<html>
    <head>
      <base href="https://bugzilla.netfilter.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - nft -o optimizer fails to optimize birmasks"
   href="https://bugzilla.netfilter.org/show_bug.cgi?id=1784">1784</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>nft -o optimizer fails to optimize birmasks
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>nftables
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>1.0.x
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P5
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>nft
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>pablo@netfilter.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>neandris@gmail.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Lets feed following table (borrowed from tcp conntrack valid flags)

table inet t {
 chain c {
  tcp flags syn / fin,syn,rst,ack,urg
  tcp flags syn,urg / fin,syn,rst,ack,urg
  tcp flags syn,ack / fin,syn,rst,ack,urg
  tcp flags rst / fin,syn,rst,ack,urg
  tcp flags rst,ack / fin,syn,rst,ack,urg
  tcp flags fin,ack / fin,syn,rst,ack,urg
  tcp flags fin,ack,urg / fin,syn,rst,ack,urg
  tcp flags ack / fin,syn,rst,ack,urg
  tcp flags ack,urg / fin,syn,rst,ack,urg
 }
}

Outcome

Merging:
/dev/stdin:3:3-37:   tcp flags syn / fin,syn,rst,ack,urg
/dev/stdin:4:3-41:   tcp flags syn,urg / fin,syn,rst,ack,urg
/dev/stdin:5:3-41:   tcp flags syn,ack / fin,syn,rst,ack,urg
/dev/stdin:6:3-37:   tcp flags rst / fin,syn,rst,ack,urg
/dev/stdin:7:3-41:   tcp flags rst,ack / fin,syn,rst,ack,urg
/dev/stdin:8:3-41:   tcp flags fin,ack / fin,syn,rst,ack,urg
/dev/stdin:9:3-45:   tcp flags fin,ack,urg / fin,syn,rst,ack,urg
/dev/stdin:10:3-37:   tcp flags ack / fin,syn,rst,ack,urg
/dev/stdin:11:3-41:   tcp flags ack,urg / fin,syn,rst,ack,urg
into:
        tcp flags syn / { fin,syn,rst,ack,urg, fin,syn,rst,ack,urg,
fin,syn,rst,ack,urg, fin,syn,rst,ack,urg, fin,syn,rst,ack,urg,
fin,syn,rst,ack,urg, fin,syn,rst,ack,urg, fin,syn,rst,ack,urg,
fin,syn,rst,ack,urg }
/dev/stdin:3:3-11: Error: Binary operation (&) is undefined for set expressions
  tcp flags syn / fin,syn,rst,ack,urg
  ^^^^^^^^^~~~~~~~~~~~~~~~~~~~~~~~~~~

Expected - futile optimisation is not attempted. or skipped with warning
keeping original ruleset, or some syntax enhancement to make a set of comma
separated value groups (neither hex values work here) separated by commas /
mask.</pre>
        </div>
      </p>


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