[ewg] Re: [PATCH] link-local address fix for rdma_resolve_addr

[David J. Wilder]

On Wed, 2009-10-14 at 13:09 Jason Gunthorpe wrote:

> So, it tries to match the source addr to the addrs bound to the
> device, which is wrong - that isn't how the ip stack works.

> You can patch this up a little bit by fixing up addr_resolve_local to
> set sin6_scope_ip.

I found the bug in addr_resolve_local().  (more comments below)

--- addr.c.1759	2009-10-13 15:57:48.000000000 -0500
+++ addr.c.ip_local	2009-10-15 14:03:50.000000000 -0500
@@ -390,14 +390,17 @@ static int addr_resolve_local(struct soc
 	case AF_INET6:
 	{
 		struct in6_addr *a;
+		int found = 0;
 
 		for_each_netdev(&init_net, dev)
 			if (ipv6_chk_addr(&init_net,
 					  &((struct sockaddr_in6 *) dst_in)->sin6_addr,
-					  dev, 1))
+					  dev, 1)){
+				found = 1;
 				break;
+			}
 
-		if (!dev)
+		if (!found)
 			return -EADDRNOTAVAIL;
 
 		a = &((struct sockaddr_in6 *) src_in)->sin6_addr;
@@ -406,6 +409,8 @@ static int addr_resolve_local(struct soc
 			src_in->sa_family = dst_in->sa_family;
 			((struct sockaddr_in6 *) src_in)->sin6_addr =
 				((struct sockaddr_in6 *) dst_in)->sin6_addr;
+			((struct sockaddr_in6 *) src_in)->sin6_scope_id =
+                                ((struct sockaddr_in6 *) dst_in)->sin6_scope_id;
 			ret = rdma_copy_addr(addr, dev, dev->dev_addr);
 		} else if (ipv6_addr_loopback(a)) {
 			ret = rdma_translate_ip(dst_in, addr);


> But really the correct thing to do is to remove addr_resolve_local and
> place the source address into the struct flowi and use the result of
> the route lookup to bind to the source device, and set the source
> address if it is unset.

Sorry I don't get it..
Are you saying that ip6_route_output() will resolve the address even if
it is a link-local address bound to my own interface? Therefor
addr_resolve_local() is not needed.