Date: Fri, 14 Sep 2001 20:07:50 -0400 From: Barney Wolff <barney@databus.com> To: Barney Wolff <barney@databus.com> Cc: Jos Backus <josb@cncdsl.com>, freebsd-net@FreeBSD.ORG Subject: Re: How does getsockname() work? Message-ID: <20010914200750.A1784@tp.databus.com> In-Reply-To: <20010914165555.A150@tp.databus.com>; from barney@databus.com on Fri, Sep 14, 2001 at 04:55:55PM -0400 References: <20010914122357.A49323@lizzy.bugworks.com> <20010914165555.A150@tp.databus.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Oh yeah - you have to initialize local_len to the max length you
can accept. Whatever you took this code from either doesn't
work reliably or you copied it wrong.
Barney
On Fri, Sep 14, 2001 at 04:55:55PM -0400, Barney Wolff wrote:
> You're using htons on an int. Try not doing that.
> Barney Wolff
>
> On Fri, Sep 14, 2001 at 12:23:57PM -0700, Jos Backus wrote:
> > I am seeing the following difference between FreeBSD and Solaris when using
> > the attached program, which uses getsockname().
> > I am using the following command to test this program:
> >
> > snmpwalk -p 1234 <host> public
> >
> > <host> being either goldenbytes or taiko.
> >
> > On FreeBSD 4 I see:
> >
> > goldenbytes:~/udp% ./udp &
> > [1] 64015
> > goldenbytes:~/udp% received on 0.0.0.0:0
> > received 37 bytes from 157.57.212.23:1446
> > received on 0.0.0.0:0
> > received 37 bytes from 157.57.212.23:1446
> > received on 0.0.0.0:0
> > received 37 bytes from 157.57.212.23:1446
> > received on 0.0.0.0:0
> > received 37 bytes from 157.57.212.23:1446
> >
> > On Solaris 7 I see:
> >
> > taiko:~/udp% ./udp &
> > [1] 21129
> > taiko:~/udp% received on 0.0.0.0:1234
> > received 37 bytes from 157.57.212.23:1448
> > received on 0.0.0.0:1234
> > received 37 bytes from 157.57.212.23:1448
> > received on 0.0.0.0:1234
> > received 37 bytes from 157.57.212.23:1448
> > received on 0.0.0.0:1234
> > received 37 bytes from 157.57.212.23:1448
> >
> > The 0.0.0.0 is caused by using INADDR_ANY as the binding address; what I don't
> > understand is why Solaris shows the portnumber whereas FreeBSD doesn't. Surely
> > I am doing something wrong, but what?
> >
> > Thanks,
> > --
> > Jos Backus _/ _/_/_/ Santa Clara, CA
> > _/ _/ _/
> > _/ _/_/_/
> > _/ _/ _/ _/
> > josb@cncdsl.com _/_/ _/_/_/ use Std::Disclaimer;
>
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <unistd.h>
> > #include <string.h>
> > #include <errno.h>
> > #include <sys/socket.h>
> > #include <netinet/in.h>
> > #include <arpa/inet.h>
> >
> > #define PDU_SIZE 1500
> >
> > struct sock {
> > int fport;
> > int fsockfd;
> > long sockbuflen;
> > };
> >
> > static int
> > init_sock(ctx)
> > struct sock *ctx;
> > {
> > struct sockaddr_in local_address;
> >
> > bzero(&local_address, sizeof local_address);
> > local_address.sin_family = AF_INET;
> > local_address.sin_addr.s_addr = htonl(INADDR_ANY);
> > local_address.sin_port = htons(ctx->fport);
> >
> > if ((ctx->fsockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
> > fprintf(stderr, "socket(): %s\n", strerror(errno));
> > exit(1);
> > }
> > if (bind(ctx->fsockfd,
> > (struct sockaddr *)&local_address, sizeof local_address) < 0) {
> > fprintf(stderr, "bind(): %s\n", strerror(errno));
> > exit(1);
> > }
> > }
> >
> > static int
> > receive(ctx)
> > struct sock *ctx;
> > {
> > unsigned char fpdu[PDU_SIZE];
> > struct sockaddr_in remote_address;
> > struct sockaddr_in local_address;
> > int i, len, n, local_len;
> >
> > while (1) {
> > len = sizeof remote_address;
> > if ((n = recvfrom(ctx->fsockfd, (char *)fpdu,
> > sizeof(fpdu), 0,
> > (struct sockaddr *)&remote_address, &len)) == -1) {
> > fprintf(stderr, "recvfrom(): %s\n", strerror(errno));
> > exit(1);
> > }
> > if (getsockname(ctx->fsockfd, (struct sockaddr *)&local_address,
> > &local_len) == -1) {
> > fprintf(stderr, "getsockname(): %s\n", strerror(errno));
> > exit(1);
> > }
> > if (n > PDU_SIZE) {
> > fprintf(stderr, "Warning: %d excess bytes discarded\n",
> > n - PDU_SIZE);
> > n = PDU_SIZE;
> > }
> > if (len != sizeof remote_address) {
> > fprintf(stderr, "recvfrom() return address length %d - expected %d\n",
> > len, sizeof remote_address);
> > exit(1);
> > }
> > fprintf(stderr, "received on %s:%d\n",
> > inet_ntoa(local_address.sin_addr),
> > (int)ntohs(local_address.sin_port));
> > fprintf(stderr, "received %d bytes from %s:%d\n",
> > n,
> > inet_ntoa(remote_address.sin_addr),
> > (int)ntohs(remote_address.sin_port));
> > }
> > }
> >
> > int
> > main(int ac, char *av[])
> > {
> > struct sock s;
> >
> > s.fport = 1234;
> > s.sockbuflen = 65536;
> >
> > init_sock(&s);
> >
> > receive(&s);
> > }
>
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-net" in the body of the message
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010914200750.A1784>