[babel] Packet trailer

[Juliusz Chroboczek <[e-mail]>]

In RFC6126bis Section 4.2, I say:

   The packet body and trailer are both sequences of TLVs.  The packet
   body is the normal place to store TLVs; the packet trailer only
   contains specialised TLVs that do not need to be protected by
   cryptographic security mechanisms.  When parsing the trailer, the
   receiver MUST ignore any TLV unless its definition explicitly states
   that it is allowed to appear there.  Among the TLVs defined in this
   document, only Pad1 and PadN are allowed in the trailer; since these
   TLVs are ignored in any case, an implementation MAY silently ignore
   the packet trailer without even parsing it, unless it implements at
   least one extension that defines TLVs that are allowed to appear in
   the trailer.

In Appendix C, I say:

   The packet trailer is intended to carry cryptographic signatures that
   only cover the packet body; storing the cryptographic signatures in
   the packet trailer avoids clearing the signature before computing a
   hash of the packet body, and makes it possible to check a
   cryptographic signature before running the full, stateful TLV parser.
   Hence, only TLVs that don't need to be protected by cryptographic
   security protocols should be allowed to appear in the packet trailer.
   Any such TLVs should be easy to parse, and in particular should not
   require stateful parsing.

Speak now, or forever hold your peace.

-- Juliusz