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<p>Hi Stefan,</p>
<p>On Wed, Apr 08, 2026 at 08:54:52AM +0000, Stefan Pisjak wrote:</p>
<blockquote>
<p>I’ve searched through the documentation/this mailing list, but I
haven’t found anyone trying to build a similar filter so far.</p>
<p>I’m trying to build a filter to only allow BGP routes if the “host
part” of <code>ip from</code> matches the route that is being announced,
e.g.:</p>
<p>10.0.1.2 is allowed to announce 10.100.1.2/32 10.0.1.3 is allowed to
announce 10.100.1.3/32 […] 10.0.X.Y is allowed to announce
10.100.X.Y/32</p>
</blockquote>
<p>The easiest way would probably be to extend the
<code>FI_BITAND</code> and <code>FI_BITOR</code> operators for not only
<code>T_INT</code> but also <code>T_IP</code>. Relevant code is in
<code>filter/f-inst.c</code>, test file is
<code>filter/test.conf</code>, feel free to send a patch.</p>
<p>These two operators are currently in BIRD 3 only because the weren’t
needed in BIRD 2; feel free to backport them if needed.</p>
<blockquote>
<p>But as far as I can tell, it’s not possible to somehow convert the
type ip to type quad or something like that. Is there a better way to
build this filter, or can you somehow create a new variable of the type
ip and modify it or convert the ip to a quad and then do the
manipulations?</p>
</blockquote>
<p>Explicit type conversion of this kind is something much harder to
implement in a maintainable way.</p>
<p>Happy routing!<br />
Maria</p>
<p>–<br />
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.</p>
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