For starters, you need to initialize your "peer" variable properly.
On Tue, 17 Apr 2001, Rafael MatíasHernández wrote:
> Hello. I have a problem running this code under linux 2.4.3: the
> "recv" function does not block, but instead returns "0". The same code
> under linux 2.2.19 will block until a datagram is received. I think
> the problem is in the shutdown code (although the socket is not
> connected). Any idea?
>
>
> #include <unistd.h>
> #include <stdio.h>
> #include <netinet/in.h>
> #include <sys/types.h>
> #include <sys/socket.h>
>
> int main(void)
> {
> int so, so2, res;
> struct sockaddr_in peer;
> unsigned char buffer[1024];
>
> so = socket(AF_INET, SOCK_DGRAM, 0);
> memset(&peer, 0, sizeof(peer));
> bind(so, &peer, sizeof(peer));
>
> so2 = dup(so);
> /* receive disallowed. Returns -1 = ENOTCONN */
> /* Does shutdown refer both to so and so2? */
> shutdown(so, 0);
>
> /* Under linux 2.4.3 this will not block, and it will return 0
> (success!).
> Under 2.2.19, this will block */
> res = recv(so2, buffer, sizeof(buffer), 0);
> printf("Result = %d\n", res);
> return 0;
> }
>
> /************** Under 2.4.3 */
> // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
> // bind(3, {sin_family=AF_UNSPEC, {sa_family=0, sa_data="\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16) = 0
> // dup(3) = 4
> // shutdown(3, 0 /* receive */) = -1 ENOTCONN (Transport endpoint is not connected)
> // recv(4, "", 1024, 0) = 0
>
> --
> Salu2
> -
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>
--
Tuan Hoang
The MITRE Corporation
tuan@optimus.mitre.org
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