Apparent dnsbl bug in Sendmail or m4

[John Nielsen]

It was pointed out to me that the example in freebsd.mc has been double-quoted for some time. That's what I get for carrying old config files around for too long I suppose. Sorry for the noise and thanks again all for the prompt replies.

On Aug 22, 2010, at 3:48 PM, John Nielsen <lists at jnielsen.net> wrote:

> On Aug 22, 2010, at 6:40 AM, Stefan Bethke wrote:
> 
>> Am 22.08.2010 um 10:00 schrieb Stefan Bethke:
>> 
>>> FEATURE(`dnsbl', `bl.spamcop.net', `"550 " $&{client_addr} "foo" $&{client_addr} ""')dnl
>> 
>> The real culprit is the comma.  I believe the problem stems from unquoted use of the arguments in some of the ifelses, where the comma turns the single argument into two.
> 
> That makes a lot of sense, especially when combined with the off-list suggestions I got to double-quote the error message.
> 
>> Tracing the ifelses with -d aceq I see this for the last ifelse in cf/feature/dnsbl.m4:
>> 
>> m4trace: -1- ifelse(`X"550 Mail from " $&{client_addr} " rejected', `see http://spamcop.net/bl.shtml?" $&{client_addr}', `Xquarantine', `R<?>$+         $#error $@ quarantine $: _DNSBL_SRV_', `X"550 Mail from " $&{client_addr} " rejected', `
>> see http://spamcop.net/bl.shtml?" $&{client_addr}', `Xdiscard', `R<?>$+         
>> $#discard $: _DNSBL_SRV_', `R<?>$+              $#error $@ 5.7.1 $: _DNSBL_MSG_'
>> ) -> ???
>> m4trace: -1- ifelse(...) -> `'
>> m4trace: -1- ifelse ...
>> 
>> 
>> I've never managed to really wrap my head around m4 quoting, but the easy fix is to use some other character that has no meaning to m4.
> 
> The fact that you knew how to do a trace shows that you're way ahead of me in grokking m4. :) I can confirm that replacing the comma with a colon makes the problem go away.
> 
> Does someone with some m4-fu want to take a stab at producing a fix? The problem appears in the 7-arg "ifelse" in the last few lines of /usr/share/sendmail/cf/feature/dnsbl.m4, though the source could of course be missing quotes earlier in the file.
> 
> I'd be happy to test any proposed patches and submit a bug report to Sendmail if appropriate. At the very least perhaps the example in the comment of /etc/mail/freebsd.mc should be modified to not use a comma.
> 
> Thanks!
> 
> JN
>