Just point to the big "kludge" comment in gen_vlan().

The existing comment was one that was a copy of that comment, partially
but not completely changed to speak of PPPoE rather than VLAN
encapsulation.

[skip ci]

diff --git a/gencode.c b/gencode.c
index b4f2cc389279784b7023bbef3dab4198ff7cdaaa..7cb211c6dd0154a99b76142a388e93bcc6fcf82f 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -9127,29 +9127,8 @@ gen_pppoes(compiler_state_t *cstate, bpf_u_int32 sess_num, int has_sess_num)
         * the PPP packet, and note that this is PPPoE rather than
         * raw PPP.
         *
-        * XXX - this is a bit of a kludge.  If we were to split the
-        * compiler into a parser that parses an expression and
-        * generates an expression tree, and a code generator that
-        * takes an expression tree (which could come from our
-        * parser or from some other parser) and generates BPF code,
-        * we could perhaps make the offsets parameters of routines
-        * and, in the handler for an "AND" node, pass to subnodes
-        * other than the PPPoE node the adjusted offsets.
-        *
-        * This would mean that "pppoes" would, instead of changing the
-        * behavior of *all* tests after it, change only the behavior
-        * of tests ANDed with it.  That would change the documented
-        * semantics of "pppoes", which might break some expressions.
-        * However, it would mean that "(pppoes and ip) or ip" would check
-        * both for VLAN-encapsulated IP and IP-over-Ethernet, rather than
-        * checking only for VLAN-encapsulated IP, so that could still
-        * be considered worth doing; it wouldn't break expressions
-        * that are of the form "pppoes and ..." which I suspect are the
-        * most common expressions involving "pppoes".  "pppoes or ..."
-        * doesn't necessarily do what the user would really want, now,
-        * as all the "or ..." tests would be done assuming PPPoE, even
-        * though the "or" could be viewed as meaning "or, if this isn't
-        * a PPPoE packet...".
+        * XXX - this is a bit of a kludge.  See the comments in
+        * gen_vlan().
         *
         * The "network-layer" protocol is PPPoE, which has a 6-byte
         * PPPoE header, followed by a PPP packet.