Mailing List Archive: Macro expansion

Macro expansion

Jun 8, 2004, 2:10 AM

Post #1 of 3 (1308 views)

Testing my SPF implementation against Wayne's test suite from
http://www.midwestcs.com/spf/tests/tests_v2.1/test.txt, I came across the SPF policy record in

99.spf1-test.mailzone.com

which is

v=spf1 -all exp=99txt.spf1-test.mailzone.com moo

The explanation TXT expands to

"u=%{u} s=%{s} d=%{d} t=%{t} h=%{h} i=%{i} %% U=%{U} S=%{S} D=%{D} T=%{T} H=%{H} I=%{I} %% moo"

The latest draft specification doesn't document the "u" macro, nor does it indicate what to do when
faced with a macro that is not documented - do you report (unknown) error for the policy (seems a little
harsh), do you ignore the macro completely, or should it be replaced with some simple string, e.g.
"(unknown)"?

Any help appreciated,
Thanks,
Gary Levell

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Re: Macro expansion [ In reply to ]

mengwong at dumbo

Jun 8, 2004, 11:31 AM

Post #2 of 3 (1296 views)

Permalink

On Tue, Jun 08, 2004 at 10:10:45AM +0100, Gary Levell wrote:
| Testing my SPF implementation against Wayne's test suite from
| http://www.midwestcs.com/spf/tests/tests_v2.1/test.txt, I came across the SPF policy record in
|
| 99.spf1-test.mailzone.com
|
| which is
|
| v=spf1 -all exp=99txt.spf1-test.mailzone.com moo
|
| The explanation TXT expands to
|
| "u=%{u} s=%{s} d=%{d} t=%{t} h=%{h} i=%{i} %% U=%{U} S=%{S} D=%{D} T=%{T} H=%{H} I=%{I} %% moo"
|
| The latest draft specification doesn't document the "u" macro, nor does it indicate what to do when
| faced with a macro that is not documented - do you report (unknown) error for the policy (seems a little
| harsh), do you ignore the macro completely, or should it be replaced with some simple string, e.g.
| "(unknown)"?
|

hm. u and l were supposed to be synonymous --- just as some
people think of "username" and "localpart" as synonymous.

when faced with an undocumented macro, you, uh, replace it
with a zero-length string.

so "%{?}" becomes ""

when undocumented macros are used to construct a
domain-spec, consecutive dots are compressed.

so "foo.%{?}.bar" becomes "foo.bar" because the ".."
collapses to ".".

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Re: Macro expansion [ In reply to ]

wayne at midwestcs

Jun 8, 2004, 12:30 PM

Post #3 of 3 (1296 views)

Permalink

In <20040608183153.GK2112@dumbo.pobox.com> Meng Weng Wong <mengwong@dumbo.pobox.com> writes:

> | The explanation TXT expands to
> |
> | "u=%{u} s=%{s} d=%{d} t=%{t} h=%{h} i=%{i} %% U=%{U} S=%{S} D=%{D} T=%{T} H=%{H} I=%{I} %% moo"
> |
> | The latest draft specification doesn't document the "u" macro, nor does it indicate what to do when
> | faced with a macro that is not documented - do you report (unknown) error for the policy (seems a little
> | harsh), do you ignore the macro completely, or should it be replaced with some simple string, e.g.
>
> hm. u and l were supposed to be synonymous --- just as some
> people think of "username" and "localpart" as synonymous.

The only place that I have ever seen the 'u' macro used is in this
test case. I believe it was documented in an earlier draft.

> when faced with an undocumented macro, you, uh, replace it
> with a zero-length string.

to the best of my knowledge, this is not in the spec. libspf-alt
considers it a syntax error and response accordingly. The same goes
for things like unterminated macro variables (e.g. "%{l.foo.bar"),
invalid separater characters (e.g. "%{l{}.foo.bar"), etc.

> when undocumented macros are used to construct a
> domain-spec, consecutive dots are compressed.

compressing consecutive dots is not documented in the SPF spec. If
someone creates an invalid domain name for some reason, it is a bad
idea to try and guess what the "correct" name should be.

All of the quirks in the the perl implementation should *not* be the
final word on what SPF is.

-wayne

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