[dnssd] SRP: Name Conflicts Handling

[Kangping Dong <[e-mail]>]

Hi DNSSD enthusiasts,

For Service Registration Protocol (SRP), when a SRP server receives a
registration with names
that have already been taken by another client, it responds with a YXDOMAIN
error code to indicate
name conflicts. When the client receives such a response, it typically will
re-generate a new host or
service instance name and re-register with the new name.

The problem is that a typical SRP update will include one Host Description
Instruction and one (or more)
Service Description Instructions (zero Service Description Instruction is
allowed but it is more common
that the client registers the host with some service instances). Name
conflicts can happen on both Host
Description instruction and Service Description Instruction, but there is
no description of how to tell the
client which instruction includes the conflict (or both include conflicts).
Currently, the client needs to re-new
both host name and service instance name or re-new a single name and starts
a trial-and-error process
until it finally succeeds.

One solution is, the server/registry responds with the *Instruction(s)* which
has name conflicts. For the
client, it should check the RRs in the response to get the conflicting name
if a YXDOMAIN response
code is received. To Reduce data transported between the server & client,
the server may just include
one RR, but not the entire *Instruction*, that contains the conflicting
name.

Thoughts?


BRs,
Kangping