Router advertisement & Router sollicitation #126

christophefontaine · 2025-01-14T15:06:35Z

Add router advertisement support, with basic configuration (lifetime, priority, interval, but no DNS, etc.).
Also answer to router sollicitation messages.

Depends on PR #112

rjarry · 2025-01-14T17:37:56Z

modules/ip6/cli/meson.build

@@ -5,4 +5,5 @@ cli_src += files(
  'address.c',
  'nexthop.c',
  'route.c',
+  'router_advertisement.c',


maybe s/router_advertisement.c/ra.c/ or at least router_advert.c?

rjarry · 2025-01-14T17:52:04Z

modules/ip6/cli/router_advertisement.c

+
+	ret = CLI_COMMAND(
+		IP6_SHOW_CTX(root),
+		"router-advertisment [IFACE]",


s/advertisment/advertisement/

But I think I prefer router-advert. What do you think?

even shorter ra ? Do you think it may be possible to have "short commands" in the CLI ?
So we could use both ra and router-advertisement ? (or to even accept partial commands ?)

Yes you can have token alternatives separated by pipes (without spaces)

"ra|router-advert|... [IFACE]"

No partial marching though. You need to explicitly list all alternatives to allow libecoli to build a token graph.

rjarry · 2025-01-14T17:54:23Z

modules/ip6/control/router_advertisement.c

+}
+void ndp_router_sollicit_input_cb(struct rte_mbuf *m) {


missing empty line

rjarry · 2025-01-14T17:56:34Z

modules/ip6/datapath/icmp6_input.c

@@ -89,6 +96,7 @@ static struct rte_node_register icmp6_input_node = {
 		[ICMP6_OUTPUT] = "icmp6_output",
 		[NEIGH_SOLICIT] = "ndp_ns_input",
 		[NEIGH_ADVERT] = "ndp_na_input",
+		[ROUTER_SOLICIT] = "control_output",


Is there no point in having an ndp_rs_input node for consistency with the other ndp types? You could perform sanity checks before sending the packet to slow path.

rjarry · 2025-01-14T17:58:19Z

modules/ip6/control/router_advertisement.c

+			ev_base, -1, EV_PERSIST | EV_FINALIZE, send_ra_cb, iface
+		);
+	} else if (event == IFACE_EVENT_PRE_REMOVE) {
+		event_free(ra_conf[iface->id].timer);


I'm not sure about that but should you call event_free_finalize?

rjarry · 2025-01-14T18:01:42Z

modules/ip6/control/router_advertisement.c

+		ra_conf[iface->id].timer = event_new(
+			ev_base, -1, EV_PERSIST | EV_FINALIZE, send_ra_cb, iface
+		);


I never recall this libevent api... Is this adding a 1s timer or do you need to "enable" it afterwards?

rjarry · 2025-01-14T18:03:53Z

modules/ip6/control/router_advertisement.c

+	ra->cur_hoplim = IP6_DEFAULT_HOP_LIMIT; // Default TTL for this network
+	ra->managed_addr = 0; // DHCPv6 is available
+	ra->other_config = 0; // DNS available, ...
+	ra->lifetime = rte_cpu_to_be_16(5); // Not a default router


is that in seconds? maybe worth a #define

Indeed, while the lifetime is in seconds, the other parameters below are in milliseconds...

The defines are created in the next commit, when the configuration is settable by the user.

ra_conf[req->iface_id].interval = RA_DEFAULT_INTERVAL; ra_conf[req->iface_id].lifetime = RA_DEFAULT_LIFETIME; ra_conf[req->iface_id].preference = RA_DEFAULT_PREFERENCE;

I'll use them in this commit.

rjarry · 2025-01-14T18:04:14Z

modules/ip6/control/router_advertisement.c

+	ra->reachable_time = rte_cpu_to_be_32(0);
+	ra->retrans_timer = rte_cpu_to_be_32(0);


Not essential, but RTE_BE32(0) would be better for constants.

rjarry · 2025-01-14T18:05:23Z

modules/ip6/control/router_advertisement.c

+	return api_out(0, len);
+}
+void ndp_router_sollicit_input_cb(struct rte_mbuf *m) {
+	uint16_t iface_id = mbuf_data(m)->iface->id;


Maybe we're missing some RFC checks for router solicitations?

I'll double check that.

We wrongly assumed that the data was still present when prepending an ip header. Rewrite the ip/ip6 header instead. Fixes: e27fab5 ("ip/ip6: post tcp/udp packets to loopback interface") Signed-off-by: Christophe Fontaine <[email protected]>

For VxLan tunnels, we need to register a specific destination udp port. Add a new node and api, and push all non-handled packets back to the management (loopback) interface, as done today. Signed-off-by: Christophe Fontaine <[email protected]>

BGP unnumbered relies on RA message to discover the local routers. Broadcast the simplest router advertisement message on ipv6 enabled interfaces. Additional options (DNS, ... ) may be added in the future. Signed-off-by: Christophe Fontaine <[email protected]>

Upon reception of a router sollicit message, trigger the existing timer to send immediately a router advertismement packet. Signed-off-by: Christophe Fontaine <[email protected]>

Add configuration knobs for RA messages. Instead of a hardcoded perdiodic message, allow a per-interface configuration. Signed-off-by: Christophe Fontaine <[email protected]>

The returned nexthop for a multicast route lookup doesn't have a defined iface. Yet, this nexthop is valid, and we can rely on the iface defined by the parent node to select the output iface. Signed-off-by: Christophe Fontaine <[email protected]>

christophefontaine marked this pull request as ready for review January 14, 2025 16:38

rjarry requested changes Jan 14, 2025

View reviewed changes

christophefontaine marked this pull request as draft January 14, 2025 20:56

christophefontaine added 6 commits January 15, 2025 08:16

loopback: rebuild ip/ip6 header

9fa7497

We wrongly assumed that the data was still present when prepending an ip header. Rewrite the ip/ip6 header instead. Fixes: e27fab5 ("ip/ip6: post tcp/udp packets to loopback interface") Signed-off-by: Christophe Fontaine <[email protected]>

l4: add udp port handler

fd3f9b6

For VxLan tunnels, we need to register a specific destination udp port. Add a new node and api, and push all non-handled packets back to the management (loopback) interface, as done today. Signed-off-by: Christophe Fontaine <[email protected]>

ip6: answer to router sollicit message

52c6b25

Upon reception of a router sollicit message, trigger the existing timer to send immediately a router advertismement packet. Signed-off-by: Christophe Fontaine <[email protected]>

ip6: router advertisement configuration

39dd3a3

Add configuration knobs for RA messages. Instead of a hardcoded perdiodic message, allow a per-interface configuration. Signed-off-by: Christophe Fontaine <[email protected]>

christophefontaine force-pushed the router_advertisement branch from 957b425 to 78f1bb6 Compare January 15, 2025 08:22

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Router advertisement & Router sollicitation #126

Router advertisement & Router sollicitation #126

christophefontaine commented Jan 14, 2025 •

edited

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		ra->reachable_time = rte_cpu_to_be_32(0);
		ra->retrans_timer = rte_cpu_to_be_32(0);

Router advertisement & Router sollicitation #126

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Router advertisement & Router sollicitation #126

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christophefontaine commented Jan 14, 2025 • edited Loading

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christophefontaine commented Jan 14, 2025 •

edited

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