> --- snipp ---
> #include <stdio.h>
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <string.h>
> #include <stdlib.h>
> #include <netinet/in.h>
> #include <arpa/inet.h>
>
> int main()
> {
>      int sock, len;
	Okay, you haven't set the value of 'len'.
>      struct sockaddr_in addr, foo;
>
>      if((sock=socket(AF_INET, SOCK_STREAM, 0))<0)
>      {
>          exit(0);
>      }
>
>      memset(&addr, 0, sizeof(struct sockaddr_in));
>      addr.sin_family = AF_INET;
>      addr.sin_addr.s_addr = INADDR_ANY;
>      addr.sin_port = htons(0);
>
>      if(bind(sock, (struct sockaddr *) &addr, sizeof(struct
> sockaddr_in))<0)
>      {
>          perror("bind");
>          exit(0);
>      }
>
>      if(listen(sock, 5)<0)
>      {
>          perror("listen");
>          exit(0);
>      }
>
>      getsockname(sock, (struct sockaddr *) &foo, &len);
	Hmm, you still haven't set the value of 'len'. And you ignore the
return
value of 'getsockname'.
>      fprintf(stderr, "listening on %s:%d\n",
inet_ntoa(foo.sin_addr),
> ntohs(foo.sin_port));
>
>      return 0;
> }
> $ ./a.out
> listening on 86.186.4.40:49087
> $ ./a.out
> listening on 0.0.0.0:3810
	Fix those two bugs and see if you still have a problem.

	DS

Christian Klein wrote:
> 
> Am Mittwoch, 07.01.04, um 23:02 Uhr (Europe/Berlin) schrieb Lev Walkin:
> 
>> len = sizeof(*foo);
> 
> 
> Oh, thanks a lot!
> I should have read the manual more careful!
> I thought then len parameter would be filled by getsockname().
It is. But its original value is being used too.

-- 
Lev Walkin
vlm@netli.com