sd-network: Rectify Advertise Message Processing by a Client

sd-network: Rectify Advertise Message Processing by a Client

We need to fix RCC 2215 behaviour with rfc7550 errata
and https://tools.ietf.org/html/rfc8415.

[RFC3315] specifies that a client must ignore an Advertise message if
   a server will not assign any addresses to a client, and [RFC3633]
   specifies that a client must ignore an Advertise message if a server
   returns the NoPrefixAvail status to a requesting router.  Thus, a
   client requesting both IA_NA and IA_PD, with a server that only
   offers either addresses or delegated prefixes, is not supported by
   the current protocol specifications.

   Solution: a client SHOULD accept Advertise messages, even when not
   all IA option types are being offered.  And, in this case, the client
   SHOULD include the not offered IA option types in its Request.  A
   client SHOULD only ignore an Advertise message when none of the
   requested IA options include offered addresses or delegated prefixes.
   Note that ignored messages MUST still be processed for SOL_MAX_RT and
   INF_MAX_RT options as specified in [RFC7083].

   Replace Section 17.1.3 of RFC 3315: (existing errata)

     The client MUST ignore any Advertise message that includes a Status
     Code option containing the value NoAddrsAvail, with the exception
     that the client MAY display the associated status message(s) to the
     user.

   With the following text (which addresses the existing erratum
   [Err2471] and includes the changes made by [RFC7083]):

     The client MUST ignore any Advertise message that contains no
     addresses (IAADDR options encapsulated in IA_NA or IA_TA options)
     and no delegated prefixes (IAPREFIX options encapsulated in IA_PD
     options; see RFC 3633) with the exception that the client:

       - MUST process an included SOL_MAX_RT option (RFC 7083) and
       - MUST process an included INF_MAX_RT option (RFC 7083).

     A client can display any associated status message(s) to the user
     or activity log.

     The client ignoring this Advertise message MUST NOT restart the
     Solicit retransmission timer.