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Re: Set route to interface
On Montag, 30. Dezember 2002 13:49, Gary Thomas wrote:
> On Mon, 2002-12-30 at 03:25, Roland Caßebohm wrote:
> > Hi,
> >
> > how can I set a route for a specific ip-address outside of the actual
> > configured network to a interface.
> >
> > For example eCos is configured as follows:
> >
> > ip-address: 192.168.50.100
> > netmask: 255.255.255.0
> > gateway: 192.168.50.1
> >
> > Now I want to send an udp-message to 192.168.1.30. I thought I could just
> > add a route for destination 192.168.1.30 to "eth0". If I try this under
> > linux it seems to work.
> > -> route add -host 192.168.1.30 dev eth0
> >
> > Under eCos I have tried the following (peer is 192.168.1.30):
> >
> > int addroute(struct sockaddr peer)
> > {
> > struct sockaddr *so_peer=&peer;
> > struct sockaddr_in *so_in_peer=(struct sockaddr_in *)&peer;
> > struct ecos_rtentry route;
> > struct sockaddr_in a;
> > struct sockaddr_in *addrp=&a;
> > char mask[4]={255,255,255,255};
> > char local[4]={192,168,50,100};
>
> These constructs are not portable at all. It would be much better to
> use one of the address conversion functions to set these fields.
Yes, this was just to make a short test.
>
> > int s;
> >
> > /* verify the destination is directly reachable */
> > if ((ifa_ifwithnet(so_peer)) == NULL) {
>
> Note: calling functions internal to the stack is very bad practice.
>
> > s = socket(AF_INET, SOCK_DGRAM, 0);
> > if (s < 0) {
> > VS_PERROR(1,"socket");
> > return VS_EERROR;
> > }
> >
> > memset(&route, 0, sizeof(route));
> > addrp->sin_family = AF_INET;
> > addrp->sin_port = 0;
> > addrp->sin_len = sizeof(*addrp);
> > addrp->sin_addr = so_in_peer->sin_addr;
> > memcpy(&route.rt_dst, addrp, sizeof(*addrp));
> > memcpy(&addrp->sin_addr.s_addr,mask,4);
> > memcpy(&route.rt_genmask, addrp, sizeof(*addrp));
> > /* use local ip as gateway to set route to "eth0" */
> > memcpy(&addrp->sin_addr.s_addr,local,4);
> > memcpy(&route.rt_gateway, addrp, sizeof(*addrp));
> >
> > route.rt_dev = "eth0";
> > route.rt_flags = RTF_UP;
>
> Have you tried this?
> route.rt_flags = RTF_UP|RTF_GATEWAY;
Yes, but it doesn't work. In both cases the ioctl() call succeds, but sendto()
to 192.168.1.30 fails.
>
> > route.rt_metric = 0;
> >
> > if (ioctl(s, SIOCADDRT, &route)) {
> > perror("SIOCADDRT");
> > if (errno != EEXIST) {
> > close(s);
> > return -1;
> > }
> > }
> > }
> >
> > close(s);
> > return 0;
> > }
> >
> > Thank you,
> >
> > Roland
> >
> > --
> > Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> > and search the list archive: http://sources.redhat.com/ml/ecos-discuss
--
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