: Add support for multipath route realms

[IPROUTE]: Add support for multipath route realms

Routing realms exist per nexthop, but iproute currently only allows to send a single route realm, which is refused by the kernel for multipath routes. Add support for specifying per nexthop realms. Old kernels only return the first realm back to userspace when dumping, so the others can't be displayed, besides that it will also behave correctly on old kernels.

old kernel:

1.2.3.4 realm 1
nexthop dev dummy0 weight 1
nexthop dev dummy1 weight 1
nexthop dev dummy2 weight 1
nexthop dev dummy3 weight 1

new kernel:

1.2.3.4
nexthop realm 1 dev dummy0 weight 1
nexthop realm 2 dev dummy1 weight 1
nexthop realm 3 dev dummy2 weight 1
nexthop realm 4 dev dummy3 weight 1

route queries on both old and new kernel:

1.2.3.4 dev dummy0 src 10.0.0.1 realm 1

    cache  mtu 1500 advmss 1460 metric 10 64
1.2.3.4 dev dummy1  src 10.0.0.1 realm 2
    cache  mtu 1500 advmss 1460 metric 10 64
1.2.3.4 dev dummy2  src 10.0.0.1 realm 3
    cache  mtu 1500 advmss 1460 metric 10 64
1.2.3.4 dev dummy3  src 10.0.0.1 realm 4
    cache  mtu 1500 advmss 1460 metric 10 64

---
commit dbc39a8d37d658776a8959d2393b1047ea124436
tree be59669a06709aaa3b194f050529fe3986928dc8
parent 8f8a36487119a3cd1afe86a9649704aca088567b
author Patrick McHardy <[email protected]> Tue, 25 Jul 2006 05:55:36 +0200 committer Patrick McHardy <[email protected]> Tue, 25 Jul 2006 05:55:36 +0200

 ip/iproute.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

index a43c09e..3544f02 100644
@@ -557,6 +557,18 @@ #endif
 							    RTA_DATA(tb[RTA_GATEWAY]),
 							    abuf, sizeof(abuf)));
 				}
+				if (tb[RTA_FLOW]) {
+					__u32 to = *(__u32*)RTA_DATA(tb[RTA_FLOW]);
+					__u32 from = to>>16;
+					to &= 0xFFFF;
+					fprintf(fp, " realm%s ", from ? "s" : "");
+					if (from) {
+						fprintf(fp, "%s/",
+							rtnl_rtrealm_n2a(from, b1, sizeof(b1)));
+					}
+					fprintf(fp, "%s",
+						rtnl_rtrealm_n2a(to, b1, sizeof(b1)));
+				}
 			}
 			if (r->rtm_flags&RTM_F_CLONED && r->rtm_type == RTN_MULTICAST) {
 				fprintf(fp, " %s", ll_index_to_name(nh->rtnh_ifindex));

@@ -606,6 +618,13 @@ int parse_one_nh(struct rtattr *rta, str
 			rtnh->rtnh_hops = w - 1;
 		} else if (strcmp(*argv, "onlink") == 0) {
 			rtnh->rtnh_flags |= RTNH_F_ONLINK;
+		} else if (matches(*argv, "realms") == 0) {
+			__u32 realm;
+			NEXT_ARG();
+			if (get_rt_realms(&realm, *argv))
+				invarg("\"realm\" value is invalid\n", *argv);
+			rta_addattr32(rta, 4096, RTA_FLOW, realm);
+			rtnh->rtnh_len += sizeof(struct rtattr) + 4;
 		} else
 			break;
 	}

This really looks like papering over fundamental brokenness of IP_ROUTE_MULTIPATH_CACHED since you wouldn't otherwise get these entries in the routing cache.

This reminds me that I better revisit the reasons that people gave for actually using IP_ROUTE_MULTIPATH_CACHED the last time we tried to get rid of it.

Cheers,

Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Actually it has nothing to do with MULTIPATH_CACHED, it didn't even use it in these tests unless I seriously mixed something up. The realm can be used by netfilter to find out which nexthop was chosen and bind the connection to this nexthop manually using CONNMARK and MARK.

Nevermind, I misread your changelog. Your patch is obviously not related to IP_ROUTE_MULTIPATH_CACHED :)

Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

On Tue, 25 Jul 2006 05:58:36 +0200
Patrick McHardy <[email protected]> wrote:

applied

Stephen Hemminger <[email protected]>
"And in the Packet there writ down that doome"

Have you had a chance to look at the time cleanup patches and the increased number of routing rule patch? Please let me know if you want me to resend.