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{
    "id": 2219290,
    "url": "http://patchwork.ozlabs.org/api/covers/2219290/?format=api",
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        "id": 26,
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        "name": "Netfilter Development",
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    "msgid": "<20260402184320.14862-1-phil@nwl.cc>",
    "list_archive_url": null,
    "date": "2026-04-02T18:43:18",
    "name": "[nft,0/2] A bit of non-constant binop follow-up",
    "submitter": {
        "id": 4285,
        "url": "http://patchwork.ozlabs.org/api/people/4285/?format=api",
        "name": "Phil Sutter",
        "email": "phil@nwl.cc"
    },
    "mbox": "http://patchwork.ozlabs.org/project/netfilter-devel/cover/20260402184320.14862-1-phil@nwl.cc/mbox/",
    "series": [
        {
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            "url": "http://patchwork.ozlabs.org/api/series/498540/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=498540",
            "date": "2026-04-02T18:43:20",
            "name": "A bit of non-constant binop follow-up",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/498540/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/covers/2219290/comments/",
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        "From": "Phil Sutter <phil@nwl.cc>",
        "To": "Pablo Neira Ayuso <pablo@netfilter.org>",
        "Cc": "netfilter-devel@vger.kernel.org,\n\tDion Bosschieter <dionbosschieter@gmail.com>",
        "Subject": "[nft PATCH 0/2] A bit of non-constant binop follow-up",
        "Date": "Thu,  2 Apr 2026 20:43:18 +0200",
        "Message-ID": "<20260402184320.14862-1-phil@nwl.cc>",
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        "X-Mailing-List": "netfilter-devel@vger.kernel.org",
        "List-Id": "<netfilter-devel.vger.kernel.org>",
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        "MIME-Version": "1.0",
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    },
    "content": "When asked about how to translate ebtables' --arp-gratuitous match, I\nnoticed that basically everything is there already but the parser\nrejects it.\n\nWhile we can't do a simple 'arp saddr ip == arp daddr ip' because cmp\nexpression requires for one side of the equation to be constant, using\nXOR on LHS we can work around this limitation:\n\narp saddr ip ^ arp daddr ip == 0.0.0.0\n\nThanks to Jeremy's work on bitwise expression (which one might want to\nrepeat for cmp), the above is possible in VM code:\n\n[ payload load 4b @ network header + 14 => reg 1 ]\n[ payload load 4b @ network header + 24 => reg 2 ]\n[ bitwise reg 1 = ( reg 1 ^ reg 2 ) ]\n[ cmp eq reg 1 0x00000000 ]\n\nPatch 2 of this series relaxes the parser so it accepts the input.\nBasically it undoes an old workaround needed before we introduced start\nconditions.\n\nPatch 1 removes a similar restriction in JSON parser. It is needed at\nleast to accept the JSON equivalent of above match (conversion to JSON\non output was already correct).\n\nPhil Sutter (2):\n  parser_json: Accept non-RHS expressions in binop RHS\n  parser_bison: Accept non-constant binop on LHS of relationals\n\n doc/payload-expression.txt        |  6 ++++\n src/parser_bison.y                | 16 +++++-----\n src/parser_json.c                 |  2 +-\n src/scanner.l                     |  2 +-\n tests/py/arp/arp.t                |  4 +++\n tests/py/arp/arp.t.json           | 51 +++++++++++++++++++++++++++++++\n tests/py/arp/arp.t.payload        | 14 +++++++++\n tests/py/arp/arp.t.payload.netdev | 18 +++++++++++\n 8 files changed, 104 insertions(+), 9 deletions(-)"
}