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Ralsina.Me — Roberto Alsina's website

This can't be good

Work­ing on my SPF li­brary, I ran in­to a prob­lem. I need­ed to val­i­date a spe­cif­ic el­e­men­t, and the python code is a lit­tle hairy (it splits based on a large reg­ex­p, and it's tricky to con­vert to C).

So, I asked, and was told, maybe you should start from the RFC's gram­mar.

Ok. I am not much in­to gram­mars and parser­s, but what the heck. So I check it. It's a AB­NF gram­mar.

So, I look for the ob­vi­ous thing: a AB­NF pars­er gen­er­a­tor.

There are very few of those, and none of them seems very solid, which is scary, be­cause al­most all the RFC's de­fine ev­ery­thing in terms of AB­NF (ex­cept for some that do worse, and de­fine in pros­e. Did you know there is no for­mal, ver­i­fi­able def­i­ni­tion of what an Ipv6 ad­dress looks like?).

So, af­ter hours of googling...

Any­one knows a good AB­NF pars­er gen­er­a­tor? I am try­ing with ab­n­f2c but it's not strict enough (I am get­ting a pars­er that does­n't work).

Any­one knows why those very im­por­tant doc­u­ments that rule how most of us make a liv­ing/­work/have fun are so ... hazy?

SPF test suite on RASPF

Here are the re­sults as of right now:

  • Give the ex­pec­t­ed re­­sult­s: 82 tests

  • Give the wrong re­­sult: 48 tests

  • Give a cor­rect but not pre­­ferred re­­sult (most­­ly be­­cause of SPF records and IPv6): 6 tests

  • Fail (crash): 9 tests

So, de­pend­ing on how you look at it, RASPF pass­es be­tween 61% and 56% of the test­s.

Not bad so far :-)

Up­date: As of 20:52 ART, it's 105/0/35/5 and 72-76%. The bad news is that that was all the low hang­ing fruit, and now it gets much hard­er.

My SPF library kinda works

RaSPF, my at­tempt­ed port of PySPF to C is now at a very spe­cial point in its life:

The pro­vid­ed CLI ap­pli­ca­tion can check SPF records and tell you what you should do with them!

Here's an ex­am­ple:

[ralsina@monty build]$ ./raspfquery --ip=192.0.2.1 --sender=03.spf1-test.mailzone.com --helo=03.spf1-test.mailzone.com
Checking SPF with:

sender: 03.spf1-test.mailzone.com
helo:   03.spf1-test.mailzone.com
ip:     192.0.2.1


response:       softfail
code:           250
explanation:    domain owner discourages use of this host

Is that cor­rec­t? Ap­par­ent­ly yes!

[ralsina@monty pyspf-2.0.2]$ python spf.py 192.0.2.1 03.spf1-test.mailzone.com 03.spf1-test.mailzone.com
('softfail', 250, 'domain owner discourages use of this host')

Is it use­ful? Sure­ly you jest!

There are still the fol­low­ing prob­lem­s:

  • The mem­o­ry man­age­­ment is un­ex­is­­tant

  • I need to hack a way to run the of­­fi­­cial SPF test suite so I can see how well it works and that it works ex­ac­t­­ly as PySPF

  • It prob­a­bly will seg­­fault on many places

  • I am chang­ing the er­ror han­dling to be ex­­cep­­tion-based, thanks to EX­CC

  • The IPv6 sup­­port is be­tween iffy and not there

  • There is no sup­­port for SPF (type 99) DNS record­s, on­­ly TXT records (need to hack the udns li­brary)

But re­al­ly, this should be about 60% of the work, and it does work for some cas­es, which is more than I re­al­ly ex­pect­ed at the be­gin­ning.

Here's the whole source code of the sam­ple ap­pli­ca­tion (ex­cept for CLI op­tion pro­cess­ing):

spf_init();
spf_response r=spf_check(ip,sender,helo,0,0);
printf ("\nresponse:\t%s\ncode:\t\t%d\nexplanation:\t\t%s\n",
        r.response,r.code,r.explanation);

Some kind of landmark

As of right now, my cus­tomers owe me more than I billed in the sec­ond half of last year, and more comes due each month.

I sup­pose that's bad be­cause I am suck­ing at col­lect­ing. On the oth­er hand, it al­so means I am not suck­ing at billing. Or maybe yes, but much less than last year.

New look for this blog.

Af­ter many years, this is the first rad­i­cal change of look.

It's not very nice, be­cause my HTML skil­lz sux0rz, but hey, it's dark­er!

There are many lit­tle things wrong (like the col­or of vis­it­ed links) but I like it.

It's al­so a bit sim­pler, and I did the ban­ner us­ing inkscape (I had it done much nicer us­ing Kar­bon, but then I could­n't fig­ure out how to do the gra­di­en­t. Oh, well).

Up­date1: It looks in­cred­i­bly aw­ful on IE6, from the un­trans­par­ente PNG to the un­sup­port­ed over­flow:au­to I think I caught ev­ery damn thing that does­n't work :-)

Update2: Both IE and Konqueror will not use overflow: auto if the object is inside a table. In a blog that posts code and logs, and so on, that's a big problem.

So, to make this kin­da work, I had to get rid of (al­most) all ta­bles.

It looks ok now, ex­cept on IE the side­bar is at the bot­tom right, which is prob­a­bly be­cause it cal­cu­lates el­e­ment widths dif­fer­ent­ly.


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