On Thu, Nov 11, 2004 at 03:27:38PM -0800, william(at)elan.net wrote:
There's one piece of structure we may want to consider: The version.
domain.tld 86400 IN SPF 1 mx -all
domain.tld 86400 IN SPF pra ?all
Remember that version would need to be binary and not alphanumeric (it may
still be alphanumeric when record is entered if bind understands and knows
scopes) with its own IANA registry.
Sure, we need to really think about this. Separating the version could,
for instance, result in being able to query for a record that checks
RFC821 addresses, RFC822 addresses, or both.
As an example to start discussing: The two low bits (------10) could signal:
00: actively not participating in email (alias for "-all" ?)
01: check rfc821 headers only
10: check rfc822 headers only
11: check either or both
Querying for version 0x03 returns 0x01, 0x02 or 0x03 records.
Querying for version 0x01 returns 0x01 or 0x03 records but not 0x02.
0x00 will always be returned (if present) to any query. This could be
an implicit record (our much desired wildcard) if and when DNS servers
are configured to provide it.
Two more bits reserved (zero) for future use, i.e. new mail.
When using 16 bits, this leaves 12 bits for versioning. 12 bits should
provide enough room for future expansion, even if a couple of bits are
used for minor version numbers. I really can't see spf hit version 32
let alone version 128...
cheers,
Alex
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