staticd: add non-uSID SRv6 SID behaviors

[maxime-leroy]

Extend the srv6 sid CLI to support non-uSID SRv6 endpoint behaviors (End, End_X, End_DT6, End_DT4, End_DT46), including VRF/interface/nexthop handling when applicable. The CLI keyword End_X represents the SRv6 End.X behavior (dot replaced by underscore for CLI token parsing).

[ton31337]

Documention update is needed too?

[maxime-leroy]

Indeed, a documentation update is needed.

Anyway, it turns out the situation is more complex than expected after further testing.
The show segment-routing srv6 sid command does not behave the same when the locator has behavior usid configured versus when it doesn’t.

Example with behavior usid on the locator:

f915aef81415# configure
f915aef81415(config)# segment-routing
f915aef81415(config-sr)# srv6
f915aef81415(config-srv6)# static-sids
f915aef81415(config-srv6-sids)# sid fcbb:bbbb:1:fe01::/64 locator LOC1 behavior uDT4 vrf Vrf1
f915aef81415(config-srv6-sids)# exit
f915aef81415(config-srv6)# locators
f915aef81415(config-srv6-locators)# locator LOC1
f915aef81415(config-srv6-locator)# prefix fcbb:bbbb:1::/48
f915aef81415(config-srv6-locator)# behavior usid
f915aef81415(config-srv6-locator)# do show segment-routing srv6 sid
SID Behavior Context Daemon/Instance Locator AllocationType

---

fcbb:bbbb:1:fe01:: uDT4 VRF 'Vrf1' static(0) LOC1 explicit

Example without behavior usid on the locator

f915aef81415# configure
f915aef81415(config)# segment-routing
f915aef81415(config-sr)# srv6
f915aef81415(config-srv6)# static-sids
f915aef81415(config-srv6-sids)# sid fcbb:bbbb:1:fe01::/64 locator LOC1 behavior uDT4 vrf Vrf1
f915aef81415(config-srv6-sids)# exit
f915aef81415(config-srv6)# locators
f915aef81415(config-srv6-locators)# locator LOC1
f915aef81415(config-srv6-locator)# do show segment-routing srv6 sid
SID Behavior Context Daemon/Instance Locator AllocationType

---

fcbb:bbbb:1:fe01:: End.DT4 VRF 'Vrf1' static(0) LOC1 explicit

Internally, do_show_srv6_sid_json() uses different functions to format the SID behavior depending on whether the locator uses a uSID SID format:

447│ json_object_string_addf(json_sid, "sid", "%pI6", &entry->sid_value);
448├───────────────> if ((entry->locator->sid_format &&
449│ entry->locator->sid_format->type == SRV6_SID_FORMAT_TYPE_USID) ||
450│ (!entry->locator->sid_format &&
451│ CHECK_FLAG(entry->locator->flags, SRV6_LOCATOR_USID))) {
452│ json_object_string_add(json_sid, "behavior",
453│ show_srv6_sid_seg6_action(sid_ctx->ctx.behavior));
454│ } else {
455│ json_object_string_add(json_sid, "behavior",
456│ seg6local_action2str(sid_ctx->ctx.behavior));
457│ }

However, in zebra, the installed nexthop always uses the NEXT_CSID flavor.

So currently staticd always tries to install SIDs as uSID format, regardless of the locator.

To properly support non-uSID locators, we have two possible approaches:

Option A — Automatic behavior selection

• If the locator is not uSID → automatically use classic End.DT4
• If the locator is uSID → automatically use uDT4

Option B — Strict validation

• Reject mismatched combinations such as:
  • uDT4 with a non-uSID locator
  • End.DT4 with a uSID locator

Another issue: CLI parsing prevents the use of a dot (.) in non-uSID behaviors (e.g., End.DT4).
I had to temporarily switch to an alternative form (e.g., End_DT4) but changing WORD in the lexer breaks other commands.