Mailing List Archive: What to do if is empty string

Grammar in "draft-mengwong-spf-01.txt" define <domain-spec> so that it
can be an empty string. We can also get an empty string after macro
expansion.

For example, following SPF record is grammatically valid:
v=spf1 +mx:/24 +a:/16 +ptr: +include: +exists: redirect= exp=

In case of a, mx, ptr mechanisms we can use <current-domain>. But what
about others?

There are two questions:
1. How to interpret empty <domain-spec> in context of various
mechanisms and modifiers?
2. What to do if we get empty string after macro expansion of
<domain-spec> in context of various mechanisms and modifiers?

- Igor

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Igor wrote:

> 1. How to interpret empty <domain-spec> in context of various
> mechanisms and modifiers?

My SPF implementation does it as follows:

a: use current-domain
mx: use current-domain
ptr: use current-domain
include: syntax error --> 'unknown'
exists: syntax error --> 'unknown'
exp= explanation reset to none
redir= redirection reset to none

> 2. What to do if we get empty string after macro expansion of
> <domain-spec> in context of various mechanisms and modifiers?

An empty string after macro expansion is not possible except if there is an
invalid macro character. That would be a syntax error and you should return
'unknown'.

Roger

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