UDF yang model definition.

[srodd-nexthop]

Why I did it

Adds the YANG model for the new UDF (User-Defined Field) feature in SONiC. UDF allows ACLs to match on arbitrary byte offsets within a packet, enabling classification of protocols not covered by standard ACL fields (e.g., RoCEv2 BTH, GRE inner headers).

The companion orchagent implementation is in [sonic-net/sonic-swss#<4493#>]. This PR adds only the YANG schema.

Work item tracking

• Microsoft ADO (number only): N/A

How I did it

Added src/sonic-yang-models/yang-models/sonic-udf.yang defining two CONFIG_DB tables:

• UDF — UDF field definition. Keys: UDF_NAME. Fields: length (1–20), field_type (GENERIC|HASH), description.
• UDF_SELECTOR — per-packet-type extraction rule. Keys: UDF_NAME|SELECTOR_NAME. Fields: select and match, each a JSON-encoded object:
  • select → { base: L2|L3|L4, offset: 0–255 }
  • match → { l2_type, l2_type_mask, l3_type, l3_type_mask, gre_type, gre_type_mask, l4_dst_port, l4_dst_port_mask, priority }

UDF_SELECTOR.UDF_NAME is a leafref to UDF.UDF_NAME.

Also updated:

• src/sonic-yang-models/setup.py to register the new module.
• src/sonic-yang-models/tests/files/sample_config_db.json with a UDF + UDF_SELECTOR example for validation.

How to verify it

cd src/sonic-yang-models
python3 setup.py test

The sample_config_db.json additions exercise the new leafrefs and the JSON-string fields; validation should pass cleanly.

Which release branch to backport (provide reason below if selected)

Not a backport — new feature.

• 202305
• 202311
• 202405
• 202411
• 202505
• 202511

Tested branch (Please provide the tested image version)

• master

Description for the changelog

Add YANG model for UDF (UDF and UDF_SELECTOR tables) to support ACL matching on user-defined byte offsets.

[linux-foundation-easycla]

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[mssonicbld]

/azp run Azure.sonic-buildimage

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