Re: Possible bug with UDP and SO_REUSEADDR. Was Re: [PATCH] zerocopy NFS updated

[Terje Eggestad <terje.eggestad@scali.com>]

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'course



On Fri, 2002-04-26 at 04:43, David S. Miller wrote:
>    From: Terje Eggestad <terje.eggestad@scali.com>
>    Date: 25 Apr 2002 14:37:44 +0200
> 
>    However writing a test server that stand in blocking wait on a UDP
>    socket, and start two instances of the server it's ALWAYS the server
>    last started that get the udp message, even if it's not in blocking
>    wait, and the first started server is. 
>    
>    Smells like a bug to me, this behavior don't make much sence. 
>    
>    Using stock 2.4.17.
> 
> Can you post your test server/client application so that I
> don't have to write it myself and guess how you did things?
> 
> Thanks.
> -
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-- 
_________________________________________________________________________

Terje Eggestad                  mailto:terje.eggestad@scali.no
Scali Scalable Linux Systems    http://www.scali.com

Olaf Helsets Vei 6              tel:    +47 22 62 89 61 (OFFICE)
P.O.Box 150, Oppsal                     +47 975 31 574  (MOBILE)
N-0619 Oslo                     fax:    +47 22 62 89 51
NORWAY            
_________________________________________________________________________

[-- Attachment #2: client.c --]
[-- Type: text/x-c, Size: 1336 bytes --]

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#include <unistd.h>
#include <fcntl.h>

#define BS 4096*3
main(int argc, char ** argv)
{
  int s, n, ns, cond, len, rc, val;
  short port = 6767;
  struct sockaddr_in mysock;
  char buffer[BS];
  char addr[16], * host;
  time_t t; 
  struct hostent * he;
  s = socket(PF_INET, SOCK_DGRAM, 0);

  if (argc >= 2) {
    host = argv[1];
  } else {
    printf ("error\n");
  };

  if (argc >= 3) {
    port = atoi(argv[2]);
  };

  mysock.sin_family = AF_INET;
  mysock.sin_port = htons(port);
  he = gethostbyname(host);
  if (he == NULL) exit(9);

  printf ("host  %s : %s, %d %#x \n", host, he->h_name, he->h_addrtype, he->h_addr_list[0]);
  memcpy(&mysock.sin_addr.s_addr, he->h_addr_list[0], he->h_length);
  
  printf("\n");
  time(&t);
  rc = sprintf(buffer, "%d : %s : hei hei", getpid(), ctime(&t));
  len = sizeof(struct sockaddr_in);
  inet_ntop(AF_INET, &mysock.sin_addr.s_addr, addr, 16);
  printf("sento: %s:%d =\"%s\"\n", addr, ntohs(mysock.sin_port), buffer);
  rc = sendto(s, buffer, rc, 0, (struct sockaddr*) &mysock, len); 

};

/* 
 * Local variables:
 *  compile-command: "gcc -g  -o client client.c"
 * End:
 */

[-- Attachment #3: server.c --]
[-- Type: text/x-c, Size: 1351 bytes --]

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <unistd.h>
#include <fcntl.h>

#define BS 4096*3
main(int argc, char ** argv)
{
  int s, n, ns, cond, len, rc, val;
  short port = 6767;
  struct sockaddr_in mysock, peeraddr;
  char buffer[BS];
  char addr[16];
 
  s = socket(PF_INET, SOCK_DGRAM, 0);

  if (argc >= 2) {
    port = atoi(argv[1]);
  };

  mysock.sin_family = AF_INET;
  mysock.sin_port = htons(port);
  mysock.sin_addr.s_addr = INADDR_ANY;
  
  val = 1;
  rc = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(int));
  printf ("setsockopt => %d (%d)\n", rc, errno);
  
  rc = bind(s, (struct sockaddr*) &mysock, sizeof(struct sockaddr_in));
  printf ("bind => %d (%d)\n", rc, errno);
  

  while(1) {

    printf("\n");
    len = sizeof(struct sockaddr_in);
    rc = recvfrom(s, buffer, BS, 0, (struct sockaddr*) &peeraddr, &len); 

    if (rc == -1) printf("recvfrom returned %d (%d)\n", rc, errno);
    else {
      inet_ntop(AF_INET, &peeraddr.sin_addr.s_addr, addr, 16);
      printf("recvfrom got from %s:%d =\"%s\"\n", addr, ntohs(peeraddr.sin_port), buffer);
    };
    sleep(1);
  };
};

/* 
 * Local variables:
 *  compile-command: "gcc -g  -o server server.c"
 * End:
 */