[ECOS] Set route to interface

Roland Caßebohm roland.cassebohm@visionsystems.de
Mon Dec 30 09:26:00 GMT 2002


On Montag, 30. Dezember 2002 15:07, Gary Thomas wrote:
> On Mon, 2002-12-30 at 07:03, Roland Caßebohm wrote:
> > 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.
I have forgotten to set *addrp whith 0, so now sendto() succeds, but I can't 
see anything on the network (tcpdump).

>
> How about RTF_STATIC instead?
Does not change anything.

>
> Also, have you tried printing out the routing tables, to see if they
> look correct?  I added some functions which do that recently.
This was very helpfully, so I could see that somthing was wrong with addrp.
If I look at the routing table of my linux host, the host flag is set:

Kernel IP Routentabelle
Ziel            Router          Genmask         Flags Metric Ref    Use Iface
192.168.1.30    *               255.255.255.255 UH    0      0        0 eth0
192.168.50.0    *               255.255.255.0   U     0      0        0 eth0
default         192.168.50.1    0.0.0.0         UG    0      0        0 eth0

But if I use RTF_HOST with eCos, show_network_tables(printf) don't show this 
entry, but the entry seems to be there, because if try to add the routing 
entry again, I get EEXIST.
But there is no message on the network too.

I have althought tried it with netmask 255.255.255.0 instead of 
255.255.255.255. Then it works. The routing table looks as follows:

Routing tables
Destination     Gateway         Mask            Flags    Interface
127.0.0.0       127.0.0.1       255.0.0.0       UG       lo0      
192.168.1.0     192.168.1.0     255.255.255.0   U        eth0     
192.168.50.0    192.168.50.0    255.255.255.0   U        eth0

But this is not realy what I want, I want somthing like this:

Routing tables
Destination     Gateway         Mask            Flags    Interface
127.0.0.0       127.0.0.1       255.0.0.0       UG       lo0      
192.168.1.30    192.168.1.30    255.255.255.255 U        eth0     
192.168.50.0    192.168.50.0    255.255.255.0   U        eth0

>
> > > > 		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
> >
> > --
> > Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> > and search the list archive: http://sources.redhat.com/ml/ecos-discuss

-- 

___________________________________________________

VS Vision Systems GmbH, Industrial Image Processing
Roland Caßebohm
Aspelohe 27A, D-22848 Norderstedt, Germany
Mail: roland.cassebohm@visionsystems.de
http://www.visionsystems.de
___________________________________________________


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