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

Terje Eggestad
2002-04-26T07:39:01Z

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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 --]
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#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 --]
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#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:
*/