gnrc/ipv6/nib: make ABR run-time configurable

[benpicco]

Contribution description

Currently all nodes compiled with gnrc_sixlowpan_border_router_default will act as an authoritative border router by default.

We have a setup with many wireless nodes that are all potential (authoritative) border routers (see #21080), but only one of them will be selected (at run-time) to do so.

This adds a NETOPT_6LO_ABR that can be used to enable / disable the authoritative border router functionality on an interface as well as a CONFIG_GNRC_IPV6_NIB_ABR to control the start-up default.

Testing procedure

Issues/PRs references

[miri64]

(also please don't hesitate to remind me each time there is a Hack'n'ACK around the corner ;-))

[OlegHahm]

So, the default behavior stays the same for a 6lbr but we can configure it to be non-authorative with this patch, right?

[benpicco]

Yes that's the idea.

[OlegHahm]

Ok, testing was successful. Do you mind to add some documentation somewhere?

[miri64]

I want to have a deeper look into this as the designated GNRC / NIB expert but that may take a while. For now soft-blocking. If I don't come to it until end of February, please dismiss my change request.

Now it's a hard block until https://github.com/RIOT-OS/RIOT/pull/21081#pullrequestreview-2543777622 is resolved ;-)

[benpicco]

So just move _start_search_rtr()/_stop_search_rtr() to a public header?

[miri64]

So just move _start_search_rtr()/_stop_search_rtr() to a public header?

I'd move the definition to them to a public header, but keep the declaration in nib.c, but yes.

[maribu]

Could you apply the following to fix the unit tests?

diff --git a/sys/net/crosslayer/netopt/netopt.c b/sys/net/crosslayer/netopt/netopt.c
index bfadebe8b6..a8cae13ff7 100644
--- a/sys/net/crosslayer/netopt/netopt.c
+++ b/sys/net/crosslayer/netopt/netopt.c
@@ -91,6 +91,7 @@ static const char *_netopt_strmap[] = {
     [NETOPT_TX_RETRIES_NEEDED]     = "NETOPT_TX_RETRIES_NEEDED",
     [NETOPT_6LO]                   = "NETOPT_6LO",
     [NETOPT_6LO_IPHC]              = "NETOPT_6LO_IPHC",
+    [NETOPT_6LO_ABR]               = "NETOPT_6LO_ABR",
     [NETOPT_BLE_CTX]               = "NETOPT_BLE_CTX",
     [NETOPT_CHECKSUM]              = "NETOPT_CHECKSUM",
     [NETOPT_PHY_BUSY]              = "NETOPT_PHY_BUSY",

[benpicco]

@miri64 your comments have been addressed.

[riot-ci]

Murdock results

:heavy_check_mark: PASSED

e58d3f709caf5be2dbd765df421c6d624d56c170 gnrc_ipv6_nib: add gnrc_ipv6_nib_{start,stop}_search_rtr()

Success	Failures	Total	Runtime
10916	0	10916	13m:50s

Artifacts

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